Replacing battery cells in an old battery pack

MichaelWeaser

Newly Enlightened
Joined
May 18, 2017
Messages
6
I was told on another forum to post on here any question I have about batteries . since what i have been told is people on here know a lot about batteries.

I need to replace the NiMh cells in this battery pack. The pack is for an old laptop around 1999 or so. The only thing i know is the battery pack is 7.2V and can have a capacity of 4000 or 4400 MAH, and it has 6 cells. I was thinking by the picture it used AA cells , but if the pack is 7.2 volts the cells would be in series and I'm sure AA NiMh aren't available in 4000 or 4400 MAH , The pack could be 4000 or 4400 mah if the cells where 3 batteries in series and than another 3 in series than in parallel. So I believe they are C cells, but i'm not totally sure since I think the battery pack is too small for C cells but I might be Wrong. Also whatever the pack uses I will need to pick what brand of cells to use , I know what to use if they are indeed AA cells I know to use eneloop batteries but I wouldn't know what to use if they are C cells, I do believe C size eneloop batteries do exist. So if anyone can help me figure out the cell type that pack uses and what brand to use that would be great.
nec--h350ae-6nec_MAIN_1.jpg
 

Kestrel

Flashaholic
Joined
Oct 31, 2007
Messages
7,355
Location
Willamette Valley, OR
Am certainly no expert on these (there are others here who disassemble older battery packs); but if you're not able to crack it open to get individual cell dimensions, at least getting accurate outside dimensions would be a good first step. Best of luck,
 

MichaelWeaser

Newly Enlightened
Joined
May 18, 2017
Messages
6
I was told on another forum to post on here any question I have about batteries . since what i have been told is people on here know a lot about batteries.

I need to replace the NiMh cells in this battery pack. The pack is for an old laptop around 1999 or so. The only thing i know is the battery pack is 7.2V and can have a capacity of 4000 or 4400 MAH, and it has 6 cells. I was thinking by the picture it used AA cells , but if the pack is 7.2 volts the cells would be in series and I'm sure AA NiMh aren't available in 4000 or 4400 MAH , The pack could be 4000 or 4400 mah if the cells where 3 batteries in series and than another 3 in series than in parallel. So I believe they are C cells, but i'm not totally sure since I think the battery pack is too small for C cells but I might be Wrong. Also whatever the pack uses I will need to pick what brand of cells to use , I know what to use if they are indeed AA cells I know to use eneloop batteries but I wouldn't know what to use if they are C cells, I do believe C size eneloop batteries do exist. So if anyone can help me figure out the cell type that pack uses and what brand to use that would be great.
nec--h350ae-6nec_MAIN_1.jpg

I was thinking and doing some research it might not use C or AA cells , It might use a smaller version of C cells called Sub-C which is less thick and also they are available in 4400 mah which is the capacity of the pack.
 

alpg88

Flashlight Enthusiast
Joined
Apr 19, 2005
Messages
5,282
nimh packs are never wired in parallel at a factory, since it confuses smart chargers.

looking at size and shape it is most likely 7\5 A cell, which is the same size as 18650
 
Last edited:

Lynx_Arc

Flashaholic
Joined
Oct 1, 2004
Messages
11,212
Location
Tulsa,OK
You probably won't be able to use eneloops in this pack unless you can fit 12AAs in it in series/parallel and it is quite possible you have odd C cell sized batteries in it like 4/3C or SubC cells which neither are available in LSD I've looked for years for a subC LSD cell with no luck. One thing that would take some doing is to build an 18650 based battery pack for it as 7.2v nimh is equal to 2 18650s in series so a set of 4 batteries in series/parallel would add up to even more capacity you could use 3000mah cells and make a pack with 6000mah capacity the only problem is you may have to have someone weld the batteries together for you and design a charging system for it but you can buy circuit boards and chargers to suffice.
 

MichaelWeaser

Newly Enlightened
Joined
May 18, 2017
Messages
6
nimh packs are never wired in parallel at a factory, since it confuses smart chargers.

looking at size and shape it is most likely 7\5 A cell, which is the same size as 18650

I never knew that 18650 cells in Nimh exist , and I can't find them anywhere. But is it possible for the cell size to be Sub-C which are slightly thinner than C batteries. If you send me a link to show me that 18650 cells exist in NiMh that would be great.
 

Lynx_Arc

Flashaholic
Joined
Oct 1, 2004
Messages
11,212
Location
Tulsa,OK
I never knew that 18650 cells in Nimh exist , and I can't find them anywhere. But is it possible for the cell size to be Sub-C which are slightly thinner than C batteries. If you send me a link to show me that 18650 cells exist in NiMh that would be great.
Without truly knowing the dimensions it could definitely use A type cells
http://batteriesplus.co.uk/acatalog/7-5AF-5-4A-4-3AF-4-3A-Size-NiMH-Battery-3700mAh-1250.html
This battery is a 17660 which is close to the size of an 18650.
 

MichaelWeaser

Newly Enlightened
Joined
May 18, 2017
Messages
6
Without truly knowing the dimensions it could definitely use A type cells
http://batteriesplus.co.uk/acatalog/7-5AF-5-4A-4-3AF-4-3A-Size-NiMH-Battery-3700mAh-1250.html
This battery is a 17660 which is close to the size of an 18650.

the battery pack was originally 3900 Mah and now you get the cells redone with 4400 mah batteries , I can't find 4400Mah version of those batteries. I need to get the measurements of the pack but I don't have the pack right now since the pack is my friends and i'm doing it for him.
 

MichaelWeaser

Newly Enlightened
Joined
May 18, 2017
Messages
6
Without truly knowing the dimensions it could definitely use A type cells
http://batteriesplus.co.uk/acatalog/7-5AF-5-4A-4-3AF-4-3A-Size-NiMH-Battery-3700mAh-1250.html
This battery is a 17660 which is close to the size of an 18650.

Finally figured out what the cells are , I contacted the original manufacturer of the battery which no longer makes them. They told me they use 4/3A which is also known as 7/5A cells which are almost identical to 18650 cells , on what they have told me.
http://www.batteryspace.com/nimhrechargeablecell43a12v3800mah1pc.aspx
 
Top