Batteries or small generator?

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Sea Lion

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Hi all

Just had a fantastic weekend in herm in the CI, however we ended up draining the domestic battery. Not to worry as we had a separate starter one so we could still get home. This led me to think about our batteries and current requirements as there were a number of boats with small Honda petrol generators on the bathing platforms in herm this weekend.

We have 2x140 amp hr batteries one for domestic and one for starting and the bow thruster. Both fully charged and in good condition. Over the weekend we only had a 12v cooler running (no idea what the draw was) for around 10 hours, the water pump intermittently for dishes and 4 quick showers, radio for 4 hrs and the odd cabin light for the evening. Without doing the maths I had hoped the domestic battery was sufficient, but obviously not.

Just wondering what other people's experiences are with similar banks/usage and if anyone has a portable generator if it's worth investing the £600 or so to get one. Would it be able to plug straight into my shore power plug and charge the batteries via the smart charger?

Thanks

Benn
 
I had 3x115 ah domestic batts on Rafiki. This was fine for overnighting, running fridge/lights/TV/kettle/microwave. Needed to top up from the engines next day. Worked fine. Had separate starter batts for the engines/thruster/winch.
 
No expert but...... A weekend is 48hrs? 140ahr battery will give you about 70ahrs of useful juice. If you're drawing anything much over 1.5 amp on average your battery will be flat.
 
As a rule of thumb only 50% of the nominal capacity is useable.

Assuming your cooler will be around 50-60w that is approx 5 amps at 12v, so drawing 5AH for 12 hours, plus occasional loads that's your 70 AH useable power.

I would go for a small say 600 w genny, with two 140 AH matched for the domestics, with a separate starter battery rated around 110AH, but with high CCA. The genny gives you back up to quickly charge the batteries if you overdo it.

Connecting the genny via the shore power connection requires a simple cable adaptor.
 
Your cooler is the killer. If the most you do is weekend find a supplier of block ice and set up a cooler to take that. It should do three days with ease.

Generators and noise. The gold standard of portables is the Honda suitcase but even they produce noise and smelly fumes both of which spoil the enjoyment of a peaceful anchorage.

Have you space somewhere for 80 watts or so of solar? It won't keep up with your power needs running the cooler but it with a full charged battery is should keep you going over the weekend. About £140 off fleabay.
 
If you go down the generator route, get the largest you can justify. I would suggest at least a 1kw but preferably a 1.5 or 2Kw unit. Once you've got one you'll start to find other uses for it and a 600w might be a little restrictive running certain things.
Even the suitcase Honda's still knock out a fair bit of sound so you might find then a little annoying, but I'm sure you can run them somewhere quite, as said above, somewhere well ventilated.
 
Unless you are gong for a full installation with properly silenced water injected exhaust system, having a larger generator you then rely on will ruin the quiet anchorage you (& others !) are seeking. Hence my advice just to use a smaller genny occasionally and discreetly to provide starting back up.

If you want hot water use a gas kettle.
 
Lantic Lass said:
Be very very careful with generators,that they are vented extremely well,quite a few people have died when not vented properly.
Click to expand...

+1
It pays to be paranoid about fumes IMHO. Even on the bathing platform there can be a problem if the wind is in the wrong direction. Take great care if you get a portable gennie.
 
Just read superheat6k's reply and it reminded me that I use a couple of battery LED light bars on the boat, ebay ID 390584016100. They seem to last forever but do charge when the engine is running. Just a simple way to have good lighting without worrying about running down batteries. Just food for thought.....
 
With one 110Ah battery and one small fridge we can stop 24 hours comfortably but we tend to be economical with use of lighting and dont leave the fridge door open for a moment more than necessary.
We have stopped longer but it soon becomes apparent that the battery is getting low.

Can your boat accommodate an additional leisure battery ? If so I think that might be the best plan.
 
Sheppy said:
Just read superheat6k's reply and it reminded me that I use a couple of battery LED light bars on the boat, ebay ID 390584016100. They seem to last forever but do charge when the engine is running. Just a simple way to have good lighting without worrying about running down batteries. Just food for thought.....
Click to expand...
Www.bedazzled.co.uk is also good for LED lighting, with a wide range of sizes and adaptors.
 
