Tuesday, January 25, 2011

Speedster Redux and the Zeva2 Fuel Gage

This week we go a little bit more in-depth with Ian Hooper's Zeva2 fuel gage driver.  I'm quite enamored of this little device which he apparently is still building by hand.  And improving.

In the latest incarnation, he's solved the fuel gage direction problem by using a 20 turn potentiometer.  The direction is indicated by which side of pot center you are on and the discharge rate, or really capacity of the cell, is indicated by how far from center you adjust it.

There are two other features I'm particularly excited about. First, it provides an instantaneous current indication as a series of pulses designed for a tachometer. A pair of little microswitches allows you to set your pulse count as in four cylinder, six cylinder, eight cylinder, etc. And the device automagically and with NO calibration puts out pulses to correlate 100 amps with 1000 rpm.

We set this up with a switch on the dash to switch either our normal RPM from the RECHARGECAR magnetic pickup on our motor, or this Zeva2 current output. I can switch between them at the press of a button.

I cannot express how much of a difference this makes.  Digital displays of rapidly changing current loads are just not very useful.  They update at the update rate of the display, and the result is just a dancing number, meaningless and without form.  When you put this on a BIG needle on a BIG gage, suddenly, it has all the missing rate and direction information - trend if you will.  We may only hit 1000 amps briefly.  But we'll get to see it.

Actually, as it stands, we won't.  We have a 6000 rpm tachometer and so our max display would be 600 amps.  I have a 10,000 rpm tach on order with Speedhut.

The fuel gage output is a rough AH count.   It uses a hall effect current device to measure current and integrates by summing instantaneous current outputs over time.  I've read endlessly how inaccurate and "drifty" this is.  Methinks they are letting the perfect delay and obscure the good.   Comparing hall effect output at different temperatures to the more conventional current shunt meters such as the TBS ExpertPro, I've found them within fractions of an AH after 100 amphours in and out.  Yes, it differs.  Yes, they drift.    But we're not building a piano here.  PLus and minus an amp hour would be plenty.

But charge and recharge errors can be cummulative over time.  We don't want to "get lost" on our pack SOC.  The answer is of course to reset the counter at the end of a charge cycle.  It would be nice if this were done automatically, but it is easy enough to do.

Unfortunately, the Zeva2 is a little crude in this respect.  You simply remove 12v power from the device and it resets. Also unfortunate, if you hit your maintenance switch to do some maintenannce, it also resets the device and you lose your AH count.

The solution was the addition of three components:  A LiPo battery backup, a diode, and a switch.  The LiPo powers the box when it loses system 12v.  The diode keeps the little LiPo battery from trying to power the car in this event.  And the switch lets us reset the device when we want to.

The Zeva2 is also a bare PCB with the hall effect mounted directly on it.  So we need to get it out of the weather.  That requires a plastic enclosure.  Since the conductor has to pass THROUGH the hall effect device, it also requires a couple of LARGE gland nuts or nylon domed cord grips to pass the cable through the box.

Finally, the Zeva2 provides an adjustable LED warning light driver you can use to turn on an LED when SOC reaches an adjustable level.  This is a five volt pullup with a 1k resistor.  We'll have to use a MOSFET or Darlington or some sort of thing to convert that into a 12v switch to actually do something useful, like disable our controller or switch a resistor across our throttle output to put it in limp mode.

I would prefer the LED circuit to actually provide a 3A relay.  But it is what it is.  At $179, that's pretty good.

In this episode, we also show some progress on Speedster Redux.  Our belly pack worked out pretty well, we have it installed beneath the frame quite securely.  This aluminum structure only projects 1.75 inches down, still leaving us with 7.5 inches of clearance, and provides room for 11 cells.  That's a 36 volt pack at 180AH for 6480 wH or an additional 28 mile range, more or less.

Matt Hauber engineered a front battery box allowing us 18 cells vice the 16 we had at that location in Speedster Part Duh.  And he built two rear battery boxes featuring 11 cells each instead of the 10 cells in each box we had in Duh.

We moved the Soliton1 to an aluminum shelf mounted to the motor and adapter plate.  This shows off the Soliton1 look very nicely.  It also made room for six more cells up on the shelf with a terminal strip and easy access to the cells and connections.  

We're also using EVWorks braided cell straps, with our own M8 bolts and NordLock washers to strap up.  These are working out marvelously.  The straps make a very flat, very strong connection between cells and the Nord Locks have just been a find.  They really grip it - forming a very tight connection that does not seem to loosen at all over the brief period of time we have been using them.  Infinitely superior to the lockwashers we once used.

