1000w with 35a > Battery drain?

[murbot]

I've got a Rad Mini 4 with the upgraded 35a controller and display. I'm upgrading the motor to either 750 or 1000. Still have the original 48V 14.0Ah battery.

How much quicker should I expect the battery to drain?

I have a spare wheel with a 500w motor I can swap in for longer rides But would like the stronger motor to be able to get 20-25 solid miles that will be some slow off road and some road. Not sure if I'd be better off with a 750. I mean, will a 1000 also burn out the overall life of the battery even if I'm not going full throttle all the time?

Thanks for any help or suggestions.

 

[m@Robertson]

Forget changing the wheels and motors. The current draw will be the same. That is dictated by the controller. Changing to a higher-rated motor will only swap in something better able to take on the extra current without frying on, say, a very long hill.

You can increase your range by being judicious with your power usage. the benefit of a 35a controller is you get stronger acceleration. Thats what the amps give you. Thats also where the fun is... so its all up to you.

Are we talking about a KT controller? You can dial back the amps on those. But that setting is the enemy of fun.

 

[murbot]

Thanks. Yes, the KT-LCD8H. I've testing adjusting settings with the 500w installed to lower the power for PAS levels, but the only thing I can change that still allows the speedometer to work is the overall stop speed. Every other setting and it sticks at zero when the motor is engaged, then reads about 2.4mph when rolling with no power. I just limit to 12-15mph at campgrounds.

The 750 drop in motor arrived yesterday and I opened it today. It's a new design that looks like a 500 inside the case. I'm suspicious so it's going back and I'm getting the Bafang instead. Just working out whether to go with the 750 or 1000. Feel like if I get the 1000, I'll feel like it's more than I need, but I'll always wonder if I get the 750. Probably gonna be the 1000.

 

[m@Robertson]

The new 750w Bafang motors - assuming we are talking about a G060 fat motor - have smaller cores and yes they look like 500's. The performance issues you are having sound a lot like you have some bad P settings. What does your settings screen look like? Thats one really nice thing about the 8H is it has that single-screen settings display.

 

[AHicks]

I think you're going to find the 1000w motor is going to have a different plug on the motor cable.

And I agree regarding the likelihood of some messed up parameter settings, or possibly the need for an external speed sensor if you don't already have one of those installed. The early Bafang motors need an external sensor. The later ones have the sensor built in to the motor. In either case, the white wire on the motor side of the controller needs a signal from a speed sensor. It doesn't care where it comes from....

As far as 500w vs. 1000w power usage, my experience is if both motors are running in similar bikes that are side by side, both should be showing about the same wattage in use. The 1000w is not going to use any more power when doing the same job as the 500. The difference is, when you give the 1000w enough power to leave the 500 in it's dust, it's going to be using a LOT more power.....

So how much more the 1000 will use is on you and your throttle thumb....

Oh, and the stock battery is fine handling 1000 watts. I've been running a 2017 Rad City with the stock battery, a 35a KT controller and a 1000w MAC geared hub motor for years now, without a minutes trouble. Range in a fairly hilly area using PAS 1 is an easy 30-35 miles.

 

[m@Robertson]

I think you're going to find the 1000w motor is going to have a different plug on the motor cable.

Made more complicated by the fact Bafang is phasing in new connectors into their production, and motors with both old and new are mixed out there in the market at the moment. Electrobikeworld has adapters that will go from old to new and back again, but they aren't cheap. Also you can look at pics of some of their motors on sale and see the new plugs on them. Its a threaded/screw-on 3-pin job now.

 

[murbot]

Installed the 750 OEM and only get about 24.8 top speed on flat ground. Def has more power than the 500 that got 22.2mph top speed.
Speedometer jumps to up 49mph as soon as I stop pedaling or release the throttle and the torque is too much off the line, but still tweaking settings. Finally got most things working. Each change either breaks PAS or throttle so it's been slow making adjustments. I'm regretting not getting a Bafang 750, but might have had the same issues.

Going to install the stock 22a controller that came with the bike along with the 750, the swap with my spare tire/wheel that has a 500w motor to see if there's any difference with that config.

I only got 17.5 miles with the 750 and the 35a ctrlr last weekend. Admittedly, I hit the throttle harder than usual at first to test, but also needed to more than usual because PAS wasn't transferring power when we slow crawled over rocks/roots. Motor would engage, but wouldn't have enough power the way it does on the road. Needed the throttle for a lot of the trail stuff.