HELP - designing BMS for HEV using 40Ah batteries

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hybridsae
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Joined: Fri Jan 06, 2012 1:10 am

HELP - designing BMS for HEV using 40Ah batteries

Postby hybridsae » Thu Jan 12, 2012 3:15 am

Hello to those interested in helping me,

I am an undergraduate Electrical Engineering student at Lakehead University. We are designing a Hybrid Electric Vehicle (crappy website link: http://hybrid.lakeheadu.ca/webcam.html) and I stumbled upon the battery vehicle society website and think it would potentially be extremely useful, but it is also extremely overwhelming as well. My group is in responsible for charging 40Ah lithium-polymer batteries from scratch as part of a whole HEV system. We do have access to a microcontroller which will be integral part of our design, but we are all brand new on lithium batteries. Our problem so far seems to be designing a constant current regulator to be able to charge the batteries at constant current (very high current). Right now we were thinking about having the whole bank in series and charging them with a balancing circuit in between the terminals of each battery integrated with the microcontroller.

ANYWAYS, we really don't know much (beyond a few basics) even after researching for a couple months and was just acting kindly if you could aid us or send us in the right direction to design a system that would be able to do what we are trying to do and that is charge and balance our 40Ah batteries. We also have a smaller 10.8V 5200mAh battery pack with 8 cells from a laptop and was going to charge that first to be able to start small scale and work our way up possibly but its even difficult really to find circuits that will help us do that. So please just let us know if you can be of assistance.

The main thing is though, we also cannot just purchase a charger/balancer, but we are supposed to design the system.

Thank you so much for you time and consideration,
Paul
(and the rest of the Lakehead Hybrid Vehicle SAE team)

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retepsnikrep
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Re: HELP - designing BMS for HEV using 40Ah batteries

Postby retepsnikrep » Thu Jan 12, 2012 5:26 am

See my reply via PM. All the info you need is in these BMS threads.
Give yourself a week to read a major chunk of it. Then ask relevant questions in the specific threads.

Peter
Regards Peter

Two MK1 Honda Insight's. One running 20ah A123 Lithium pack. One 8ah BetterBattery Nimh pack.
One HCH1 Civic Hybrid running 60ah A123 Lithium pack.

azmeer2601
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Joined: Sat Mar 30, 2013 5:59 am

Re: HELP - designing BMS for HEV using 40Ah batteries

Postby azmeer2601 » Sun Mar 31, 2013 4:06 pm

Hi guys,

Im newbie here..anyway I amm a final year undergraduate student in one of the university in malaysia. Im currently doing BMS as my final year project. I am focusing more on passive type of cell balancing. However, i have problems to start on designing the circuit. need some advice on this matter. Really appreciate for your help. Thank you.

GregsGarage
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Location: Galashiels, Scottish Borders
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Re: HELP - designing BMS for HEV using 40Ah batteries

Postby GregsGarage » Sun Mar 31, 2013 10:05 pm

As Peter says;

retepsnikrep wrote:All the info you need is in these BMS threads.
Give yourself a week to read a major chunk of it. Then ask relevant questions in the specific threads.

Peter
Greg Fordyce

Daewoo Matiz
http://www.evalbum.com/4191

Beemer
Posts: 294
Joined: Sat Jun 04, 2011 12:10 pm

Re: HELP - designing BMS for HEV using 40Ah batteries

Postby Beemer » Tue May 28, 2013 8:08 am

You didn't even state what kind of lithium pack you are using. They have an assortment of charging, discharging voltages, rates, temperature and safety issues, you name it.

Apart from that, if you bottom balance, never over discharge/overcharge, you don't need a BMS. Like you do with a lead acid pack.

http://www.evtv.me/


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