I own a BL-36 with an extended battery pack (12 Volt DC, 12 Amp Hour Lead-Acid Gel-Cell Batteries (x3) = (36 Volts 12 amps). After almost a year, I had a significant decrease in range. In the beginning, on an average run (couple low hills, stop and go's at traffic signals, riding half the way into head winds) I got about 17-18 miles. Now I get about 8-10 miles at a fast speed. I figured the batteries are used up and I need a fresh SLA battery pack.
I got as a gift from a family member 3 - SLA batteries rated at 12 volts 18 amps (36 volts 18amps), I wired them up exactly like the original battery pack. My question is, after I wired up the batteries and I plugged in the charger, after 5 minutes I can hear a faint bubbling noise and/or a fizzing noise coming from the new batteries. After about 30 minutes of charging, I can still hear the faint bubbling noise however, all 3 batteries and the wire harness are cool to the touch, and the charging box is warm to the touch (about the same temp as it was when charging up the old battery pack). The charger has the automatic shut off / trickle charge feature built in.
I did some research online about someone else with the same concern: a couple replies to the post said if a loud bubbling is heard it's possible that the batteries are over-charging. The last reply said that a faint bubbling noise on new SLA batteries are normal for the first couple days of recharging. Anybody have similar experiences like this? Any ideas on this subject would be helpful, thank you.