NiMh C charging rate

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slfmde

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I know how to charge Lipo but what about NiMh? So I still charge at 1C? This is for the 1:18 Ruckus with 900mah 7.2v. Charge at .9amp and full charge should be around 8.4v?

I have it set to .6amp for now to be safe. Also do larger NiMh come with a balancing port?

Thanks!
 
A 1C rate is actually a little "fast" for charging NiMh batteries! In your example above you have 1C calculated correctly. Nickle chemistry batteries have a higher internal resistance and thus heat up more during discharge and charge. So if you charge at less than 1C (.6 Amp in your example) then that's even better because you'll more fully charge the battery! A .5 C is also a good charge rate to get maximum charge into the NiMh battery and the battery will not heat up as much.

At a practical level, nickel chemistry batteries do not need to be balance charged and packs do not provide for balance charging.
 
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i_r_beej said:
A 1C rate is actually a little "fast" for charging NiMh batteries! In your example above you have 1C calculated correctly. Nickle chemistry batteries have a higher internal resistance and thus heat up more during discharge and charge. So if you charge at less than 1C (.6 Amp in your example) then that's even better because you'll more fully charge the battery! A .5 C is also a good charge rate to get maximum charge into the NiMh battery and the battery will not heat up as much.

At a practical level, nickel chemistry batteries do not need to be balance charged and packs do not provide for balance charging.
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Good stuff, but while on the topic of nimh batteries, I had read that they like to be fully charged when storing them. If they sit for more than a month I like to do a discharge/ charge cycle to wake them up. It seems to help with run times. I started using my nimh packs again in my M-05 because my lipos weren’t even using 10% of their charge on race days. They also fit better in the m-05.
 
Jeb said:
I had read that they like to be fully charged when storing them. If they sit for more than a month I like to do a discharge/ charge cycle to wake them up. It seems to help with run times.
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My own experience bears this out. I recently charged a NiMh that had been sitting for a couple of months and it didn't take a "full" charge. Another charge cycle and it was back to normal. I don't know about the storing protocol, but Nickel chemistry batteries self-discharge at a much faster rate than Lithium batteries and, over time, discharge down to their "resting voltage" (the number printed on the label... approx 7.2V in this case)

Here's some interesting info on storing Nickel chemistry batteries (from manufacturers): http://www.pmbl.co.uk/blog/how-to-store-nimh-battery-packs

The consensus seems to be that storing either full or partly charged doesn't matter like it does with a Lithium battery, but it's the storage environment that is more important. But as @Jeb mentioned, a couple of charge-discharge cycles are needed to bring the NiMh battery back to normal operating capacity.
 
i_r_beej said:
A 1C rate is actually a little "fast" for charging NiMh batteries! In your example above you have 1C calculated correctly. Nickle chemistry batteries have a higher internal resistance and thus heat up more during discharge and charge. So if you charge at less than 1C (.6 Amp in your example) then that's even better because you'll more fully charge the battery! A .5 C is also a good charge rate to get maximum charge into the NiMh battery and the battery will not heat up as much.

At a practical level, nickel chemistry batteries do not need to be balance charged and packs do not provide for balance charging.
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I.R. Beej thanks for this info. Just getting into RC (bought first truck today actually), and have been trying to find help with conversions between amperage charge rate (I have a prophet sport nimh charger 0.5-4a) and what safe charging speeds are per battery pack.
I have two batteries (so far): the 1800mah stock pack that it came with and a Venom 5000 mAh that I also purchased per my local hobby shop managers recommendation. Can you or any other RC vets help me out with proper charge speeds to prevent me from making, well, a "rookie" mistake by accidentally over-charging with too high of an amperage speed?
Sorry, this is long winded.... But I am a rookie to this awesome hobby as my name implies. I will greatly appreciate any and ALL advice I receive from you guys.
 
Okay, you've got a NiMh charger so I will presume the two battery packs are NiMh as well.

