ianc1200
Well-Known Member
Many thanks for that - now ordered.
Small petrol generator
- Thread starter ianc1200
- Start date
Many thanks for that - now ordered.
wonkywinch
Well-Known Member
From that link - "With the added benefit of a 'fuel valve shut off position', you can keep the engine running without adding more petrol."
How does that work then?
colhel
Well-Known Member
So you can burn off fuel in the carburetor
Bouba
Well-Known Member
In my day they were only 2000W......that’s progress for you
PaulRainbow
Well-Known Member
I don't think running a generator on a 38ft twin engine mobo is a good choice, sorry Ian.
First, 240Ah of leisure batteries is woefully inadequate. As Tranona said, double it, or consider Lithium, 240Ah of lead acid gives a usable 120Ah (if the batteries are new) whereas a 280Ah Lithium pack give a comfortable 140Ah. It also takes up half the space and is half the weight. Another big benefit of Lithium is the fast charge rate.
Secondly, optimise the engine charging. Make sure that the alternators aren't connected to old diode packs, with voltage drop. If the are, a couple of Victron Argofets would improve charging.
You say you've been disappointed with solar, i wonder why. I lived aboard a sailboat for several years with 200W of solar and was self sufficient with power during the Summer, except for cooking and water heating. A couple of 100W panels, discretely mounted, putting out more amps than the genny would, all day, and i doubt you'd ever used the genny.
First, 240Ah of leisure batteries is woefully inadequate. As Tranona said, double it, or consider Lithium, 240Ah of lead acid gives a usable 120Ah (if the batteries are new) whereas a 280Ah Lithium pack give a comfortable 140Ah. It also takes up half the space and is half the weight. Another big benefit of Lithium is the fast charge rate.
Secondly, optimise the engine charging. Make sure that the alternators aren't connected to old diode packs, with voltage drop. If the are, a couple of Victron Argofets would improve charging.
You say you've been disappointed with solar, i wonder why. I lived aboard a sailboat for several years with 200W of solar and was self sufficient with power during the Summer, except for cooking and water heating. A couple of 100W panels, discretely mounted, putting out more amps than the genny would, all day, and i doubt you'd ever used the genny.
ithet
Well-Known Member
I inherited a Honda EM500 - max 500W at 60Hz (400W @50Hz). It works fine even though it was stored for 20yrs, and is reasonably quiet. I have wondered if it would be OK to connect via AC to shorepower to run my Victron BlueSmart IP67 25A charger? I.e. I would not want to damage the charger!
BTW is see those new 2200W Honda units only have the same DC output of 8A as my old 500W unit.
westernman
Well-Known Member
or marketing???
jct1981
Well-Known Member
I'm not an expert at all, but a happy user who understands a small amount. One thing to consider is the 'cleanliness' of the output: does your EM500 output a pure sine wave? Some electronics (coffee machines, laptops) do require this pure sine wave, which not all generators produce; some produce a modified sine wave. You will want to check the BlueSmart requirements to see if it needs this.
I know the EU22i does, so I don't have to think about it.
Hopefully others will be along with a more detailed/accurate/sensible answer!
ithet
Well-Known Member
I would assume it is a decent sign wave, but I am not an expert either, and this is what I was asking. But I am talking about using the AC O/P which is supplied un-rectified via the generator's alternator, so should be OK? The DC output would be quite different, as it is just a simple bridge rectifier. There is no switch mode transformer in this unit as far as I know ( I can post a circuit diagram).
Bouba
Well-Known Member
The pure sine wave is one of the reasons I opted for Honda....but I am not sure about how much is hype...while sensitive electronics say they need pure sine waves...do they actually get toasted if they don’t 
westernman
Well-Known Member
My electric toothbrush got toasted on the boat with a pseudo sine wave inverter.The pure sine wave is one of the reasons I opted for Honda....but I am not sure about how much is hype...while sensitive electronics say they need pure sine waves...do they actually get toasted if they don’t
Replaced several times and toasted again.
wonkywinch
Well-Known Member
Yes, they will. A lot of electronics uses switch mode power supplies and these are very sensitive to the quality of the incoming "mains".The pure sine wave is one of the reasons I opted for Honda....but I am not sure about how much is hype...while sensitive electronics say they need pure sine waves...do they actually get toasted if they don’t
ithet
Well-Known Member
The pure sine wave is one of the reasons I opted for Honda....but I am not sure about how much is hype...while sensitive electronics say they need pure sine waves...do they actually get toasted if they don’t
I see from the EU22i spec that it does indeed have an invertor output. Is this a better way of going AC-AC at generator levels, than just a transformer (Honda say it is to reduce possibility of voltage spikes)?
