BMS testing

[Lurkin]

I've bought a Chinese BMS to play with until my frame issues are sorted out. Given that there's little known of its origin or capability, it makes sense to test it silly before committing it to a decent sized pack.

I've been looking on here (yes, using the search function) for a simple 'how to' for BMS feature testing. I'm struggling to find one. Yes, there are long and complex threads on here involving BMS, but I think a quick and dirty how to would be of great value to people new to BMS. I'm thinking tools, tests, techniques, things to watch out for, how not to burn your house down.

Features of the BMS in question:-
- 13S 48v with balance function for 3.7v lithium ion batteries
- Continuous working current: 40a
- Maximum discharge protection circuit 100a
- Dissipation Power: less than 20uA

Tables aren't posting properly from the ad. The BMS is this one here: http://www.aliexpress.com/item/Free-Shipping-48V-40A-BMS-13S-48V-54-6V-li-ion-battery-BMS-PCM-40A-continuous/32283657890.html

The plan to so far:
- obtain 13x junk 18650s and individual cell holders
- attach cell log 8s
- apply a small current at 54.6v to charge, watch and see what happens

Questions:
- Can I do this with a power supply (with variable voltage and current so I can control it) rather than an actual charger and switch it off when the cells are at 4.2v?
- If so, how does this work with the balancing cycle? do I need to reduce the current further but maintain the voltage?
- what am I missing here?

If I can get some help figuring this out, I intend to start buying cheap BMS and testing them, posting up the data and making an entry into the wiki with the testing plan for everyone's benefit to be able to get affordable, some what tested BMS.

 

[kdog]

Reviving this old thread, I don't think lurkin will mind if I do...
I have a number of used bms's and more coming in all the time as part of my casual ebike work. Mostly they're from Ezee batteries, but others as well.
I'd like to be able to the test bms function, so I know what state they're in.
First... Does anybody know of a bms testing device that is commercially available?
I've seen some stupidly advanced and expensive ones but none in the DIY end of town.
I don't think they exist...
Which brings me to my second and main part of discussion.
Earlier in the year I built a test bed for up to 10s bms's. It was simple and didn't get it finished but it proved an idea. I hacked up a 10s1p battery with sensor leads and a halogen light load. I popped a pot on each sensor lead which served as a V divider.
I was able to test each channel on a bms by turning down/up the respective pot tripping the bms.
Unfortunately, if I turned the pot too far I burnt the channel out. I got busy and it went on the back burner, but i want to revive the testing because I've got more bmss in.
I'm a hack so any help is appreciated!
I'm happy using a battery as a power source- ive got heaps of junk cells lying around, and one test unit already made.
I'll need a way to prevent the channel from blowing.... I figure it shouldn't be too hard-just limit the V drop on each channel by adj the R ratio.
Other features I'd like to test are:
er channel bleed function. im thinking a small led in line with the pot would show me if bleed power is being drawn. This will also tell me if the channel is pathologically open and draining cell groups down.
: V measurements on each channel. Short of buying ten small v meters, I guess I could just use a dmm and plug it into the individual channel I'm testing. Is there a more elegant way to do this.
: LVC... Is this only a function of the summed cell voltages or is there a separate pack voltage measurement. I ask bc I wonder if I just turn all the sensorV down will that simulate the effect of a flat battery.
Anyone got any advice? As I said , I'm a hack so any guidance will probably help!