Solar vs Generator

[Robbo]

duplicate post

Edited August 3, 2018 by Robbo

[Alan de Enfield]

8 hours ago, leeco said:

.........….but my inverter plugged into power puts a constant 90amps in

I think you may have a perception problem.

 

Inverters do NOT 'put anything in', an inverter 'tales out' from a battery and if it is indeed drawing out 90 amps than you will pretty soon have problems.

 

Are you sure that when 'plugged in' its not a battery charger 'putting in' 90 amps (for a few minutes)

Edited August 3, 2018 by Alan de Enfield

[Robbo]

 

46 minutes ago, Nick D said:

We spend 3/4 weeks out of the marina at a time so I'm trying to weigh up whether it's worth the investment in solar or a generator.

If you have shore power and charge your batteries at the marina then no you don’t really need either with your cruising habits.    Even a battery monitor is not really needed, although handy and can highlight any issues (if you learn how to read one)

Edited August 3, 2018 by Robbo
Duplicate post

[Stewart Kirby]

Your boat is just over two years old but you needed new batteries. Now not all batteries are created equal but I would expect the batteries to have lasted longer given that you have the boat on shore power and use a battery charger. 

Now, not all engineers are created equal so it’s possibke the one you used did not have the right knowledge and experience to do anything other than a simple test which is inconclusive.

You should not need solar or a generator if everything is functioning correctly. As a first step I would get a Smartguage and start monitoring your setup. If you are not technically minded it’s worth getting it installed by someone who knows what they are doing.

My money is still on a faulty or incorrectly installed alternator, or one that isn’t up to the job.

[leeco]

2 hours ago, Alan de Enfield said:

I think you may have a perception problem.

 

Inverters do NOT 'put anything in', an inverter 'tales out' from a battery and if it is indeed drawing out 90 amps than you will pretty soon have problems.

 

Are you sure that when 'plugged in' its not a battery charger 'putting in' 90 amps (for a few minutes)

It’s a inverter charger.

 

a sterling combi and a quality bit of kit that charges your batteries fast. Like I said I never really use shore power as I’ve always had solar and never used the boat at winter time but will be this year.

[Alan de Enfield]

Just now, leeco said:

It’s a inverter charger.

 

a sterling combi and a quality bit of kit that charges your batteries fast. Like I said I never really use shore power as I’ve always had solar and never used the boat at winter time but will be this year.

So I was correct - it is the charger 'putting in' and not (as suggested) the inverter.

 

It is important to try and be as accurate as possible - newbies reading this site may be tempted to use the Inverter to charge their batteries if they think they will get 90 amps going in (it has been known, and then they wonder why the batteries go flat when they are being charged)

[leeco]

1 minute ago, Alan de Enfield said:

So I was correct - it is the charger 'putting in' and not (as suggested) the inverter.

 

It is important to try and be as accurate as possible - newbies reading this site may be tempted to use the Inverter to charge their batteries if they think they will get 90 amps going in (it has been known, and then they wonder why the batteries go flat when they are being charged)

Good point ?

[Nick D]

1 hour ago, Stewart Kirby said:

Your boat is just over two years old but you needed new batteries. Now not all batteries are created equal but I would expect the batteries to have lasted longer given that you have the boat on shore power and use a battery charger. 

Now, not all engineers are created equal so it’s possibke the one you used did not have the right knowledge and experience to do anything other than a simple test which is inconclusive.

You should not need solar or a generator if everything is functioning correctly. As a first step I would get a Smartguage and start monitoring your setup. If you are not technically minded it’s worth getting it installed by someone who knows what they are doing.

My money is still on a faulty or incorrectly installed alternator, or one that isn’t up to the job.

Thanks for the advice. To clarify, we have only just put the boat in a marina so have not been on shoreline for long. Previously we were treating the batteries as we would have done on a hire boat I. E with not much care or knowledge as to how they functioned. As a result we were draining them down almost completely prior to recharging. Yes, I know this sounds ridiculous but unfortunately you don’t know what you don’t know and now I am better informed and won’t do this again after a costly replacement of the batteries.

