Brand new Sanyo 2300 NiMH.
Instead of using my Hobbico field charger at its lowest setting of .2 amps I want to use my old wall TX RX wall charger at 50 milliamps.

The charger says its for Nicads.. is it safe to use for my NiMH??

am I correct here?

wall charger at 50 milliamps is 1/4 of the lowest charge on my Field charger which is .2 amps??

Its best, especially for the first charge, to charge low and slow?
I'll charge the 1st time for 46 hours on the wall charger, after that I'll use the lowest setting on the field charger???

Steve

If the charger works for NIMH, then it will work for Nicad. Not necessarily the other way around.

You are right that 50ma is 1/4 of 200ma or .2 amps.

To figure out initial charge time, take the capacity of the battery, multiply by 1.4 (for losses) and divide by charge rate.

So, 2.3x1.4/.05=64.4 hours

You can safely charge it with either charger but if you want to do the long slow charge with your wall charger, go for it. It will definitely work and help insure that you don't charge it too fast.

Why not use the Hobbico Charger? .2 amps is 1/10 C for that battery, which is a very acceptable charging rate. You may find that the wal-wart charger will take even longer than the 64 hours the math shows.

Brad

How long would that take to charge a new battery?
The problem with the hobbico charger is that it shuts off after 2 hours.

I'd prefer to use the hobbico as I can hook up a meter and monitor the progress.
I'm just not sure how low is considered good for the 1st charge? I know a low charge is better.

Pop, read this excerpt from Hang Time Hobbies.

Q: What's up with 'Formation Charging'? Can't I just charge and fly a new pack?

A: The term 'Formation Charging' describes the initial charge/discharge 'forming' process that fully activates the 'chemical engine' and balances the cells in a new pack. NiMH packs have a particular need for repetitive c/10 charge/cycle conditioning, a 'break-in' procedure needed to get them to full rated capacity. Both NiMH and Nicad packs benefit from the process and the intent is to make sure that any new pack has been verified to be fully operational and that a 'start-up' capacity number is established for the pack before it's put into service. To 'Form' a new NiMH pack do three 10% 16-24 hour charges followed by a 300 to 500 ma discharge routine between each charge. In other words: Do a slow charge at the slow charge rate (or as close to it as you can reasonably get with your equipment) as shown on the pack label. Charge till the pack is warm, followed by a controlled discharge with a cycler. Do it 3 times. The recommended Formation Charge/ Slow Charge rate for our packs is printed right on the label of the pack as well as on the data card the pack was shipped with. New Nicad packs should get at least one slow charge followed by a 300 to 500ma discharge. Record the capacity numbers reported by your equipment for comparison cycling as the pack ages. Never check your brain at the door! As one respected modeler put it, "There's nothing more suspect than a new battery pack." Before you fly anybody's pack be certain it's fully operational and safe to fly.

Birman