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We've been in contact with a somewhat interesting pair who are on a worldwide tour in an electric car.
Hjalte Tin and Nina Rasmussen left Compenhagen on June 25 on a 41,000 mile trek in a Nissan QashQuai converted to electric drive by AFUTURE Electric Vehicles They are driving around the planet on a year long odyssey and plugging in where they might.
This morning, they are at a campground in Poplar Bluff and advise us they could use a charge and a place to stay. So we expect them this afternoon and we'll have them join us for dinner.
The AFUTURE Nissan Qashqai is an SUV converted to elecric with a range of up to 250 km. Recall that this was the car that burned up the ferry in Norway. I hope it doesn't do in our shop. BMS all over the place driving two helpless Brusa chargers. It will be interesting to have a look at the configuration.
The couple is detailing their tour on a web site called MotoMundo
They are on their way from Dallas to St. Louis and someone from our own Gateway EV has arranged for their charging there. Then on to Detroit in time for the Detroit Auto show.
I rather gather that AFUTURE is funding all this to demonstrate their cars. They seem to be trying to raise as much media and press attention as possible and doing a fair job of it. I would as soon paddle a canoe around the world but it is interesting that they are doing it I suppose.
In any event, we look forward to an interesting visit. We'll let you know what we find. Maybe we can shoot a segment or something for next weeks' show.
Jack Rickard
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I have taken a good look at the brochure for the AFuture vehicle and it looks pretty nice!
ReplyDeleteWhat struck me first was that it has not one, but TWO brusa chargers. I don't know if you have checked Victors prices lately but it looks like the electric Qashqai may be a bit out of my price bracket!
I for one will be VERY interested to see what and where the batteries are. Some mention is made regarding the batteries being "large format" so it would be great to find if they are CALB or Thundersky.
I do have a question regarding the capacities of the batteries over time. Most of your vehicles have basically new packs with exception of the original speedster - which is now getting a new pack anyway - so you may not yet have given any thought to the matter of battery life in respect of mileage capacity, despite the discussions of what to do to maximise it.
As you have mentioned many times, voltage does not give us a reliable estimate of how much capacity is left in our cells, so we must therefore track AH in and out. Many of us will inevitably face the reduction of our packs overall capity with time and hence what was once a safe 80% DOD may eventally exceed the capacity of our batteries.
Therefore, what (if any) adjustment to the "fuel gage" or Xpert pro will you make over time to provide for changes in the battery capacities and how would you envisage going about determining how the batttery capacity is holding up? I realise that the life will vary wildly with many variables like recharge frequency, DOD, temperature etc, etc, etc... but I wouldn't want to kill them because I forgot to allow for diminishing capacity.
Would running the car down to a known voltage (i.e. 3.00v/cell) maybe every 6 months or so, and recording the AH required to recharge, give us a reasonable indication of the current pack capacity WRT to when it was new?
I look forward to your next video with baited breath - thanks for all the hard work Jack.
Nick Smith
I hope that Mr. Rickard kept good diplomatic relations with the Nordic countries! ;)
ReplyDeleteWhat is it with people who are so mad about charging up to the nth degree at the highest rate possible? This maybe of interest:
From a blog that insists on BMS.
A few posts on how they fix swollen cells. They even have a new BMS! This one is not backwards compatible with the old. What is wrong with the old BMS's I wonder? hehehehe
However, they do insist end plates and straps to stop battery swelling. This I like.
The idea of holding them rigid when the car is taking a kicking in the shock absorbers.
http://gwl-power.tumblr.com/
Hi Andy,
ReplyDeleteI do hope you know more about EV's than geography ;-)
Martin.
Martin: I don't get it.
ReplyDeleteJack: keep up the good work. The more information you provide the easier it will be for everyone else to decide how to build their own EV.
Rasmus
Rasmus,
ReplyDeleteI did read Andy's entry as if gwl-power was located in "The Nordic Countries".
Martin.
Hi Martin.
ReplyDeleteI made a jest for Jack to be diplomatic when the Nissan QashQuai EV, (resplendent with a veritable birds nest of wires and electronics atop the batteries), Comes rolling into his garage for an overnight recharge. lol
Must be said; a round the world trip on an EV does deserve recognition. I hope it becomes a documentary for TV.
The Blog that speaks of fixing blown batteries and talks of a new BMS... Should I have posted that separately for clarity?
Martin,
ReplyDeleteMaybe you should review your geography. Denmark IS a Nordic country: http://en.wikipedia.org/wiki/Nordic_countries
Alex
Tesla released some videos today
ReplyDeletehttp://www.teslamotors.com/blog/tesla-vehicle-engineering
I don't see that the radiators are that much smaller than even an ICE car.
Some of the sheet metal around the inverter/motor looks like they had a fit problem like the cooper.
Not quite a working model yet.
But it does look good. Too bad I don't think I can work out the Tesla pays for my Tesla plan. I had thought of that but don't have the betting money.
