Battery Isolator trouble

[waterfront]

I recently had a terrible scare aboard. I have an electric bow thruster which has a dedicated battery. When I first bought Waterfront, a 35 ft Present Sundeck Trawler, the P.O. had not included the thruster battery into the charging system. To correct this problem I purchased a MANTA II solid state battery isolater and installed it to include all battery banks, three seperate banks. The battery for the thruster went bad and in the process of changing it out I reversed the polarity for a SHORT time, maybe 10 seconds. The battery isolater caught on FIRE!! lucky for me I had an extinguisher handy so most of the damage was from smoke. I purchased a new Sure Power isolater which is now installed. BE AWARE of the dangerous potential of fire with this isolator.

 

[Capn Chuck]

Get rid of the isolator and don't install another one. An isolator will typically have a 1.5 volt drop across it and as a result, the attached battery never gets fully charged. Use a battery combiner instead or add a separate charger for the thruster battery. Chuck

 

[FlyWright]

I agree with Cap'n Chuck. Look at the Blue Sea ACR as an alternative. No voltage drop across a diode. I installed the Yandina combiner, but the Blue Sea is much more stout.
SI-Series Automatic Charging Relay — Blue Sea Systems

 

[FF]

$ 18 minibucks at the RV store and you have a solenoid that does not catch on fire.

OR loose voltage during charge has a positive disconnect and is a snap to live with.

FF

 

[Vyndance]

2 votes for the ACR

 

[jeffnick]

I have the Yandina and like it. It's nice to have the manual over-ride open/closed.

 

[FlyWright]

I have the Yandina and like it. It's nice to have the manual over-ride open/closed.

I have the switch, but have not installed it yet. I'm still debating it since I don't want to mess it up and accidentally leave it in the closed (tied) position. Might be nice to have it connected to open the combiner at times when I'm trying to charge just one bank. I might just hook up the override open part of the switch. If I need the banks tied together, I have a set of Perko Switches for that purpose.

 

[HopCar]

I just bought a Blue Sea Add-A-Battery kit. It has the Automatic Charging Relay (ACR) plus a switch that allows you to combine the house bank with the starting battery if you need to.

 

[rwidman]

I recently had a terrible scare aboard. I have an electric bow thruster which has a dedicated battery. When I first bought Waterfront, a 35 ft Present Sundeck Trawler, the P.O. had not included the thruster battery into the charging system. To correct this problem I purchased a MANTA II solid state battery isolater and installed it to include all battery banks, three seperate banks. The battery for the thruster went bad and in the process of changing it out I reversed the polarity for a SHORT time, maybe 10 seconds. The battery isolater caught on FIRE!! lucky for me I had an extinguisher handy so most of the damage was from smoke. I purchased a new Sure Power isolater which is now installed. BE AWARE of the dangerous potential of fire with this isolator.

I fully agree with most of the others that a battery combiner is far better than a battery isolator, but your ststement, "BE AWARE of the dangerous potential of fire with this isolator." is unfair to the manufacturer. He didn't connect the battery backwards, you did.

You are very lucky you didn't damage anything else.

 

[waterfront]

Rwidman you are correct that I fouled up. I also found that this isolater is no longer available, so it is a mute point anyway.And also I am very lucky nothing else was damaged.

 

[rwidman]

Rwidman you are correct that I fouled up. I also found that this isolater is no longer available, so it is a mute point anyway.And also I am very lucky nothing else was damaged.

As others have alluded to, a battery isolator uses diodes to seperate the batteries. This results in a voltage drop across the diodes and incomplete charging of the batteries.

A battery combiner (voltage sensing relay or "VSR") measures the voltage and when the engine alternator is providing charging, connects them together for charging. When the engine is shut off, there is no charging current and the relay seperates the batteries.

It's really not much more than an automatic 1 / 2/ both battery switch that's often seen on smaller boats.