hot batteries

[[email protected]]

Leopard 3650
2- 3s- 2200 lipos
90a esc
Outboard from OSE

Each time I go out, the boat is sluggish and not fast. Sometime the throttle quits but then restarts right away on its own. When I open up the boat, the batteries and wires are very hot.
Why is this happening?
Is the motor too big, too small?
Is the ESC not big enough?

Thanks for any suggestions

[Panther6834]

What is the 'C' rating on the batteries?


~ More peace, love, and kindness would make the world a much better place

[[email protected]]

I use 60c and 50c
How could C rating affect heat?

Do you know about timing of the ESC? I have a program card for ESC and wonder if I change the timing.

Thanks

[Panther6834]

I use 60c and 50c
How could C rating affect heat?

Lowering the motor timing (through the ESC) could help...but, my guess is, the batteries are the core of the problem. A crawler will get 45 minutes on a 5000mAh pack, while your typical basher will get 15-20 minutes on that same battery. You'll be hard-pressed to get more than 4 minutes on that same battery in a boat. Why? Because the energy is 'sucked' from the battery a LOT faster.

The 'C' rating represents the battery's resistance...the lower the 'C', the greater the resistance. A crawler uses very little power, which is why a 35C pack is more than "good enough" for them. Your typical basher uses more energy in the same period, which is why it needs something in the 50-90C range. A 'pleasure' boat needs at least 60-75C, while a race boat probably shouldn't have anything less than 100C. When you use a battery with a lower 'C', as stored energy departs the pack faster than the pack can handle, it generates heat, due to the resistance. The greater the resistance, to the greater the heat generated.

Moral of the story: Get battery packs with higher 'C' rating.


~ More peace, love, and kindness would make the world a much better place

[HTVboats]

Some key info missing here. 3S series or parallel? KV motor? Prop load? Size and weight of boat? What are speeds your seeing and run time?
Mic

[jkflow]

Agreed, more info needed. Most likely it's a combination of capacity and C-rating, but no idea if you are running a tug or an FE.
Also, what is your definition of hot? Get a cheap temp gun, don't rely on fingers.

[[email protected]]

Here is more info-
28 inch wooden tunnel hull (previously nitro)-
Running 2-3s in parrallel
2200/ 60c
run time 4 minutes at up to full throttle
3650 kv
Do not know speeds or weight of boat- it is wooden
Definition of hot- cannot pick up batteries and wires to the touch!!
Do I have too much battery for the Kv?
Thanks for help

[Doug Smock]

Hello Brian, You didn't tell us what prop you're running.
If by "too much battery for the KV" you mean voltage, yes. Capacity, no. 3650 kv on 3s is a pretty hot set up without a lot of motor. Combine that with a 4 min runtime and 4400 Mah on board my guess is you are knocking the bottom out of those cells among other things.
How much capacity was left after a run? (You want 20% min, if you want them to last)
What are the motor ESC temps after a run?
2700 - 2900 kv would be a better choice or drop back to 2s prop

Have fun and good luck!!

[[email protected]]

Doug
That helps alot. The prop came with the outboard- cnc-3814250- 38mm.
Capacity after running is at 3.8v or so.
Never measured the temp of the ESC, motor, or batteries. Will have to figure out how to do that.
Will try 2s tomorrow
Thanks for help

[Doug Smock]

https://blog.ampow.com/lipo-voltage-chart/

3.8v/cell or so puts you down around 10 to 15% or so.

https://www.offshoreelectrics.com/pr...od=hh-dynf1055 or similar

135 to 140'F max is where I draw the line.

https://www.offshoreelectrics.com/pr...y-Cell-Meter-7 or similar

Good luck!

D.

[jkflow]

3.8V is a little more than 10%, it's ~40% and still plenty of minutes of fun left in the pack.
Agreed, 135-140F on the Lipo is about as high as you ever want to see it go.

[Doug Smock]

[QUOTE=jkflow;758612]3.8V is a little more than 10%, it's ~40% and still plenty of minutes of fun left in the pack.
Agreed, 135-140F on the Lipo is about as high as you ever want to see it go.[/QUOTE

You are correct. (difference between .4 and .04 old tired and a little dyslexic ) Personally, I don't ever want to see my batteries at that temperature. Mine are seldom much over 100' after a heat race.
The temperature reference was to Brian and in regards to the motor and ESC max temp. And personally at those temps, I'm working on getting them down closer to 130'. But to each his own..

[LibertyMKiii]

I'd probably start by picking up a low cost IR Temp gun (Amazon or Harbor Freight?). Check the wires, connectors, various areas of the motor, the ESC, and areas of the driveline incase of some high friction spots.
Heat is relatively unknown until you measure/read it correctly. To me 115F is too hot to handle, but ok for these electronics.

Connectors can be a restrictive point that causes heat. Lower mAh batteries have a tendency to come with connectors made for 40-60a applications.

What type of connectors are you running?