 

I now want to care for them in the best way, hence my original question. Hopefully being on a shoreline for the majority of time with a charger and then 3/4 weeks cruising every so often the situation will improve but I do need more accurate information by way of a meter/ gauge. Is Smartgauge a brand or a generic term? Is there a particular one that is best?

thanks again 

[Tony Brooks]

3 hours ago, Nick D said:

I apologise for not being technically minded, so that is why I ask questions on here from people who are!  I paid a supposedly qualified engineer to replace my batteries and test the alternator.  When he said it was ok, I believed him as most non technical people would. I didn't know them about taking various rested readings - I do now, so thank you.

 

Rather  than go through the procedure you describe to see if there is indeed a problem, I was trying to establish earlier whether 'on average' 4 hours cruising was 'generally' enough to charge the batteries. It seems that opinion differs so I may well have to go down that route. Can you tell me what equipment I need to test the rested voltage and what details you need for a power audit?  I am not currently on the boat but hope to be in a few weeks.

 

Yes, I do have a battery charger and twin alternators.  The boat is just over two years old and appears (from a non technical person) to have generally good equipment levels.

The point I was trying to emphasise is that you can ask questions as much as you like and to you they may seem reasonable and simple questions but if a bunch of members start asking for more information to try to help them answer saying what you said or just ignoring then,as others have done, can never get you the  best answer.

 

On the basis the boat is just two years old then on balance the alternator is probably OK but that is not certain. If it is OK and based on my own boat the four hours charging from the engine at cruising revs (not tick over) should get your batteries well but not fully charged. On my boat with a 60 amp alternator and before I put any solar on it and no shore power the batteries lasted around three years before the loss of capacity from long term under charging meant renewal. You seem to also use shore power when in the marina so at the end of each trip your batteries should soon be fully charged again so may last longer. Since fitting 60 watts of solar my batteries now last in excess of  four years (the present set are six years old and seem OK). Now, there must be a reason that you are thinking about solar v generator but I have not picked up on it. I suspect it may be battery problems but why that may be the case is not clear, old age, insufficient charging, run out of cyclic life (possibly related to insufficient charging), or excess use of electricity for your charging regime.

 

Now, with 160 watts of solar I still need to run my engine for a couple of hours every day to get the batteries more or less fully charged and that solar will recharge the battery bank when we  are away from the boat for a few weeks in the winter. However my electricity and boat use and your electricity use and boat is unlikely to be the same so to this is why we need your power audit and charging calculations.

 

On the face of it I agree with those who say that you do not need either solar or a generator as you have shoreline charging in the marina but you obviously think you do so if you cruise in the winter when the solar input is very low then solar will not suffice. This is why I say the only answer is a generator so whatever time of year it is you can charge your batteries when you need to. If you were willing to get involved with battery monitoring etc. then I suspect modest amounts of solar will allow you to stay in one place without running the engine for a day or so but it still comes back to your electricity use, charging regime, and battery bank size..

Edited August 3, 2018 by Tony Brooks

[Tony Brooks]

2 minutes ago, Nick D said:

Thanks for the advice. To clarify, we have only just put the boat in a marina so have not been on shoreline for long. Previously we were treating the batteries as we would have done on a hire boat I. E with not much care or knowledge as to how they functioned. As a result we were draining them down almost completely prior to recharging. Yes, I know this sounds ridiculous but unfortunately you don’t know what you don’t know and now I am better informed and won’t do this again after a costly replacement of the batteries.

 

I now want to care for them in the best way, hence my original question. Hopefully being on a shoreline for the majority of time with a charger and then 3/4 weeks cruising every so often the situation will improve but I do need more accurate information by way of a meter/ gauge. Is Smartgauge a brand or a generic term? Is there a particular one that is best?

thanks again 

The Smarguage is a sort of battery fuel gauge BUT it will reliably tell you when you should stop using electricity and start charging ASAP but is not so good at telling you when to stop charging so in addition you need an ammeter. However to maximise battery life you need to recharge as close to fully each day. Solar is excellent at that in summer as others have described.

