Help from a local Wisper owner

[pl1974]

Hi,

A while ago I posted a thread about the lack of power/range of my Wisper 905SE battery. Generally the response on here was that it seemed to be getting tired. As I'm still within warranty, around 16 months old I went back to Wisper.

After much correspndance, Wisper have tested the battery and found nothing worng with it so have returned it to me.

I still think the battery is low on power, most noticeably after say 10 miles or so it has a definite feeling of less power than when fully charged and the lights on the handlebars quickly go to one light under power.

So, I'm at a bit of a stalemate, I do still have about 8 months of warranty left and Wisper have said that if their tests show less than 70% capacity in that period they will replace.

So to the point of the thread.. I wondered if there are any Wisper 905 owners local to Rutland, I be really interested to compare the performance of my bike with yours.

Thanks,

Paul

 

[eddieo]

Is there a way of testing the percentage of power left, to see where abouts you are in relation to their 70% rule?

the lights on the handle bars mean little......they always die under load and then recover.

 

[tillson]

So, I'm at a bit of a stalemate, I do still have about 8 months of warranty left and Wisper have said that if their tests show less than 70% capacity in that period they will replace.

Or alternatively.

I have no idea how you test the battery for capacity without access dedicated test equipment. This is a very difficult area when it comes to warranty claims, made all the more problematic if there is inconsistancy about what is being guaranteed.

 

[Mussels]

I'm nowhere near unfortunately, good luck.

 

[pl1974]

Thanks for the replies and for the link tillson.

Its a really odd one as I think the Wisper test is based on voltage tests when fully charged and at various intervals during discharge. I still think my problem is 'sag' when under load.

Still not sure if I'm being over sensitive though, I'm sure there is a psychological effect of the handlebar lights in though they can't be relied on, but its also noticeable that the power drops off compared to fully charged.

Maybe I'll just keep riding for a while and see what happens..

Paul

 

[flecc]

The lights dropping more rapidly under load is perfectly normal as a lithium battery ages, even after one year, and at 16 months I'd expect it to be fairly obvious. Over time that will get more and more obvious, as will the range shortening.

Also the performance does fall away over time, since the cells gradually suffer from increased internal resistance with age, meaning it gets more and more difficult for current to flow out fast enough to meet demand. There comes a day in this process when the voltage drops so low under high load, as in climbing, that the battery's safety cutout operates and it stops on the hill. Switching off and back on resets it then, but if you throw the same load at it, it cuts out again. That's how you know it's new battery time.

I think you should just carry on using it. I've often remarked in here that the best thing owners can do with handlebar meters is to put a strip of black PVC tape over the lights and stop worrying!
.

 

[tillson]

There comes a day in this process when the voltage drops so low under high load, as in climbing, that the battery's safety cutout operates and it stops on the hill. Switching off and back on resets it then, but if you throw the same load at it, it cuts out again. That's how you know it's new battery time.

I have wondered what the deciding factor, which makes me buy a new battery, will be. It will be a financially painful day when it arrives.

I think you should just carry on using it. I've often remarked in here that the best thing owners can do with handlebar meters is to put a strip of black PVC tape over the lights and stop worrying!
.

That's very good advice.

 

[pl1974]

Thanks you're probably right. Think I'm a bit worried about the first signs of a failing battery after my experience with my Powabyke X6 battery and the company renaming itself and not honouring warranties.

Very interested in [thread=6399]this[/thread], it seems to discuss the same problem and suggets running the battery totally flat.

Paul

 

[flecc]

That's unlikely to help on a battery of that age Paul. In general once a lithium battery is run in it's best to avoid fully discharging, frequently part charging instead.

All rechargeable cells are stressed most at the extremes of charge, the last 20% of discharging and the top 10% of charging pushing the chemistry hardest. Batteries used in some special applications where long life is vital are run in the central charge region between 20% and 80% of charge and they last much longer. The Toyota Prius NiMh batteries are run like that and are guaranteed for 8 years. In satellites, lithium batteries only have one seventh of their content used before recharging once every 24 hours, and they easily last ten years (over 3500 charges).
.

