Battery Questions Refresher.

[smashpede]

Ok I have read the battery posts lately. But still want to make sure I do things right before I try to charge My new Radio Shack Gp3300's.
1. The first charge I am going to do at 1 or 2 amps.
2. The first couple of will only last 5mins or less but should get better with more charge/discharge.
3.Do not run past point of slow down.?
4.Leave my batteries charged if not used for a while.
My one question is about trickle charging: yes or no.

The big thing is going to be tryng to figure out #3. Right now I am used to the 1500 and 1600 nicads. They run good but slow down the whole time the are run.
But you all are saying that the GP's will run good for most of the run the just slow down?
I mainly run my truck on the weekends. So should I leave my batteries fully charged during the week.
Sorry for asking the same question you all have answered all the time.Just dont want to ruin my $50 in christmas presents.

Kenny

[cooleocool]

1. Sounds fine... You can charge at 4 amps if you want though...
2. The cells will need to wake up so give them a few cycles, correct!
3. Never past the voltage drop, correct!
4. If you're storing them for more than a week or two... Charge 'em up!

Better cells will hold their voltage. They'll run strong, usually, for most of the run. Then they'll dump. You'll notice it. I leave my Ni-Mh cells charged all the time! I just repeak them when I want to use them!

[Bouncerbudz]

so you want to charge them if your going to let them sit for a week or so, and then recharge them before use?

[cooleocool]

Yes. Ni-Mh cells have self discharge properties. When they sit they discharge them selves slowly. This is why they should be stored charged. With that said, repeaking them before the run tops them back off...

[Bouncerbudz]

Thank you !!!! Answered my questions for this post . Now just need to understand the mystery of the charge LoL

[bjohnson0109]

I charged both my RS GP3300s @ 3A from the moment I got them and they were never less than 10 min ea the first run. They do get better run times as they are broken in though(15-20min). It does all depend on your truck/charger setup though.

[StampedeFamily]

Uh oh...I am new to this having just bought my "pede at Christmas. After talking to someone at LHS they said to wear the batteries down completely before re-charging. I bought the Radio Shack GP3300...played with it today and intentionally ran it down all the way. I am recharging right now at 2 amps....
How bad did I mess up?

[bumbaiboy808]

Uh oh...I am new to this having just bought my "pede at Christmas. After talking to someone at LHS they said to wear the batteries down completely before re-charging. I bought the Radio Shack GP3300...played with it today and intentionally ran it down all the way. I am recharging right now at 2 amps....
How bad did I mess up?

I think if they charge up OK, then they'll be alright. I think the thing about discharging NiMH batteries down too far is the risk of them reversing their polarity. When that happens, the cell becomes no good. Worse yet is they can explode when you charge a cell that has reversed.

Hopefully they charged OK and nothing blew up.

[bumbaiboy808]

3.Do not run past point of slow down.?

When you notice a slow down in speed, stop. You don't have to worry about slight differences in performance. When the speed is not there anymore, quit. Don't wait until the truck slows to a crawl.

[StampedeFamily]

I just finished charging...not sure if bumbaiboy was kidding...but thankfully the battery charged (finally) without blowing up !!

[71Gearhead]

I just finished charging...not sure if bumbaiboy was kidding...but thankfully the battery charged (finally) without blowing up !!

This is no joke, it's easy to wreck a pack discharging it. I will throw this explanation out there because it helped me to understand the same thing.

You have six individual battery cells in your "pack" and they are not matched for voltage or run time. This means some cells will "run out" of juice before the rest do.

When you continue to run the battery pack after it slows down significantly there is a good chance the weakest cell (the runt of the litter in your un-matched pack) will run completely out before the rest of the cells do. After that it will "reverse" polarity as the other cells pass current through it.

When you reverse a cell like that it heats up rapidly and generates gas (hydrogen I think) and lots of heat. This is called venting and there is a small hole built in the cell so it can relieve this gas and pressure without popping or exploding. If you continue to run a cell that has been reversed it will generate enough gas and heat to burn it (I did this and it stunk). I did this by running the truck down to a crawl on a low battery, although I had done it easily a couple dozen times before without problems. The battery just could not take it anymore.

If the cells in your battery pack are for some reason closely matched then when it "dumps" or discharges it will do so all at once and it will really be noticeable.

If you have one or two cells not quite like the others these cells will discharge first, giving your pack a gradual slowdown as they fight with the stronger cells. Then as more cells get to zero the pack slows down more.

So that's why people say to stop when you notice the pack dumping. By the time you actually notice the slowdown, one or two cells are getting low and you should stop discharging the pack to prevent reversing these cells and taking out the whole pack.

