Chris_RC

They have a beginner class. I seen a guy with a 3s lipo/mamba max 5700 in it. He wasnt the best driver for sure but he was having a great time.

Access

I hear that is a really good track too, people where I live who don't race at our so-so local tracks are driving for 2-3 hours north to race there.

TheTruckingGuru

What is OCRC any link to this track? Sounds worth a visit. There is a good one in Riverside as well. I think with the fuel cost no one wants to drive to far to bash or race. Anyway maintaining NIMH can be a $5%@#$! If not used on a regular basis. Otherwise I have to to cycle them a few times to bring them back to life. It takes a long time. A 3800 NIMH could take a full day to cycle. Not that you do much work with it. Just charge slowly until it stops, then discharge, then charge.........Sometimes it takes another cycle. Then you run it until the car is nearly drained, then after it's cool it takes a full charge. It really only needs cycling if you don't run the battery down or have had them stored for a while. I store them fully charged in the fridge. As for brushed and brushless I don't run my brushless bashers any faster then someone with a brushed motor. Helps to keep my cars in one piece.

73

I'm only a few months into this hobby and although I've so far learn a little about Nimh batteries, it's till quite confusing as to what is best to do, if I do not have a balancer.

Does charging these batteries at lower Amp improve their lifespan? Had recently bought another Team Orion 4500, so is hoping to keep it good for as long as possible without using a balancer.

I use my batteries about 3 times a week each, and never charge them over 3.5 Amps. The 3700 are only taking in approx 2300 now, while the 3300 are peaking at 2100. Is it normal that they lose capacity over time, os am I charging them below optimum Amphere?
Also, is there anything I can do with the battery resistance thing? The Eagle Racing CDC charger is showing resistance numbers nearing 100.

So cycling them is mainly to keep the cells more evenly charged/discharged, right? Cycling don't help recover the lost capacity, I suppose?

Sorry for the numerous questions. I'm glad someone posted this topic, as I'm getting info-overloaded and brain-freeze from internet searches.

Access

The real 'killer' of these cells is heat. If they are heating up when you charge them, the rate may be too high and you may be shortening their useful life. If they stay warm or cool, you're probably okay.

Cycling helps 'freshen' the charge. As a charge, or a portion thereof, ages, you get some voltage depression when that charge is actually used. A fresh charge has the best voltage hold-up.

Chris_RC

ocrcraceway.com

73, using a Novak Smart Tary will take your cells down to .9 volts per cell. This is good because a nimh battery is only as good as your worst cell. So say you run and then you see how much voltage each cell has. One might have 1.2, 1.3 1.1, and 1 might have .9. SO the battery will only perform with .9 volts per cell. Also the battery peaks easiler so you dont get as much capacity. But the Smart Tray can ONLY be used with side by side batteries. So if you have a battery that is a stick pack, 3 cells X 3 cells vertical you cant use the Smart Tray. Best thing you can do there is a verry slow charge and a Integy 30 amp discharger.

deanR

Always Dreamin: I have to agree with chris^ OCRC is so much fun and I make a 5+ hour trip down there every couple weeks.

The only decent Nimh i have is an orion rocket pack 2700. Ive only cycled it a couple times and it charged up to 3108 mah last time I charged it. I am using a thunder power TP 610-C charger.

I will be making the switch to lipo in a couple days though. Now that i have a power supply i can use lipos at OCRC

emaXXman123

My Feedback: (1)

sorry to bud in but you would race in mod truck [&:] oh ya..i live 5 hours away from ocrc and ive been there haha you conl only use 2s lipos though and gotta be hardcase, but i bet you could get away with using a soft pack and a 3s...or ya sorry about that stupid fight thing we had about 2 weeks ago

Chris_RC

OCRC really doesnt have a mod truck class. They have a stock and super stock Sportsman and stock truck amateur and beginner. With beginner you can drive anything. SO if you are starting out with a Slash you dont have to run in the slash class.

brel

I am still on Nicads And the are twenty years old and run very well

emaXXman123

My Feedback: (1)

i voted BAN HIMMMM hahah sorry

73

Thanks for the replies. Please bear with my ignorance as I'm really trying to learn more about keeping these batteries healthy. [8D]

Yes Chris, my batteries are all over-the-counter stick packs. Since I only run my E-Firestorm in fun races with my buddies on our DIY backyard track, stick packs seem pretty much sufficient. To put them on balancer would mean I'll need to make them side by side, or at least break them apart... which is something I don't think I want to do yet.

