Using our emergency genny. Risk to charger!

[pcatterall]

We carry a small cheap ( 600 Watt ?) generator intended mainly for emergencies like foolishly flattening the batteries!
We have never used it in anger though we check it each season.
I know we can safely use the built in battery charger but I recall it is very low out put ( under 5 amps) but worry that if we put the 220volt output
through our 20amp charger it could damage the charger ( I recall warnings about square sine waves or similar and pseudo wave forms but have forgotten the details)
The charger is fairly basic and was sub £100 but it has been good and we don't want to ruin it.
A new better ( quieter) suitcase genny could be an option if it had the 'correct'' waveform' but currently it is there for the odd emergency.
Advise please

 

[Deleted member 36384]

I have a 5kVA generator, simple type, that I used when refurbishing the boat. One day the SterlingPro Charge did not work although it had before with the generator. I would not use the generator again plugged into the boats shore power, although I can't say that it was the generators fault, but the ProCharge Ultra was about 3 years old. I would have thought that you only need a battery charger on the your own generator to get the engine up and running and then use the main charger.

 

[prv]

I recall warnings about square sine waves or similar and pseudo wave forms but have forgotten the details

That applies to inverters, that turn DC into AC. Normally the DC is from batteries, but there are also generators that generate DC and then use a built-in inverter because this means it doesn't matter what speed the engine turns at and they can throttle down when under low load. For an inverter generator, the same waveform considerations would apply.

For a traditional generator, the AC frequency is defined purely mechanically by the speed at which it's spinning, which means it always has to run at a particular engine RPM (which can be unnecessarily noisy when load is low) but should mean that the wave-form is nice and smooth because it's naturally generated rather than an inverter trying to assemble it electronically out of DC.

So for this application you either want a basic mechanical generator or a sophisticated inverter one, but not the middle ground of a basic inverter genny that does a poor job of making smooth waves. Any idea what type yours would be?

Pete

 

[lw395]

Look for a charger with a wide input voltage spec.
If it is spec'd to cope with 100-250 VAC, 50-120Hz, it won't be too fussy about a bit of dirt from the generator.
I have a nice old switch mode power supply, any old crap in, 14.3V out at up to 25A. It is absolutely not a 'smart charger' but it earns its keep.

 

[FulmarJeddo]

As well as sailing we also caravan. There was a time that it was unadvisable to use an older mechanically governed generator with caravan chargers. I did wreck a caravan charger using it with a Honda EX650. Apparently they can produce surges that the charger circuitry can't cope with. We now have a modern caravan and I had it serviced where it is stored away from mains electricity. I also have 2.8 - 3kva manually governed generator. The caravan service engineer assured me that modern chargers are perfectly safe to use on a generator and have improved circuitry that protects against surges. I suspect this is probably the same on boat chargers, but no guarantees. If it is a modern charger it maybe worth contacting the manufacturer to check.

 

[pcatterall]

Thanks all. That's good information. I will check the details of the genny and the charger when next out there ( in Spain).

 

[Lon nan Gruagach]

one way a small genny can upset electronics is if the electronics is the only load...
Start genny, wait till it settles
Switch on electronics.
Genny takes a power hit, speed drops, raises and waggles around a bit, same with the voltage.
Meanwhile your electronics is wondering what on earth it did wrong to deserve such a supply.

Your solution is to first connect a substantial resistive load such as a light bulb, power that, then turn on the electronics.

For a 20A charger, thats gotta be about 300W, so a 100W light bulb (good old filament style) oughta settle the genny. But sure, check waveforms on both to see if its got any chance of flying.

 

[lw395]

one way a small genny can upset electronics is if the electronics is the only load...
Start genny, wait till it settles
Switch on electronics.
Genny takes a power hit, speed drops, raises and waggles around a bit, same with the voltage.
Meanwhile your electronics is wondering what on earth it did wrong to deserve such a supply.

Your solution is to first connect a substantial resistive load such as a light bulb, power that, then turn on the electronics.

For a 20A charger, thats gotta be about 300W, so a 100W light bulb (good old filament style) oughta settle the genny. But sure, check waveforms on both to see if its got any chance of flying.

That is good practice.
A 20A battery charger will only be 300W when it's running at full power. Mostly they fire up and do a bit of 'thinking' for a few seconds before putting any power into the battery. So the charger may be vulnerable to poor regulation in the generator at no-load.
I used to have one of those cheap chinese 600W generators, I used to connect a couple of 50W halogen spots to it. If the bulbs blow, you'll know there's a problem....

 

[srah1953]

"Originally Posted by Lon nan Gruagach
one way a small genny can upset electronics is if the electronics is the only load...
Start genny, wait till it settles
Switch on electronics.
Genny takes a power hit, speed drops, raises and waggles around a bit, same with the voltage.
Meanwhile your electronics is wondering what on earth it did wrong to deserve such a supply."


I would have thought the generator provides ac power to the boat shore power inlet which is going to the charger which is charging the batteries, which are then powering the electronics, etc. Why would the load applied to the batteries matter? Or is the OP referring to a different setup. I'd really like to know because I was intending using a Honda EU 20i for a similar purpose.
Thanks

 

[pcatterall]

"Originally Posted by Lon nan Gruagach
one way a small genny can upset electronics is if the electronics is the only load...
Start genny, wait till it settles
Switch on electronics.
Genny takes a power hit, speed drops, raises and waggles around a bit, same with the voltage.
Meanwhile your electronics is wondering what on earth it did wrong to deserve such a supply."


I would have thought the generator provides ac power to the boat shore power inlet which is going to the charger which is charging the batteries, which are then powering the electronics, etc. Why would the load applied to the batteries matter? Or is the OP referring to a different setup. I'd really like to know because I was intending using a Honda EU 20i for a similar purpose.
Thanks

Yes the plan was to use the AC inlet to put power into the mains supply to which the battery charger is connected. I guess that the 20i means it is an inverter unit?

 

[GHA]

I would have thought the generator provides ac power to the boat shore power inlet which is going to the charger which is charging the batteries, which are then powering the electronics, etc. Why would the load applied to the batteries matter? Or is the OP referring to a different setup. I'd really like to know because I was intending using a Honda EU 20i for a similar purpose.
Thanks

I've used a honda EU10 for years powering a 20A pro charge ultra with no probs at all. Just careful the exhaust is no where near the companionway or your CO alarm will go off. Everything else is powered from the batteries so can't tell the difference.

 

[srah1953]

I've used a honda EU10 for years powering a 20A pro charge ultra with no probs at all. Just careful the exhaust is no where near the companionway or your CO alarm will go off. Everything else is powered from the batteries so can't tell the difference.

Ta

 

[Lon nan Gruagach]

I would have thought the generator provides ac power to the boat shore power inlet which is going to the charger which is charging the batteries, which are then powering the electronics, etc. Why would the load applied to the batteries matter? Or is the OP referring to a different setup. I'd really like to know because I was intending using a Honda EU 20i for a similar purpose.
Thanks

By "electronics" I was referring to the charger itself, not what it was providing power for.
I was talking about the general case of running non-resistive loads ,particularly thosw with switch mode power supplies (transformerless), from a generator.

Soz for the confusion.