wgt40w

SOLVED PROBLEM As mentioned in one of my Threads above, I received the new adjustable charger. On first switching on the charger output was set at 50.8 volts. The charger has an external pot which I reset for an output voltage of 54 volts. I connected this charger to my battery and switched on - immediately indication showed it was charging. I immediately switched off the new 54volt charger. Immediately I connected the standard OEM charger (50volt) and instantly it indicated over to red light, i.e. charging. Remember, previously it was not showing the Red charging condition. Research now tells me that for the future I should not let the 48 volt battery get below (a safe) 45 volts before charging. So, I have saved myself the unnecessary cost of a new battery (approx. £200), by only spending a delivered price of £50.74. Furthermore the new charger not only has an external adjustable voltage output, it can also be set to charge in 2 or 3 stages. I may well re-adjust the output voltage to 50.8 volts and use it as my default charger in 3 stage mode, which means it ends by trickle charging.

Update: Instead of taking apart one of my standard 48volt chargers, I have orderd one of these adjustable output voltage chargers. Link to Adjustable Output Charger

Nealh & Andy-Mat Thanks for your comments, but neither of you make any suggestions as to what I should/ could do. I have checked my newest multimeter against mains voltage - here showing 249 volts. My bike/ battery is only about 9 months old. It has spent far more thime discharging 'naturally' than through being ued powering the bike. Having looked at a video elsewhere - it was suggested I should connect a charger with a higher output voltage (around 55 volts) - leaving it only connected for a few seconds until the charging light changes to red. Then disconnect and re-connect the 'proper' charger. Unless you suggest anything else, this is what I propose to do. If all else fails I suppose I will just have to buy a new battery (circa £200).

Nealh - many thanks for your detailed reply. I do not argue with anything you say, but two aspects surprised me. 1) On my e-bikes 'digital dash display' the state of the battery charge is shown as 5 or 6 segments of a circle. The current 39.9 volts state is shown as two of the segments 'full'. I would never have previously imagined that at this state the battery was so discharged it will not charge up. 2) At one stage I suspected my charger might be at fault and bought another one. The output specifications of both say 54.6v, but my multimeter shows both outputting at 50volts dc. Would you suggest I try taking one of them apart to see if there is a pot I can adjust to 54.6v - OR would you suggest I buy a 'better' charger (both mine Samebike chargers but slightly different models) PS In the past I have emailed CTEK, the manufacturers of well-respected car battery conditioning chargers, and suggested they should bring out versions for e-bikes. No reply ever received.

During the winter I am not using my e-bike much. However, I do keep an eye on the battery and have never let it even nearly fully discharge. Currently my 48v battery is showing it is at 39.9 volts and I have decided to charge it back up. I have checked my charger with a multi-meter and it is outputting exactly 50.0 volts. My problem is that when I connect my charger, the charger indicator light only momentarily changes from default unconnected green to 'charging' red - then back to green - i.e. it is not charging the battery, even after being left on for 1 hour. I have read elsewhere about batteries 'going to sleep'. Could this really have happened to me with a 48 volt battery when it has 39.9 volts in it?? If it has 'gone to sleep', how does one 'wake' a 48 volt battery???