Emax s110 scooter with 60v lithium batterie

[nicosp]

Hello everybody

I am new to this forum and new to messing around with e scooters, so please go easy on me :p

I have an emax scooter s 110. It comes with very heavy lead acid batteries, so i dicided to put in a 60V29ah lithium battery in it. ( i used a 60V29ah lithium ion battery from a niu scooter). The scooter is now +-100kg lighter and drove very great for a little time.

First day everything was great a rode about 10km no problem. Once i tried the max modus (it was used the get this heavy model uphill) the scooter shut down and didnt awnser for about 2 hours. Then i tried again and it worked fine. I figured not to put him in max modus anymore and i would be fine.

I drove another day again +- 15km without any problems. But now, the 3the day, when i drive in normal modus and reach a bit above 40km/h its shuts down but restarts imidiatly after and this while im driving...

Does anyone have an idea what could be the problem and how i could solve this ?
the sevcon gen4 controllor should be able to take 69V so i dont thing overvoltage is a problem.

[john61ct]

Likely a low voltage cutout, sagging under heavy load or at lower SoC

then recovering a bit, then dropping again, etc

[amberwolf]

The most likely issue is as noted above--voltage sag under load.


What was the current limit on the scooter the battery came from? The general info I found for Niu is they are about 2kw.

What is the current limit on the scooter the battery is in now? The general info I found for Emax is they are around 4kw.

If the former is lower than the latter, then the battery is unlikely to be designed to handle the demands you're placing on it, and will either need to be rebuilt to do so (changing out the cells, perhaps also the BMS depending on it's ratings), or paralleling a second battery pack of the same voltage (same chemistry, number of series cells) that can handle the rest of the current demands of the scooter it's on now.

If the general info I found is correct then the battery you have isn't meant to supply even half the power you need.


Another possibility is that the battery is not balanced, and some cells are so low that under load it shuts off to protect against overdischarge and damage that can lead to a fire. This type of problem indicates cells or cell groups that are old or damaged and would need to be replaced to fix it. Leaving the pack on the charger for at least overnight, and sometimes for up to several days or even weeks, may fix the imbalance temporarily, but only until it is discharged far enough to become imbalanced again.

[nicosp]

Thanks for the reply's !

As you both suggested i believe it could be a low voltage cut off

What is the reason the battery is limited to 2kw? Is it the size of the conectors and/or cables?

Might the problem be that i welded the small cables for the battery on to the big ones, and the small ones cant handle the current needed for the motor?

If i find a way to connect the big cables directly on the battery might this help ?

Thanks for the suggestion of the 2nd battery, but since this is a hobby project I'm working on, I would like to avoid having to invest in a 2nd battery

thanks a lot

WhatsApp Image 2021-01-08 at 22.14.24.jpeg (208.94 KiB) Viewed 27 times

[SlowCo]

That is really a very bad soldered connection especially the negative wire
Why not solder them both directly into the connector?