Recommendation for a BMS

[warkittens26]

Hi All,

I have a battery that I made that is 9P10S Lithium Ion 18650 Batteries. I was all set to solder on my BMS, but then someone I know mentioned that what I got is not a true BMS. He did not elaborate in his email as why it's not a "true" BMS and he now out of country for a month with access to email. Grrrrr

Battery Details:
36Volts/19.8Ah
9 Parallel/10 Series

Current BMS that I own:
44V 48V 50.4V 12S 45A Lithium ion, Li-ion LiPo, Li-Polymer, Battery BMS PCB System (See attached picture)
I had originally bought it cause I was building a 48V 8P/12S battery, but have since changed it to a 9P/10S that will work with my existing controller.

Anyway, looking for a recommendation for a "true" BMS unit. And if anyone knows why this BMS is not a good choice, I would like to know why. Any suggestion would be greatly appreciated.

 

[greg_p]

I just know that there are resistive BMS, that bleed cells that are over the max voltage, once whole battery voltage goes over a given voltage. And there are capacitive ones, that just pump up the energy from over-charged cells, and probably distribute to lower charged ones. But all seems to works, it's just probably some are working more than the other.

 

[gloots]

Despite days of reading, I still can't make a shortlist of what BMS to buy (I plan on making my own battery pack too). I looked at the one you attached here as a picture too (lots of similar ones on ebay).

 

[wesnewell]

Just a wag, but he was probably referring to the fact that you are building a 10s battery pack and your bms is for a 12s battery pack.

 

[greg_p]

A 10s battery must have a 10s bms in the appropriate chemistry...

 

[warkittens26]

Was thinking of buying this one on ebay, see link below. Would this work for my 10 series 9 parallel (36v/19.8Ah)?

http://www.ebay.com/itm/Battery-Protection-BMS-PCB-Board-for-10-Packs-36V-Li-ion-Cell-max-40A-w-Balance-/271803920379?hash=item3f48c6affb:g:ZKwAAOSwBLlVAcCf

Take care,

Michael

 

[Alan2000]

I'm also looking for a 36v BMS. Seems like there must a FAQ on BMS and list of recommended units out there. I saw the same one on eBay and was wondering if it is a good one to use.

 

[Lurkin]

This is precisely why I was trying to get a thread going re best ways to test a BMS, which has had no response. Reality is, if you don't know what the first person was on about, how can you write it off as a poor BMS? I'll update it as I come across more information: https://endless-sphere.com/forums/viewtopic.php?f=14&t=79092

 

[warkittens26]

Well I bought the one off ebay. Ill report back on how it does.

 

[Alan2000]

Well I bought the one off ebay. Ill report back on how it does.

Ditto here.

 

[titusmc]

The BMS you show in the picture is a SuPower Battery BMS. I have used a 13S one for about a year and it seems to perform well and do a top-end balancing. I've never monitored the cells when this occurs, so I can't verify what balancing method it employs, but my charger stops and starts over several hours, leading me to believe it is a simple resistive bleed of high groups.

My current builds are all 14S and, up until recently, SuPower did not have any 14S BMS boards, so I contacted them and asked about it and they told me to use a 16S with the last 2 balancing wires unconnected. I haven't done this yet, so I'm not sure if it really works (my fear is I would lose the active balancing since the board will think the voltage is lower), but you may be able to use a 12S board with 10S battery in the same way.

 

[llile]

Well I am in the same boat as you guys, just fried an 80A 24S BMS and looking to replace it.

Adaptto http://adaptto.com/Products/BMS/ makes a BMS that some people have mentioned here, but if I understand correctly it only works with their motor controllers. I already have an existing motor controller and Cycle Analyst that I want to keep. That one is probably out.

BMS Battery seems to be mentioned a lot around here https://bmsbattery.com/ebike-battery/378-24s-lifepo4-bms-battery-management-system-battery.html It's a hundred bucks-ish, has short circuit protection ( a plus). This one looks like a contender.

Batteryspace seems to make something but I haven't made heads or tails of it yet. http://www.batteryspace.com/advancedbmsbatterymanagementsystemfor1-24cellslifepo4pack.aspx lots of parts and pieces, not well described. I am left confused as to what parts I would need to put together. There are some folks on this board griping about batteryspace, can't tell if that is one disgruntled guy or a number of them. Maybe they are a fantastic company for all I know.

