D40 Dual battery setup
- Thread starter Arty_74
- Start date
Help Support Nissan Navara Forum:
Voltage drop can only be properly detected when there's a load on the line, so be careful about measuring it. Here's a real example.
I changed the setup with the new caravan. I took the 12V input to the fridge, plugged that into an Aldi 600W inverter, plugged the 240V plug from the fridge into that and with the engine idling, I turned on the fridge. I expected the fridge to draw somewhere between 300 and 400W - possibly a good 30A, which made it a fantastic test on the cabling, especially since it wasn't just the length of the car, but the same length again from the connection point at the front to the fridge itself.
What I discovered was that the 6mm cable used by the auto electrician that set up my car originally was far from effective when a large amount of power was drawn through it. 14.1V at the battery became 10.6V or something like that at the rear, the inverter started singing from low voltage and I turned the lot off. I then replaced the 6mm cable with the 8G cable I linked to and tested it again.
Voltage drop was now in the order of less than a volt over the entire length. The inverter works perfectly.
Operating the fridge like that works rather well, for those that are interested. On 12V, the heater is just barely maintained (it doesn't use the thermostat, it just runs at a low level the entire time) and if you open the fridge door while travelling, the 12V supply really can't bring the temp back to normal. The 240V circuit, on the other hand, operates through a thermostat - so it's not even on all the time - obviously running a little harder when it DOES run. Does it work? Oh yes. We started the trip at easter with the fridge temp higher than it should be, putting my assumptions on the line about the fridge's operation where it was most important - with our food! It worked - we arrived at Cassilis Park Rest Area where I stopped to check the fridge and it had brought the temps down perfectly.
So, to the question - is the cable I pointed to enough? Sure is!
I changed the setup with the new caravan. I took the 12V input to the fridge, plugged that into an Aldi 600W inverter, plugged the 240V plug from the fridge into that and with the engine idling, I turned on the fridge. I expected the fridge to draw somewhere between 300 and 400W - possibly a good 30A, which made it a fantastic test on the cabling, especially since it wasn't just the length of the car, but the same length again from the connection point at the front to the fridge itself.
What I discovered was that the 6mm cable used by the auto electrician that set up my car originally was far from effective when a large amount of power was drawn through it. 14.1V at the battery became 10.6V or something like that at the rear, the inverter started singing from low voltage and I turned the lot off. I then replaced the 6mm cable with the 8G cable I linked to and tested it again.
Voltage drop was now in the order of less than a volt over the entire length. The inverter works perfectly.
Operating the fridge like that works rather well, for those that are interested. On 12V, the heater is just barely maintained (it doesn't use the thermostat, it just runs at a low level the entire time) and if you open the fridge door while travelling, the 12V supply really can't bring the temp back to normal. The 240V circuit, on the other hand, operates through a thermostat - so it's not even on all the time - obviously running a little harder when it DOES run. Does it work? Oh yes. We started the trip at easter with the fridge temp higher than it should be, putting my assumptions on the line about the fridge's operation where it was most important - with our food! It worked - we arrived at Cassilis Park Rest Area where I stopped to check the fridge and it had brought the temps down perfectly.
So, to the question - is the cable I pointed to enough? Sure is!
