Many years ago a friend named Mario, from Adventure Trailers, suggested I just use a giant battery and a low voltage disconnect instead of doing dual batteries on my 4runner. I’ve run this setup for the last 11 or so years with great success.
Briefly, when I bought the FZJ80 I let the previous owner’s dual battery system remain. The first large trip I did the system failed, and I was left with a dead battery. The batteries were Optima’s and could not be brought back to life. That did it for me, I purchased a large Odyssey Group 31 battery a new Battery Brain to exactly mimick the setup I had on my 4runner for 6 years and never looked back.
Over the years it’s saved me countless times. Getting home from a business trip at the airport to find that my fridge is still cold, but the battery had run low and thankfully disconnected sometime earlier that day. Listening to music at camp and forgetting to shut everything off before going to bed. Etc etc.
It cuts off the connection at a relatively high point so there is a good margin of safety to restart your vehicle. Just make sure you buy the correct one! (Diesel’s and some specialty vehicles take a LOT more juice to start so they need to have the proper voltage cutoff)
A couple weeks ago the Battery Brain cut off the battery while we were camping for 3 days in the same spot. I hadn’t yet run the truck knowing I have the battery brain and a microstart if that failed. On the second day it tripped off. The battery brain would NOT reconnect though. This is the first time in all these years I’d had a failure, but thankfully they plan for this by being able to push in and turn the reset button to “manually” reconnect the vehicle. I reset it and ran the truck for a while. Problem solved. It was time to replace the brain. It seems the technology has improved and the Priority start has better reviews so I’m trying this new style.
I’ll update on how it works!
*Footnote: Although I put all positive leads for the truck and accessories on the Priority start, I did put the winch and alternator directly to the battery to allow these to have the most direct connection possible. Since you should always have the truck running while winching I don’t foresee it being a problem and I’ve always set these up in this way.
Battery Comparison-
Optima Yellow Top for my truck:
Performance Data | |
| Cold Cranking Amps: | 620 |
| Cranking Amps: | 770 |
| Nominal Voltage: | 12 volts |
| Open Circuit Voltage (fully charged): | 13.1 volts |
| Internal Resistance (fully charged): | 0.003 ohms |
| Capacity: | 48 Ah (C/20) |
| Reserve Capacity: | BCI: 98 minutes (25 amp discharge, 80°F (26.7°C), to 10.5 volts cut-off) |
Odyssey/Enersys/Diehard Platinum Group 31 Battery:
| SPECIFICATIONS | |
|---|---|
| Pulse (5-second) Hot Cranking Amps (PHCA) | 2150 |
| Cold Cranking Amps (CCA) | 1150 |
| 20Hr Nominal Capacity (Ah) | 100 |
| Reserve Capacity Minutes | 205 |
| Weight (lbs) | 77.8 |
| Weight (kg) | 35.3 |
As you can see from the above, the one Enersys/Odyssey/Diehard Platinum (These batteries are all the same and made by Enersys, The Diehard Platinum is no longer being made) Group 31 battery is similar to having 2 yellow top Optima’s. That’s good enough for me.
Hey, it’s 110 out, let’s rotate the tires and check to make sure everything is tight under the truck!
