Moscow Plus battery questions

[Silvercat]

Hi,
Curious re my C7 display showing about 53 Volts after a full battery charge on my Moscow plus 48 volt 16 amp battery. Also, once I reach about 18 miles, the voltage C7 display drops to below 50. At around 30 miles, it drops to about 47 volts, if not lower. Also, is it correct that the lower the voltage, the less power to the motor? I have noticed that after about 25 miles (voltage around 47) I have had much more difficulty climbing hills. On one short but fairly steep trail, hard packed climb, I lost power half way up. Can be dangerous.
Thanks for any feedback...most appreciated! Safe riding to all!

 

[Bitmugger]

Hi

I own a Moscow plus with the 16ah battery. Despite what was suggested about 54.6v from what I've seen with my own bike and what I've heard others report the voltage right off the charger is a bit lower. I get 54.1v when taken off the charger and others see similar values too I believe. If I let the battery sit (not on charge) a day and then use it maybe I see 53.9v or 53.8v.

I've only just broken in my battery with about 900km total on my bike so far. The motor cuts off around 41.7v after which I couldn't detect any real help from the motor on pedaling. I suspect around 41.5 or a bit lower the display itself will turn off. On PAS 3 on paved roads with hills I can get between 65km and 80km from the battery. The 65km was tested on a probably 5deg day (so pretty chilly) and when I was just getting the battery broken in and learning to ride the bike in the most effective way. The 80km was based on extrapolating from the remaining juice in the battery on later rides but I am confident in the right conditions (temperature, roads and my leg strength) I can get 80km. I should mention I live in a hilly area, the hills are low rolling hills but plenty of them and I am a heavier rider (250lb+).

Regarding speed vs voltage you are correct, the lower the voltage the lower the speed, likewise a 52v battery (which NCM says won't work but I think they are covering their butts, I will be trying a 52v battery if I get my hands on one) will make the motor even faster. The faster will translate into more acceleration for you and if you have a derestricted display (epiccycles.ca C7 display is unrestricted) you can reach over 40km/hr.

I have another thread where I discussed my battery life but I noticed that even when down in the 42v range while the motor is barely giving any assist, if you set the PAS to 0 and just use the throttle on the worst of the hills or at the stop lights to get you moving it's still very useful and much better than nothing as the battery regains a bit of voltage while sitting a few minutes between hills and will climb back up a bit, enough to offer some help on the next hill.

Here's my personal range chart for my Moscow Plus with an 16ah battery riding on PAS 3. I consider the useful torque pretty minimal below 43v so I consider that my cut-off for normal rides. If I am riding below 43v I'll be on "reserve" and nursing the bike home on PAS 0 or PAS 1/2. The battery discharge curves for our batteries is that the first ~80% of the charge is a roughly linear (very roughly) and then it starts to drop off sharply so bear that in mind too it makes my numbers very "approximate". As summer arrives and my legs get stronger and temps rise I am hoping to maybe ride closer to the high end of the range more and more or even get these ranges on PAS 4.

 

[jkvt]

I don't think any of that sounds abnormal, at least based on my experience. If a full charge is right at 53.0V, maybe leave it on the charger for a 4 or 5 hours after it's charged. That should balance charge. I don't think it is necessary often but may be from time to time.

If I pull the plug right after charging I'm usually right around 53.5. If I leave it on a few hours longer I've seen as high as 53.9 (once). I've wondered about this since I bought the bike, since it is slightly lower than expected, but others seem to have a similar experience. I've never heard of one of these bikes reading above 54V. I would be curious if anyone has. It might simply just be an accuracy thing with the voltage readout.

As for the mileage you are reporting at different voltages. That sounds pretty much dead on with what I see in milder weather and low wind. You can see my post here, 4th down in the thread, where I found very similar mileage values as you: https://electricbikereview.com/forums/threads/designing-battery-cover.37776/#post-366796

And as for the power, it definitely drops in line with what you are finding. In fact if you get into < 46V it really drops. < 46 I kind of think there is a change it might be trying to conserve power too, but that's just a guess. I've never had it cutout though. When you are going up a steep hill, I'd put the PAS down to 1 or something like that. If you have it way up, it's constantly trying to push a lot of watts through the motor to get you to a higher speed, which may not be possible on the kind of hill you mention and it's just building up heat in the motor which may cut it off after a while if there is a safety built in.

All in all, last summer I was getting about 55 miles out of a charge before the battery indicator was blinking, using the bike entirely on road with rolling hills at PAS 4. I haven't been able to really compare much lately. It's either been too windy or too cool, so far this year, to get a good comparison. Looks like you're in Canada too, so I imagine you're not seeing peak range since it's still kind of cool out.

 

[Fred]

Another way I have looked at range and battery consumption.

I too am no lightweight at 250lbs. With zero pedaling my experience says one will use about 20Wh/Km travelling on flat ground at speeds of around 25Km/H. I measured this on a small scooter I have that has a Cycle Analyst on it to measure Wh consumption. On my Amego Infinite+ (same as NCM bike), I always pedal and normally ride in PAS2 or PAS3. Under these circumstances, I believe I am consuming 10Wh/Km. from the battery. In other words, I am doing 50% of the work and the motor the other 50%. Since my 16Ah 48V battery can theoretically provide about (50 x 16) = 800Wh, the range is about 800/10 = 80Km. Same conclusion as reached by others. Obviously lots of variables, but this seems to be a good planning number.

(BTW I also have a 2nd 13Ah battery with the intent of taking it along if I am going for an extra long ride...I believe this would extend my range to 145Km. Only problem is that while the bike might do 145Km, I don't think my butt could!)

 

[Bitmugger]

Another way I have looked at range and battery consumption.

I too am no lightweight at 250lbs. With zero pedaling my experience says one will use about 20Wh/Km travelling on flat ground at speeds of around 25Km/H. I measured this on a small scooter I have that has a Cycle Analyst on it to measure Wh consumption. On my Amego Infinite+ (same as NCM bike), I always pedal and normally ride in PAS2 or PAS3. Under these circumstances, I believe I am consuming 10Wh/Km. from the battery. In other words, I am doing 50% of the work and the motor the other 50%. Since my 16Ah 48V battery can theoretically provide about (50 x 16) = 800Wh, the range is about 800/10 = 80Km. Same conclusion as reached by others. Obviously lots of variables, but this seems to be a good planning number.

(BTW I also have a 2nd 13Ah battery with the intent of taking it along if I am going for an extra long ride...I believe this would extend my range to 145Km. Only problem is that while the bike might do 145Km, I don't think my butt could!)

Very sensible math. I like the way you approached it.

I have dreams of writing some code for an arduino to monitor my battery voltage, temperature, speed and distance travelled and use some basic algorithms to predict how much real world range is remaining. I can get the voltage easily and have a GPS module I can use to get the speed and distance travelled, likewise temperature is a simple sensor. None of it is hard just adds up to a project I am not sure I want to fully commit to and then I'd probably have to eschew any machine learning approaches due to memory limits and figure out a simple algorithm using weighted averages and summarized data points. By the time I had it working I'd probably have gotten a pretty good mental sense of what voltage equates to what range for me.

I wish I could get the PAS level easily from the display but that would at minimum require me to tap into the serial communications and decipher the appropriate messages.