For 180AH CALB cells, the 80mm straps seem to be the most useful.  Occasionally a 70mm strap is necessary to keep from humping up.

For cabling, we're using some yellow 2/0 from Genuindealz that is really quite good.  It's tinned and intended for marine use.  This makes it just about all you can squeeze into a 2/0 lug, but if we DO do 1000 amps briefly, I want the metal to handle it under that insulation.  It certainly was a pleasure to deal with the 1AWG we used a lot of in the much higher voltage, much lower current Mini Cooper.  But Speedster Redux probably needs the larger, albeit stiffer cable.  It's too bad I can't get this tinned marine cable in the proper International Orange color.

In this week's show, we also show my somewhat crude mounting of a J1772 inlet in the Mini Cooper.  I've grown to like the solid feel of the J1772 Yazaki plug.  We have it on the Texaco Fire Chief Plasma Ball Charge station now.  And we've added an interesting voltage/current/power meter from http://www.lightobject.com to that charge station.

Jack Rickard


  1. Your experience with DHL had me laughing so hard I almost cried. I've had thier drivers actually lie about the status, saying they "attempted delivery", but in fact no vehicle ever showed up at our facility which is open 24x7. Just one of the perks of living in a rural area, I guess.

  2. Jack, the relay drive circuit for your Zeva2 AH meter looks a little off. For one, I believe you have the drain & source leads reversed on the FET. Second, there should be a back-biased diode across the coil of the relay to deal with the voltage spike when the magnetic field collapese. Third, why not just use the drive circuit you used here, replacing the transistor with a FET: http://2.bp.blogspot.com/_i_c2BM_uBw4/TTmR5kkwigI/AAAAAAAACEM/xTuo09FdVfc/s1600/J1772chargestationcircuit-1.jpg Also, if your "daughter circuit" shares the same ground as the Zeva and you are just shunting a resistor to ground, get rid of the relay and let the FET shunt the resistor to ground instead of the relay. -Klaus

  3. Jack, I just wanted some clarification about your comment on the Zeva unit when it resets. When power is removed you say it resets the device. I'm assuming that you only mean the once reset it assumes you have a full pack. Surely you don't mean that the pots need to be repositioned to set the pack size again. How often do you expect that you'll be using the maintenance switch and the pack wont immediately be recharged? It seems like a lot of work to do this when almost anytime I use the maintenance switch I'll be recharging as well so they will both be put back at the same time. It does seem like a simple fix for the designer to install a small battery or capacitor and a switch to do what you are doing all on the board itself. Perhaps Zeva3.


  4. Thats wonderful, if you like the functions
    of the Zeva!
    a few months ago, i programmed almost the
    same thing.... only a few parts
    around an Atmega48...
    For measuring i use a LEM-HASS200
    I added a LCD-display for monitoring and
    (Capacity can be entered
    and saved in a menue for example)
    I promise, i did not know the Zeva!
    There are things, the world simply needs!


  5. I love analog meters for things like this! Try peaking a circuit or a laser with an digital meter... Uhg!

    Jack, can you provide a link to the DC to DC converter source you mentioned?

  6. No. The pots don't need to be repositioned. It just resets the AH count.

    Yes, the relay circuit is a mess, a quick sketch. I often omit the diode and usually get away with it. The throttle has a separate 5v supply and return. I'm a little leery of mixing frame ground with the 5v signal return.


  7. The diode is not needed as long as the transistor is rated for the voltage spike produced by the relay coil.
    In fact I leave the diode out in case where I want a fast reacting disconnect of the relay. The diode will enable the current in the coil to circulate and thereby delaying the release of the relay contacts.


  8. Hey Jack,

    What do you think about triggering off the charger when a full charge completes reset the fuel gage?

    This way it stays more accurate with every full charge.

    Thanks, Jim

  9. Jim,

    The idea is ok, if you are certain that the charger shuts off because it has reached full charge and not just because somebody pulled the plug.


  10. I love this type of show! Getting down in the weeds with the Zeva or building battery boxes or running wires - that's what I want to see more of...I don't mind the yakking and wine discussion either. Keep it up Jack, love it!


  11. I like the idea of triggering off the charger. But it doesn't need all that. All you need is to trigger off a voltage - one that only occurs during a charge. I hate to say it, but it should be part of the Zeva and I'm loathe to try to cobble something together there.

    In this case, our nominal will be 191 volts, but we will charge to about 200. It would be simple for Ian to set it to reset when voltage > x, like 199. But then THAT would have to be adjustable as well. I hate to featuritus the guy, but that's really where it should be. You just have to pick a voltage that only occurs at max charge.