Here is Supower's entry http://www.batterysupports.com/72v-...battery-bms-lfp-pcb-pcm-smt-system-p-291.html I like their specs a little better than BMS battery - These guys balance for 3.5V vs. 3.6V for BMS battery. If I understand correctly (and I do not) this may extend the life of the battery a little. Same with the low end, supower disconnects at 2.1V vs 2.0V for the BMSBattery unit. $72 for this one. Another contender.

There are about 500 different BMS on Ebay and AliExpress. Who knows who made them?

A minute ago I was looking at a really advanced $300-sh BMS with a keyswitch input, an LCD battery gas gauge, 4 temperature inputs, and a smartphone interface, made by some guy in the Soviet bloc but for the life of me I can't find it again.

Here is a compilation (perhaps dated?) of specs for several BMS's. This is a gold mine of info http://liionbms.com/php/bms_options.php

Which of these have people used with good luck?

 

[warkittens26]

The BMS you show in the picture is a SuPower Battery BMS. I have used a 13S one for about a year and it seems to perform well and do a top-end balancing. I've never monitored the cells when this occurs, so I can't verify what balancing method it employs, but my charger stops and starts over several hours, leading me to believe it is a simple resistive bleed of high groups.

My current builds are all 14S and, up until recently, SuPower did not have any 14S BMS boards, so I contacted them and asked about it and they told me to use a 16S with the last 2 balancing wires unconnected. I haven't done this yet, so I'm not sure if it really works (my fear is I would lose the active balancing since the board will think the voltage is lower), but you may be able to use a 12S board with 10S battery in the same way.

Well I have had zero success with the BMS I bought off eBay. No matter what I do I cant get any current off my discharge/charge ports. I was thinking I would try my 12s Supower BMS and leave the last wire disconnected. I'm not sure how the BMS would treat this....seems like it would shut off as it would see the last two banks as an LVC situation. But my 12s is just collecting dust anyways, so its worth a try. Ill let ya know this worked.

 

[llile]

Here is a guy who recommends Supower over Besttechpower, whom I've never heard of.

So I say screw Bestechpower and ‘just deal with Supower from now on.

 

[Ykick]

Here is a guy who recommends Supower over Besttechpower, whom I've never heard of.

So I say screw Bestechpower and ‘just deal with Supower from now on.

I resemble that “guy”, haha…

I’m still PO’d about most Bestechpower BMS I’ve had the misfortune of buying. I don’t like bagging on EV companies and some people might not experience the problems I did but you should know what you’re getting into when dealing with that company.

My point is that using eBay as the middleman for Supower BMS, you don’t have to buy 2qty or be dinged for PP fees. Plus, if the damn thing arrives DOA (which appears to be fairly common) there’s some recourse for return/refund via eBay/PP.

 

[friendly1uk]

48v 12s ? I can see your mates complaint. I guess that pic is generic and you specified what you really wanted.

The bestec boards have a lot of tech support here and will let you skip cells. I got mine through the post and put it on the shelf unimpressed though.

12s will probably work with your controller. Most 36v kit will. It's about the upper limit though and I'm aware the s06s won't like it. 12s is 44v which peaks at 50.4v hot off the charger. What is your controller?

 

[Alan2000]

My BMS from Hong Kong arrived. Ordered 3/28 and arrived 4/9. Paid $2 more to order from a guy with good feedback. Still only $16 delivered. Hoping my custom battery pack arrives this week to give it a try. Hopefully the "high quality" portion of description is accurate.

 

[warkittens26]

I hooked up my 12S SuPower BMS yesterday. Soldered on 10 wires (obviously didnt use the last 2, just cut them a bit short and taped the ends of with electrical tape) and plugged it into the socket. Getting 41volts even with a load...Finally. Hooked the battery up to my ebike controller and did 36 miles with out issue. Thus far I have not been able to charge anything using a BMS, turns out it was the charger socket I was using. When I plugged in my charger, the output through my charger socket was zero...I really should have checked this first.

