Generator for battery charger

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jonlea

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I have a Sea Ray 270 with three 110ah batteries and a 3litre diesel engine which requires the batteries to be in peak condition to start. The charger fitted is an American (Newmar Phaser – no information available??). I am considering purchasing a small petrol 240v generator to use as a backup to run the battery charger when I don't have electricity available (eg Newtown Creek overnight). What wattage generator would I need to be able to do this successfully?
 
The smallest lightest one you can find will do the job unless your charger is much bigger than average. A 25 amp charger, putting out 14 volts to charge a 12 volt battery bank is only producing 350 watts. On the mains side it will draw more than that, but a charger with a 1KW output would be sufficient for a 50 amp charger.
Some generators have a 12 volt output to charge batteries directly, but that is a very poor alternative to using the mains voltage output via your own battery charger.
I trust that your battery bank is switched so that the engine start battery is not being disharged by domestic power use.
 
I hope you are right about the later point - I must check that out. The USA built in battery charger only goes up to about 10 amps max so I assume from what you are saying a generator like the Wolf 950 (max output 720w and continous 60wats) would be okay - there is an advert in the Express today for this model at £79.99.
 
If you need the generator/charger just for an overnight stay (unless you are loading the engine start battery overnight?) then there is something pretty fundamentally wrong with either the design of your system or the components.
 
B&Q have been selling a model pretty well identical to the Wolf for about £50. Both are 2 strokes, and for about £100 you can get a much better 4 stroke, though it is heavier and built in a steel frame. The Honda 4 stroke suitcase style generators are good and a bit quieter, but expensive. For a cheaper alternative check out Kipor generators. They make small quiet suitcase generastors, the lightest 720 watt model weighs only 10KG, the 1000 watt model is about 14KG.
 
Of course it all depends on your usepattern but as suggested you should be able to go for many weeks without charge without worrying about the engine battery starting the engine. You might simply do well to buy a new engine start battery (they don't last forever) or do well by fitting another engine start battery in paralell. This will give you a lot better starting current. (clearly what you really need is a 24volt engine battery system but don't go their yet)
good luck olewill
 
Just to nip in on the tail end of this thread. I have one of those B&Q cheapos. It has served well over the last 2 years.
My domestic bank is 240 amp hours and my starter battery is 100 amp hours. I like to think that in an emergency I could charge up either set of batteries using the genny and a mains charger. My present charger is rated up to 10 amps but usually seems to charge at a max of 6. I guess from what I read that I could get a halfords charger rated at 25 amps and run this off the genny.
I have seen the bigger genny at B&Q, I didnt realise it was 4 stroke, would it be quieter? I must admit, though that the small cheapo is easilly manhandled on and off the boat and into lockers etc.
Regards to all.
 
I would be very wary about connecting one of the cheapo generators of the B&Q variety to anything "electronic" - That would include 4 step mains chargers and anything with a "chip" or "chips" in it.

I had bought one of the B&Q gennys but noticed a warning in the manual not to connect anything electronic to it so I contacted the techie folk at the manufacturers and they confirmed that it was not recommended as the output was not that clean and the voltage spikes could damage "sensitive" items. The techie folk went on to define "sensitive" as anything with a "chip" in it.

Now I don't know what charger you have but do bear teh above in mind. My mains charger is a 60 amp 4 step jobby which cost too many beer tokens so I returned the B&Q genny and eventually bought a Kipor (pure sine wave and "clean") - I would not take the risk of buggering up the charger (or the TV or DVD or microwave).

Your charger, your boat, your call......
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Look at your batteries, charging and switching.

The engine start battery should be clean, dry, topped up correctly, be rated with the CCA (or MCA) specified by the engine manufacturer, be charged all the time the engine is running, and always be in peak condition given reasonably regular use.

The other two should be designed for domestic duties (ie deep discharge) and should be selected and charged via a switch or splitter 'mechanism' that avoids the starter battery incurring domestic loads.

Sounds like the battery management is lacking.
 
The quietest possible if you're going to run it at anchor in Newtown please - and acknowledgement of the etiquette of only running for charging in the forenoon too /forums/images/graemlins/tongue.gif
 
Generators are really not very appropriate for charging batteries - which requires small power output for a prolonged period of time. However those with a 12V output can be used very effectively to augment the output from the battery while trying to start the engine (rather like Jump starting a car).

However it shouldn't take 3 110Ah batteries in peak condition to start a 3L engine. I would suggest that you look at your set up and fit a dedicated engine start battery (which should be rated in CCAs rather than Ah).
 
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