Jump to content

12V or 230V?


evilrobotshane

Featured Posts

Hello folks,

 

My new home was previously a floating apartment on permanent shore power, so it has a nice inverter and a decent number of 230V sockets, and basically just lights and pumps on 12V. For continuous cruising, I’d been planning to install a load of 12V sockets and get a 12V television and maybe switch to a 12V fridge, but I’m wondering if that’s worth the medium amount of effort it’d take, or if using the alternator day-to-day isn’t much less efficient, as long as I verify I’m not going to be overloading it. 
 

2100W inverter

540 amps of leisure batteries 

I’m going to stick about 400W of solar up top

 

Thanks!

Link to comment
Share on other sites

Why not go with what you have got and see how you get on? I wouldn't underestimate the effort required to add 12V sockets and cabling unless you already have a large conduit to run them.

 

Definitely add the solar though.

Oh, and some battery monitoring hardware too!

Link to comment
Share on other sites

What make and model of inverter is it? Some have a very high "quiescent" current draw, e.g. my Sterling draws 4A when on but supplying nothing. This is at least irritating, and a complete waste of power. AIUI The better ones draw something less than an amp.

Link to comment
Share on other sites

Sterling as well! Pro Combi S 2100W continuous, 6000W peak. It has a function whereby it’s supposed to go on standby when there isn’t demand on it, but that hasn’t impressed yet (maybe electric toothbrush charger is beneath its dignity, and the fridge might have already been cold). Further experiments I reckon. 

Link to comment
Share on other sites

A better inverter, with a low draw will be cheaper than new 12V electrical gadgets. This gets discussed on here a lot, so do a search and read other topics on this subject. 12V televisions, fridges etc tend to be expensive and poor in features compared with their mains counterparts. A consequence of their very small market and limited number of manufacturers. You'll also have the expense and hassle of wiring the boat with 12V sockets. Don't ignore the cost of that, especially for a 12V fridge, which needs very heavy gauge and thus expensive wires to prevent voltage drop that will stop it working when batteries are less than full.

Take a look at Victron and Mastervolt for inverters. Expensive compared with Sterling and very expensive compared with no-name Chinese Ebay inverters, but you definitely get what you pay for in terms of reliability, not catching fire and not wasting precious battery charge.

 

Jen

Link to comment
Share on other sites

My Mastervolt MICC shows that when my Mastervolt 2000/100 combi is in powersave mode the draw on my batteries is 1.7 a. When you look about the boat and see all the various indicator lights  gauges and devices on standby it's hardly surprising. Remember, there's no such thing as a free lunch and whilst some can be turned off not all can.

Link to comment
Share on other sites

1 hour ago, Jen-in-Wellies said:

 

Take a look at Victron and Mastervolt for inverters. Expensive compared with Sterling and very expensive compared with no-name Chinese Ebay inverters, but you definitely get what you pay for in terms of reliability, not catching fire and not wasting precious battery charge.

Sunshine Solar inverters also get recommended on here.

https://www.sunshinesolar.co.uk/Category/PureSineWave12V

Link to comment
Share on other sites

3 hours ago, evilrobotshane said:

Hello folks,

 

My new home was previously a floating apartment on permanent shore power, so it has a nice inverter and a decent number of 230V sockets, and basically just lights and pumps on 12V. For continuous cruising, I’d been planning to install a load of 12V sockets and get a 12V television and maybe switch to a 12V fridge, but I’m wondering if that’s worth the medium amount of effort it’d take, or if using the alternator day-to-day isn’t much less efficient, as long as I verify I’m not going to be overloading it. 
 

2100W inverter

540 amps of leisure batteries 

I’m going to stick about 400W of solar up top

 

Thanks!

 

I fear you may be looking at this from the wrong end.  The first thing anyone who is going to CC should look into is what it will take to recharge you batteries sufficiently each day or every very few days  to minimise battery deterioration. Although running 12V stuff may reduce the load to some degree and make it a little easier I suepect that with a decent inverter and energy efficient 240 V equipment the difference will not be that great.

 

I agree with Rusty that you definitely need battery monitoring equipment and the learning how to interpret it and which readings may not be the truth.

