suitcase generator vs running the (main) engine?

[dgadee]

Beta say:

"As a guide

No problem to run the engine to warm the calorifier water , as long as it is not continuously every day.
Assume you will use the engine at some time on load each day

1 ) Make sure the oil is 15W/40 mineral or part synthetic
2 ) Turn the engine speed up to 1200 rpm this will charge batteries more quickly less load on the belt if the batteries are low
and also warm the calorifier
3 ) Make sure the engine is serviced correctly ie tube stack etc is clear."

So, I can happily forget about the suitcase generator.

 

[Mistroma]

Beta say:

"As a guide

No problem to run the engine to warm the calorifier water , as long as it is not continuously every day.
Assume you will use the engine at some time on load each day

1 ) Make sure the oil is 15W/40 mineral or part synthetic
2 ) Turn the engine speed up to 1200 rpm this will charge batteries more quickly less load on the belt if the batteries are low
and also warm the calorifier
3 ) Make sure the engine is serviced correctly ie tube stack etc is clear."

So, I can happily forget about the suitcase generator.

Running the engine for a couple of hours each day will get a decent charge back but a lot depends on the other parts of the system. I've already mentioned most of these earlier.

I'm assuming a fairly normal battery setup with lead acid, standard alternator etc. The alternator will supply a decent current for 20-30 minutes and then drop quickly.

Just to guess some figures to make the point as I don't know about your system in much detail.
Starting with batteries at 60%-70% SOC, you might get 30A for the first 30 minutes and then taper quite quickly to 10-15A and continue down to 5-10A after an hour. You need to put a LOT more back in than you take out if you want to get to 100%.

In reality, you will be aiming to get back to 85% each day to give your batteries some chance of a decent lifespan. There's a trade-off between cost of new batteries every few years and cost of enhanced charging to get longer battery life.

Solar is very helpful in this scenario as it can continue to charge for the rest of the day, giving a decent proportion of battery acceptance. You could run the engine for 10 hours or run it for 1 hour plus remainder on solar. The resulting SOC can be the same in either case if you have sufficient solar.

Engine in the morning and then solar works well at anchor. Not so well on passage as the sails will often shade the panels though you will usually run the engine at some point.

My point is that you should not assume that just running the engine is the best option. Consider all the other parts of the system and your budget.

 

[wiggy]

I have a beneteau first 31.7 and we can survive perfectly well with 4 of us on board, basically 4 adults as the kids are 18 and 22, using 200w of solar on the south coast. I don’t have an arch but simply hang the panels on either a guard rail or across the back of the cockpit if sailing or motoring. I have wooden legs to hold the panels at an appropriate angle. We have a VICTRON MPPT controller and 240ah of SLA battery. We have the fridge on 24/7, led lighting and charge all devices as needed. On a sunny day with the panels pointing directly at the sun we are on float by about 10am on a cloudy day it might take until late afternoon. Never mind dodgy data and ‘evidence’ this is real live!

 

[roaringgirl]

I know a couple of people on monohulls who have a few solar panels they can move around on the deck/coachroof to avoid shading.

We live aboard and have 450 solar and a Rutland 1200 windgen. When at anchor we can live indefinitely without ever running the engine, including making enough water for a family of 4 and running a fridge that makes ice. We find when underway that the sails often overshadow some of the panels, so on multi-day passages we use a tow-gen too.

It makes me a bit sad when we are sitting in beautiful anchorages enjoying the serenity, and someone fires up a generator.

 

[Graham376]

It makes me a bit sad when we are sitting in beautiful anchorages enjoying the serenity, and someone fires up a generator.

I think most accept generators during mornings when boats coming and going or when obviously working on boat but some folk seem oblivious to others. We had one mooring neighbour who often started an open frame genny late evening and ran it into the early hours, thankfully not here now.

 

[ctva]

…
The main problem with solar is where to put the panels - there is not a lot of free space. I have considered "solar dodgers" and could revisit that idea.

Boat is a Westerly Storm 33

…No. That is only one thing he said - he also said he does not want to fit a gantry which would be necessary to fit the kind of solar you are advocating…

No one mentioned a gantry, dodgers as shown in one of the earlier posts was suggested and confirmed as above as an option. Stop miss quoting or obtusely interpreting help and suggestions being offered.

 

[dgadee]

Running the engine for a couple of hours each day will get a decent charge back but a lot depends on the other parts of the system. I've already mentioned most of these earlier.

I'm assuming a fairly normal battery setup with lead acid, standard alternator etc. The alternator will supply a decent current for 20-30 minutes and then drop quickly.

Just to guess some figures to make the point as I don't know about your system in much detail.
Starting with batteries at 60%-70% SOC, you might get 30A for the first 30 minutes and then taper quite quickly to 10-15A and continue down to 5-10A after an hour. You need to put a LOT more back in than you take out if you want to get to 100%.

In reality, you will be aiming to get back to 85% each day to give your batteries some chance of a decent lifespan. There's a trade-off between cost of new batteries every few years and cost of enhanced charging to get longer battery life.

Solar is very helpful in this scenario as it can continue to charge for the rest of the day, giving a decent proportion of battery acceptance. You could run the engine for 10 hours or run it for 1 hour plus remainder on solar. The resulting SOC can be the same in either case if you have sufficient solar.

Engine in the morning and then solar works well at anchor. Not so well on passage as the sails will often shade the panels though you will usually run the engine at some point.

My point is that you should not assume that just running the engine is the best option. Consider all the other parts of the system and your budget.

I have 100w of solar on an arch. I think 20 mins of engine will do me. Water is actually more of a problem than power.

 

[Mistroma]

I have 100w of solar on an arch. I think 20 mins of engine will do me. Water is actually more of a problem than power.

Exactly, OP doesn't have solar. I was pointing out that just running the engine for a short while gets water but won't normally get batteries back to a decent SOC. I have 345W plus 100W roaming (for early/late season). Mostly OK for power but sometimes run the engine to get hot water. I usually use solar showers but do end up running the engine 1-2 times each year to get hot water.

You must have fairly low power requirements with 100W. How are you measuring SOC? I use Smartgauge and coulomb counter daily plus temperature corrected SG every 6 weeks.

I'm in Greece and an arch provides useful extra shade as well as somewhere to hang panels. I also have 145W lying flat on the coach roof.

 

[roaringgirl]

I

I think most accept generators during mornings when boats coming and going or when obviously working on boat but some folk seem oblivious to others. We had one mooring neighbour who often started an open frame genny late evening and ran it into the early hours, thankfully not here now.

I guess I accept it, but I don't like it at all.

 

[dgadee]

Exactly, OP doesn't have solar. I was pointing out that just running the engine for a short while gets water but won't normally get batteries back to a decent SOC. I have 345W plus 100W roaming (for early/late season). Mostly OK for power but sometimes run the engine to get hot water. I usually use solar showers but do end up running the engine 1-2 times each year to get hot water.

You must have fairly low power requirements with 100W. How are you measuring SOC? I use Smartgauge and coulomb counter daily plus temperature corrected SG every 6 weeks.

I'm in Greece and an arch provides useful extra shade as well as somewhere to hang panels. I also have 145W lying flat on the coach roof.

2 boats. One Scotland and one Greece. Local has 100w and Greece 245w solar. Local boat used for shorter trips and Greece for weeks without electric connect. Water is more if a hassle than power on both. Both have fridges and not too much else.