Wanted to bounce some ideas around and see what direction I should go.
I love my board and looking to upgrade it to a dual drive with killer range… Except I have an addiction to punching the throttle on the empty roads I encounter here in London (they exist!).
I know the pros and cons of Lipos vs Liions but I’m after a solution that minimises these compromises they have.
There have been topics about huge capacity Lipos (such as 22Ah Gens Ace Tattus or Overlander 22Ah batteries) and these would really work great for range and reducing voltage sag. However, having an 8Ah 9s setup myself I’ve noticed that (after about 200 miles) my acceleration has dropped and so has my top speed (35mph to about 28mph now) and I’m assuming that’s due to the reduced C rating my batteries have had over their usage? Not sure if its my VESC settings but that’s besides the scope of this post.
So I’m toying with the idea of Liions but even a big pack (12S8P) would still suffer from a lot of voltage sag with how I ride.
Should I just stick to high capacity 25C Lipos? Are there alternatives? The kicker is I want to keep everything under the deck (40" stiffy).
at 8p even saggy liion cells like the hg2 and 25r would no longer be an issue, since you’ll have 160amp! available, which I doubt any setup will even be able to approach before melting the vesc down to molten metal
@Hummie I did see a drop in range but I assumed it to be because I ride faster now. I also tweaked VESC settings to have higher motor and battery amps (80 each) and max Watts (1900) and I’m unsure if I pushed em too far.
@Idle they’re 3x turnigy 3S 8Ah 30C batteries. They’re all low resistance but I haven’t checked how much capacity the charger gets them too as AFAIK that’s not accurate.
@thisguyhere I was hoping to use 30Qs, they’re rated to 15A each right? So 12S8P would give me 120A? Seems a bit low? I have a £50 9-ply maple deck that’s quite stiff and w-concave. How much do you think I can fit underneath? I want to go BIG since liions are cheaper than massive capacity lipos…for science of course. I’ve a 70cm wheel base to play with (- space for 2 VESCs and a BMS).
@BigBoyToys thanks, you answered a bunch of my questions previously and I know you push things. If you and @thisguyhere reckon its fine then I’ll make the investment. How big do you think I can go? I’ve a 70cm wheelbase to fit everything and I don’t mind reverse mounting my morots…will get Carvons one day.
How much range are you looking for? You could use lower capacity/higher discharge 18650s so you wouldn’t need so many cells in parallel. A 12S8P of 30Qs would give you 160A discharge and 1065Wh which is like a 100km of range… I doubt you need that much.
Mine look like a doubled 12S4P. The cells are in sleds. The reason i went for such a big battery is because first i wanted to use harvested old laptop cells. And for that i had to use many of them in parallel because of the low current they can provide. But after a while i needed real power so i replaced them with the 30Q.
And it’s just awesome. You don’t need to care anymore about your battery. Just simply go as far as you want because your legs will give up earlier. And it is still a very usable board. It weight’s around 2,5 kg more than a 12S4P but that’s it. It’s configured as my speed board (long wheelbase, 60 km/h max) for the road to do long distance stable and fast.
Some pictures of the old version of the battery can be seen here. The new one simply has the 30Q cells.
But u have li-ion cells , and only 9s, and after 100 miles, and increasing the motor and battery Amps, you have a reduced top speed and acceleration I think u said.
Id Get the vesc recording to see what Amps ur doing and do more in series
With question three for @Ackmaniac it sounds like li-ion do degrade their c-rating a lot after 250 cycles. Cells lose capacity and discharge ability w cycles . another reason to go li-iron. The red headway cells have a high discharge ability and I’ve seen video of people overcharging and shooting w a bow and arrow or a hacksaw. No problem no fire