Charging House Batteries From a Honda Portable Gen

[PaulRainbow]

Paul, like others here I've always been in the practice of feeding my Honda genny's output into my boat's shore power inlet. Why do you consider that to be an unsafe procedure? This is not a critisism of your opinion but a desire on my part to avoid doing something stupid through ignorance.
Mike

It isn't me that considers it to be unsafe, it plainly is unsafe. Sure, it will work, it'll power stuff that you plug in, but what you don't get is any safety if things go wrong. It would be in breach of current build regs for new boats, it would be in breach of regs if it was carried out ashore in a domestic or industrial property.

The correct procedure when installing an AC power system on a boat is to connect the incoming supply to a RCD, RCBO, MCBs etc, as applicable. These devices protect people from electrocution and protect the onboard systems from overload. The neutral and Earth must be bonded together at the power source and everything must be Earthed. In the case of shore power, the bonding is done shore side, as is the Earth. Current regulations also require that the Earth be made onboard too, to the water, in which case a galvanic isolator or isolation transformer should be fitted. Older boats may not have the Earth connected to the water and should get away without the GI or IT.

When one is fitting an inverter or a generator, both are subject to those same rules. There are no specific rules governing installations on boats that are not new, but it makes sense to do so. So, the neutral and Earth must be bonded and everything must be |earthed to the water (and shore power, naturally, when plugged in. In this case, a GI or IT should be fitted if the shore power was previously not connected and/or one was not fitted.

If an inverter or generator cannot be connected following these simple, but essential for safety, rules, it should not be fitted as a "fixed installation". Having a small portable generator or inverter onboard as a stand alone device, just plugging something into its own power sockets might be acceptable, but the manufacturers instructions for Earthing should still be followed.

If the rules are not followed RCDs may not operate, faults are not Earthed and someone could get electrocuted. Whether or not we read of people being electrocuted is immaterial, the danger is still there.

 

[wingcommander]

My apologies , note to self ......read from post no 1 in future. Fully agree with you Paul.

 

[PaulRainbow]

This is a typical inverter/generator thread on PBO.

Some of the posts here are very disappointing.

Who wants to phone their son/daughter and tell them their child has just been electrocuted ?

We spend significant sums of money on safety equipment, some of which requires regular maintenance/replacement, why would we not connect an Earth wire that costs pence and fit an inexpensive GI ?

 

[KeelsonGraham]

Question: why would you use a portable genset to charge house batteries rather than run the engine and have the alternator charge your batteries?
Would a genset charge your batteries faster then the engine or are they more economical?
Just wondering.

I need the gen set to power the water maker so, while it’s running, I thought why not top up the batteries.

 

[KeelsonGraham]

It isn't me that considers it to be unsafe, it plainly is unsafe. Sure, it will work, it'll power stuff that you plug in, but what you don't get is any safety if things go wrong. It would be in breach of current build regs for new boats, it would be in breach of regs if it was carried out ashore in a domestic or industrial property.

The correct procedure when installing an AC power system on a boat is to connect the incoming supply to a RCD, RCBO, MCBs etc, as applicable. These devices protect people from electrocution and protect the onboard systems from overload. The neutral and Earth must be bonded together at the power source and everything must be Earthed. In the case of shore power, the bonding is done shore side, as is the Earth. Current regulations also require that the Earth be made onboard too, to the water, in which case a galvanic isolator or isolation transformer should be fitted. Older boats may not have the Earth connected to the water and should get away without the GI or IT.

When one is fitting an inverter or a generator, both are subject to those same rules. There are no specific rules governing installations on boats that are not new, but it makes sense to do so. So, the neutral and Earth must be bonded and everything must be |earthed to the water (and shore power, naturally, when plugged in. In this case, a GI or IT should be fitted if the shore power was previously not connected and/or one was not fitted.

If an inverter or generator cannot be connected following these simple, but essential for safety, rules, it should not be fitted as a "fixed installation". Having a small portable generator or inverter onboard as a stand alone device, just plugging something into its own power sockets might be acceptable, but the manufacturers instructions for Earthing should still be followed.

If the rules are not followed RCDs may not operate, faults are not Earthed and someone could get electrocuted. Whether or not we read of people being electrocuted is immaterial, the danger is still there.

