Battery for multiple motors

[AC-EUV]

As per my other thread I am building an electric standup quad/scooter and would like to make it 4 wheel drive

I currently only have a 48v 13ah hailong ebike battery with 30amp BMS powering a chain driven rear axle (with a 48v 1000w my1020 motor) but ideally I want to add two hub wheel motors on the front two wheels for more power up hills and on sand beaches

I just need to know if I keep it all at 48v what size BMS battery would I need to power three motors if for example each motor was 1000w
So in total the quad would have three 1000w motors being used by the battery

Is it just a case of getting a battery which can handle at least say 30amps for each motor? So a 90amp total BMS on the battery?
So far I can only find hailong style batteries up to 40amp BMS at 48v or is this when I would need more voltage to go 4 wheel drive?

 

[E-HP]

I just need to know if I keep it all at 48v what size BMS battery would I need to power three motors if for example each motor was 1000w
So in total the quad would have three 1000w motors being used by the battery

Is it just a case of getting a battery which can handle at least say 30amps for each motor? So a 90amp total BMS on the battery?

Assuming the battery itself, and not just the BMS, can output the total amps required, then yes.

 

[bengxe]

How heavy is this thing and how fast does it need to go?

1000w at 48v is only about 21A, so that's your minimum requirement from the battery and BMS. If you have 3 motors that are each drawing 21A you need a battery/ BMS capable of at least 63A, and 90A would be a pretty reasonable safety factor.

The motor kv/ wheel diameter you select will have to match the speed of your rear wheels perfectly. Maybe you can adjust your gear ratio to match.

If you're actually running that MY1020 at only 1000w or 21A, you may want to try a controller swap for more amperage before investing in 2 more motor systems. That motor should be capable of 2-3x that safely.

 

[AC-EUV]

How heavy is this thing and how fast does it need to go?

1000w at 48v is only about 21A, so that's your minimum requirement from the battery and BMS. If you have 3 motors that are each drawing 21A you need a battery/ BMS capable of at least 63A, and 90A would be a pretty reasonable safety factor.

The motor kv/ wheel diameter you select will have to match the speed of your rear wheels perfectly. Maybe you can adjust your gear ratio to match.

If you're actually running that MY1020 at only 1000w or 21A, you may want to try a controller swap for more amperage before investing in 2 more motor systems. That motor should be capable of 2-3x that safely.

So this quad cart/scooter isn't actually that straightforward

I have built a standup quad/scooter out of an old kids quad bike which I chopped up and modified heavily so that the handlebars drop down and also lock up into position. I also have a cage which I built which bolts onto the back and when the handlebars are dropped down the whole thing then becomes a motorised pull along beach cart for taking stuff down to the beach

When the handlebars are locked up into the upright position (and the cage/box removed) it becomes a standup scooter quad which also has a golf bag attachment to ride around the golf course as a golf buggy.

I have actually already upgraded the controller to a flipsky 75100 V2 pro programmable vesc controller so I could setup two profiles, a fast one for golf buggy/scooter mode and a slower mode for when it is in pull cart/beach cart mode at walking pace. Also the vesc allows me to adjust the throttle curves which I really like for the cart mode at walking pace.

The problem I am having is when on really deep soft sand the rear wheels are just digging a bit too much and spinning on me when trying to pull it along in cart mode (slightly compacted flat sand it was great) but the softer stuff and uphill it struggled.

I also tried to ride it across the compacted wet sand across the beach with me on it (just for fun) and it nearly did a good job but the power just bogged down on me a little bit. Also when I tried to ride it up a hill (with the cart box on the back too) it really struggled to pull uphill,
Which got me thinking it could be great if it had all 4 wheels being powered for a bit more traction in wet sand and for pulling up hills.
I still need to play with the throttle curves though as I am thinking this may have been a reason why the power bogged down on me a bit as I had set it up to be less aggressive on initial thumb throttle response

My main issues I'm thinking now are..

My battery is only a 48v 13ah with a 30amp BMS so I may need a higher amp discharge battery
And I think I definitely need the front wheels to help power me through sand on the beach (whether I am riding it as a standup scooter or pulling it along as a beach cart)

I was thinking of buying two more of those flipsky controllers and running three of them all together the same

But I really didn't think about the rear wheels power needing to match the front ones

Either that or I just put a hub motor on all four wheels but obviously that will start getting expensive

Ideally would like this thing to be able to ride along on anything with no restrictions, deep sand, steeper hills, grass, golf course ect

 

[bengxe]

I guess I'll rephrase my question, how much does it weigh/ need to carry and how fast do you want the fast mode to be? If it needs to be significantly faster than the walking mode you may need to figure out a way to vary the gear ratio to avoid smoking the controller when it's loaded down and crawling through sand. Does the VESC allow you to change current limits on the fly like you do the thottle mapping?

You don't need to match the power front to rear, but you do need to match the free speeds so they aren't fighting each other. This is probably less important if this thing will only run on sand and grass, I was imagining a road vehicle.

The VESCs are rated by phase amps instead of battery amps, so that 100A rating is more like 30A max and even that is optimistic from what I've read. My point is your controller is still nowhere near maxing out that MY1020. You may be better off with a bigger VESC and bigger/ more paddly tires.

I'm still curious how much reduction it has, and the diameter of the wheels. Pictures would be nice.

 

[AC-EUV]

I'm guessing the quad on its own weighs around 55kg like a standard mini quad weighs and I'm guessing maybe 65kg with the box on the back.
Rider weight I would want to be anything up to another 80kgs max
Wheels are 10" in total with tyres, It has a 13 tooth front and 68 rear sprocket
I would want it to go up to 25mph max speed, no need to go faster really, it goes around 16mph at the moment on pavement

I didn't realise Flipsky 75100 V2 was only 30amp controller at best! I did ask in this forum a while back if it would be suitable and I'm sure I was told it was so went with it.
I can adjust current limits on the vesc app from phone and has profiles which can be setup with max speed ect, so I have one setup with max speed of 12kmph and one set at 35kmph for fast and slow modes which I can change by my phone app.

It's nearly working really well I just want to refine it a bit and make it a bit better

See pics below of it in beach cart mode and golf buggy/scooter mode

 

[AC-EUV]

I guess I'll rephrase my question, how much does it weigh/ need to carry and how fast do you want the fast mode to be? If it needs to be significantly faster than the walking mode you may need to figure out a way to vary the gear ratio to avoid smoking the controller when it's loaded down and crawling through sand. Does the VESC allow you to change current limits on the fly like you do the thottle mapping?

You don't need to match the power front to rear, but you do need to match the free speeds so they aren't fighting each other. This is probably less important if this thing will only run on sand and grass, I was imagining a road vehicle.

The VESCs are rated by phase amps instead of battery amps, so that 100A rating is more like 30A max and even that is optimistic from what I've read. My point is your controller is still nowhere near maxing out that MY1020. You may be better off with a bigger VESC and bigger/ more paddly tires.

I'm still curious how much reduction it has, and the diameter of the wheels. Pictures would be nice.

See Pics above