    Jack Rickard

  12. Martin:

    Actually there is a paper put out by Kilovac Tyvek on why NOT to use diodes with their contactors. And yes, you're correct they can cause problems even with small relays. As for simple circuits like this, I don't put a lot of time into the calculations - I usually just want something to swtich on or off. There are some oddities that arise with small coils, diodes and other semiconductors - ergo all the CAPS then and the next thing you have a bunch of components to do a very simple thing.

    I was kind of sketching out the logic of what needed to be done, and didn't mean to do component selection for it literally. But I guess in for a penny, in for a pound. I should have just worked it out in detail and put it up on the board.


  13. Jack - the Soliton1 can tell you - via it's programmable outputs - what the motor amps are on a plain old analog gauge (or a digital one with some RC filtering). Yes, I do need to describe these in much more detail - at the time of the last manual revision the programmable outputs were a relatively new addition.

    At any rate, the three programmable outputs were originally meant to drive low power relays and such but one of our first customers asked if they could be used to somehow show motor amps (among other things). Me and the programmer, Martin (aka Qer) gave it some thought and after a bit of tinkering and kludging found we could generate a 0-100% duty cycle signal on them at 60Hz. The outputs just switch the incoming 12VDC supply so this isn't terribly precise (though you can clip the signal with a resistor/zener to something more consistent) but it's not any less accurate than the typical analog gauge, which it can drive directly without any additional filtering (the mechanical gauge movement is an effective integrator).

    One popular use is to drive a 1000A gauge meant to work with a 50mV shunt directly from the Soliton1 - that is, without having to use the shunt. Just put a 100 ohm resistor in series with the programmable output and then a 0.47 ohm resistor across the gauge and the maximum output of ~12V * 100% duty will be divided down to ~50mV, which is exactly what the gauge expects at full scale. Set the relevant output to report "motor amps" in the web interface and you are done.

    Then use the tachometer you bought to report RPM as it was meant to do ;)

    BTW - feed the signal from the RechargeCar to the Soliton1 and then connect the tach to one of the programmable outputs. This lets the controller protect against motor overspeed (as well as idle the motor for running an A/C compressor, keeping an auto tranny pumped up, etc.) and the programmable output can send a signal to the tach with the same, or a different, number of pulses to match what the tach expects (e.g. - a 4 cyl. tach expects 2 pulse per turn; a 6 cyl. expects 3, etc.).

    All of the aftermarket tachs we've tested so far seem to accept the signal from the Soliton1's programmable output as valid as long as there is a load resistor from the output to ground. 1k seems to work but you can go as low as 33 ohms if you need to (try to use the highest value resistor that you can get away with though).

    If you need more specific help just ask. The Soliton1 has all sorts of cool functions thanks to our most excellent programmer that might eliminate the need for a lot of external kludges and doo-dads (or encourage their proliferation - depends on your personality).

  14. Martin is indeed a wizard. I'm a fan. I posted to another entry our experiences bringing this Soliton1 up. It is just very slick and very easy to get off the ground. The firmware update is the best I've ever dealt with.

    But yeah, you need some of that implementation info on the inputs and the outputs. Motor temp sw. Does this only work with the snap switch. Can I put a thermistor in for actual motor temp?

    We simply ran the rechargecar pickup to the Soliton1 and then ran from the same terminal to the tach. Both seemed to work and neither seemed to load the other. No resistors. Nada. In fact, we used the ground and 12v from the Soliton, and juat ran the signal line up to the tach.

    I don't really want another 1000A meter. I LIKE the big tach display of current from the Sheva and the ability to switch between them. We need instrumetation, but not like 30 dials across the dash after the fashion of the Linkvolt. We're trying to know more with less here.

    AH counting is a big deal here. My wish list would be for that to come from the Soliton. But there really isn't a good way I can see to get charger AH counted in as part of that. So there's little point in mentioning it.

    But yes a little diagram for the amp output in the book showing the 100 ohm and 0.47 ohm divider would be huge for pointing up typical uses for outputs and inputs.

    All in all, I was stunned with the software design. It matches the case. Just a thing of beauty and simplicity. The firmware update is just shockingly well done. Why everyone else struggles with this so is beyond me. Please convey my sincere admiration to Martin. What does "Qer" imply?

    In any event, we rolled last night. Some minor HID headlight problems. But the controller seems smooth and slick. Oily.

    When can we get you guys up to do a show?

