Voltage sensitive relay for easy charging. Setting up a camper, boat, caravan or food truck?
I have just set up a campervan with 240v. I presumed that by purchasing a large Deep Cycle battery that I could get away with just one but found that
: Deep cycle batteries are not to be used for cranking your engine
: Deep cycle batteries must not be connected in parallel with your starting battery.
This threw a spanner in the works for me as it meant I had to charge the house battery via a mains powered charger or a solar panel. This seemed ridiculous as my truck had an alternator happily spinning around that had more than enough capacity to charge both batteries while driving!!!
A VSR (voltage sensitive relay)
They are simple to install (see diagram)
When the engine is started, the starting battery and auxiliary batteries are separated allowing only the starting battery to be charged. When the charge voltage reaches 13.3 volts the voltage sensitive relay (VSR) engages allowing both starting and auxiliary batteries to be charged. When the engine is stopped and the battery voltage falls below 12.8 volts the VSR disengages separating the start and auxiliary batteries.
The auxiliary battery continues to power any accessories without risk of draining the starting battery.
You will need appropriate wire and fuses to install.
I usually have 4000 w inverters in stock too if you need one.
• Continuous rating: 125A
• Voltage rating: 12VDC (max 15VDC)
• Cut in voltage: 13.3VDC
• Cut off voltage: 12.8V
• Isolator dimensions: 67(L) x 67(W) x 60(H)mm