HDJ81 Stock Dual Battery Questions (1 Viewer)
- Thread starter podiev
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Not any more than any of the other electrical loads like headlights or the fan blower, since the two main fusible links come off of one battery and run most of the electrical items in the vehicle. When operating under normal conditions (vehicle running or stopped, electrical system in 12V form) the two batteries are linked in parallel and essentially are one massive battery and the load is shared between the two, charging and discharging equally. Thats why in a jump start situation it is only necessary to hook one of the batteries to a charger or another vehicle, since they will both charge at the same time until the key is turned to the 'start' position.
Dave 2000
Not all Land Rovers are useless!
I would have to have a closer look, the reason I say that is the fusible links as you say run from one battery, but not from the changeover switch. It has been so many years since I converted mine to 12 volt starting now I cannot remember, but didn't the main charge cable from the alternator run across the cooling fan cowling to the changeover switch or other battery, then it was able to charge both batteries? If this was the case then why not run it direct to the nearest battery?
Bare with me I am getting old and forgetful.
Regards
Dave
If you connect any accessories to the USDS battery +ve and chassis earth or any other vehicle earth then the accessory will see 24 volts during starting.
Both batteries are connected to chassis ground during normal operation. The USPS battery directly to the chassis and the USDS via the S2A-S2C contacts of the 12/24 Relay.
Both batteries are charged together. You can connect loads to the UDSD battery but you must source the ground from the battery -ve terminal to avoid the 24V spike during starting. ¨ Not sure why you would bother though.
The factory did not go to all the trouble to print and fit that label and cover for no reason.
For jump starting i connect to the USPS with jumper leads and wait a while to allow both of the casualty vehicle batteries to absorb some charge before attempting to start the vehicle.
Both batteries are connected to chassis ground during normal operation. The USPS battery directly to the chassis and the USDS via the S2A-S2C contacts of the 12/24 Relay.
Both batteries are charged together. You can connect loads to the UDSD battery but you must source the ground from the battery -ve terminal to avoid the 24V spike during starting. ¨ Not sure why you would bother though.
The factory did not go to all the trouble to print and fit that label and cover for no reason.
For jump starting i connect to the USPS with jumper leads and wait a while to allow both of the casualty vehicle batteries to absorb some charge before attempting to start the vehicle.
I just confirmed this is correct with the memory function on my Fluke volt meter. Fortunately most 12V stuff can also do 24V, just need to check before leaving it plugged in while starting!
Dave 2000
Not all Land Rovers are useless!
Just to make it clear about my setup.
When driving the two batteries are connected together, so 12 volts.
Switching off the engine and the two batteries remain connected together for a number of hours or days depending on draw for example, with just the alarm set the batteries will remain connected together so the 'draw' of the alarm is shared by the two batteries, eventually depending on time and temperature the Blue Seas VSR will disconnect the batteries, so now the right hand battery is taking the load, the left hand battery remains with a healthy charge to start the engine.
When I start the engine the load is taken by the left hand battery, only after the engine has been running a few minutes the VSR joins the batteries are now in parallel and both are now being charged, and this is how my 80 has been setup for years. The only variation I would mention is the time taken for the VSR to part the batteries, if the fridge is on (all accessories are connected to the right hand battery except the NL battery monitor) then the batteries will be disconnected from each other earlier, it is not unusual for the batteries to disconnect and then reconnect once the fridge has gone off once down to temperature during the early few hours of the fridge being on, this is because the right hand battery voltage has recovered so the VSR reconnected them to each other.
I can never go off road without a fridge due to keeping my insulin cool, so imperative that all is good, the VSR allows me to connect the batteries together at anytime to be able to jump start the engine from either battery if one fails.
Regards
Dave
When driving the two batteries are connected together, so 12 volts.
Switching off the engine and the two batteries remain connected together for a number of hours or days depending on draw for example, with just the alarm set the batteries will remain connected together so the 'draw' of the alarm is shared by the two batteries, eventually depending on time and temperature the Blue Seas VSR will disconnect the batteries, so now the right hand battery is taking the load, the left hand battery remains with a healthy charge to start the engine.
When I start the engine the load is taken by the left hand battery, only after the engine has been running a few minutes the VSR joins the batteries are now in parallel and both are now being charged, and this is how my 80 has been setup for years. The only variation I would mention is the time taken for the VSR to part the batteries, if the fridge is on (all accessories are connected to the right hand battery except the NL battery monitor) then the batteries will be disconnected from each other earlier, it is not unusual for the batteries to disconnect and then reconnect once the fridge has gone off once down to temperature during the early few hours of the fridge being on, this is because the right hand battery voltage has recovered so the VSR reconnected them to each other.
I can never go off road without a fridge due to keeping my insulin cool, so imperative that all is good, the VSR allows me to connect the batteries together at anytime to be able to jump start the engine from either battery if one fails.
Regards
Dave
Isn’t the chassis ground issue only found when on the port side battery with the warning covers?
I am looking to hook up a redarc BCDC using one positive wire from the drivers side of RHD model, then using the chassis ground local to the BCDC and inverter; behind the seat. Is this the way to go?
I believe that is correct, I would have to check on my brother's HDJ81 as I can't remember which battery is which. Just make sure to pull power off the ground-side battery and you will be fine. What kind of amperage does the Redarc pull?
output current 25A
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