pauluk2w

My Feedback: (7)

How long should i charge a 2700 nimh battery for? i had it on charge for about 8 hours today using a standard wall charger should that be enough to give it a full charge?

DBCherry

My Feedback: (4)

No! It will take 12 to 16 hours to fully charge a standard 600 mAH pack.

A standard wall charger puts out about 50 milli-amps. SO that 2700 milli-amp hour pack will require close to 60 hours to charge if it was drained. (There's some losses to heat.)

That's why so many of us buy "peak detection" chargers. A good one can charge that pack at 2.7 amps so that it will completely charge, at the field or at home, in about an hour.
Dennis-

pauluk2w

My Feedback: (7)

Thanks DB, I have a fast field charger but i do not trust it enough as it was one of the cheap hobbico one's, i think i will invest in a better charger as i think it will be easier than having a battery fail at the field, it will also be easier than repairing a plane after that battery dies in mid air.
Thanks paul

JoeAirPort

My Feedback: (41)

Just remember that new batteries should be slow charged the first time to make sure all cells are fully charged. If you quick charge it right away, you could loose a cell and crash. I'm pretty sure this was the cause of a crash that I read about the other day in RCU.

So use that wall charger and leave it plugged in for 2-3 days or get one that has more output, like 100-200 ma and it will charge in 24 hours or less. Whatever you do, make sure to slow charge it the first time.

And yes getting a good charger is a very good idea. Take your time looking for one and figure out just what you will be using it for (Just tx and rx? What max current will it charge at? Will you do electrics in the future?). Many new charges can do two batteries at the same time, cycle them, and charge at a slow rate or qhuick charge.

DBCherry

My Feedback: (4)

Many good "quick Peak detection" chargers allow you to set the charge rate. So you could charge the 2700 mAH pack at a C/10 slow rate (270 mAmps), which would take 12 to 16 hours. Same as a wall wart charger for smaller packs.
Dennis-

glowplug

My Feedback: (1)

Good advice from Dennis and Joe. Just a little terminology definition....you'll hear the terms, 1C, 2C, etc. "C" is the capacity of the battery, so charging it at 2.7 amps (2700milliamps), is charging it at "1C". And like Dennis said, the normal slow-charge equation is C/10. (2700/10 = 270mah) I try really hard not to charge my packs above 1C, but every once in a while, I have......just don't make a habit of it........I definitely wouldn't go over 2C with my packs.

DBCherry

My Feedback: (4)

Good info from glowplug.

While some charge their NiCD's up to 3C, I too wouldn't go above 1C. NiMH packs should not be charged over 2C, but again, I wouldn't go above 1C.
Dennis-

exeter_acres

My Feedback: (2)

Sorry to hijak... so 1C for a 600Mah OEM battery pack..... it would be OK to charge at .6 amps for quick charge instead of the .25 that is default on my Accu Cycle elite?

(I'm guessing that this would be a "field" setting... then turn it down for home charging?)

glowplug

My Feedback: (1)

exeter, yes, that is exactly correct.....charging a 600mah pack at .6 amps is charging at 1C, which is good for field charging.

mikeboyd

If your looking for a good all around charger, try the Great Planes Triton. It will do almost all chargeable batteries and cycle them up to 10 times to boot. I use two 2700's in my 33%. Charged them for many hours at .2 amps. You program the battery capacity into the charger to prevent over and under charging. On mine, I cycled them 3 times, charging at .2 amps and discharging at .3 amps. Took a week to do them both, but the last cycly was a little over 2700 for one and 2680 for the other. I can quick charge them at the field with the same charger at 1C, between flights in about 15 - 20 minutes each. Those JR 8611's like power. For packs smaller than 2000 I use a couple of smart chargers, set single switch, and forget about it until light flashes green, then go fly. NIMH's can develop a little memory, contrary to what they say, so cycling them let's you know where their capacity is. Everyone else's advice seemed rock solid. good batteris, fully charged = safer flying.