Problem over heating Batteries on BJ-26

[Eagle_one]

I"ve been having problems with my Blackjack 26 Electric.

After running around 8 to 10 runs around the course I open the cover and check the batteries, motor and speedcontrol for heat. The speedcontrol and motor are around 100 degrees F.

But my batteries are running hoT to a point where it is melt off the plastic on one of the batteries. One battery is around 155 F the other was 200+.

I've replaced the speedcontrol but it still does the same thing. Everything is stock.
I've been using 4200 & 3800 Nicd batteries.

I was wondering if the motor could be the problem? I've also had problems with my speedcontrol cutting out at full speed, half speed works ok. That is one of the reasons I changed my speedcontrol.

Any help would be appricated.

[SJFE]

Ok first thing 100 on the motor and esc is well under the danger limit. Don't get worried untill they get over 125 toward 130 and up. With the normal power system temps I suspect your problem is with the batteries. It sounds like you have dead cells in those packs. We will need to know how old and what brand they are in order to be sure. What happens is when a single cell goes bad in a pack it becomes a resistor. It then heats up very quickly. The pack may apear to take a full charge but it is not. The problem with your esc cutingout is most likely due to the voltage on bad packs dropping under the heaver amp loads in the uper and of the throttle range. Brushless ad all FE boats for that matter are extremely demanding on batteries. You need to buy quality brand new packs. My advice it to buy a new set of good quality packs and go test. That is really the only way to trouble shoot yout problems.
Good luck.
Tom G

[Eagle_one]

The 4000 cheap batteries are only 2 months old. That is the latest one that got up to 200 degrees+ and other side battery was 155F.

4200 DTX was around 6 months old and that one was over 200+.

I'm charging the batteries with a Duratrax Intellipeak twin Plus charger. It takes around 1 hour to charge them up.

Will the hot low voltage battery kill the motor or speedcontrol?

The battery that gets hot has a voltage drop from 8.55 to 6.57.
The battery that's around 155 degrees F has a voltage drop from 8.55 to 7.95.

Thanks for your quick response.
I don't want to go through another speedcontrol.

Bill

[Apples1]

sounds like your chargeing them way to fast, i would try a 1amp charge that should take about 3 hours from dead, this means the discharge rate is slower and therefore lower heat, i will only charge my batts at 4amp for a race when i need the extra boost of speed,

Good luck

[SJFE]

At this point it's time to dispose of all the over heated packs. If you continue to run Nimh packs buy them from a web site that will allow you to spec them . Use deans bars, quality wire & be sure the vendor will stand behind the product.

[RandyatBBY]

The heat shows the damaged parts. Stuff that is cool is OK. Non Matched cells in a boat is a NO NO, they must be matched.

[Eagle_one]

Thanks for your input. I was miss matching the batteries some of the time but I was running both 4200 batteries when one side got over 200 degrees.

I was running 3800 with a 4000 at times or a 4200 with a 3800.

The motor and drive flex shaft show no sign of resistence.

Today I replaced the motor with a new stock motor and ran the boat for 6 laps and then checked for heat. The hottest the batteries got was 132 degree's F.

I'm buying 2 new 3800 batteries and then I'll see what happens. I'm hoping the batteries will be less than 132 degrees. I might of had a motor problem that was causing high amp draw.

I'll make sure to pull the boat back as soon as I see it start to slow down. This I know will help save the life of the batteries.

As far as the charging rate, my charger has a charging rate at 3.5 amps. It will charge two batteries at a time. It takes just over an hour to peak charge.

I also have a Hobbico R/C Multi-Charger should I be charging at 50mah, 100mah,
250mah or 500mah rate?

Bill

[obrien]

If you are dropping the voltage down to 6.5 volts, it sounds like you are running the batteries too long.

[Apples1]

3.5 amps sounds ok, you just NEVER want to charge at a rate higher than the the Batt you are chargeing has MAH ie, 4200 = 4.2 amp max, any higher and you run the risk of damage over time, ......unless you have money to throw away and are racing go for it. i made the mistage of charging at 6 amps (bad advice from LHS) great preformance ......for about 4 months.

That was a great way of throwing away $200.