What would you do?

[pb4ugo]

I sold a pair of Protek lipos that only had three runs on them. Yes, really three runs in my B44. Before I shipped them, I charged to 7.8 volts (they were 2 cell packs), though I didn't hook up my balancer. The buyer used the first one with success and had the second one swell and his esc (Novak Goat) fry as soon as he turned on the switch.

I feel very bad, but am not sure if I should accept any responsibility and offer partial refund. I never abused these packs in the three runs I put on them. I'm also concerned because he didn't actually do the charging, his friend did. I really don't feel in any way responsible and he hasn't asked me for a refund, I'm just wondering if I shouldn't for some good mojo.

What would you guys do? Also, what do you guys think could be the cause of the problems? Could over-volting the Goat from overcharging the packs be a likely cause?

[gtxracer]

If he didn't use LVC it might have caused the swelling. Get more info, analyze it again, then decide. If it was a freak accident, help the guy out. If it was user error, give him your apologies and any advice he needs.

[sikeston34m]

Originally Posted by pb4ugo

I sold a pair of Protek lipos that only had three runs on them. Yes, really three runs in my B44. Before I shipped them, I charged to 7.8 volts (they were 2 cell packs), though I didn't hook up my balancer. The buyer used the first one with success and had the second one swell and his esc (Novak Goat) fry as soon as he turned on the switch.

What would you guys do? Also, what do you guys think could be the cause of the problems? Could over-volting the Goat from overcharging the packs be a likely cause?

Fried as soon as he turned on the switch? Highly unlikely if he successfully ran the other pack.

A single fully charged lipo cell is 4.20 volts, when overcharged, things begin to get critical at 4.35 volts. Let's look at this. 8.4 volts fully charged, absolute max before swelling, 8.7 volts. Almost ALL ESC's have some tolerance to being over volted. Especially if it's just .5 volts over.

If it were overcharged much more than that, you would have known it. Even without testing.

An ESC failure will damage a Lipo pack. And it not necessarily be the battery's fault. A short inside the ESC, faulting wiring, or a locked motor will produce the same results.

Something smells fishy. If I were you, I would ask alot of questions and get more information.

Knowing what voltage each cell is at, inside the "faulty" pack would help alot also.

Lipo packs that are over-discharged, or over drawn amperage-wise will puff also.

Don't blame yourself, and don't be too quick to blame the Battery. It is most likely, setup related.

[skellyo]

It's one thing if he charged them and could tell you the specifics of how he charged them. With him having a friend charge them, there's really no telling if he did something stupid or not. Unless he specifically asks for a partial refund, I wouldn't even think of offering him one unless he can specify the conditions in which the pack was charged prior to his use of it.

[George16]

I don't think you're responsible for it.

[lincpimp]

Lipos swell for 2 reasons, over charging and discharging past their rated limits.

So he either over charged the pack, or shorted it. I doubt the goat can pull enough to over discharge the packs during use.

My guess is that the esc crapped out and took the pack with it, he should have unplugged it quickly and saved the lipo.

Or they charged the pack without a balancer and really overcharged one cell.

Either way it is his fault, I would tell him to read up on lipos before he kills the other one. I have sold alot of lipos, and I figure that people buying them know how to use them. If not then they should not buy it. Kinda like blaming Jack Daniels cause you got drunk... really your own fault.

[sikeston34m]

OK, here's more information:

http://www.teamnovak.com/products/es...oat/index.html

GOAT BRUSHLESS/BRUSH CRAWLER ESC SPECIFICATIONS
Forward/Reverse: Forward, Drag Brake, Reverse
Input Voltage: 4-7 Ni-Cd/Ni-MH cells (1.2V/cell) or 2S Li-Po cells
On-Resistance: 0.0012 ohms* (brushless per phase); 0.0012 ohms* (brushed)
Footprint: 1.18” x 1.54” (30 x 39 mm)
Weight(w/o wires): 1.49 oz. (42.2 g)
Rated & Braking Current: 120 amps* (brushless per phase); 120 amps* (brushed)
Power Wires: 14-Gauge
BEC: 6.0 volt/5.0 amp
Motor Limit: 18.5-turn (brushless); 27-turn stock motor (brushed mode)
Discrete Steps: 512 Forward; 512 Reverse
Battery/Motor Plug: Tamiya (battery); None (motor)
Voltage Cut-off: 6.25 volts (when Li-Poly Cutoff Circuitry is enabled)

So this ESC does have a LVC IF it was enabled.

Here's an exerpt from Wikipedia on charging Nimh. (Simply to show the voltage tolerance of this ESC)

http://en.wikipedia.org/wiki/Nickel_...ydride_battery

Charging

NiMH Charge curve - The charging voltage is in the range of 1.4–1.6 V/cell. A fully charged cell measures 1.35–1.4 V (unloaded), and supplies a nominal average 1.2 V/cell during discharge, down to about 1.0–1.1 V/cell (further discharge may cause permanent damage). In general, a constant-voltage charging method cannot be used for automatic charging. When fast-charging, it is advisable to charge the NiMH cells with a smart battery charger to avoid overcharging, which can damage cells and cause dangerous conditions.

So the Novak Goat ESC works with 7 cell Nimh packs. A fully charged 7 cell pack will be at 9.8 volts when you first pull it off the charger. Plenty of tolerance for a 2S Lipo pack.

The Pack in question probably encountered a HUGE Amp load (dead short) OR No Low Voltage Cutout was used. If No LVC was used, then it was ran until completely dead.

[lincpimp]

I will bet that if we could see the esc it has terrible soldering and either the battery or motor leads shorted, and the moron in question left the pack plugged in. Or maybe he just left it plugged in overnight, but that would not cause the esc to go POOF...

Either way I hope he learned his lesson, cause it was expensive

[BrianG]

Personally, I think if the ESC fried, the current while doing so damaged the pack. Simple as that. Unfortunate, but part of the risk/fun really...

[MetalMan]

If anything, this sounds like Novak's fault and you should tell him to contact Novak... Other than that, you shouldn't (and can't IMO) do anything about it since it's not your fault.

[TDC57]

I would Man up and take care of it!. Not that you want to hear it , but that just what I would do..

One thing my DAD always told me is a MAN is MAN as long as he keeps his word, once a MAM losses his word he is no longer a MAN.. I live by this statement but that just me.. Sorry I'm different! , just ask anyone..

Best of luck in what ever discussion you make..

[skellyo]

Originally Posted by TDC57

I would Man up and take care of it!. Not that you want to hear it , but that just what I would do..

So how often have you sold something and given a refund/partial refund for something that the user broke or misused after they received it? It's one thing to work out something with the buyer when they can accurately describe the circumstances of the failure, but with them not being the one who charged the pack, how could the seller possibly feel responsible?

[hoovhartid]

Originally Posted by pb4ugo

I'm just wondering if I shouldn't for some good mojo.
What would you guys do?

The only way you would have any reason to feel responsible, or get any bad mojo, is if you knowingly sold something you knew to be bad....and you didnt. Its not your fault if he did something wrong on his end. I feel bad for the guy because we all know what its like to have crap go wrong, but I dont see how that makes you responsible for his misfortune.

[jayjay283]

I agree with Hoov, you know if you did something wrong and karma will come kicking in your door. If you sold him 2 nice lipos barely used and he messed them up thats his problem. I personally would tell him to send me back the lipos and refund his money just so I dont have to listen to his crap. I get enough B.S. from my wife lol

[TexasSP]

I also think your clean based on the information given. Idiots are everywhere and can mess anything up. I always get suspicious when "friends" are involved in the mix with no specifics.