bms

[theskip1]

i was wondering, does the bms have to be conected at all times or can you conect it just for when its charging ?

 

[Blew it]

Lithium cells both charge and discharge at uneven rates, so yes, the BMS should be a permanent part of the battery.

 

[jerrysimon]

Except A123 cells... BMS what BMS

Jerry

 

[theskip1]

Lithium cells both charge and discharge at uneven rates, so yes, the BMS should be a permanent part of the battery.

bugger that means finding space thats already limited. i suppose it would not rebalance the battery just on charge up if i use shallow charge and discharge and use the bms if i know that my journey is a deep discharge run ?
thanks tk.

 

[NRG]

I don't use a BMS on my RC lithium cells but I do use modules to monitor low voltage when in use. The latest RC lithium cells keep their balance incredibly well, I also bulk charge them with dual power supplies and only balance them out on charge with some neat modules from Hobby City if they drift too far apart.

 

[theskip1]

I don't use a BMS on my RC lithium cells but I do use modules to monitor low voltage when in use. The latest RC lithium cells keep their balance incredibly well, I also bulk charge them with dual power supplies and only balance them out on charge with some neat modules from Hobby City if they drift too far apart.

could i do the balancing with a watts up or cycle analyst as iv'e read people do.

 

[NRG]

Not that I'm aware of...you'll need to either use an RC charger or multiples and charge each pack separately or bulk charge with a CC/CV PSU and use something like this battery medic from Hobby City to keep packs balanced at the end of charge:

HobbyKing Online R/C Hobby Store : Hobby King Battery Medic System 6S

I should add that tppacks.com will be releasing a BMS soon based on the Hobby City Cell log devices, maybe something to look out for in the next few weeks

 

[Grizzly Bear]

could i do the balancing with a watts up or cycle analyst as iv'e read people do.

You can get away with not using a BMS short term, long term it's going to cost you! it's going to cost you some new batteries! use a BMS don't think about not doing so, no matter what you read !
it's your money, a decent BMS is not expensive, use one ok!

Griz

 

[jerrysimon]

Or build your own A123 with no BMS required

http://www.pedelecs.co.uk/forum/electric-bicycles/5098-building-small-a123-battery-pack.html#post64491

Probably only any good if you want a small pack though you can carry a spare. A123 cells stay in balance very well.

Regards

Jerry

 

[theskip1]

You can get away with not using a BMS short term, long term it's going to cost you! it's going to cost you some new batteries! use a BMS don't think about not doing so, no matter what you read !
it's your money, a decent BMS is not expensive, use one ok!

Griz

ok i get the message.i got one with the battery already wired.will extend the wiring and try to stuff it somwere.
thanks tk

 

[Grizzly Bear]

ok i get the message.i got one with the battery already wired.will extend the wiring and try to stuff it somwere.
thanks tk

They do need a bit of air around them, the charging mosfet can get very hot, it is designed to do this, but it will not do your battery any good if this heat is transfered to it. Some insulating material between the BMS and the battery would be a good idea. Enjoy your LIFEPO4