Category Archives: Battery Rebuilding

Quickie 1-cell discharger

Wow – I wasn’t planning to make this.  But as I fantasized about just building a simple discharger while struggling with 1-cell problem on the big 18 cell discharge tester, it sounded too simple to resist.  I could get to … Continue reading

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Battery discharger problem with 1 cell

The big battery discharger works well (or so I thought) except for the case of testing single 1.xV cells.  It just doesn’t work – reporting 0V often.  There’s even a comment in the code dated 2/15/11 (right under the V1.3 … Continue reading

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Dell laptop battery test / rebuild

My dear (7 year) old Dell Inspiron 700m with extra capacity 8 cell battery has been running out of battery more quickly than I think it used to.  Since Bob G recently bequeathed a couple of laptop batteries to me, … Continue reading

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Ryobi battery rebuild with more learning opportunities

My 14 year old 12V cordless drill is finally back on the air, with a battery pack rebuilt for the manyth time.  Two more cells replaced this time, but once again, some surprises.  I remember when I thought the hard … Continue reading

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Trickle current limiter for B&D charger

I’ve worried for years that at least some of the NiCd chargers’ trickle charge regimen was cooking my batteries into oblivion.  They say you can charge sub-C NiCds at 100mA forever without problem, but for stuff that’s charging for months … Continue reading

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Battery tab welder has foot pedal and charger cutoff

Faced with a potentially large number of welds for rebuilding a DeWalt battery, I finally integrated two improvements that have been waiting in the wings:  a MOSFET charger disconnect and a foot pedal to disconnect the charger and fire the … Continue reading

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DeWalt battery rebuild

What better birthday gift for my friend Ed than a handmade rebuilt 18V DeWalt battery made from recycled sub-C cells?  OK, especially when he provided 2 of the old packs I scavenged from. In addition to Ed’s donations, Mike D … Continue reading

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Welder foot switch

I put the foot switch together entirely from scrap.  I found 2 microswitches on a little bracket, a scrap of paneling, and old hinge, a block of wood and some closed-cell foam for a spring.  The wire is a scrap … Continue reading

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Welder is taking shape

An old battery charger, re-purposed as the charging supply for the welder is rewired and functional.  With thanks to some correspondence from Bob Van Valzah, I went with the dual half-wave arrangement using the center tap to get one diode-drop … Continue reading

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Improved battery discharger current accuracy

I swapped in a 0.9Ω resistor for the old 0.1Ω current sense resistor, giving 9X better current accuracy without reducing the 2A design max discharge current.  The original was just a poor choice. Since that resistor will dissipate 9X more … Continue reading

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