Battery issues

[BigJay32]

Hey guys, i am new to FE boats and I've had my Blackjack for about a year now. I bought a pair of 6 cell DTX 4200 ni-mh packs with it, they worked great at first, probably had 15 to 20 runs on them, then I played submarine and they got wet, on the next run after a dryout and recharge 1 cell in 1 pack got hot enough to swell and melt the heat shrink, i chalked that up to being submerged. Since then I have purchased 2 more of the same packs with the same result after 10 runs or so. I also replaced the esc as i had a spare around and the reciever due to the glitching after it got wet. Its always the 3rd cell back in the pack that swells and overheats. I still have one of the original packs in use and it works great. I usually run the boat untill the packs show signs of discharge probably 8-10 mins, is this to long and causing the cells to overheat??? Are these not the right packs to run in this boat?? I now have a pair of 7 cell 3300 ni-metal packs and they work great, packs are barely warm after a full throttle run with the same runtime. My setup is all stock, the only change I've made was to set the timing to high with the programming card. I have never charged at a rate higher than 3 amps the batts are warm after a charge but not hot. I am getting frustrated here as these packs are $50 each. $150 in bad packs=upset wife!!!! Any ideas???? Thank you in advance!!!!

[LiPo Power]

Hi
If possible swich to LiPo, lower your timing to normal, run your boat and check for temps.
Robert

[Apples1]

i'd swith your timing to normal, 10-12 min sounds a bit high with 4200mah but if you pulling it back in when it STARTS to show signs of slowing probable ok, IS DTX the brand of cell?

[BigJay32]

To lipo power,,,,, thank you for the info, I will set timing back to low, temps are usually just warm, except for when the 1 cell goes bad, but I will throw a temp gauge on after the next run.

To Apples1,,,,yes DTX is the brand of cell they are Hobbico/duratrax cells, the guy a my LHS told me if I werent going LIPO right away that these cells were the way to go. In retrospect I'm not sure I agree with him. THANKS

[Fluid]

As the OP discovered, his LHS is not the best place for reliable information about FE boats. AFAIK there are no really good NiMH packs being offered anymore. Even just prior to the legalizing of LiPos for FE racing, NiMH cell quality was getting spotty. IME Hobbyco, etc. packs were always mediocre performers in high draw brushed FE boats - the switch to BL motors really spelled the end for NiMH for all but low-powered use. Even high-end NiMH racing packs from 3-4 years ago would lose a cell from time to time under the demands of BL motors no matter how well they were treated.

It is very difficult to estimate run time without using a stopwatch. I would bet that the 8-10 minutes the OP thinks he is running is not very accurate. If his cell temperatures are not high and he runs anywhere near hard, 10 minutes is a long time.....

LiPos really are the best way to go today, even if current NiMH cells were decent. Budget cells from places ike HobbyCity are available for less than the OP's quoted $50/pack and seem to be up to today's RTR power systems. That's the way I'd do if I was starting in the hobby today.



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