So, are you saying, run a new wire from the existing AC RCD to something that earths to the water. Or does a portable AC gen require an entirely different setup?

 

[Graham376]

Paul,

I don't doubt what you say is correct as far as regs are concerned but - you mention it's OK to use an extension lead from the generator and plug the charger into that - correct?

In my case, the on-board mains circuit is isolated except for the earth to anode so is in effect no different to an extension lead with a multi socket. It's fed by the shore power socket via rcd and fused consumer unit. We're mooring based, powered by solar so no galvanic isolator fitted as connecting to shore power is a very rare event, mainly when in boat yard for a months annual maintenance. Although you obviously disagree, I really see little if any danger in practice.

Graham.

 

[Travelling Westerly]

In my case, the on-board mains circuit is isolated except for the earth to anode

Sorry if I'm incorrect but surely this statement means your on board AC system is not isolated

 

[dunedin]

If seeking to charge on long passages, wouldn’t a Watt&Sea or similar be better (and safer and quieter and greener)?

 

[Graham376]

Sorry if I'm incorrect but surely this statement means your on board AC system is not isolated

Yes, I see what you mean, the connection to the anode should allow the rcd to work. The circuit around the boat is isolated in that nothing is connected to it unless I physically plug something in so, it's no different to having an extension lead.

 

[Koeketiene]

OP said "help charge the house batteries on long passages "

I'd rather run the engine, in gear, motor sailing, for an hour than have a genny running on deck. Batteries get charged faster (usually), a bit more boat speed and usually a free tank of hot water.

That would have been my thinking too.
I have a very minimalist boat with power requirements to match.
My fridge is the only really powerhungry item.
With 130W of solars, on a reasonably clear day, I can get by with motorsailing 1 or max 2 hours/day.
Engine needs 2.3ltr/hr.

Just saw the post that OP already has a genset to run a watermaker, so maybe it makes sense in his case.

 

[PaulRainbow]

Yes, I see what you mean, the connection to the anode should allow the rcd to work. The circuit around the boat is isolated in that nothing is connected to it unless I physically plug something in so, it's no different to having an extension lead.

Vastly different to an extension lead. I did not suggest using an extension lead to connect to a whole shore power system. I suggested only plugging the battery charger into the generator, that's a single appliance on a totally separate system.

What you have is most likely a centre tapped generator, which has no bonding between the neutral and Earth, a prerequisite in a fixed installation (by connecting a "portable" generator to the boat systems you create a fixed installation and that must, at the very least, comply with the two basic rules that the neutral and Earth must be bonded and the Earth circuit must be connected to the water.

You think that the Earth connection to the anode will enable the RCD to work correctly, this is, sadly, a common misconception. If you have a fault that allows the live wiring in an appliance to come into contact with that appliances metal case (which is Earthed to your anode) there is no circuit, so no current flows and the RCD will not trip. This is why the neutral and earth must be bonded, current can now flow to neutral via the bonding and the RCD trips.

Having just the Earth connected to water poses another danger to life. It is possible for a very small current to "leak" into the water, less than the 30ma required to trip an RCD. This current can paralyse a swimmer in the water, causing what is termed as "electric shock drowning".

Another potential issue is, your generator doesn't actually have a live and neutral, it has two 110V lives. So, if you suffer a problem that blows a fuse, or trips an RCD, the circuit that would usually be neutral is still live.

That's why, if you cannot bond neutral and Earth and you should not make an inverter or a generator part of a fixed installation

Edit: Not all generators are the same and not all can have the neutral and Earth bonded, don't mess around with bonding unless you absolutely know what you are doing. Remember, the AC electricity produced by generators and inverters will kill you just the same as that from a shore based power station.

 

[Koeketiene]

If seeking to charge on long passages, wouldn’t a Watt&Sea or similar be better (and safer and quieter and greener)?

In an ideal world, yes.
But this things are 'not cheap'.
Was quoted 3.6K for a Cruising 300.

 

[PaulRainbow]

That would have been my thinking too.
I have a very minimalist boat with power requirements to match.
My fridge is the only really powerhungry item.
With 130W of solars, on a reasonably clear day, I can get by with motorsailing 1 or max 2 hours/day.
Engine needs 2.3ltr/hr.

