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We were recently featured in a story in our local paper, the Southeast Missourian. Nice story. Thank you guys.
We've been in quite a struggle with our MES-DEA 200-250 Motor. On assembly, we found a vibration in the drive train. When we removed the drivetrain from the vehicle, we found a huge crack almost all the way around the end plate.
We appealed to our supplier, Victor Tichonov of Metric Mind and the manufacturer, MES-DEA for relief. They threw us under the bus but big time. No support at all.
We opened the motor and found the end plate was 6.22mm thick of CAST ALUMINUM. An eggshell. Hopelessly underweight to mount this motor with.
Our Friday, March 26 video describes the fix. We had to have an entirely new endplate machined for this motor. Cape Precision Machine came to our rescue with a superb job on this end plate and we finally got the wheels spinning on the 2009 Mini Cooper. Hopefully, we'll have it out for a first drive this week.
We also include in this week's news show a walk through of Tim Catellier's 2000 BMW Z3 conversion. Tim did a great conversion of this car with a Zilla controller and Netgain 11 motor.
Jack RIckard
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Jack,
ReplyDeleteYou mentioned that the batteries in your speedster seem to be getting closer into balance rather than further apart. FWIW, I only see three possibilities with a series pack of batteries and no BMS to speak of: cells stay the same relative to each other, cells drift further apart, cells drift closer together. With no info to go on I would guess each outcome would be equally likely. If I consider entropy I would guess drift apart is most likely and appears is what most people assume will happen.
If your batteries are drifting closer together then I was wondering what the possible mechanism is. Have you or anyone else measured the internal resistance at different points of SOC? I'm wondering if the resistance increases as a cell nears 100% SOC. If it does then maybe that is what is causing your cells to drift closer together. You may be charging just close enough to 100% SOC for this to work.
FWIW, I have a non-ideal charger to charge my TS-LFP pack. It is a Zivan NG-1 programmed for T-875 lead acid batteries. I have merely adjusted the voltage pot so that the charger will completely shut down when the pack reaches 71.5V. I need it this high so it won't time out before the pack fills up. This translates to 3.97vpc. Periodically I monitor the cells at the end of charge and I rarely see the BMS shunts turn on on any of the cells. My BMS shunts turn on at 4.00vpc and it is a very sharp turn on so no shunting happens unless a cell hits the top. If it does it only shunts 500mA or less.
My BMS doesn't bring cell voltages to a common point like the cell logger8 or what ever it was that shorted on you. The signal bus is powered independently from the 12V system so it is significantly less likely to have a short between cells.
David Nelson
Hi Jack,
ReplyDeleteI'm quite puzzled from this MetricMind-MES/DEA situation, Victor used to have spotless name in the EV scene for years, he helped me during that infamous Evisol scam inverters affair 2yrs ago. I gather he was used to deal with the real pros like Siemens and Brusa, so he expected the same from other swiss brand "MES-DEA" and that's where without first hand knowledge he fell into the trap with sub standard supplier. Now, thanks to your dilligent diy approach, we have found out it's bordering on crap quality brand, perhaps good enough for golfcarts.
On another note I really appreciate your stamina to risk not small amount of fin. and time resources into trying the new stuff. Especially, liked your water cooling sub project for the AC Curtis inverter.
Also, liked the Yazaki charging acess. equipment, I'm wondering do you plan to prototype your own driving *circuit (based on released specification) or buy it from EVcomponents - as I assume they will be onto this since they used to sell 3rd party adapters from "Tesla Roadster Foundry" already.
*I don't have the most recent SAE document at hand, but if I recall it correctly, the earlier versions described the circuitry driving these various resistors for charger-EV communication in great detail.
Hi Jack,
ReplyDeleteHope everything is OK, we've been hanging out for your "weekly EVTV" news, maybe your just on holiday
Simon (New Zealand)
Hmmmm, MES-DEA taken to your kneecaps Rick?
ReplyDelete"you have been warned"
Hope all is OK, like Simon above I'm looking forward to your next update.
Dave J (also from New Zealand)
Think it might be more than just kneecaps, Victor & MES-DEA mean business!! lol
ReplyDeleteSimon (New Zealand)
Hi Jack,
ReplyDeleteThis is only my second internet post.
Hope all is well. My comment is in reguard to cooling the power controller.
Have you considered a thermoelectric unit?
I would enjoy your comments on the pros and cons of thermoelectric units.
Reguards Mark
Hi Jack
ReplyDeleteI came across this little clip from the UK of a chap who did a fairly convincing job of converting a Mini. Hope you like it.
http://www.youtube.com/watch?v=scMd_5C-vOg&feature=related
Cheers
Nikolaus
Hmm. I should be more attentive to the blog, that is obvious.
ReplyDeleteOn cooling. Yes, I've played with thermoelectric/peltier devices. The problem is that they are all about the heat sink. So making them the heat sink doesn't make much sense. We can just heat sink the controller and be done with it without the expended power of the peltier AND it's heat sink.
On J1772 and other engineering developments. We are not component suppliers. Unfortunately, in somecases, what I want to do has to be fabricated because it does not yet exist (ie Curtis chiller plate).
When we do that, we would normally give away the design or give it away for a small royalty perhaps. This is the basis of Speedster Part Duh. I'll receive a modest royalty on each car they develop. In the case of the Chiller plate, we have basically allowed Cape Presicion Machine to offer them to anyone who calls without any fee - to keep the cost low.
We would expect EVComponents to do a J1772 kit for electric cars. If they are slow to do one, we would design one and let them make/sell it. But I think they'll be all over it anyway.
On the BMS's, I think you are overcharging at an average 3.87 v. I would like to see you 20 or 30 points below that. I find shunts absolutely alarming unless they are operating in front of you. And I find the whole Zivan schtick unacceptable for electric vehicles.
Again, you don't really want to cut off your charge when it reaches a voltage. You want to transition into a CV stage where the cells are held at a specific voltage and continue to absorbe energy until they will accept no more at that voltage.
As to drift, entropy by definition evolves toward the norm, and almost never to the edges or extremes. This is true of all systems. If there is a move toward divergence THAT has to be powered or driven by something. Like a BMS. Entropy always moves toward the mean.
Jack Rickard