NiMH batteries info and charging Do's and Don'ts

[themissingelf]

Many thanks. I will give it a go!

[themissingelf]

I think the battery may be gone... Cycled three times, using a bulb to drain slowly, but in the car it's just the same even though it's putting out putting out 7.2v.

Sent from my ONEPLUS A3003 using Tapatalk

[Fly In My Soup]

5 hours ago, themissingelf said:

I think the battery may be gone... Cycled three times, using a bulb to drain slowly, but in the car it's just the same even though it's putting out putting out 7.2v.

Sent from my ONEPLUS A3003 using Tapatalk
 

 

Try ten times!

 

Charge Up to 8.2v at 0.5a- then down to 6.2 with a bulb/fan etc etc

 

Repeat 10 times, if no improvement its probably rodgered

[Mark_C]

Another question about conditioning new batteries, I've got hold of a charger that can be put in a charge/discharge cycle. On the discharge its possible to set a discharge amps and voltage. On first read I thought this was a rate but now I'm not so sure, the manual (https://www.overlander.co.uk/media/downloads/VSR_Manual_V3.pdf bottom of page 12) suggests the voltage is a "final" voltage. From a bit of reading 0.8v per cell is the lowest you should go to, so I was going to go for 1.0v, thus the setting would be 6v ?

Edited May 31, 2018 by Mark_C

[Fly In My Soup]

If cycling a 7.2v NiMH battery, I would only go down to 6v absolute minimum, preferably 6.2v.

 

NiMH batteries do not react well to being over discharged!

 

Looking at the manual, I see section 7.3 has some good NiMH cycling tips

 

You'll be able to view how much the capacity, and thus performance, of the battery will increase with very cycle

 

[themissingelf]

Just wondering... Would a voltmeter be suitable for discharging (i.e. leaving it connected)? It would make it easy to see what the voltage is, stopping it over-discharging.

[Fly In My Soup]

3 hours ago, themissingelf said:

Just wondering... Would a voltmeter be suitable for discharging (i.e. leaving it connected)? It would make it easy to see what the voltage is, stopping it over-discharging.

 

I wouldn't know!

 

I would assume it doesn't draw enough A, and also i wouldn't know of the draw from a voltmeter is consistent across the discharge cycle.

 

Check what the Amp draw is, you're aiming for 0.5-0.6 Amp draw down to 6-6.2 volts On a discharge cycle.

 

Ive used small ESC fans in the past as they usually draw a consistent 0.5A access the entire cycle.

[Outlaw]

I found this and thought great, an idiots guide to batteries. 

 

It didnt take long for em to get confused though.  

 

Its nice that there is such info on here, especially for noobs like me, top marks FIMS. ?

 

Just one question,

 

you say

 

• Storing standard NiMH cell packs (short term - under 8 weeks)

If you plan to store your standard NiMH cells simply until the next weekends bash, then it couldn't be simpler, just ensure your batteries are roughly 60-% charged at time of storage and simply charge as usual the next time you use them.

 

Does this mean that once my nimh gets to approx 60% I should stop charging, then charge fully just before I use it? 

Or

Dont let the battery get lower than 60% when in the car, this seems unlikely, but I would just like it clarified, I don't want to go and bugger my new battery through ignorance. 

 

So far, with my 8.4v 3000mah battery Ive charged it 3 times, each time to its full capacity, Ive then used it the next day, im guessing that's ok. But now I won't be using it till next weekend, so should I do the 60% charge thing until then? 

 

Confused from Kent. ?

[Fly In My Soup]

29 minutes ago, Outlaw said:

I found this and thought great, an idiots guide to batteries. 

 

It didnt take long for em to get confused though.  

 

Its nice that there is such info on here, especially for noobs like me, top marks FIMS. ?

 

Just one question,

 

you say

 

• Storing standard NiMH cell packs (short term - under 8 weeks)

If you plan to store your standard NiMH cells simply until the next weekends bash, then it couldn't be simpler, just ensure your batteries are roughly 60-% charged at time of storage and simply charge as usual the next time you use them.

 

Does this mean that once my nimh gets to approx 60% I should stop charging, then charge fully just before I use it? 

Or

Dont let the battery get lower than 60% when in the car, this seems unlikely, but I would just like it clarified, I don't want to go and bugger my new battery through ignorance. 

 

So far, with my 8.4v 3000mah battery Ive charged it 3 times, each time to its full capacity, Ive then used it the next day, im guessing that's ok. But now I won't be using it till next weekend, so should I do the 60% charge thing until then? 

 

Confused from Kent. ?

 

Thanks Kent.

 

Think of the above like a set of good practice rules.....

 

If your storing for a week...then I wouldn't worry too much about going down to 60%.....

 

Anything longer than 2 weeks would justify going down to 60%...

 

In general...NiMH batteries are quite resilient....the 'rules' can be bent..unlike lipo ....where storage voltage is critical to longevity

 

P.s if your confused about how to get down to 60% voltage....just run your car until the ESC cuts the throttle and brake due to low voltage....take home and charge for 10 minutes only...this will get you in the rough ballpark of 60%

[Outlaw]

Ah, the audio (oba model) is the first thing to go, then very shortly after the power goes, in future as soon as the audio goes I'll call it a day and turn it off.

Luckily my charger does give some indication to the battery condition through out charging. 

 

Anout 10 minutes you say. 

 

Thanks FIMS. ??

[TrinityUTT]

Can someone help a noob

I bought a the following batteries and charger.

Question 1. Theres a plastic wrap film around the batteries, do I leave it or take it off?

Question 2. Which setting do I charge them on? 1,2 or 4?

If i understand the instructions, its 4A for 45mins


Thanks for the help.

[ChrisT]

4amp will charge it quickly, 2amp would be ideal iff you're not in a hurry.

 

Leave the plastic wrap film on, it's heat shrink that holds it together.

[TrinityUTT]

4amp will charge it quickly, 2amp would be ideal iff you're not in a hurry.
 
Leave the plastic wrap film on, it's heat shrink that holds it together. [emoji106]

I'd rather charge safely.

Perfect thanks.

Not in a hurry, have been building the kit and still a bit to do yet.

Thanks again

[ChrisT]

18 minutes ago, TrinityUTT said:

I'd rather charge safely.
 

 

I also prefer to charge that way. I only run NiMH myself so I tend to charge at half the C rating. C rating is the mah of the battery. In your case the C rating is 3000 so half that would be 1.5 amps. As your charger doesn't have a variable charge rate, 2 amps would be my choice. Perfectly fine.