Is my (non-expert) assumption that my old genny will produce a pure sign-wave from its transformer (I believe) AC output, correct?
Boaty_Pete
New Member
To produce a pure sine wave requires some competent electronic circuitry.
Any generator manufacturer is going to make it very clear they have included that upgrade, to support the appropriate upgrade in cost.
It's highly unlikely an old portable generator is 'pure' signwave but if it is, it would be a surprise to not have it made clear on the labeling/decals.
If there's a specific job for a genny that doesn't req pure, then that's cool. If you want a genny, for just-in-case, the pure signwave makes sense as you can just get on without wondering about the possibility of damage, regardless of whatever usage requirement pops up.
Most modern quality electronics will likely be protected enough to cope via onboard power supply circuitry, but not all.
Any cheap stuff will only have cheap competents, and no protection or sophistication.
Coffee machines seem to fail from a combination of borderline under supply of peak demand and non signwave.
I know of several £400+ units to die in that environment.
Any generator manufacturer is going to make it very clear they have included that upgrade, to support the appropriate upgrade in cost.
It's highly unlikely an old portable generator is 'pure' signwave but if it is, it would be a surprise to not have it made clear on the labeling/decals.
If there's a specific job for a genny that doesn't req pure, then that's cool. If you want a genny, for just-in-case, the pure signwave makes sense as you can just get on without wondering about the possibility of damage, regardless of whatever usage requirement pops up.
Most modern quality electronics will likely be protected enough to cope via onboard power supply circuitry, but not all.
Any cheap stuff will only have cheap competents, and no protection or sophistication.
Coffee machines seem to fail from a combination of borderline under supply of peak demand and non signwave.
I know of several £400+ units to die in that environment.
harvey38
Well-Known Member
Totally agree, we had 330A on our Freeman 26 based on the Thames.
On our Aquastar Ocean 38, we have 880A of house battery plus 110A for each engine and another 110A for the onboard, water cooled genset.
ianc1200
Well-Known Member
Hi Paul
Hopefully might see you next week & can show you, but essentially i'm stuck with what I've got, at least for the while. These Varta batteries are an odd flat shape to me, I'm used to four 120 amp hour standard size/shaped leisure batteries + starter batteries on my wooden motor cruiser, so having a much larger boat but much smaller battery capacity is odd/wrong, but essentially I'm preparing for Broads & Thames trips so next to adapt what I've got. I think the previous owners cruised from marina to marina so didn't need more capacity.
ianc1200
Well-Known Member
Two of the AQ38's I looked at had gennys in the engine room, but that blocked access via the aft cabin door. 880 amp hours seems right for the size of boat.
ithet
Well-Known Member
So doesn't my old generator's alternator produce a pure sign wave? And then it's traditional transformer also? That I think is the nub of my question as to whether it will power my charger OK.
I thought the "competent electronic circuitry" was needed when a switch mode inverter was part of the unit, as they produce a square wave that needs to be smoothed. This is not the case on my old Genny.
westernman
Well-Known Member
If you have 880 amp hours of lithium battery, you can charge that at one hell of a rate.
I would stuff a 250A alternator (or even two) onto the main engine and use that to re-charge the batteries and power the inverter. That is much more than you will get out of a normal mains charger.
I would avoid having a petrol generator at all costs.
PaulRainbow
Well-Known Member
880Ah of lead acid is a lot on a 38ft boat, it's going to weigh circa 240Kg and cheap leisure batteries would cost close to £1000.
880 Ah of Lithium on the OPs boat would be far more than would be needed and if discharged to a low, but safe, SOC it would take something like 8 hours at 100A to charge them back up. There needs to be a reasonable balance between battery capacity and charging capabilities. 880Ah of lead acid gives a usable 440Ah. A pair of 280Ah Lithium packs would give a usable 450Ah and would only weigh 43Kg, cost for the cells alone would be £520, plus BMS DC-DC charger etc.