Just saw the post that OP already has a genset to run a watermaker, so maybe it makes sense in his case.

Yes, that bit of additional information can make a difference.

It might be worth the OP fitting some solar to keep on top of the batteries and only use the generator for the watermaker.

 

[Momac]

Would something like this not be better ?
Rutland 914i Windcharger 12V - Sunshine Solar - Sunshine Solar Limited

 

[KeelsonGraham]

Yes, that bit of additional information can make a difference.

It might be worth the OP fitting some solar to keep on top of the batteries and only use the generator for the watermaker.

Running an electric autopilot 24/7 on passage takes a lot more Ah than solar can provide.

As far as I can tell from the graphs, the windcharger isn’t great. Only a narrow band of windspeeds in which useful amounts of current are produced.

A Watt and Sea would be great if I could afford £3.6k. A hydrovane would solve a lot of problems if I could afford £5.6k. (Equipping for long passages is already costing me north of £24k).

So my plan is to recharge using a combination of engine and solar. But, while the gen set is on for making water why not top up the batteries as well. Hence my question.

It seems like that isn’t a good idea, but then again no AC circuit or appliance is being used. At sea it’s 12v DC only - apart from whatever AC is supplying the battery charger.

 

[Graham376]

Running an electric autopilot 24/7 on passage takes a lot more Ah than solar can provide.

As far as I can tell from the graphs, the windcharger isn’t great. Only a narrow band of windspeeds in which useful amounts of current are produced.

That depends on how much solar you have and how well balanced sail plan is to reduce autopilot use. We never ran out of battery power on 3 - 4 day passages and had smaller battery bank and solar then.

We no longer have the Aerogen and nothing would tempt me to buy another, solar is far cheaper and from our experience more reliable output even on overcast days.

 

[Momac]

Has the OP considered how much petrol would be required to be carried on the boat for an extended journey and what risks that my involve?

 

[KeelsonGraham]

Yes, he ha

Has the OP considered how much petrol would be required to be carried on the boat for an extended journey and what risks that my involve?

Yes he has! 15 litres for a passage from Las Palmas to St Lucia, either stored in the anchor locker or on the sugar scoop transom.

 

[KeelsonGraham]

That depends on how much solar you have and how well balanced sail plan is to reduce autopilot use. We never ran out of battery power on 3 - 4 day passages and had smaller battery bank and solar then.…….solar is far cheaper and from our experience more reliable output even on overcast days.

Taking the figures from Martin of Jambo (see the ‘How is this possible?’ thread) the daily requirement is about 420Ah. My own rough calculations come out very close to this figure assuming you want to run a fridge, chartplotter and AIS all day and radar at night.

750kw of panels operating a latitude of 30N with the boat pointing E/W are going to give you about 180 Ah. The deficit needs to be made up by running the engine. And maybe a little more from the genset whilst it’s powering the watermaker

 

[PaulRainbow]

Running an electric autopilot 24/7 on passage takes a lot more Ah than solar can provide.

As already said, it depends how much solar you have, how much do you have ?

As far as I can tell from the graphs, the windcharger isn’t great. Only a narrow band of windspeeds in which useful amounts of current are produced.

Agreed, wind is a waste of time these days, IMO.

A Watt and Sea would be great if I could afford £3.6k. A hydrovane would solve a lot of problems if I could afford £5.6k. (Equipping for long passages is already costing me north of £24k).

Yep, doesn't seem terribly cost effective.

So my plan is to recharge using a combination of engine and solar. But, while the gen set is on for making water why not top up the batteries as well. Hence my question.

It seems like that isn’t a good idea, but then again no AC circuit or appliance is being used. At sea it’s 12v DC only - apart from whatever AC is supplying the battery charger.

I can only make people aware of how things should be done and the risks involved if things are not done correctly. I have nothing to gain or lose, whatever anyone decides, but i'd hate to read of someone (or someones crew/loved ones) getting hurt or killed as a result of a poor installation. I'm also not trying to scare monger, but i don't accept the "i've been doing it for years" argument as being a valid excuse for not doing it right.

Some generators can have the Earth and neutral bond made and they can certainly all be Earthed, so it's well worthwhile checking to see if your particular generator can be bonded. If it can, it costs very little to have a proper, safe, installation.