Cole Hersee 48120 Battery Isolator

This item is well-constructed and was easy to install in place of a failed unit from a different manufacturer. It worked as expected from the get-go; the application was a class "A" RV with two battery banks and the result is that both banks charge as originally designed using a "smart" charger/converter in addition to the engine alternator. A nice item at a good price, super-fast shipping as well.

Installed easily on dual battery system for my boat. Works perfect and went with 140 amp isolator to add some buffer for my 120 amp charging system. Was recommended from reviews.

Good value

I have the unit intended for Delco alternators that sense the battery voltage to cue the internal voltage regulator. It has three high current lugs and a smaller lug to tell the unit that the host vehicle is "keyed on"It is not trivial to get the two control wires from the vehicle to the Isolator. The "S" terminal at the alternator must be identified, and a connection made to it. An aftermarket 4-pin connector will help, but you will have to break the F and L leads and connect them back to the vehicle wiring harness; and you'll have to extend the S-wire to one of the isolated batteries.In addition, you'll have to find a place to tap the vehicle wiring harness to bring an "IGN(ition)" voltage to the Isolator when the vehicle key is on. In my 2008 Chevy Express van, I could find no such connection either fuse box. The easy way out of that is to use a piggyback fuse from your car parts store -and then identify a circuit that comes "hot" only when the key is on.You'll also have to run a cable from the alternator's BATT(ery) terminal (the big one on the back of the alternator) to the central lug on the isolator.I really dislike the mounting tabs. The u-shaped notches are awkward, and too close to the sides of the unit to allow a nut and a wrench or a washer, nut and wrench.Once installed, the unit seems to work just fine. You can measure the 0.7-volt "diode drop" between the alternator lug and the battery lugs --reinforcing the need for the S-wire from the alternator. (to get past the 0.7-volt loss between the alternator charging voltage and the voltage the battery sees)

This is an exact replacement for the one with failed diodes that I took out after MANY years of service.It was bought from Amazon Marketplace, and labeled as 'used' - but it wasn't.Open box, original box destroyed, or whatever, it was clearly a new product, as there was not a mark - and not even dust - on it. As I had one already, I know that the attractive blue anodizing will scrape off at the screw hold-down locations; there wasn't any indication that it had been mounted.Likewise the posts and bases would show marks from the lugs when attached.So, unless it clearly shows having been used, I think you can rely on Amazon Marketplace "used" products to be a much less expensive alternative to the same item in its original packaging.As to the isolator itself, it's an industry standard. We use it to split off our windlass and starter batteries from our house bank aboard Flying Pig, our home, a Morgan sailboat.It arrived after a curiously very long wait, having been in transit for more than two weeks; the time line on the tracker showed out for delivery for more than a week. Several other items ordered arrived as expected, so there must have been some glitch along the way. Fortunately for us, we had many other things to do, and its later arrival was not an issue.Still, as a "used" item, it far surpassed any expectations.

working great

Good product

This item simply doesn't work. It looks great, but it's really just a very expensive distribution block. It doesn't isolate the batteries at all.I put the resistance meter on it when I first got it and it showed minimal resistance in all directions between all posts. I am not an electrical engineer, so I thought maybe I just didn't understand how it worked and that it would actually accomplish the task when it had a load on it.So I installed it and hooked it up according to the included instructions. Finally got around to testing it today (by leaving the lights on for a couple hours) and the lights drained both batteries. Even though one of the two batteries is only connected to the starter and this device.When all batteries are disconnected, there is no connectivity between the starter cable on the rest of the electrical system. Therefore I know the drain came through the isolator.I'm going to leave it, because it looks nice and I don't feel like redoing all my work. Someday I'll get around to buying and isolator that actually does what it's supposed to do and replace this device.I gave it to stars, because it's fairly inexpensive and it really does look nice under the hood. If I had just wanted a battery distribution block, this item would be perfect.