LiFePO4 in a 905se
- Thread starter winterdog
- Start date
Can’t you get a new battery from Wisper themselves – they seem to be quoting super powerfully batteries - Li(NiMnCo)O2 …. What ever that is?
The Wisper web site quotes three battery sizes, which one is yours?
36V 14Ah 504Wh
36V 8Ah 288Wh
25V 8Ah 200Wh
Can’t seem to find any prices on the Wisper Web Site, so you will probably have to ask them direct.
I presume your battery is either dead or dieing and is five or more years old? The Whisper site is claiming 5-year-old batteries will not get the same range as when the battery was charged for the first time. If it's younger I should take the issue up with them and see what they say.
Not sure if you could get a LiFePO4 Battery Pack of the right Ah or physical size to fit an original Wisper battery pack - 14Ah is a big battery.
Or are you thinking of putting it in your panniers?
The best place I can think of to get a special size LiFePO4 Battery Pack would be Ping in China. That’s where I got mine last year.
Results for 36V LiFePO4 Battery Packs
Ping Prices (Mar09)
36V 10AH LiFePO4 Battery Pack
Small Size: 150x105x140 mm / 5.9x4.1x5.5 inches
PRICE: $289.00
36V 15AH LiFePO4 Battery Pack
Small Size: 225x105x140 mm / 8.9x4.1x5.5 inches
PRICE: $385.00
36V 20AH LiFePO4 Battery Pack
Small Size: 300x105x140 mm / 11.8x4.1x5.5 inches
PRICE: $470.00
If it's any help, I fitted a LiFePO4 Battery in my Cougar MTB style bike. Details can be found on the thread below of how I went about it (not a Wisper bike). Frank9755 also fitted a LiFePO4 Battery on his Wisper bike at the same time (he posts on the thread) his went in his panniers.
http://www.pedelecs.co.uk/forum/electric-bicycles/1741-dilemma-replacing-my-sla-batteries.html
----------------------------------
Cougar Mountain Electric Bike (Jul07)
fitted with LiFePo4 battery (Apr08)
.
The Wisper web site quotes three battery sizes, which one is yours?
36V 14Ah 504Wh
36V 8Ah 288Wh
25V 8Ah 200Wh
Can’t seem to find any prices on the Wisper Web Site, so you will probably have to ask them direct.
I presume your battery is either dead or dieing and is five or more years old? The Whisper site is claiming 5-year-old batteries will not get the same range as when the battery was charged for the first time. If it's younger I should take the issue up with them and see what they say.
Not sure if you could get a LiFePO4 Battery Pack of the right Ah or physical size to fit an original Wisper battery pack - 14Ah is a big battery.
Or are you thinking of putting it in your panniers?
The best place I can think of to get a special size LiFePO4 Battery Pack would be Ping in China. That’s where I got mine last year.
Results for 36V LiFePO4 Battery Packs
Ping Prices (Mar09)
36V 10AH LiFePO4 Battery Pack
Small Size: 150x105x140 mm / 5.9x4.1x5.5 inches
PRICE: $289.00
36V 15AH LiFePO4 Battery Pack
Small Size: 225x105x140 mm / 8.9x4.1x5.5 inches
PRICE: $385.00
36V 20AH LiFePO4 Battery Pack
Small Size: 300x105x140 mm / 11.8x4.1x5.5 inches
PRICE: $470.00
If it's any help, I fitted a LiFePO4 Battery in my Cougar MTB style bike. Details can be found on the thread below of how I went about it (not a Wisper bike). Frank9755 also fitted a LiFePO4 Battery on his Wisper bike at the same time (he posts on the thread) his went in his panniers.
http://www.pedelecs.co.uk/forum/electric-bicycles/1741-dilemma-replacing-my-sla-batteries.html
----------------------------------
Cougar Mountain Electric Bike (Jul07)
fitted with LiFePo4 battery (Apr08)
.
