Battery Range

[edrios3]

Hello everyone, I am both new to the forum and new to E-bikes. I have a 20A/hr 48v battery and a mid drive 750watt motor. On my first run only got like 20 miles using pass 1-3 only. I notice that the amps would go from 0 to 8 to 2 to4 in a matter of seconds in other words erratic . What do you guys thing is the problem or what can I do to solve it. thanks for your help

[dean]

I'm a noob, but what was your starting and ending voltage? I don't pay attention to amps, just volts. Dean

[Louis]

Was the battery fully charged? Any new battery needs to have a couple of long charges at 100% to get the pack fully balanced, IMO. What was the starting voltage? What was the ending voltage?

[edrios3]

The Battery was 80% charged as recommended by Luna Cycle and it read 52 volts and the end it was reading 44volts my concern besides the range of a BIG Battery is that while in PAS 1 I read amps from 0 amps up to 8A at the same speed same pedaling effort same grade. there no reason why it would change so much and that contribute to drain the battery faster right?

[JPLabs]

Not sure anything is wrong, that result is certainly in the range of what might be normal, depending upon conditions.

Also critical to know, in order to decide if this is normal or not: What kind of riding conditions? Hills, dirt, sand, etc. How fast were you going? Big soft tires, or what? Etc. Headwind? Were you barely pedaling, or pedaling hard? Anything related to energy consumption for your ride. Tell us more about those things, please.

Was 44V:

• measured while moving at the end of your ride, or
• the saved minimum from the ride, or
• measured after stopping?

It should only be measured at rest for determining how much you used. Stop, wait a couple minutes for it to stabilize (at least) then check.

44V isn't quite empty for a 48V pack, in any case. That's about 3.4 V per cell (13S pack), which is more like 10-20% level if you measured it at rest, depending upon what cells you bought.

Amp readings actually do vary quite a lot while riding. Seeing current jump around while in PAS isn't unusual. Pedal power is very uneven through a rotation. Bike speed changes a little. You shift your weight and the motor 'feels it'. etc... All these things change the instantaneous torque on the motor, and thus amperage. It changes real fast, too. Fractions of a second.

[CraigAustin]

I agree more info is needed but disagree that it's close to normal. You don't buy a 20ah battery to get just 20 miles in PAS 1-3 on a BBS02, even at 80%. I would be severely bummed by that result and asking the same question. For sure the advertised range is double or triple that.

[JPLabs]

Craig,

Perhaps. But, on the other hand, for all we know he did 20 miles in the sand on a Schwinn Stingray. In which case he did real good.

[CraigAustin]

For all we know Giselle is sitting next to me asking favors. Pretty unlikely though.

[Louis]

The Battery was 80% charged as recommended by Luna Cycle and it read 52 volts and the end it was reading 44volts my concern besides the range of a BIG Battery is that while in PAS 1 I read amps from 0 amps up to 8A at the same speed same pedaling effort same grade. there no reason why it would change so much and that contribute to drain the battery faster right?

Luna doesn't really recommend 80% charges. What I read is that 80% charges can extend battery life. That said, I believe that every new pack should go through a few 100% charges for 4-6 hours minimum. Get that battery fully charged and balanced from the new build. THEN you can start 80-90% charges to extend the life, BUT don't forget that monthly full charge. I like a monthly overnight charge. If you've just been charging at 80% and never gotten the pack up to full charge and balanced I would expect poor results.

Do that and then JPLabs is spot on. Lot's of variables affecting mileage once the battery charge is sorted.

[Ein]

I find there is a huge difference in range depending on several factors. For example, how aggressive you ride, straight and level or hilly and how much you contribute to the "joules". That said, be sure your voltage instrument is calibrated and the best way to measure how much was left in the "tank" is to measure the Ahs necessary to refill the battery. There are various forms of power meters for that purpose. Don't measure the voltage too long after "resting". Li-Ion will bounce back and give you a false reading after more than 5 minutes. At about 3.1-3.2 V/cell, the battery is pretty much discharged.

[tonk]

Everything said above. Something that is not mentioned directly is that the cadence makes a diff also. If you find that you can keep the same approx' speed in a lower gear then by being in the taller gear is requiring more juice. Try to keep your cadence as high as is comfortable. Also you mention assist lvl 2-3. Unless speed is a priority drop gears & stay in lvl 1. I ride long distance, 15-50 miles with a 52v 17a battery pushing a BBSHD. I'm 240#, so no light weight, seating in an upright riding position both of which will require considerably more juice to move. When I'm going for max distance I fully chrg, ride a little more casually (slower) & turn Assist to 0 whenever I can. Finally, throttle use is a killer but if you have to use it, ease into it & only as much as necessary.