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

[Jim Stone]

Thanks, David.  I hadn’t noticed that the Amazon replacement was Ni-MH.  I know a little bit about Li-Ion and Ni-Cad batteries but nothing about Ni-MH.  Does the fact that the replacements would be Ni-MH have any impact on my rebuild vs. buy decision?

Jim

> 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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