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I have to say, 5 years sounds very optimistic 
But here's the actual part quote from the site:
Battery age. As batteries get older they start to lose the ability to hold a charge for as long as they did when they were new. If you are using a 5 year old battery you will not get the same range as when the battery was charged for the first time.
Wisper Bikes
Although, it doesn’t actually say the battery will last any given time.
Time will tell, as always.
Well, as Mr Spock said when he got his first ebike on Vulcan (a reddish Minshara-Class planet orbiting the star 40 Eridani A).
"May your battery live long and may your piggy bank prosper"
.
But here's the actual part quote from the site:
Battery age. As batteries get older they start to lose the ability to hold a charge for as long as they did when they were new. If you are using a 5 year old battery you will not get the same range as when the battery was charged for the first time.
Wisper Bikes
Although, it doesn’t actually say the battery will last any given time.
Time will tell, as always.
Well, as Mr Spock said when he got his first ebike on Vulcan (a reddish Minshara-Class planet orbiting the star 40 Eridani A).
"May your battery live long and may your piggy bank prosper"
.
It was shown on Virgin 1 a couple of weeks back.ps. rule 168 is intresting
From Star Trek Deep Space Nine Season 7 Episode 6, Treachery, Faith and the Great River.
Ferengi Rules of Acquisition #168 "Whisper your way to success"
There are some that claim Star Trek has had a profound influence on them and changed their lives for the better.
For those who have watched it, and the repeats (I actually watched the repeats of the repeats) it’s clear that there's some logic in these claims. I'm not just talking about the fanatics here.
Each short episode has something to say. Morals come through thick and fast on every story about professionalism, parenting, race, religion, culture and even sexuality.
Laugh at it if you will, but there is no other television programme that's run so long and has these character challenging morals at its core.
Of course, if things get too bad there's always the option to either "Beam out" or "Shoot to kill"
.
For those who have watched it, and the repeats (I actually watched the repeats of the repeats) it’s clear that there's some logic in these claims. I'm not just talking about the fanatics here.
Each short episode has something to say. Morals come through thick and fast on every story about professionalism, parenting, race, religion, culture and even sexuality.
Laugh at it if you will, but there is no other television programme that's run so long and has these character challenging morals at its core.
Of course, if things get too bad there's always the option to either "Beam out" or "Shoot to kill"
.
I've been considering this as a replacement for my battery when it eventually dies (hopefully not for another year or so!).
The answer is it's not so simple!
Basically on first sight it looks like replacing the battery with a LiFePO4 would be a no-brainer. They are cheaper to buy ATM, and claim lifetimes of many cycles certainly much more than the "official" Li(NiMnCo)O2 can theoretically deliver.
However, there's a catch..... it's known as C rate, or put simply how much current the battery can deliver. Ping LIFEPO4s (arguably the best known) are generally regarded as 1-2C batteries i.e. they can deliver 1-2 x the AH rating as continuous current so for a 10AH that's 1-2x10=10-20amps, for a 15aH thats 1-2x15 = 15 - 30amps.
We don't know the C rating for an official Wisper battery but it's likely to be at least 10C if not much much more given its chemistry!
My Wisper controller (may not be the same for later controllers) is rated at 18Amps. So at first glance the Ping even at 10Ah should be fine.
However, when a battery is pushing out a large proportion of its C rating the voltage it produces "sags", so for example the 10Ah ping kicking out 20Ah (2C) might sag 5 or 6 volts, perhaps enough to cause the controller to cut out!
The official Wisper battery, with its much higher C rating probably won't sag much at all. So it's likely it'd give a much perkier performance than the Ping, with less cutouts on hills.
You might try to counteract this by a) Using a very large ping e.g. the 20Ah (to be recommended for other reasons) or by b) Overvolting i.e. using a slightly higher voltage Ping (custom built) to counteract the sag in the first place (if your controller can take it)
And then you've got the problems of size and mounting, the 20AH pings are much bigger and heavier than their 14AH Wisper equivalents....
