Can I Run A 12V Outboard Off My Solar Array

[Gone2long]

... Actually that's a trick question, because I know that I can do it. But I would have to pull one of my four batteries, and I am concerned about the effect on the system if I do that.

So here are the details. I currently have two battery banks with two batteries in each, set up in parallel fashion. One bank is for the house, and one bank is for the engine. The solar array puts out 420W per hour. The electric outboard motor would be used as a backup to the 2stroke outboard I now use to power my dinghy.

What I would do is pull one of the engine batteries when I need it to power the 12V outboard. This should not cause a problem because I usually have way more power than I use, and, I could always switch my selector to the "all batteries" position and use the house batteries to start the engine.

I am concerned, however, about what effect running down the battery used for the outboard might have when put back into the system, significantly discharged. Would there be any negative repercussions other than diminishing the total power available for use on the boat?

It will obviously be a bit of a hassle popping in and out a heavy battery, but I am willing to put up with that inconvenience.

Thanks to all for your input,

G2L

[SV DestinyAscen]

Mate just get a proper battery for your electric outboard and leave the house bank alone. Also who wants to deal with connecting disconnecting circuits and resetting onboard systems to use a outboard.

Your suggestion is to you'll return a drained battery to a parallel circuit may result in damaging both batteries. Batteries are not ideal voltage sources and the internal resistance fluctuations between one drained and one charged battery is just a bad habit of getting into.

Your house system is fine - leave it alone and don't try to "make value" by draining it so you feel like you're maximizing it.

[StuM]

Once again - your solar panels does not put out "420 Watts per hour". Pleeeeaaaase read: http://www.cruisersforum.com/forums/...ml#post1933764 It will help you to understand the answers to your various queries.

SV_DA has it right, you don't want to pull a battery out of one bank, discharge it and them put it back in.

An obvious question: why do you dedicate half of your Ah availability to engine starting? That means that your house bank is only half of your available capacity and you are discharging it deeper than you would with 3 x house and 1 x starter battery.

If you want to use an electric outboard and have the spare solar available to charge it, put in another ACR (I assume that your current two banks use an ACR) and get another battery. (But do your sums first about the power requirements of the outboard, the size of battery you need and how much spare solar you have).

[SV THIRD DAY]

The short answer is not a chance..
Not even with 1000W of solar.

It's the undoable dream that falls apart once you start to do the solar Amp Hour math compared to the Amp Hour math of an electric outboard.

[Badsanta]

I like the guy who couldn't understand why putting an alternator on his electric motor wouldn't work.

[StuM]

Originally Posted by Badsanta

I like the guy who couldn't understand why putting an alternator on his electric motor wouldn't work.

Great idea - charge the battery while motoring!

[Gone2long]

Originally Posted by SV DestinyAscen

Mate just get a proper battery for your electric outboard and leave the house bank alone. Also who wants to deal with connecting disconnecting circuits and resetting onboard systems to use a outboard.

Your suggestion is to you'll return a drained battery to a parallel circuit may result in damaging both batteries. Batteries are not ideal voltage sources and the internal resistance fluctuations between one drained and one charged battery is just a bad habit of getting into.

Your house system is fine - leave it alone and don't try to "make value" by draining it so you feel like you're maximizing it.

I get the point(s), and they make sense; but, just for argumentation's sake, one way to get around damaging either battery would be to disconnect the charged battery when I replace the discharged battery back into the bank. Would work, no?

[Gone2long]

Originally Posted by Badsanta

I like the guy who couldn't understand why putting an alternator on his electric motor wouldn't work.

Now we know why they call you "Bad" ; )

G2L

[Gone2long]

Originally Posted by StuM

Once again - your solar panels does not put out "420 Watts per hour". Pleeeeaaaase read: http://www.cruisersforum.com/forums/...ml#post1933764 It will help you to understand the answers to your various queries.

SV_DA has it right, you don't want to pull a battery out of one bank, discharge it and them put it back in.

An obvious question: why do you dedicate half of your Ah availability to engine starting? That means that your house bank is only half of your available capacity and you are discharging it deeper than you would with 3 x house and 1 x starter battery.

If you want to use an electric outboard and have the spare solar available to charge it, put in another ACR (I assume that your current two banks use an ACR) and get another battery. (But do your sums first about the power requirements of the outboard, the size of battery you need and how much spare solar you have).

