12V House Bank to Charge 24V Bow Thruster Battery

[geoffr]

I'm thinking of installing a 24V bow thruster (see Propellers & Drive Systems), but my house bank/alternator/Solar from which I will charge from is 12V. I have seen systems from Sterling and Vetus that will allow for this.

Anyone have any experience with these (or others) that they can report on?

Any other thoughts?

Geoff.

[Andina Marie]

If the bow thruster is rated at 80 amps or less maximum you can use a Trollbridge24 for under $100. It puts the batteries in parallel for charging and switches them to series when you need 24 volts for the bow thruster. But it is only rated for 80 amps which may be too low for many bow thrusters.

[capn_billl]

It can be done with diodes.

[sdowney717]

somewhere on here it has been done using headlight beams.

[DeepFrz]

Another option is to use a 24 volt charger driven by an inverter connected to the 12 volt house bank.

[Andina Marie]

It cannot be done with diodes.

The charging method using headlights article is at 24 Volts from 12 but it is not automatic so you would have to go forward to switch it on or add a remote control power relay.

A 24 volt charger is an option but a dual 12 volt charger run from the inverter would be a better choice for battery life.

There is another product I've never used that may be the simplest solution. It is a DC voltage doubler you can use to charge the 24 volt battery. You can find it on web site Backwoods Solar Electric Systems and search for O-SOL DOUBLER. Check with the vendor that it is suitable for charging a 24 volt battery and if it has sufficient output.

[capn_billl]

You can make a voltage doubler directly from an alternator output using only diodes, from a pure DC source you must also use a relay. or this...

Trollbridge24 COMBINER
Charge your 24 volt trolling battery from a 12 volt supply.
Click picture for details and orderingTrollbridge24 Combiner
$124.95 List Price
$97.95 Sale Price

[sdowney717]

24 Volts from 12

[boatpoker]

I did this on my last boat using a Belarus (russian tractor) series/parallel solenoid. Cost me about 100 dollars. I had to install a relay and a momentary switch. Hold down the momentary with my thumb while moving the joy stick with my finger.

I originally put in an on/off switch but it fried the series/parallel solenoid when I forgot to turn it off.

At the time I looked at the Vetus solenoid but they wanted $1,100.00

[dohenyboy]

I had one of the Vetus relays. It went bad after some years. Yes they are expensive.
This relay lets you charge the batteries with 12v but then when it's activated outputs 24v to the windlass or in my case bow thruster
I avoid using relays if I can. I did not replace the relay.
I added a second, 24v alternator to the engine to charge the batteries.
You could also make your own relay, just use solenoids rated for the load, if you are good at electrical theory.
Basically, the 2 12v batteries are in parallel while charging; when you activate the windlass/ thruster, you put them in series.

[Andina Marie]

Just a little warning about DIY using solenoids as suggested.

Having been making the Trollbridge24 for nearly 5 years now I warn against casual parallel/series switching wihout mechanical or electronic safety interlocks. If you look at the schematic it only takes one relay to fail to operate, or stick shut and you have a dead short across the battery(ies). If you go this route, please put a safety fuse in each positive battery lead rated above the stall current of the winch and less than the worst case value of the CCA of the battery.

The Trollbridge24 not only has the safety interlocks but it detects when a load current is drawn while the batteries are in parallel and switches automatically to 24 volts. This saves going to the winch to switch to 24 volts or having to add cables for a remote control, the normal (remote if you have it) on/off will switch it to 24 volts.

Keep in mind that it was designed for trolling motors, not winches or bow thrusters and it can only handle motors up to 2 horsepower.

[Catalysis]

You may want to consider a Sterling Power IP68 12v to 24 v charger which can be configured to charge any type of battery - AGM etc
Paul

[Florida Mike]

This web address as a series parallel relay ( 12 Volt DC 1500 amp Starter relay replaces Delco 1119845 - 9-845 10-D1602. ). It is designed for large diesel engines. It will do the job.

sdowney717 , diagram is a good design considering how rarely you’ll use your bow thruster. The only changes I would make is to add fuses or circuit breakers. Just my two cents, Mike.

[geoffr]

All,

thanks for the comments - after sitting back and looking at the complexity vs simplicity, weight (we are a cat so this really matters up front!), costs we have decided to install a 12V thruster.

Geoff

[Catalysis]

http://www.sterling-power-usa.com/li...ct%20Sheet.pdf
Geoff:
I just installed these 12v to 24v waterproof chargers form my thrusters.
Paul