Can you remove 2 cells from an 8 cell laptop battery and have it function off of the remaining 6?

[Spurst]

Already tried the laptop forum. I guess it was too technical for em. =/

I have a dead laptop battery out of an inspiron 26xx (I think 41xx fits too). After testing it, I've concluded that 2 cells are stone cold dead and it is causing some serious issues with the battery. IE the battery power indicator no long displays anything and the battery refuses to hold a charge. Now, my question to you; can I remove the 2 extra cells and complete the circuit path to still have the battery function as normal?

I am not worried about battery time, as long as it is greater than 10 minutes so we can move the laptop from one plug to another.

They (Dell) sell a 6 cell version of this battery. The 8 cell gives longer life as it draws from more cells. However, I am asking if I can take an 8 cell battery and remove 2 dead cells in order to utilize it as a 6 cell battery without any negative effects other than shortened charge length.

 

[Matthias99]

From a sheer 'get some kind of electrical power out of it' standpoint, I think that could work.

Obvious problems that could occur:

1) The charging circuitry may expect there to be 8 cells present. The laptop may try to overcharge the battery if you remove some of them.

2) Depending on how the battery is designed, you may get a significantly lower output voltage with fewer cells. I don't know if the laptop itself has circuitry to correct for this, or if that is built into the battery -- and in the latter case, it may be designed to deal with only relatively small fluctuations, not with 25% of the battery being removed/dead.

 

[bobsmith1492]

Hm, the Sony batteries burned because of some charge circuit defect, right?

Due to the inherent problems with Lithium cells (assuming it's a LiON pack, right?), I wouldn't touch it. The charging circuitry has to be just right...

You could experiment, though - just wire to the battery remotely (NOT in your laptop) and see what happens.

 

[imported_Seer]

You're asking for trouble. As Matthias said, these are "smart' batteries, not just some cells strung together in serial / parallel. I wouldn't expect it to function at all in such a state.

 

[Spurst]

Well, what if I just replace the dead cells? The cells might simply have died due to age.

 

[darthsidious]

I highly recommend against doing this. Li-Ion batteries are very sensitive to charging currents, and messing about with the number of cells seems like a good way of getting them to expolde (which Li-Ion batteries are prone to do if they are mistreated, which is why they have a lot of protection circuitry while charging ).

Most likely, the "smart" circuitry will detect something is amiss, and not charge. Regradless, I feel that this isn't a risk worth taking. Just buy a new battery...

 

[StopSign]

By all means, crack open the battery case and take out a few cells! They should power a flashlight nicely.

 

[pm]

Taking out two cells won't work. An 8 cell laptop battery is probably hooked up as a 4s2p pack (4 series of 2 parallel cells). It is probably set up as a 14.4V (nominal) pack (4s = 3.6V * 4). If you removed two cells from each of the two parallel packs, you'd lower the voltage to 11.1V (nominal). This would be under the lower voltage battery cut-off for the laptop. If you you took two cells from one of the two parallel sets, you'd have a 14.4V pack and a 7.2V pack - which would do nothing and would probably mess the charger up. You could take out 4 cells and leave it as one 14.4V pack, but this would cut the battery life in half, and could cause problems due to excessive discharge rates.

If you are really keen on swapping out the cells, then I would buy replacements at www.batteryspace.com, or www.all-battery.com. Match them closely with what you currently have.

But I would recommend just buying a new battery pack. It's safer and will work better over the long term than swapping in two fresh cells into an old pack.

 

[randay]

Originally posted by: pm
Taking out two cells won't work. An 8 cell laptop battery is probably hooked up as a 4s2p pack (4 series of 2 parallel cells). It is probably set up as a 14.4V (nominal) pack (4s = 3.6V * 4). If you removed two cells from each of the two parallel packs, you'd lower the voltage to 11.1V (nominal). This would be under the lower voltage battery cut-off for the laptop. If you you took two cells from one of the two parallel sets, you'd have a 14.4V pack and a 7.2V pack - which would do nothing and would probably mess the charger up. You could take out 4 cells and leave it as one 14.4V pack, but this would cut the battery life in half, and could cause problems due to excessive discharge rates.

If you are really keen on swapping out the cells, then I would buy replacements at www.batteryspace.com, or www.all-battery.com. Match them closely with what you currently have.

But I would recommend just buying a new battery pack. It's safer and will work better over the long term than swapping in two fresh cells into an old pack.

Yes just replace the cells or buy a new battery pack.

 

[Xdreamer]

it would depend on if the cells are arranged in series or in parrallel. If they are only in parrallel the voltage will be the same but the current will be less

 

[sao123]

just buy a replacement battery from ebay?

 

[Spurst]

Well, I was hoping to not have to go that route as the rest of the cells work fine. I'd be okay with 10 minutes worth of battery. I literally just need enough charge to move the unit from one wall to the other.