The short answer is "because that's the way the boat was configured when I bought her", which was less than two years ago; and, never having owned my own yacht before, I am still learning how everything works, or when it doesn't, why and how to fix it..

Actually, one of the engine batteries gave out a while ago, and I have been running the boat ever since with only three batteries, which realistically is all I need. I've never come close to draining any of the batteries, and when I asked what the problem was with the engine battery that conked out, the technician told me "it was over charged."

Have no idea if he knew what he was talking about or how he could possible tell, and the controller seems to be working fine; however, that is what started me wondering what I could do with the "excess" of power that I apparently have.

Thanks for sharing your expertise and experience.

G2L

[newhaul]

Just buy a purpose built battery for the electric motor and have a marine electrician install a charging station for the battery. Considering its for your tender you won't be using it constantly but intermittently
Using one of your start batteries is not a good idea at all. The increased usage and deep cycling of one will have a rather large negative effect on the entire system u would find yourself replacing both batteries much sooner. So just spring for a new deep cycle battery for the trolling motor.

[SV DestinyAscen]

Originally Posted by Gone2long

I get the point(s), and they make sense; but, just for argumentation's sake, one way to get around damaging either battery would be to disconnect the charged battery when I replace the discharged battery back into the bank. Would work, no?

How would you know when you can reconnect either? You think your batteries will last with this nonsense? You like resetting your house systems to use an outboard?

Ultimately do whatever you want since it is your boat. But it's a bad habit to mess with good systems for no reason or improvement and ignore advice.

[Gone2long]

Originally Posted by newhaul

Just buy a purpose built battery for the electric motor and have a marine electrician install a charging station for the battery. Considering its for your tender you won't be using it constantly but intermittently
Using one of your start batteries is not a good idea at all. The increased usage and deep cycling of one will have a rather large negative effect on the entire system u would find yourself replacing both batteries much sooner. So just spring for a new deep cycle battery for the trolling motor.

Good advice, for folks who live in a civilized country, but, unfortunately, I don't. I have been to a number of marinas in this country including the biggest and supposedly the best, and, believe me, no such thing as a real "marine electrician" exists. I'm sure that large, commercial shipping companies employ such folks, but the yacht clubs and marinas lack facilities and qualified personnel.

That said, I do appreciate the spirit and logic of your advice, and my work around would be to devote a separate battery (as everyone advises) to the outboard and to use my portable generator to charge it. Now, I know that such is probably not the best way to do things, but it seems to be my only relatively sensible option.

Thanks for your help.

G2L

[Cotemar]

G2L,

This is what we use on our electric dinghy if it may help you or give you some new idea's.

Minn Kota Riptide 45 / T 36”
45 lbs thrust
36” shaft
Purchased 6-19-2016 for $299

GreenWorks GBA80400 80V 4.0Ah Lithium Ion Battery $278 on Amazon
It has 40 -18650 batteries inside. Weight is 5.5 pounds

Greenworks GCH8040 80V Lithium-Ion Single Port Battery FAST Charger $70
Will fully charge battery in 30 to 45 minutes

80V to 12V DC to DC Voltage Step Down Converter $70 on e-bay

We charge this battery using our current 500 watts of solar panels.

[akprb]

Just out of curiousity do you use this motor as your "daily driver" or for some occasional fishing?

I read this and first thought was why:

"It will obviously be a bit of a hassle popping in and out a heavy battery, but I am willing to put up with that inconvenience."

If it's the environment a little 2hp Honda probably less footprint over its lifespan. If for fishing that makes sense.

Pay little attention to me, I'm in the 25hp 2 stroke camp ��

[Colin A]

Originally Posted by Cotemar

G2L,

This is what we use on our electric dinghy if it may help you or give you some new idea's.

Minn Kota Riptide 45 / T 36”
45 lbs thrust
36” shaft
Purchased 6-19-2016 for $299

GreenWorks GBA80400 80V 4.0Ah Lithium Ion Battery $278 on Amazon
It has 40 -18650 batteries inside. Weight is 5.5 pounds

Greenworks GCH8040 80V Lithium-Ion Single Port Battery FAST Charger $70
Will fully charge battery in 30 to 45 minutes

80V to 12V DC to DC Voltage Step Down Converter $70 on e-bay

We charge this battery using our current 500 watts of solar panels.

Quick question, what's the reasoning behind the 80V battery instead of buying a 12V one? I assume the energy density is good but I would assume the losses in dropping to 12V would negate some of that?