Hi, everyone -- I hope you can help me with a problem I'm having my eBike.
On Friday of last week, my battery on my bike suddenly started to drain at a very rapid rate.
My commute is 6.5 miles, with a moderately steep uphill grade at each end of it each direction (picture a U, with my house at one top and my office at the other). Before last Friday, I could get to that hill on with 90% battery remaining (green light), then be showing 80%-60% remaining by the top (green/yellow) or 60% (yellow) on a bad day.
Suddenly - and it was suddenly - this was not a gradual decline - I'm lucky to be at half charge by the time I get to the hill, and today, I actually had to walk the last part of the hill, being at less than 5% charge. It gets progressively worse daily.
My pedaling habits have not changed - I'm always pedaling, and use the motor for a slight assist. My charging pattern has not changed. It gets about an hour and a half (enough to charge the battery full) when I get home, then a full eight hours overnight so it's ready to go in the morning.
The battery is less than a month old, and was sold to me by this guy, who seems to sell a lot of eBike stuff.
Any ideas??
yeah I got some ideas, ironically
sla: so easy to wear them out, best used only for walmart shopping carts: a bit too hot, overdischarged, not recharged right away, not a good brand or in good condition to begin with, charger not working right...plenty of reasons, too many reasons not enough time.
yellow lights: that means you have overdischarged the battery if its sla. the lights mean nothing in relation to an accurate picture of battery state and when the sla curve has fallen off a cliff. once you get a red light...well the battery has totally crapped out before you can get a red light, so you won't ever get a red light! smart technology eh?
fix: ditch sla and invest in some real batteries. 36v 15ah lifepo. 36v20ah lipo. 36v13ah nimh. 48v16ah lipo. get my drift? get a wossup or analyst. the 36v bike is awesome, it deserves it!
It certainly could be a bad battery, but it could be other things as well. First thing you want to do is load test the battery. Charge it up full and then, er, here's where my level of knowledge runs out. I have never come up with a way to do it I really liked that didn't involve expensive machines, but I'm sure it can be done. You could repost the battery part of the question in the batteries part of the forum. Make sure to note the type and specifications. At the end of this you should know that either the charger or the battery is bad, with the battery being the more likely of the two.
There could also be a drain on the battery in the bike. If you have an ammeter and know how to use it you could look for a larger than usual parasitic drain on the battery as it sits in the bike.
Lastly, how much does that 6.5 miles to work draw your battery down? If you are consistently using 80% to 90% of the battery this is a bad thing. Some batteries will die faster than others if they are treated this way, but deep cycling is death for all SLA batteries.
"we must be the change we wish to see in the world"
There may be only one battery that couldn't hack it. On my bike, yellow light was more like 90% drained, but I did it more times than you and my batteries are still fine, so you do have a problem. One often overlooked one is undercharging. One kook posted that his batteries were fully charged after 2 hours on a 2 amp charger. Try 6 to 10 hours dude. Leaving them hooked up instead of turning it off when the light turns green will help with some chargers.
The first thing you need is a cheapie voltmeter, usually ten bucks or so at hardware and auto parts stores. I would start by running the bike home from work, and then checking the voltage of each battery individually to see if one is very much lower than the others. Then charge all three, and check voltage individually again, and again after they have sit overnight. The one that was low to start with, or low in the morning is the bad one. If they all lose a bunch overnight then you may have a poor battery for an ebike. Not all 12v sla's are made for a motor, so if he sold you computer power back up ones they will go bad fast.
Options, forget warranty unless you like a good fight.
Replace with good sla's such as B&B's that are made for ev's
Replace with other chemistry batteries. Lifepo4 really is nice for me, and a good size Ping battery from ebay is actually cheaper in the long run than lead. This is the only way to go if you like the ebike enough to commit to 5 or more years of riding. You need to get the 20 ah size on the Ping batteries to get a decent amperage out of it without damage. So that option seems pricy, at around 5-700 bucks but a good set of B&B's is about half that anyway. And even with the B&B's you may be too close to using all the capacity every day to get max cycles out of a lead battery.
Be the pack leader.
36 volt sla schwinn beach cruiser
36 volt lifepo4 mongoose mtb
24 volt sla + nicad EV Global