    Jack Rickard

  15. "Martin is indeed a wizard. I'm a fan."

    Thank you. :)

    "Can I put a thermistor in for actual motor temp?"

    It's been considered, but the problem is that it would have to be a pre-mounted thermistor built into the motor to be useful plus that it'd be very complicated to have more than a very few selected ones to choose from.

    Kostov does have such a thing in their motors so it'd make sense to support their thermistors. I've been considering that for a while (something like at least a year) but then there's that issue with time. It will probably happen eventually though...

    "AH counting is a big deal here. My wish list would be for that to come from the Soliton."

    Unfortunately that will never happen since the Soliton would lose count every time you power cycle it.

    "What does "Qer" imply?"

    Nothing. It's just random hammering on the keyboard when I had to come up with a nick in the online game Guild Wars. I've stopped playing GW but the nick kinda got stuck and is used in various online forums and games.

    "When can we get you guys up to do a show?"

    Very hard to tell since I live on a different continent.

  16. You've been in the garrett programming to long then. In the interim while you were otherwise occupied with Guild Wars, we've developed the square rigger with rudder and other ship developments that have pretty much conquered the Intercontinental travel thing.

    Don't get me started on airplanes....they came later of course.

    Jack Rickard

  17. If You dont like diodes at a relay coil,
    (timing-reasons etc...)
    you can also use a resistor to decrease
    the voltage-spike just a little bit
    and not completely, for protection of the
    when switching off the coil.


  18. Hi Jack & Brian, thanks for another great show. I bought orange shrink tube from BuyHeatShrink.com and slipped it over my existing cables because I didn't want to redo my cables. Fast and easy and looks good too.

    Mark Urban

  19. Hi Jack,

    Men, you have such a spirited response in the Thundersky Yahoogroup. I can almost imagine a western style gun duel, mano-a-mano fight against the BMS guy....


  20. At high noon. Be in the street, if you dare...

    Yeah, I'm getting a thing on for these BMS charlatans. Their greed over truly chump change, none of them really makes any money, is threatening the rest of us with regulation if the fires continue. I used to view it as innocently inept amateur engineer wannabes. But after the first dozen cars burned to the ground, I began to see what a disservice they do to all the new people coming into the field and how this warps the public perception of electric car safety. And they can be quite vociferous in THEIR views online. They are accustomed to haunting every known forum, trying to find a market for their stuff at no advertising cost, and so they can afford much more time to it than I can. If you'll ook back through the messages, you'll find that I was providing very low key information, and "I" was the one attacked. Both of these gentlemen, Mark and Mikeepeep, are wannage BMS entrepreneurs. So it is all a bit for show. They hope to raise a rabble and the concept is for me to cower and slink away. As you can see, not my style.

    Fortunately, my introduction to online forums and mailing lists was in the 1980's with some truly not nice people. So I'm accustomed to the heat and don't mind it at all. The irony is, that they just go from forum to forum, I've heard from Mikepeep plenty. But the Thundersky is fairly low key and I've been in it for a number of years. These newbies just don't know any of the history. A guy named Jan and I used to constantly theorize about how to build a better shunt BMS in those days. We both found out the same thing on two entirely different workbenches separated by 400 or 500 miles. The components in the BMS are less reliable than the batteries. So it's kind of a fool's errand.

    So it's really kind of funny, however dire it may sound;

    Warmest Regards;

    Jack Rickard

  21. Regarding orange cabling, I found some orange plastic wire loom on ebay that I slid over my black battery cables. That provides the proper color and an extra level of chafe protection, and since it's split can be slid over cables that are already in place without removing them.


  22. Chaff protection? one can buy, (amongst other names), "spir wrap". Comes in many colours and diameters. Stopped chaffing wiring looms on a few motorbikes in my time.

    Beware the price! Sometimes its very expensive. I was lucky with my job.

  23. Jack, I asked it once bevor, but it seems that I missed the answer.
    Why do you not get the Zivan chargers in your reports?
    Is there a reason why you don't use them?

  24. THere is. I don't like them. And if we devoted space and air time to all the things that DON'T work, we'd have no time or space for those that do. What to leave out. What to leave in. Me and Janey and the radio down low....

    ....Bob Seeger....

    Jack Rickard

  25. http://www.merriam-webster.com/dictionary/chaff


  26. Hey Jack!

    Great Shows.

    How about dropping a $50 12-volt motorcycle battery into Speedster Redux, temporarily, to get her out on the road? You're killing me with "waiting for perfect", getting in the way of "demonstrating greatness".