 

 

Link to comment
Share on other sites

6 hours ago, Tony Brooks said:

i fear you may be looking at this from the wrong end.  The first thing anyone who is going to CC should look into is what it will take to recharge you batteries sufficiently each day or every very few days...

^^^^ this. 
 

Step 1: Do a power audit

Step 2: Work out how you will replace that. 
 

Go back and forth between those two steps until it balances. 


12V vs 230V is pretty much an irrelevance in these calculations. 

Link to comment
Share on other sites

22 hours ago, evilrobotshane said:

Hello folks,

 

My new home was previously a floating apartment on permanent shore power, so it has a nice inverter and a decent number of 230V sockets, and basically just lights and pumps on 12V. For continuous cruising, I’d been planning to install a load of 12V sockets and get a 12V television and maybe switch to a 12V fridge, but I’m wondering if that’s worth the medium amount of effort it’d take, or if using the alternator day-to-day isn’t much less efficient, as long as I verify I’m not going to be overloading it. 
 

2100W inverter

540 amps of leisure batteries 

I’m going to stick about 400W of solar up top

 

Thanks!

 

8 hours ago, evilrobotshane said:

That’s great info, thank you all very much! There’s a great deal currently on one of the Sunshine inverters at about the right power level for me, too. This has saved me a lot of hassle and compromise. 

 

These two posts have done nothing to convince me that you understand what you are dealing with because you make no mention of how you intend to recharge your batteries and that, as two of us have told you, is the vital thing. If you do understand and have worked it all out I apologise.

 

How the electricity in your batteries is used, be it at 12V or 240V via an inverter is not the main issue. The main issue is how you intend to put that electricity back into the batteries on a daily basis.  Being a wide beam then given sufficient money you may well be able to fit sufficient solar for the summer months but it is unlikely that solar will suffice in the winter.

 

You CAN NOT simply take the alternator's rated output and multiply it by hours and find out how long you need to run the engine to recharge the batteries because after about the first half hour of running it is the batteries that control the charging current (not the alternator) and that charging current starts to gradually fall until many hours later - probably over 12 - it will have dropped to between 6 and 12 amps. At that time you can consider the batteries fully charged. This needs doing AT LEAST once a week unless you want to replace your batteries every ....................................... The dots could say anything from few days to year or so.

 

Over three to four hours the alternator  output may average about 50% of its rated output. From the on the average drops ad drops and drops.

 

You will also need to produce up to 30% more electricity than you took out of the batteries just to get them back to the state of charge they were in before you used any electricity. On older batteries that may be even higher.

 

Unless you start adding fancy gizmos to the alternator system that claim to recharge your batteries faster it should be almost impossible to "overload" the alternator but you may burn it out if you charge at too low revs for long periods. A gizmo may make that more likely and their overall effect in getting to full charge is questionable. They may also damage or destroy sealed batteries. Unless you properly address the recharging issue and hence your total electricity use (be it direct from 12V or via an inverter) you will be running your engine at 1200 rpm plus for many, many hours in winter.

 

The 2000 watt Sunshine inverter gives what I take to be the standby current of nearly 1 amps so that is 24 Ah of electricity used per day by just being turned on and sitting there. It will also take about 15% more electricity from the batteries than it delivers at 240 volts when its actually working so all that needs taking into account.

 

I don't want to get too technical as to the whys and wherefores because it must be confusing enough already and there is ample stuff on the forum explaining it but you need to address the recharging issue before spending money. If you do not I can assure you it will en din tears - probably your tears - and a greatly reduced wallet.

 

Link to comment
Share on other sites

23 hours ago, evilrobotshane said:

My new home was previously a floating apartment on permanent shore power, so it has a nice inverter and a decent number of 230V sockets, and basically just lights and pumps on 12V. For continuous cruising....

 

For continuous cruising your life is about to begin to revolve around how to keep your batteries charged in the first place, not whether 12v or 240v is 'more efficient' (whatever you mean by that).

 

 

 

Link to comment
Share on other sites

Young Mr. Brooks' explanation is one of the best - indeed is the best non technical description of battery charging that I have seen on here.

Congratulations!!

IM(H)O the OP should take note....

 

FWIW 540 Ah is a bit small, I'd regard 600 Ah as a bare minimum for today's usage style.

