Strange Wisper battery behaviour

[pl1974]

Hi,

Been have a few problems with the Wisper for a while.

Originally I was just noticing less range, and also that the handlebar lights dropped quicker, for example immediately after a fresh charge the green light would go out under power on a slight hill when leaving my house. I was then realising it just felt like less power.

Anyway, recently when I changed my rear tyre I found some chafed wires from the motor.

Wisper were excllent and changed both the motor (with wheel) and speed controller.

I'd hoped this would cure the problem so set out to completely flatten the battery to check the range.

I've got to just over 30 miles, although I was on the re handlebar light (and last light on the battery) since just over 20. The really odd thing is that when I've run it this low before the motor would cut out - low voltage cut out I presume. This time it has just kept on going with less and less power, to the point now that it will only pull me along at 5mph on the flat.

I'm sure I'll go back to Norman soon (although he must be getting fed up with me by now), but just wondered what you thought?

Does the speed controller handle the LVC or is it built into the battery?

Thanks,

Paul

 

[alex_h]

how old is that battery? and how many recharge cycles did you do?

 

[pl1974]

Hi Alex,

Its around 14 months old - I guess between 50 -100 cycles

Paul

 

[alex_h]

it looks to me like the battery is getting on a bit. It is quite natural for all liyhium batteires to loose memory with time so I would say you can get another 6 months of it and buy a new one

regards

Alex

 

[NRG]

Yep, the battery is starting to age....

 

[onmebike]

I have to say, it sounds pretty ridiculous that a Wisper battery for what they cost, is on its way out after 14 months and less than 100 cycles? Thats worse performance than sla batteries and less economical than my motorbikes 54mpg.
What are the makers claims for these batteries?

 

[Straylight]

It actualy sounds to me like the new controler may not be fuctioning properly, as I'd have thought it would cut the power entirely before the battery got to the stage you're describing, via the lower voltage limit. I could be wrong, and I'm sure Norman will clarify, but as I understand it, both the controler and BMS have cutouts to protect the battery, but the controler should do it first.

BTW, if you're like me and use a lot of power whilst riding (low pedelec + derestricted throttle), a range of about 30miles seems about right. My battery has shown very little signs of degredation over the 18 months I've had my bike.

 

[Mussels]

I have to say, it sounds pretty ridiculous that a Wisper battery for what they cost, is on its way out after 14 months and less than 100 cycles? Thats worse performance than sla batteries and less economical than my motorbikes 54mpg.
What are the makers claims for these batteries?

When I sold my Wisper the battery was over 18 months old and had been through several hundred charges (mostly partial), I hadn't noticed any drop in performance.

 

[Vikki]

Likewise with my battery. 18 months old, run down to about 50% each day, five days a week. Done two 3 mile runs recently finding routes to take Prowler on. Still had juice left. That's about 380 charges (from 50% to full).

I'd say there's a problem too.

Vikki.

 

[eddieo]

My first wisper sold at approx 18 months old also had no noticeable drop in performance either...

 

[pl1974]

Thanks very much for your comments, looks like I'd better go back to Norm again.. Wispers have a two year warrnaty on the battery, to cover 70 or 80% capacity I think.

The bit that confuses me is whether its the battery or the controller that deals with the low voltage cut out. Wouldn't want to have a new battery and put it at risk without proper LVC

So do you notice a big power difference on a fully charged battery to one thats nearly flat. I find it will pull me along at 15mph (ahem..) fully charged, but drop down to quite a bit less after 15 -20 miles and as I wrote before 5mph after 30 miles..

Thanks,

Paul

 

[Vikki]

After 30 miles mine is still blasting along. No noticeable drop in power.

Vikki.

 

[onmebike]

Thanks very much for your comments, looks like I'd better go back to Norm again.. Wispers have a two year warrnaty on the battery, to cover 70 or 80% capacity I think.

The bit that confuses me is whether its the battery or the controller that deals with the low voltage cut out. Wouldn't want to have a new battery and put it at risk without proper LVC

So do you notice a big power difference on a fully charged battery to one thats nearly flat. I find it will pull me along at 15mph (ahem..) fully charged, but drop down to quite a bit less after 15 -20 miles and as I wrote before 5mph after 30 miles..

Thanks,

Paul

From what I understand from much reading, the bms monitors at cell level and cuts off if any cell drops below a preset voltage e.g. 3.1volts and the controller monitors total pack voltage and cuts at approx 31volts. These figures apply to a 36volt pack.