I have a 2007 VX-1 with only 3150 miles on the clock, but the range is now down to about 15 miles max. from a full charge, if I use the bike and top up the charge without fully discharging the battery I end up with even less range.
I found the only way I can achieve a reasonable range is by running it down until the battery light comes on, which resets the battery gauge and then allows a full charge to be taken. The last time I needed to use the bike for a longer trip I left it on charge overnight after being completely drained until the light came on the previous day. I noticed in the morning that the battery temperature was very high when I came to use it, but thought no more about it.
Today I went to use the bike which has been stood for a couple of weeks and the battery voltage was only reading 126V, even though the gauge showed the battery as being well over half full, so I decided to run it until the battery light came on and then monitor the charge process. I managed to just limp home after travelling less than a mile in total, and with the battery light on for the last 1/4 mile.
I put it on charge and took several readings as it was charging at different time intervals.
After about 40 minutes I noticed that the voltage had strangely dropped from 142V to 141V and did not alter over the next 40 minutes. I also noticed the temperature reading seemed to be stuck at 19°C as well, even though the battery capacity gauge was still filling up. At this point I switched if off at the mains and then switched it back on again to resume charging again, and the voltage had jumped from 141V to 145V, and the temperature had also jumped from 19°C to 24°C.
I continued to monitor the readings and noticed that the temperature began to increase quite quickly when the battery voltage reached 148V.
Within the 16 minutes it took to increase from 148V to 150V, the temperature had risen from 31°C to 40°C and I noticed that the battery light had also started flashing.
So after a total of 1 hour and 51 minutes I stopped the charge with just 11 bars filled out of the 17 on the battery gauge.
I put it straight back on the maximum delayed charge (8 hours 45 minutes) to allow the cooling fans to cool down the battery pack.
The fans eventually cut out and after four hours the battery temperature is now down to 24°C and the voltage is currently reading 138V with 12 bars showing on the battery gauge.
I have plotted a graph from the readings I recorded, but I had to delete the readings taken between 40 minutes and 1 hour 20 minutes when the voltage and temperature readout had frozen, because they upset the graph:
I presume the overheating is the result of several faulty cells (probably shorted out) which means the charger it is trying to overcharge the remaining good cells to achieve the set target voltage (153V).
I'm guessing I probably have at least four or five completely dead cells for it to start overheating at 148V, and it looks like I will be pulling my battery pack apart in the near future to hopefully find out for sure.
Has anyone else had a similar experience regarding the overheating problem and/or the frozen voltage and temperature readings?
I have also experienced some very unusual voltage readings in the past whilst charging which can be seen in this video clip.
Assuming it is just a few faulty cells, I am now looking at the following two options:
- Find some second hand NiMh cells that are still usable and repair my existing pack
- Find a supply of Leaf cells (18 modules) and replace the entire pack
I would ultimately like to perform a leaf cell conversion, but I think I may have to go for the poor man's option of simply replacing the faulty cells (assuming I can locate some suitable replacements) in order to keep the bike running for a little bit longer until I can afford to buy some of those lovely leaf cells.
In which case, does anyone in the UK have some usable NiMh cells that they no longer require? (ideally in the South West area)
If I can't find any NiMh cells, I might have to consider removing (or bypassing) 11 of the NiMh cells (including the faulty ones) and make up a 30Ah 4S6P LiPo pack to put in series with the Vectrix pack to provide the required pack voltage.
EDIT: Picture link repaired