I have a charger which was originally untended to charge NiCd batteries. I want to fully charge some of the NiHM batteries in my solar yard lights. While the solar charger normally charges them, it likely never gets them fully charged. I think they should be brought up to full charge at least a few times each year.
If they need a special charger (made for NiHM), where can they be purchased? (Such as Walmart, Radio Shack, Hardware Stores, other local stores), since I prefer to avoid online shopping.
I sometimes can be a bit stupid concerning electronics, (if it doesn't work, either it's not plugged in or someone didn't pay the electric bill) electrons are electrons, no matter what the source. (unless you're using a positron based battery system) STG
It depends on what you are expecting from the charger and the lifetime you expect from the cells ("batteries").
A charger designed for NiCd's will typically *cook* a NiMH cell -- it just "doesn't know when to stop".
Most (new) NiMH chargers can also handle the NiCd cell chemistry.
A "dumb" charger (i.e., a resistor in series with a voltage source) will typically cook ANY battery (unless the voltage source happens to be lower than the cell voltage -- in which case, it simply won't COMPLETELY charge the cell). Some are timer controlled (they just "charge" for a fixed length of time and "hope for the best"). Obviously, you can see how reintroducing the battery tot he charger before the battery has "worked off" that previous charge will eventually result in the battery being increasingly (over)charged. Likewise, returning the battery to the charger after MORE than that amount of charge has been withdrawn means the battery will never be "topped off".
Beware - putting NiMH into older NiCad chargers may fry the batteries ! .. they may emit a popping / boiling sound and a certain odor .. not that my wife has ever done that - but .. read the small print on the charger. I currently use a little charger that will charge both - not an expensive item at all .. John T.
Each battery chemistry has a different ideal charging regimen. A Nimh charger will charge nicads afely, but a nicad charger is not recommended for Nimh.
You've been given good advice on chargers. Now, some advice on your objective. Forget it and go do something you enjoy. If you insist on charging the cells in THAT APPLICATION twice a year, use the voltage source and resistor to set the current to about 1/10th the mah rating of the cells and only charge for 10 hours or so.
BUT
You're probably better off watching a fun movie instead.
Thanks. That is what I wanted to find out. I'll just get a NIMH charger for both types. Actually, most of the solar lights I have taken apart have had NiCd batteries in them. Which explains why they dont last long, because the NiCd batteries retain memory, and they dont always get charged fully on cloudy days.
Using the advice from a website that sells these solar lights and replacement batteries, they have a detailed article that says that it's best to replace with NIMH. (A little more costly, but much longer life and they do not have that memory issue).
In many cases the battery costs more than the solar light, so its cheaper to just buy a new light, but I have a few that I paid bigger money for, and a few more "fancy ones" that can not be replaced because they are no longer sold. Those are the ones in which I replace the batteries.
One thing I learned, is that to test the fixtures, I can put a standard carbon zinc or alkaline battery (AA or AAA) in a fixture, to see if the LED lights. Of course those are not rechargable batteries, so they can not be left in the fixture. But that's a quick way to test the fixture. Actually, I have never had any fixture that did not work (except those that had physical damage from fallen objects or other accidents). Otherwise, its always the battery that fails.
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