Looking into installing a BMS

[mistercrash]

I have been bulk charging everyday with a balance charge once a week to monitor how my cells are doing. It's working but after doing it for three years, I am looking for an easier and safer way of doing it. A BMS is the answer but which one.

Here's my set up:

- Heavy scooter with heavy guy http://i177.photobucket.com/albums/w202/mistercrash1964/Motorino/moped1_small.jpg
- 16S20P battery made of Makita Konion cells. split into four batteries for easier install in the scooter. http://i177.photobucket.com/albums/...ries and chargers/new_konion5_zps35c0b8ab.jpg

When I had a Cycle Analyst on the scooter it often showed close to 100A on acceleration from a stop and more than 80A going up steep hills. going at 50 km/h on flat ground is just under 40A.

I was looking at Bestek Power BMSs for 16S and there are 80amp units and then it jumps to 250amp units so I was considering this one, is it overkill? http://www.bestekpower.com/592v16spcmbmspcbforli-ionli-polymerbatterypack/BMS-D170.html

Thanks
Ray

 

[Nobuo]

That BMS would perfectly work, but you could have the same performance with these 90A and 100A BMS

http://www.aliexpress.com/store/product/16S-60V-67-2V-Lithium-ion-18650-battery-lithium-polymer-battery-BMS-with-90A-constant-discharge/1379203_32219214427.html

http://www.aliexpress.com/store/product/16S-60V-67-2V-lithium-ion-battery-BMS-with-80A-constant-working-current-for-li-ion/1379203_32307070606.html

 

[mistercrash]

Thank you for the links, but from what I read in here, Bestek BMSs work very well and I would rather try one of their BMS. I am just not sure how to buy one, I sent an email asking them what the procedure is. Waiting for a reply.

Thanks
Ray

 

[dnmun]

yes, that is overkill. go look at the 16S D166 and see if you can live with that max current. buy two of them so you have a backup and it is cheaper shipping per unit that way.

if you can talk someone else into joining you on your order, then pile them all into one air freight and then reship the extra one to someone else using 1st class mail like i did.

i use the D131 but i go 24S for lifepo4 and 21S for lipo but i use the 24S BMS for my 21S lipo. for my ZENN car.

 

[mistercrash]

I was hoping you would chime in. Thanks dnmun. Is the D166 limited to 50A all the time? Will it make my scooter sluggish from a dead stop and slow down considerably going up hills? Or can it handle double the current it's rated at for a few seconds?

Thanks
Ray

 

[dnmun]

with a BMS it does not slow down, the output current is shut off entirely when it hits the over current limit.

i use 2 D131 BMSs in parallel to provide enuff current and that also doubles the balancing current. i was using 2 D131 on each pack but cut back to just one now on each pack and i can cause them to cut out when i mash the throttle and then it drops back down onto the 72V SLA pack until i let up on the throttle and the BMS turns back on.

 

[999zip999]

Dnmun do you have a set of sense wires for ez cell monitoring ?

 

[dnmun]

on my 24S lifepo4 pack i have two sets of sense wires, 12 pin plugs for a pair of ping 12S v2.5 BMSs that i can plug the cellogs into. nothing on the 21S lipo pack but it is not hard to keep balanced. i occasionally charge to 88.2V to force it to balance and it makes the balance boards of the 24S lifepo4 pack smoking hot because the two packs are connected in parallel. they get to about 3.67V/cell when the 21S lipo is at 88.2V DC and balancing at 4.2V/cell.

 

[mistercrash]

Dnmun, I looked at the D166 and I don't think I could live with 50A but if I get two and use them in parallel, llike you did on your car with the D131s, that would give me 100A and that would be sufficient. What do you think?

 

[dnmun]

i do that now. i did even more. on my 24S 87Ah lifepo4 pack i had to remove one of the 2 BMSs because i accidentally shorted it to the terminals of the pack.

but i cut it apart and made it into a slave. the power board of the D131 is separate from the balancing board underneath so i cut the pins along one side that connected them.

i also rewired it so i could use the charging mosfets in parallel with the output mosfets so now the slave power board has 20 mosfets in paralle instead of 15. plus there are 15 mosfets on the master power board so now a total of 35 mosfets. each cana handle about 10A so now i can push my lifepo4 pack to 350A but the inverter on my car will not allow that much draw.

 

[dnmun]

guess i did not answer your question.

yes, you can run the two in parallel and that doubles the balancing current too.

i have two of the D167 here for lifepo4 too that i bot in the last group buy if you are interested in them.

it would be interesting to see if i could wire up one of the D131 power boards i just worked on and use it as a slave to the D167 so the two could handle the load in parallel.