# Battery Managment Systems



## 1clue (Jul 21, 2008)

On lead-acid batteries, a cell is one container of acid with plates. There are 6 cells in a 12v car battery.

I think most BMS implementations for lead acid will treat one battery as a cell, because to do otherwise means you chop holes in your battery as far as I can tell.


----------



## frodus (Apr 12, 2008)

well, point us to the BMS you're looking at. Some are for lifepo only, some are for lead. There's a difference.


----------



## gemmuj (Feb 22, 2008)

I'm looking at this one, but if anyone out there has any better ideas for a BMS please do share

http://elitepowersolutions.com/products/product_info.php?cPath=6&products_id=49


----------



## frodus (Apr 12, 2008)

thats for lifepo only...so no, it won't work with 12V 

it says on there, the voltage measurement range is 0-5V

what is your application though... whats the BMS going into? motorcycle, car, truck? 

Lee harts relay balancer is nice, it balances everything.

If you just want a display, paktrakr, if you want balancing, lee hart, rudman regulators or hotjuicelectric's BMS.


----------



## gemmuj (Feb 22, 2008)

What is lifepo? I've never heard that term before. I would like to use this BMS in a car with a battery pack of 12X12V batteries. 

Ideally, I am looking for a system which will be able to balance out the charge in all the batteries and also display to me the charge percentage of the total pack.

Also, does anyone know of a good charger for this application


----------



## frodus (Apr 12, 2008)

> What is lifepo? I've never heard that term before. I would like to use this BMS in a car with a battery pack of 12X12V batteries.


LiFePo is lithium Iron Phosphate... its a new lighter battery technology used in homebrew EV's and production EV's.



> Ideally, I am looking for a system which will be able to balance out the charge in all the batteries and also display to me the charge percentage of the total pack.


Thats 2 different systems. Monitors, and balancers.

For a monitor, Paktrakr will monitor battery voltages... but you need something else to balance the charge/equalize. 

For Balancing, 
http://www.cameronsoftware.com/ev/EV_BatteryManagementSystems.html

PowerCheq, Ruddman Regulators, Lee Hart's Battery Balancer, Lee Hart's Shunt Type Battery Balancer, BattEQ, Hotjuiceelectric BEQ1.


----------



## Libellule (Apr 3, 2009)

Others solution could be

For LiFePo4 battery

BMSBattery(*car*-*bike*)
http://www.bmsbattery.com/index.php?cPath=3

TPpacks(*bike*)
http://www.tppacks.com/products.asp?cat=26
The full topic for the design review of this concept by electric Eng.
http://www.endless-sphere.com/forums/viewtopic.php?f=14&t=5416&start=0

Don't like welding electronic, well guess what, here some site who will do it for you...
http://www.rechargeablelithiumpower.com/oscommerce2/catalog/battery-management-bmsvms-c-23.html

And have fun in your recherche!

Ciao


----------



## frodus (Apr 12, 2008)

Libellule said:


> Others solution could be
> 
> For LiFePo4 battery
> 
> ...


He stated in the thread he's using 12 12V batteries.... so those won't work.


----------



## bblocher (Jul 30, 2008)

The PakTraker is definately a good and low cost solution for battery monitoring. It also provides a little "fuel" gauge for the pack.

What type of 12v batteries are you using (flooded, AGM, Gel)? Amongst the long list you've already received for balancers, I also have a solution available you might be interested in.


----------



## gemmuj (Feb 22, 2008)

Thanks bblocher,

The PakTraker looks like a great piece of kit. Exactly what I was looking for.

What is this other solution that you spoke about??

Also, I am still trying to decide on the type of batteries to use. im trying to decide between Flooded Lead acid and LiFePo batteries. I am trying to wieght the own cost, wieght and suitibility arguement.


----------



## bblocher (Jul 30, 2008)

gemmuj said:


> What is this other solution that you spoke about??
> 
> Also, I am still trying to decide on the type of batteries to use. im trying to decide between Flooded Lead acid and LiFePo batteries. I am trying to wieght the own cost, wieght and suitibility arguement.


I made a simple shunt based solution for balancing my LiFePO4 cells. I had a lot of requests for higher voltage versions for LA batteries as well so I've added those. The link is down in my signature for the Volt Blochers.

I wish I had even more experience to give you advice, but so far I'm very pleased with the LiFePO4 cells. I have about 4000 miles on them so far. Not sure what your range requirements are but the LiFePO4 cells were really my only option.

Also, I have the BMS from Elite and I wish I didn't spend all that money on it. It's been my only problem with the entire build. If you decide to go the lithium route, still go with the PakTracker, Zivan charger and my next version of the Volt Blocher for LiFePO4 will be able to interface with the Zivan (as well as other smart chargers) to throttle back the current during high voltage as well. The current version just shunts and expects a BMS to be providing HV protection. I think this route will be about your cheapest LiFePO4 route that still gives you the protection you need.


----------



## gemmuj (Feb 22, 2008)

hi bblocher,

you battery balancers look very interesting. Does anyone know of a place where I can buy my LiFePo batteries? every where I have looked seem to be out of stock.

also, I am looking for the charger for these batts.


----------



## bblocher (Jul 30, 2008)

gemmuj said:


> hi bblocher,
> 
> you battery balancers look very interesting. Does anyone know of a place where I can buy my LiFePo batteries? every where I have looked seem to be out of stock.
> 
> also, I am looking for the charger for these batts.


http://www.evcomponents.com has the cheapest prices I know of. Most places don't carry them in stock and they have to be ordered (usually 2-3 month wait). Check these guys out though, they are working actually stocking the cells.

I know the Zivan chargers can be ordered for LiFePO4 and I've heard nothing but good things about them.


----------



## gemmuj (Feb 22, 2008)

hiya mate,

I have decided to go with Lead acid batteries as this is my first build and I would like to keep it as simple as possible.

what do you think of these Trojan batteries?

http://www.trojanbattery.com/Products/31-Gel12V.aspx

Are they any good? The sales lady kept on saying out Trojan are one of the best Battery manufacturers? is this true?

thank you


----------



## bblocher (Jul 30, 2008)

gemmuj said:


> hiya mate,
> 
> I have decided to go with Lead acid batteries as this is my first build and I would like to keep it as simple as possible.
> 
> ...


Trojan indeed is a high end battery manufacturer. I'm not the best to ask for which model is the best to buy. I recommend reposting your question again in this "Batteries and Charing" section but under a new title so you can get the best response possible.

However, you can expect to pay a fair price for these batteries. Keeping in mind how much capacity you really get out of any LA battery because of Peukert's effect, and the fact you still really need balancing on any series pak, I still recommend LiFePO4 for an EV. The life of the cells actually makes it a cheaper investment in the long run. You most likely won't need to modify suspension (I didn't even on my little car).


----------