  27. Hello Jack,
    Great series of programmes, I don't know whether you have mentioned this company before www.byd.com/ but their E6 is a newly completed vehicle on sale now in China. They have a large quantity in use as cabs in Shetzen. Apparently Warren Buffet has invested $200 million in them. They started by manufacturing mobile phone batteries and saw the future in electric cars and built a car plant some 1.5 miles long to produce the cars.
    Not as fancy as the Tesla though, but they say the E6 has been designed ground up to be a battery powered vehicle.

  28. We've mentioned it before and we are aware of it. The problem is they made some wild claims that they would have them available by the end of 2010 in the U.S. Didn't happen. Then thousands in China. Didn't happen.
    Then thousands of taxis. Actually about 50. Now they're coming at some point. Ok.

    I don't know what to make of it. I know this guy at the top of this company is a little fascinating. He goes around and hires the top grads in Engineering from ALL the Universities in China. Then he sends them to his own school for a year, and washes half of them out. THe survivors go into a huge campus of tens of thousands of these engineers. They get about $600 per month, but they also get all their medical, their housing, their utilities, and I think their food. They work 100 hours per week, just like the head of the company.

    As I read and learn more about this fascinating company, and I look around us here in the U.S., I confess some unease. And an odd compulsion to order a copy of Rosetta Stone, Mandarin version.

    Aside from the rather inevitable conflict between a linear growth curve in oil production and an exponential growth curve in both the number of fossil fuel powered vehicles and indeed our population itself, I have two fears.

    The first is that the Chinese will take over America we will all wind up working for the Chinese.

    The second is that after a careful examination, they won't want us and will take over and hire the Brazillians instead.

    Jack Rickard

  29. I can recommend the Pimsleur Mandarin courses!

  30. 100 hours a week? There's an awful lot of coffee in Brazil.
    I've added some water to the BMS fire now.... Joined the Yahoo Thundersky group!

    Well, I pee'd on somebodies opinion of "engineers".

    A fire needs three components to burn:

    Nobody in the real world designs a car with a gasoline fuel tank over the electrics and engine do they. So why insist on placing circuits directly over the batteries?

  31. Great show this week Jack.

    Hey, did anyone make it to the Saint Louis Auto show over the weekend? My son and I drove from Columbus, Ohio...Needless to say we were a little disappointed. All was not lost, it was a great day and we enjoyed taking pictures along the water front and touring the Arch Museum.

  32. JPR3
    What was I thinking. :)))
    Chafe not chaff.
    Chafing is good in some versions of English. In lieu of:

    Abrasion and work hardening of Jacks wires in his mini due to dangle.

  33. Good video on DC motors and PWM controllers.

    Some time ago I encountered an clever mechanical PWM controller. It had a 4 segment conductive cylinder spun by an electric motor at a constant RPM. The segments are only mechanically connected, not electrically. Two brushes sit side-by-side and are connected to be a switch to the main drive motor, not the little motor spinning the cylinder. One of the two brushes contacting the cylinder can rotate along surface of the cylinder relative to the other. With the brushes side-by-side and the cylinder spinning, the duty cycle to the drive motor is 100%. With the brushes at 95 degrees to one another, in the direction of the rotating cylinder, the duty cycle is 0%. I think they were used in trolleys back in the day but I can't find the link to the article. -Klaus

  34. Klaus.
    It might be the "MagneTek flux vector variable-speed drive"?
    I quote:
    The ability to provide 100% torque at 0 rpm, a full-torque, soft-starting capability;
    A stepless speed range of 1,000 to 1, an improvement over the previous four-step arrangement;
    Continuous speed regulation of 0.01%;
    Torque limiting to protect vintage tram machinery...

    If I remember correctly. It had a control lever that rotated a little over a quarter turn to include a slow reverse. This might be a variable advance and retard control. I love old solutions to problems but this one is no good for EV's. :))

    PWM circuits are fun. Me and a friend once tried microwave cloud bounce using PWM for the audio carrier.

  35. m1aws,

    No the MagneTek doesn't seem to be it. The MagneTek seems to be for AC drive system, not DC as was the unit I tried to describe. PWM circuits are fun. The real reason for PWMing LEDS is to maintain color temperature. Simply reducing the current dims them but also changes the color temperature slightly.

    I came across anther mechanical PWM unit that used a copper sign wave conductor wrapped around a spinning cylinder. Opposing brushes slid up and down opposing sides of the cylinder for PMM control. Electronic PWM is the way to go these days but I always find it interesting to find mechanical counterparts to electronic circuits. Cool on the microwave cloud-bounce. Were you successful? -Klaus

  36. UK Trams were DC.

    Cloud bounce,
    Sometimes successful - Skype on a bad day. It made a better UFO detector. The very low power allowed on that band and lack of handy dishes did not help in our cloudy England.

