run time affected by junk battery/esc?

[jmini]

Hello everyone. Obviously im a nood to RC... blahblah.

i was wondering if there is a way to to check why my run time is bad on my truck. I remember a couple months ago my truck would run for close to 40-60 minutes. now it seems the run time is very low like 30-40 minutes IN THE HOUSE.

note:i haven't changed my set up what so ever on my modified hilux highlift, since. fxr-esc/35t motor combo

Is there a way to check if possibly my batteries/esc? is causing this?
i own two 3600 venom nimh battery packs and they seem to give me about the same running time. i check the voltage on a full charge and they're around 8.4v (common i assume). after running i checked voltage and they're roughly ... i wanna say 5. something.

I wanna say my battery packs are just getting old but im just exploring other options.

i cleaned my brushes and yet i still have the same run time. besides my batteries im wondering if my esc is bad? idk how i'd check that either if possible.

i know this is very vague info but any help would be appreciated. i can give more info if needed.

[Charlie-III]

The ESC basically either works or it doesn't.

It could be aging batteries, not sure on that though.

A better thing to check is binding in the drivetrain (loosen the motor so it's gear is disengaged from the spur, how easy does the rig move?) as well as condition of the motor bearing/bushing.
If something is tight, or you have a failing bearing, the extra drag will use up power faster, thus shorter runtimes.
Also make sure the motor pinion/spur gear mesh is correct (a very slight amount of play between the 2 gears), too tight can eat battery power.
Check the steering EPA's, if they've changed, a servo hitting a mechanical bind can also eat battery power.

How many cells are your packs?

[benoj]

i would have to say its likely your batteries getting old and you may be able to bring them back by cycling them a few times. i notice they are venom packs, those packs are usually hit or miss. ive had 3 of their 3000mah 7.2v packs go bad in easy half the time my cheap duratrax packs have

[crawlhog]

im going in part with charlie3 and benoj. i had the same problem and it was the old batts (nimh) try a new batt and see what happens, you can never have to many

[FreakyT333]

Definitely sounds normal for nimh, one thing that may help prolong their life is to avoid discharging them till completely dead. Just recharge them when you really start to notice power loss to avoid working them so hard.

[jmini]

Originally Posted by Charlie-III

The ESC basically either works or it doesn't.

It could be aging batteries, not sure on that though.

A better thing to check is binding in the drivetrain (loosen the motor so it's gear is disengaged from the spur, how easy does the rig move?) as well as condition of the motor bearing/bushing.
If something is tight, or you have a failing bearing, the extra drag will use up power faster, thus shorter runtimes.
Also make sure the motor pinion/spur gear mesh is correct (a very slight amount of play between the 2 gears), too tight can eat battery power.
Check the steering EPA's, if they've changed, a servo hitting a mechanical bind can also eat battery power.

How many cells are your packs?

I'm glad to hear esc's work or don't. Lol. It's working so we're good. Haha

My packs are basic 6 cell 7.2 3600 mah nimh.
Thanks for the input. I'll definitely check for any binding. (:

[jmini]

Originally Posted by benoj

i would have to say its likely your batteries getting old and you may be able to bring them back by cycling them a few times. i notice they are venom packs, those packs are usually hit or miss. ive had 3 of their 3000mah 7.2v packs go bad in easy half the time my cheap duratrax packs have

That's what I hear about venom packs. At least they were on sale for $22. Haha.
What nimh packs would you suggest? Obviously the higher quality the better. But what about, I don't wanna say "cheaper", but decently priced packs would you suggest?
Thanks so much for the reply.

[jmini]

Originally Posted by crawlhog

im going in part with charlie3 and benoj. i had the same problem and it was the old batts (nimh) try a new batt and see what happens, you can never have to many

Agreed. I'm sure having more packs would definitely save the life of each by letting them cool. I'm debating on getting more batteries. I don't wanna spend too much, "I know it's sin to say that LOL" but I just want decently priced packs with decent run times. 3600-4200 mahs.
Any suggestions? I saw tenergy 7.2 6cell 5000 mah packs on eBay. Any thoughts?
I appreciate your reply. Thank you.

[jmini]

Originally Posted by FreakyT333

Definitely sounds normal for nimh, one thing that may help prolong their life is to avoid discharging them till completely dead. Just recharge them when you really start to notice power loss to avoid working them so hard.

thanks for the tip. i always run my truck till it completely stops moving. at least try too anyway. after that I run it on a light i made to discharge the battery completely. until the light runs out is when i decide to charge the battery.
From that point i let them cool down for a while then charge again.

HERE IS WHERE IM NOT SURE. should i let the fully charge battery cool down (after charging) before i run them in my truck? OR, is it fine to just run them as soon as they're done charging (still warm)?
i've heard both sides but never really got an answer. I've searched a lot through this forum and it seems everyone is leaving nimh batteries behind for lipo .
again, thanks so much for the help.

[Charlie-III]

Multiple answers here.......

1-After charging, when the packs are warm, they produce maximum power. It's a good thing.

2-New packs, I would strongly suggest using CBP (www.CheapBatteryPacks.com) for packs. It won't matter on the battery chemistry, they are all good.

3-Don't wait for the rig to stop, just wait until the performance drops off enough to notice.

[jmini]

Originally Posted by Charlie-III

Multiple answers here.......

1-After charging, when the packs are warm, they produce maximum power. It's a good thing.

2-New packs, I would strongly suggest using CBP (www.CheapBatteryPacks.com) for packs. It won't matter on the battery chemistry, they are all good.

3-Don't wait for the rig to stop, just wait until the performance drops off enough to notice.

Sweet custome packs might be a cool idea and they're decently priced. Maybe on my next battery purchase I'll check this out.
So what about when discharging them? Wouldn't running my packs till theyre dead on my trucks the same as discharging them with another load, like killing it with lights or unmounted motor? Is this a good idea with nimh? I thought it was good practice to discharge completely till they're dead, letting them cool, then charge?
Correctly if I'm wrong, I'm just trying to set up discharge and charging procedures to prolong battery life and performance.
Thanks for the help.

[jmini]

Correction. Freakyt333 just mentioned not discharging them all the way. I'll keep that in mind. But, should I still let them cool down before charging?
Also, would charging a battery with life still left in them unbalance the cells?
Furthermore, what amps should I charge at? I've read that charging 3000mah should be charged at .3 amps, 4000mah to .4 amps, or 5000mah to .5 amps?
Would charging the nimh battery at lowest amps (.1amps) be considered trickle/slow charging? And when is this a good idea to charge at these low amps?

[Charlie-III]

For all my NiCD & NiMH packs, I run them until "performance drop-off" then store.
For my LiPO packs, I charge then store.

So far, my method has worked for me, but the packs are also stored in a relatively cool area.
All batteries will self discharge, temperature changes the rate. The warmer it is the faster the discharge.

As to "discharging til dead", running to performance drop-off is what you want. I would HATE to see people shorting a pack to "0" volts thinking this is OK.

Add-on....... letting a pack cool to ambient is best before recharging. If you are doing a "peak charge" before a race/comp, warm is good.

As to charge rates, I use "1C".....a 1500mah pack charges at 1.5A.....a 3000mah pack charges at 3A. Your numbers are off by "10".