New NIMH

[mattman683]

I just got new batteries for my 30% AW extra. 2 2700 ma nimh from Radical RC. And a 2150 on ignition. I am charging with the spektrum wall warts, they charge at 110 mah. Is there some sort of break in process I should follow? Do you have some sort of algorthim that will tell you how long you should charge? Thanks!

[dick hanson]

You can't really screw anything up using the warts - aprox 24 hours and 30 hours (1/10) hours.
On my first DX7 I would leave it on for days at a time as it was a 65 ma charger and the tx batts really worked well
just avoid any peak type charger for first few cycles - At least that's what I found to be the best approach.

[MikeC3D]

What the hell is a nimh battery???????

[Flyfalcons]

What the hell is a slow charger?

[dick hanson]

Don't worry, the NiMh properly broken in, for the application noted ,will be just fine
My own stuff is all A123 /VPX - Ihve full support equipment for them and it cost a few hundred bucks but I also use these cells for power on electric motor models
A wall wart and Nimh are slow to charge but the results are still very good .

[mattman683]

Do you guys know of a algothim or formula for charging times?

[dick hanson]

simple is still best - charge at under 1/10 ratings and then figure time required to match total battery rating
example
1000 ma battery
charge at 100 ma
for 10 hrs
OR 5 ma for 20 hrs -etc..
Cincinnati?
I used to work in that town
I was a blacksmith in a bakery

[mattman683]

What bakery? A blacksmith?

[dick hanson]

I ferget the bakery name
but I used to shoe the flies ----

[mattman683]

Busken?

[CamLight]

I agree, charging at 1/10C for 10 hours is good for everyday use. But I also recommend a 125% charge every month or two followed by a complete discharge down to 0.9V-1.0V/cell.

As a pack is used, small differences in the cells become result in larger and larger cell-voltage differences over time, resulting in the pack's cells becoming unbalanced. That is, the cell voltages are all different. This itself is not a problem. But when discharging it can result in the cutoff voltage of the pack being reached before all of the cells have discharged. With badly unbalanced packs, a cell could even reach zero volts before the other cells have dropped enough in voltage for the cutoff voltage to be reached (and the discharge stopped). If that zero-volt cell is still discharged (once dropping to zero) it can become damaged.

An occasional long, slow "overcharge" gives every cell a chance to become fully charged while not overheating the already-charged cells. This helps to balance the cells in a pack and lengthen the pack's life. The occasional complete discharge (and subsequent charge) helps to break up the cell's crystalline structure, conditioning the pack and lowering its internal resistance (helping to prevent voltage depression under load) thus increasing its capacity.

[Aerobat]

Here's a handy battery charge time calculator I put together. This is for NiCD and NiMH. Just plug in the capacity and charge rate and it gives you the hours needed from full discharge to full charge.

I also use a Sirius tester which brings the batt down to full discharge and tells you how many amps it had in it.

Edit -- Hmmm...it says .xls is an invalid file format. If we can't post files like this just PM me with your email address.

[Slats!]

Kinda a dumb question, new to this but do you just leave the batteries on to discharge or do you have another way. Its winter cant fly to run them down, should you also cycle them on the first charge. I have a spektrum radio and I am reading people are charging them for 30 hours, seems excessive.

[Slats!]

Also do people usually use better chargers than what comes with the standard equipment.

[blackbeer]

New NiMh's or NiCad's need to be cycled 3 or 4 times before they can reach their full capacity. If you don't have a charger that will cycle a battery, that is, charge and discharge at a set rate then I would suggest getting one, or at least get one of those little discharge things, I forget what they are called.
A good charger, IMO, is not an item one can have or not have, it is a must.....................

Tom