Help, my esk8 shuts off when I climb a slope

How-Tos & Esk8 mechanics Esk8 Mechanics
#1

Hello everyone. See if you can help.
I have a build (Evolve gen2 bamboo board, FoxBox Unity, 10s4p VTC5, 2xRacestar 5065 200kv).
The problem I have is that when I climb a long and steep slope, the skate goes off. Then you can not turn it on again after a few minutes (I guess until something cools)
I climb to about 20km / h, and the HUD before turning off marks me 40A for the engines and 30A for the battery, which is within the safe margins for this build.
Any idea what might be happening? It may be a problem with the BMS, the battery or the Unity.
How do I find out? The Focbox UI app does not write any log and go looking at the screen while I go up to replicate the fault is dangerous …

Thank you!

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#3

That seems, but when it overheats, does the Unity turn off suddenly?

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#4

Yes, I think so too. Is it a discharge BMS or is it bypassed?

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#5

bms cutoff from voltage sag w/ high amp draw on steep slope? low volt vesc cutoff from voltage sag or low volt cutoff set too high?

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#6

its a discharge BMS. Last time it happens battery was at 70% charge.

My settings at the VESC are:

Battery max 60A
Motors max 40A

#7

so on a hill that’s around 76 total battery amps.
40a motor * .95 peak duty cycle = 38a bat limit per motor
2 motors * 38a bat limit per motor = ~76a battery continuous on hill

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#8

Thank you. My BMS I think is for a maximum of 60A continuous and the battery for 120A (30A * 4p).
What maxs do you advise me to put on the VESC?

#9

i’d try 25a or 30a battery and 60a motor and also check out what voltage is set for your low volt cutoff, because when you draw a lot of battery amps on a hill, your voltage will drop considerably.

#10

Try lowering Battery Max as @professor_shartsis mentioned. Maybe 40A which is 20A + 20A per side

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#11

if the bms has a problem when he goes over 60, then with 2 motors that battery setting should be less than half of 60 (less than 30).

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#12

Thank you very much!!! I’m going to try those maxs.

After a low volt cutoff the Unity remains off for a few minutes?

#13

if you drew a lot of amps for a long time, your voltage could stay depressed for a while, but it’s hard to say based on the info you mentioned so far.

for hill climbs the more you have in parallel the better.

#14

Understood :+1::+1::+1:

#15

also the lower your gear ratio is the more amps you’ll draw for a given speed on a climb.

#16

15T on motor - 38T on wheels 200kv motor, 97mm wheels

75kg

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#18

Where did the 10S4P come from?

#19

It have been built by a professional here in Spain. What I don’t know is how good that professional is…

The cells are VTC5, bought here:

https://eu.nkon.nl/sony-us18650vtc5-flat-top.html

I’ve reached the maximum number of replies a new user can create on their first day. So I repy you here…

Wow!!! Thank you very much for the work you have dedicated to my problem!!!

I’m going to try those limits and if I’m still having problems I understand that the problem will be in the bms or the battery, right? :point_down:

#20

^from the bottom left chart it looks like with 25a bat, 60a motor, you can do about 31mph on the flats and 26mph on a 10% slope. above 10mph on a hill you could easily draw 50a battery amps.

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#21

or It could be the low volt cutoff setting on the esc.

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#22

After trying the new limits and capturing the Focbox HUD screen, this is what I see

The battery has a terrible sag. Start at 70% up the slope and down to 17%. In plain it gets to 50% again, I go back up again and the battery indicator goes down to 15%, then I get an undervoltage error and it stops. All this in 5 minutes.

It look like broken cells, but they are new. The truth is that it happens since the board took a strong blow, the blow may have broken something?

.

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