hope i didnt ruin my new lipo's - RC-Monster Forums

josh9mille · **hope i didnt ruin my new lipo's -** 03.14.2010, 10:44 PM

was running my truck for a bit today and had to stop when my pack was run about 80-90% through. I unplugged my batteries and plugged them back in about an hour later to finish off my run. Normally i would have just charged up the batteries but since the MMM has lipo cut off i thought i might as well finish them off. well after like 3 minutes i noticed it was going really slow like the batteries were way below my 3.3v cut-off. Anyway im thinking since i unplugged the batteries and plugged them back in when the voltage was kinda low maybe the ESC didnt recognize they were lipos and went to the nicad mode? Is that possible? I really hope i didnt ruin them, i only have 3 cycles on them. Any ideas?

sikeston34m · 03.14.2010, 10:53 PM

How many cell count were you running?

The MMM always beeps the number of cells it see when you first turn it on.

It doesn't just jump to another mode. It's still in LIPO Mode.

Are you sure it wasn't just the LVC kicking in?

josh9mille · 03.14.2010, 10:58 PM

i run 4s and the MMM set to auto lipo with a 3.3 cut-off. Normally when the LVC kicks in it just stops. It was just running really slow and when i put that set of lipos on the charger afterwards it was reading way below what they normally are when i first hook up to the charger

sikeston34m · 03.14.2010, 11:04 PM

Quote:

Originally Posted by josh9mille

i run 4s and the MMM set to auto lipo with a 3.3 cut-off. Normally when the LVC kicks in it just stops. It was just running really slow and when i put that set of lipos on the charger afterwards it was reading way below what they normally are when i first hook up to the charger

They were reading way below what they normally are?

Did you have a volt meter? A cell voltage display?

What were they reading?

josh9mille · 03.14.2010, 11:15 PM

no i dont have a volt meter. the batteries read about 6.32 volts when i hooked them to my charger but that was about 30 minutes after i stopped running them so i think the voltage probably came back up a bit just from sitting.

sikeston34m · 03.14.2010, 11:20 PM

Quote:

Originally Posted by josh9mille

no i dont have a volt meter. the batteries read about 6.32 volts when i hooked them to my charger but that was about 30 minutes after i stopped running them so i think the voltage probably came back up a bit just from sitting.

If the resting voltage came back up to 6.32 volts, there shouldn't be any harm done.

They should be ok.

Balancing is always a good practice. Is your charger a balance charger or do you have a separate balancer?

I would check the balance on them when they are nearly charged again.

josh9mille · 11:29 PM

oh ya i didnt spare any money on the charger. Hyp Duo. However i do skimp on the batts, turnigy 5000 2s 30c. I would rather have a really good charger to charge cheapo packs than to have high dollar packs and a venom charger lol. I ALLWAYS balance charge, and they did balance out pretty good about 0.01v difference. However it did put about 70mah more back in which tells me i over discharged a little. I hope there is no long term effects though

josh9mille · 03.15.2010, 12:02 AM

what i would really like to know is why didnt the ESC shut down like it normaly does at 3.3v/cell? The batteries are not much concern as i got 4 of them shipped for only $140.

BrianG · 03.15.2010, 12:10 AM

When you plug in your battery pack, the MMM will assume a freshly charged pack, which is ~4.2v/cell. So, the MMM may see a somewhat depleted pack as a fully charged pack of lesser voltage. This is why it is best to count the beeps when arming so that you know what the ESC sees.

Finnster · 03.15.2010, 12:14 AM

You can force it to a cell count instead of auto detect if you always use they same voltage of batts.

If you plug in a nearly dead 4S pack, it may be read as 3S and set cut off V too low.

josh9mille · 03.15.2010, 12:44 AM

Quote:

Originally Posted by BrianG

When you plug in your battery pack, the MMM will assume a freshly charged pack, which is ~4.2v/cell. So, the MMM may see a somewhat depleted pack as a fully charged pack of lesser voltage. This is why it is best to count the beeps when arming so that you know what the ESC sees.

Ok, that confirms what i was thinking, thanks!

Quote:

Originally Posted by Finnster

You can force it to a cell count instead of auto detect if you always use they same voltage of batts.

If you plug in a nearly dead 4S pack, it may be read as 3S and set cut off V too low.

Ya i should probably do that since i only run 4s anyway.

lincpimp · 03.15.2010, 11:17 PM

Yeah, just set it manually for a correct 4s cutoff voltage. I have never bothered with auto lipo, but I never change cell count after i get a setup working.

I had the same issue with an almost dead flightpower pack. I ran for a while, let it sit then went back out. The battery had revived enough and cooled down so that the voltage was not dropping but it just did not have much punch. i finally gave up and put them on the charger and sure enough they were about empty. So it is always good to top off your packs after a partial run, cause unless you time your packs and know how long they run you do not really know where they are discharge wise.