Losi 14.8 batteries **CRAP**

[mjderstine]

Hey guys,

I have a friend who just got two losi packs, the 14.8v hardcase packs. He charged them with the balance connected and they seemed good. He puts it in his DB8 and starts testing it out in his yard and driveway. he has the teckno rc conversion, and MMM 2600 system in there. he is geared at the stock spur which i think is 48 and a 18 pinion.

He got done with the first pack, and when he pulls it out its puffed. The cells, or one of the cells, has gone bad after one use. he said the temps were only at around 140 i think, and the fan on the ESC was on, but when he took the body off it stopped (went below 150). (how can you get accurate battery temps with a hardcase pack)

He plugs the next battery in to charge that, and after less than a minute of being on the charger it reads 0.00 volts! and the blue cable on the balance plug is busted out of the soldering job.
He spent over $400 on these batts and they are both pretty much shot, both are now puffed, and we were at the LHS having the guy call LOSI to see about a refund or exchange

i told him that maybe his gearing was a bit high and he should have been about 16t on the pinion.

Can any of you put some numbers in the gear chart for me and see what kinda numbers he would be pulling. I dont have the same car as him and dont know the numbers.

he was using some proline tires and stock spur, which i think he said was 48, and 18t pinion. he said he didnt want to use a smaller one because it already pulled wheelies on a start, and was "scary fast." he was absolutely amazed at the power this thing had, before the battery crapped out.

Any experience with these batts or gearing on this setup would be appreciated!

-MJ

[BrianG]

Without going into the calc, those numbers do look high. Assuming typical diff ratios, 48/18 is pretty tall gearing, especially on a 2600kv motor running 4s. I would probably go to ~14T on the pinion with that setup. If he wants to retain the speed he was getting, he'll need stronger cells to cope with the current. Might also help to turn up the punch control quite a bit to help reduce those large current surges if he does a lot of stop-and-go running.

[mjderstine]

well he is mostly a racer, but when he isnt racing, hes bashing. i told him that it would be better to go smaller on the pinion and he agreed the speed he was getting would be to high for the track, but he was also pretty concerned that he has the settings turned all the way down on the MMM< and with going down in gearing it will be nothing but a torque monster.

i think he still has stock diff lube in his center diff though, he should go lighter, what do you think would be a good setup for the diff lube?

[BrianG]

lol, I'm the last person to ask about diffs because I like to run ~120k in the center. I hate the front unloading, but I'm a basher.

[lincpimp]

Send em to me, I have fixed the losi HC packs before, the balancer wiring sucks, I add some strain relief to keep them from pulling out of the tabs.

As for the puffed pack, I can pull the bad cell out and just make a soft pack for him, he can use it or sell it off...

[mjderstine]

i will let him know, he should be at the track tonight, the guy at the LHS has the batteries now, and is going to try to either get him new ones or his money back. but i will also let him know what you can do too.

what are your thoughts on the losi cells? are they all crap?

[lincpimp]

Originally Posted by mjderstine

i will let him know, he should be at the track tonight, the guy at the LHS has the batteries now, and is going to try to either get him new ones or his money back. but i will also let him know what you can do too.

what are your thoughts on the losi cells? are they all crap?

Considering the price i would buy a pair of hardcase enerland packs, or mikes hardcase packs. Or just buy some decent soft case 4s packs, like Mike's or Neuenergy. I was not all that impressed with the Losi stuff, looks like some chinese cells in there. Zippy packs would most likely perform as well and be cheaper to replace if they go bad.

Get the LHS owner to send them back to horizon and get replacements, then your buddy can sell them off and get something better! For 200 bucks a pack he could have flightpower or comparable lipos. I think the hardcase draws alot of people, but I really do not think it is worth it.

Mike needs to get some generic sized hardcases so that people can throw their soft cased lipos in there. Or integrate a cover for his lipo trays.

[mjderstine]

well as far as i know all lipos are manufactured in asia somewhere. maybe they just ahve a poor supplier.

i told him he should have gotten something else, but i didnt know he ordered those until he told me they busted on him.

i told him he should get the SMC hardcase packs when they come out in a couple weeks. they are the same price as the losi ones and have better specs.

it would be nice if someone out there could produce some nice cases for softcell packs, specially because my track, and im sure others will follow, are not allowing softcase packs at races. i know it is safety overkill, but some of these guys seems to think lipos are grenades ready to go boom.

the only way hardcase is worth it, is if the track demands it. the SMC packs coming out should only be 15-20 more for a hardcase. not bad when you think about it.

[himalaya]

Have a look at details, if the same cell(e.g. the 2nd cell in a 4S pack) failed, its's time to check out your charger.

[mjderstine]

would a charger screw up like that and charge one cell incorrectly? he had the balancer plugged in while charging, i thought that would keep things relatively safe.

[BrianG]

I would think the hard casing would greatly reduce cooling, and since lipos don't like to get hot, would just increase the chances of puffing. I wonder if those Losi lipos would have been fine if they were just left open?

[mjderstine]

maybe? but who knows. has anyone done tests on hardcase lipo temps?

i would think that if you stick with stock gearing, or acceptable gearing the temps would remain somewhat low, and save the battery.