Stupid volts/amps/watts/AC/DC question...

[Greenheart]

I'll regret asking this, as soon as anyone answers. But I've a touch of insomnia, so...that's my excuse.

The Honda EU1.0...one of those handy, 'silenced' suitcase-generators...

...rated output is 900w. The AC output is 16 amps at 240 volts, while the DC output is 8 amps at 12 volts...

...but I thought watts = amps x volts? 16 amps x 240 volts is over 3800 watts...four times the gen's maximum.

And why would the same genset only turn out a measly 8 amps at 12 volts? Isn't that 96 watts? Supposing you wanted to run a coffee pot like this one...http://bit.ly/VAvl6y...it needs 12 volts, but uses up to 200 watts. Well, that's more than double the available amps...

...is there an idiot's guide?

Back to sleep...

 

[nimbusgb]

According to the spec sheet the Eu 10i has a '16A socket' but that is the rating not the delivered current.

The ac output is rated at 900W or 4 Amps at 220v.

The 12v output is a secondary output, totally separate to the 220v system. Add the 96w that it puts out to the 900w that the ac side delivers and you see why its sold as a 1000w gennie.

 

[jwilson]

According to the spec sheet the Eu 10i has a '16A socket' but that is the rating not the delivered current.

The ac output is rated at 900W or 4 Amps at 220v.

The 12v output is a secondary output, totally separate to the 220v system. Add the 96w that it puts out to the 900w that the ac side delivers and you see why its sold as a 1000w gennie.

Yes - the 16 amp refers to the caravan/boat type round-pin shorepower/outdoor connector, as opposed to a domestic UK 13 amp square-pin one. Doesn't mean 16 amps comes out of it.

 

[NB Willawaw]

The 12V output is pretty useless on these. The mains output is lovely and pure and will drve virtually all appliances without complaint.
However the EU10 is too small to drive most things on a boat and many people have made the mistake and ended up buying the bigger one in the end.

They also do an LPG conversion.

 

[Greenheart]

Thanks for these explanations. I'll now reinforce my appearance of daftness. Please be kind and keep any answers simple.

I was interested, speculating, if one of these tiny generators could be used to power an electric outboard. Please don't ask why!

But I was inferring from Honda's quoted outputs, that it would be necessary to 'adapt' the 240volt current back to 12v DC, which, dare I say, would mean the 4 amps would increase 20-fold...easily sufficient to drive the trolling motor?

These motors generally require 12 or 24 volts, and consume up to 40 or 50 amps. Isn't that around the 1000w mark, which the Honda EU1.0 could manage?

My point is that the Honda genny's engine produces almost as much power as a small petrol outboard...and notwithstanding losses and inefficiencies in the electricity generation, I would have supposed that enough current is created to run a trolling motor, too...

...but I can't make out how Honda's quoted output can be adapted/modified into what the electric o/b requires.

Please don't bother to suggest I source a petrol outboard instead. My question is speculatory and theoretical.

 

[NB Willawaw]

This is the essence of a diesel electric drive, which is used on many ships. I don't know how much power an electric outboard would use but assuming it was within the capability of the Honda, you would need a battery and power supply type battery charger in between.

I've done this on a 58ft boat but using an LPG Honda and a 48V Lynch motor.

 

[rustybarge]

Thanks for these explanations. I'll now reinforce my appearance of daftness. Please be kind and keep any answers simple.

I was interested, speculating, if one of these tiny generators could be used to power an electric outboard. Please don't ask why!

But I was inferring from Honda's quoted outputs, that it would be necessary to 'adapt' the 240volt current back to 12v DC, which, dare I say, would mean the 4 amps would increase 20-fold...easily sufficient to drive the trolling motor?

These motors generally require 12 or 24 volts, and consume up to 40 or 50 amps. Isn't that around the 1000w mark, which the Honda EU1.0 could manage?

My point is that the Honda genny's engine produces almost as much power as a small petrol outboard...and notwithstanding losses and inefficiencies in the electricity generation, I would have supposed that enough current is created to run a trolling motor, too...

...but I can't make out how Honda's quoted output can be adapted/modified into what the electric o/b requires.

Please don't bother to suggest I source a petrol outboard instead. My question is speculatory and theoretical.

Try googling: fishing, St. Casien lake, Fayence , var, France.

You can rent boats with that very set up, electric OB and genny,....petrol outboards are not allowed on the lake.

 

[Greenheart]

I think I see...Honda genny charges 12v battery, which powers trolling motor. I'm surprised the hybrid set-up can't be arranged so that the power goes straight from its source to the trolling motor...

...but that would still work well; a decent 12v battery would also serve nav lights, VHF, GPS, phone charger, laptop...much better than relying on noisy motive power from an outboard, and then the dismally small electrical output from the o/b's charging coil.

And at 50 dB output at low revs, one could charge the battery in relative peace after using the battery to get off a mooring.

Not as robust as an outboard, and possible more easily stolen, but a nice bit of alternative motive power, if a big enough electric motor is found...

 

[ghostlymoron]

I think I see...Honda genny charges 12v battery, which powers trolling motor. I'm surprised the hybrid set-up can't be arranged so that the power goes straight from its source to the trolling motor...

