Blue Sea 7620 ML-Series Automatic Charging Relay (Magnetic Latch) 12VDC, default title

High quality latching relay, weather proof, marine quality. Reason I only gave it a 4 star install rating is because putting in the remote switch takes some work and minor wiring knowledge, otherwise if you don’t need the remote this is a simple attach to a solid surface, add two heavy gauge battery wires and ground it and it instantly goes to work. When I first installed this relay on my RV coach, one battery bank was lagging in staying charged. Within a few hours, while installing the remote switch and fishing the wires thru, both battery banks were equalized at 13.5 vts. Magnetic latching, uses very little power doing this. It does make a loud “thunk”when switching. I installed a thick piece of rubber backing on the wall behind it to lessen the noise.

The product gets 5 stars plus. It is fantastic and solves the problem of diode based isolators in so many motorhomes and boats. If you want a full charge on your motorhome and boat batteries, throw the diode isolator away and use this solenoid switch with dash mounted switch (provided). You get automatic connection or isolation of batteries, manual isolation or manual connection. It has all the delays programmed in and will not connect defective batteries. It does more than you could expect by having 2 engineers onboard to manage your battery charging. It works with both self excited and remote sensing alternators where diode isolators require remote sensing to get close to a normal charge. No loss of voltage across the diodes (.7 volts of 12.6 volts. Batteries will last longer and you'll have a full charge from either the alternator or the on-board charge. Even connects when solar charge occurs.

This switch is heavy and robustly built. I used it for a custom dual battery installation on my 4x4. If it’s good enough for out on the water use it’s good enough for my build. I like the flexibility of having the switch available on my dash to see the batteries tie in automatically or the option to tie in manually. It is on the pricey side, but I’m fairly certain it’s going to last quite a long time.

Well designed and built. It does exactly what it should do. Easy to install with thorough instructions.

Great product

Joining large house battery to start battery/alternator in a small RV Work great....no brainer for RV or Boat install. Buy one

This product seems to have stopped working after 2 years. Not sure why but it really sucks

No more surprises starting my 2013 Tahoe.