Well I dropped off there !
I should have listened to the advice on here about buying individual cells and a BMS instead.
I thought I'd post on here as a warning to anyone like me that was tempted to buy a motorbike style 12v lithium Lifepo4 battery for deep cycle use. A 6 month old one came up on ebay for a very good price, £80, compared to the UK new price of around £250.
I'd suckered myself in with the spec of 2kg weight with 12v 27ah.
I then thought that as lithium ion ebike batteries can be discharged down to 20% capacity, that would give me around 22ah use per charge. I was quite wrong though, because the "27ah" was "PbEq" rating, which means the "same as" an equivalent rated lead acid battery, so the damn thing only has 9ah cells internally.
Shorai then recommend that they be discharged by no more than 50%, so I'm only going to get 4.5ah per cycle.
Their forte seems to be the cold cranking ability with motorbike engines, coupled with very light weight, long life, and minimal self discharge when left standing and disconnected. So quite useless for ebike application, or my intended use with an electric outboard. (It's going straight back onto Ebay !)
Here's a cut and paste from Shorai's answer on an faq page:
Shorai batteries are rating for starting purposes. If you draw power on one like a deep cycle battery, you‘ll find about 1/3 of the capacity. Therefore, the 18AH battery would have the perceived capacity of a 6 AH battery. We recommend not discharging a battery more than 50%, so that translates to 1 hour of safe runtime for the 18 AH Shorai battery under a 3 amp load.
Shorai batteries are designed to be charged similarly to the lead acid counterparts. Using a charging system with a regulator should be fine. It may not be preferred, and the life span of the battery may not reach the full 7 years, but it will work.
taken from http://www.batterystuff.com/kb/frequently-asked-questions/powersports-batteries-faq/lithium-iron-faq.html
So the moral is, don't be fooled by "PbEq" ratings !!
I should have listened to the advice on here about buying individual cells and a BMS instead.
I thought I'd post on here as a warning to anyone like me that was tempted to buy a motorbike style 12v lithium Lifepo4 battery for deep cycle use. A 6 month old one came up on ebay for a very good price, £80, compared to the UK new price of around £250.
I'd suckered myself in with the spec of 2kg weight with 12v 27ah.
I then thought that as lithium ion ebike batteries can be discharged down to 20% capacity, that would give me around 22ah use per charge. I was quite wrong though, because the "27ah" was "PbEq" rating, which means the "same as" an equivalent rated lead acid battery, so the damn thing only has 9ah cells internally.
Shorai then recommend that they be discharged by no more than 50%, so I'm only going to get 4.5ah per cycle.
Their forte seems to be the cold cranking ability with motorbike engines, coupled with very light weight, long life, and minimal self discharge when left standing and disconnected. So quite useless for ebike application, or my intended use with an electric outboard. (It's going straight back onto Ebay !)
Here's a cut and paste from Shorai's answer on an faq page:
Shorai batteries are rating for starting purposes. If you draw power on one like a deep cycle battery, you‘ll find about 1/3 of the capacity. Therefore, the 18AH battery would have the perceived capacity of a 6 AH battery. We recommend not discharging a battery more than 50%, so that translates to 1 hour of safe runtime for the 18 AH Shorai battery under a 3 amp load.
Shorai batteries are designed to be charged similarly to the lead acid counterparts. Using a charging system with a regulator should be fine. It may not be preferred, and the life span of the battery may not reach the full 7 years, but it will work.
taken from http://www.batterystuff.com/kb/frequently-asked-questions/powersports-batteries-faq/lithium-iron-faq.html
So the moral is, don't be fooled by "PbEq" ratings !!
