Mechanic installed yesterday, not sure if working properly, going to have my mechanic check it out next week. He wanted me to run it over the weekend, so but right now, I see the blue charging light on, it never seems to go off, and I have solar panels as well, so I cant imagine it staying on all the time charging. We will see. UPDATE: Sending back for a replacement...the charge indicator light (blue) does not go out and unit get very hot. the light will go out when the starting battery and the aux battery run down. PLUS I have a solar panels and solar controller , so if the sun is out putting a charge into the aux battery the blue light stays on unitl after dark and the batteries run down. Will try a replacement as my mechanic said it should not operate like that to run both batteries down then shut off .

I was going to just install an 80a relay on a switch, but this thing wasn't much more. It's a great value. The mounting bracket could be sturdier, but that's my only criticism. Instalation was easy.

If you're running a second battery, I'd highly recommend getting this. You want to hear it, here it goes.

This is a smart battery isolator, charger, and jump starter all rolled into 1 palm-sized device. When installed correctly, you can run power into your secondary battery without affecting the main starting battery. The device stays on for less than a minute between shutting off your vehicle and running parallel with your main battery. So there will be a small parasitic draw for balancing both batteries during that minute.

This compact device has 3 connection points, main battery, secondary battery, and pre-wired ground. I highly recommend using a fused 4 gauge or higher cable from the main battery with the fuse or breaker fuse closer to the main battery, and a fused same gauge or lower wire out to your accessories from your secondary battery.

Following the instructions I realized it wasn't charging my secondary battery and wondered why. I later found that my main battery was faulting and after charging it for 8 hours didn't hold a charge past 64%. With that said, it will only charge your secondary battery IF your main battery is charged past 13.4V.

Once I got my main battery sorted (new one), everything was working as it should be. FYI, if either your main or secondary battery loses connection, the isolator will shut off by default. I tried to run the isolator in override mode to swap out the main battery without losing power, but found out that it simply shuts itself off. It's a good thing.

I also found out that this thing has a built in voltage spike regulator, similar to a power conditioner. But I wouldn't consider it to be a conditioner either. Before this, I had an 80A Stinger battery isolator/relay between the main and secondary battery. I also had a 150A fuse breaker between the secondary to my rear fuse box for my accessories that kept tripping only during vehicle startup without any accessories ON. Battery to battery was fine over 80A relay, but the surge of power introduced by the alternator kept tripping my 150A breaker. After installing this, I had my 250W light bar ON running out of the secondary battery without tripping the breaker during startup. So in short, it can detect power spikes and send the correct signals.

I highly recommend this if you're into the whole secondary battery and trying to stay within budget. What's $53 compared to potentially burning your entire electrical system (undercharging or overcharging) or getting stuck in a remote place without jumper cables.

Hopefully this helps you think about what this thing is actually doing and what you're protecting. I have a truck with a V8 5.0L engine and a stock 150A alternator, and the 125A/150A works for me. V6 and smaller motors with smaller applications can easily use 75A/100A system.

So far so good, If you're looking for an easy straight forward way to get it done. This is it. I have mine mounted to a second battery box and it gets moved and banged around a bit. Its been solid and performed well. When hooked up correctly you get a red power light. When alternator/car is running and sending power through it, light turns blue. Simple and easy...

This was easy to install once i found a spot, and does the job. It's nice not having to switch this manually, and much better looking than the solenoid based units. Haven't used the jumpstart function yet, and we'll see about longevity, but so far it's been brilliant.