5s being charged when in series with a 6s under discharge?!?

[adrock8519]

Hi,

I have been running 6s,6s,5s,5s 5000mah in series and then pallaling this to another string of 6s,6s,5s,5s of 5000mah to make 22s2p. This set up seems to work well and I only have to balance charge when I run it lower than 3.7v.

However when I use my 4 spare batteries just o quickly pop out (6s in series with 5s and then another 6s in series with 5s the both parralled. 11s2p Ive notice the 5s battery cell voltages going over 4.4 v whilst he cells in the 6s packs dropping as normal after about a 1.5ah ride?!?!

Ive attached some pictures of how I wired this up. I know usually you would parallel connection then go in series but I did it this way to save having to use more wire and connectors...

 

[dnmun]

when two batteries are connected in parallel, the battery with the higher voltage will push charge into the battery with lower voltage. you have one pack that is already fully charged in that battery so when more charge piles in it forces the cell voltages to high levels. at least it did not ignite. but keep trying.

 

[dogman dan]

I can't see what is what on the wires. But it sure does sound like you must have some how paralleled 6s with 5s.

 

[leffex]

Hi,

I have been running 6s,6s,5s,5s 5000mah in series and then pallaling this to another string of 6s,6s,5s,5s of 5000mah to make 22s2p. This set up seems to work well and I only have to balance charge when I run it lower than 3.7v.

However when I use my 4 spare batteries just o quickly pop out (6s in series with 5s and then another 6s in series with 5s the both parralled. 11s2p Ive notice the 5s battery cell voltages going over 4.4 v whilst he cells in the 6s packs dropping as normal after about a 1.5ah ride?!?!

Ive attached some pictures of how I wired this up. I know usually you would parallel connection then go in series but I did it this way to save having to use more wire and connectors...

4.4V is bad its dangerous and not specified for the batteries. Max is 4.2V. but some voltage readers read lower or little higher.

You can connect in series or parallel first but when you parallel you must do it with the same battery size 6S, together with 6s. and the 5S must parallel with only 5s. I think you make one error paralling 5s and 6s that makes voltage flow from the higher battery equalizing to the lesser battery and overcharge it. that s why you saw 4.4v per cell.

you got the hang of it, its good you check cell before and after charge.

 

[adrock8519]

Yeah I understand a high voltage pack will discharge to the lower volt pack in parallel, but surely when I put the 6s in series with the 5's this make and 11s and then parallel to another 11s ..?

 

[dogman dan]

Exactly, but the question is,,,, Did you actually do that, or did you actually parallel 6s with 5 s somehow.

I can't tell from the pictures. But it seems that something higher voltage must have been paralleled with the 5s.

Or, if you find out how you did pluck free recharge from thin air, LET US IN on how you did it. 8) It's just so easy to misconnect that bowl of spaghetti. Some how you connected a higher voltage to your 5s.

But hey, you didn't KFF and melt off a fingernail.

 

[dnmun]

like i said, the pack which overcharged started out as a fully charged pack in series with another pack to make the 11S. it was lower in voltage than the other 11S he put it in parallel with.

when charge went from the higher voltage to the lower voltage then the pack that had been fully charged was overcharged to 4.4V.

i suspect this may happen often.

 

[teslanv]

dnmun has a good thought there...

It is a subtle thing, where if you are not careful and connect a fully charged 5S and a partially charged 6S in series at say (4.2Vx5 + 3.8Vx6=43.8V) and then parallel that with another of the same configuration, except both 6S & 5S packs are fully charged (4.2x5 + 4.2x6=46.2V) then each 11S half will equalize to a common voltage of 45V, but then that means that the first 11S pack that started out at 43.8V has now overcharged the 5S pack by a couple tenths of a volt per cell. And of course, further charging will only exacerbate the problem.

Here is my suggestion:

take the packs apart and balance each pack (5S or 6S) one at a time to a common voltage. Storage Voltage would be best or about 3.85V per cell.

Then take the 6S Packs and parallel them together.
And Take the 5S packs and parallel them together.
Then Series connect the two larger packs.

Always parallel BEFORE Series, is how I like to do it.

 

[adrock8519]

Exactly, but the question is,,,, Did you actually do that, or did you actually parallel 6s with 5 s somehow.

I can't tell from the pictures. But it seems that something higher voltage must have been paralleled with the 5s.

Or, if you find out how you did pluck free recharge from thin air, LET US IN on how you did it. 8) It's just so easy to misconnect that bowl of spaghetti. Some how you connected a higher voltage to your 5s.

But hey, you didn't KFF and melt off a fingernail.

Yeah you may have hit the nail ont he head ill have to redo it again to prove that I did or didnt make a mistake. I very sure however I didnt but watch this space :SLOL!L!L

 

[adrock8519]

dnmun has a good thought there...

It is a subtle thing, where if you are not careful and connect a fully charged 5S and a partially charged 6S in series at say (4.2Vx5 + 3.8Vx6=43.8V) and then parallel that with another of the same configuration, except both 6S & 5S packs are fully charged (4.2x5 + 4.2x6=46.2V) then each 11S half will equalize to a common voltage of 45V, but then that means that the first 11S pack that started out at 43.8V has now overcharged the 5S pack by a couple tenths of a volt per cell. And of course, further charging will only exacerbate the problem.

Here is my suggestion:

take the packs apart and balance each pack (5S or 6S) one at a time to a common voltage. Storage Voltage would be best or about 3.85V per cell.

Then take the 6S Packs and parallel them together.
And Take the 5S packs and parallel them together.
Then Series connect the two larger packs.

Always parallel BEFORE Series, is how I like to do it.

Yeah good advice. I am sure they where all charged tot he same voltage. When Ive got time ill do a retest. Im was linking in series the voltage just to save on loom work.

 

[dogman dan]

Most plausible to me is somehow you mixed up a few packs, and had a 10s string connected to a 12s string.

Next, the possibility that you overcharged one of your strings some how.

I don't get it how an 11s string charged to 4.2v could charge another 11s string that was part discharged to more than 4.2v.

Perhaps you just had a break in one of the series connections, and in fact connected a 5s string to an 11s string? One plug partly pulled loose?

Tape em.