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Old 11-02-2014, 06:28   #1
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Battery charger, shorepower, inverters, WHAT?

Hi,

Since I don't know that much about electrical systems, I thought I'd ask you guys.

I've been looking at an old Albin Vega which would be perfect, but I'd like to do some upgrades on the comfort-side of things, in particular adding some electronics.

There is currently a 70Ah battery on board.

My question is, how does a batterycharger/shorepower/inverter work? What is needed for me to charge the old and new battery by shorepower?

Is all I need, really just a batterycharger? Hook it up with the two batteries and connect shorepower to the charger and then it takes care of the rest?

I guess that I will need to disconnect my shorepower in order to not continuesly charge the batteries?(I'm sure there's a stop-charge function on most chargers though) - but what if I'm staying in dock and want to run electricity a whole day - do I just use it from the batteries and have the charger continuesly charge it up?

Or let's say I have fully charged batteries and shore power available - can I then run all my boats electricity through shorepower without using my batteries? Or is that where I need an inverter?

Lot of questions, but really trying to figure out how this exactly works and couldn't find anything directly on the subject through google:/

Cheers!
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Old 11-02-2014, 07:55   #2
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Re: Battery charger, shorepower, inverters, WHAT?

The simple answer is that a smart battery charger can be left plugged into shorepower and it will provide current to charge the batteries. All 12V items on board will draw their power from the batteries and/or the charger when it's connected to shorepower. You don't need an inverter to do this.

HOWEVER, it's really more complicated than this, and depends very much on your location, your cruising plans, the electrical equipment onboard, and other factors.

To properly answer your questions we'd need a lot more information.

To begin with, I'd read up a bit on marine electrical setup. To do this well, get yourself a copy of a basic electrical book (like Charlie Wing's book which you can buy at West Marine or order from Amazon). You really need a good reference book like this in order to supplement your readings from online sites.

There's a TON of info online for sure, but as a novice you have no way of knowing what's good advice. That's why a basic electrical book like Wing's is important.

Bill
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Old 11-02-2014, 08:20   #3
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Re: Battery charger, shorepower, inverters, WHAT?

In simple terms, the answer to your question is this:

1. Shore power brings AC power into your boat and distributes it to AC equipment (like immersion heater in your hot water tank) and AC outlets on board. Different boats may be wired in different ways, but rarely do you need any other equipment to use AC power on board via shore power. Just plug it in.

2. Battery charger does just that -- charges your batteries off AC power provided by shore power or by a generator. Will power 12v loads on board when you have shore power connected.

3. Inverter -- produces AC power from battery power. This is very useful when you are at anchor away from shore power, and need AC power for something. Note that the capacity of your battery bank and the size of the inverter needs to correspond to the load you propose to put on it. If you have nothing but one 70 amp/hour battery, you will not be able to run more than a couple hundred watts, if that.

4. Inverter/Charger: this is, as the name suggests, an inverter and charger in one box. It is more than the sum of its parts, however, as most of these have some really cool functions like allowing you to regulate how much power you draw from shore power (or generator), and supplementing limited shore power or generator power with power inverted from your batteries. This can be extremely useful for "shaving peaks" off AC power demand.


That's about it. DC equipment on board (like navigation instruments, lighting, etc.) is powered from the batteries, which are charged not only by your battery charger, but by an alternator on your main engine. Some boats also use solar and/or wind power to charge batteries. The engine start battery is usually separated from the battery bank used for other loads, which brings with it many complexities, like how to charge all of these batteries from one source. The care and feeding of lead/acid batteries is a whole complex subject in itself - reading in the archives will reward you.

Cheers.
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Old 11-02-2014, 08:26   #4
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Re: Battery charger, shorepower, inverters, WHAT?

Hi guys,

Thank you for your very detailed answers. I think I understood everything and I will definitely have a look at the recommended book.

So let's say im at shore and I want to listen to play music through my radio. My batteries are fully charged and shorepower is connected with my batterycharger.

Does the charger then continuesly charge my batteries for the power im consuming?
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Old 11-02-2014, 08:29   #5
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Re: Battery charger, shorepower, inverters, WHAT?

Quote:
Originally Posted by Nickelodeon View Post
Hi guys,

Thank you for your very detailed answers. I think I understood everything and I will definitely have a look at the recommended book.

