I have just purchased Phoenix Smart Charger 1+1 version. For trickle charging the start battery, do I need to run wire for the minus also when main battery and start battery share the common minus? Or can I connect trickle minus to main battery minus?
(In previous charger there were only three cables for main and started battery)
The Victron schematic with the 1+1 charger show a negative connection for both the main charger and the trickle charger even though the batteries share a common negative.
VE-direct-drawing-with-Phoenix-charger-12-50-1-inverter-375W-MPPT-100-30.pdf (771.5 KB)
Yes, the diagram is clear and according to that I should have dedicated wire. In my case, running that trickle minus wire is quite some effort and I would like to avoid that if possible. Also it is not immediately obvious for me why it is needed.
The one reason is if the trickle charger is galvanically isolated from the main charger.
On the schematic you will note that the trickle charge negative does not go to the starter battery. If your main and starter batteries are connected by a common negative, then you can connect the trickle charger negative to anywhere, possibly even the negative terminal for the main battery on the charger.
If you have a multimeter check the resistance between the 2 negative terminal blocks. Do this with the probes in both directions in case there is a diode in there. If the resistance is zero or close to zero for both measurements then it can be ignored.