Charging 24VDC battery with 12VDC output from outboard-gctid359147

[Guest]

I've got a little tin fishing boat with a bow-mounted electric trolling motor. I want to charge the trolling motor's 2 deep cycle batteries by running my main outboard. The alternator has enough capacity to do this, but the outboard's alternator output is 12VDC.

What's there:

• A pair of deep cycles wired in series supply 24VDC to the electric trolling motor.
• Primary starting battery is a regular cranking battery; 12VDC.
• When plugged into shorepower, a 3-bank smart charger charges all 3 batteries.

Has anybody tried the Yandina Trollbridge24? Is this the right way?

Here's a simple schematic. I have simplified it by eliminating the local ground and positive buss bars, fuses, breakers and battery disconnect switches.

http://baylinerownersclub.org/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=41998&g2_serialNumber=1

[JimMc]

The Yadina Trollbridge 24 seems the ideal solution as it is devised for this exact application. As it is on sale for $97 I would try it.

[img]/media/kunena/attachments/vb/662121=25175-Trollbridge24.gif[/img]Given a bit of thought this could also be accomplished with a switch and relay. If you are looking for a home built solution I would be happy to sketch it out.

[Guest]

JimMc wrote:
The Yadina Trollbridge 24 seems the ideal solution ...

If you are looking for a home built solution I would be happy to sketch it out.

The Yandina does seem right Jim. But I've had no experience with it. I do recall that Lolar has used Yandina stuff in the past and been happy with it. If he doesn't appear shortly I'll give him a call.

Yes, I would love to see what you can come up with using a relay/switch combination.

[JimMc]

I used a Yadina combiner for charging my house bank when we had a 285. It worked well.

I will sit down tonight and see what I can come up with. It sounds simple enough.

[Guest]

I had a Yandina combiner on my 2455. I broke the case screwing it down too hard. I e-mailed them asking if I could buy a new case. They said they would send me an ENTIRE NEW UNIT since they have a no-questions full lifetime guarantee. I insisted on just the case and they sent one free in a couple days.

THAT is customer service.

[Guest]

[img]/media/kunena/attachments/vb/662150=25177-Troll24.jpg[/img]This really is the simple way to do it. All automatic, no switches or relays to worry about.

[jmcannonball]

$97.95 on sale right now.

http://www.yandina.com/index.htm

[JimMc]

I sketched it out and it can be done with a DPDT relay and a SPST switch to control the relay and in turn power the trolling motor or charge.

I can't get it down to as few wires as shown but likely some of the connections occur internally in the Yadina device.

[Guest]

JimMc wrote:
I sketched it out and it can be done with a DPDT relay and a SPST switch to control the relay and in turn power the trolling motor or charge.

I can't get it down to as few wires as shown but likely some of the connections occur internally in the Yadina device.

I see you're working late - 0200h!

That's great Jim. Thanks. I have a couple of DPDT relays. Will need to confirm that one of them will handle 50A or so.

I wonder what Yandina does to automatically switch the unit when it senses a load?

[JimMc]

In the little graphic of theirs I posted it does show a switch. Whether that is actual or virtual and for illustration I do not know.

If you try what I drew use some small batteries and a meter in place of the trolling motor to test it first. Just to be safe.

Umm 2:00 AM , well it actually took me a few hours to figure out and to get it drawn clean enough to post. It became a personal challenge to figure it out. Besides I did say I would do it for you.

[JimMc]

From the Yadina instructions.

The Trollbridge24

® automatically puts the batteries inseries whenever you turn on the trolling motor. When nottrolling, there is 12 volts going to the motor to detect whenit gets turned on. Within a fewmilliseconds of being turnedon, the voltage switches to 24 volts and the GREEN LED

turns on.When the trolling motor is off for about 20 seconds thebatteries are put back in parallel. If the main engine isrunning both batteries will receive a charge when they arein parallel and both are available for starting or house

loads.



BTW - I did not design mine to function as they describe. With my design you are either charging both or trolling and charging the starting battery (if the engine is running).

Their design includes electronics to sense the demand when the trolling motor is turned on.

[706jim]

Before you go to all of the trouble of buying some fancy battery charger for your 24 volt system, try removing any load from the outboard (disconnect your 12 volt battery), start it up and measure the output voltage from its alternator. I bet you'll find it to be a LOT higher than 12 volts; probably enough to supply a charge to two 12 volt batteries in series. I seriously doubt that you would overcharge two batteries from the (unregulated) output from a small outboard motor while running it any reasonable amount of time.

Just a suggestion.

[Guest]

706jim wrote:
Before you go to all of the trouble of buying some fancy battery charger for your 24 volt system, try removing any load from the outboard (disconnect your 12 volt battery), start it up and measure the output voltage from its alternator. I bet you'll find it to be a LOT higher than 12 volts; probably enough to supply a charge to two 12 volt batteries in series. I seriously doubt that you would overcharge two batteries from the (unregulated) output from a small outboard motor while running it any reasonable amount of time.

Just a suggestion.

Thanks 706jim. The outboard is a 4-cylinder 4-stroke Suzuki DF140, so it has a real 40A alternator with voltage regulator. Water here is still ice; I did a quick voltage check with a cheap analogue meter that I had out in the barn. Alternator output is about 14.5V. I will get my digital Fluke on it once I'm in the water, but I know I can't charge at 29V.

[Guest]

JimMc wrote:
From the Yadina instructions.

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The Trollbridge24

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automatically puts the batteries inseries whenever you turn on the trolling motor. When nottrolling, there is 12 volts going to the motor to detect whenit gets turned on. Within a fewmilliseconds of being turnedon, the voltage switches to 24 volts and the [/SIZE][/FONT][/SIZE][/FONT][FONT]Arial wrote:
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turns on.When the trolling motor is off for about 20 seconds thebatteries are put back in parallel. If the main engine isrunning both batteries will receive a charge when they arein parallel and both are available for starting or house

loads.

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BTW - I did not design mine to function as they describe. With my design you are either charging both or trolling and charging the starting battery (if the engine is running).

Their design includes electronics to sense the demand when the trolling motor is turned on.

I think the switch they show in their little gif image is the switch on the trolling motor. Thanks again for taking time Jim.

[JimMc]

Revised to have the trolling motor switch control the relay system. Switch S1 is the trolling motor foot switch.

The value of R1 would be based on the current demand of the coil in the relay you choose.