12v appliances when on shore power

[alexmh1985]

hi guys, this is my first post! took delivery of a sailaway a few weeks ago, just getting to the stage of the electrics. It will be mainly a 12v boat, lights, fridge, tv etc. my question is - if I am hooked up to shore power are the batteries still feeding the 12v items whilst being charged? or does the inverter / charger systems feed the 12v while hooked up to the mains? (i am yet to purchase the inverter / charger).

 

Thanks in advance!

[OldGoat]

Plain answer is "Yes".

The normal practice is for the inverter / charger to charge the batteries - from which you then run whatever 12V equipment you want to use.

Some inverter charger s will run as a pure power supplies without batteries being involved (that is if you haven't bought them yet) but it would restrict you in what charger you bought, so best to ignore that option.

Some items may exceed the power available from the charger anyway so best to have Charger > batteries > equipment.

 

Without it could be a Micawber solution

 

 

 

Edited September 16, 2018 by OldGoat

[Alan de Enfield]

9 minutes ago, alexmh1985 said:

hi guys, this is my first post! took delivery of a sailaway a few weeks ago, just getting to the stage of the electrics. It will be mainly a 12v boat, lights, fridge, tv etc. my question is - if I am hooked up to shore power are the batteries still feeding the 12v items whilst being charged? or does the inverter / charger systems feed the 12v while hooked up to the mains? (i am yet to purchase the inverter / charger).

 

Thanks in advance!

In effect your battery charger is powering your 12v appliances and what ever is 'left' goes into the batteries.

If you are using something drawing more current than the battery charger can supply, this additional requirement will be provided by the batteries.

 

If you are having a 'decent sized' marine multi-stage battery charger (say 50 amps +) then I cannot think of any 12 volt appliance that would require additional power from the batteries.

 

If using something requiring high power, (washing machine etc) then presumably that would be running on 'mains' via the shore-line (230v)

[Momac]

My fridge is dual voltage so when on shore power there is no current flowing through the batteries .  I have often wondered if the dual voltage is necessary but it does potentially allow the battry charger to be off while keeping the wine or beer  chilled.

Otherwise my charger is left on full time  while hooked up.

I don't have an inverter.

[b0atman]

A wise person has separates. Separate inverter if needed and a separate battery charger.All eggs in one basket is not a good idea when one has a problem.

[nicknorman]

10 minutes ago, b0atman said:

A wise person has separates. Separate inverter if needed and a separate battery charger.All eggs in one basket is not a good idea when one has a problem.

I disagree. I am a wise person and I don’t have separates. Most boats have alternate means of 12v charging such as engine or solar. If an inverter or Combi fails, you lose ac power when off shore power, doesn’t matter whether it is a separate or a Combi. If you have a Combi and it fails, yes you lose the charger too but then you have alternate means of keeping the batteries charged so it isn’t a big deal.

 

What is gained from a Combi is seamless switching between shore power and inverter, much less wiring faff, no need for manual changeover switches etc and an ability for the AC system to provide more power than the shore breaker or generator limit.

 

Therefore I consider this “must have separates” argument to be ill conceived and generally just a parroting of something someone else said, without actually having done any analysis of the facts.

[Tony Brooks]

17 minutes ago, nicknorman said:

Therefore I consider this “must have separates” argument to be ill conceived and generally just a parroting of something someone else said, without actually having done any analysis of the facts.

And having thought long and hard about the subject my conclusion is that unless you want a floating cottage which has little appeal to me and I do not consider boating then having a combi is just as ill conceived.

 

There are situations where the alternative forms of charging are NOT available because CaRT notices and good manners prevent engine running and solar (if you have it) has insufficient output.

 

Horse for courses and each to their own, neither option is the correct and only one.

[alexmh1985]

Thanks guys I thought that was the case but just wanted to make sure! Getting some cables in today

[Alan de Enfield]

7 minutes ago, alexmh1985 said:

Thanks guys I thought that was the case but just wanted to make sure! Getting some cables in today

 

 

Just remember the BSS requirements for spacing/installation of electrical cables and gas piping.

[b0atman]

real case boat in marina  inverter went faulty so combined inverter charger sent away for repair owners watched lights die out one night.Running engine in marina ?

 

[alexmh1985]

That's a diesel line for the stove next to the water pipes but I'll read up on the regs!

[nicknorman]

22 minutes ago, b0atman said:

real case boat in marina  inverter went faulty so combined inverter charger sent away for repair owners watched lights die out one night.Running engine in marina ?

 

People run their engines in our marina, so I don’t see the point? Your exact same argument applies if you have a separate charger and it goes faulty, so having separates doesn’t remove this issue.

[Alan de Enfield]

30 minutes ago, nicknorman said:

People run their engines in our marina, so I don’t see the point? Your exact same argument applies if you have a separate charger and it goes faulty, so having separates doesn’t remove this issue.

Yes it does, with a combi you have to send away a perfectly good charger if the inverter goes down.

31 minutes ago, nicknorman said:

People run their engines in our marina,

So its not just you that's 'weird'.

 

Who would run an engine to charge their batteries when there is cheap elec available ?

[mrsmelly]

My twopenneth. This boat has an all singing and dancing combi that wipes yer nose for you if you want. Would I have fitted it..... Not on yer Nellie, separates every time for me. But don't let my judgement colour your judgement as I don't live in a house so don't understand what it's all about.

[Alan de Enfield]

7 minutes ago, mrsmelly said:

My twopenneth. This boat has an all singing and dancing combi that wipes yer nose for you if you want. Would I have fitted it..... Not on yer Nellie, separates every time for me. But don't let my judgement colour your judgement as I don't live in a house so don't understand what it's all about.

