JBD / Overkill BMS 120A 4S Lifepo4 in series / parallel

[GSXR1000]

Have you tried it (or anyone else on here)? I can't think of a reason it wouldn't work, I just find it odd overkill would say its not recommended. Other battery manufacturers (battle born) also don't seem to like putting their systems into series

the reason you could do 2 in series like in a RV. you can not put them all in on box due to space available

 

[GSXR1000]

What I see in the picture is 8s. The top drawing is also 8s. The bottom drawing would be 2p4s

yes I see it... but I was using 2 bms in the top picture to make 12v x 2

 

[HRTKD]

Have you tried it (or anyone else on here)? I can't think of a reason it wouldn't work, I just find it odd overkill would say its not recommended. Other battery manufacturers (battle born) also don't seem to like putting their systems into series

Battery A and battery B are connected in parallel. During charging battery A hits High Voltage Disconnect. What happens to battery B? It also stops getting charged.

 

[HRTKD]

yes I see it... but I was using 2 bms in the top picture to make 12v x 2

Ah, but only once BMS was actually connected.

 

[GSXR1000]

Battery A and battery B are connected in parallel. During charging battery A hits High Voltage Disconnect. What happens to battery B? It also stops getting charged.

be the same thing as 1 cell in 8s going over volt would stop the charge on all 8

 

[GSXR1000]

Ah, but only once BMS was actually connected.

 

[HRTKD]

View attachment 39605

Wires from the BMS on the left go nowhere. Bus bars are setup for an 8s 24v battery.

 

[HRTKD]

be the same thing as 1 cell in 8s going over volt would stop the charge on all 8

Yes, that's the usual counter argument.

In the case of the 8s there may be cell balancing that takes place while charging of all cells is still allowed. When two batteries are in series, high voltage disconnect for either the battery or a cell cuts off charge to both batteries. For the most part, it's a wash. But if I wanted a 24v battery, I would not be messing around with two 12v BMS in series. Even though I already have the cells and BMS to switch from 12v 4s2p to 24v with those same two batteries in series, I would not. I would purchase a new 8s BMS.

 

[GSXR1000]

Wires from the BMS on the left go nowhere. Bus bars are setup for an 8s 24v battery.

no look at the center cells not series.. I drew in the blue wires on the left.. so the outside are the 2 negative and center positive.. I decided not to go this way..

 

[HRTKD]

What's the amp rating of a drawn line???

OK, I'll accept your doctored photo and call it 4s2p. As long as it works, that's what matters.

 

[Zwy]

Has anyone tried to parallel (2) BMS on the same battery ( example one 4S1P battery) --curious if this would work

You will be limited to the amperage rating of one BMS. Let's say you build a 24v battery with 4S2P packs using the Overkill 120a 4S BMs on each pack. You will only have a max amperage of 120a.

 

[squowse]

You will be limited to the amperage rating of one BMS. Let's say you build a 24v battery with 4S2P packs using the Overkill 120a 4S BMs on each pack. You will only have a max amperage of 120a.

He's suggesting putting the 2 bms in parallel. So the current capacity would be doubled.

 

[GSXR1000]

Wires from the BMS on the left go nowhere. Bus bars are setup for an 8s 24v battery.

this is my final configuration p

 

[HRTKD]

2p4s! Looks like a nice, tight fit in that box and even includes a compression frame. Looks great!

 

[GSXR1000]

2p4s! Looks like a nice, tight fit in that box and even includes a compression frame. Looks great!

$34 battery box... and perfect size for the location I want it in the RV

 

[Pappion]

nice battery box, link?

 

[squowse]

$34 battery box... and perfect size for the location I want it in the RV

You might want to start your own thread

 

[GSXR1000]

nice battery box, link?

Just ordered Lifepo4 prismatic cell 3.2V 280Ah lithium lifepo4

That is great! I am going to order another set from BASEN after CN new year is over. Right now the price has gone up a little bit, not sure if it will fall in the futire or not.

diysolarforum.com

You might want to start your own thread

 

[Zwy]

He's suggesting putting the 2 bms in parallel. So the current capacity would be doubled.

Who is he? You asked the original question and asked again here about series.

The latter - 1 BMS per 4 cells.
I was asking for series or parallel. Or even both.

I answered the series question that you asked. Just because responses are listed in a certain order does not mean the next post is about the previous post.

 

[squowse]

Who is he? You asked the original question and asked again here about series.


I answered the series question that you asked. Just because responses are listed in a certain order does not mean the next post is about the previous post.

You quoted Chops728. That is "he".