Opinions on this BMS

BobinTN

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Feb 23, 2017
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32
Hello;
I am interested in opinions on using this for my 7s80p battery BMS.

https://www.electriccarpartscompany.com/BALANCERS-EQUALIZERS


I am struggling with Stuart Pittaways system (old eyes and not good skills trying to build the boards {I am having about a 50% success rate on boards running correctly and keeping the controller up and running.

I am not opposed to using Batrium, just have not gone their yet.

Bob
 

daromer

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Above is ONLY balancers without ANY feedback. So you still need to complement a BMS to it and a feedback so you know whats going on. personally i would not recommend it at all because people dont know if they are balancing or not. Yes people state the battery are in balance and therefore its working... But how do you know?

Lets say you drive 150km/h on the road.. Just because the police havent pulled you over doesnt make the speed legal :p

Buying above when planning to buy batrium or other is just to throw money in the lake because above is dead darn expensive to what they actually do. The balance current is rather low at voltage ranges diff like 100mV. They only balance at full current when voltage diff is like 2V....
 

BobinTN

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Feb 23, 2017
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Thanks for the responses guys.

I have 2 devices that alarm when the packs get to far out of balance. That is what I was using before and they seemed to serve my purpose rather well.
My 18650 packs aren't the best (previous sentence), I thought the balance current and specs (50mV) sounded pretty good for keeping the packs stabilized.

Their may be a Batrium in my future.
 

Satiriasis

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Dec 25, 2018
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BobinTN said:
Hello;
I am interested in opinions on using this for my 7s80p battery BMS.

https://www.electriccarpartscompany.com/BALANCERS-EQUALIZERS

Hi Bob,

your BMS looks interesting, I am also in the middle of consideration what kind of BMS I am going to use. I don't like that most of those cheap BMSuse resistors to balance the pack where the extra energy goes to heat... I like the idea of using supercapacitors for balancing, but havent seen anyone using it,something likethis one.
 

daromer

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Satirasis: The link in beginning is not a bms. Its just a balancer...

Your link is a better BMS. Note that when you need to balance that much energy compare to wasted into heat using passive... you have serious problem with your battery bank from the start.

The cost going active is so much more so that the money saved is rather litle and it takes years before you can make that up. I use passive only on my 100kWh battery bank and I hardly balance anything.
 

Korishan

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Yes, if balancing more than a few 100mA is required on a continual basis, there's something wrong with that pack. Find the leaker and replace it. Otherwise, you're basically burning money and tossing it into the wind.
 

Satiriasis

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Dec 25, 2018
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Yeah, I thought that just carefully compute to have each parallel group the same capacity should be enough. Do you please have some more info for those passive balancers that you are using? Thanks
 

Korishan

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The passive ones that Daromer is using, as many others, is the Batrium BMS. It comes with passive balancing boards.
 

jonyjoe505

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Feb 28, 2018
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The active balancers on your link work great on a battery that won't stay in balance. I been using it on my 220 ah lifepo4 pack. Without out those balancers 1 cell always charges faster then the other 3, I been using them almost a year and pack has been in perfect balance. When I built my pack with 160 x 5.5 ah 32650 cells, I never tested each cell for capacity and suspect that is where my problem. Its too much hassle to take the pack apart to test every celland so farthe active balancers have been doing a good job for me. The cost on these were 92 dollars when I bought it for a 4s model, price has gone up since then.

image_ofqhzh.jpg


Recently I saw other active balancers on ebay but there no reviews on how well they work, a 4s model cost 39 dollar and is suppose to balance at 3 amps this is the name of it on ebay(12V 3 to 4 Series 3.7V LiCoMn Lithium battery Active Balance board BMS Inductor)
FEATURES
5-50mV deployment of unbalanced pressure difference between two arbitrary cores
Can be configured to charge, discharge, start equalization at rest
High Frequency current Peak of active Equalization inductor up to 3A
Active equalization frequency up to 200KHz
Jiantao, 94 V-0 level KB high fire prevention level double glass fiber board
Active Equalization to support Unbalance of Multicompound Lithium Battery
Maximum cascade stacking to 16-string active equalization
Very low power consumption, SHIP mode power consumption 85uAn Standby mode power consumption 400uA
Standard I2C communication interface support, accord with SMbus communication protocol
Each equalization channel has a corresponding temperature probe


image_kojwlm.jpg


And I saw these on batteryblocs website, they have a video on there use in youtube. They bleed the cell at more then 1 amp and one thing that it does is it has an alarm that will sound if the voltage goes too high or too low. These are 13.50 each. Its better then the bms built-in ones that balance at less then 65ma.

