Is it OK to replace a Nickel Cadmium battery with a Nickel Metal Hydride battery of the same size and voltage? Will the charger know the difference?

 

These battery types charge at difference rates and they also have different "full" voltages. The chargers are not compatible, though there are chargers available that have a switch to go from NiCD to NiMH.

 

I always go with the manufacturers recommendation, to preserve the warranty

 

We have a Panasonic cordless phone that is several years old (out of warranty). It's not holding a charge very long and I went to get a replacement battery pack. Wally World had a large selection of batteries and I selected one that said it fits many phones by Panasonic. The battery pack is the same size and voltage as the previous one but the new one is Nickel Metal Hydride rated at 1100mAh whereas the old one is a Nickel Cadmium rated at 850mAh.

 

Do not use it. There should be a specific model or part number on the old battery, use this part number to find the replacement battery. The replacement battery should have a list of battery part numbers, or phone models that it can replace on it's package.

As airraid stated before Ni-Cad and Ni-MH charge differently so you will probably ruin the phone if you try to use that battery.

 

My R/C 7.2v batteries have a charger that switches between NiCD and NiMH. You should be able to find the right battery without too much trouble. Most retailers that carry Panasonic have their 800# for asking questions such as this. They could tell you how to get that battery if you can't on your own. When I worked at Target years ago we had a binder at the service counter full of the 800#s for each company we sold products for so that customers or employees could use it. If we had to deny a refund we could direct them to the manufacturer.

 

If you know someone electronic savvy, they can hook up some kinda of charger for you, out of your old base.

 

For more authoritive info see... http://www.primecell.com/nimhconv.htm or http://store.batteryspecialists.com/batteryinfo.html
Energizer also usually has an informative page. I have not read their latest revised page tho.

I am not a battery expert but have read or experienced the following...

NiMH and NiCad are different and charging all depends.

You can charge a NiMH in a NiCad charger but 1) you must time or monitor(voltage or temperature) the battery to make sure it is not "overcharged", this damages the cell a little or it could vent and kill itself. 2) NiMH likes a hard charge to start and then tapers off. "Dumb NiCad chargers charge at a relatively steady rate and may not "Punch" the NiMH hard enough to get a full charge, and they don't know when to stop. Usually if I hae a dumb charger I time the battery and check if it is warm to the hand. When it starts to warm up, the battery is charged and that is the rough amount of time you should charge in the future.

It's easier to just get a smart charger.

NiMH are starting to have better capacity, ie milliamp hours or mah, than NiCads. NiCad are usually much cheaper and have adequate capacity for many low to medium drain devices. NiMH are also supposed to be less prone to "memory" but my experience is that they fail just as often and similarly to NiCads.

I have noticed that the cheapie Chinese NoName NiMH batteries seem to fail more quickly than NiCads or "reputable" brands. I had one recent batch of about 10 Chinese specials where 2 failed in just a few months. Usually I can go a few years with a NiCad before I get shorted cells.

I have used NiCads and NiMH in the same devices with no real noticable differences except for the run time due to the milliamp hour rating. I have not tried either in a heavy drain application yet. I hear the NiMH are better for heavy loads like some cameras, flashlights and larger radios etc.

Good Luck,

Jim Henderson