[Shop-talk] Rebuilding a Battery Pack vs Buying New Generic

Thu Jun 26 20:37:58 MDT 2025

Jim,

For what it's worth, in case you decide to rebuild, I have rebuilt 
battery packs for my obsolete Craftsman 12 volt drill,
and the battery packs for my old Sunpak high voltage camera flash units. 
All of these originals were made with NiCd batteries and I've used NiMH 
with great success. I source the batteries from ONLYBATTERIES.COM. The 
great advantage to the rebuild route is I get to select higher capacity 
batteries than the originals. They take longer to charge with the 
original chargers but last enough longer in the devices to make it 
worthwhile. This has been an incredible advantage in using the camera 
flash unit. The Sunpak packs uses low voltage sub c or AA sizes, 
depending on when they were made, to operate an oscillator circuit to 
generate a 510 volt equivalent for the flash.

In my case, the original types are not available anywhere so rebuilding 
was my only choice.

Jim

On 6/26/2025 8:13 PM, Jim Stone wrote:
> Thanks, David.  The Amazon listing indicates compatibility with the 
> original charger and several reviews say they had no trouble doing so. 
>  It is a $40-$50 gamble either way and I have too many projects at the 
> moment to add rebuilding a battery pack to the mix.  I will give the 
> Amazon pack a try and report back.
>
> Jim
>
> p.s. I switched to Milwaukee battery tools, as well.  I started with 
> the M12 set and then added M18’s as well.  I especially like the fact 
> that one charger will charge both the 12v and 18v batteries.  I still 
> have some of my old tools and have bought a couple of adaptors to be 
> able to continue using a few of them with the M18 batteries.  They are 
> reasonably inexpensive and work very well.  I wish I could do that 
> with the Bosch saw, but no one make one and, while I could probably 
> rig something using the old pack, I don't want to risk burning out the 
> motor running it at only 18 volts.
>
>> On Jun 25, 2025, at 7:48 AM, DAVID MASSEY <dave1massey at cs.com> wrote:
>>
>> I used to have an old Makita drill that came with Ni-Cad a battery 
>> that eventually stopped being usable.  I bought a pair of 
>> lithium-based replacement batteries.  On the surface they looked like 
>> a much better option with double the capacity and they worked with 
>> existing drill and charger.  But (there's always a but, isn't there?) 
>> to make Lithium batteries work in a Ni-Cad environment required a 
>> electronic circuit and this circuit was always on and drew enough 
>> power to deplete the battery overnight.  I could charge them up in 
>> the evening and the next morning they would be close to dead.
>>
>> But I see these are Nickel-Metal Hydride batteries.  Ni-MH batteries 
>> have characteristics more similar to Lithium - at least with regards 
>> to the charging regime (I've designed a battery charger for Ni-MH so 
>> I am familiar with this) but are less susceptible to abuse.  I also 
>> see the bullet point about no self-discharge - which was my problem. 
>> This is a $45 gamble (as it is with most no-name stuff from the 
>> Pacific rim) but YMMV.  This might be a good one.  Let us know.
>>
>> BTW I bought a pair of Milwaukee 12V tools and never looked back.  I 
>> pitched all my Ni-Cad drills and recycled the batteries.
>>
>> Dave
>>
>>
>>
>>
>> On Tuesday, June 24, 2025 at 01:36:47 PM CDT, Jim Stone 
>> <1789alpine at gmail.com> wrote:
>>
>>
>> I have an old Bosch 24v miter saw that I would like to be able to 
>> continue using for quick, non critical cuts.  The only problem is 
>> that the NiCad batteries won’t hold a charge long enough to be 
>> useful. And, I don’t think there is a way to utilize other, e.g. 
>> Milwaukee M18, batteries in a 24v system.  Besides, there don’t 
>> appear to be any adaptors available.
>>
>> So, that leaves me with two choices: rebuild my current batteries or 
>> buy new ones on Amazon.  I’ve taken one of the battery packs apart 
>> and can see that it just uses standard Sub C 1.2v batteries - 20 of 
>> them!  I’ve never rebuilt battery packs but it looks pretty straight 
>> forward; just time consuming.  20 Sub C batteries would run me about 
>> $40-50.  (Having it done professionally looks to cost at least twice 
>> that.)  Or, I could just buy a Chinese-made replacement pack for just 
>> a few bucks more. 
>>  (https://www.amazon.com/Exmate-Replacement-Battery-Compatible-BH-2424/dp/B073Z9QHXS/ref=sr_1_17). 
>>
>>
>> I’m sure the replacement batteries are also made in China, but is 
>> there any reason to assume that rebuilding the packs myself will 
>> result in a better, longer lasting battery?  Any advice from those 
>> who have done this before will be much appreciated.
>>
>> Thanks,
>> Jim
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