image_ldbfra.jpg
 

LEDSchlucker

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Dec 20, 2018
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I am on building an overkill active balancer for my powerwall, When the project gets more than just planning, I'll start a thread about it. It will have a max of around 5A continuous balancing current.
 

HollandNL

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Nov 16, 2018
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emuland-metroman said:
lifepo4 bms (top passive balancing) 1.6A max
https://www.ev-power.eu/Battery-Management/Cell-Balancing-Module-3-60V-1-7A.html

i'm going to buy it. and test (no test found online)

These work very well, they turn on a little bit high for my liking , but well within battery manufacturers specs
I actually use them in conjunction with a 'normal' bms.

if you have 8s or higher, these work -very- well, starting to bleed a little bit at 3,47V and go full bleed (1A IIRC) at about 3,55V for 16s packs you can't beat the price... Ow and they have LED's ;)
you'll also have to combine these with a bms.

https://www.aliexpress.com/item/3S-...nt-Active-Equalizer/32960521146.html?spm=2114
 

emuland-metroman

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i have bought that 2 month ago.

tested yesterday, but seems start to bleed too late.

Fast charge 10A and 1 cell hit 3.7v.

need to check with more time.

there's a xst splitter? (1 from battery then more to bms/balancer etc)
 

HollandNL

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emuland-metroman said:
i have bought that 2 month ago.

tested yesterday, but seems start to bleed too late.

Fast charge 10A and 1 cell hit 3.7v.

need to check with more time.

there's a xst splitter? (1 from battery then more to bms/balancer etc)

are you sure you have the correct version? (LiFePO4 - 3.2V)
 

Cherry67

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May 13, 2018
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LEDSchlucker said:
I am on building an overkill active balancer for my powerwall, When the project gets more than just planning, I'll start a thread about it. It will have a max of around 5A continuous balancing current.

With every respect, what is the reason to hav e such a powerful balancer ?
 

LEDSchlucker

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Dec 20, 2018
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There's no real reason for the high current yet, it's just the fun of building it, and the mosfets I'll use can handle the current...
 

Mikethezipper

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Jul 7, 2018
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LEDSchlucker said:
There's no real reason for the high current yet, it's just the fun of building it, and the mosfets I'll use can handle the current...

The limiting thing here isn't really the current, you can easily have mosfets that'll do way more than that. At some point you run into an issue with heat.
I've got a balancing board in the public domain that does 4A - the mosfets can do over 10A, but the limiting factor is the JST-XH connectors that really shouldn't be pushed too hard. Since it's on EasyEDA - you could easily clone what I have, and make some changes to have it suit your purposes. Change out the connectors for something higher duty, and route the gates from the mosfets to the nano that's onboard and you can have a ready to go board. The board already has a ton of temp sensors to monitor temps of the mosfets, the board, and the balance resistors. Also, it has a buck on board with a 4-wire connector for a fan - so you can have active cooling kick on when that sucker turns into a toaster.
 

Cherry67

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May 13, 2018
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emuland-metroman said:
i have bought that 2 month ago.

tested yesterday, but seems start to bleed too late.

Fast charge 10A and 1 cell hit 3.7v.

need to check with more time.

there's a xst splitter? (1 from battery then more to bms/balancer etc)

You are using these Balancers out of their intended use, or out of his possibilities.
The balancing current is for balancing, not for surging unlimited Load current when the cell is full.

The high current must be reduced by another of the BMS functions or in the charger circuit, or another overload prorection should hit.
 
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