Rize RX – Hits and misses new owner version

I'm looking for feedback on the RX battery. Now, it may be that it's performing as it's supposed to but I feel that it looses percentage rather quickly. I've charged it to 100% and ridden it in PAS 1 up a gradual hill (nothing steep) for about 2.8Km. I'll arrive at my work and the battery will have lost between 3-5% of its charge. Maybe this is normal but I'm reading other posts where battery percentage holds around 100% for awhile before dropping off. Are all batteries (of the same Ah and W) equal or can there be variation between?

I'd love to know what other RX or RX Pro riders are usually getting for their range? Do you find your percentage drops immediately or holds and then drops? How far are you getting on a charge (starting % - trip - ending %).

As well, I can't seem to make sense of voltage. I was down to 22% but my voltage was at 47.3v. Looking at the battery v/% chart I would have thought it would be closer to 43v. On another ride I was at 33% and my voltage was at 47.8v.

Any feedback would be greatly appreciated.

Thanks!
 

theemartymac

Active Member
I'm looking for feedback on the RX battery. Now, it may be that it's performing as it's supposed to but I feel that it looses percentage rather quickly. I've charged it to 100% and ridden it in PAS 1 up a gradual hill (nothing steep) for about 2.8Km. I'll arrive at my work and the battery will have lost between 3-5% of its charge. Maybe this is normal but I'm reading other posts where battery percentage holds around 100% for awhile before dropping off. Are all batteries (of the same Ah and W) equal or can there be variation between?

I'd love to know what other RX or RX Pro riders are usually getting for their range? Do you find your percentage drops immediately or holds and then drops? How far are you getting on a charge (starting % - trip - ending %).

As well, I can't seem to make sense of voltage. I was down to 22% but my voltage was at 47.3v. Looking at the battery v/% chart I would have thought it would be closer to 43v. On another ride I was at 33% and my voltage was at 47.8v.

Any feedback would be greatly appreciated.

Thanks!
The percentage reading is all but useless. The voltage chart method is better, but it is still affected by temps, etc, so the battery will spike back up a volt or two after your park for a few minutes. Peoples charts tend to vary by up to 10% but 47V is definitely still at or above 50%. 48V batteries should charge up to roughly 54V full, and <40 Volts is functionally 'dead' and approaching the cutoff voltage.

My RX battery drops off very slowly, but my RX Pro with the color display drops off far too fast. Each bike will still get near the rated 100+km range on PAS 3 if I'm contributing at least half the 'assist' myself. I am certain I can easily exceed 100km if I use PAS 2 and ride responsibly (but what's the fun in that? ;-) ).
 

AHicks

Well-Known Member
At 150 miles or so, I don't have that many charges on my bike yet, but I did notice one charge where the voltage seemed to drop off quicker than I thought it should have. Radio control experience taught me to be suspicious of cell balance in cases like that. That there are some cells that are not completely charged among those that are fully charged. Anyway, I put the charger on and let it go to green, unplugged it, let it sit overnight, and plugged it back in. Sure enough, it took more charge. That's not that unusual for new batteries that haven't been used/charged much and it hasn't happened since.

Agree watching the voltage (vs. battery %) is the better plan. I charge at 46v. There's not much left at that point, and I don't have to worry about voltage sag kicking out the LVC (turning off the power) when crossing a busy road for instance.

Cold weather doesn't help a darn thing either....
 
Thanks for your replies. So just to clarify, if my percentage reads say, 22% but my voltage reads around 47v, I should go with the voltage over percentage and assume I have more in the tank than the percentage alone suggests?
 

AHicks

Well-Known Member
If you understand that the bike is going to shut down/quit at 40-42v, you can see that at 22% indicated or 47v indicated, depending on which you get used to using/looking at, you can suit yourself. There's just not a lot of battery left either way you look at it!

FWIW, many avoid riding the battery down to exhaustion as it's generally agreed it's hard on the battery from a longevity standpoint. Worse, if you ride it until it quits and your a few miles from home - you're going to have a long ride.
 

theemartymac

Active Member
This is just my own strategy, but I might suggest that you ride the bike at least once until you begin to notice the power decline. Due to the shape of the power drop off curve with lithium batteries, at higher assist levels it will be pretty obvious and noticeable once it truly enters the last 20%. Once it starts to noticeably drop off, you can still expect to get 10-15kms anyway at low assist levels. When I tested my RX this way on a long 80km ride at average of PAS 5, it started to noticeably decline at 65kms. I made it home fine staying at PAS 5 with very little assist left. It still showed 20%, and read 42v after I parked it for 5 mins and unpacked, and I did even crank it up to max PAS 6 for the last 1/2km of the ride and gave it full thumb throttle on top of my own pedaling and it didn't cut out (motor still pushed quite hard too, but I could feel it fading in real time). While I did not have any cutouts, I suspect I was getting close at that point, and didn't feel the need to risk damaging the battery.

I also did another 80km test ride at PAS 3, and I was able to finish at 35% and just about 45v. I normally try to keep the battery above 45V/40% whenever I can for longevity, but I have total confidence that I can run it down to 42V in a pinch. Most battery kits seem to be dialed to cut out somewhere between 36V and 40V, but as AHicks suggested that can happen suddenly if you try to goose the throttle and it dips below that point momentarily. If you start to notice the power drop off unexpectedly on a normal ride, just lower your PAS level and ride conservatively (no hard launches or steep hills), and I'd be confident you can squeeze a fair bit out of it at a consistent pace before you are stuck riding old school style.
 

theemartymac

Active Member
Here is what a lithium battery curve looks like for a newer 52V battery. A 48V will be about 4-6V lower across the graph, and this is slightly exaggerated for illustration purposes. You can see the power drops off fast after 80%, and never actually reaches zero due to the voltage cutoff. Since any voltages above 48V generally won't be felt (the stock controller won't overvolt unless you unlock that), you won't notice the drop off at all until you are under 20%, but then it should be quite obvious. This is why newer 52V batteries are popular with 48V motors as they give you an extra 10% or so above 48V before they noticeably decline. The overall range doesn't change much as the cutout voltage also rises by 4-5V, but they maintain that ideal power output for longer. https://www.powertechsystems.eu/wp-content/uploads/sites/6/2018/11/LiFePO4-vs-Lead-Acid-Discharge-Curve-EN.pngLiFePO4-vs-Lead-Acid-Discharge-Curve-EN.png