I looked up the charger and it appears that you can set it to 1A, 1.5A, 2A, 3A, and 4A. You can safely charge the 1800mAh NiMh pack at either 1.5A or 2A. I'd recommend going with 1.5A until you've got a little more knowledge and experience under your belt and you feel comfortable with your batteries. The battery will heat up a little more charging at 2 Amps but will be okay. It will probably take a little over an hour to charge at 1.5A and a little less than an hour at 2A.

Since your charger will only go up to 4 Amps, just charge the 5000mAh at 4A. It will just take a little longer (little over an hour) to charge.

Make sense?

And welcome to the hobby and the forum!
 
RookieBasher,

You said that you just got your truck, and I know that some of the new ECX's are coming with Lipo batteries now. Do you know which type you have? The advice from i_r_beej works for both types of battery, so no worries there, but if they are Lipo you will want to read up on Lipo care and storage.

Have fun with your new addiction..I mean hobby ;)
 
Nevermind, I just saw your post about it being an Amp with nimh batteries. Nice truck, enjoy it.
 
Biz73 said:
RookieBasher,

You said that you just got your truck, and I know that some of the new ECX's are coming with Lipo batteries now. Do you know which type you have? The advice from i_r_beej works for both types of battery, so no worries there, but if they are Lipo you will want to read up on Lipo care and storage.

Have fun with your new addiction..I mean hobby ;)
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@Biz73 I wish it had! But it came with a 1800 mAh nimh speedpack.
 
That's okay-- NiMh batteries are a good starter tech. They're "relatively" abuse tolerant compared to LiPos-- which is not to say you should be careless while using!
 
Did you have fun driving it? If you did, then nimh batteries aren't that bad, are they? I've been using them since day 1 and I have plenty of fun with them. That's all that counts in the end.
 
Biz73 said:
Did you have fun driving it? If you did, then nimh batteries aren't that bad, are they? I've been using them since day 1 and I have plenty of fun with them. That's all that counts in the end.
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Yeah it was great! I can't imagine really trying to sap every ounce of speed out of it...yet. At least for me, the power it has on my 5000mAh was plenty of punch for now. And then I noticed that the throttle control knob on my radio was only at 50% power..... So of course I cranked it up! I am sure that people's definition of balls out fast will vary, but dad gum that thing launched!
 
Little late on this one but I have several of the venom 5000mah batteries, and I've noticed longer run times when I charge at 1 amp vs 4. Doesn't heat up the battery either. Takes forever but if you have the time to charge at a lower rate it is well worth it. Added 25 to 30 percent to the run times
 
I will keep this in mind!
Also I have wondered this awhile but have yet to find it explicitly answered in other forum threads, but, is it okay to charge a battery fully and then not use it right away? Or do batteries need to be discharged fully and stored "empty"? (I know that with Lipo batteries, you don't drain them completely)
 
I'm no expert but from what I've read is to store these fully charged. Seen some say it doesn't matter but most say full charge. They do slowly self discharge, so would be a good idea to charge them up on a low charge rate right before you use them again.
 
Steve g said:
I'm no expert but from what I've read is to store these fully charged. Seen some say it doesn't matter but most say full charge. They do slowly self discharge, so would be a good idea to charge them up on a low charge rate right before you use them again.
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Gotcha, thank you!
 
With a nickle chemistry battery (NiCd, NiMh) it does NOT matter what charge level you store the battery. There is no benefit to storing NiMh batteries fully charged because NiMh can lose up to 10% capacity per 24 hour period due to self-discharge. Because of this, you should charge just prior to use (or as close as possible to use). It's absolutely true that NiMh self-discharge at a relatively higher rate (especially compared to LiPos) and if you store a NiMh full... you're actually wasting electricity when it self-discharges. :)
 
i_r_beej said:
With a nickle chemistry battery (NiCd, NiMh) it does NOT matter what charge level you store the battery. There is no benefit to storing NiMh batteries fully charged because NiMh can lose up to 10% capacity per 24 hour period due to self-discharge. Because of this, you should charge just prior to use (or as close as possible to use). It's absolutely true that NiMh self-discharge at a relatively higher rate (especially compared to LiPos) and if you store a NiMh full... you're actually wasting electricity when it self-discharges. :)
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@IRBeej thank you for this! I will make sure and hold off on charging until I am ready to run again.
 

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