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11th June 2024, 09:05 AM
#1
Expert
dual batteries & dual voltage sensing relays
After adding a 190w panel to the roof and a Victron 75/15 smartsolar MPPT to specifically charge the Aux battery, I added a 2nd voltage sensing relay to help maintain the cranking battery when the patrol is parked in the sun for long periods.
So both batteries will connect to the other when their voltage is over 13.3v & disconnect when under 12.8v.
I'm in the process of running 8mm2 cable to the fridge to help minimize voltage drop when compressor is on.
I like it, all I need now is a decent aux battery
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11th June 2024 09:05 AM
# ADS
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11th June 2024, 01:42 PM
#2
Travelling Podologist
Sounding good, but I'd suggest that 8mm2 may be a bit light unless the fridge is pretty close to the battery. I would use a minimum of 8AWG which is 10mm2. Also if you are expecting cable induced voltage drop when you have the compressor running, do you have the compressor & fridge on the same circuit? If so I would advise a separate circuit for each.
I have just run two new circuits in our truck. One just for Starlink running direct of 12v (12v to 47v converter) from a circuit breaker rated at 16 amps, & the other to run an Engel freezer & my Cpap machine from a 10 amp circuit breaker. Both using 8AWG/8B&S cable.
I'm kinda hoping that you have used the same gauge cable & wrongly assumed it is 8mm2?
2006 4.2TDi ex-Telstra Remote area Camper. 425w roof mounted solar, 360Ah Aux batts, BCDC1240, Onboard hot & cold pressurised & filtered water, (25 litre hot water calorifier), ARB fridge, ARB freezer, Built in kitchen, heaps of easy access storage, 240v, 3 Genie exhaust + dynotune, 2 lift, 3900kg GVM upgrade, second glovebox, ROH Blaktrak steel wheels, Bridgestone D697's (now Toyo RT's), Redarc gauges/pillarpod, Hema HX-1, Icom 450 CB, dual rear view cameras, Onboard 30amp Victron mains charger, second glovebox, dual seat conversion, TPMS, Boss PX7 onboard air with 9 litre tank, 350w inverter, Steel bullbar, Harrop Eaton diff lock (front), Warn winch, Snorkel, Dual spares , 160 litre water tank, 180 litre fuel in two tanks (approx 1200km range) 2010 Tvan Tanami. (incl another 70 litre water tank) with matching wheels/tyres (& 3rd spare)
A Nomadic Life (Blog)
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12th June 2024, 09:13 AM
#3
Expert
Originally Posted by
Cuppa
Sounding good, but I'd suggest that 8mm2 may be a bit light unless the fridge is pretty close to the battery. I would use a minimum of 8AWG which is 10mm2. Also if you are expecting cable induced voltage drop when you have the compressor running, do you have the compressor & fridge on the same circuit? If so I would advise a separate circuit for each.
I have just run two new circuits in our truck. One just for Starlink running direct of 12v (12v to 47v converter) from a circuit breaker rated at 16 amps, & the other to run an Engel freezer & my Cpap machine from a 10 amp circuit breaker. Both using 8AWG/8B&S cable.
I'm kinda hoping that you have used the same gauge cable & wrongly assumed it is 8mm2?
sorry by compressor I meant the one in the fridge.
I used to have a 3rd battery in the back right next to the fridge with a separate dc-dc charger but used that battery in another project and now want to simplify things in the car and just stick with the two under the bonnet.
I've already bought the 8AWG cable so if I have issues I'll have to either double it up or get bigger stuff
Last edited by pollenface; 12th June 2024 at 09:34 AM.
2008 CRD Auto Wagon
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12th June 2024, 01:18 PM
#4
Travelling Podologist
Originally Posted by
pollenface
sorry by compressor I meant the one in the fridge.
I used to have a 3rd battery in the back right next to the fridge with a separate dc-dc charger but used that battery in another project and now want to simplify things in the car and just stick with the two under the bonnet.