So let's say im at shore and I want to listen to play music through my radio. My batteries are fully charged and shorepower is connected with my batterycharger.

Does the charger then continuesly charge my batteries for the power im consuming?
Yes. It will do the same for ALL loads, providing that the output of the battery charger is large enough for the loads connected. Otherwise, power will be drawn from BOTH the charger and the batteries.

Bill
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Old 11-02-2014, 08:31   #6
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Re: Battery charger, shorepower, inverters, WHAT?

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Originally Posted by Nickelodeon View Post
Hi guys,

Thank you for your very detailed answers. I think I understood everything and I will definitely have a look at the recommended book.

So let's say im at shore and I want to listen to play music through my radio. My batteries are fully charged and shorepower is connected with my batterycharger.

Does the charger then continuesly charge my batteries for the power im consuming?
If the batteries are fully charged, then the system will be at float voltage, which is not enough voltage to keep putting energy into the batteries. When you put a load on, like turning on lights and/or your radio, the battery charger will increase its output to keep the voltage up to float voltage. So in effect the battery charger will be powering this equipment without the batteries ever feeling the load.

If you put on a load which is greater than the capacity of the charger, then battery power will be used in addition. When you take the load off, the charger will start recharging the batteries with the freed-up capacity.
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Old 11-02-2014, 08:55   #7
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Re: Battery charger, shorepower, inverters, WHAT?

Nickelodeon

What year Vega? Great little boats, but I'm biased

I managed to shoehorn two Trojan T105's under the sole in mine and put one of the existing in the the port cockpit locker as a reserve battery. I charge with a Guest 10 Amp and the stock 50 Amp alt. Lots of power now. I run ST60+ sail instruments, stereo, all LED lights and can easily go two days before before I hit 50% SOC.

After you read up on basic electrical, there are a couple of excellent links here:

1/BOTH/2/OFF Switches Thoughts & Musings - SailboatOwners.com

Electrical Systems 101

And tons of other good advice on this forum.
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Old 11-02-2014, 09:11   #8
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Re: Battery charger, shorepower, inverters, WHAT?

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Originally Posted by glenn.225 View Post
Nickelodeon

What year Vega? Great little boats, but I'm biased

I managed to shoehorn two Trojan T105's under the sole in mine and put one of the existing in the the port cockpit locker as a reserve battery. I charge with a Guest 10 Amp and the stock 50 Amp alt. Lots of power now. I run ST60+ sail instruments, stereo, all LED lights and can easily go two days before before I hit 50% SOC.

After you read up on basic electrical, there are a couple of excellent links here:

1/BOTH/2/OFF Switches Thoughts & Musings - SailboatOwners.com

Electrical Systems 101

And tons of other good advice on this forum.
Hi Glenn,

It's a 73' but in almost mint condition. Will be taking a closer look this week possibly and then hopefully I'll be a boatowner!

I was thinking to either replace the 70Ah with a much larger or go with 2 batteries. It all depends on what I can fit into the Vega. Ideally, the more juice the better, I will be cruising the open sea much, so it would be great for me to blast the stereo for long without having to worry about power.

From my calculations, a stereo with 2 speakers at moderate volume will draw aprox. 40watts an hour??
So fitting at least 150-250Ah worth of batterypower would be ideal. What do you think is possible without compromising weight and space? After all it is a small boat, and I doubt it's suitable for 100kg's worth of batteries?
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Old 11-02-2014, 09:27   #9
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Re: Battery charger, shorepower, inverters, WHAT?

Nickelodeon
Your existing system with 70 amp hour battery is small and not upgraded. It may not have a smart charger but a small automobile type charger. If so and you leave it charging continuously it can cook your battery. That can ruin the battery and be very dangerous. A smart charger is not a big expense as part of an electrical upgrade. Enjoy the Vega. Great boat.

Sent from my LG-P769 using Cruisers Sailing Forum mobile app
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Old 11-02-2014, 09:42   #10
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Re: Battery charger, shorepower, inverters, WHAT?

The Trojan's give me 225 Amps (100 or so usable) at 12V. Good enough for me, now. I don't think a extra battery or two will make that much difference when you consider the amount of other stuff you will be carrying. I think the Vega sinks 1 inch for 700 lbs or something like that. I probably have a half ton aboard.

But next time I need batteries I will be going with LiFePO4. Might be something to consider if your starting fresh. Will cost a bit but everything will be new and should last a long while.
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