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Old 12-05-2009, 04:24 PM   #2691 (permalink)
The $500 Electric Car
 
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Originally Posted by jackbauer View Post
I found the igbt and freewheel were much happier at 8khz. My igbt is '05 vintage ex vfd. It did run at 16khz but i had problems with ringing at turn off. I just got an email from fran with v1.4 that , while untested , generates a 8khz pwm while running at 16mhz! Now I have the fun prospect of changing the crystal back to 16mhz while still in the car That said i'm building up another control board so may test it on that first. I'm running v0.9 in the car with great results i'd just like to be able to use newer versions of the code as it evolves. I don't know how or if the lower frequency would effect the mosfet design but mabey someone could run a test?
Better watch out Jack, you're almost out of gas.....

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Old 12-05-2009, 04:27 PM   #2692 (permalink)
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I've run it at 8kHz before in a controller, but not with this code. So did Joe. The caps got hotter slightly because of the increased ripple, but the mosfets ran cooler. Also, the controller was in my back seat, so I could barely hear a piercing tone that felt like my ears were ringing. hehe

Edit: vpoppy! I was going to say that! You pickle! Oops, I still need to send you a control board and power section.
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Old 12-06-2009, 09:29 AM   #2693 (permalink)
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Battery management and the Open Revolt controller

I have been involved in a open source lithium bms project for over a year now. Probably the hardest and most crucial thing is how you use the system to prevent cells being damaged by over discharging them. The only way to do this with most controllers is to reduce the throttle input. It's tricky to do though as you don't want to abruptly shut it off as that could be dangerous but you do need to keep reducing it at a level that prevents any cell going below it's allowed minimum voltage.

So this project presents an opportunity to solve this problem. It would require a input to the ATmega168, but I understand that a few are available. The idea is this, we have a input for low pack voltage. This is supplied by the bms, but it could even be useful for lead acid conversions, all you need is a signal when pack voltage drops below a certain level. When the controller receives this signal it calculates battery amps, which I believe is already done in software, and sets a new value for maximum allowed battery amps to be say 10 amps lower than the present value. So if you are drawing 200 amps from your battery pack when the bms signals a low cell warning, the controller will reduce this to no more than 190 amps. If this still doesn't put off the alarm then it drops to 180 amps, etc all the way to 0 amps. Of course backing off the throttle will also put the alarm off, but the controller will remember its max allowed battery amps and will never allow battery amps to exceed the maximum until it is switched off. Only then will it reset back to it's default value.

The effect when driving is that the car will start to gradually slow down when the battery pack is nearly depleted. By taking it easy you can maybe gently nurse the car to your destination, or at least a place to plug it in. But it will never allow you to over discharge a battery, which shortens the life of lead acid and murders lithium cells.

BTW, link to the bms project I mentioned can be found here;
Battery Vehicle Society :: View Forum - All things battery related
Look for the top 3 sticky topics, BMS General, BMS Hardware and BMS Software.

Also, where can I find the latest controller software?

Greg
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Old 12-06-2009, 01:23 PM   #2694 (permalink)
The $500 Electric Car
 
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vpoppy! I was going to say that! You pickle! Oops, I still need to send you a control board and power section.
It's true what they say: Great minds DO think alike

Ok, it's Christmas and all, and if I'm gonna get free stuff, I wanna donate to the rickshaw and buy something. Do you have to MAKE the isolation strips, or do you have some premade? I don't want you to have to spend time on something. Or maybe the silver epoxy? Hey, that might work to fix my rear window defroster too....Anyway, that way you'll get my address and all.....
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Old 12-06-2009, 03:16 PM   #2695 (permalink)
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Oh, I'll send you some isolation strips for free too. They are made already. I got me a whole big dang pile of 'em! Buy the silver epoxy. It's cheap. I think we have enough for the rickshaw now! Some people ordered a control board and power section a few days ago, and even 2 people ordered kits! ya! The freakin mosfets aren't available until the end of january, though. Makes me mad...
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Old 12-06-2009, 03:54 PM   #2696 (permalink)
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Quote:
Originally Posted by MPaulHolmes View Post
Oh, I'll send you some isolation strips for free too. They are made already. I got me a whole big dang pile of 'em! Buy the silver epoxy. It's cheap. I think we have enough for the rickshaw now! Some people ordered a control board and power section a few days ago, and even 2 people ordered kits! ya! The freakin mosfets aren't available until the end of january, though. Makes me mad...
Man Paul, you are so generous I feel like the Grinch compared to you
Thank you. I'll make sure not to have TOO much coffee before I start soldering.....
I think YOU get to pick the name of the under 500 dollar freeway capable Toyota.....
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Old 12-06-2009, 04:18 PM   #2697 (permalink)
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Better watch out Jack, you're almost out of gas.....
Where i'm goin' i don't need gas I'm doing a budget build on the second control pcb. Lots of compromises and component substitutions such as 2k2 resistors instead of 2k I need a test bed for the new code and a basis for another igbt based design.
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Old 12-06-2009, 04:40 PM   #2698 (permalink)
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Paul, We should have a naming contest! hahaha. How about the
S.T.I.N.K.Y. D.I.A.P.E.R., or the

Super, Terrific, Incredible, New, Krazy-good, yellow (you must make it yellow for this name to work), Dang, Inconceivable, Amazing, Perfect, Electric Racer!

Jack! 2.2kOhm is no problem. One of the 2k is just a pull up, and the other will make the throttle range change a tiny bit, but that doesn't matter anymore either. ya! That will probably shave off like $500! ya!
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Old 12-06-2009, 08:39 PM   #2699 (permalink)
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Quote:
Originally Posted by MPaulHolmes View Post
I think we have enough for the rickshaw now! Some people ordered a control board and power section a few days ago, and even 2 people ordered kits! ya! The freakin mosfets aren't available until the end of january, though. Makes me mad...
Hi,Paul. Just wanted to let you know I got the end pieces,Thanks. Was wondering how the rickshaw drive is going. Sounds like it went well. Shipping
may be expensive, I dont know. Am ordering the power board, and will be
collecting parts as I can. Bad luck about the mosfets, the last time I looked
the caps had a lead time on them too. The rest seems to be available,though.
Watt
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Old 12-06-2009, 09:45 PM   #2700 (permalink)
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There's a lead time on Capacitors, since I bought 200 of them! hahahahaha!

We're not shipping a rickshaw to anyone! That would be really really really really expensive. We're just sending the money for it. We're also going to buy some chickens (they lay eggs!), maybe a goat, and a couple other things. Then the people (Dalits for the most part: Dalit - Wikipedia, the free encyclopedia) will get all their stuff, hurray, the end. haha!

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