Tonedeaf,
That ebay link is now dead. what type of charger were you talking about?
It's called an Imax B6 charger, so just seach ebay and you should get a zillion hits. Cost should be between $30 and $40. I use mine to death and absolutely
love it (although a couple of buttons have fallen off of mine, but I get around that easy enough).
Like I said before, the manual is a little rough. There's a small learning curve involved since basically what you're doing is taking all chargers and putting them into one.
I can help you out if you decide to buy this charger and can't figure out how to use it, but you basically just use the left button to select the battery chemistry (Lipo, NiMH, pb, etc) and the other buttons to toggle through menu selections, which enable you to set the charge amperage and, in some cases, the charge voltage. It's not completely random...the menu has presets based on specific battery chemistry, but you do need to know some what you're doing because it's possible to re-charge a battery too quickly and cause damage due to overheating if you choose too large of an amp setting for the specific size battery...read on because I address a couple of simple precautions on ways to prevent this later in this post.
Anyway, the basic concept of the charger is that you first choose a chemistry. The charger then has automtic pre-sets for the voltage based on the battery chemsitry. You then choose the amperage based on the size of the battery. For some battery chemistries, like lead, you have to know the number of cells in the battery in order to get a correct voltage. Then amperage can be adjusted based on the desired re-charge time. It turns out that SLA cells are approximately 2v each, so a 6 volt SLA has 3 cells and a 12v SLA has 6 cells...the number of cells in one of the menu choices when you're setting the charger up for SLA charging. For any battery chemistry, you set whatever amperage you want (up to 5A) in order to determine how fast you want the batteries to re-charge.
The four buttons on the charger allow you to step through all of the various menu selections and once you have the charger selected to all of the settings you want, you press and hold the right most button to start recharging. The charger then tells how far along you are in terms of how many mah have been put into the battery.
As it's recharging, you can tell charging progress...or how 'full' the battery is...as it's being charged if you know, for example, the capacity of the battery and how far dicharged it was before you put it on the charger. So, for example, if you have a 3000mah battery that you ran dead the night before, you'll see the charger start slowing down in its charge rate as it approaches the 3000mah point. If you ran the battery down half way, you'll see the charge rate start to slow down as the meter approaches 1500mah of energy input into the battery. Also, as the battery gets closer and closer to being fully charged, the amps starts to drop. It's awesome!
The manual's not totally useless because it does give some amp setting guidelines based on the specific battery chemistry. I've only had one instance where I was too aggressive with selecting too high of an amp setting, but that was my fault and I was deliberately kinda playing around with the charger to see what degree of control I have with it. That's when I connected the alligator clip connectors (you get a bunch of different types of connectors inside the box to accomodate a bunch of different battery terminal designs) onto either end of a single NiMH AA battery. I put the charger on the NiMh setting which set the correct voltage, but I put it on a pretty high amperate (maybe 3 or 4) and it wasn't too long before the charge unit caused that AA to get REALLY hot. In fact, I caused some of the external packaging to melt.
I'm not saying this to scare you away from this charger, but just to caution that the amperage setting is everything in terms of how quickly or slowly the battery recharges. Also, of course the bigger the battery the larger you can set the amperage because there's not as much internal resistance in a big battery. In the case of that single AA, I was putting way too much current through a single battery. True, I probably recharged this battery in like 10 minutes or less, but the internal resistance cause me to basically ruin the battery because of the heat was rejected since it wasn't absorbed as energy in the battery. Battery university says it won't ruin a battery to put it on repeated fast recharge cycle, but it will shorten it's life.
Anyway, it won't take you long using this charger to get a feel for what your settings need to be and like I said, the manual provides guidelines and I can also give you my own guidelines. However, the bottom line is if you're not sure, then when you put the battery on the charger, feel the battery every so often after starting to recharge. If it gets too hot then your amp setting is too high. Take the battery off and lower your amps.
All this said, you can also set the amp setting too low and it will never charge the battery. A good rule of thumb that I've found for all of the battery chemistries I've used is to start with 1A.
Oh, one more thing. FWIW, I have NiMH, Li-ion, Li-Poly, and SLA/lead/pb batteries in my battery arsenal. Although I tend to still use the stock charger on my wally world and li-poly batteries, I've used this charger on them all. I generally use this most for my NiMH and lead batteries though.
Did I mention that I love this thing?