New member and ebike convert SLA replacement advice sought

[akathatman]

Hi,
My first foray into battery assisted cycling has begun this week with the purchase of a second hand Currie Electro-Drive kit of unknown vintage now installed in a basic MTB. This will I hope wean me off the car for those shorter journeys and give me some much needed exercise too.
I would welcome any advice on choosing 12V replacement SLA cyclic batteries, from posts I have read in the forum I understand the correct type should be Deep Cycle but some retailers also talk of Ultra Deep Cycle or Premium Grade...is there a measurable performance/longevity benefit between any of these or are they just marketing terms? Would there be any advantage or harm done by increasing the Ah from the original 12Ah?
Many thanks to all who have made this forum such a great resource.

 

[benjy_a]

I would just use a lithium ion rechargeable, you can use any capacity (Ah) you want it makes no difference other than how much charge it holds (i.e. the more Ah the more range you will have).

I just had a peak on eBay and 12v lithium is very cheap and much lighter and smaller than SLA.

Ben

 

[Blew it]

If I may add a little more to benjy_a's reply.

Deep cycle SLA's are usually listed as Valve Regulated Lead Acid (VRLA) or Amalgamated Glass Mat (AGM). Both types being suitable for electric bikes.

If you prefer high quality batteries such as Yuasa, then you need the ones with black writing, those with red writing are for UPS back-up systems and therefore not suitable for deep-cycle high discharge applications.

Ebay is a good source for Ritar brand deep cycle batteries, which should be good for around 250-300 charge/discharge cycles...good for two years use perhaps.

 

[flecc]

And you can increase the 12 Ah by any amount, the capacity increase has no ill effect other than weight and in fact can bring a very slight performance increase.

 

[akathatman]

Many thanks to all for the super quick replies and for pointing me in the right direction. I'm reluctant to pay significantly more for lithium over SLA although I do appreciate that it may be a better long term investment and offers some significant performance/weight/size advantages. For the moment and until the Currie motor setup proves itself adequate for the job and reliable (or not) I'll stay with AGM SLA's. The present way the battery case is mounted in the frame is fairly neat and well balanced. The most reasonably priced batteries which state specifically that they are suitable for powering electric vehicles would seem to be the Leoch LPC12-13 and Ritar RT120EV at just over £50 a pair on eBay, and if they last for more or less 2 years I'll be more than satisfied.