    I sent the 555 circuit to show the motor drive version for brave people. It can be used to make fixed voltages too.

  37. Hi Jack

    Why dont you explore that bms lvc function on the Soliton1 to se if you can hook the zeva2 that way. It all depends on what the controller does with the information, maybe you can set it to daugther mode if that input is triggered.


  38. Talking (again) about BMS. One pro BMS'er says he has blown a 200AH battery feeding it with 3.65V and under 200mAH with a lab power supply. He forgot about it through the weekend.

    Is this possible?

  39. What you state is simply not possible. What you mean to state might be. If you have a cell at 3.65v and add 200mAH, it will do nothing.

    If you had it at 200ma of current and were holding it at 3.65 volts over a weekend, I am not sure WHAT the reaction would be. I suppose you could overcharge the cell.

    The result and the question all go to the same gent - a pro BMSer. These guys simply REFUSE to understand, I know they CAN understand because we've explained it every way from sunday. The 3.65 is NOT a cell voltage. It's a reading while you are charging.

    The fully charged voltage of LiFePo4 cells is 3.4 volts. The 3.65 or 4.20 or 3.75 or 3.50 is a DESCRIPTION of a CHARGE CURVE you can perform AUTOMATICALLY or MANUALLY to reach a state of full charge. AFTER you have added that much energy, if you disconnect the charger and let the surface charge dissipate, the cell will soon come to it's true state of charge. You can measure this with a voltmeter. It will be somewhere below 3.4 volts.

    We UNDERCHARGE our cells slightly and on purpose. And we will typically see 3.33 to 3.35 volts per cell in a fully charged state.

    They get terribly confused that the cell should be at 3.65v. Trickling in 200 ma or other low levels of current simply flattens the charge curve but the objective NEVER WAS 3.65volts. It was 3.4 volts open circuit.

    IF you follow the manufacturers charge curve, you can get there. There is no 200 ma in that description.

    Cells in series have variations that preclude the lab charge curve. And so we offer a modified charge curve to a lesser voltage, but otherwise identical. This slightly undercharges the cell.

    Adding 200mAH of energy, that is .2AH won't do anything noticeable at all to a 200AH cell.

    Holding it at 3.65v, even at a very low level of 200ma, most probably would in some time frame and I don't know what that time frame might be.

    In any event, it's no indication he needs a BMS. He needs a basic understanding of cell charging.

    That said, I've myself left batteries on in the lab, and you've all seen the consequences.

    Proper charging is crucial to these cells. A BMS is not only not a solution, but seems to be a REGULAR schema to overcharge cells, and to burn shit to the ground.

    Get a good charger to begin with, and understand what it is supposed to do, then make CERTAIN that it is doing it, by verifying and repeating it a few times. Once it's doing it, most chargers will do it every time, unless YOU change something. In a system complicated by too much circuitry, you can occasionally trick it into failure.

    Jack Rickard

  40. Per. Not a bad idea in concept, in operation not so good.

    The Soliton1 is kind of stuck on the concept of 12v or gnd. And I'm sympathetic to that. Automotive environments are just not very good with TTL signals. The noise can wipe them out.

    The Zeva 2 puts out a 5v signal at a 5ma level. About enough to light a SMALL LED.

    What I've done is put an eggregiously overspec MOSFET IRFZ44 as I recall, with a 7.5 ohm gate resistor to ground. This switches 12v through the coil of a small relay. The relay applies a 3.3k resistor across two wires, which we could connect to the throttle for daughter mode.

    But I also use the relay to switch it's own 12v source out another pin. I was going to use this to light an LED, but one of the 12v LED lights that already have bidirectional and the correct limiting resistor internal.

    I COULD switch that 12v output to the Soliton1. I don't know if that would activate the BMS LVC circuit or not.

    But I'm tempted. I connected the 120C temperature snap switch from the Netgain motor to the MOTOR TEMP SW input of the Soliton intending for it to shut down in the event of a 120C event on the motor.

    It didn't work. In fact, just by selecting the MOTOR TEMP SW in the software, the system went into a permanent limp mode.

    The limp mode was actually pretty pleasant and pretty limp. I kind of liked it. It may be a more reliable way of accomplishing what we're after here.

    So we may explore this. I first have to understand why the thing goes into limp over the snap switch, even with the snap switch disconnected.

