Looking for battery advice

[Meepsh]

Hi there, I'm not super technical so please have a heart. I'm building up an ebike with this motor and a 40 amp Controller:
https://www.cycmotor.com/x1-stealth

My goal is to have a bike that goes 25 - 35 mph (I realize the size/weight of the bike will factor into this) and my friend who is helping me is recommending 2 7/8 x 3 7/8 x 6 1/4g a battery that is 8.4 amp, 52 volt and 50 amp max continuous Discharge Rate:

"Also one thing that's real important with batteries, is the maximum discharge rate. The batteries like I have are rated at 50 amp max continuous. The six amp hour batteries that I've seen are rated at 30 amp, which is probably adequate for your application, but right on the line."

The battery he is recommending is large compared to the frame (2 7/8 x 3 7/8 x 6 1/4) and im looking for something smaller. Range is not super important (15 miles or so) as i can tote an extra battery. Any recommendations?

Thanks!!!!! - Darren

 

[Deleted member 4845]

You have chosen a hi-powered motor kit. 8 AH is fairly low capacity. Battery capacity will decrease over time, MORE SO with batteries capable of a high discharge rate. If you want to replace it every year or two, 8AH MIGHT repeat MIGHT be enough. I would get a bigger battery, not a smaller one.

 

[Meepsh]

You have chosen a hi-powered motor kit. 8 AH is fairly low capacity. Battery capacity will decrease over time, MORE SO with batteries capable of a high discharge rate. If you want to replace it every year or two, 8AH MIGHT repeat MIGHT be enough. I would get a bigger battery, not a smaller one.

Thanks man, appreciate the feedback!!!!

 

[CrossRoads]

Get a 20 amp-hour battery with 50 amp BMS. Most people start small when they enter the ebikes world and want more juice after more experience. To me, 20 amp hours is actually pretty small. I carry two 20 amp-hour batteries on longer rides. They only weigh 5.5 kg each, one of them just rides in my pannier. If you're coming from riding a normal bike, you want to think differently about weight. On an electric bike, a 5.5 kg battery feels like zero kg when charged and feels like 50 kg when dead.

8 amp hours, maybe good for 15 to 20 miles, sure, but wouldn't you rather have something capable of 40? What if you want to swing by a friend's place on the way home? What if you took a wrong turn? What if you forgot to calculate elevation gain into your mileage, which will eat up a lot more power than a mile of distance. What if you forgot to charge it the night before?

 

[ozzie21]

It looks like you've chosen a 52V battery. That is good. But only 8Ah? I wouldn't have though they even make a 52V battery with such a low Ah. I look at it this way. A higher voltage battery is like if you had a car and you put a higher horsepower motor in it or a cam, etc. Ah is like you put in a larger gas tank. If I had to choose between voltage and Ah, I'd choose Ah because that's where you get your range from. In discussing batteries with anyone I always recommend getting the highest Ah battery you can find and afford. Both more Voltage and Ah are good. It depends on what you can afford. Obviously more horsepower (voltage) and a bigger gas tank (Ah) need a compatible controller and electric motor to match. All of this costs $$$....