 

there are also battery monitors made by at least two companies that give you volts and amps but regrettably more. Regrettably because the percentage charged or time to go before charging all too often turns out to be a lie and as the months go on the lies get larger and larger. If you promises to ignore those problem readings ans stick to amps and volts then one of these like a BVM is all you need BUT you will have to  do a bit of learning so you can infer state of charge from battery voltage but that's for another day. That then brings us back to the non-technical statement, to properly monitor your batteries and deal with electrics in general you need to develop technical skills. A Smartguage for "stop discharging" and an ammeter for "stop charging" is about as non-technical as you can get. I would suggest that you fit and learn to use battery monitoring equipment before anything else.

 

There is a whole new set of problems related to both battery chargers and solar controllers dropping down to what is known as float voltage too soon but if you leave the batteries on shore line charging for weeks then that problem is unlikely to be a major one.

[Robbo]

50 minutes ago, Nick D said:

Thanks for the advice. To clarify, we have only just put the boat in a marina so have not been on shoreline for long. Previously we were treating the batteries as we would have done on a hire boat I. E with not much care or knowledge as to how they functioned.

I wouldn't even bother looking at either solar and especially not a generator.   Just use the boat as you are.    A battery monitor or clamp meter, is handy to see if your current system is performing as it should, but simply looking at the voltage meter in the morning before starting the engine and setting will give you a rough idea how much you are using the batteries.   Basically if it's above 12.1v when your off-grid when you check in the morning before starting the engine to do your cruising, your doing fine.   

 

Note a analogue voltage meter is not really the best to read, digital is really a must here.

Edited August 3, 2018 by Robbo

[Alan de Enfield]

You have 4 x 110Ah batteries they have lasted 2 years.

 

A decent Honda 2kw generator will cost approaching £1000 + running costs.

A decent sized Solar set-up will cost similar.

4x 110Ah batteries cost around £240. (you get £10 each back from them from the scrap man) net price £200

 

For the same amount of money you can get 8 - 10 years worth of batteries and no need to do anything you don't do now, & no need to buy additional monitoring equipment (£100s)

If you do take a little more care out of your batteries (left on charge on a landline) you may well get 4 years out of a set thus achieving 16-20 years for the £1000

 

Your money, your choice.

 

 

[peterboat]

Solar simple I did it years ago and have never looked back. It looks after the batteries while you are away and fully charges them when out cruising. Yes I have LifePo4 batteries which can handle massive charging amps far in excess of what my solar can give, and my alternator is disconnected so that solar is my only method of charging, yet every day my batteries are charged ! its a miracle or the 1kw of solar on the roof that does it. For winter I have a whispergen but this is only run infrequently to make up for the missing sun, so if I was you I would fit solar and see how it goes

[TheBiscuits]

6 minutes ago, peterboat said:

Solar simple I did it years ago and have never looked back. It looks after the batteries while you are away and fully charges them when out cruising. Yes I have LifePo4 batteries which can handle massive charging amps far in excess of what my solar can give, and my alternator is disconnected so that solar is my only method of charging, yet every day my batteries are charged ! its a miracle or the 1kw of solar on the roof that does it. For winter I have a whispergen but this is only run infrequently to make up for the missing sun, so if I was you I would fit solar and see how it goes

Normally I agree with you Peter, but in this case the OP has a mooring with hookup and only cruises for 3 weeks or so.  For anyone without shore power or who spends longer on the boat your advice is bob on.

 

I'd say they should just run the engine while they go to the pub - a couple of quid of diesel per day for 3 weeks against the price of a decent solar setup.

[Robbo]

15 minutes ago, peterboat said:

Solar simple I did it years ago and have never looked back. It looks after the batteries while you are away and fully charges them when out cruising. Yes I have LifePo4 batteries which can handle massive charging amps far in excess of what my solar can give, and my alternator is disconnected so that solar is my only method of charging, yet every day my batteries are charged ! its a miracle or the 1kw of solar on the roof that does it. For winter I have a whispergen but this is only run infrequently to make up for the missing sun, so if I was you I would fit solar and see how it goes

Out of interest how much on average Ah’s/day does you solar get in winter and do you position your solar or is it flat?   Looking at around 880watt myself.