My concern was in charging the battery as I had a 12S BMS on a 10S battery. I wondered how the BMS would treat B11 and B12 pins as there is no bank connected. Well so far I went from 37.22Volts up to 41.87Volts when my charger shut off.
B1=4.22V
B2=4.11V
B3=4.12V
B4=4.22V
B5=4.24V
B6=4.23V
B7=4.23V
B8=4.23V
B9=4.24V
B10=4.10V

So far its done a reasonable job of charging the cells up to 4.2V, My guess is that B9 trigged the Over Voltage Cutoff and the BMS shut down. I'm hoping for the cells to start balancing out. Gonna leave it on the charger for a couple days to let things balance out. From what I have experimented with, I have not seen any issues using a 12S BMS on a 10S Battery in discharging or charging. Though I am ordering the SuPower 10S BMS as I would prefer to have the correct BMS for my battery.

I have tried to use the BMS pictured in Alan2000's post, however, I have had no success with it at all. Prefer the the SuPower BMS, but that's just me.

Take care,

Michael

 

[llile]

OK, where do we get all the fiddly stuff that finishes a battery/BMS?

There are very few sources of large diameter heat shrink, and none I could find in the US. Some of the battery sites https://bmsbattery.com/shrink-tube/...ig-shrink-tube.html#/418-half_perimetermm-300 sell heat shrink up to 350mm across the flat (this would be 2X350mm circumference or 222mm diameter. For some reason this is called "Flat Diameter" by some sellers, which makes no sense since things with diameters are not flat.)

If your battery is bigger than that, you have two alternatives: This Ebay seller stocks nothing but heat shrink, woven tubing and silicon tubing up to 500mm flat width http://stores.ebay.com/jacktube/?_dmd=2&_nkw=50mm He's in Hong Kong.

AliExpress is increasingly a good alternative to Ebay for stuff sourced in china - often you are dealing direct with manufacturers. Here's an Aliexpress store with 300mm heat shrink: http://www.aliexpress.com/store/pro...fcd5a07efc76722-1461074402763-08397-mYfYvfaU3


OK, how about Kaptan Tape? You can buy this in the US from big electronics wholesalers like Mouser, but at ten prices. Once again you'll be delaing with Aliexpress or ebay. Here is a guy on Ebay located in teh US that stocks Kaptan tape cheap. http://www.ebay.com/itm/151863884483?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT Why do yuo want Kaptan tape? absolute best insulation, thin, watertight, high temperature. Kaptan is a great choice to cover the heat sink on your BMS if it is a flat aluminum sheet - still transfers heat, no electrical shorting risk.

Anderson connectors can be found at Ebikes.ca (Whew! an Ebike Supplier) or Mouser.com http://www.mouser.com/Search/Refine.aspx?Keyword=anderson+15/45

Another nice-to-have is EVA foam for spacers, say to fill up between the BMS and the battery edges. EVA foam is nonconducting, waterproof, easy to cut. Hot glue is actually a form of EVA. ou can find this on Aliexpress again http://www.aliexpress.com/item/5pcs...fcd5a07efc76722-1461073359205-03531-VVFMvnUVv But why bother? The "craft foam" they sell at Jo-Anne'es and Michaels is actually EVA foam, says so right on the tag. This cheap kids toy is actually a high quality electrical insulation, used on the back of solar panels for example.

 

[Alan2000]

.......
I have tried to use the BMS pictured in Alan2000's post, however, I have had no success with it at all. Prefer the the SuPower BMS, but that's just me.

Take care,

Michael

What problems did you have with that BMS? I'm pretty sure I'm going to run mine without a BMS at least for a while. The 18650 cells stay pretty well balanced. My LiPo balance charger will not over charge the pack. The controller on the bike will not allow the pack to over drain. So I'm thinking a BMS may be more of a liability than a benefit to me.

 

[cycborg]

I have tried to use the BMS pictured in Alan2000's post, however, I have had no success with it at all.

I've been using these with no problems - what trouble did you have with it?

I haven't done exhaustive testing on them, but charging, discharging, and LVC all work fine. LVC for me happens at 29 V, so 2.9 V/cell rather than the 2.5 V in the specs, but maybe that's due to a weak cell somewhere.