Link to comment
Share on other sites

1 minute ago, OldGoat said:

FWIW 540 Ah is a bit small, I'd regard 600 Ah as a bare minimum for today's usage style.

 

And I'd suggest the 600AH will rapidly turn into 540AH and then 300AH unless the OP has a well thought out charging regime. Which he may well have, but I m concerned he does not. 

 

 

 

  • Greenie 1
Link to comment
Share on other sites

Thanks for the concern everyone!

 

In the couple of months I’ve been aboard so far (it’s not a widebeam by the way, I’m not sure where that idea came from) I’ve been on the move a lot so the alternator alone has been more than sufficient; obviously this’ll change when things get more sedate and as has rightly been pointed out the best way for me to figure this out is to see what happens and make appropriate adjustments.

 

I’m not a heavy user of electricity, mostly just a few lights and sometimes the fridge if there’s something in it to keep cool and I have the stove going.  A television and occasional use of the washing machine, plus charging phone batteries, would all be nice but I have options ashore for sorting those problems.  I can certainly adjust my use to fit the availability, and if it turns out to be necessary, there’s options to explore like more panels, more batteries, a generator, even a wind turbine (although I gather that might be a waste of time).

 

The 2000W Sunshine inverter that draws about an Amp on standby is far more than I’d need; if what I’ve read on the topic is right, higher Wattage inverters draw more power on standby, and by my very rough estimates I’m thinking a 500W inverter would do me fine.

 

Regarding battery monitoring, I have a solar controller (EPever Tracer 30A MPPT) awaiting installation that I believe will provide the numbers to make calculations upon; finances being what they are I’m assembling the solar system bit by bit, intending to get the first panel in a few weeks, and maybe another the following month.

 

1 hour ago, Mike the Boilerman said:

whether 12v or 240v is 'more efficient' (whatever you mean by that).

 

 Apologies for not being clear; what I was getting at was whether running equivalent appliances built natively for 12V or 240V (via inverter) would differ significantly in the amount they drain the battery bank.

 

 Thanks again everyone!

Link to comment
Share on other sites

8 minutes ago, evilrobotshane said:

The 2000W Sunshine inverter that draws about an Amp on standby is far more than I’d need; if what I’ve read on the topic is right, higher Wattage inverters draw more power on standby, and by my very rough estimates I’m thinking a 500W inverter would do me fine

Don't underestimate the startup requirements of a typical 240V fridge.You may need to go higher than 500W

Link to comment
Share on other sites

30 minutes ago, evilrobotshane said:

Regarding battery monitoring, I have a solar controller (EPever Tracer 30A MPPT) awaiting installation that I believe will provide the numbers to make calculations upon; finances being what they are I’m assembling the solar system bit by bit, intending to get the first panel in a few weeks, and maybe another the following month.

Whilst the Tracer will give you some information on input from the solar panels,It will do little to advise you on battery discharge information,unless you can interpret the battery voltage reading sufficiently accurately. If you have a voltmeter and ammeter installed, this should give you more detailed info if you are able to interpret it, and help to determine when you can stop charging. Alternatively,and more costly, are shunt based battery monitors such as the Victron,Mastervolt and Nasa units. 

 

(Nope,I'm definitely not going to mention the smartgauge).

Edited by rusty69
Link to comment
Share on other sites

I am all mains, I will not be going back to the caveman 12volt I had years ago. Modern mains kit is vastly better consumption wise than it was only say five years ago due to saving the planet etc, no bad thing. My inverter is never switched off and when powering nothing uses 0.4 of an amp. As Richard says I had a poxy stirling a few years go I inherited on one of my boats that used  4 amps when doing nothing, absolutely hopeless I changed that one for a mastervolt. You need a decent monitoring device that tells you what use what when in use, my presnt one is a NASA, I have had victron and others they all tell you enough when you have worked out how to use them properly

Link to comment
Share on other sites

6 minutes ago, rusty69 said:

Don't underestimate the startup requirements of a typical 240V fridge.You may need to go higher than 500W

 

 That’s good to know, thanks; I haven’t looked into the fridge situation much yet.  Seriously considering swapping for something much smaller, I have little use for a family-size monstrosity.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.