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Battery charge question

Battery charge question

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Old 03-02-2012, 09:09 PM
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Default Battery charge question

Hey guys,

I am new to the RC world and am wondering about battery charging. One of my batteries has on it the amp rating recommended to charge it, but the other is missing.

I heard that stick with 1c is a safe bet. I have a 5000 mAh battery and a charge that can charge up to 5 amps, so I can do 1c on that battery, so question #1, is 5 amps safe to charge that battery with?

Question #2 for my lower rated battery (3300 mAh) what is best to charge at. 0.5c, 1c, or 1.5c?

I looked it up online and have found answers varying from "always just charge with 5 amps" to "never charge more than c/2" so I am confused by the topic. :P

Thanks guys!
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Old 03-02-2012, 11:17 PM
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Depends on the type of battery they are, the 1C guideline only applies to lipos. Nimh and nicads are different, 1C doesn’t apply.

If they are lipos then 5 amps for the 5000mAh, 3.3 amps for the 3300mAh and so on.

If they are nimh it depends some on the exact cells and how they are being used, but 4 amps is probably a reasonable starting point. Adjust depending on how warm they get during the bulk of the charge, reduce some if they get more than slightly warm except at the end when they should noticeably warm up. But not get so hot that they are uncomfortable to hold.
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Old 03-03-2012, 08:13 AM
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Originally Posted by Dave H View Post
...the 1C guideline only applies to lipos.
There are plenty of LiPOs on the market that allow 2-10C charge rates. The latest Hyperions are 5C, as are the latest Gens Ace.

Your batts, so you make the call, but if the manufacturer says it's OK there shouldn't be an issue. I charge my GA 5300 mAh packs at 20A when I want them done fast (<20 minutes!) and they don't even get warm.
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Old 03-03-2012, 08:36 AM
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Originally Posted by porterdog View Post
There are plenty of LiPOs on the market that allow 2-10C charge rates. The latest Hyperions are 5C, as are the latest Gens Ace.

Your batts, so you make the call, but if the manufacturer says it's OK there shouldn't be an issue. I charge my GA 5300 mAh packs at 20A when I want them done fast (<20 minutes!) and they don't even get warm.
Thus the word guideline, especially since he doesn't appear to have information that his batteries are rated for high charge rates. He was asking what is safe. 1C is safe for a lipo, 10C may or may not be.

What I really meant is all that, especially 2-10C, does not apply to nimh in case that is what the original poster has, since he didn't appear to mention which type of battery. And since 3300 was a popular nimh size...just a speculation on my part.
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Old 03-03-2012, 02:26 PM
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Sorry for forgetting to mention the battery type. They are Nimh batteries.

I have a 3000 and a 5000 mAh. My charger only goes up to 5a, so I did 5 on my 5000 mAh battery but it looks like it only peaked at around 4.2, but it finished charging in about an hour or so; so I'm happy.

The 3000 battery charges in about the same amount of time at 3amps so I think it is safe to keep it there since I am not in a rush.
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Old 03-03-2012, 05:11 PM
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Sounds reasonable.

In general with nimh higher charge rates will provide a little more punch, a little less run time. Just watch the heat, keep them below 125F or so.

Lower charge rate will increase run time slightly, and is a little easier on the batteries. Donít go way low though, or the peak detection function of the charger wonít work properly, wonít shut off automatically. Usually anything below say around C/5 risks being an issue for proper peak detection.

Some will recommend a C/10 forming charge when new or after sitting for a while, mostly for transmitter & receiver batteries in my opinion, that needs to be controlled by time, usually 14~16 hours.

Oh, and welcome to the hobby, enjoy!
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Old 03-04-2012, 04:07 PM
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Originally Posted by Dave H View Post
Sounds reasonable.

In general with nimh higher charge rates will provide a little more punch, a little less run time. Just watch the heat, keep them below 125F or so.

Lower charge rate will increase run time slightly, and is a little easier on the batteries. Donít go way low though, or the peak detection function of the charger wonít work properly, wonít shut off automatically. Usually anything below say around C/5 risks being an issue for proper peak detection.

Some will recommend a C/10 forming charge when new or after sitting for a while, mostly for transmitter & receiver batteries in my opinion, that needs to be controlled by time, usually 14~16 hours.

Oh, and welcome to the hobby, enjoy!
Definatly... the slower you generally charge them, seems to give a little more run time and power vs a fast charge.I never charge nimh more than 2amps.
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Old 03-05-2012, 06:28 AM
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Hmm, good advice. My charger does 0.8, 1.5, 3, and 5 amps. I think I will try charging the 5000 batteries at 3 amps next time and see how long it takes to charge and discharge.

Yesterday my wife and I ran a good 45 minutes ish on a single 5000 mAh battery charged at ~5 amps.
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Old 03-05-2012, 09:50 PM
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Another, mostly related, question.

What do I do if I have a charged batter, and for whatever reason don't use it?
  • put it back on the charger for a "trickle charge" if I'm going to use it the next day
  • Leave it off the charger but...
    • Top it off on the charger right before I use it next
    • Just use it until it is drained before charging again

I have done this 2 days in a row now. Yesterday I used most of a 3000 mAh battery, and didn't touch another 3000 mAh battery (We have 2 cars).

Then today I charged up the 5000 mAh batteries but after finishing off the remaining 3000 mAh batteries it was too late to go in.

So now I have 2 fully charged 5,000 mAh batteries that I *should* be able to use tomorrow, if not then Thursday.
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Old 03-06-2012, 01:36 PM
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Originally Posted by Final Asgard View Post
Another, mostly related, question.

What do I do if I have a charged batter, and for whatever reason don't use it?
  • put it back on the charger for a "trickle charge" if I'm going to use it the next day
  • Leave it off the charger but...
    • Top it off on the charger right before I use it next
    • Just use it until it is drained before charging again

I have done this 2 days in a row now. Yesterday I used most of a 3000 mAh battery, and didn't touch another 3000 mAh battery (We have 2 cars).

Then today I charged up the 5000 mAh batteries but after finishing off the remaining 3000 mAh batteries it was too late to go in.

So now I have 2 fully charged 5,000 mAh batteries that I *should* be able to use tomorrow, if not then Thursday.
Anybody have an answer/suggestion for this or do I need to ask it in a new thread?

Thanks!
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Old 03-06-2012, 10:21 PM
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Originally Posted by Final Asgard View Post
Anybody have an answer/suggestion for this or do I need to ask it in a new thread?

Thanks!
For general use, ie not ultimate race care, just recharge them before use. Use the same charge rate, referred to as a repeak. Should only take ~5-10 minutes or so.

You could just run them as is, but they will have a little less punch and capacity. Nimh self discharge some while sitting charged.

Oh, and for storage keep some charge in them, to prevent self discharging to dead essentially. Long term storage they need a little charge every couple weeks or so, to prolong life.
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Old 03-07-2012, 04:41 AM
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Alright, thanks. Good to know for next time.

I ended up using them as is, and it had noticeably less run time and slightly lower top speed.

Next time I will throw them back on the charger. It should be smart enough to not over charge them. )

Thanks!
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