SORTED

[Charliefox]

Had the bike in a nice warm kitchen today. Worked fine on both batteries until........Sprayed the little conection box with WD40 to clear out any condensation from the very cold bike shed (-3C this morning) I hear a little sizzle and small sparking from the -ve lead from the battery. Back to low battery flashing LED. Removed both the junction blocks and found the -ve one partially melted. I would have soldered the power cables together with a double layer of heat shrink but could I find the solder paste? Solder would not stick to the wire ends. Then I found a ceramic junction box from a dismantled cooker (250V 10 Amp) which was fitted for the time being. All systems go. That melted junction box did last 5years and 6 months before failing though. There is no way the ceramic one will melt!

 

[Nealh]

Sound like the WD acted as a short between the contacts, one not to try again.

 

[matthewslack]

Good news!

I'd be interested to know the vital statistics of the huge looking rack mounted battery.

 

[Bikes4two]

Sound like the WD acted as a short between the contacts, one not to try again.

That's an interesting comment. Whilst I'd not consider WD40 as an insulator, neither had I considered that it'd be conductive either, and certainly not at the sort of voltages found around ebike batteries.

Mr Google gives different answers but the majority indicate that WD40 is OK to spray on contacts, typically in the automobile world.

If it warms up enough I might go down to the bike shed, spray some in a plastic jar lid and get my 500v insulation tester out.