48V 1000W eScoot Shunt Mod question

[KiDuLt]

Hi Everyone.

I'm from Australia,
and I got this little Bullet 48V 1000W Scooter.


I decided to purchase this to be able to go to work, without using petrol anymore. (5kms to go to work, 5kms to go home).

It's a little chinese 48V 1000W (1500W peak) scooter that I got from eBay for $399 USD.
Features are :

- Batteries : 4 crappy 12V 12Ah SLA from China :


- Motor : MY1020 48V 1000W/3000RPM/26.7A :


- Speed Controller : DMHC 48V/1000W 30A with two "options" (Double Speed & Anti " Out of control ").


The scooter works well. I will add a little speedometer on it, and this little device that seem to be interesting due to all its functions :


I'm just a little bit disappointed as the '50km/h' top speed claimed by the vendor is more around 35-40Km/h to me. (Will be confirmed in a few days with the speedo installed).
I'm only 50 kilos and I really feel like this little guy have a bit more of power, but for some reason can't unleash it.

I created this post to possibly discuss about this kind of scooter, and hopefully learn about it since I found it a bit difficult to find information on the Internet.

I have 3 main questions about this little scooter.

1) That speed controller has 2 "options".
- Double Speed. Is it what makes the scooter slow when the " Turbo button " is off. And run normally when this button is on ?

- Anti Out Of Control. Is it what makes the throttle unresponsive when the scooter is going down a hill, already almost reaching the " 50km/h" claimed by the vendor ?

2) Could the Speed Controller limit the power of the scooter, stock from the factory ?
All I found on the Internet about those things were a couple of guys, " beefing up " the traces on eBikes Speed Controllers, and doing a " Shunt mod " such as in this video :

https://www.youtube.com/watch?v=1PotpG-cVoU

Are those two mods that easy ? (I solder heaps of components, on circuit boards and stuff, building flying machines, but I have no knowledge whatsoever about those speed controllers).

Thanks for joining the thread and leave a comment if you feel like sharing a bit of what you know !

 

[Ianhill]

I suggest you get a load of 18650 cells and run it at 49.2v 12s pack could break out into 2 6s balance leads and dual charge leads to make it easy to charge as a dual 6s pack and then you could keep the original controller (battery display will be wrong just use 2 low voltage alarms on the balance leads) and will go like stink and climb any hill and 10kg lighter, I run the same motor on my scooter and it climbs extreme gradients, I suggest you go lithium as sealed lead acid won't deliver the amps needed and keep the volts up I did run the exact scooter u have in 36v form and had a range of 4miles where I live lots of steep hills, I built my own 10s9p lithium pack and my range is over 12 miles with a third capacity left. My top speed at 41v is 29.98 down hill and average 18 normally I plan a 61.5v booster circuit soon I have the lithium cells just need the time the motor will take around 60v max on a flat gradient low load situation and go around 30mph, Iam around 70kg by the way

 

[KiDuLt]

Hi Ian and thanks for your comment !

For sure a homemade 18650 batteries pack will be one of my upgrade on this little vehicle.

It's definitely the way to go. I keep learning about how to build my own pack.

I also wondered, could I just use four 5000mAh 3S Lipo ?


This wouldn't for sure allow me to charge the batteries with the actual charging socket, but I'm just thinking, 4 of those would weight 2 kilos.
My four SLA batteries probably weight 12-15 kilos at the moment. So the gain weight would be very good.

The capacity would only be 20Ah with four Lipos, so it would be approximately 60% less than the current 46Ah provided by the SLA.

Not considering a new charging system, and basically a total range divided by 2, could this be an option too if I can't build a 18650 pack at the moment ?

 

[Ianhill]

I hate to break it to you but that scooter is 48v 12ah its will have 4 12v 12ah lead acid in series's, The way sealed lead acid is tested is with a slow drain over 24hrs and because we flat the battery within an hour you won't even have 12ah it be more like 9ah and the battery's be very slow, lipo packs are great high discharge if you have no space but a scooter does have space so you can run lithuims in parralel to get the same high discharge 80a continuous and peaks of 150 if needed a sealed lead acid battery the voltage drops under load making the motor slower lithium keeps the voltage higher for longer meaning I can still pull a mean wheelie even after 1 constant discharge, I soldered my pack but it takes extreme skill not to heat the cells, solder a fuse wire to each cell on cathode and link all the anodes out 6mm copper wire and built up cells linking all the fuse's and into a 10s9p pack, but I know your battery tray is massive so Sky's the limit for you.

 

[KiDuLt]

No worries if you break the " RC Lipos idea "

I'm not afraid of soldering at all. I know that you must bring the heat very quickly and get the job done on each cell in order not to damage it with the heat, even if spot welding would be the best way to do it.
I can do that.

My concern is more about getting a bunch of good 18650 cells, learning about BMS and how to put everything together. And also, how I'm going to charge the pack.
But I keep reading and watching

Thanks once more for your comment.

 

[KiDuLt]

The little scooter has been great but climbs the hills a little slowly.

I decided to open the DC Motor Controller and identify the shunt.
It was 2 little piece of wire about 12mm long soldered next to each other on the board.

I decided to add a tiny bit of solder, to join them, on each extremity.
I tested the scooted and could notice a little increase of torque.

I decided to add the same quantity of solder and now I have two nice and shiny little blob of solder on each side of the shunt.

I know that this could harm the speed controller, so I didn't go crazy with the amount of solder. I can now notice a considerable improvement in the scooter acceleration.

I am planning to put the speed controller into a new metal case, with a 80mm fan added to it for better cooling.

My question is, is it an obligation to make all the traces beefier, by adding a copper wire, when the shunt mod is done ?

 

[Ianhill]

Its a wise mod not gonna cause no harm Im glad you found a good result your happy with, My next project will still be a scooter evo citi 36v brushless hub motor overvolted to 70v with a ebike controller I found perfect for lifepo4 very wide usuable discharge voltage 72v->40 with a 20s pack good discharge rates a headway 40152 and fast as stink I imagine.
I need disc brakes so I can convert to a set of shimanno hydraulics levers and calipers I have lying around cuz the razor e300 brakes suck at speed.

 

[KiDuLt]

36V to 70V sounds crazy to me ^^

Now that the scooter has a decent acceleration, I am collecting 18650 batteries.
My next upgrade will be a homemade battery pack.
I only got 6 Samsung 18650 at the moment. I found them in an old battery pack and was surprised since they are all at 3.70V.
I need about 70 more and I'll start building my battery pack

What kind of motor will you use for your scooter if you're planning to use 70V ?

 

[Ianhill]

To test a lithium it needs to be charged then calculate the discharge either with a set load and a timer or with a hobby charger I use the charger method much easyier, I went through 400 cells all over 3.5 volts only 90 had over 1.5ah, some where floating at 3.7v bit add a load and would fall to 3v in under 0.1ah so to check the health of a cell discharge it as the standing voltage means nothing

 

[KiDuLt]

Well I just learnt something again !

I'll use my iMax B6 to do a discharge test on all cells.