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How to I find out or calculate what rate to charge batteries?

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How to I find out or calculate what rate to charge batteries?

Old 05-06-2007, 06:08 PM
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RevToTheRedline
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Default How to I find out or calculate what rate to charge batteries?

I'm probably gonna pick up an Electrifly Triton Jr for my RX and TX packs. But I don't know how to figure out what rates to charge them.


For example a 2000mAH 5 C cell NiCad pack, how many amps would you charge that? Or a 1400mAH 5 cell 2/3A NiMH pack. Is there a math formula to figure this out? The charger does 0.1A to 5A in 0.1A increments. What about discharging NiCad packs? The Triton Jr only does up to 1A discharge, doesn't seem like much.
Old 05-06-2007, 06:35 PM
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Default RE: How to I find out or calculate what rate to charge batteries?

it all depends on how fast you want to charge them. For the smaller packs, they will heat up a bunch when you charge them too quickly, but basically you want to keep them around 100F or less, but they can go up to about 120F. The lower the temp when charging, the better it is on your pack.

If you have the time, do a c/10 charge. To do that you're gona take your capacity, so lets go with the first pack, and then divide it by the 10 hours. That would give you 200mA or 0.2A charge rate. Leave that on for 12 to 14 hours to allow for the differences between cell charge rates. Your triton jr should figure all that out though. I don't think it lets you adjust your delta peak, so just plug in 200mAh or 0.2A and let it go till it says it's done =)

If you want it done in just over 5 hours, then just take the capacity and divide it by 5.

as far as the discharge, any of those packs can take a 1A discharge =)
Old 05-06-2007, 07:02 PM
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Default RE: How to I find out or calculate what rate to charge batteries?

That's all good info, unfortunately the silly T-J has a 1.5 hr timeout feature so a rate needs to be selected that will deliver the required capacity in 1.5 hrs or less. Or a restart could give you 3 hrs, and so on .
Old 05-06-2007, 07:09 PM
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Default RE: How to I find out or calculate what rate to charge batteries?

No kidding? I thought it was a computer charger that automatically shuts off accordingly. Is it just a charger with a timer and selectable charging amp rate?
Old 05-06-2007, 07:13 PM
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Default RE: How to I find out or calculate what rate to charge batteries?

It is a "peak" or automatic charger that shuts off automatically when battery is full, but it has the silly "safety timer" set at an unchangeable 1.5 hrs. So in effect anything under a 1.5 hr charger will terminate automatically. If attempting to do a slower charge than that then a restart will be in order. Bummer. [:@]
Old 05-06-2007, 07:15 PM
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Default RE: How to I find out or calculate what rate to charge batteries?

Wow thats silly. Does the near identical Multiplex LN-5014 have the same "problem"?

I guess the T-J is not as advanced as I need. But I don't want to get up in the ICE level of charging ability, that's just too much for my needs.
Old 05-06-2007, 07:26 PM
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Default RE: How to I find out or calculate what rate to charge batteries?

I might just get an MRC Super Brain 977, since I won't be carrying around the 10A power supply to the track, it's actually pretty small, and it can charge 2 packs at once, very nice, ~$95 isn't bad either.
Old 05-06-2007, 10:43 PM
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Default RE: How to I find out or calculate what rate to charge batteries?

I just read over the Multiplex manual and the safety timer isn't mentioned. I'm not familiar with it, but I do know there are a ton of chargers in that class (50-63 watts) (14 cells and 5 amps).

The 977 is good charger , but unfortunately doesn't like varying the charge rate much away from a 1C rate (1 hr charge) It can go a lot faster, but when trying to go slower sometimes causes an error of "slow peak" It would not be a good choice for radio batts.

It sounds like you don't need to charge stuff real fast so the Hobbico Accucycle Elite or MKII might do the trick for you. They are both dual chargers.
Old 05-07-2007, 12:24 AM
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Default RE: How to I find out or calculate what rate to charge batteries?

I was about to ask about those two Hobbico chargers, they look super sweet. The Elite especially.
Old 05-07-2007, 02:52 AM
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Default RE: How to I find out or calculate what rate to charge batteries?


ORIGINAL: guver

That's all good info, unfortunately the silly T-J has a 1.5 hr timeout feature so a rate needs to be selected that will deliver the required capacity in 1.5 hrs or less. Or a restart could give you 3 hrs, and so on .
wow, that's the pits. I didn't know about that =( I would stay away from that thing then.

You might also look at the triton 2 or the ice
http://www.rcuniverse.com/forum/fb.asp?m=5815673

the thing with those would be that you can only charge one at a time, just like with the triton jr.

thanks guver for the good info =)
Old 05-08-2007, 08:52 PM
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Default RE: How to I find out or calculate what rate to charge batteries?

I have the MRC 977 and use it at C/2 on my radio batteries, it doesn't false peak. I use it on both the 4 cell NiCd 700mah packs and the 600mah 8 cell NiCd Tx packs set to 0.3 amps charge. They only get slightly warm at the end of the charge cycle. I also use it on 1000mah NiMH set to 0.5 to 0.7 amp charge. Still no false peaks.

I fly so up until recently my needs for a charger were a lot different than for cars. Flying nitro, both Tx and Rx packs are AA size cells and prefer slow charge. With cars and Flying electrics, you get into sub-C cells or larger that are designed for faster charge times. Cars and electric planes are both getting into LiPo packs. Their chemistry is different, and so are the charge algorithms so they require a charger set up for them.

The 977 will charge NiCd, NiMH, LiIon, LiPo, and Lead Acid and Lead gell. The only thing I don't like about it is that the B port has a tamiya connector on it. I would have been happier if both ports had banana plugs on them.

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