NiMH Activ Energy Smart Charger (So Called)

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kennybobby's picture
Last seen: 20 min 23 sec ago
Joined: 05/10/2017 - 09:13
Posts: 945
Location: huntspatch, alabama
NiMH Activ Energy Smart Charger (So Called)

if you like having your cells roasted.

This was the first cycle session on some 1400 mAh AA NiMH purchased earlier this year. They came precharged at about 1.3V and were put into an LED lamp used to provide task lighting near the computer. After a couple of months the light was dim as the cells were discharged.

So i put them in the 4W (2× 2.8V@300mA on the label) four-cell Smart Charger and set a timer to check on them in :30, and they were cool to the touch. At 1 hr the same result, also at 2 hrs and 3 hrs. Then i got lazy and had a brain fart at just the time that due diligence should have been exercised, i.e. more frequent checks should have been done instead of fewer. Since i had found no noticeable temperature increase over 3 hours, i doubled the timer to make the next check at 6 hrs Facepalm Facepalm Facepalm dumb move for sure.

Now the cells were hotter than could be touched or held. The voltage was at 1.42 for all the cells—they were fully charged and scary hot! The Smart Charger was still indicating charge mode and never changed from amber to green to indicate end of charge..?

The internals of the charger didn’t show any damage and the main control ic had the part number etched off, so no reverse engineering was attempted.

so i wonder how much life gets lost when you cook the NiMH cells in this so-called Smart charger…

Now i used to think that i was cool,
drivin' around on fossil fuel,
until i saw what i was doin',
was drivin' down the road to ruin. --JT

Lightbringer's picture
Last seen: 26 min 7 sec ago
Joined: 08/30/2016 - 14:12
Posts: 15733
Location: nyc

Probably quite a bit. I had NiCd cells start to fizz and stink like vinegar when they overcooked. Got like only half the runtime on my Walkperson after that.

They should vent then reseal if overcooked, vs popping like a balloon.

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