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Strettonman

Can anyone recommend an invertor

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I’ve just bought an old boat and about to start stripping it out for a refit. Can anyone recommend a good (performance and value) invertor. I am planning to fit a good bank of batteries so should be good for a high output unit. 

 

Also , where can I get hold of a good guide to narrowbat electrics.  I heard somewhere that earthing has an impact on hull corrosion and I’m keen to understand how the invertor should be wired in relation to engine charging and external 240v supply. 

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5 minutes ago, Strettonman said:

I’ve just bought an old boat and about to start stripping it out for a refit. Can anyone recommend a good (performance and value) invertor. I am planning to fit a good bank of batteries so should be good for a high output unit. 

 

Also , where can I get hold of a good guide to narrowbat electrics.  I heard somewhere that earthing has an impact on hull corrosion and I’m keen to understand how the invertor should be wired in relation to engine charging and external 240v supply. 

Good brands are Victron & Mastervolt

Medium brand would be Sterling

Rubbish stuff is ebay (Chinese) stuff.

 

Only you can determine what size you need but remember that the load on the batteries is 1/10th the 'wattage' of the inverter, so (for example) a loaded 3000w inverter will be drawing 300 amps from the batteries and would take a 600Ah battery bank below the recommended 50% SoC in one hour.

 

Do not be tempted to buy a 'combi' (combined battery charger and inverter, as when one fails you lose both items).

 

£1000 should get you a good inverter.

Edited by Alan de Enfield

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Thanks. 

 

I take it you should not run the batteries down to less than 50% SoC. do invertor have a cutoff to stop over draining you batteries. 

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I have just bought one (3kw) from Sunshine Solar which is set up at home not on the boat. On test it has done well over a 3 hour period. I am planning a longer test soon . Initial impressions are very good.

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Your methodology for putting charge back into your batteries should figure in your calculation of the inverter size and is a crucial and fundamental element of your entire electrical strategy.

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Of course it is not just about having a big battery bank - it is far more about having the generating / charging capacity to adequately put back the hundreds of Amp Hours that having and using a high powered iverter will drain from that bank.

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2 minutes ago, Strettonman said:

Thanks. 

 

I take it you should not run the batteries down to less than 50% SoC. do invertor have a cutoff to stop over draining you batteries. 

I would strongly recommend spending quite some time on this website, using the search feature, as your question suggests that there is a lot of information here that you urgently need to know.

4 minutes ago, DaveR said:

I have just bought one (3kw) from Sunshine Solar which is set up at home not on the boat. On test it has done well over a 3 hour period. I am planning a longer test soon . Initial impressions are very good.

Sine wave quality? Standby power usage? Reliability?  

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Op you could get someone from the forums to come and visit I believe that does happen

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8 minutes ago, Strettonman said:

Thanks. 

 

I take it you should not run the batteries down to less than 50% SoC. do invertor have a cutoff to stop over draining you batteries. 

Yes (sort of) The inverter cut-off tends to be around the 10.5-11.0 volts at which stage you had done irrepairable damage to your batteries.

 

Before spending money :

 

1) you need to do a FULL electrical audit of all your planned electrical items (then add 50% for extra stuff you'll add in in the future)

2) work out how you are going to replace the power used (bear in mind that solar is only much use for - maybe - 7 or 8 months of the year)

3) determine how you are going to monitor your batteries condition.

 

Then go out and buy the cheapest set of batteries that you can get as ANY batteries you buy may only last a couple of weeks, buy a 2nd set and hope you have learned from destroying the 1st set.

After (maybe) 3 months buy a set of 'quality batteries' and with care these should last you 2-3 years.

 

It 'costs' to learn how to use batteries.

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If you plan to use power in the same manner as a house it will only end up with dead batteries.  Things to think about

 

1). The bigger the inverter the better.  This gives spare capacity for running big appliances, but they will discharge batteries very quickly.  As Alan pointed out in post 2 you could be taking 300A from your batteries.  If you had a bank of 3 batteries that is a current of 100A per battery, most batteries are not designed to supply that sort of current for more than seconds and certainly not for tens of minutes, so you need more batteries.

