Which BMS does EM3ev use?

[Gorillazilla]

The mystery BMS used in these batteries?
https://em3ev.com/shop/52v-14s4p-shark/

If it's good enough for EM3ev then it's good enough for me.


I'm having a hard time pinning down a quality BMS that can handle a Cyclone 3KW at 48v, to fit this 91 cell case https://www.aliexpress.com/item/4001076311328.html?spm=a2g0o.order_list.0.0.21ef18029oozb5

One niggle is that apparently the EM3ev BMS cannot accept regen current?

Does anyone know which BMS EM3ev uses? Otherwise, any good suggestions?

 

[john61ct]

LLT Power, SHEN ZHEN LI LU TONG ELECTONIC TECHNOLOGY

https://www.lithiumbatterypcb.com/product-instructionev-battery-pcb-boardev-battery-pcb-board/ev-battery-pcb-board/smart-bms-of-power-battery

 

[Gorillazilla]

LLT Power, SHEN ZHEN LI LU TONG ELECTONIC TECHNOLOGY

https://www.lithiumbatterypcb.com/product-instructionev-battery-pcb-boardev-battery-pcb-board/ev-battery-pcb-board/smart-bms-of-power-battery

Cheers John, you're a star!

 

[john61ct]

Note their parent company is JBD

Jiabaida Technology
Dongguan Jiabaida Electronic Technology Co., Ltd

aka SZLLT

https://www.aliexpress.com/item/32794186005.html

CurrentConnected BMS
https://store.currentconnected.com/product/jbd

Overkill Solar BMS

are reco suppliers that may be better for support if needed

also Battery Hookup https://www.google.com/search?q=site:batteryhookup.com/products+bms


the generic "SMART" BMS sub-category is Xiaoxiang type, there are some FOSS customisable firmware out there

 

[Gorillazilla]

Note their parent company is JBD

Ahh so these are the same as from LLT power?

I'll be picking up one of these as it's the 13S version I need.
https://www.aliexpress.com/item/32876805034.html?spm=a2g0o.store_pc_groupList.8148356.12.41527cd7KGJnZE


Thanks again John, I'll let you know how I get on

(hopefully without the part!)

 

[john61ct]

I did not state they were the same, fact is I dunno

but why establish a whole separate subsidiary company and brand if they just sell the same models as the parent?

No one has ever provided evidence of which specific model Paul uses, or even if it the same over the years.

But in general these are well recommended by members I respect, check out the SMART BMS thread.

ANT is another one, but that is quite different

 

[Gorillazilla]

but why establish a whole separate subsidiary company and brand if they just sell the same models as the parent?

Does seem odd if that is the case, though they are almost the exact same price with free delivery for the 13S 60A units.
£34.33 from LLC and £34.84 from JBD on AliExpress

I do need two however, are they BOTH highly recommended? Because I could buy one from each and compare when they arrive for your curiosity.

I'll try and find that Smart BMS thread, I tried a quick search for "smart BMS" on the forum earlier and it was not on the first several pages of search results.

EDIT: I could not find that dang thread, trawled through the results all the way back to 2020... Could I get a link please?

 

[john61ct]

Maybe this?

https://endless-sphere.com/forums/viewtopic.php?f=14&t=88676&start=1650

Do not buy two different ones if you need them to be identical.

But otherwise would be interesting, who knows which is "better"?

Always good to have spares with cheap chinese stuff.

 

[john61ct]

https://www.google.com/search?q=site%3Aendless-sphere.com+smart-bms

https://www.google.com/search?q=site%3Aendless-sphere.com+Xiao-xiang

https://www.google.com/search?q=site%3Aendless-sphere.com+ANT+OR+JBD+OR+LLT

etc

 

[Gorillazilla]

Do not buy two different ones if you need them to be identical.

I don't need them to be identical, I won't be running the packs in parallel. Just carrying additional batteries out on longer rides and swapping them as needed. One for heading out, one for heading back home and the like.

I'll get one of each and get some comparisons up for you.


Thanks for the link, reading through that now.

 

[tomjasz]

D-Powercore

https://apps.apple.com/us/developer/d-powercore-co-ltd/id1459971734

http://www.d-powercore.com/class/19

 

[tomjasz]

LLT Power, SHEN ZHEN LI LU TONG ELECTONIC TECHNOLOGY

https://www.lithiumbatterypcb.com/product-instructionev-battery-pcb-boardev-battery-pcb-board/ev-battery-pcb-board/smart-bms-of-power-battery

NO! FFS!

 

[john61ct]

Sorry are you saying that EM3EV has used these?

Or that you reco them?

or...

 

[tomjasz]

I'm saying you are wrong. Paul uses D-Powercore. As pictured.

ALL of his batteries use D-Powercore. Where ever you got your information from is just incorrect.

 

[john61ct]

Interesting, then I stand corrected

 

[Gorillazilla]

I'm saying you are wrong. Paul uses D-Powercore. As pictured.

ALL of his batteries use D-Powercore. Where ever you got your information from is just incorrect.

The JBD/LLC BMS might actually be better for me than the one Paul uses, I asked LLC and JBD if their BMS can safely handle charging current from regen braking and they say it is safe to use regen braking with, which suits me as I want to put a small 250W direct drive on the front wheel to handle the area where the 3KW Cyclone is kind of inefficient, Cruising at 15MPH on flat road using a tiny 250W or less with pedal assistance.

