New battery faulty?

Ros

Finding my (electric) wheels
Oct 30, 2016
9
4
South East
Hello, long time lurker here.

About 18 months ago I bought a second hand Pro Rider e-Wayfarer folding bike, which was originally bought in April 2013. It had a 36v 10ah Phylion battery, which was giving me about 13/14 miles (depending on terrain, weather and how I rode it)

More recently it has started to run very low when I did the trip to our nearest large town - a 12 mile round trip, so I decided it was time to invest in a new battery. I decided not to have the original re-celled, as it was still good as a backup.

I bought this battery http://enerprof.de/shop/batteries/ebike-and-pedelec-batteries/enerpower-pedelec-battery-36v-145ah-522wh/ from the retail arm of Enerpower in Germany. It has Samsung INR18650-29E cells.

I was hoping that with a brand new battery and the increase in Ah I would get a range of around 25 miles

It came a week ago and after switching it on briefly to make sure it worked, I charged it fully (7 hours with my existing 2 amp charger) and then the next day I did my 12 mile trip and was disappointed to find that it was down to 1 bar on the display well before I arrived home. Mindful of not over stressing the battery, I walked it up the last steep hill to get home.

I'd read that a battery sometimes needs a few charges to reach full power, so I persevered. I have now charged it 4 times and this last time I tried a 30 hour charge, in case there was a balancing issue.

I have seen a very minor improvement - the last 12 mile ride today it was fluctuating between 2 bars and 1 bar on the last half mile before home.

I have measured the voltage after charging and it reads 41.5v, exactly the same as the Phylion does. On my third ride when it was on 1 bar it was at 36v and today on 1 to 2 bars it was at just under 37v.

It seems to stay much longer on 5 bars than the old Phylion, but then when it starts to lose charge it seems to drop off far more rapidly than the Phylion did.

Is it time to think of returning it to Germany?
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
19,991
8,173
60
West Sx RH
Hmmm !!! Doesn't sound very clever . Genuine 29E's should be a lot more capable.
My 2 x 3yr old 29E 09 case dolphin's give me 25/30 mile range a bit down from the 45/50 they originally gave.
 
D

Deleted member 4366

Guest
It doesn't sound like genuine 29E cells, though 36v is still half full. I'd expect about 20 miles of normal cycling to get down to that voltage or 40 miles from the complete discharge unless you're using the throttle or max power excessively.
 

Ros

Finding my (electric) wheels
Oct 30, 2016
9
4
South East
I generally only use the throttle when I need to make a fast getaway - I have a couple of busy roads to get across. However, in pedelec mode I normally have it on the top assist setting. But I have been riding that way with a 4.5 year old 10ah battery and this new battery isn't giving me much more.

The battery is advertised on the website as being Samsung INR18650-29E and the battery is labelled as having these cells. I thought Enerpower were a fairly bona fide German company?

When I was using the Phylion, the lights on the bike display would tend to go out in a fairly linear way from 5 down to 1. This battery stays on 5 for a lot longer, about 9 miles, but then reduces quickly down to 1 within the next 2 to 3 miles. Would this be symptomatic of one or more failing cells?
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
19,991
8,173
60
West Sx RH
It is possible that there may be weak cells / cell string though the only way to know is to open up and check with a meter when depleted, in your case not a good idea if you are looking to get back to the seller under a warranty claim.
 

Ros

Finding my (electric) wheels
Oct 30, 2016
9
4
South East
It doesn't sound like genuine 29E cells, though 36v is still half full. I'd expect about 20 miles of normal cycling to get down to that voltage or 40 miles from the complete discharge unless you're using the throttle or max power excessively.
That statement that "36v is still half full" was incredibly useful. I hadn't recharged the battery after the last ride, when it was at just under 37v and showing 1 to 2 lights on the bike display.

So, on Wednesday, I strapped my old battery on to the luggage rack (as backup) and made another trip into town - to find out how far the new battery would take me.

When I first turned the bike on, the display showed 5 bars, but this quickly dropped to 2 on the first short hill. To my complete amazement, I got there and back on the new battery and it was still flicking between 3 and 1 bars on the display when I got home and the motor was still as lively as when it was newly charged
That was a total of 25 miles ridden. I checked the voltage again and it was 34.5V.

I took the bike out again yesterday, again with the spare battery on the back. I went 2.5 miles, when there was noticeably less power and the display was mostly just 1 bar. I turned round and came back home and had to pedal quite hard, with the motor continuing to run, but giving very little assistance. The battery was still live and showing 1 bar and I checked the voltage when I got home - it was 33V.

So that was a 30 mile range, with about 28 miles on a good assist level. That's pretty much what I had hoped for when I bought the battery.
(18 of those miles were with the additional 4.5kg of the old battery strapped on the back.)

However, I'm still struggling to make sense of what is happening.

1. Did the battery recover in some way when I left it at 37V for 2 days? Can these cells bounce back or does the BMS continue to function even when the battery is not charging or on the bike?

2. I am puzzled that I seem to have full power (5 lights) for about 9 miles, then it rapidly goes down to 3 or less, but then stays at this level with good power for another 19 miles or so.

3. My bike display is an analogue one. I understand the 5 lights are only a rough indication of what is really happening, but what are they measuring? I had assumed the display was a primitive voltmeter.
 
D

Deleted member 4366

Guest
When you draw power from the battery, the voltage goes down, and when you stop drawing power, it bounces back. This is know as battery sag. How much sag you get depends on the power of the cells. Different cells sag different amounts. The amount of sag for whatever cells you have is proportional to the amount of power you draw, so you will see the battery go down one or two levels when climbing a hill, but at normal speed on the flat, there won't be much sag.

The controllers with LCDs often have a damping factor programmed in so that the battery display doesn't show sudden changes in voltage. Instead, it shows a moving average, which gives a better idea of where your battery is.

Its a bit like in the old days when the fuel gauge in your car went up when you went round a left corner or were facing downhill. Now the electronics damps out that sudden movement to show you an average, or it does it some other clever way.
 

Ros

Finding my (electric) wheels
Oct 30, 2016
9
4
South East
Thanks d8vh for that very clear explanation. Thanks to Nealh too.

So, based on what I have learned from you and what I have observed, I have come to these conclusions:

1. When the battery arrived, the cells were either out of balance or had not yet reached their full potential.

2. I have several hills, one of them short but steep, just before I get home - so I shouldn't take too much notice if the number of bars on the display is low when I get home.

3. On my old battery, once it got down to 1 bar on the display fairly solidly, it would cut off soon after. This newer battery (and better cells?) has a much longer 'tail end' and I will have to rely more on how it feels to know if I'm close to running out.

4. The battery now seems to be performing as I had hoped it would. Just in case there is still any balance issue, I have just left it on the charger for 3 days. From now on I'll charge it normally and disconnect it soon after it is charged.

I think what I need to do now is to go on a long ride (25 miles plus) and see how I get on.
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
19,991
8,173
60
West Sx RH
Take your spare battery with you if thinking of running to lvc to get a idea of possible max range for your riding style. Running to lvc I don't find an issue as cells don't drop much below 35v, as the battery lvc tends to be set much higher then 31/32v of controller lvc.
 

topographer

Esteemed Pedelecer
May 13, 2017
559
216
Mid Yorkshire
2. I have several hills, one of them short but steep, just before I get home - so I shouldn't take too much notice if the number of bars on the display is low when I get home
If you switch the electrics off and back on again after you get home you may see a bounce on the battery gauge.
 

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