 

[tenderbehind]

905 Battery

Hi Paul, I'm not very technical or mechanically minded but I'd like to help. I have a 905se, very pleased with it, I once measured, via a bike computer the complete range of the bike and this was 32 miles mainly on the flat and mainly throttle only but with some pedal assist on the slight inclines, the battery was then completley dead, this about 6 months after having bought the bike and having covered around 600 miles in total.
I have now had the bike about 2 years and a thousand miles approx, and although I have not taken another range measurement feel the machine and it's battery would still be able to achieve a similar performance.
I personally think that after 10 miles or so the battery might well ''slow down'' a bit, as it were; one third of the range gone and one light, the top green, goes out, I would think that about normal, the bike then hasn't quite got that initial 10 mile approx urgency or speed about it, but still quite quick, even on the last (red) light - still powerful enough on this last light to be of great assistance on the flat and when climbing inclines, I can feel the motor pulling quite strongly. I would think you have a reasonably performing battery there. (Of course I may be quite wrong!) Tony.

 

[pl1974]

Thanks Tony, do you mind me asking the rider weight

Only managed 8 or 9 miles this weekend, but all done on pedal assist.

Flecc, would you say that the same issue as the handlebar lights applies to the lights on the battery itself. After completing the above, the battery lights were showing only two out of four. However, later last night when I put the bike away I looked again and it was up to three. I understand batteries do recover a bit when resting.

A half full battery (see how I worded that..) isn't great after 8 miles. Although I do find it just keeps going and going when on the last light albeit with significantly less power.

Paul

 

[NRG]

Don't trust the handlebar LEDs they are notorious for being inaccurate. You should perform at leat one full charge, full discharge, full charge cycle to set the BMS 'fuel gauge'.

Discharge until the motor will no longer turn on power.

 

[eddieo]

the lights on the battery are more reliable then handlebar ones. and mine can recover one LED if left to rest as well say from 2 to 3? It can take ages to get these last two LEDs out, I know this having just completed 2 full discharges on a new battery.......it takes forever!


I wonder from what you say have you conditioned your batteries properly?

did you fully charge - run till completely flat - times 2 - when you first got it?

 

[flecc]

Yes, the LEDs dropping under power affects the handlebar meter more, but of course the battery ones can't be watched when under way!

The Giant Lafree bikes and Heinzmann kits get it right, they have no handlebar indications of battery level to worry anyone, so their owners are never fretting about this.

Power does fall away continuously as the battery level drops and this becomes more noticeable as the battery ages due to increasing cell internal resistance. This is unavoidable, and the last stages of battery content produce markedly less power. In the last stages before low voltage cutout it can be difficult to detect if there is any power at all.
.

 

[pl1974]

Thanks. Eddio, I did do a couple of deep discharges when I first got it, one of the really odd things is that when I did that, there was a definite low voltage cut out. For some time after this I didn't flatten the battery, only recently have I done this when checking the range and now there is no PVC, it just seems to fade away.

Still wondering if it's worth that full discharge, as I've certainly never run it out completely with the wheel in the air. Just wonder if it will do more harm than good?

Paul

 

[flecc]

Just wonder if it will do more harm than good?

Paul

It will on a battery that's already been run in and used for a while. Indeed completely emptying a battery by discharging it off the bike destroys it
.

 

[pl1974]

ok maybe not - Thanks Tony.

Paul

 

[tenderbehind]

Weight for it!

Hi Paul, Sorry, haven't been on the site since the 31st of August so didn't see your request for my weight! And I'm not really sure, I know I'm a bit overweight, at 5' 6'' tall I think I'm about 13 and a half stone. Hope this helps, Tony.

 

[pl1974]

Thanks Tony.

Your range seems quite low to me for your weight. I'm getting about 38 miles although that's on 80% pedal assist mode (15st). My biggest frustration is the noticeable drop in power after around 10 miles.

Wisper advertise a range of 56 - 74 miles. Guess there are a lot of variables though.

Paul

 

[Wisper Bikes]

Hi Paul

Range does so much depend on the amount of power a rider is demanding from the motor, with a throttle that works independently from the pedelec system (a system that so many people demand) a bike will rarely deliver the range of a bike that has a torque sensor only.

We do our range testing in NZ, tests are always undertaken by the same man Anthony Clyde who is a little over 12 stones. Anthony regularly achieves over 100KM (62 miles) from the set up you have, but never uses the throttle on these tests. Our new 15.4Ah batteries for 2011 are achieving a predictable 15% more range.

Flecc is right, try to ignore the handle bar readings, we too have considered removing them. I am sure your bike will still achieve a very similar range to when you first bought it although you will certainly start to feel the power lessen with age.

Rest assured that if we have tested it the battery is fine, however it may be worth popping it back to us just before the 24 month warranty to check that is is within the parameters we warrant. If it does not meet with our specifications we will certainly give you a new one.

All the best

David