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Charger for weird battery pack

kimbear

Member
I have a weird NiCad battery pack made up of 8- 1.2v 800ma AA batteries soldered together.
What power supply will I need to charge this correctly, and at what voltage??
If there is a EBay charger you can point me to, I would appreciate it.....something along the lines of:


Thanks a lot,
Kim
 
Last edited:

Externet

Active Member
I would say a 80ma capable charger that puts out between 10.4V and 11.2V should work.
 

rjenkinsgb

Well-Known Member
Most Helpful Member
You need at least 1.5V per cell, so 12V minimum for an eight-cell pack.
You only really need a dedicated charger if you must fast-charge them, as then the cutoff at full charge is critical.

If you do not need fast charge, just using 1/10th the MAH rating (so 80mA) as a charge current and leave it on for 14 - 16 hours minimum.
Leaving them on for a few hours longer is fine, it helps condition the cells.

The voltage in that case can be anything above the minimum, so eg. a 15V or 16V source such as a laptop charger.
Add a resistor so the current is no more than 80mA with 12V on the battery pack.
eg. with a 15V supply so 12V across the resistor, 3 / 0.080 = 37.5

A 39 ohm or two 75 ohm in parallel would be OK, just make sure the resistor has a decent power rating.


Edit:
Or if you want an off-the-shelf unit, one such as these would work:


 
Last edited:

Nigel Goodwin

Super Moderator
Most Helpful Member
I have a weird NiCad battery pack made up of 8- 1.2v 800ma AA batteries soldered together.
Not at all weird, 9.6V (8 cells) is a perfectly normal and very common battery pack - often used as the 8 cell battery cases were used to give 12V with non-rechargeable cells (for actual 12V with NiCd's you used 10 cells).

Here's a charger that has adjustable current, and does a wide range of cell numbers.

 

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