Eshrefov

Hello guys this is my first post here. I wasn't able to find any information regarding my concerns so I decided to get some insight here. My question is more about whether this is a sensible and possible combo in terms of it working okay and not causing electrical issues. From what I've seen it seems to be a bit more complicated than the Amp-hours being just your capacity/range but rather also determining the amount of AMPS the battery can put out. And here is where I'm confused because it seems that the Amp rating on the controller has to match the Amp rating on the battery and i can't seem to figure out what that is on a 48V12Ah battery with NCR18650B cells. Also I'm hoping to get around 15-20 miles without pedalling and i weigh around 70kg but from what i've seen 12Ah just about is going to get me there so I'm more concerned with the battery working ok with the controller. Thanks in advance guys !

2old

48/12 probably denotes 12s (series), 4p (parallel); 576 w-h (watt-hours) should provide you with 20 miles use at
18-20 mph (though the bike should be capable of 28 mph or so) unless you have steep hills, faster speed, headwind or a lot of "baggage".

Should have added that my guess was based on your using "decent" batteries in which 4p would supply in all probability your controllers needs (my 1000w, 48V kit with a 30 amp controller works well with a Luna 52V, 10-ah battery). Using anything but good batteries is foolish IMO.

chas58

you need to know the C rate of the batteries, and the current limit of the controller.

If the C rate is 1 (typical of the inexpensive batteries), the battery can't put out more than 12 amps continuously. Well, you can try, but it won't last too long. High quality batteries (often Panasonic, Sanyo, etc) offer models with a higher C rate. A C rate of 2 will give you max of 24 amps. You can look at Lunacycles or EM3EV.com and see what batteries they use for which power levels. EMVev tends to be more conservative (they have been in business a lot longer too) with their ratings.

The current doesn't have to match, but the battery has to be able to supply more than the controller will allow. To be safe, go for a battery that offers 30-50% more current than you need. Running a battery at its full capacity isn't good for its life span.

Your range is going to fall of dramatically with speed. If you really want to know your range, you can go to Motor Simulator - Tools and calculate it.

dilkes

The OP said it was a 48V12Ah battery with NCR18650B cells. These cells are rated at a capacity of 3400mah and a continuous discharge rate of 2C (6.8 Amps).
18650 Battery Review, Test, Specs 2017: Panasonic NCR18650B 3400mah Amp Limit & 18650 Battery Datasheet

A "48V/12Ah" pack is likely either a 13s3p (10.2 Ah) configuration or hopefully a 13s4p (13.6Ah). At a 2C discharge rate, the 13s3p would be rated at (2 x 3.4 x 3) = 20.4 Amps continuous while the 13s4p would be 27.2 Amps continuous.

Since sellers tend to overstate things, I would guess it is the 13s3p delivering 20 Amps, adequate but just barely for a 1000 watt controller.

2old

Dilkes, thanks; guess I don't know my "s" from a hole in the ground today.

Eshrefov

Guys thank you for your input. I'm aiming towards a capacity of around 12-13 rather than 10 (not fully specific because different battery packs come with different cells). The reason for going that low on capacity is because I honestly don't find me needing that much range for my commute plus the lower price and lastly because I'm looking at those pre-made packs with the fancy holders that take the place of the bottle. It just seems more practical and appealing to the eye. I was just worried about the controller working ok with the battery and not making it's lifespan shorter. So i guess its safe to say I'm going to need a controller rated for 20-25Amps right ? Thanks again !

Klaw

What model of motor is it?

NoPhart

My advice is "Go big or pedal home!"

With a 1000W/48V motor I'd recommend at least a 17.5Ah minimum. Your mileage may vary...

hisownself

you calculate power by voltage times amps drawn by the motor. Your motor can handle a certain amperage which is limited by the controller. The software imbedded in the controller may also limit the current. It's common to limit to 25A. So a 48V battery when discharging 25A will deliver 48x25=1200 watts of power. The battery capacity is 12Ah which is how many amp.hours of charge are in the battery. If you burn 25A continuously, then you can only run for 12Ah/25A or just under a half hour before the battery is dead. These are "rules of thumb" and actual performance is typically less due to efficiencies.