After a couple days of evaluation, here's what I've found:
1. I DO NOT, recomend that you try this method with batteries, as your power source, for a couple reasons.
- One 6min. charge will basically kill 2 AAAs, for practical use anyways, that could get expensive.
- Once the batteries become weak, charge rate becomes more erractic, making it harder to judge when the voltage is done dropping.
for those 2 reason I think it would be better to use a 3 volt power adapter. I have a cigar box full of AAAs, so I will continue my testing with batteries, until my box is gone.
2. The voltage going to the battery being charged does affect how much the battery will draw. Chargeing with fresh batteries will push 1.85-1.90 volts, Where as drained batteries only push 1.70-1.75 volts
3. No matter what charge voltage the batteries are taking, they always read 1.38 when done.
4. Once the voltage drops below 1.5 on the AAAs, it takes nearly twice as long to charge. One 3min. charge on the 50mah battery will pull the voltage of the 2 batteries down to 2.94. Which makes me think after about 4 charges on a ZIp Zap controller, you are not filling your battery as much as before. I'm sure you could get more charges from a controller with AAs.
5. The first couple times the NiMH had a more erractic charge rate than the NiCd, which, as long as I use fresh batteries, consistantly rises to 1.85 volts, then slowly drops to 1.74. The discharge rate seem to reflect the charge rate. The NiMH seem to wind down in steps, where as the NiCd would gradually wind down just like it charged. I decided to get voltage readings every 5 min. to try to illustrate this, BUT this time the NiMH jumped to 1.85, stayed at 1.85, when to 1.87 for a sec. and then slowly dropped to 1.74. much more consistant that it was before, and the runtime voltages reflect that. Which partially proved my theory, but i wish the NiMH would have charges erractically one more time so I could see what was going on while it was running.
Here's the voltages:
min. NiCd NiMH
00 1.38 1.38
05 1.26 1.27
10 1.23 1.27
15 1.21 1.22
20 ---- 1.22
25 ---- 1.21
30 ---- 1.22
For some odd reason the NiMH had 1/100 volt more after the battery died.
Hope this information helps anyone.
Dave