Hello,
I know this is something that was spoken a lot, but I would like to have some advices for my specific caracteristics.
As I understood, the higher the battery max regen you set, the weaker your brakes are.
I was using 12s lipo with turnigy 8 Ah 30C, and I had to change them because they inflate baddly. I was taking care for charging at 1C max and the battery current max was around 80. I think (but not sure), that they inflate due to a to low max regen setting (around 45 if I remember).
I bought new batteries (zippy 5,8Ah 60C) and I have set the regen value to 5,8 (so it charges at 1C right?) because I’am scared of damaging those ones. The problem is that the brakes are somehow too weak.
I precise that I have no BMS, just using the VESC for regulating battery voltage.
So here are my questions:
How low can I set my bat max regen without damaging the batteries?
Would a BMS allow me to set low value to give me strong brakes, by regulating the excess of current coming to the battery?
This battery is pretty cheap and looks good quality!
Too late to buy new batteries… I already got mines and don’t want to spend more for now. Also, I’m living in Mexico and it’s hard to find lithium batteries (or twice the price in the US) due to their restrictions on lithium batteries import. So usually I buy them when I’m in the states or europe but have to buy the right batteries so I can fly with it. (not sure that I could fly with this Panasonic module).
Also, this module has an interesting charge current, but the max discharge is not crazy. Even if actual C rates are hard to really know on lipo, with my zippy 60C, I have a theoric max discharge of 350A.
It is commonly said that 1C is the safe recommended charge current for Lipo. However, Some RC enthusiast will also claim that 2C is perfectly safe too. If you are worried, this can be tested in a controlled environment at home (if your charger is powerful enough).
To test battery, set the charge current higher, try at 2C, or even 3C, for MAXIMUM of 2 or 3 Mins Only and monitor your battery for defects / overheating etc.
Only do this experiement outside on non-flammable surface area.
WARNING: IF YOU IGNORE MANUFACTURES CHARGING SPECIFICATION THERE IS INCREASED RISK OF FIRE
If you don’t feel like doing the above experiment, then think about it this way. Charging your battery from depleted to full charge, over a period of 1 hour or more, using a LIPO battery charger is very different from the regen braking system in your electric skateboard. This regen brake system is pumping short bursts of high-ish current for just 5 or 10 seconds only. The current peaks high then drop off very quickly as momentum/load is reduced.
NOTE: The only time this theory isn’t true is when you live at the top of a very-long-steep-hill and you hold the brake fully on, but because the hill is SO steep & SO long that you are still moving very fast with the brake on fully. In this example, your battery is getting hit with high & sustained currents which is probably bad, but if you did the experiment above you will already know the outcome.
The other thing to think about is safety, from the perspective of safety alone you can easily answer your question. Take your pick;
Get hit & killed by the truck at the intersection at bottom of the hill because you could not stop effectively. or,
Possibly reduce the life expectancy of your consumable battery pack worth $100
I wrote more about this topic here:
TLDR:
Always set your battery regen currents to optimise brake performance & rider safety, not maximise battery life.
oh, and, If your battery keeps dying get a bigger one
Thanks for the recomendations, I also checked your topic about regen, and it’s actually what I was searching, interesting infos. (Thinking about dividing regen if running dual ).
I actually checked my battery specs from manufacturer and it says that it has a max charge rate of 5c. My last one was 2c aparently so it could explain the short life they had. I think I’m okay if I set max regen to -12. ( (5,8Ah * 5c)/2vesc =14,5). However I will make a few tests at this charging rate with smart charger.
It will anyway be better than my last config values that was way too high. It should have be set at -8 and not -40 (8Ah*2c/2vesc =8).
I’m curently running 3 sets of 4s batteries on the board, but have 6 more in the backpack, so I will try to make space in the box to fit 6 so I can double the value.
That’s about a 35A to 40A battery; lower the battery max. This might lead to puffing / inflation as you’ve observed.
You NEED to be sure what these numbers are, they are very important.
Those are probably 60A batteries
Don’t set this based on the battery, set this based on how fast you need to stop. The forward current I think is your problem, not the braking current.
While a BMS would help in many ways, it would not help in this way and could actually be worse if not used properly.
No.
The higher the Battery Current Max Regen you set, the weaker your brakes are at higher speeds.
At lower speeds, you get stronger brakes by lowering the “Motor Current Max Brake”
I was saying that I was not sure why they inflate, but you’re right, you have to be sure of values with those batteries.
Well, also when my board is stopped, the brakes are super strong… Of course, the faster you go, the hardest to stop. But actually in really steep slopes, even at low speed, the brakes are too weak if I set high bat regen max.
That what I’ve read, and It’s why I divide this number by 2 in my max current bat settings.
And why would this be marketing bullshit on Lipo and not in Li ion 18650? Any way of testing it?
Saying that a battery is a x A battery doesn’t really mean anything. You can define it by its Capacity (Ah) or voltage ( 3s) or by its max amps drawing .
I’m curently set at 95A on battery max current, same as motor in this case.
There is absolutely NO WAY that ESC can do 200A continuous and no way your batteries can either. Those numbers are inflated by marketing personnel, in order to make more money selling stuff.
Could you be more precise, and explain why this is to high for my specific case? Doing the maths, it’s not to high. If manufacturer lies on C rating, it’s changing everything but that why I have a marge.
And again, why do you think that Lipo C rating is not the real one, and Li ion C rating is the one they say?
WARNING: IF YOU IGNORE MANUFACTURES CHARGING SPECIFICATION THERE IS INCREASED RISK OF FIRE