# Calculating battery max for vesc with a li-ion pack

Looking to upgrade my board to vesc but having some difficulty determining the continuous current from the battery. I’ve been watching this tutorial: https://youtu.be/_mNnHp7sOBE which seems to use a LiPo battery to calculate (with C rating). Unfortunately, I have a li-ion pack which doesn’t have a C rating on it. Below are pictures of the labels on the battery. I couldn’t find a datasheet online for it and I bought it second hand so I don’t have the store listing.

Your best bet would be to remove that blue wrap and see which cells are inside. Then you can google cell model and see its discharge rate

I may have actually found the datasheet. http://www.hyybattery.com/Electricvehiclebattery_67.html

It says “5C discharge after full charge.” So doing the calculation in the video, I would get (4ah * 5C)/2 motors = 10A max discharge? Does that seem right?

I really don’t want to take off the blue tape as I will need to fly with this battery next month.

Where did you see 5C discharge? All I can see is 0.5C or 2A. That is way too low for any esk8 use.

This came from a paean H2B (cheap chinese board) so I would like to think that it’s good enough for esk8 but you never know with these cheap chinese companies

That can’t be same battery your battery has 4000mAh,this battery with 5C discharge rate has 4400mAh. That means different cells and different discharge rate

Looking at the specs in the link you posted, it clearly says “maximum discharge current 2000mA.” That means that you get one amp per vesc. The datasheet for the different battery lists 5C, and a maximum BMS discharge of 45A, which don’t match up either with each other, or the earlier 2A number. This is the problem with buying cheap undocumented batteries likely with fake cells. You have no real idea what you have, and thus no real idea how to treat it.

I’d say limit yourself to 10A per vesc. If you want more performance/range/whatever, save your pennies and buy a proper battery from a reputable source.

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So then what would happen if I were to pull too much from the battery? Would it get hot and explode or would it just stop working?

The cells Will get hot…depending.how long you push them past their max value a variety of things could happen…

They get over worked but not pushed past the point of no return and they die way quicker than needed…

U push them hard and then something melts amd the pack dies…

U push it to hard…they get too hot and then thermal runaway happens and then its nuclear melt down…

Probably not a lilely “explosion” like a bomb but a fire will start and you’ll be like “whats happening… Why is is my board smoking… Oh shit its on fire! Run!”

Oh well that’s fun. Is there any way to get the settings off of the currently installed esc or is it built into the hardware?

Really depends on the board, but overwhelmingly unless it’s based on vesc hardware/software, the answer will be either it’s in hardware, or it’s buried in some proprietary firmware.

Just set your vesc conservatively and check your pack during/after your test ride. If it’s hot, then you’re doing damage to your pack.

Yeah it’s one of those cheapo yiling ones that the old meepos use. I’ll start it at 10A and do a test to see if I can bump it up.

Honestly, with unknown cells, 10A per vesc (20A total) is probably pushing the maximum I would be comfortable with.

It’s just not a very large battery, capacity/cells wise, and 10A per cell is pushing them pretty hard if they’re not designed for high discharge.

Even quality name-brand cells that aren’t designed for high discharge top out around 7-10A before you start really doing damage.

Oh alright. This is my first board so I don’t really know what I’m doing. What would you suggest that I start at? Maybe 5A?

5 or 7. You could go straight to 10, but just be careful and check to see if anything is getting hot.

You should be aware that given the budget constraints and hardware you already have, this board is not going to perform impressively, unless you upgrade pretty much everything but the deck and wheels. There’s only so much you can do with a shitty battery and the cheapest possible vescs.

Switching from a noname ESC to a vesc will make it smoother and more responsive, but you’re limited by the battery, a LOT. Those vescs M.Hboards linked in the other thread are good for fifty amps. You’re planning to feed them a maximum of ten.

I see. If I were to upgrade the battery down the line, would I ever want to be pulling more than 50A? Just trying to decide if it’s worth an extra \$40 to get up to 100A.

The 4.20 dual is a better design than the 4.12 singles, but with your current setup that’s like asking if you need a Cummins 6.7 or a Duramax 7.8 to put in your vespa. You will not reach the limit of either, because you’re limited by your battery.

My last build had a 10s4p battery with genuine Samsung cells, capable of delivering 40A per motor, and it was absolutely fantastic. More power is definitely better - not only will it improve your acceleration, but also your brakes. Your brakes will be really bad with that battery, because your braking power is based on how much power you can regenerate into the battery pack, and that pack is only good for maybe two or three amps per motor of regen.

Alright, I just read through https://www.electric-skateboard.builders/t/new-user-looking-for-battery-read-this-complete-walkthrough-of-batteries/26010 and I see the problem. I think I’m going to run the current battery + esc through a clamp amp meter to see what it draws from the battery.

I guess I’m willing to put some money into this if I can make it a beast. Really all that’s left to salvage are the motors. Are the ones that I have decent? I believe they’re these: https://flipsky.net/collections/e-skateboard/products/copy-of-bldc-belt-motor-6374-190kv-3250w

Look at live data on Vesc at the erpm n add a resistance, maybe a glove isn’t ideal, and see what the voltage does at ten or twenty amp draw. Maybe not a glove. Bluetooth data while riding