I was in Herm from Friday to Sunday. I too had problems with my Batteries as the week before I had not been to the boat and had left the main battery switch on , which also powers the gas alarm,so by Saturday night I had red battery condition indication on the main starter bank. Quickly solved by running the engine when the tide came in, and a run to Guernsey early Sunday to pick up a few people.
The guy with the Fairline Targa 29 at the top of the beach, had nt floated for 4 or 5 days and had a very neat Honda Generator on the dive platform, that from 10 m away you could nt hear running, but someone else had one that was quite noisey.
Whatever you choose, you may annoy someone, but as Rob , Lantic Lass says, keep it safe, We are all in the same boat so to speak, and when you can t get to shore power, whatever Batteries you have, careful use of the power you have is a must.
Great weekend in Herm though, I will probably be back there next weekend, but will book a table at the Ship, as although the Mermaid menu is good. The menu at the Ship looked more to my taste, and have eaten all I fancied off the Mermaid menu, and drunk all the beer as I was saving the batteries...:rolleyes:
 
Thanks for all the comments. I don't think solar will work having used it previously on yachts it doesn't deliver in the uk. I will investigate what the cooler does draw. It's a simple plug and play from the marine store rather then the boats fridge. Strangely enough I've never got the actual fridge to work even on shore power.

For those using small generators do they manage to charge batteries relatively quickly. Wouldn't want to have a gene running for hrs in a small harbour, it would start to sound like a fair ground!
 
Sea Lion said:
Thanks for all the comments. I don't think solar will work having used it previously on yachts it doesn't deliver in the uk. I will investigate what the cooler does draw. It's a simple plug and play from the marine store rather then the boats fridge. Strangely enough I've never got the actual fridge to work even on shore power.

For those using small generators do they manage to charge batteries relatively quickly. Wouldn't want to have a gene running for hrs in a small harbour, it would start to sound like a fair ground!
Click to expand...
A typical 30 amp charger will draw 30 x 12 x 1.1 = 400 watts. The charging rate will therefore depend upon your charger rather than the genny. Most dual output chargers are smaller than this. 30 AH will probably take around 3 hours to put 70AH back into your battery, as charging is not an efficient process.
 
Sea Lion said:
Thanks for all the comments. I don't think solar will work having used it previously on yachts it doesn't deliver in the uk. I will investigate what the cooler does draw. It's a simple plug and play from the marine store rather then the boats fridge. Strangely enough I've never got the actual fridge to work even on shore power.

For those using small generators do they manage to charge batteries relatively quickly. Wouldn't want to have a gene running for hrs in a small harbour, it would start to sound like a fair ground!
Click to expand...
You already have the best charger built in to your boat, the alternator on the engine, which will charge much quicker than a small gennie, and will also heat your calorifier.
 
Sea Lion said:
Hi all

Just had a fantastic weekend in herm in the CI, however we ended up draining the domestic battery. Not to worry as we had a separate starter one so we could still get home. This led me to think about our batteries and current requirements as there were a number of boats with small Honda petrol generators on the bathing platforms in herm this weekend.

We have 2x140 amp hr batteries one for domestic and one for starting and the bow thruster. Both fully charged and in good condition. Over the weekend we only had a 12v cooler running (no idea what the draw was) for around 10 hours, the water pump intermittently for dishes and 4 quick showers, radio for 4 hrs and the odd cabin light for the evening. Without doing the maths I had hoped the domestic battery was sufficient, but obviously not.

Just wondering what other people's experiences are with similar banks/usage and if anyone has a portable generator if it's worth investing the £600 or so to get one. Would it be able to plug straight into my shore power plug and charge the batteries via the smart charger?

Thanks

Benn
Click to expand...

Firstly, what kind of boat? have you got an engine? With an alternator? Does it charge the batteries when running?

Secondly... Consider using your 2 x 140Ah batteries for domestic, and getting a smaller, high CCA, starter battery.

Thirdly.... If you get a generator, which will provide 240V to power your battery charger via your shore power connector, how many Amps is the charger - this will guide you in your choice of generator.

Fourthly.... Perhaps we'll get to that when we know the above :)
 
Richard10002 said:
Firstly, what kind of boat? have you got an engine? With an alternator? Does it charge the batteries when running?

Secondly... Consider using your 2 x 140Ah batteries for domestic, and getting a smaller, high CCA, starter battery.

Thirdly.... If you get a generator, which will provide 240V to power your battery charger via your shore power connector, how many Amps is the charger - this will guide you in your choice of generator.

Fourthly.... Perhaps we'll get to that when we know the above :)
Click to expand...

Here goes

The boats a rodman 800. With vp kamd 300. Yes charges batteries but for our running probably an hour or two at a time I doubt it will ever fully charge the batteries

2 not previously but will now. The engine compartment has a dedicated two battery box on a fixed shelf. To add to the bank I will extend the shelf and add a new or bigger box

3 will have to lo at the manual. Will pop to the boat tomorrow to check it out

4 ?

Cheers

Benn
 
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