Electric Bikes - NiCad Question
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01-11-09, 04:07 PM
Hi. I'm new to eBiking and I think I already messed up.
Bought a Crystalite kit last April. I charged the battery fully. Before using it for the first time in September I charged it again. I rode maybe 10 km twice with charging in between (back in September). The battery was good. I don't know if I charged it after the second ride. Now I'm trying to use the bike and it doesn't hold any charge. What's worse, it won't let me charge the battery much.
I can charge the NiCad for 5 minutes before the charger says the batter is fully charged. Then I can only ride a couple minutes before the battery is discharged again.
I've since learned that this is what happens with NiCads that are neglected. I tried searching for references on this forum but couldn't find any threads. I'd like to read up on NiCads (w.r.t eBiking) and perhaps the best way to recover the battery to full health if possible(w/out spending any more $).
01-11-09, 04:07 PM
Oh yes, and I did first search the forums before posting this. But I think I lack the specific language to retrieve and fruitful results :(.
01-12-09, 02:25 PM
... bump ...
This morning I rode to work with the battery "fully" charged. Before the ride the charge indicating LED on the throttle said "HIGH". As soon as I applied throttle I didn't get the normal sound and feeling (as if a subway car accelerating). Also the LED changed to "LOW". As soon as I released the throttle the LED read out "HIGH" again. But the system has no power. I bet when I get home later today I will only be able to charge the battery for a couple minutes before the charger computes the battery is fully charged.
By the way I still rode the whole 10 km to work with the throttle down and at the end when I got off the bike I could get the motor to spin the wheel for a couple seconds before the throttle LED indicated "LOW" and the motor died for a couple seconds.
Is this indicative of a NiCad battery issue? How can I remedy if so? Am I making things worse?
01-12-09, 03:14 PM
It sounds like you have a damaged battery. You should never store any battery flat. I use NiCads and the only time they've messed up is when they overheated, and a cell blew. You might check your pack, to see if one has expanded.
Some people claim they can bring back bad cells, but I've never seen it. I bike 42 kms a day and charge the cells twice a day. It's lasted over a year, but the real secret is that I pack it in ice in the summer. Twice I've blown up cells when they over-heated and once the cell exploded like a gun!
01-12-09, 05:01 PM
When I get home I will remove the foil from the pack and inspect the cells.
01-13-09, 11:45 AM
Just in case anyone ever searches the forums because their NiCad only holds 30 seconds of charge and they cannot charge it past a couple minutes. Drain the NiCad completely.
I guess all of the symptoms I described in my posts above are symptoms of a neglected battery.
Yesterday I rode to work and back (20 km) with full throttle applied. There was no noticeable assist, but I was draining the battery. I was able to charge it for a good couple hours (maybe 3) in the evening. This is the first time in a couple cycles.
This morning I rode to work (10km) and had assist all the way in. No weirdness with the throttle LEDs or lack of power.
Hi...did you discharge your pack below the low-voltage cutoff? My 48V Nicad pack has no LVC control in the pack, unlike a lithium battery pack, so I need to use the CycleAnalyst from ebikes.ca to set a low voltage cutoff in the controller. Ebikes.ca recommended 41 volts for a 48 volt pack, and it will scale back the current, as the voltage drops to this level, to hold the pack voltage around a minimum of 41 volts. If Nicads are discharged too low, you can get cell reversals and damaged cells I understand. I'm not sure of the LVC setting for a 36 volt pack. Otherwise, Nicads are pretty robust.
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