Jack,
Can you discuss how the option/lockup cycle works? Vis a vi, when will the people working on the bet on the drop after lock up principal be out of the picture? I know there are witching hours and options have expiration dates. Is there a 30 day, 90 day, 120 day window?
Nick Smith.
ReplyDeleteIf you are reading this. Have a look at Jacks Video for Nov 6th 2009. I think I read battery capacitance is ~<5% somewhere. Can't go wrong charging within the battery with the smallest capacitance, when the chance to bottom balance comes your way.
Hey Martin, I wrongly assumed these batteries on fire should not be put out with water.. Thinking these batteries would burn like a magnesium fire. Happy to be corrected. I'll never claim to be very knowledgeable but am sticking with Nordic, lol.
Alex: I do know that Denmark is a nordic country - I live there ;-)
ReplyDeleteI did read Andy's entry as if gwl-power was located in "The Nordic Countries". Which it isn't since it is located in the Czech Republic.
Andyj: I haven't read the blog. But just browsed through the headlines. A link would be nice :) And "Yes" you can cool a fire in a lithium battery in order to stop it. But people are reluctant to pour water on an electrical fire... Even though it is quite safe to use a water spray on low voltage installations (including batteries), if the water is normal tap water, which is a poor conducter in the first place.
Martin.
Martin.
ReplyDeleteI did send a link. Don't know how you missed it.
Re-sent :)
http://gwl-power.tumblr.com/
Andyj - I watched the nov 6 video again and to be honest don't understand your comment about the battery capacitance.
ReplyDeleteI will try to paraphrase myself and rework my original question.
If battery life is supposed to be 3000 cycles (defined as when they reach 80% of original capacity) how will I know?
If the expert pro is programmed to switch to daughter mode at say 120 ah used from a 180 ah battery (giving a 30% margin to empty), what happens when my battery now only has 144 ah capacity? The expert pro will now néed to switch to daughter mode at 100 ah to maintain the 30% margin.
My question is then - what method do I use to determine the batteries actual capacity at any given time during their life and how often one would need to do this?
Nick Smith
Andyj
ReplyDeleteI don' see why everyone misunderstood your first post - if they read the blog entry from Jack and then yours it is totally clear to me that you were referring to the qashqui in your first paragraph.
Hi Nick,
ReplyDeleteFirstly, Must tell you. I don't have an electric car. Not even one cell to play with. I'm still checking out the market for the best play. I owe just about everything I know to this hard working team here.
Battery charging/discharging.
Keep it simple, keep out of their limits. Then you should never reach this 80% dod. Maximising your investment to the last penny, watt or metre can cost a lot of money in reliability. Ironic I know.
If your weakest cell is 5% down against the strongest. Then its 2.5% down on the ends. Its nothing!
When cells go all awry its usually because something is on them nicking a charge and doing its own thing. These batteries are essentially pea's in a pod It's electronics that use multitudes of +-10% components! Notice how the BMS guys go on about "battery self discharge". It's their electronics that is doing it!
It is good to check your cells if low and before charging. If any are low then you can boost the lowest ones a little. Then that should be it for maybe a fair while.
Not all batteries are the same mainly due to their physical position = humidity and temperature. That can affect up to 20% capacity.
I have no idea of the equipment you refer to.
You "can over charge these batteries" if it is not too long, above 3.75V nor too high a temperature.
Bottom balancing stops any batteries being forced into a reverse charge if they all go down to 2.8V at the same time its not so bad. Its game over when any are forced into reverse.
I'm still tempted to the idea of 30Amp wire tagged to every, (or fourth) bus bar leading to a central checking point for each box. At the same point, a top up could be offered. A single bolt centrally drilled to take a temp probe on a battery hot end (anode?). The batteries boxed from the weather and the wiring properly tied up. Birds nests are a car killer.
Maybe Jack can improve or add to that. He won't buy to the extra wires I opine. Thats for sure!
Martin just read my earlier post too quickly. I forgive him; he's a nice fella.
Nick:
ReplyDeleteFirst, it would be a gradual problem. 3000 cycles is about 10 years around here. So I haven't precisely had to deal with it.
We "manage" our packs based on several pretty rude meters.
First, we have an odometer. Pretty quickly on in a car, you have a pretty good idea how far everything is. While driving style varies from person to person, your's doesn't much. You'll get about the same mileage drive to drive but you will notice differences in season/temperature.
Second we have a voltmeter. It is most meaningful of course at the stoplight with no load. It always declines as you drive. And this decline accelerates as you move down the discharge curve. If you will simply note the voltage routinely when the car stops for traffic or a light, this becomes second sense. And you will quite quickly gain a sense of where you are in your pack IF you have something to "calibrate this knowledge to" - your AH meter.
The AH meter is of course really your "fuel gage". But it is rather interactive with your voltmeter. I notice a signficant decline in voltage against AH in winter driving below 0C than during the summer for example. I basically have "less capacity" much more realistically and presently than in your 3000 cycle scenario.