So you see that's it's not quite as trivial as it might first appear. That's not to say that it can't or shouldn't be done, just that you should not expect it to be as simple and pain free as buying the official battery! (on the other hand it might be, we'd need to know the full specs of the Wisper battery to compare)
I'd love to hear from anyone that's done it!
I'd also really love to know the full specs on the official Wisper battery, but I can understand why those might not be forthcoming
Cheers
Steve
The technical points you make are probably valid. To be honest I'm not an electrician and don't understand all the complexities. What I do know is this C value has been tested and discussed (at great length) on Endless Sphere, which I read prior to changing my battery from start to finish. The conclusions were clear - a Ping battery was not suitable for ebikes that had an Ah of 30Ah or higher. As long as this is understood they are fine. The one's that did cutout were on the American users ebikes with 500w/1000w motors at 48v and above. Some of these were drawing 40/50Ah. Just from reading it was evident that these users were pushing the batteries to their limits and beyond, which is why they were cutting out. It was a bit pathetic because they were actually causing their own problems and then blaming the batteries - bit silly really.
Logically, if one has a Wisper ebike with an aged battery then it makes sense to buy an official Wisper battery to replace it. But it seems not everyone is so convinced that only an official Wisper battery will do. Likewise there are owners of other ebikes who have had to resolve spares problems from alternative sources.
I myself didn't have a choice. My 8-month-old e bike was no longer available so a replacement battery was not an option. Having already spent £500 on an ebike that I liked, I was not in the mood to start all over again.
My 36v Cougar Mountain Electric bike is rated to 25Ah and this was taken into account when Ping made my battery. The proof is in the “pudding” as they say. The battery is now almost 12 months old and has never cut out under load, except when at it maximum range and gone flat.
Despite everyone quoting these magical C values all the time, as far as I know no other forum members, who have fitted these Ping batteries (including Wisper owners - to ebikes rated below 30Ah), have had any cut out problems.
So a LiFePO4 Battery Pack is a very viable and workable replacement option
----------------------------------
Cougar Mountain Electric Bike (Jul07)
fitted with LiFePo4 battery (Apr08)
.
Logically, if one has a Wisper ebike with an aged battery then it makes sense to buy an official Wisper battery to replace it. But it seems not everyone is so convinced that only an official Wisper battery will do. Likewise there are owners of other ebikes who have had to resolve spares problems from alternative sources.
I myself didn't have a choice. My 8-month-old e bike was no longer available so a replacement battery was not an option. Having already spent £500 on an ebike that I liked, I was not in the mood to start all over again.
My 36v Cougar Mountain Electric bike is rated to 25Ah and this was taken into account when Ping made my battery. The proof is in the “pudding” as they say. The battery is now almost 12 months old and has never cut out under load, except when at it maximum range and gone flat.
Despite everyone quoting these magical C values all the time, as far as I know no other forum members, who have fitted these Ping batteries (including Wisper owners - to ebikes rated below 30Ah), have had any cut out problems.
So a LiFePO4 Battery Pack is a very viable and workable replacement option
----------------------------------
Cougar Mountain Electric Bike (Jul07)
fitted with LiFePo4 battery (Apr08)
.
The technical points you make are probably valid. To be honest I'm not an electrician and don't understand all the complexities. What I do know is this C value has been tested and discussed (at great length) on Endless Sphere, which I read prior to changing my battery from start to finish. The conclusions were clear - a Ping battery was not suitable for ebikes that had an Ah of 30Ah or higher. As long as this is understood they are fine. The one's that did cutout were on the American users ebikes with 500w/1000w motors at 48v and above. Some of these were drawing 40/50Ah. Just from reading it was evident that these users were pushing the batteries to their limits and beyond, which is why they were cutting out. It was a bit pathetic because they were actually causing their own problems and then blaming the batteries - bit silly really.
