Electric Bikes - Lawn Tractor Batteries
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I bought by EVGlobal 36v sx in 2004, used it for a year and then covered it up in the garage until last weekend. I'm getting it back on the road.
I was at walmart an noticed 12v lawn tractor batteries 180ccc. I know that if I run them in series I can get the 36v I need . . . but are they worth buying. They are $19 each. I don't want to spend $$$$$ for batteries and I would rather keep it simple. How would I calculate Ahr?
03-29-13, 09:25 AM
Usually those 12v battery are around 9ah and weight around 10 pounds if you connect 3 of them them in series you get 36v 9ah 324w more speed less miles,if you do parallel 12v 27ah 324w.
Watts = Amps x Volts
ah=amps x hour
consider the EVGlobal motor wattage,if its 500w,the batterys are only putting out a little more than half of what you need and 30pounds worth of weight plus there sla and have a lifespan of about 300 to 600 charges.
check this site
Thanks for the information and the link . . . it was an interesting read.
I never thought of battery usage in that manner. The stock EVGlobal 36v battery was 8amp (if memory serves), therefore it would have been "underpowered" from the beginning. So using 20 watt hr per 1.6 km . . . the 324w should get me around 26km using the power unsparingly.
When I was using the bike for work commute I only used power for a couple of long hills and if there was a headwind around the late. It also helped when starting from a stop light. As the commute was 40 km round trip, and I would get two trips before I needed charging . . . I must have been conserving power.
My stock 36v battery was about 30lbs . . . but it was placed lower on the frame than where the lawn tractor batteries would go. therefore changing the center of gravity. Hmmmm.
Sooo . . . I'm thinking that the three lawn tractor SLA may be an option.
03-29-13, 11:50 PM
While the lawn tractor batteries seem like a good price, see if they are of the SLA or Sealed lead acid, because
if they are of the normal wet type cell, there would be a good chance of them leaking acid through the vents
as you go over bumps, or if you do not have them level most of the time.
The common ones I have used are the SLA types that are used in alarm systems and UPS's etc.
These types are safer to use I believe. I had 3 12volt 11 ah ones when I first started ebikeing in 2008,
then just renewed them this winter to some 14 ah ones to use on a tricycle conversion for the winter months.
I went a bit higher ah rating because of the losses you get in the cold.
I got mine from this site shipped free, http://saskbattery.com/ecommerce_010.htm
I got good range because I do pedal almost all the time, and use the assist to do just that, assist.
We have an Interstate battery here locally (NL) however the options are limited for 6v and 12v batteries.
I found BatteryBuyer.com . . . more batteries but the shipping is bad.
Saskbattery have a good selection of 6v and 12v batteries, good pricing and FREE shipping. Excellent !
Now I have to figure out if my 36v charger is working and check how much space I have for batteries.
I would like to do http://www.endless-sphere.com/forums/viewtopic.php?f=2&t=7309&start=0&st=0&sk=t&sd=a if the charger is working.
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