What are my charging options?

jcwads

jcwads

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Hi All

Sure this has been covered before but I am planning a 2 week cruise on my 27ft MOBO down to Cornwall. I am looking at my options regarding charging the batteries when not in a marina. I would like a few days on mooring buoys.

Given that I will want to use the electrics for the fridge, lights at night if needed, pumps etc etc, I dont want the batteries to go flat. So do I buy a little Honda EU10i to charge via by AC shorepower which would activate my battery charger?

Does anyone have experience on how long I could run the DC power for (fridge, pumps etc) before I have no juice left..

Are there other alternatives? It would be great to be in a position where I am not paranoid about having no battery power!!!
 
You need to do an audit of your electrical consumption by finding out the consumption of individual items times the number of hours you expect to use them. This gives you an AH figure that you can compare with your capacity. Batteries are best if they don't go below 50% capacity. So if your hourly consumption is 10 amps and your battery 100AH you have 5 hours safe capacity with a fully charged battery and possibly up to 7.

To be safe you should have a dedicated engine start battery so you can always start your engine and a house bank with enough capacity to cater for your expected domestic use. A split charging system will also make sure your start battery is always fully charged.

You can of course use a portable generator but they are noisy, consume petrol, give out fumes and you need to be really careful how you use them on a small boat like yours - as well as avoiding upsetting your neighbours with the racket.
 
Whilst this is not at all scientific batteries will typically last you about a day including refrigeration.

Now of course if there are massive batteries they will last longer but the factory spec of the boats I have had all seem to give about a day. The odds of 2 days are low in my view. Running the engine for an hour in the morning and evening is probably the cheapest and simplest solution and will give you a half decent top up

A portable generator means noise , petrol on board and cost to buy it
 
Assuming that your engine(s) will charge the batteries, you only need to cover the times when the engine(s) aren't running ot when you are not on shore power.
Thats stating the obvious - of course.

In my experience, it is the fridges that are the biggest concern when it comes to battery drain.
Virtually everything else can be switched off.
Maybe get an LED anchor light.
Although I'm not sure that is necessary if you are going on a buoy - we always show an anchor light - even when we are on a buoy.

OK - so the fridge is the biggest drain - maybe look at if you actually need it - eating out etc.
Maybe only run the fridge when the engine is running.

You don't say much about your batteries - do you have a separate battery for the engine?
But if you are going to rely on the batteries and you want to recharge them using a portable generator - please, please, please be careful.
The exhaust gasses are lethal and heavier than air - make sure the generator is in a well ventilated space and don't run it whilst you are asleep in bed.
Maybe extra battery capacity would be e better/safer investment than a portable generator.
On a 27 foot boat, you probably haven't got enough space to charge batteries form solar panels and my experience of wind generators is that they are less powerful than solar.

So, to recap.
Try and reduce your battery load and see if that is enough until you can next run the engine(s) or plug into a shore supply.
Finally, a very important thing to consider - batteries take a very long time to fully charge back to the level that you started to discharge them.
 
Thanks for your comments so far.

It sounds like running the engine for an hour am and pm will suffice.

I have 2 batteries but they are linked together so I assume that they share one another's charge.

I am also not overly happy about a generator and I can spend the money on a tender instead :encouragement:
 
jcwads said:
Thanks for your comments so far.

It sounds like running the engine for an hour am and pm will suffice.
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Yep - probably a good strategy.
However - be aware that an hour's charging, even from the engine, won't be enough to "put back" what you have "taken out".
This is exactly my problem.
Batteries take the most charge, form whatever is charging them, when they are empty.
The charge "tapers off" exponentially - i.e. you need many hours to put back what you have taken out.
However, from experience, you can manage using this "fast bulk charge" strategy for a few days without damaging the batteries.
Any more than (say) 4 or 5 days and you will need to arrange a fuller charge (perhaps a long journey with the engine charging for a longer period of time would be enough).
In my experience, using this strategy, the overall charge level drops over this period of time and you can't then get enough back in to last the day - i.e. it would need a longer charging period for them to recover.

You also say that your batteries are linked together so don't run them down or you won't be able to start your engine.
 
