Conditioning battery

[pl1974]

Conditioning wisper battery

Hi,

As you may know I recently bought a second hand Wisper. After a few teething problems I've got it working.

Managed to get out for a good run on it today, my big concern is how is the battery and I really needed to get 16miles (my commute) from it.

It just scraped 16 miles, but was hard going for the last couple of miles and required a fair amount of pedalling.

Anyway, I have a couple of questions:

1) Don't Wispers have a low voltage cut out to protect the cells?

2) Is there anything I can do to help condition the battery (balancing maybe?) to squeeze a few more miles out of it?


Thanks,

Paul

 

[flecc]

They do have a low voltage cutout, but I believe your problem is that the battery may be nearing the end of life, at or near two years old, so suffering loss of capacity. All the signs point to that, short range and lack of "oomph".(technical word )

Cell balance isn't normally a problem in lithium batteries since the internal battery management system (BMS) does this at every charge.

What make is your battery (Lishen?) and what capacity is it, 10Ah, 14Ah etc?
.

 

[pl1974]

Thanks Flecc. I thought the same thing really, but hoped there may be a trick to prolong the life a bit.

Its a Lishen 10ah

Paul

 

[flecc]

That's one of Wisper's previous types and quite old now. They've been using 14Ah ones for well over a year now on many of their bikes and quite a long time ago switched to the Advance company for their batteries.
.

 

[torrent99]

Hi,

As you may know I recently bought a second hand Wisper. After a few teething problems I've got it working.

Managed to get out for a good run on it today, my big concern is how is the battery and I really needed to get 16miles (my commute) from it.

It just scraped 16 miles, but was hard going for the last couple of miles and required a fair amount of pedalling.

Anyway, I have a couple of questions:

1) Don't Wispers have a low voltage cut out to protect the cells?

2) Is there anything I can do to help condition the battery (balancing maybe?) to squeeze a few more miles out of it?


Thanks,

Paul

1) Low voltage cutout (LVC)...... YES and NO.
NO... the BMS on the Lishen battery does not have a discharge BMS (i.e. it only does its work when you are charging the battery), so it does not monitor the voltage on each cell during use to ensure it doesn't go below the safe voltage.
YES... the controller has a 31.5V LVC for the input. So for perfectly balanced cells that's 3.15V per cell which is still quite a way above the typical lowest safe per cell voltage. So even if the cells were a bit out of balance, in practice it would be a problem.

2) There are a couple of things you could do.... but whilst it might save you money in the short term, it will cost you more in the long term (compared to buying a new big battery).
You could add another battery in parallel (see http://www.pedelecs.co.uk/forum/electric-bicycles/1261-torq-battery-mod-storms-up-hills.html). I'm considering a Bosch 36V Litheon "toolpack" battery for this method as it's the same chemistry as the Lishen cells. Of course many factors may mean this doesn't work how you'd like. (there's a growing thread on Endless Sphere discussing how to do this in a more generic way).

You could also add some voltage in series. I've just bought the parts to add 2.4-3V (i.e. 2x NiMH) in series. This will raise the voltage to the controller meaning that a) It's a little bit faster b) It takes longer to cut out. However, this is also not without it's problems.
1) You mustn't add too much or you might burn out your controller.
2) By adding voltage you are artificially "lowering" the LVC voltage for the main pack, which could mean that when the bike eventually cuts out some cells might be below the safe voltage. This isn't a problem for me as I definitely DON'T intend to run the pack this far (I like to have at least 2x the required range in batteries!).


In the end though you'll have to buy a new battery, sooner or later....
And if you are of a DIY bent, this is where the fun starts... (hints Ping, Dewalt, Bosch, Endless Sphere).
The big thing though when buying a battery is to get it bigger (25-50%?) than you think you need!

 

[rog_london]

You could add another battery in parallel (see http://www.pedelecs.co.uk/forum/electric-bicycles/1261-torq-battery-mod-storms-up-hills.html). I'm considering a Bosch 36V Litheon "toolpack" battery for this method as it's the same chemistry as the Lishen cells. Of course many factors may mean this doesn't work how you'd like. (there's a growing thread on Endless Sphere discussing how to do this in a more generic way).

You could also add some voltage in series. I've just bought the parts to add 2.4-3V (i.e. 2x NiMH) in series. This will raise the voltage to the controller meaning that a) It's a little bit faster b) It takes longer to cut out. However, this is also not without it's problems.
1) You mustn't add too much or you might burn out your controller.
2) By adding voltage you are artificially "lowering" the LVC voltage for the main pack, which could mean that when the bike eventually cuts out some cells might be below the safe voltage. This isn't a problem for me as I definitely DON'T intend to run the pack this far (I like to have at least 2x the required range in batteries!).


In the end though you'll have to buy a new battery, sooner or later....
And if you are of a DIY bent, this is where the fun starts... (hints Ping, Dewalt, Bosch, Endless Sphere).
The big thing though when buying a battery is to get it bigger (25-50%?) than you think you need!

If you add batteries in series to raise the overall voltage, there's quite a big snag which you can't avoid - the added cells will invariably have different capacities to the ones already there. If you run that combination to cut-out then it's more or less guaranteed that some cells will be driven WELL below their safe lower limit, and they could even find themselves being reverse-charged.

Either of these conditions is the kiss of death to any battery technology.

If you add batteries in parallel (with suitable diodes for most technologies - not required for SLAs) you would have a better arrangement, provided that they're the same technology, have the same cut-off voltage, and (if you use the same charger) that they have the same top-out voltage (this last would probably be a function of any BMS fitted). Different capacities between batteries will not matter at all, though.

Rog.

 

[pl1974]

Thanks for this, all sounds a bit complicated.

Anybody know how much the new 14ah batteries are from Wisper?

Paul

 

[torrent99]

Thanks for this, all sounds a bit complicated.

Anybody know how much the new 14ah batteries are from Wisper?

Paul

Roughly £500! Ouch. That's the falling pound I'm afraid!

You should be able to use an alternative battery from somewhere else, but then you have no guarantees about quality & you'll have to figure out how to mount it to the bike & connect it up.
Ping batteries come recommended by quite a few users, but they aren't for the faint of DIY!
A 36V battery from another bike builder e.g. eZee, Alien, Synergie etc, might also be a good alternative if they are cheaper and you can make them fit.
If you do go down the non-Wisper route, the bigger the better (last longer)!

 

[Wisper Bikes]

Battery replacement

Hi Rog

A new 36v 14a battery is £485 and a 36v 8a is £285, also don't forget we will give you £50 back for your old battery.

All the best David