Is it OK to wire only 10 cells to a 14 cell BMS?

[RootedSuperuser]

Basically the subject header says it all ... Can I wire in only 10 cells to a 14 cell BMS by omitting the 1st 4 leads?
Will this configuration work properly to balance the pack to a max 42 volts?

 

[dogman dan]

no, but you could have it balance just ten of the cells, 1-10, or 5-14.

Pointless. Rig a pair of balance plugs so you can check your cells with a cellog, and or use other devices that balance the pack up to 8 cells at a time.

 

[RootedSuperuser]

no, but you could have it balance just ten of the cells, 1-10, or 5-14.

1st You say 'NO'
Then you say you can balance a using 1-10 or 5-14.
So WTF is it?! Yes you can, or NO you can't do this...
Pffffttt......Smokin again?

 

[Chalo]

Cell charge balancing isn't the only thing BMS does.

If you don't have enough total voltage (in this case, not enough cells) or enough per-cell voltage (because some are 0V), the BMS will disconnect the load.

 

[teklektik]

Basically the subject header says it all ... Can I wire in only 10 cells to a 14 cell BMS by omitting the 1st 4 leads?

It really depends on the BMS.

We used to have a member 'dnum' who was a big fan of the BesttechPower D167 which is well documented to operate at lower cell counts that the BMS maximum series capacity.

Here's a reference that mentions leaving the upper (not lower) balance leads disconnected which makes perfect sense because of the Gnd reference:
https://endless-sphere.com/forums/viewtopic.php?f=3&t=46646&start=25#p918967

Here's dnum's recommendation for using the D167 for any series up to 20S. He has a post or two about his experiments in this vein, but I can't find them on a quick search...
https://endless-sphere.com/forums/viewtopic.php?f=14&t=67288#p1013101

So - this could quite possibly work for your particular BMS. If you have no BMS in hand, you might spring for a couple D167's (minimum order quantity).

 

[tomeckm]

I can only confirm that bms 14s from Greentime (Aliexpress) works well on 10s config. Cells connected starting from 1 one. Balancing and low voltage cut-off both works seamlesly.

 

[dogman dan]

NO, it won't balance 14 cells in the pack, which it seemed like you were asking. " will it balance the pack to 42v ?"

Yes, it will balance any10 cells in sequence, like 1-10, 2-11, and so on, to 42 v. but what the hell good does that do you? You still have 4 cells you have to be a human bms for. 4 cells, 14 cells naked, I don't see much benefit from the bms myself.

If you know for sure one cell is trash, then I suppose you could at least put the lvc protection of the bms on the section of the pack that has that cell in it.

I'd dump that shitty cell myself.

 

[fechter]

It does depend on the BMS design. If you post a good picture of it, I might be able to tell from the picture.

Most of the older style chinese BMS unit can work with lower cell counts. You need to attach your cells starting at B1 and have all the unused wires on the positive end and tie them all together. I have a 15s BMS working on a 8s pack and it all functions properly.

The way the circuit is designed, the first 3 cells at the negative end of the pack operate the control circuit, so you need a minimum of 3s and the unused channels have to be at the positive end.

More modern designs use a chip that can monitor multiple cells and will trigger a fault condition if cells are not connected. Many of these are programmable for fewer cells, but it is dependent on the exact chips used.

 

[Sunder]

I think Fetcher's signature answers the question better than his post... Test it. what's the worst that could happen? With 4 less cells, there is no chance of over voltage damage.

But just in case you are going the 1000 opinions route, BMS Battery's ones allegedly can. I ordered 3 x 12S BMS and they sent me 3 x 16S. When I said they sent me the wrong ones, they claimed I just have to desolder the 12S JST females on the battery side, and solder their 16S connector, less the last 4 wires. I declined that as a reasonable action so they could avoid sending me the correct parts. Paypal agreed.

 

[RootedSuperuser]

I can only confirm that bms 14s from Greentime (Aliexpress) works well on 10s config. Cells connected starting from 1 one. Balancing and low voltage cut-off both works seamlesly.

I wasn't sure if you have to omit the unneeded connections from the top or bottom configuration.
batterysupports.com confirmed this setup, START FROM THE BOTTOM, OMIT FROM THE TOP.
FORGET ABOUT THE 36, 48 OR 52 VOLT DESIGNATION!
If you buy a 20 cell BMS its good fro 1 to 20 cells!
So for me it's a 16 cell BMS with the Bluetooth Module for a 14 cell pack.

+1 FOR tomeckm

FYI .... evfittinggreentime @ aliex sent me a BMS with the wrong count Balance Connector on a rush order.
He wouldn't express the correct connector out to me or issue a small bank credit, I had to purchase the connector from DigiKey USA for the extra price of 25 bucks!

 

[999zip999]

Going Chinese cheap isn't always cheap.

 

[fechter]

batterysupports.com confirmed this setup, START FROM THE BOTTOM, OMIT FROM THE TOP.
FORGET ABOUT THE 36, 48 OR 52 VOLT DESIGNATION!
If you buy a 20 cell BMS its good fro 1 to 20 cells!
So for me it's a 16 cell BMS with the Bluetooth Module for a 14 cell pack.

Most of the cheap ones need a minimum of 3 cells to work. The ones with Bluetooth might need a different setup for fewer cells.