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High Power 10s Lipo Battery Pack with BMS


#625

A loop key is also more dependable.

Post a pic of your battery’s balance connector so I can see the wires attached to it.

I’ll make a diagram for you today after work


#626

Thanks so much man. I really would be screwed with your help.

Pic


#627

Note:
You can leave the balance ground wire on Battery 2 disconnected. It is not necessary to connect it anywhere.
Clip it short and make sure the end is insulated.
Another important point is to make sure you cut balance wires one at a time or else you will short the battery.


#628

@Gandinator
WARNING
Be very careful with this type of setup at least until the characteristics of this bms are known.
For example, braking on a full battery especially down hill.
Or durning hard acceleration.
The bms could shut off leaving you with a sudden loss of power and no brakes.


#629

Thanks so much.

I’ve seen on other videos that they connect Battery 1’s balance cable positive first (at the bottom of your diagram in this case) and they cut the positive wire on Battery 2.
However, I assume its different for every BMS right? I’ve seen my BMS’s diagram and see how it relates to yours.

If i do have a separate port for charging, I just connect the negative of the charge port to the C- right?

Lastly, If I were to have a monitor for the battery percentage where would I connect that.

Cheers man,


#630

I named the batteries 1 and 2 in relation to the sequence of cells 1-10.

It’s not really necessary to name them at all.
What is important is that the pack supplying the main black cable is cells 1-5
And the pack supplying the main red cable is cells 6-10
It is critical that the balance wires are connected in this sequence because if they are not correct, the bms will smoke.

There doesn’t appear to be a C- pad.
When there is no C- pad, the charge neg hos to P-

I will add a meter to the diagram when I get home from work.
It should go like this
Meter red between loop key and Vesc
Meter black between bms P- and Vesc
Then the meter will only be on when the loop key is connected


#631

Could you explain a bit more?
I don’t really understand why this is the case. On a simple 2S cell, how is it possible to balance each cell individually when the current flowing through both has to be the same?

Is this diagram correct:

I am designing my first esk8 and want to go with 10s. I was going for 2 x 5S cells. Except space, is there any disadvantage in doing so compared to 5 x 2S ?

Thanks!


#632

OK I found the answer in that video which is great:

However, I still don’t see why there can be an issue when you have 2 cells in parallel on the balance lead. They are in parallel so they have to be at the same voltage and will balance one another. Is this correct?


#633

In a perfect world, cells in parallel will automatically balance each other. The bms will see how ever many cells you have in parallel as one cell.
If the cells in parallel are not matched in terms of true capacity and internal resistance, then they will probably not charge and discharge evenly.

It is my opinion that a 1p battery is the best scenario for balancing.
This is one of the reasons that I prefer Lipos to Li-ions.


#634

I have added a battery meter to the diagram.


#635

Yes OK this makes sense if capacity and internal resistance are not a perfect match in the parallel branch. Thanks!


#636

Thanks so much man. You really helped me out a lot. Never thought people would take so much out of their time to help. Cheers. BIG UP NAMASAKI


#637

If you prefer 1P, how do you go about getting more range? Just bigger/more expensive batteries or individually balance charge each battery every couple discharges? I would like to put 4x 5000mah 6S LiPos into a 2S2P configuration for 12S 10Ah. Is BMS still usable? Thanks for all the help


#638

I’m ok with with medium range of 10-12 miles so a 10s 5ah battery works for me.
People who build for maximum range usually use Li-ion cells.

I believe it is better to use Li-ion cells for a multiple P battery because with Li-ion cells, all the the Parallel connections are made before the Series connections. This simplifies the balancing process because all cells in parallel automatically balance themselves and the bms will see each group as one cell.
And each P group will automatically and continuously balance itself even when the board is off.

With four 6s Lipos, the series connections are made before the parallel connections.
This rather complicates things.
You can parallel the low current balance wires.
But you can not parallel the high current connections between each and every cell.
There have been some who have done this but I’m not sure how well it worked out over time.

Gens Ace Tattu makes some high capacity Lipos that are very good but not cheap.

Or if you want some ridiculous range and power and don’t mind the heavy price:

@PatRocks uses the 22ah Tattu’s with amazing results.


#639

Thanks for the help @Namasaki