You can greatly help your batteries by only taking a large load with the engine running so that the alternator supplies a significant proportion of the current, but now you may need to buy a bigger alternator.  If you do go that way, every time someone on the boat forgets and runs the hairdrier and microwave at the same time directly from a small battery bank the more battery damage you will get.

 

2). Leave the inverter running 24/7.  Good for instant use, and allows the use of mains fridges etc.  But a cheap inverter will have quite a high power consumption just for powering itself, maybe 25W (a couple of amps), which over a day is getting on for 25Ahr.  A better inverter will be a lot less and if it has a standby/sleep mode even less.  But of course if you plug in phone chargers etc then it will never sleep.

 

3). Power audit/forecast.  As above this is essential to size up the system, but you can also work backwards, by setting a peak power demand (everything, not just the inverter, but considering engine running/engine stopped ) and power consumption over a 24hr period and work out how to achieve it.

 

4). Having done 3 above, work out how many batteries and the lifetime you expect, and then how you will recharge your batteries  Because of the rules of chemistry, charging batteries to 100% takes maybe 10 hours.  Bearing in mind the inverter is a ‘one off’ cost but batteries are consumable.  So if you go for a big inverter with a big battery bank (maybe silly example) of 10 batteries, every time you destroy your batteries it’s going to cost you a grand to replace, considerably more if you go for traction batteries.

 

I don’t mean to be negative and many boaters have big inverters with mains fridges and moderate sized battery bank and with careful management the batteries can last years.

 

 

 

1 hour ago, Strettonman said:

I’ve just bought an old boat and about to start stripping it out for a refit. Can anyone recommend a good (performance and value) invertor. I am planning to fit a good bank of batteries so should be good for a high output unit. 

 

Also , where can I get hold of a good guide to narrowbat electrics.  I heard somewhere that earthing has an impact on hull corrosion and I’m keen to understand how the invertor should be wired in relation to engine charging and external 240v supply. 

A good all round book is the 

The Narrowboat Builder's Book by Graham Booth.

and download a copy of the BSS checklist

Edited by Chewbacka
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That’s some great advice. Thanks very much. 

Do people tend to put in 12v power outputs as well as 240v so you can run phone chargers etc without needing the invertor ? 

 

Also, I was planning to stick with a small caravan fridge that will run off 12v (and gas I think) but are they any good or should I plan for a 240v fridge. As I’m not going to live aboard there will be times when it is just all switched off. 

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3 hours ago, DaveR said:

I have just bought one (3kw) from Sunshine Solar which is set up at home not on the boat. On test it has done well over a 3 hour period. I am planning a longer test soon . Initial impressions are very good.

+1 for that. We have a 1 kW PSW / 2 kW peak which has run well and to spec for several years. Reasonable price and there's always something on special offer.

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We only have 12v sockets. Our inverter is only for power tools. Its off 99% of time.

no mains ring on the boat.  We have had 6 boats only 2 with a mains ring. If you dont need mains dont have it. I cant think of much on a boat that you need mains for. 

 

Popcorn ready

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7 minutes ago, Strettonman said:

That’s some great advice. Thanks very much. 

Do people tend to put in 12v power outputs as well as 240v so you can run phone chargers etc without needing the invertor ? 

 

Also, I was planning to stick with a small caravan fridge that will run off 12v (and gas I think) but are they any good or should I plan for a 240v fridge. As I’m not going to live aboard there will be times when it is just all switched off. 

I don’t have 12v sockets around the boat, but I do have usb charge points by the bed and in the saloon.

As to fridges, I don’t live aboard and have solar panels so can manage an inverter being on for long periods so have a mains fridge.  Mains fridges are a lot cheaper and if A+++ rated tend to be quite frugal with power so long as you don’t open the door too often.  That said, others much prefer 12v fridges.  

Read the bss before fitting a gas fridge, and I’m told a gas/12v fridge is very inefficient when running on batteries.

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6 minutes ago, Strettonman said:

That’s some great advice. Thanks very much. 

Do people tend to put in 12v power outputs as well as 240v so you can run phone chargers etc without needing the invertor ? 

 

Also, I was planning to stick with a small caravan fridge that will run off 12v (and gas I think) but are they any good or should I plan for a 240v fridge. As I’m not going to live aboard there will be times when it is just all switched off. 

 

That type of fridge should NEVER be run from 12V on boats because typically there is no thermostat for the 12V heater (yes heater) and they draw about 8 amps continually. You end up with solid milk and tomatoes. The 12V is intended to be used while you drive your caravan to the site so you keep the contents cool while travelling. While driving the alternator produces the 8 amps so it does not matter.  Although the BSS now allows such fridges on private boats they are not CE marked for boat use and I understand any Gassafe engineer working on the boat will instantly disconnect it and condemn it. (as per letter in a recent Canal Boat magazine).

 

You can get - at a price - 12V compressor fridges that typically consume less than 50Ah [er day and nowadays maybe 30 Ah.

 

For 12V wiring and some domestic plumbing stuff see my website (TB-Training.co.uk)

 

Yes, peopel dof it 12V outlets a swell as 240V AC ones but the type of outlet for the 12V is often hotly contested because the car cigarette lighter sockets types are pretty rubbish.

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16 minutes ago, Strettonman said:

Also, I was planning to stick with a small caravan fridge that will run off 12v (and gas I think) but are they any good or should I plan for a 240v fridge. As I’m not going to live aboard there will be times when it is just all switched off. 

A caravan fridge that runs on both gas and 12 volts will inevitably be of a type called "absorption".  Running an absorption fridge on 12 volts uses probably at least 4 times as much electricity as a 12 volt "compressror" fridge, as it will draw at least 8 amps probably, and are often not thermostatically controlled, so will run continually.

 

You absolutely do not want to be running one of these fridges on 12 volts.

EDIT: Cross posted with Tony, but the message is the same!

Edited by alan_fincher

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It depends on what you plan to do with the inverter. If its critical, like driving a fridge 24 hours a day, then a proper good one from somebody like Victron is the way to go.

If you plan to work it really hard (big hairdriers/washing machines) then again probably get the good one.

For lighter duty occasional use (smaller power tools) then a "selected good" Chinese job should be fine. Get one from Bimble solar rather than eBay, and build in a huge safety margin, if you plan to use 500W then get the 1000w version.  Pure sine are now quite good value so no point in getting modified sine.

 

.............Dave

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If the likes of Victron and Mastervolt are outside of your budget I'd recommend a Sterling PSW inverter. I didn't want to splash out on a Victron or Mastervolt unit but equally I did not want to settle for Chinese rubbish, so I went for a Sterling 1600W Pure Sine Wave Inverter (SIB121600), not bad for £320 that I paid last year. It won't power a microwave or a vacuum cleaner but to be honest I am not sure I'd want to be running either from the batteries anyway.

 

 

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There is a 12v boating group on Facebook which has a lot of useful information on it.

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24 minutes ago, Richard T said:

There is a 12v boating group on Facebook which has a lot of useful information on it.

It doesn’t contain any more expertise than here, plus you have to cope with the dreadful Facebook style of posting where you can’t quote any particular post. But if Facebook is your thing then go for it.  

6 hours ago, Strettonman said:

where can I get hold of a good guide to narrowbat electrics.

In addition to the advice above have a read of this:

https://www.canalworld.net/forums/index.php?/topic/95003-battery-charging-primer/

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You can get a better quality inverter, Victron, or Mastervolt with a lower output for your money, than a poorer quality one of greater output. The big advantage of a higher quality inverter is the greater efficiency. More of your precious battery charge ends up as useful mains, rather than heat. If you have the right type of mains equipment then you don't need an expensive wasteful 3kW inverter. A mains electric fridge needs around a 1000W inverter to start it up, due to the very high inrush current for a fraction of a second as the compressor starts. Automatic washing machines use a lot of power to heat the water. This can be avoided if you have a twin tub, which uses only a few hundred watts and gets hot water by other means. There are tricks with modifying auto washers to do hot water fill. Washers are contentious amongst boaters. You'll get a lot arguing for twin tubs and a lot arguing for autos. Not as bad as the toilet holy war though.

 

Battery vacuum cleaners can be charged at much lower currents than the 1300W needed for most mains ones. Similarly, battery power tools, especially Makita, which use the same batteries for many tools, can be charged at low current. Ultimately, a similar charge may be removed from the batteries and will need replacing, but it is taken out more slowly, so less stress on them. In addition, battery equipment tends to be more efficient and use less electric than mains, as the designers have had to actually think about consumption, rather than just shove in a bigger motor.

I currently have a 1600W Victron inverter/charger on my boat. Doing it again from scratch, I'd have separate charger with a 1000W inverter from Victron, or Mastervolt.

 

Jen

Edited by Jen-in-Wellies

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6 hours ago, roland elsdon said:

We only have 12v sockets. Our inverter is only for power tools. Its off 99% of time.

no mains ring on the boat.  We have had 6 boats only 2 with a mains ring. If you dont need mains dont have it. I cant think of much on a boat that you need mains for. 

 

Popcorn ready

I will have some of your popcorn ? here is my twopenneth. We have no 12 volt sockets on this fab purpose built liveaboard boat. We have in excess of thirty mains sockets running both sides of the cabin. We have a brill inverter switched on 24/7 365 that only draws 0.3 of an amp when resting. We have only mains kit onboard. Having mains kit saves us fifteen billion pounds on costs of inferior 12 volt stuff and gives us humungously more choice of kit. We also have hot and cold water pipes both sides of the cabin full length and central heating running full length both sides of the cabin. We also have a dometic travel power on the engine to do any heavy duty work. Af ter buying a mains boat several years ago I am never going back to 12 volt. The lights are 12 volt and pumps etc. All runs full time when off grid from 4 x 110 a/h batteries with zero problems. This boat was specced by a boatyard owner and built at his yard for his personal use and he sure knew what he was doing.

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2 hours ago, WotEver said:

It doesn’t contain any more expertise than here, plus you have to cope with the dreadful Facebook style of posting where you can’t quote any particular post. But if Facebook is your thing then go for it.  

 

 

Facebook is horrid, its just one long stream of stuff, no topics etc, plus the advertising. But, the bloke who runs the12v group (and it is a mostly a one man show) appears to be very switched on ? and answers questions on a wide range of electrical issues, and in my opinion every answer he has given has been spot on.  This forum has lost a lot of expertise over the last few years. There are a few who know their stuff but many are just repeating what they have read here in a "Chinese whispers" fashion, and most just recommend whatever bit of equipment they happen to own. Do we have anybody here who really grasps electrical theory and has worked on a wide range of boats with a wide range of electrical equipment???

 

.............Dave

 

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9 hours ago, system 4-50 said:

Sine wave quality? Standby power usage? Reliability?  

 

Pure sine wave, 12v input, 220 out. Rest of the information is on the web site/ information with the unit. As I said I have this unit set up at home and is for emergency back up for when we have power failures. The only heating in the house requires 220 volt input so if the lights go out we do get somewhat cold.

 

Hooked up to 4 x 110Ah batteries. As I said further tests to be done. The last 3 hour test saw the batteries drop from 12.8 volts to 12.5 volts.

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37 minutes ago, dmr said:

the bloke who runs the12v group (and it is a mostly a one man show) appears to be very switched on

Yep, Phil is pretty good. I’ve had my disagreements with him though, he’s not perfect. 

39 minutes ago, dmr said:

Do we have anybody here who really grasps electrical theory and has worked on a wide range of boats with a wide range of electrical equipment???

Yes, several. Tony B for one. 

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