[peterboat]

32 minutes ago, Robbo said:

Out of interest how much on average Ah’s/day does you solar get in winter and do you position your solar or is it flat?   Looking at around 880watt myself.

Its flat but by the end of this year it will be treble the size and tilting!! I am removing the barrus shire and replacing it with an electric motor which is why I have disconnected the alternator to see if I could manage with just solar whilst out cruising. Winter time it meets most of my needs but for the washer or dish washer I fire up the whispergen to make up the missing amps. I dont take any notice of the amps in I just look at the voltage at the end of the day and if they are reading 13.2 or above all is well with the world, summertime they are normally at 13.5 or above, they really are so much better than the full tractions they replaced

[Robbo]

1 minute ago, peterboat said:

Its flat but by the end of this year it will be treble the size and tilting!! I am removing the barrus shire and replacing it with an electric motor which is why I have disconnected the alternator to see if I could manage with just solar whilst out cruising. Winter time it meets most of my needs but for the washer or dish washer I fire up the whispergen to make up the missing amps. I dont take any notice of the amps in I just look at the voltage at the end of the day and if they are reading 13.2 or above all is well with the world, summertime they are normally at 13.5 or above, they really are so much better than the full tractions they replaced

You don’t have to sell me on the LifePo4’s.     Was just wondering what I could expect from a solar bank of your size during the dark months. 

[leeco]

4 minutes ago, Robbo said:

You don’t have to sell me on the LifePo4’s.     Was just wondering what I could expect from a solar bank of your size during the dark months. 

What’s a LifePo4? ?

[Robbo]

1 minute ago, leeco said:

What’s a LifePo4? ?

Sorry, meant LiFePO₄

[leeco]

Just now, Robbo said:

Sorry, meant LiFePO₄

Yeah but what is it a new type of battery?

[rusty69]

6 minutes ago, leeco said:

What’s a LifePo4? ?

lifepofour solar = miserable

[Robbo]

17 minutes ago, leeco said:

Yeah but what is it a new type of battery?

Well it's new compared to LA (Lead Acid), but it's not new new.

 

Basically if your off-grid in winter it's probably the best battery technology to use.   Installation and price is probably the down sides of them.

 

Up sides..

Very high cycle count (around 5000).

Can take a large charging current upto around 99% SoC.

You don't need to fully charge.

No need for the absorption stage like on LA, so charging times are reduced.

Can use majority of the battery capacity and still have very high cycle count.

Voltage stays roughly constant with the SoC unlike LA's.

Overall costs (they can work out cheaper in the long term).

 

Down sides.

They don't like to be sat at 100% SoC for long periods. (so bad if on shore power).

Installation and additional equipment needed.  Not really a drop in replacement for LA batteries even tho some claim to be.

Can't charge at low temperatures at around zero degrees C.

Initial Cost.

Edited August 3, 2018 by Robbo
Added up and down sides..

[peterboat]

15 minutes ago, Robbo said:

You don’t have to sell me on the LifePo4’s.     Was just wondering what I could expect from a solar bank of your size during the dark months. 

I dont know is the simple answer because it works apart from the washer and diswasher, and even on sunny winter days their might be enough to run them. I have all the normal stuff on a boat tv etc I just dont get that bothered by whats coming in I just look at the voltage at the end of the night and as long as its 13.2 or above all is well in my world sorry but it really is that simple with my new battery bank

6 minutes ago, Robbo said:

Well it's new compared to LA (Lead Acid), but it's not new new.

 

Basically if your off-grid in winter it's probably the best battery technology to use.   Installation and price is probably the down sides of them.

They wernt expensive £320 each I have 14,   4 for domestic and 10 for drive on the electric motor

[cereal tiller]

18 minutes ago, leeco said:

Yeah but what is it a new type of battery?

Used as a Sea-Toilet by the RNLI?

[Dr Bob]

1 hour ago, TheBiscuits said:

 

I'd say they should just run the engine while they go to the pub

....bit antisocial dont you think??