Sereis Parallel Electrical Question A bit Long

guido · Jul 24, 2015

Hello,
In the picture the new cells, and the circuit in question. The first two cell (1-2)are in series, the other two (3-4) are in parallel, you can see that by the polarity markings. 2 and 3 are barely connected at the top in series with 1 and 2 so I can get a voltage reading. They are lithium cells all about 4 volts each. From 1+ to 2- 8 volts. From 1+ to 3- third cell in series with 1 and 2 12 volts.
From 1+ to 4+ 8 volts,same voltage as from 1+ to 2-. If I put a load on all of them what will happen? Voltage at 1 and 2 is the same as 1 to 4, as if 3 and 4 are not there? Will 3 and 4 draw current like 1 and 2 when loaded?

Guido.

Bob · Jul 24, 2015

dr sportster · Jul 24, 2015

Sorta like in series with one reversed. Guido, what do you do with all these batteries besides battery experiments?

sotxbill · Jul 24, 2015

according to YOUR markings, cell 4 is reversed. However, did you check for sure? There is NO reason to reverse a cell in series. It will be forced into a reverse charge, over heat and possible catch fire.

Again, are you sure your markings are correct, if so, someone screwed up. Cells can be forced to take on a reversed charge so again be sure to check carefully and fix. Not good.

JMOR · Jul 24, 2015

(quoted from post at 16:31:15 07/24/15)
according to YOUR markings, cell 4 is reversed. However, did you check for sure? There is NO reason to reverse a cell in series. It will be forced into a reverse charge, over heat and possible catch fire.

Again, are you sure your markings are correct, if so, someone screwed up. Cells can be forced to take on a reversed charge so again be sure to check carefully and fix. Not good.

ven when wired correctly, the first one to go dead is forced into reverse charge by the others.

John T · Jul 24, 2015

The picture isn't perfect, but I dont see any parallel connections??? I see 4 as bass ackwards

John T

guido · Jul 24, 2015

Hello bob,

3 and 4 are parallel to each other, although are not connected on the plus side. They are is series with 1 and 2,

Guido.

guido · Jul 24, 2015

Hello sotxbill,

3 and 4 are spot welded negative to negative Look at the picture. I jumped them on the + side, and that is the voltage of the 2 in parallel,

Guido.

guido · Jul 24, 2015

Hello dr. sportster,

There were 3 sets of 2 in the pack I got. It was for a laptop. 2 sets of 2 were in series like 1 and 2. 3 and 4 were in parallel. Wish I had taken a look how they got the 10.7v with that setup. I use the cells to make up or repair drill pack, and usually give them away. This set when rated, and matched, will go into a pack like the one you see on the picture. That is a 5 cell pack, so I should be able to get 5 good ones out of the bunch,

Guido.

guido · Jul 24, 2015

Hello John T,

Negative tabs are together on 3 and 4.I was trying to put a 5 cell together for a drill pack. Those cells came out of a pack with two other sets of two, both is series like 1 and 2 on the picture,
Never seen that kind of setup. By the way, it was a brand new pack, in shrink wrap in the box it came in,

Guido.

teddy52food · Jul 24, 2015

I would cut that connection on 3-4 & after letting them lay for a few days see if they both hold the same voltage or if 4 is charging backwards.

Ralph, Ohio · Jul 24, 2015

Are you determining + & - ends of the cells by meter measurements or by some identification on the cells? In the pictures most of the + ends can be identified by the slight crimp near that end. I'm going to go out on a limb & say when the cells were arranged before welding that one cell was mistakenly put in backwards. There is no other logical explanation.

Ralph, Ohio · Jul 24, 2015

After looking at this picture I have another explanation. The external connections can't be seen but I think what you have is 2 sets of three cells. Each set of 3 is connected in series. 3 times approx. single cell voltage of 3.7 volts = 11.1 volts, close to the 10.7 you mentioned. In order to get more capacity, 2 sets of 3 cells are connected in parallel with the same resultant voltage but double the current capacity of a single set of three.

guido · Jul 24, 2015

Hello Ralph,

There are three sets of cells, two are in series and one in parallel. What the cells may have been configured is those two series sets in series, one cell in series with each of the parallel cells, then both sets parallel. That would make sense. I never looked how they were tied, as I need to make a 5 pack in series for a drill pack. The cells are 2600Ma 3.7
Volts. That would give me 18.5 volts. The old pack had 5 1500Ma cells at 3.6volts or 18volts. As you can see it will be a much better pack when done,

Guido.

guido · Jul 24, 2015

Hello teddy52food,

Read my reply to Ralph in Ohio. It will explain what I am doing with cells
I May just hard solder them as they are load them up.and check the voltages on all the cells,
Guido.

sotxbill · Jul 25, 2015

shows to be overcharged. Was it just charged?

CKain(MI) · Jul 26, 2015

I agree with that !

guido · Jul 26, 2015

Hello Ralph,

1 and 2 in series, 3 and 4 in parallel,

Guido.

guido · Jul 26, 2015

Hello ckain (MI),

Look at the picture, the only Positive post is the bottom of #2. Notice the white insulator disk on that cell?,

Guido.

ss55 · Jul 27, 2015

The answer is?

guido · Jul 27, 2015

Hello ss55,

I will post the results, as soon as I get a chance. I'm not sure of a load I need to use. I'm thinking maybe twice the amp rating of the cells. I just need to see how many ohms it will take once I measure the voltage.I will charge the cells individually, to the same state of charge, so they will be all the same capacity. Stay tuned..............

Guido.

Sereis Parallel Electrical Question A bit Long

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