I've been looking for a dual battery solution with less complexity than most I've been seeing. I haven't seen anyone discuss this particular option, so I'd like to throw this out for public scorn. At first glance, it seems like it may be a very simple and effective solution.
Here's the schematic:
The Blue Sea L-series LCR is a relay that closes when either high current terminal is at 13.4 volts or greater, i.e when the vehicle is charging. Otherwise, it is open. It sells for about $150 and is rated at 450+ amps, depending on wiring gauge used.
Without the control switch, the batteries would both be charged whenever the alternater was working. The second battery would be isolated if the alternator were not generating, so you could run the winch on the isolated second battery by shutting down the engine.
Adding the control switch lets you manually open or close the relay, or leave it in the automatic mode described above.
The manually open mode allows you to isolate the second battery and winch with the engine running.
The manually closed mode allows you to use the second battery for emergency starting, or use both batteries to get home without a working alternator.
Advantages are:
o minimized length of fat, high current wiring
o no required cutting into the stock wiring
o no need to pull an "alternator good" signal
o only one small relay required (about 2" x 2.5")
o very high amperage capabilities
o supports most use/charge combinations, except those listed below
o fewer points of failure
o comparatively cheap
Disadvantages are:
o Can't run winch ONLY off of battery #1 (it's both or #2)
o Can't charge ONLY battery #2 (it's both or #1)
I think these are fairly small inconveniences.
You could also add another battery switch between battery 2 and the winch if you want to disable the winch when you're not using it, but I prefer the total simplicity of what I've got drawn above.
Blue Sea makes a control switch for this, but you could use any switch that provides +12 for closed, ground for open, or floating for automatic mode. I'm not sure if any stock Landcruiser switches can be modified to provide these three conditions but I think it's likely. Any ideas on that one?
Note that I didn't show the ground connections, but for each componant you'd have to hit the closest appropriate ground.
I also showed the control switch being powered off of the relay terminal, but you could pick up +12 from any convenient location. The switch wire current is very low, so you can use a thin wire and put the switch anywhere you like.
Comments?
Here's the schematic:
The Blue Sea L-series LCR is a relay that closes when either high current terminal is at 13.4 volts or greater, i.e when the vehicle is charging. Otherwise, it is open. It sells for about $150 and is rated at 450+ amps, depending on wiring gauge used.
Without the control switch, the batteries would both be charged whenever the alternater was working. The second battery would be isolated if the alternator were not generating, so you could run the winch on the isolated second battery by shutting down the engine.
Adding the control switch lets you manually open or close the relay, or leave it in the automatic mode described above.
The manually open mode allows you to isolate the second battery and winch with the engine running.
The manually closed mode allows you to use the second battery for emergency starting, or use both batteries to get home without a working alternator.
Advantages are:
o minimized length of fat, high current wiring
o no required cutting into the stock wiring
o no need to pull an "alternator good" signal
o only one small relay required (about 2" x 2.5")
o very high amperage capabilities
o supports most use/charge combinations, except those listed below
o fewer points of failure
o comparatively cheap
Disadvantages are:
o Can't run winch ONLY off of battery #1 (it's both or #2)
o Can't charge ONLY battery #2 (it's both or #1)
I think these are fairly small inconveniences.
You could also add another battery switch between battery 2 and the winch if you want to disable the winch when you're not using it, but I prefer the total simplicity of what I've got drawn above.
Blue Sea makes a control switch for this, but you could use any switch that provides +12 for closed, ground for open, or floating for automatic mode. I'm not sure if any stock Landcruiser switches can be modified to provide these three conditions but I think it's likely. Any ideas on that one?
Note that I didn't show the ground connections, but for each componant you'd have to hit the closest appropriate ground.
I also showed the control switch being powered off of the relay terminal, but you could pick up +12 from any convenient location. The switch wire current is very low, so you can use a thin wire and put the switch anywhere you like.
Comments?
Last edited:
