12V 140Amp Dual Battery Isolator, Ampper Battery Voltage Sensitive Relay (VSR) Smart Battery Isolator with Voltmeter and Manual Control Button for Car and More (with Battery Terminals, NO Cable)

I have added an auxiliary 150 AH Gell battery to my van and this switch does a great job of keeping it charged and then cutting off when needed. Paid 145 Dhs for it. Worth the money. It is quite heavy and when it switched off and on you can tell there are some heavy parts in there. The manual over ride is quite a good feature too, although I'm not using it.

Great addition. I added this to our pontoon to keep the starter battery up for starting. This works as described. I did have to get marine grade wire $$. That is the big cost. I had to run the wire and protect it and secure it. Just take your time and do it right. No short cuts LOL.I like the readout to see the voltage.I added CTek charge ports for each battery on the console to also verify the state of my battery. The boat never started so good in cooler weather. And the starter battery does not run down while we play the stereo with the motor off.We live in the Midwest, and store boats in the winter.

I bought this because of the voltmeter feature. I used 2 AWG wire, this device uses M6 (1/4”) terminals. The device was probably meant to use #4 AWG. I had to flatten the crimp terminal flared edges to get these wires to allow the device to fit the backplate with no gap/interference. The pre-notched cover holes had to be opened up to allow the larger #2 AWG wires to pass with heat shrink tubing on them.

Installed in my truck and 2 Days later out of the blue it just died. I have to say I'm a pretty forgiving guy but this does not speak very highly for their quality control department. But it's an awesome idea when it works, I traded it in for a $20 stinger relay and have not had a problem since.

In my case did not appreciate the auto hi voltage shutdown.fyi it sensors both batteries for charging switching.