Charging\Discharging Practices

[godale03]

Hey Guys,

I have a few questions on how to properly charge\discharge my batteries.
I have 3600, 4200, 4600, and a couple of the Reedy R-14 which I think are 1200. All NiMh

I have a MRC Super Brain 989 and I just ordered a Team Checkpoint charger.

First question is how many amps should I charge each pack safely?
I have no idea of what cutoff voltage I need to set, temp cutoffs, or anything about the peak voltage and all of that stuff. Basically... I have no idea how to set up and make use of the chargers features. LOL

Second question is how to properly discharge them?

- I do not want to use my chargers to discharge, because I have heard that is not good for the chargers.
- I have mostly stick packs (Shotgun style) with deans connectors
- I have a few saddle packs and a few 6 cells (side by side) that use the battery bars and do not have the shrink tubing.

I do not own any type of discharger other than my chargers. When it comes to properly discharging batteries I am pretty much clueless as to how to do it properly. I have also heard of "balancers". Is this the same as discharging? I hope I have provided enough info, but can provide more if needed. I have read to many threads of exploding cells and would like to avoid this. I am also tired of not knowing exactly what I am doing when it comes to battery care and have spent to much money to let those packs die. I don't have alot of cash to spend but if I have no choice at least I can start saving now. Thanks in advance.

Tom

 

[robmob]

General rule of thumb is that a pack can be charged at 1C which means the 3600 would be 3.6 amps and the 4200 would be 4.2 amps etc.

Using your packs as an example, I would charge them at the following rates the night before racing:

3600 = 3 amps
4200 = 3.5 amps
4600 = 4 amps
1200 = 1 amp (I never charge small packs above 1 amp because they get to hot)

Right before the main, I would force feed my 4200 matched pack at 6amps so I can get a little extra burst off the line.

I use a Deans Battery Bar to discharge my packs the night before I am going to charge them for racing. That way I can be assured they are cool and relaxed before taking the charge.

A balancer will only work on side by side race packs since it brings all the cells down to the same voltage before charging. I use a Tekin Battery Doctor and I do it right after I use the battery bar. I you are using standard end to end stick packs, you can't balance them.

Of course now I use lipos now so all that pain above has gone away.

 

[godale03]

First off thank you....for the info.

I have not been able to find a deans bar for sale any where, and my LHS said that they are not available any more. And only my pro packs are capable of being balanced correct? I will have to look at the Tekin battery doctor... I am assuming it is pretty expensive though.

I am not quite ready to go lipo yet because they seem to be to voltile, and very sensitive.... at least from what I understand anyway.

I am just tired of not knowing how to use the equipment I own. The books that come with this stuff are no help at all, and if you don't understand the lingo... the web is not much help either.


How do you set your temps, and times, and cutoff voltages? That stuff is what is really confusing me now... well at least the most anyway. LOL

Tom

 

[robmob]

Here is the equalizer I use.

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXKYP6&P=7


I ended up buying my battery bar on ebay awhile back for about $12. I felt like I stole it from the seller. LMAO


On my Checkpoint, I will choose the batt type, set the mah capacity and amp charge rate. That is it. I let the charger do the rest and I don’t use a temp probe. If I did, the Checkpoint has a preset for that as well. I think it is around 120 degrees, but I am not sure.

 

[alpinehyperlite]

I am not quite ready to go lipo yet because they seem to be to voltile, and very sensitive.... at least from what I understand anyway.

If you look at the last two "battery problems" aka explosions, from earlier this week on this site, (charlestheman, and abadk9420) both blew nimh batteries. I havent found one problem on here with lipos poppin. I had one get bitten by a snake and it punctured almost all the way through, and still didnt have it pop. Didnt use it again, damn cursed battery. Lipo's arent as dangerous that i have found, that people are talking about.
https://www.rcnitrotalk.com/forum/showthread.php?t=60730
https://www.rcnitrotalk.com/forum/showthread.php?t=60767

 

[abadk9420]

With the new team check point charger you are getting if you read the directions it tells you how to set it up, as a general rule of thumb when I use my charger to discharge I discharge them at twice the rate I charge them at, so if you charge say your 4200 pack at 4.2 amps I would discharge it at 8.4 amps with a voltage cut off of 0.9 volts per cell or 5.4 volts for a 6 cell pack. and I would not be overly concerned about your batteries blowing up both mine and charles packs were rare cases, my pack had a bad cell that I didn't catch and charles had an old charger that did not cut off when it was supposed to but if you monitor your packs when charging and check all your batteries regularly you should not have any problems with any type of battery charging, and considering that was the first battery that I have had that happen to in 25 + years of running electric rc's and did not blow while I was charging it but rather when I was driving it I don't think you have to much to worry about...

 

[ohmygahitscoby]

Tamiya has a discharger on sale right now for only $7. I received mine yesterday. I haven't tried it yet though, I still need to put some deans on them.
http://www.tamiyausa.com/product/item.php?product-id=55058

They don't have a picture, but this is the one:

 

[abadk9420]

Tamiya has a discharger on sale right now for only $7. I received mine yesterday. I haven't tried it yet though, I still need to put some deans on them.
http://www.tamiyausa.com/product/item.php?product-id=55058

They don't have a picture, but this is the one:

Just make sure if you were to get this discharger to only use it on 6 cell packs or it will probably over discharge the battery.

 

[godale03]

Thanks alot for the info guys. I am just so tired of not knowing exactly how to use my equipemnt to properly care for my batteries. I know it is my responsibilty to learn... I am not expecting to learn this all by osmosis. I am very lucky on the other hand to have you guys and gals out there in RCNT land to point me in the right direction. Properly maintaining your electric stuff is almost an exact science and can be very technical. That is what I love and hate about this hobby sometimes... You know sometimes I would just love to just plug it in and forget about it... other times.... if I have the time! LOL, I love getting technical with it all. I am sure the other fathers out there understand, and I am sure I have said it a few thousand times over the last few months, but getting used to having a baby around the house is a HUGE adjustment, and as much as I love my daughter... she is a 4 month old dictator! My RC's have suffered, and so has the time I have to spend doing the little things, like caring for my packs, and general maintenance on my rigs.

A buddy of mine gave me a Novak discharger a few weeks back, but to be completely honest with you didn't know what I had until I looked at what Robmob had posted. It came with a few battery packs I bought from him a few weeks ago. I feel pretty stupid about it now.... I mean not knowing about it. I will take a few pics to let you guys see what it is and if it will work for me. Thanks again guys.

Tom

 

[Lessen]

The one thing that has struck me about this thread is that you mentioned that you've heard that using a charger to discharge is not good for it? I've never heard this. Did you pick that info up here?

 

[godale03]

Hey Lessen,

I am sure I have heard it here before... from who, I can't recall. Most recently though, it was from my LHS. I was told that using your charger to discharge creates alot of heat that will shorten the life of the charger. Is this true or false? I don't know. I was hoping to find out for sure from you guys here on the forum.