Molicel p45b 2x 12s1p in parallel vs. 1x 12s2p


I did build 2 12s1p battery packs with new p45b Molicel´s and use them for my DIY foil drive (Distrelec housing, 75100, 6384, Instagram: beenee_foilsports). On flat water everything is fine, even one pack is able to get me foiling with a 1401and a small board, so I can pumpfoil where ever i want (that was the idea about 12s1p). With two packs 12s1p in parallel the power last 30-45min and i´m able to launch smaller foil like the Spitfire 1030, what is amazing (I’m 90kg :-).

The only problem is, that when I use 70% of the throttle more then 15 seconds, the 75100 reduces the power dramatically. OK the 2p is only 2x45A max discharge a the voltage drops even about 20-30% but its far away from the programmed cutoff (2,5V / 30V). I left the FOC and use BLDC right now (much better), the current ist set to 110A, absolut current 250A, Data shows a peak of 110A and an average of 20A, 3400 watts max, ESC Temp 40-60C max.

In flat water no problem, but in waves it isn’t really funny. I still double the nickel stripes of the packs, but this seems not to be the problem. The battery packs even don´t get hot at all.

Is a 12s2p pack a better choice (much more difficult to fit in the small housing)?

Should ich go back to 10s4p 18650 Sony Murata?

May by its the cold temperature, the baltic sea has still 6-8 Degrees a the moment, and the housing is more flooded with cold water when I use them in waves?

Already bought a Flycolor ESC 160 and going to exchange the 75100 (use them already in my Boogie and even 6384 they perform much better!)

What did you recommend?

Review of p45b by mooch sets the continuous discharge at 35A: Bench Test Results: Molicel P45B - 50A 4500mAh 21700 - Rechargeable Batteries -

so 110A (if it is battery current) is really stretching it for 2p packs if you use it for any longer period of time, but this isn’t your issue, most likely culprit is still esc overheating or undervoltage limitation of current, both done by the esc. Can’t really see why there is a big difference in waves, is the amount of riding at full throttle longer?

You can verify what happens either way by a log from vesctools app if you bring your phone along - or by changing the protection parameters for these two (one at a time.) Does the esc reach the limits? What do the curves look like when the esc reduces power?

Ok, so do you think the 2p is not the problem right? Will so some logging next time. There is a Bluetooth already build in, so I can get data with my mobile

Could it be that the 75100 reduces the power because it overheats?
I agree with above that logging will help you debug the issue.

You should be fine once you switch out the esc. I have the same setup and have not had any issues on 12s1p or on two 12s1p in parallel. I pull around 70-80 amps.

I am not familiar with your vesc but I believe that is the issue, unless your parallel connector is the problem.

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How do you operate the 75100? In Current Control mode via UART or Duty Cycle mode via PWM input?
I found the throttle response far more consistent with Current control mode and have not noticed a significant change in throttle position up to the moment when the Battery Limit Start kicks in.
Also you mentioned 2.5V battery cut off, is that the value for cut off start when the 75100 reduces power or when it totally shuts off.
What are the battery current limits?

No, the battery isn’t the issue, it’s something else on the esc side.

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It’s either max power or max temp that are being hit which then pull the power down.

Not likely max power as it comes after 15 secs and is different between flat and wave riding. temp is likely though, looking forward to some tests :grinning:

While the last run the hub broke :frowning: So no data. But i used a fixed 15cm prop from my tow boogie instead and I had no shut down issues with that. The Vaux folding prop has 18cm. Maybe the prop is to big, but that the one everbody is using!)