Beyond 80% discharge, and we actually DO go there quite a lot, the voltmeter virtually becomes a fuel gage. It is quite useful, and of course on some drives alarming. The voltage quickly falls off as you pass 90% and is plummeting pretty good at 95%.
AH and volts are your coinage and range is of course the need. But when you are talking about 3000 cycles, that's a lot of time to get familiar with these. There are a lot of concerns with these cells, but that's the first time anyone has brought up what happens then. The bottom line is we've never gotten that far. But it is kind of a non-problem. By the time you drive 3000 cycles down to 80% of original capacity, you've driven the car so much that you'll have a sense for exactly where you are in the pack all the time.
But the inputs are voltage and amp hours and those two numbers will quickly get you smart.
We just blew up a little DC-DC converter powering my Xantrex AH meter on the Mini. I feel like I'm flying blind. But the voltmeter - a separate meter, still works quite well.
We also usually have some sort of indication of "pack balance". This means a very different thing around here than you see discussed on the forums. We basically measure one half of the pack's voltage and compare it to the other's in various ways. On the EVISION in our first build, this is an LED array that displaces by the amount of voltage difference between the two packs. This is basically our "health/sanity" check. The top half of the pack should be at the same voltage as the bottom half of the pack, all the time - at rest, under load, whatever. If one half indicates something different than the other half, we have a problem Houston. That would indicate a cell that is bad or going bad. For example, if one cell sags much more than the others under high current loads.
We really don't have any cell failures or problems in any unaccounted for sense. I have lost a few when driving to extreme range and it turns out for good reason. We've had "parasitic loads" basically bleeding off AH very slowly but over long time periods of months, from instrumentation we've put on some cells, but not all or others. We've kind of learned to avoid that.
The basic rule that has emerged over two and half years is "First Do No Harm." Every problem has been traced to some very well intentioned effort to "manage" the cells. But that effort itself damaged them. Had we just left them alone, they would have been fine. Something as innocent as powering a Xantrex from the first ten cells but not the others. A Cell Log 8S that was plugged into 16 cells (actually two Cell Log 8S) for two months. These are TINY loads and VERY innocent devices. Still disastrous over time.
ReplyDeleteWe've even found frame ground leaks of our packs through el cheapo voltmeters and have learned to use 12v/12v DC-DC converters to power them just to isolate the pack from the 12 volt system. You just don't think about this, but it poses a potentially serious issue.
Having dealt with this over the last going on three years now, and with kind of unlimited test equipment and the ability to run experiments quite off the car, I am well aware of why some of these guys think you need a BMS. I'm sure it looks like magic to them and the cells are just randomly drifting around. They're not. They themselves are causing it. But a BMS is MORE intrusion and mucking about, not less. It complicates the entire machine heroically. And mostly just moves the problem around.
These cells are remarkablly robust left to their own devices. T hey more you screw around with them, the more finicky they become.
1. Don't overcharge them.
2. Don't overdischarge them.
That's the trick. Piling on a lot of equipment to prevnt those two scenarious is a serious mistake. And of the two, not overcharging is the most serious. If you overcharge these packs signficantly, they will burn like the seven blazes of hell, taking the car and anything it is in with it. About 518F, and these cells go into thermal runaway and it becomes quite a fire.
A lot of the BMS work is basically trying to get a bad charger to be good. You need a good charger matched quite to your pack to start with. And you don't need the BMS at all. THere are some well and good reasons why it would be heroically unlikely that you'll see a "good" BMS emerge from all this. And if they fail, and the charge is not terminated, the results are truly spectacularlly disastrous.
jack Rickard
Jack - thanks for the detailed response. I suppose this is going to be one of those long term experiments that will maybe come up in your Friday show of May 15, 2015 "Tracking AH Capacity with Age".
ReplyDeleteMay I ask how you blew up the Xantrex DC/DC?
I connected mine backwards to "see what would happen" and I can tell you it made quite a bang and left a scorch on my workbench that is still there to this day!
Blocking diodes on contactors are pretty exciting too when connected backwards with no fuse!
Nick Smith
Nick:
ReplyDeleteYou know I'm not certain at this point. It was the SECOND one we've blown up, but this one sounded like a bomb. Disconnected battery pack reconnected did it both times. I'm a little worried about a ground leak of our pack but Im not finding anything.
We're going to a 12-24v stepup converter for our Xantrex power. We'll use our normal 12vdc converter as the source and just pump it up to 24 volts for the Xantrex.
Jack Rickard
Curious... Why 24v for the Xantrex? I know it will work up to 35vdc, but I've got a Xantrex LinkPRO that I power with an inexpensive, isolated DC-DC converter (a Cincon from Mouser) off my 12v system. It stays on all the time (ignition bypassed circuit) unless I throw the 12v battery disconnect, and the setup obviously doesn't drain the traction pack.
ReplyDeleteSorry, meant to add it's a 12vdc->12vdc converter. LinkPRO seems fine with it.
ReplyDelete