3x12v 12ah battery life

[jeohearn]

Wndering how long I can expect 3x12v 12ah lead acid batteries to last me. My commute is 7 miles each way, one way is a very slight upgrade (in a car one would think it flat) with one small short hill. The throttle is down all of the way for 90% of the commute and I am pedalling almost the whole way. I make that commute 5 days per week and I charge once I get to work and then overnight at home -so two charges per day.
Thanks,
Jeff

 

[dogman dan]

I'd say a year at most, quite possibly less. Bear in mind I don't know the battery brand and model, but my meager experience with sla's was with ones that lasted a lot less than half a year. The key thing is going to be how discharged they get each cycle. If it's more than 80%, like on the uphill trip, then they will die fast. If you are using more like 60% then you may see more cycles. But 50 weeks x 5 days a week is 250 round trips, so 500 cycles a year. I seriously doubt you will see 500 cycles unless you are using only 50% of the battery capacity per cycle. 200-300 cycles is about the expected lifespan of sla's.

So invest in a good lithium pack that could go the whole distance both ways in one charge, Say a 48v 15 ah or 36v 20 ah. If you get 1000-2000 cycles out of it, that's 4 to 8 years of battery life.

My sla's were getting hammered with daily 100% discharges, and lasted less than 50 cycles.

 

[jeohearn]

And if I do get a lithium pack, how much longer will it last...if I get one with enough amp hours to get me there and back without charging?

 

[docnjoj]

Well, dogman has 5000 miles and my wife has 3 years and around 2000 miles on her Ping 36 volt 10 ah. We don't take any special care of the batteries; just charge 'em up after rides and keep the bikes either in a shed or in the house. I think Pings are a great value.
otherDoc

 

[morph999]

if I was going to get some SLA's, I'd get some B&B EB 20-12 . It's a 12v20ah battery designed for electric bikes. You can get them for about $53 a piece. The bigger capacity would mean that you'd use less per run and it'd probably last longer. I just don't see the point in getting 12ah batteries. I got 9ah batteries and they get me about 3 miles.

I'm buying thundersky lifepo4 cells next here in about 2 weeks. About $400 for a 38v20ah. The B&B 36v20ah should be about $150 plus shipping.

 

[gilnet]

you should factor in the weight and size of 12v 20ah,and make sure they are deep cycle if you go this route.don't know how much you would gain in run time.if you can dig up the money and are committed to your commute the lithium suggestions should be looked at.yrs of plug and play,lighter load sure beats adding more weight.and your lifespan w/sla's won't vastly improve with the added ah.you might also check out the Ni batts.Dogman has had good experience w/them(see his posts).They are lower wt.than sla's.and aren't as expensive as lithium.If this is your main transpo for work: lithium

 

[D-Man]

7 miles isn't that far. Depends on if you got deep pockets. My sla's are pretty much shot right now. Got a little over 5000 miles. I was doing around 13 miles. If I was going everyday, no doubt I'd want the lifepo4. The nickel batterys are such a "rip off" for what you get compared to lifepo4. I'd like to have the blue nimh batteries from batteryspace that knightmb used but those are $700 plus chargers for 48v. Insane! Even nicads from ebikes.ca will run close to $450 with shipping and charger for 48v.