Well, I'm "something" to this forum. Not sure I'd say a credit.
I just happened yesterday to be cycling an old 1000ma nicad 8 cell pack and this refreshed my memory on a few things. I've got one of those cheap Harbor Tool & Freight solar charged motion spot lights on my garage and the pack it came with was a dud from the start last year when I bought the thing. I hitched up a charge plug to it's solar panel voltage input and cycled it about five times to try to get the pack to hold more capacity. Nothing doing, as the light would die after about the 2nd or 3rd time it lit up every night, even if I fully charged it via my charger to see if perhaps it just wasn't getting enough energy during the day from the solar panel to keep it topped off.
So, yesterday I took it down and took the thing apart to see just what kind of pack it had inside, which was never really meant to be removed or changed. Low and behold it had a 5 cell Sub C Nicad in it that was rated at 1300ma. Yea right, it would be lucky to hold 400ma. A few wire snips later I had the pack removed for replacement. I don't have any Sub Cs laying around doing nothing at the moment so I dug into my metal battery box and found an 1000ma 8AA Nicad pack meant for RC cars that somebody gave me a few years back.
OK, that should work, since I know these AAs can probably handle the high amp draw the Sub Cs were meant for when the halogen light comes on from motion. I'll have to break the pack down to 5 cells and re solder the cells into a configuration that will fit inside the motion light, but before doing that I figured I better make sure these cells are still good which meant time to cycle them about 3 times to check that and also to excercise them to hold the highest capacity.
First thing I did was to charge the pack. I used .5 amps for about a two hour charge rate and set the m/v setting to 12. Once fully charged I picked the discharge function and set that at 1 amp and the target voltage at .1 volts. Since this charger is only 5 watts it could only get to I think about .5 amps discharge with the fully charged pack (.5 amps times roughly 10V= 5 watts). As the battery drops in voltage the amp rate will climb higher because amps x voltage=watts. What I forgot is that as the pack gets really low the charger will once again lower the amp draw (mine was showing .0 amps) near the end so that the pack can maintain a more "true" voltage for the charger to monitor. IE: If the charger was trying to draw 1 amp out of the pack when near dead the battery voltage will sag and get down to .1 volts under the load while still not getting all the juice drained out of it.
For the above reasons the discharge took a long time to do completely. If you don't have the time to put into something like this then just hitch the pack up to a 12V car light bulb of some sort. That will suck the charge out of it much faster. I always use a bulb anyway when trying to recover a pack (see details posted in this or one of the other linked threads) to make sure the thing is dead as dead. Not as important on a new pack you are just cycling to excercise.
I plan to re-charge the pack at .5 amps (about two hours) and drain it (car light bulb) two more times for a total of three cycles to flex it's muscles (hold a higher capacity) as much as possible. Once I'm sure it's a good pack (with say anything above 1000ma put back into it on each charge) I'll break it down and reconfigure into a 5 cell and solder that puppy into the motion light. First drain down and then recharge at .5 amps showed 1005ma put back into the pack. That's a good start, and I bet once it's cycled a few more times it will hold somewhere in the 1300 to 1600ma range as healthy cells usually hold 300 to 700 more MA than they are rated for in a nimh or nicad.
So, what's all this mean to you? Well, Kered said anything about .7 amps will pop the thermistor unless the pack is kept cool (ice pack or a fan on it when charging). You don't want to go that high anyway when conditioning the pack when new like this, so I'd do this: First two charges I'd charge it about about a 10 hour charge time (130ma) and discharge on the charger at .5 amps or lower to be easy on it. 3rd cycle I'd charge it at 650ma for a two hour charge rate and drain on a car light bulb to speed things up. Do that at least once (3rd cycle) or better yet another 2 cycles for a total of five total with all the above steps. Write down your MA number with each charge and note how the pack holds more and more capacity with each cycle. If cycle #5 is still showing more progress than #4 then you might want to cycle it a few more times to gain the maximum improvement. That's why I say if you think the charger false terminated write down the MA put in and then add that to the re-started capacity it chargers to.
Also, while I'm thinking of it, if you think the pack false peaked and you decide to up the m/v setting by a few digits don't put it back on the charger for about ten minutes. Why? Because this will give the pack time to settle in voltage so that if it is peaked the charger will "see" the voltage drop when it's trying to re-peak it. For instance, if the pack is fully charged but you put it right back on the charger within minutes to see if it will hold more charge the voltage "drop" from it being peaked already won't settle. It's already hit that "wall" and so you might not see the proper voltage drop throwing it right back on because it's already "stuck" at that voltage from reaching peak. By letting it sit for ten minutes or so the pack will settle down and so once again should show "I'm peaked and dropping in voltage from overcharging" once it's thrown back on. Normally if a pack can't handle more charge it will self terminate within about 30 minutes.
The safest thing to do is watch the voltage for about 7 or 8 minutes on the screen as it charges. Is it climbing any more even at least by a digit or two? Then chances are it's still not reached it's peak. Write down the voltage and pay it another visit in say twenty minutes. Is the voltage now higher? It's still charging then. Check in another 20. Is it still yet higher? For sure it's not reached peak yet and all is probably well. Is the voltage now lower or staying in place to what is was 20 minutes ago? Come back in another 15 or 20 minutes and take a look at it again. Has it climbed some or is still staying the same or lower, or only raised by one digit? It might have already peaked and the charger missed that. Wait another 15 minutes or so and look again. That's how picky I get when I think my m/v setting is too high and the charger has missed the peak.
That's a quick and dirty way to watch the charge on a charger with no display or other peak indicators. Hitch up a volt meter at the battery while it's charging and just watch the screen here and there to see when it's no longer climbing in voltage.
Please remember this info is battery specific. Lipos should NEVER be drained below 3V per cell and nimhs should have the m/v set around 6 or 7.
My brother had one and he named it the"Millenium Falcon" after the spaceship (off Starwars or some film) not because it was incredibly fast though!
Really, I knew a guy in the 80's who owned one (a Yugo, if I have to point that out) and he claimed it was pretty darn fast once he took off anything that was unneeded weight.
, along with some connectors.