Battery charging with generator

[Apetts]

Anyone have experience of charging batteries with a small petrol generator? Are
there any probles involved in charging a 200ah battery from the 12V, 8amp generator output? Is it possible to use the 250v 2.4amp output linked into the boats ring main and use the boats 30amp inbuilt charger?

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[Paulka]

I routinely use the Honda generator to charge the batteries via 240v. distribution and 30 A charger.

Never experienced problem, thus never tryied to charge via the 12v circuit. It is certainly possible, althought the 8 A sounds a little weak.

Good luck.

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[snowleopard]

charging from a generator via the shorepower charging circuit is fine with two provisos:

1. make sure you have enough power in your generator on continuous output to cope with the demands of the charger, for example a 30A charger needs at least 700W output and other charge rates pro rata.

2. don't connect the charger until the generator is running and up to speed; the load during startup may wreck the generator.

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[richardandtracy]

Also a 2.4Amp@250V (600W) genny isn't usually rated continuously at this load, it's more likely to be 2Amp@250V continuous (ie 500W). Don't be too surprised if it suddenly stops on you, having overheated. [Been there, done that with a 3KVA genny & a 160A welder. I ended up putting a small car radiator in the generator's oil circuit for extra cooling - made just enough difference.]


Regards

Richard.


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[bernard_foster]

I often use my Clarke 700w genny to charge my large capacity boat batteries (originally tractor batteries), without problem, however when i use my brothers higher capacity Genny it keeps tripping out under the load, so to some depends on the circuitry in the genny, my one puts out 8.5 amps on 12V

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[Alex_Blackwood]

Sorry, am I being a bit slow here? How do you make a 12 volt 30amp charger take 700 watts? I make that 360 watts and if the genny is rated at 230 volts the charger will draw about 1.6 amps. It will probably be a little more with volt drop etc. but will be no more than 2 amps max.
If it is only a 500 watt continuously rated machine you wont have any spare power to run anything else but it should charge the batteries OK.

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[mica]

Hi there,

We have recently bought a Honda Petrol Generator and plug the 240v into the shore power circuit which charges the batteries through the on board battery charger, but we also use a long lead from the 8amp socket on the generator and plug it into a cigarette lighter socket on the boat, which helps provide a bit more umph going into the batteries.

May as well use all the power the generator gives whilst you are running it.

MICA

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[snowleopard]

here\'s the arithmetic

straight from the horse's mouth (charles sterling of charger fame)

1. you don't charge at 12 volts but at 14.8

2. the charger is not 100% efficient but more like 65%

14.8v x 30A = 444w output

with 35% efficiency losses this requires 444 x 100 / 65 = 683w input

which is pretty marginal for generators producing a nominal 720w output or thereabouts.



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[spark]

Honda suitcase genny and Mastervolt charger

Paulka, Mica, and anyone else...

What model of Honda genny are you using and what make/model of battery charger?

I am looking into the compatability of a Honda EU20i (suitcase) genny and a Mastervolt Mass charger.

Richard at Mastervolt UK says that their Dutch head office is doing tests at the moment, plugging petrol portable gennies into their chargers, but he does not yet have the results and cannot, therefore, recommend the practice (despite their brochure saying it is OK).

If I can find someone already doing this with a Mastervolt Mass charger it will speed up the decision making.


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[Paulka]

Re: Honda suitcase genny and Mastervolt charger

My generaor is a very old (bought second hand in 1981) Honda 450 W.
My charger is a Victron 30 A.
My 240 ~V "net" is fed via one DCB then one each MCB for the charger and one socket.
I use the same plug to feed my 240v "circuit" from either the marina's main, or the generator, when at anchor.

I am fully aware that the earth wire is useless when feeding from the generator, as it is at best connected to the carcass of the generator.
BTW I never checked if the N is connected to the carcass or to the E! ???!!! It probably is NOT.

I feel this situation is acceptable on a non metalic boat.

Hope this help.

Paul

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[spark]

Re: Honda suitcase genny and Mastervolt charger

Thanks Paul. It does help a bit.

The word from Holland is that a petrol genny connected to a Mastervolt IVO or Dakar model of charger does work OK with the caveat that if the genny slows down (for whatever reason) below a certain (unquantified) speed the charger 'may' be damaged (I think the issue is the frequency of the AC coming out of the genny rather than the voltage).

The recommendation is to disconnect/switch off the charger before stopping the genny.

I'm told that the Mass chargers are very similar to the IVO ones so I 'should' be alright.

I told Richard about your system and he says the Victron chargers are very similar to the Mass ones, which adds to the peace of mind.



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[mldpt]

IN June I competed in the three peaks yacht race from Barmouth to Fort William and a great time we had, But motoring out to the start my alternator packed up, we had a fridge full of freah food ro the whole trip, stupid really as we had loads of time to shop at each stop over while the runners were doing their bit. I used my genny 700W for the whole trip and back to Fleetwood fortunatly the weather was hot, calm and windless so it stayed on deck the whole trip and kept the batteries well charged useing the 240v and onboard mains charger, but my charger doesnt seem to charge at more then 15A but I have not used the 12V output as if it is only rated at 12V then surely it wont charge a 12V battery. There has been mention of the earth wire on the genny, I am not sure about this side of it but , when I connected mine up to theshore line plug the first time I get a polarity warning, an friend told me to connect the earth in the plug to the Boat supply to the Neg and to remve the earth on the plug out of the genny. Does this sound OK this does stop the polarity problem, but if I switch on the domestic sockets in the boat the polarity light comes on. I havnt switched on the emersion heater as I think its 1000w and would stop the genny. so we had cold water all the way to Fort william but it was great fun sailing all that way with out an engine. we did have a pair of sweeps which we used on several occasions, the boat a Westerly corsair 7+ tons. www.sailingforfun.co.uk Regards Mike

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