[tripleup05]

I have a quick question...so it is Ok to run a NiMh battery for say 5 or 6 minutes, and then recharge it? My dad used to tell me all the time with my old 9.6V Nikko stuff to never overcharge or charge them before they are used up. I know with the NiMh batteries they should never be totally used up, but is it ok to charge back up from say 3/4?

[bumbaiboy808]

I have a quick question...so it is Ok to run a NiMh battery for say 5 or 6 minutes, and then recharge it? My dad used to tell me all the time with my old 9.6V Nikko stuff to never overcharge or charge them before they are used up. I know with the NiMh batteries they should never be totally used up, but is it ok to charge back up from say 3/4?

Yes, with NiMh you can charge back up at anytime. Just make sure they're cool first. Charging warm/hot batteries decreases their lifespan significantly.

[BT_EMT]

Yes you can always "top off" a NiMH pack, no matter how much good charge is still left in it. Thus the invention of the Peak Charger, it does the thinking for you. The old Nikko may have been NiCd so in that case you would want to discharge it all the way, but not the case for NiMH's !!

Yes it's fine to run for 5 or 6 mintues and then recharge, assuming you have a peak charger, but let the pack cool off first !! Never charge a hot battery ! However after a normal, long charge, a pack will be quite warm, that is fine.

SmashPede : Some Peak Chargers like my MRC 959 will trickle charge for a while at the end of the full charge, that helps get those last few drops of juice into the pack. Trickle charging a NiMH gets a bad rep, it won't harm anything, but it will make the pack run pretty dull, won't have much punch. Most good new cells like a hard charge at 4-6 amps, that gives it the best punch. If you charge it at 1 or 2 amps, that's fine too, it just might not be as "punchy" as the hard charged one.

[BT_EMT]

71 Gearhead, that was a nice tutorial !! You make a good case for paying extra for an economy matched pack. You get the benefit of having your pack pretested at the matcher and would be highly unlikely to get a wimpy cell reversing as you described.

Disclaimer : I advocate buying the least expensive matched packs (Economy, Club Grade etc.) for bashers, NOT the $70+ Race/Team level packs. I also agree most people will be happy with their cheap sport packs for a while. I say get one cheapo and one matched, and decide for yourself instead of listening to the endless "battery wars" debates.... LOL And if you upgrade to a hot motor or a brushless system, then a side by side pack with 12-14ga wire and Deans or PowerPoles becomes very important.

[cooleocool]

I don't see why one couldn't recharge a Ni-Cd cell with some juice left in it. The main reason is the fact that he didn't have a peak charger. If you have a peak charger, you should be all set...

Matched packs are probably a good idea, but I'll probably stick with my Offshore packs. At least that's what it's looking like for now... I suppose it could change. Steve uses virgin, untouched, matched, picked though cells. Not matched, but they're fine for me I suppose. His quality battery building makes up for any downside in my book! Plus, I can get them in soldered stick packs, though I may start making my own packs, in which case, I'll build side-by-sides. I'd get Steve's zapped cells too if I bought them loose.

[BT_EMT]

Yeah if I need a stick form pack, I'd order from them too, I have not seen anyone else claim to solder stick packs. If anything the customers he sells to in the super high power brushless boat world REALLY need quality construction. I love that vid clip of the brushless boat hitting over 100mph, on the ol GP3300's. Prob only gets about 60 seconds run time or less.

[smashpede]

I only got to run each pack once but I got at least ten minutes min. with each pack. This is only the first run. And they make my XL-5/titan faster.

Will try to run them again this weekend.
Kenny

[jaofos]

Yet another reason I love my A123's.

Cool schmool, after a full dump or full charge and even 10 back to back cycles they stay nice and cool, maybe slightly warm at the most.

Peak schmeak! Fully charged stays fully charged for weeks! I can fully charge it, let it sit for 2 days then run it and it's got the same power as if it just came off the charger!

But again, these cells aren't for everybody yet.. maybe in a few years they'll become as popular as Nimh's

[BT_EMT]

I'd like to see A123 use an AC/DC charger instead, I have no desire for a DC charger only. I'd like to get into them also, but the shapes of the packs just aren't for the bulk of the market. They do seem ideal for an FLM chasis and a Mamba system running the 3s battery ! But they say they are working on new shapes and sizes, maybe in a few years they will be more mainstream for RC cars.

[jaofos]

I'm currently looking at changing my packs over to a side-by-side configuration instead of pyramid configuration. The A123 guy says it would be "difficult" but that's far from "impossible".

Also, from what I've seen.. most good high end chargers are DC only..