-Having them on overnight slow charge (when cycling) is no problem for me, so that's a decent enough way to maintain them? Any recommended intervals, like every 5 runs or 10 runs?

-Read that slow charging & discharging enables the individual cells to take-in/put-out more evenly, thus I charge them at 0.1C during cycling. But u reckon discharging at 30amp is OK?

-I do not need the power that came with high amp charging, but will the batteries degrade if I regularly charge them 0.5C - 1C rate?

Chris_RC

There is nothing bad about charging at a low charge rate. For most people to get their batteries alive they would char5ge it at .5 amps then discharge it and put it on a tray. But since you dont hav a discharger that is the best thing for it. I have heard people say to get a c/15 charger and charge it for 15 hours to equalize it but I do not know where you can get them. If you find them a link would be nice. What kind of batteries are they? Like brand, capacity, cells, etc? Also what charger do you have? Bascially the higher the amp discharger the more power you get. But the dischargers only discharge to 5.4 volts so 1 cell might have .9 volts and 1 cell might have .6 and a battery is only as good as its worst cell. So without the Smart Tray there isnt much else you can do. SXS batteries also are faster because they have less resistence. I recently got a iNDi (integy) 30 amp discharger on ebay for $6 shipped and a Novak Smart Tray for $22 shipped. Also if the cells arent balanced 1 cell will tell the charger it is done charging when 5 other ceklls arent fully peaked.

73

Okay, I'm getting the picture slowly. At least one thing for sure is, I'm not exactly doing anything dumb.
Guess I'll have to get by with the less than perfect cell balance for now then, until I decide to strip the batteries and buy something like a Smart Tray.

The 5-charge-old 4500 is a Orion Rocket Pack.
The older 3700 is a PannSpeed.
The oldest ones are a GP3300,
and some "Team Speed Mind" Outlaw 3300.
They're all 6 cell stick packs.

My charger is the CDC Charger version 6, from Eagle Racing.
Charge rate is user selectable 0.1 - 7.0A
Discharge rate is 0.1 - 20.0A
Volt threshold is 3 - 15mV
Cycle number from 1 - 9 times
Etc, etc.

If you don't mind, could you suggest a maintenance routine, given the above limitations.

Once again, thank you for your time and patience. Really appreciate the lesson here. [8D]

Chris_RC

Do you want power or runtime? You have some pretty good batteries. I would:

Charge at .5 amps 15mV, discharge at 5 amps, now go to .5, 10mV, discharge at 5 amps, .5, 5mv, discharge at 5 amps. But you dont want to get any lower than 5mV. The lower the mV the more it fills the battery but it can risk overcharging. Bascially if you want to keep your batteries in great condition, discharge them as much as you can. Like say you run 1 time and you wont run that day, give it a cycle. If you want power charge at 1.2-1.5C and discharge at 20 amps and if you want runtime charge at .1-1C (C=capacity/100) and discharge at .1-10 amps.

Frozen72

I voted BAN HIM! :P[8D]

73

That's some very useful advises, Chris. Thanks a million, they're exactly what I need to know.

73

Can I double check this, because I may have understood this the opposite way previously.

So if the peak voltage threshold is set at 5mV, the charger will stop later than if the threshold was set at 15mV?

I had thought that to prevent overcharging, I set it low at 5mV so when the voltage drop the charger stops.
If I set it to 15mV, it would allow the charger to keep going until it reach that 15mV drop.
So that was wrong?

Access

The point of the 'peak detect' is to catch the very top voltage (dv/dt) after which dv/dt only decreases. If you can reliably catch this there is no reason to increase it more. It's a sloppy way to try to increase the post-peak charge and 15mV per cell is real high and you risk potentially never catching it, or more likely catching it too late, if your cells don't all peak at the same time. For perfectly balanced cells, as low as 3mV may work, for unbalanced 6-7mV may be necessary. Unless you are seeing false peaks, don't increase it, there's really no reason for this parameter other than to detect the peak properly and reliably.

For how much you charge past the peak, use the other parameters like 'peak delay' and 'top-off charge'. You'll generally need about 1-2 minutes of peak delay just to make it work, so don't go under that. If you want to charge a certain point past the peak, use 'top-off charge' to regulate that reliably and consistently. And keep it under 10%, unless you're doing a balancing charge. Again if you try to do it by raising the 'peak detect', who knows what percentage you will actually get here.