How long to charge battery with Honda Genny

[ghostlymoron]

I know it's a bit like 'how long is a piece of string' but, assuming genny like this http://www.justgenerators.co.uk/pages/HondaEU20i.htm and 100Ahr battery. Rated output 1600w, so at 12v, amps = 1600/12= 133a
So to charge 100Ahr from 50% to 80%. t=100x(.8-.5)/133 = 13mins
I suspect it is not that simple.

 

[neale]

The 12v outlet will probably be rated at something like 8 amps. Might be better to use a decent 240 volt charger providing something like 20 amps.

 

[rogerthebodger]

The 12DC out put from that generator or the similar one I have will never charge a 12 battery as you need something like 13.8 volts to get any kind of charge in.

Connect a 3 stage mains charger and it would work OK. I use my 1000w honda with a 50A mains 3 stage sometimes when there is no sun to use my solar panels

 

[VicS]

I know it's a bit like 'how long is a piece of string' but, assuming genny like this http://www.justgenerators.co.uk/pages/HondaEU20i.htm and 100Ahr battery. Rated output 1600w, so at 12v, amps = 1600/12= 133a
So to charge 100Ahr from 50% to 80%. t=100x(.8-.5)/133 = 13mins
I suspect it is not that simple.

No not that simple.

If you are thinking of using the 12 volt outlet I think you will find the rating is, as neale suggests, relatively modest ... it may not even be suitable for battery charging. It may be 12 volts not the 14 or so you'd require. Some generators do have an output specifically for the purpose though.

I'd suggest you check the full specs on the manufacturers website, and even down load the manual, for any generator you are considering.

However as neale also suggests the better alternative is probably to run a good automatic charger from the 230 volt output. It also gives you the versatility of charging from a shorepower supply when that's available.

Edit: In short what Roger says

 

[duncan99210]

The 12DC out put from that generator or the similar one I have will never charge a 12 battery as you need something like 13.8 volts to get any kind of charge in.

Connect a 3 stage mains charger and it would work OK. I use my 1000w honda with a 50A mains 3 stage sometimes when there is no sun to use my solar panels

+1. I use an 800 watt gen set with my 40 amp smart charger when the sun isn't co-operating and that puts enough back in to keep things going.

 

[macd]

I know it's a bit like 'how long is a piece of string' but, assuming genny like this http://www.justgenerators.co.uk/pages/HondaEU20i.htm and 100Ahr battery. Rated output 1600w, so at 12v, amps = 1600/12= 133a
So to charge 100Ahr from 50% to 80%. t=100x(.8-.5)/133 = 13mins
I suspect it is not that simple.

The posts above about the dedicated 12V output are quite right. It will only deliver something like 8A and probably not at the voltage your batteries require to charge. But look on the bright side: the cables you'd need to run 133A to the batteries would cost (and weigh) quite a lot.

Even using the 240V output to run a charger the sums, as you feared, are not so simple. The battery condition you describe requires 30Ah to reach 80% charge, 50Ah to reach 100%. A 40A charger may initially pump in 40A, but this would decline as the battery charged. As a very rough guess, it may put in 30Ah in an hour or so, bringing the battery to 80% in that time. The remaining 20%/20Ah will take considerably longer.

13 minutes does sound wonderfully attractive, though. We wish

 

[marcot]

What if you run your 220v cable from the 220v genny output to the boat charger?

 

[ctva]

I bought the 1.0EUi Honda last year (or was it the year before.... old age) and never considered the 12v outpot as it's there to run 12v appliances. Most efficient way as others have said is to power the mains charger, either a built in one, I've got a Sterling 20amp with a 240amp domestic and 75amp engine battery, or a portable car charger. Either way, for normal use over two or three weeks mix of sailing / motoring / anchoring I've found that I need to charge for a couple of hours every couple of days. We do run a fridge 24/7 and the raido but not a lot else.