...but that would still work well; a decent 12v battery would also serve nav lights, VHF, GPS, phone charger, laptop...much better than relying on noisy motive power from an outboard, and then the dismally small electrical output from the o/b's charging coil.

And at 50 dB output at low revs, one could charge the battery in relative peace after using the battery to get off a mooring.

Not as robust as an outboard, and possible more easily stolen, but a nice bit of alternative motive power, if a big enough electric motor is found...

Yes but instead of the noisy outboard you've got a noisy generator.

 

[prv]

Yes but instead of the noisy outboard you've got a noisy generator.

The 1000w suitcase jobs really aren't noisy. A lot of market stalls (and even the odd busker with electric instruments) use them. They putter away under the stall and in a normal street you barely notice them. Quieter than most outboards!

Pete

 

[Greenheart]

The 1000w suitcase jobs really aren't noisy. Quieter than most outboards!

That's exactly my point. Honda quote 52 dB at 25% revs...fine for charging. and critically, the genny can be parked under the foredeck with a door boxing even more sound in...although it'll want careful venting. But you can't put an outboard anywhere except on the transom, and even Honda's quietest 4-strokes are damned noisy at close quarters.

Plus, you can charge offshore when the wind is giving you other things to think about...then enjoy silent thrust inshore later, going up a river. Nice.

 

[rustybarge]

That's exactly my point. Honda quote 52 dB at 25% revs...fine for charging. and critically, the genny can be parked under the foredeck with a door boxing even more sound in...although it'll want careful venting. But you can't put an outboard anywhere except on the transom, and even Honda's quietest 4-strokes are damned noisy at close quarters.

Plus, you can charge offshore when the wind is giving you other things to think about...then enjoy silent thrust inshore later, going up a river. Nice.

+1

Much cheaper than a wind charger or solar cells, and much more reliable.
Eg: the winch fishermen use to haul lobster pots, it's just a little Honda motor driving a hydraulic pump

 

[William_H]

Honda Gen to drive electric o/b

The concept might be quite reasonable.
As said the 12vDC output of the Honda is not much more than a token gesture. It might charge a battery a little but I think the DC voltage would be too low for real charging.
So for real DC power out you need to feed the 240v AC to a charger. Or transformer rectifier unit. This could give you what ever voltage you want from 15v battery charging 13v for running 12v systems or 24 or 48 volts for high powered motor. Just choose the right transformer rectifier or battery charger. You would be looking for something like 60 or 70 amp charger to use all the AC power of the gen.
Or alternatively you could try a 240vAC motor of about 1 HP coupled to your prop shaft.
all cogitations happy new year from olewill

 

[Greenheart]

A pity that petrol outboards aren't given a 'lbs thrust' quoted output. The Minn Kota '101' provides 45kgs of shunt...is that equivalent to a boat being moved by a small woman pressing her bodyweight downward into a loop of its painter, hanging over a quay-rail...?

...sounds rather modest, considering it's the most powerful electric outboard not made in Germany at enormous cost.

 

[Greenheart]

So for real DC power out you need to feed the 240v AC to a charger. Or transformer rectifier unit. This could give you what ever voltage you want from 15v battery charging 13v for running 12v systems or 24 or 48 volts for high powered motor. Just choose the right transformer rectifier or battery charger. You would be looking for something like 60 or 70 amp charger to use all the AC power of the gen.

Useful stuff there, thanks Will.

 

[nimbusgb]

A 12v 75 amp secondary transformer is going to be quite a lump and you'd need some big rectification diodes and a decent smoothing capacitance ( a battery ) but it would work ok.

Unless you are running the motor flat out all the time you could use a decent leisure type battery and a mid sized 40 amp or so charger. The battery would provide the oomph when you do need full throttle and the rest of the time you are only running the gennie at around 50% max so keeping the noise pretty low.

Only go looking for an 80 amp charger if you need full taps all the time.

 

[Heckler]

That's exactly my point. Honda quote 52 dB at 25% revs...fine for charging. and critically, the genny can be parked under the foredeck with a door boxing even more sound in...although it'll want careful venting. But you can't put an outboard anywhere except on the transom, and even Honda's quietest 4-strokes are damned noisy at close quarters.

Plus, you can charge offshore when the wind is giving you other things to think about...then enjoy silent thrust inshore later, going up a river. Nice.

One HP is equivalent to 750 watts? ISH! Do we think that a suit case 900 watt genny is going to drive any decent sized boat?
Stu

 

[Greenheart]

One HP is equivalent to 750 watts? ISH! Do we think that a suit case 900 watt genny is going to drive any decent sized boat?
Stu

Who said anything about 'decent-sized'? Didn't you know that 750w is close to a horsepower?

 

[Heckler]

Who said anything about 'decent-sized'? Didn't you know that 750w is close to a horsepower?

i couldnt be arsed looking up the exact figure, iirc its 734
stu

 

[Greenheart]

Near enough for my purposes.

I know 1hp isn't much...but I was thinking that as a cruising dinghy would ideally carry many of the systems a yacht uses, it will need a 12v supply...and that will need charging. Why not have a gen, and use elec for prop-turning too? Only for berthing/canal work...