Logically, if one has a Wisper ebike with an aged battery then it makes sense to buy an official Wisper battery to replace it. But it seems not everyone is so convinced that only an official Wisper battery will do. Likewise there are owners of other ebikes who have had to resolve spares problems from alternative sources.
I myself didn't have a choice. My 8-month-old e bike was no longer available so a replacement battery was not an option. Having already spent £500 on an ebike that I liked, I was not in the mood to start all over again.
My 36v Cougar Mountain Electric bike is rated to 25Ah and this was taken into account when Ping made my battery. The proof is in the “pudding” as they say. The battery is now almost 12 months old and has never cut out under load, except when at it maximum range and gone flat.
Despite everyone quoting these magical C values all the time, as far as I know no other forum members, who have fitted these Ping batteries (including Wisper owners - to ebikes rated below 30Ah), have had any cut out problems.
So a LiFePO4 Battery Pack is a very viable and workable replacement option
----------------------------------
Cougar Mountain Electric Bike (Jul07)
fitted with LiFePo4 battery (Apr08)
.
Footie, that's good to know.
The effects of the lower C value are more likely to be:
a) Earlier cutting out on hills when the battery is getting near empty *compared to a higher C battery.
b) Less ooomph and acceleration *compared to a higher C battery.
However, from what you say these theoretical effects are not noticeable on your 36V25A bike, which is great news as my Wisper is only 36V18A. Which size Ping are you using?
Personally I think that the Ping batteries look like a very viable option as a replacement for e-bike batteries. I'm certainly still considering one myself to save a good chunk of money (and coz I like fiddling with things
)!(we also have a discussion on ES regarding mixing battery types in order to counter the effects above. For instance maybe you could put the ping in parallel with a "toolpack" battery.).
Cheers
Steve
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Ping’s batteries went through a hard time prior to my purchase and his BMS were cutting out as said before. The high voltages were also frying them. Mine was a new type of BMS, which he brought in and he was forced to set limits, they have been good ever since. Because I wanted my battery to fit within the original SLA case mine was a special slim line 10Ah. It was compromise of size over performance. I know a lot of ebikers now go for the 15Ah replacement and put it in their panniers, giving them a similar if not better result. When ordering from Ping it’s important to tell Ping the fuse rating of your ebike as this is crucial for the BMS.
I have thought about adding another battery but at the moment I’m happy with it as it is.
----------------------------------
Cougar Mountain Electric Bike (Jul07)
fitted with LiFePo4 battery (Apr08)
.
I have thought about adding another battery but at the moment I’m happy with it as it is.
----------------------------------
Cougar Mountain Electric Bike (Jul07)
fitted with LiFePo4 battery (Apr08)
.
Last edited:
Using a battery at more than the recommended C rating can severely impact upon it's life.
Just going to add a bit here. The Wisper has a 14AH battery. Discharging at 1C (14A) will empty it in an hour. A Ping v2.5 should be fine at 2C continuously, and 3C as a peak. For a 36V15Ah battery that's 36*15*2=1080W. I highly doubt the Wisper could draw that much if it tried, and you might peanut butter the gears inside the motor if you did.
If you're worried about C ratings the answer is to get the biggest Ping battery you can, or buy the more expensive higher rated cells. A waste on anything less than an e motorbike or a specialized offroad hotrod IMO.
Just going to add a bit here. The Wisper has a 14AH battery. Discharging at 1C (14A) will empty it in an hour. A Ping v2.5 should be fine at 2C continuously, and 3C as a peak. For a 36V15Ah battery that's 36*15*2=1080W. I highly doubt the Wisper could draw that much if it tried, and you might peanut butter the gears inside the motor if you did.
If you're worried about C ratings the answer is to get the biggest Ping battery you can, or buy the more expensive higher rated cells. A waste on anything less than an e motorbike or a specialized offroad hotrod IMO.
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