    The snap switch is simply a NO - open all the time. IF the motor sees 120C, it closes. We were going to apply 12v to it. But the systems went into limp mode without activation, and indeed we disconnected the temp switch from the SOliton1 and it STILL went into limp mode until I changed INPUT 1 to OFF.

    I asked Sebastien about this by e-mail but haven't been graced with a reply as yet.

    But yeah, it takes a bit of circuitry but we could use the Zeva2 output to trigger the Soliton1.

  41. In an ideal world, we're kind of chasing our tail here. The Soliton1 measures current. It could easily totalize it. It's a few lines of software to measure current and set a clock. The next time you "get around tuit" in the software, you check the clock for elapsed and multiply it by the current measurement, assuming it has been the same since the last check, yeah verily these many milliseconds ago and totalize it - resetting the ticker of course.

    Of course you do have to write this value to an EEPROM or something so it is retained after you park at the local dogfight/brewhaus. And so you hae to reload it on power up, which is one reason not to bother.

    If they DID bother, it kind of obviates the need for a Zeva2. They could build all that into the Soliton because they already manage voltage and current. They have some outputs to use as drivers for the tach for current, and for the fuel gage as well for AH. That leads of course to the problem of AH synch.

    The solution there is to monitor battery voltage, which they already do, for a charge voltage level you would have to set in a variable. But then THAT requires the Soliton be on during charging. So it goes round and round. And ultimately the solution for THAT is unswitched 12v to the Soliton which has some background functions all the time, whether the ignition is switched on or not.

    Do you see where this goes.?

    Nevertheless, I would sure like the controller guys everywhere to take on the instrumentation role. They just have too much information to hog it all.

    As it is, they DO drive a fuel gage, but using battery voltage as the input - a very poor solution all around. The one thing worse than no fuel gage is a really bad one.

    AH, measured with hall effect, is good enough. It isn't "entirely" accurate. There are some drift issues and you really need to synch it to a full charge somehow. I like the way the Xantrex does that based on voltage because I can set a voltage that will only be seen at the END of a successful charge sequence. If I partially charge, it doesn't get synched but the cummulative errors are sufficiently small that you can go a week without synching and it will all be good enough, and certainly better than battery voltage.

    For now, we are stuck with things like the Zeva. I kind of like it though it is frustrating to set up. We are working on a similar system that will measure some split pack voltages and do the AH count and transmit all via bluetooth.

    I'm supposed to be receiving a device from Rechargecar that does the same thing via a USB cable. As long as it is isolated, that would work - it just means some wiring.

    We're doing a software program to display all of that. Eventually I want to port that to different controller serial streams, but each is different. Soliton 1 uses an IP packet protocol over ethernet. The Curtis 1238 uses an INVERTED serial stream with some other idiosyncracies. And the Rinehart doesn't actually supply the info I want on a simple serial stream.

    So chaos reigns in controllerville. Still, the controllers have RPM and temperatures in a handy format.

    Jack Rickard

  42. 3.65*.2A
    Thanks for the reply Jack. It gets worse. Apparently, he is stating that is all the supply can give! He was charging it with less than half that. Boiling a 200AH battery on 0.17W over an weekend. Wow! I would fit a compressing water jacket around it and heat the house on the cheap! How about boiling water with a penlight battery? A perfect campers friend!

    Just found and was reading another site/forum
    (Being English myself).
    Same old... Burned out cars... BMS hero's who are still experimenting on the field with everyone else's vehicles... Repeating the same old known quantities with the same old experiments... Realising the more problems they find on the road, the bigger and deeper the hole they have dug for themselves...

    What galls me is some people come back to them for more!!!!
    This is after mechanics prove their shunts are too weedy; the BMS designers admit they suffer EMI; wiring issues; reliability issues and me telling them you don't mix batteries and bare electronics in close proximity in case of venting near a failed BMS... Or anything that can ignite the gases!

    Eagerly awaiting for your next highly informative video to keep me quiet for an hour or so. :))

  43. Sorry, I can't leave what m1aws has said alone. He is mixing up what is actually posted and said. A poster on the TS group stated that he left a battery hooked up over a weekend to a CV power supply set at 3.65V and overcharged a battery.

    A different poster, me (David D. Nelson, AKA Gizmo), proposed that the cut off voltage used when charging should probably take into account what the ending current was. I'm charging my 2p20s 200Ah pack to 69.7V which comes out to 3.485vpc and that I'm undercharging by only something on the order of 1% based on some testing I did. The charger I'm using is a Zivan NG1 and that the ending current is less than 200mA which turns out to be 0.001C. I then suggested that maybe my charging to 3.485vpc at such a low current might be similar to charging to 3.65V at 10A or something and stopping.

