Batteries losing range quickly. Is it normal?

Joined
Jun 29, 2017
Messages
63
Hello all,

I have about 220 miles on my 48v 1kw bike. I have 4 12v 18ah deep discharge agm batteries in saddles on the sides of my rear tire. I travel about 12 miles back and forth to work every day. I am quite heavy with the throttle but I used to make it to work and back with 3 battery bars out of 4 left. I have been noticing this week that I have been making it home with 1-2 bars left and today going full throttle the low voltage cutoff started kicking in as my voltage was dipping down below 40v. Is this normal to start losing range at 220 miles? I charge it every single day when I get home to 100% and never discharge it more than half. I never leave it for more than a day uncharged. Is there a way to recondition the battery? I am getting lithium soon when I have the funds.
 


The_Aleman

Well-Known Member
Joined
May 2, 2007
Messages
1,046
You're most likely drawing too much continuous amperage for those batteries to handle. I don't know what the batteries you are using are rated for, discharge-wise but you might want to look at the fine print on em.

Deep-cycle batteries typically are for <1C continuous loads (under 18amps in your case), but they can handle 4-8 seconds of high load without cell damage. Rough calcs, 12v * 18a = 216w * 4 = 864. You have a 1KW system, you're drawing well over 1C. I'm no ebike or electric expert, but it would appear you are beating up your batteries.

If you turned down the power draw you'd prolly be okay. How much is the question!
 
Joined
Jun 29, 2017
Messages
63
You're most likely drawing too much continuous amperage for those batteries to handle. I don't know what the batteries you are using are rated for, discharge-wise but you might want to look at the fine print on em.

Deep-cycle batteries typically are for <1C continuous loads (under 18amps in your case), but they can handle 4-8 seconds of high load without cell damage. Rough calcs, 12v * 18a = 216w * 4 = 864. You have a 1KW system, you're drawing well over 1C. I'm no ebike or electric expert, but it would appear you are beating up your batteries.

If you turned down the power draw you'd prolly be okay. How much is the question!
I got in touch with someone from the company I ordered the batteries from and he said up to 180A for 5 seconds. Maybe they are starting to crystallize since sometimes I don't charge them for about 10 hours.
 
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