Dual Batteries

I know this is under "Essential Mods", but this is only essential if you take your machine way out into the wilderness and/or use electrical accessories that can potentially consume more power than the engine can provide.

Note: the stock engine stator out put is 750 watts @ 5000rpm. The engine and transmission consume around 300 watts of that power, leaving only 450 watts-ish available for accessories (and much less at idle). Using the power steering can temporarily increase the load by as much as 350 additional watts, leaving a very little available power. A second battery provides a larger "buffer" for excess load, emergency start battery if the main dies, and via an isolator you can run accessories without the vehicle running for a while without risking not being able to start the vehicle.

Dual battery kits:

  1. Cobble your own together using a True brand isolator, a battery tray, and a battery.

  2. Trail Star Audio makes a great kit for a reasonable price, everything is included.

  3. AJK Offroad makes a great kit as well.

Dual Battery gauges / troubleshooting charging

This has come up several times "I'm looking at my dual battery gauge and it doesn't look like it's charging". And no, the battery was not charging. Here's the deal with the isolators: They will not connect the main battery to the secondary until the main battery voltage reaches 13.4 (the cut-in voltage). It will also disconnect if the total system voltage drops below 12.9 (the cut-out voltage) to prevent damage to the charging system.

The True battery isolator is a NOT a battery charger. It is an isolation device to protect your vehicles electrical system. If the secondary battery becomes depleted where connection to the main battery brings the system voltage below 12.9, you MUST connect the secondary battery to an external battery charger. It WILL NOT be recharged simply by riding the vehicle or lowering your accessory load. If using a battery tender, you must use a separate tender on your secondary battery!

Here's how to check: test the main and secondary battery voltage. Add the values together then divide the total by 2. If it's 12.9 or less, then your secondary is too depleted to be used or charged by the vehicle. For example: Main is 14.1, Secondary is 11.7. 13.9 + 11.7 = 25.6. And 25.6 / 2 = 12.8, thus the secondary battery cannot be charged by the vehicle.


Help! My blue light never turns off!

It's does...its just takes a while. Here is information from an engineer at TRUE: "The blue light will stay on until main battery voltage drops below the isolator voltage threshold. It will then keep the batteries separated so that your starting battery remains charged without the accessories attached to the secondary battery draining your starting battery."