Plus will save a little on chain wear, saving the chain for when it's actually needed for short to moderate stretches up extremely steep hills





Apparently the BMS Paul uses in EM3ev batteries are not safe to use regen braking with?

Mentioned here, search page for "regen": https://em3ev.com/shop/em3ev-52v-14s5p-jumbo-shark-ebike-battery/?doing_wp_cron=1647346904.7965528964996337890625

Wonder why that is? Anyone know?

I'd like to understand the principle. Does not make much sense to me as the output leads can handle the discharge current. current going the other way is no different, and I doubt there's a Diode involved to prevent reverse current flow....

Unless regen current from hard braking can be too high? Possibly frying BMS or burning the cell level fuses? (not directly related to the BMS but maybe that's what he means when he says regen current is not allowed?)

 

[kevinscargobike]

I think that's an optional battery parallel device that doesn't allow for regen:

"The battery parallel balancing device works from 10S (36V) to 14S (52V). As long as the voltages of the two batteries are the same – eg. both are 14S etc. it will work with all cell types and capacities. The device has a max discharge current of 60A and regen is not permitted. Please contact us if you are interested in this device."

 

[amberwolf]

And regen isn't permitted by it because it blocks the reverse flow of current (which is how it protects batteries with different SOCs in parallel). Not that it would be damaged, it just doesn't allow it to happen.


Regarding this:

I'd like to understand the principle. Does not make much sense to me as the output leads can handle the discharge current. current going the other way is no different, and I doubt there's a Diode involved to prevent reverse current flow....

Unless regen current from hard braking can be too high? Possibly frying BMS or burning the cell level fuses? (not directly related to the BMS but maybe that's what he means when he says regen current is not allowed?)

A BMS uses two sets of FETs. One is for charging, and the other for discharging. The charge FETs are typically only 1/4 or less the capability of the discharge FETs (sometimes using different FETs, sometimes using less of them, sometimes both). Regen currents can be MUCH higher than normal charging currents, which might be ok for a spike of a second or two under normal bicycle-type braking. But used for things like hill descents, etc., or frequent repeated braking in traffic, etc., or higher speed decelerations (more energy for longer periods) this can generate too much heat in teh charging FETs, and POOF.

POOF doesn't always mean BANG, either, in FETs it's often a silent failure in a shorted (stuck-on) mode. When it's stuck on, that means the BMS can no longer stop charging if there is a problem, and it becomes possible to overcharge cells and damage them, with all the possible failure modes that creates.

 

[torker]

This has me wondering. I run two of EM3EV batteries. 48v on my fsr. I use regenerative rear brake. The only rear brake I have. I don't have a lot of cycles or miles on it. No problems yet. Is it is a threat to my battery?

 

[tomjasz]

This has me wondering. I run two of EM3EV batteries. 48v on my fsr. I use regenerative rear brake. The only rear brake I have. I don't have a lot of cycles or miles on it. No problems yet. Is it is a threat to my battery?

I think it’s being misread.

“ The battery parallel balancing device works from 10S (36V) to 14S (52V). As long as the voltages of the two batteries are the same – eg. both are 14S etc. it will work with all cell types and capacities. The device has a max discharge current of 60A and regen is not permitted. Please contact us if you are interested in this device.

 

[Gorillazilla]

This has me wondering. I run two of EM3EV batteries. 48v on my fsr. I use regenerative rear brake. The only rear brake I have. I don't have a lot of cycles or miles on it. No problems yet. Is it is a threat to my battery?

I think it’s being misread.

“ The battery parallel balancing device works from 10S (36V) to 14S (52V). As long as the voltages of the two batteries are the same – eg. both are 14S etc. it will work with all cell types and capacities. The device has a max discharge current of 60A and regen is not permitted. Please contact us if you are interested in this device.

Thanks for that, it's just the way they abruptly cut into talking about an optional battery parallel saftey device right in the BMS description, mystery solved

 

[Gorillazilla]

Maybe this?

https://endless-sphere.com/forums/viewtopic.php?f=14&t=88676&start=1650

Do not buy two different ones if you need them to be identical.

But otherwise would be interesting, who knows which is "better"?

Always good to have spares with cheap chinese stuff.

Just I'd seed a bit of info back to the forum rather than just leech, so here's update for you John, turns out the BMS from the "two" different companies are pretty much identical despite one being from JBD and the other from LLC



Arrived packed identically

And look identical as far as I can tell.

And have the same product code

Only difference I could see was a slight difference in the code on the bluetooth module

 

[Gorillazilla]

SMART BMS thread.

Is there a guide on how to wire em up in that thread?
As I could use a little help with that as they came without instructions...

 

[john61ct]

Great data point thanks.

LLT Power is a JBD subsidiary

SMART BMS thread.

Is there a guide on how to wire em up in that thread?
As I could use a little help with that as they came without instructions...

I'm sure, but it's a long slog.

Maybe just get all your notes together take clear pics of everything, and tack on your questions.

Assuming you've already asked your seller for docs datasheet diagrams etc, tried Googling etc

 

[john61ct]

Actually that thread so big and old, maybe best to start a new one, put the make/model in the title for future google fu.