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We don't have a fridge in our sailing boat, or shore power. But we do like cold beer and wine and to keep food, particularly​ raw meat, cool.

We have an integral cold box which we keep cool with ice. The best ice is solid so we start off a cruise with several frozen bottles of water, topping up with fresh ice when we can. We use about a couple of kg every day on average.

So, if you have the space in your fridge, why not put one or two bags of ice in it when you can, and turn it off when the engine isn't running? It will melt so you might want to put it inside a container that will catch the water.
 
I have 2 batteries but they are linked together so I assume that they share one another's charge.

As others have said - you really need to keep your starter battery isolated from any consumption for lighting etc. (and also ideally something available to power a VHF?). Also to avoid the flat battery > can't start > can't recharge catch 22. Do you have a switch allowing you to select / isolate the two batteries? Are they both deep cycle or is one a starter or dual battery? Worth knowing as this will affect your strategy for using them.
 
The briefcase Honda EUi10 you have mentioned is pretty silent as compared to many generators . I have one myself and when it is running strapped to the swim platform , you can not hear it if sitting on the bow of the boat.
Running the gen for a couple of hours every day will recharge your batteries and referees your fridge freezer.
Make sure you buy a carbon monoxide alarm and place this in the living quarters of your boat.
I would shout down the fridge I I were you and only run it when the boat motor or gen is running.
 
On our 25ft boat we have two dedicated domestic batteries as well as the starter battery.

We can stay in the same place for two days without the need to run the engine before the domestic batteries drop below 50% state of charge. This includes using the fridge (which we leave on full 24/7), lights (which are all LED), electric kettle (low wattage), pumps, radio, TV, etc and we are not especially careful with our power consumption. We could probably extent that if necessary but we rarely tend to stay anywhere for more then a couple of days.

If we are cruising a decent distance each day (2-3 hours) then we don't have to worry about battery power at all.

We set off on a two week break to Scotland next week and we don't intend to plug into shore power during that break apart from the first night in Inverness Marina to make sure we are setting off with batteries that are 100% charged.
 
If moored on a buoy you should not consider a portable petrol generator (which would presumably have to stand on the bathing platform). The reason being high risk CO poisoning from the exhaust fumes.
Running the engine an hour or so is not good for the engine but will help a little. If the engine is petrol there is also a CO poisoning risk.
I would say 3 hours engine running per battery is required to fully recharge.

The fridge is the main demand on power . I am considering buying a new fridge if it can be proven to be more energy efficient.
As said about 24 hrs stopped per battery is to be anticipated. LED lighting makes a huge difference but ultimately it's the fridge that draws down the batteries.
 
I agree with all of the above that the answer to the OP's problem is to reduce consumption. LED lighting is essential but I wonder if the fridge power consumption could be reduced by filling the freezer compartment with freezer blocks (frozen when on shore power) and gradually moving these to the main compartment when on battery.
 
petem said:
I agree with all of the above that the answer to the OP's problem is to reduce consumption. LED lighting is essential but I wonder if the fridge power consumption could be reduced by filling the freezer compartment with freezer blocks (frozen when on shore power) and gradually moving these to the main compartment when on battery.
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Spot on idea! That will certainly solve it! Hadn't thought of that, but that's perfect.

With the lighting, I assume I dont have LED as my boat is a 2008 american sports cruiser. Is this a simple upgrade?
 
jcwads said:
Spot on idea! That will certainly solve it! Hadn't thought of that, but that's perfect.

With the lighting, I assume I dont have LED as my boat is a 2008 american sports cruiser. Is this a simple upgrade?
Click to expand...

LED's are a simple fix (they're almost certainly G4 bulbs). I can sell you some expensive / top quality LED's or you can buy cheaper alternatives from http://www.bedazzled.uk.com/. Next time you're on board measure the internal dimensions of the light fitting so that you can order bulbs that fit.
 
jcwads said:
Spot on idea! That will certainly solve it! Hadn't thought of that, but that's perfect.

With the lighting, I assume I dont have LED as my boat is a 2008 american sports cruiser. Is this a simple upgrade?
Click to expand...

Easy, simple and cheap.

A no brainer really.
 
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