Noob question (kind of)
 

I have been charging lipo for a little while now and just picked up the ICharger 208B. When I go to charge, I has a selector for amps. I have read a couple of different things, but can someone please clarify for me. I am thinking that Amps=capacity (i.e. 5.0amps=5000mAh). Or can I charge a 4S 5000mAh pack at 10amps? Can someone please clarify before I burn my house up? Thanks.

What you have defined is the 'C rating' of the battery. You are correct - this is the recommended method of determining an appropriate charge amperage.

Your Lipo packs should be charged at 1C, (5 amps) regardless of how many cells unless it specifies on the pack that it can be charged at a higher rate.

The 'C' for charging is simply capacity (mah)/1000. It should say on the label on your lipo if it is capable of more than 1C charging. If it doesn't say, only safe thing is to do is charge at 1C. Since this is a potential liability issue, manufacturures are pretty good about having it on their label.

So basically, just so I am straight...1C=5 amps. Now, my batteries are Turnigy 4S 5000mah, they say that they can be charged at 2C. Just so I am correct, they can be charged at 2C=10 amps. Am I correct on this one?

Also, when charging multiple batteries in parallel, how do I adjust the amps on that? Do I do 1C per battery or 1C overall? I know and have seen it done with this charger, just want to be sure before hand. Thanks again guys.

You're correct, 2C would be 10amps. The 208B is set up to charge in series, not parallel - this is quoted from AMain's ad for the 208B -

"This charger is also designed to allow you to balance multiple batteries at once as you can charge and balance up to two 4S batteries, two 3S batteries or three 2S batteries at once. When you connect multiple batteries, the batteries also need to be connected together with a serial charge lead. You should also make sure all the batteries are discharged or used in the same groups that you charge them in (ie: two 4S batteries used in series for a 8S battery pack etc)."


You would set the charger to charge at the amps needed for the equiv lipo with them wired in series, Say you series connected two 3S 5000mah lipos - that's a 6S equiv and the 1C charge rate is 5amps, 2C would be 10a. But you would set cell count for 6S.

Remember in series, voltage adds, capacity (mah) stays the same.

I read that under the Amain description. There is another forum (rcgroups I believe) that they are using it to charge in parallel and charging mulitple batteries at once. There is also a youtube video that shows the guy charging 6 3S lipos all different capacities at once. I am at work and don't have the links on me. Otherwise I would post them. Thanks for your help though. I appreciate you confirming that for me.:nod:

Does charging a 2C battery at 10 amps shorten the life of the battery? Also is there any benefit to charging at a higher amperage other than speed of the charge?

I've seen the utube. The prob is balancing - I didn't watch all of it but I'm guessing he doesn't show you how to build the special parallel balance harness he was using at the start. You have to know what you're doing to make one - you can short the lipos thru the balance connectors, I've seen pics where that happened on RCM. Even when the balance wires pop, saving you from a total melt-down cause they can't take the current, you've still got a mess to fix.

Hope they show enough detail on RCGroups.

If the lipo label says 1C, charging at 2C+ may shorten life, especially if the lipo gets warm while charging at the higher rate. If the label says 2C or 5C, there may be a little life lost, but its going to be a small percentage, or at least if its a Hyperion lipo (less than 1%).

Some of the lipo manufacturers are now saying that their 1C rated lipos have been 2C all along, so it may not be a huge deal anyway. Still I tend to play it safe with lipo and honor the label's advice.

No, the only reason for higher C charging is to cut charge time.

Ok Thanks. A fellow at the local hobby shop was saying that if you charge at a higher amp that somehow the battery would have more punch. I was kinda skeptical of this theory but didnt know.

That was/is true for the old style NiCD batteries but not for LiPo.

OK. Thanks for clearing it up for me.

It may have been for NiCds, but was really a NiMh practice that racers used. It has no bearing on lipos though - there is no increase in punch. If its cold where you're running, you can improve lipo performance by warming them up. Lipo performs better when they're warm. Plane guys know this, been doing it for a long time - they pre-warm them up to about 100F (body temp).