Lipos seem to be "flat"...what could be the cause?
 

Hey guys,

I'm a little bit stumped with my setup...I'm running a 2 week old E-Revo with a Tekno Neu 1515 1.5D, MMM, and Tekin 3400 23C lipos.

Here's the problem...I had a similar setup in my old converted Revo...same esc, same batteries, but a regular smooth can 1515 1.5D. Since I've converted, I picked up the Tekno Neu, and while low end seems strong, the truck just feels "flat" on the top end...like it just doesn't want to keep pulling. The packs (4 of them) are roughly 5-6 months old, and have never been pulled down to the 12.6V 4S cutoff I have programmed into the MMM.

I've redone all of my wiring from the esc to the motor, and from the esc to the battery. The only thing I haven't replaced are the Deans plugs.

The truck feels flat with all 4 packs in any combination, so I don't think it's the packs that are falling off. I'm starting to think there might be an issue with the motor? It's got maybe 10 full runs on it. I've tried different gearing...22/58, 17/58, 22/64, 17/64, 22/68, etc and it just doesn't seem "alive" anymore.

The MMM is set for 0 current limiting, and has been recalibrated several times to make sure I'm getting 100% fwd throttle.

I guess I'm just looking for some ideas that I might not have thought of so far...maybe I should replace the Deans? Maybe somehow all 4 of my lipos have lost power? Is there something I can check inside the motor to make sure something hasn't gone awry in there? The truck is brand new like I said, and there's no binding in the drivetrain...I'm a bit lost at the moment.

I'd appreciate any ideas you can throw my way...

Hey there,

one possibility could be cold ambient temperatures... lipos run flat-ish in the cold and drain quicker. Just a thought.

Daf

Very true...although last night after I rewired everything, I had the truck and packs in the house, so they should have been around 70 degrees. Unless they were able to cool fast enough to affect the performance when I went outside to test it...gotta think it would take more than 2-3 minutes to cool that fast? Hmmm...

Another reason why you should ride in your living room.

Lipo's hate cold; my mini-t had serious issues on 3S and the mamba 8K when i was in Austria a few winters back.

Yes, lipos can cool very fast in the cold. Try running them in a sock or something that will keep more cold air from hitting the pack.

Huh...Yeah, I suppose that could be the case...I figured since they were in hard cases, and inside the battery trays in the E-Revo chassis, it would take longer for them to "chill out".

Maybe I'll try warming them a bit before I go out, and see if that has any affect on the performance.

Thanks!

No prob. Maybe try some sort of foam to block the vents for the battery trays, then "warm-up" the batteries before you run them WOT. Stum did a good demonstration of "warm-up" in the beginning of this video:
http://youtube.com/watch?v=85v85Pn3DMk

It sounds like perhaps it is batteries themselves. Can you temorarily parallel the other two packs if there's room?

If it comes to life then we know it is batts since the current is cut in half.

I had that issue with the mgm esc. It felt good bottom end but fell off top speed. I couldnt get the mgm to pick it back up??? I replaced it with a castle hydro and got all the power back . I dont know what happend and unfortunatly will never know b/c the mgm went swimming :no:

Odd. Did it voluntarily go into the pool? Or did you have to throw it in since it was scared? :lol:

No, I accidentally drove my truck off a bulk head into some brackish water and by the time I was able to jump in and get it[it was also 45 ºF out and was still working, I had to undress to just my boxers] The lipos caught fire and the esc went up in smoke too. It was a bad day!

Sounds like it...

So it turned out that the 3400/23c Tekin packs weren't up to the task of the Tekno Neu...my new 5200/24C packs showed up yesterday, and it was night and day difference! It was like a completely different truck. Temps were around 25 degrees outside, and there was no power drop off at all after about 10 minutes of running.

The Tekin packs seemed to run strong with the smooth can Neu, but once I bought the Tekno version, they seemed flat. Both motors are 1.5D's...could the Tekno version be pulling that much more current to make the 3400's seem flat?

i was going to suggest lasrger capacity packs, but looks like you figured it out already! good job!