Sorting out battery charger and shore power questions

[jssailem]

Perhaps removing the "motor" or, if you feel you need to identify it in the diagram, label it as an OUTBOARD. It is really no different than a light bulb to your system. The rest of the graphic speaks to "Charging Sources".

As you are planning to use an AC source to help charge your batteries (the "Charger") then you need to understand galvanic isolation and the proper way to "Ground" a charger on a boat. Reading MaineSail you will see that the "Typical Battery Charger" used in the automotive world will kill boat batteries and provides an opportunity "an electrical hazard on a boat". They just are not UL approved for boats.

The charger is connected directly to both batteries independently.
This tells me that the out put of the charger is providing DC power to the batteries.

The charger is not connected to the panel or shore power system. It must be plugged in separately. (for now I'm thinking that I will plug this into an outlet so I can use the shore power plug for charging when needed)
Does this mean you run an extension cord from a 110 source on shore to the boat and then plug the charger in to the end of the cord? Deciding to use the "Shore Power Plug" raises questions. It appears in your diagram the Shore Power plug is connected to the 1/2/B plug. This would mix AC and DC power in the boat. That is a big NO NO NO NO.... I am guessing it is not but if my guess is wrong it should be corrected before fire or electrocution occurs.

* I do need to use the 1/2/All switch to use the house lights and various accessories.
This switch is a way of turning on or off the DC systems in your boat. Since you use an outboard and there is no alternator involved providing power to the batteries through the switch it's use for DC only power is fine.

* Shore power works for the 110 outlets when plugged in.
Lets identify "Shore Power" as AC power. That way you recognize the difference and you keep the systems TOTALLY SEPARATE. Like water and electricity do not mix or play well. AC and DC power are cousins that work best when they are on different planets.

 

[chriscampbell]

Love this forum. Thanks for all of your replies so far!

I made a couple changes to the diagram to help answer questions. Sorry for the confusion. I'll try to address a couple of questions.

@Richard19068 I agree that's strange the manual says to remove the batteries from the boat. It's supposed to be a marine-capable charger.

@jssailem I assume (but have not confirmed yet) that the outboard is providing some charge via the alternator.
Yes, I must plug the charger directly into an extension cord. It is not connected to the AC shore power system.
Regarding the AC vs DC - sorry for the confusion. I updated the diagram. We have an AC/DC panel, with AC distribution and a DC switch.

 

[rgranger]

You’re not going to get very much electricity from your outboard. I’m guessing at most you have a six amp charger and that’ll only be 6 A at full throttle. You won’t be running the boat at full throttle most of the time. I guess every little bit counts.

 

[jssailem]

It's supposed to be a marine-capable charger.

Marketing vs Legality... They think they solve their problem by specifying where the batteries must be to be charged.

Actual Marine boat chargers are designed and built differently than the unit you have.

One analogy would be to look at your speedometer in your car. Can you or should you drive your car at the max speed on your speedometer? Should you do it regularly, 10% 35% 65% of the time?

If not... why do they put a speedometer in the car that says 300 km/h = 186 mph

Think about it. For your own safety and a longer life for your batteries, consider acquiring a battery charger that will be good for you and your boat.
This are a few of the certifications your charger should state.

It is not for me.. But for you. It is your boat and in this country you can do what pleases you on your boat.

 

[dlochner]

First, you have a very non-standard schematic of your electrical system. That makes very difficult to understand and for others to advise you.

It looks like you have a ground loop, which should be avoided as it provides multiple paths to ground.

There is no need for a dedicated start battery on an outboard. If the battery is dead, use the pull cord. The current from an OB motor is not regulated, i.e., the faster the motor is running the higher the output and the output is pretty low, at most about 6a. The primary purpose of the electrical output is replace the charge in the battery from starting and to run low current devices like running lights or small electronics like a fish finder.

AGM batteries are not a good choice for you unless you plan to recharge the battery every night or two. AGMs do not tolerate being in a partial state of charge for extended times. They also require fairly specific charging protocols and are subject to dying a premature death.

The 10 watt solar panel is basically worthless. It puts out less 1 amp, which will keep a fully charged battery charged, but won't recharge a battery.

There is a lot of misinformation on boat electrical systems out there. A few reliables sources are:

Marine How To - DIY for Boaters - Marine How To

For DIY boaters in an attempt to try and keep the sport as affordable & safe as possible. How To articles for sailboats and powerboats.

www.marinehowto.com

https://www.Boathowto.com

The Pacific Yachting Systems YouTube Channel

The Boat Electrical Systems group on FaceBook

 

[chriscampbell]

First, you have a very non-standard schematic of your electrical system. That makes very difficult to understand and for others to advise you.

It looks like you have a ground loop, which should be avoided as it provides multiple paths to ground.