    None of this had anything to do with a BMS. What I was proposing is exactly what Jack posted about a few posts above this one.

    Thank you, Jack, for stating what you did. It seems that since I posted it on the TS forum that some people chose to twist what was actually said.

    David D. Nelson, AKA Gizmo

  44. Jack:

    I replied to your e-mail to Seb on Feb 3rd, so if you still think you are being ignored as of Feb 5th then maybe check your spam folder?

    The programmable inputs, as described on p.6 of the manual, can be used for both analog and digital functions, so they do respond to 0-5V, but are also tolerant of up to 15V. When configured as a digital input they will treat any voltage from about 3V to 15V as "high" while 0V to around 2V will be treated as "low".

    Whenever an input is configured for a digital function (i.e. - "reverse", "motor temp sw.") I like to see a pullup or pulldown resistor between the input and 12V or ground, respectively, with the switch between input and ground or 12V, respectively. The Soliton1 inputs are weakly pulled down internally (100k) so putting the switch on the high side and using a stronger external pulldown (e.g. - 10k) is marginally preferable to putting the switch on the low side and using a pullup. Either way works, however.

    The "BMS LVC" function is not yet documented in the manual but it essentially cuts motor current to 0 when activated and as soon as the signal goes away it lets motor current ramp back up to whatever amperage the throttle is requesting at the user-programmed slew rate. If the BMS LVC signal latches when tripped then you will have just disabled your car. Whether that is ok or not depends on the customer, but suffice it to say that many BMS systems will turn off their LVC alarm output when the low-voltage condition goes away - if this is the case the Soliton1 will more or less limit motor current in a "closed loop" fashion as the weak cell dips in and out of LVC. This is the same way that the pack level "minimum battery voltage" setting works, btw (it doesn't shut down the controller when breached, in other words).

    The Soliton1 is not particularly accurate at measuring low currents and that is, I will admit, mostly because I didn't see much point in worrying over a few tens of amps out of a 1000 when I did the initial hardware design. It was only after about year in, when the beta firmware grew in sophistication and capability, that I came to regret not making the current sensing more accurate. The next hardware rev will be much improved in this respect, but counting Ah in the controller is still a bit of a Quixotic pursuit as there is no way for it to monitor the charging current.

    I agree that the "SoC" function in the Soliton1 is more or less useless. I've been lobbying to remove it for months now, actually, and now that you have skewered it in public it will likely happen. It does work tolerably well for lead-acid packs but not so much for LFP ones.

    I suppose I better go check your other blog entries for more comments, eh?


  45. Jeff:

    I can't find any earlier response in the SPAM folder. I did find some other comments by others. I would apologize for this, but I didn't do it, and don't know how to turn it off. If anyone knows how to disable Google's idiotic spam folder operation, I would love to hear about it. I can't find a way to make it go away, and it's throwing a number of comments into the spam folder for no obvious reason.

    I guess I get a little lost in your pullup/pulldown resistor description. We actually went into a really pretty pleasant "limp mode" with no input to the MOTOR TEMP SW set to ON. What I think I'm reading is if I connect that input to signal ground with a 10k "pulldown" resistor, that behavior will go away. And if I put 12v on the OTHER side of the switch, when it closes, the 12volts will put the Soliton1 into "limp mode." That would be cool.
    My assumption then is I could do the same thing with EITHER 5v or 12v from the Zeva2 by using Input 2 and setting that up for MOTOR TEMP SW also. I like your limp mode. Very smooth. The throttle trick limits acceleration, but you can actually build up to some speed over time. Yours doesn't seem to do that and I like it better.

    Again thanks.

    Jack Rickard

    We'll try it. Again, if you can describe WHICH input it needs to activate, 12v or grnd, that would be of interest.

  46. I'm curious if any body else has ordered parts from EVworks. I ordered the braided straps from them, and paid an $84 shipping to the US, then about a week after the parts arrived I got a second shipping bill from TNT in the amount of $42. I've been emailing both EVworks and TNT trying to find out why I got a bill, and it seems EVWorks shipping is only to the US and that TNT is adding a charge. So now I have $120+ for shipping a 5x7 padded envelope. Seems a bit excessive. EVWorks says that none of their other customers have been charged this added fee, and they are not responsible for it, but TNT insists that this is an additional import tariff that is the customers responsibility unless I can get EVworks to approve it (which they wont).

    Has any body else experienced this?