I've already bought the 8AWG cable so if I have issues I'll have to either double it up or get bigger stuff
Ah my mistake re compressor. Doh!
If it's 8AWG & not 8mm2 it'll be fine.
2006 4.2TDi ex-Telstra Remote area Camper. 425w roof mounted solar, 360Ah Aux batts, BCDC1240, Onboard hot & cold pressurised & filtered water, (25 litre hot water calorifier), ARB fridge, ARB freezer, Built in kitchen, heaps of easy access storage, 240v, 3 Genie exhaust + dynotune, 2 lift, 3900kg GVM upgrade, second glovebox, ROH Blaktrak steel wheels, Bridgestone D697's (now Toyo RT's), Redarc gauges/pillarpod, Hema HX-1, Icom 450 CB, dual rear view cameras, Onboard 30amp Victron mains charger, second glovebox, dual seat conversion, TPMS, Boss PX7 onboard air with 9 litre tank, 350w inverter, Steel bullbar, Harrop Eaton diff lock (front), Warn winch, Snorkel, Dual spares , 160 litre water tank, 180 litre fuel in two tanks (approx 1200km range) 2010 Tvan Tanami. (incl another 70 litre water tank) with matching wheels/tyres (& 3rd spare)
A Nomadic Life (Blog)
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15th June 2024, 09:39 PM
#5
Expert
Originally Posted by
Cuppa
Ah my mistake re compressor. Doh!
If it's 8AWG & not 8mm2 it'll be fine.
apparently 8awg is 8.3mm2, 7awg is 10.5mm2
https://www.rapidtables.com/calc/wire/awg-to-mm.html
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16th June 2024, 09:45 AM
#6
Travelling Podologist
Originally Posted by
pollenface
Hmmmm, I may have got it wrong based upon this…. https://www.multicable.com/resources...ce-awg-to-mm2/
2006 4.2TDi ex-Telstra Remote area Camper. 425w roof mounted solar, 360Ah Aux batts, BCDC1240, Onboard hot & cold pressurised & filtered water, (25 litre hot water calorifier), ARB fridge, ARB freezer, Built in kitchen, heaps of easy access storage, 240v, 3 Genie exhaust + dynotune, 2 lift, 3900kg GVM upgrade, second glovebox, ROH Blaktrak steel wheels, Bridgestone D697's (now Toyo RT's), Redarc gauges/pillarpod, Hema HX-1, Icom 450 CB, dual rear view cameras, Onboard 30amp Victron mains charger, second glovebox, dual seat conversion, TPMS, Boss PX7 onboard air with 9 litre tank, 350w inverter, Steel bullbar, Harrop Eaton diff lock (front), Warn winch, Snorkel, Dual spares , 160 litre water tank, 180 litre fuel in two tanks (approx 1200km range) 2010 Tvan Tanami. (incl another 70 litre water tank) with matching wheels/tyres (& 3rd spare)
A Nomadic Life (Blog)
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17th June 2024, 09:16 AM
#7
Expert
Originally Posted by
Cuppa
There is a lot of confusion and mis-use with wire gauges and sizes. According to the old standard, 8 SWG is 12.97 mm2, 8 AWG (also B&S) is 8.36 mm2. There is also 8 BWG (not common now) 14.79 mm2.
The only way to be absolutely sure what you have is to measure and count strands and calculate the total cross sectional area.
Then there is the 'automotive' way of referring to size by 3mm, 4mm etc which doesn't appear to directly relate to either wire diameter, copper diameter or cross sectional area.
The best way to purchase electrical wire is to go by copper cross sectional area only and ignore all the rest.
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The Following 5 Users Say Thank You to Brissieboy For This Useful Post:
BrazilianY60 (20th June 2024), Cuppa (18th June 2024), Hodge (17th June 2024), PeeBee (17th June 2024), Winnie (20th June 2024)
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20th June 2024, 09:27 AM
#8
Expert
I've got a voltage drop calculator on my phone which shows AWG/B&S and mm2 ... so i understand that at least
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