There is no need for a dedicated start battery on an outboard. If the battery is dead, use the pull cord. The current from an OB motor is not regulated, i.e., the faster the motor is running the higher the output and the output is pretty low, at most about 6a. The primary purpose of the electrical output is replace the charge in the battery from starting and to run low current devices like running lights or small electronics like a fish finder.

AGM batteries are not a good choice for you unless you plan to recharge the battery every night or two. AGMs do not tolerate being in a partial state of charge for extended times. They also require fairly specific charging protocols and are subject to dying a premature death.

The 10 watt solar panel is basically worthless. It puts out less 1 amp, which will keep a fully charged battery charged, but won't recharge a battery.

There is a lot of misinformation on boat electrical systems out there. A few reliables sources are:

Marine How To - DIY for Boaters - Marine How To

For DIY boaters in an attempt to try and keep the sport as affordable & safe as possible. How To articles for sailboats and powerboats.

www.marinehowto.com

https://www.Boathowto.com

The Pacific Yachting Systems YouTube Channel

The Boat Electrical Systems group on FaceBook

Thanks, Dave. I wouldn't claim to know how to create an official schematic. This drawing was just so I could record, and start to wrap my head around, how our boat came set up.

In my reading so far, it looks to me like dual-battery installations with a DC battery switch tend to be represented as having their negative terminals connected to each other, with positive terminals running to the DC switch. I'm sure there is something there I'm missing, but this appears to be the way we are wired currently.

I had a 10watt solar charger on our previous boat (a Hunter trailer sailer) and I never had to plug it in again after I installed that. I was hoping it would work again on this boat. I guess I'll see if it helps keep the batteries alive.

Based on your comment about the starter battery, it sounds like you might be in favor of setting them up in parallel and just increase the amp hours rather than switching?

Thanks for your response. I'll check out the links you provided.

Chris

 

[dlochner]

Thanks, Dave. I wouldn't claim to know how to create an official schematic. This drawing was just so I could record, and start to wrap my head around, how our boat came set up.

In my reading so far, it looks to me like dual-battery installations with a DC battery switch tend to be represented as having their negative terminals connected to each other, with positive terminals running to the DC switch. I'm sure there is something there I'm missing, but this appears to be the way we are wired currently.

I had a 10watt solar charger on our previous boat (a Hunter trailer sailer) and I never had to plug it in again after I installed that. I was hoping it would work again on this boat. I guess I'll see if it helps keep the batteries alive.

Based on your comment about the starter battery, it sounds like you might be in favor of setting them up in parallel and just increase the amp hours rather than switching?

Thanks for your response. I'll check out the links you provided.

Chris

The schematic does not have to have all the correct symbols and pictures like the professional schematics. It simply needs to have straight lines, clearly labeled parts, with no distractions.

When I was reconfiguring my DC system, I started with this schematic. It was created in MS Word with the Draw functions.

 

[Scott T-Bird]

Based on the fact that he has an outboard motor and a starter battery that is only used to start the motor, I think I would I think simply disconnect the starter battery from the 1/2/B switch. The outboard alternator should be enough to keep the starter battery alive and the alternator is doing nothing for the AGM battery anyway. Also, I don't like the charger connected to batteries with 2 different chemistries, assuming the starter battery isn't AGM. There is nothing wrong with using the AGM battery exclusively for the house DC power loads exclusively. It isn't needed to start the outboard if you have a starter battery. Besides that, with a 1/2/B switch you may not be starting the outboard with the starter battery anyway, unless you are switching to that battery. We don't know how you use that switch, so we don't know anything about how you are managing the battery loads to begin with.

To summarize:
1. I would disconnect the starter battery from the 1/2/B switch and just run the outboard independently off the single battery, assuming it is in decent condition and holds a charge just off the engine usage.
2. If the AGM battery is a good battery, I would get a battery charger that will charge for AGM chemistry and set it up properly wired to the AC breaker. Connect a galvanic isolator for good measure, but that may not be very important, depending on your location.
3. You don't need a 1/2/B switch but you can use it simply as an on/off switch.

A more elegant solution would be to set it up with a DCP switch as shown in Dave's diagram, which truly separates the starter battery and house battery usage, but you need to read about the variations and how it differs from a 1/2/B switch. My personal preference is using a DCP switch. If you want to charge the both the starter and house battery with an AC charger, you should use the automatic charger relay (ACR) in conjunction with the DCP switch. Blue Sea sells these items together for just the situation that you have.

I don't know the charger that you have, nor do I care to learn anything about it. I suspect that it is a very simple charger that isn't really applicable to your marine usage. Charging systems for sailboats can be relatively complex and you will be doing yourself a favor to do the research and learn more about it. You have a simple application, with a small boat and an outboard. But you want to be able to depend on your house battery to supply all your needs while you are away from the dock. The health of your house battery is the primary consideration in my mind. With a proper system you can rely on your batteries.

You actually have a good start by incorporating a solar charging system. With the correct format and utilizing an ACR, you can use the solar power to make sure the starter battery is topped off.