Hi,
It has some recent discussion in the forum about battery warranty, chargers and etc. I just wish to provide some information here.
1) Phylion battery. We have decided to drop them completed following more problems with their quality consistancy in 2008 and 2009 which we have monitored closely.
2) Li+ polymer battery, we have been mostly using this battery since 2008.
The supplier is Advanced Electronics Energy Ltd. Which is the same supplier for Wisper and many other major ebike brands in Europe. However please note there is several choices for the BMS (Battery management system), after the first few batches in early 2008, we have specified for the BMS with O2micro the most advance microprocessor for power management, this balance the cells continuously vs simple hardware that just balance the cells during charging. We pay about GBP 5 more for this. I don't think the battery packs in Wisper have this, but I stand to be corrected.
3) In the recent cases about old HP chargers having problems with our new 14Ah battery, it might be a problem with compatibility of the BMS, sometimes these very sophisticated chips and programs happens to find a bug when they get engaged with older system. This is guess work, because we are unable to get our hands on the problem charger and battery, and we could not duplicate this problems on the bench.
4) We provide 4 amps fast charger with the 14 Ah battery.
5) We have now 2 other options for batteries :-
5.1) Li+ 18650 cells from Samsung. The pack still holds 37V10Ah From the tests data and expert advise we sought, we find this cells to better than even the best Japanese cells from Sanyo, better life span , better capacity at high discharge rates, wider operation temperatures.The price is slightly lower than Sanyo, but it will retail maybe GBP 80 more than the LiPo from Advance. We are supplying these to Canada where they ask for continous discharge of 20 amps ( we have tested these to be good even at 25 amps continous and at 48V = 1200 watts )
5.2) LiFePO4, with the cathode material from Phostech Canada. The cells are made in China. Most other LiFePO4 cells from China use cheap knock-offs cloned cathode material. However because of the cell size it would fit only the new battery casing for the rear carrier.
6) Warranty. First, we have to understand what we measure for the battery capacity. Battery capacity in Ah needs to be qualified with the discharge rate. Battery suppliers normally states the discharge rates in at 0.1C, which simply means is the cell is rated at 10Ah @0.1C, the measurement is done with a discharge rate at 1 amp. Battery capacity reduces at higher discharge rates, so the same battery at 2C or 20 amps one might get only 7Ah. Then please note this is the spec for A SINGLE CELL, when you have a pack of 10 cells, the actual capacity is reduced due to resistance for the 10 cells placed in series. So a 37V10Ah nominal pack would actually yield about 9.5 Ah discharge at 0.5C or 5 amps. And of course there is the factor of temperatures and etc. This should be done at ambient temp. of 20~25C
Our distributors are required to have test equipment to do discharge of the battery at 0.5C or 5 amps. Our warranty is for 70 % of original capacity within 12 months, and that works out to 9.5 x 0.7 = 6.65 Ah
ebikes brands using the same cells with basic simple BMS could be brave enough to give 2 years warranty (sometimes without defining what the warranty is based on) or their magins are big enough for the risks involved, just like insurance you take a big premium to cover the risks.
Given our experience, we like to be more conservative.
Yours truly,
Chief eZee Operator
It has some recent discussion in the forum about battery warranty, chargers and etc. I just wish to provide some information here.
1) Phylion battery. We have decided to drop them completed following more problems with their quality consistancy in 2008 and 2009 which we have monitored closely.
2) Li+ polymer battery, we have been mostly using this battery since 2008.
The supplier is Advanced Electronics Energy Ltd. Which is the same supplier for Wisper and many other major ebike brands in Europe. However please note there is several choices for the BMS (Battery management system), after the first few batches in early 2008, we have specified for the BMS with O2micro the most advance microprocessor for power management, this balance the cells continuously vs simple hardware that just balance the cells during charging. We pay about GBP 5 more for this. I don't think the battery packs in Wisper have this, but I stand to be corrected.
3) In the recent cases about old HP chargers having problems with our new 14Ah battery, it might be a problem with compatibility of the BMS, sometimes these very sophisticated chips and programs happens to find a bug when they get engaged with older system. This is guess work, because we are unable to get our hands on the problem charger and battery, and we could not duplicate this problems on the bench.
4) We provide 4 amps fast charger with the 14 Ah battery.
5) We have now 2 other options for batteries :-
5.1) Li+ 18650 cells from Samsung. The pack still holds 37V10Ah From the tests data and expert advise we sought, we find this cells to better than even the best Japanese cells from Sanyo, better life span , better capacity at high discharge rates, wider operation temperatures.The price is slightly lower than Sanyo, but it will retail maybe GBP 80 more than the LiPo from Advance. We are supplying these to Canada where they ask for continous discharge of 20 amps ( we have tested these to be good even at 25 amps continous and at 48V = 1200 watts )
5.2) LiFePO4, with the cathode material from Phostech Canada. The cells are made in China. Most other LiFePO4 cells from China use cheap knock-offs cloned cathode material. However because of the cell size it would fit only the new battery casing for the rear carrier.
6) Warranty. First, we have to understand what we measure for the battery capacity. Battery capacity in Ah needs to be qualified with the discharge rate. Battery suppliers normally states the discharge rates in at 0.1C, which simply means is the cell is rated at 10Ah @0.1C, the measurement is done with a discharge rate at 1 amp. Battery capacity reduces at higher discharge rates, so the same battery at 2C or 20 amps one might get only 7Ah. Then please note this is the spec for A SINGLE CELL, when you have a pack of 10 cells, the actual capacity is reduced due to resistance for the 10 cells placed in series. So a 37V10Ah nominal pack would actually yield about 9.5 Ah discharge at 0.5C or 5 amps. And of course there is the factor of temperatures and etc. This should be done at ambient temp. of 20~25C
Our distributors are required to have test equipment to do discharge of the battery at 0.5C or 5 amps. Our warranty is for 70 % of original capacity within 12 months, and that works out to 9.5 x 0.7 = 6.65 Ah
ebikes brands using the same cells with basic simple BMS could be brave enough to give 2 years warranty (sometimes without defining what the warranty is based on) or their magins are big enough for the risks involved, just like insurance you take a big premium to cover the risks.
Given our experience, we like to be more conservative.
Yours truly,
Chief eZee Operator
hn