 

Had a combi on one boat - never again 'separates' for me as well.

[Robbo]

5 hours ago, b0atman said:

A wise person has separates. Separate inverter if needed and a separate battery charger.All eggs in one basket is not a good idea when one has a problem.

why? a charger and inverter don’t do the same thing so it isn’t really putting everything in one basket!   A combi brings a few benefits especially if you have a generator.   Another is the cost of a decent separate charger and inverter is much more.

[Stilllearning]

Everything separate and useage as low power as possible, so LED lights etc. Decent inverter so you can recharge laptops etc, and at a pinch run something that needs mains power, but try to avoid this. Stove with back boiler for radiators, and heating your domestic hot water, and when walking back to the boat and you pass a nice looking piece of potential firewood in a skip or hedge, grab it and take it home to burn. Living on a boat CAN be expensive, but one can make it a lot cheaper with some forethought.

Have fun!

[Dr Bob]

5 hours ago, nicknorman said:

I disagree. I am a wise person and I don’t have separates. Most boats have alternate means of 12v charging such as engine or solar. If an inverter or Combi fails, you lose ac power when off shore power, doesn’t matter whether it is a separate or a Combi. If you have a Combi and it fails, yes you lose the charger too but then you have alternate means of keeping the batteries charged so it isn’t a big deal.

 

What is gained from a Combi is seamless switching between shore power and inverter, much less wiring faff, no need for manual changeover switches etc and an ability for the AC system to provide more power than the shore breaker or generator limit.

 

Therefore I consider this “must have separates” argument to be ill conceived and generally just a parroting of something someone else said, without actually having done any analysis of the facts.

Our victron combi was our way to do things.....but let us down badly last year. Moored in the marina for a couple of weeks last winter. Power on the pontoon went off and then came on again. Unfortunately the combi didnt come back on - it was in the battery charger position so wouldnt flatten the batteries with the inverter in case of a power loss.  Therefore no power to the boat for 10 days.....lucklily it wasnt too cold so electric rads not needed. Not sure what the problem was with the combi.

We therefore rewired so shore power goes to the 240v system WITHOUT going through the combi. Installed a cheap victron 30a charger and use the combi for inverter duty only. Separates are much better due to this example. No problem with the combi in inverter mode this year.

[Sea Dog]

1 hour ago, Dr Bob said:

Our victron combi was our way to do things.....but let us down badly last year. Moored in the marina for a couple of weeks last winter. Power on the pontoon went off and then came on again. Unfortunately the combi didnt come back on - it was in the battery charger position so wouldnt flatten the batteries with the inverter in case of a power loss.  Therefore no power to the boat for 10 days.....lucklily it wasnt too cold so electric rads not needed. Not sure what the problem was with the combi.

We therefore rewired so shore power goes to the 240v system WITHOUT going through the combi. Installed a cheap victron 30a charger and use the combi for inverter duty only. Separates are much better due to this example. No problem with the combi in inverter mode this year.

Which is almost exactly my experience with my (iirc the very same as Nicknorman's) Mastervolt Combi. I'm now running Victron separates. 

[peterboat]

1 hour ago, Dr Bob said:

Our victron combi was our way to do things.....but let us down badly last year. Moored in the marina for a couple of weeks last winter. Power on the pontoon went off and then came on again. Unfortunately the combi didnt come back on - it was in the battery charger position so wouldnt flatten the batteries with the inverter in case of a power loss.  Therefore no power to the boat for 10 days.....lucklily it wasnt too cold so electric rads not needed. Not sure what the problem was with the combi.

We therefore rewired so shore power goes to the 240v system WITHOUT going through the combi. Installed a cheap victron 30a charger and use the combi for inverter duty only. Separates are much better due to this example. No problem with the combi in inverter mode this year.

Richards a mates combi went down just the inverter part however it couldnt be repaired so he had it as just a charger, and he bought a seperate inverter to go with it. However not long afterwards the battery charger part went down as well!! so that has been replaced with just a battery charger, so over a period of years he has ended up with two seperate items by default and now considers it the best anyway

Edited September 16, 2018 by peterboat

[nicknorman]

Anything can go wrong. An inverter can go wrong. A charger can go wrong. A Combi can go wrong. Is there any data that shows a Combi is inherently less reliable than an inverter or a charger? I don’t think so! Reliability of such gadgets is probably mostly determined by brand and even more by luck. Our Combi has been on nearly continuously for over 7 years so even if it does go wrong (which of course is an inevitability given enough time) I consider that the convenience far outweighs any (alleged, and backed by no evidence) claims that separates are more reliable.

[nb Innisfree]

Cost apart how about 2 combis? Doesn't take much more space than separates with the advantage of double the back up. 

[Dr Bob]

12 minutes ago, nb Innisfree said:

Cost apart how about 2 combis? Doesn't take much more space than separates with the advantage of double the back up. 

How about 4? Quadrouple the back up.

[WotEver]

32 minutes ago, Dr Bob said:

How about 4? Quadrouple the back up.

Any advance on 8?

[Sea Dog]

27 minutes ago, nicknorman said:

Anything can go wrong. An inverter can go wrong. A charger can go wrong. A Combi can go wrong. Is there any data that shows a Combi is inherently less reliable than an inverter or a charger? I don’t think so! Reliability of such gadgets is probably mostly determined by brand and even more by luck. Our Combi has been on nearly continuously for over 7 years so even if it does go wrong (which of course is an inevitability given enough time) I consider that the convenience far outweighs any (alleged, and backed by no evidence) claims that separates are more reliable.

Mastervolt also do separates, so it seems reasonable that their similar quality kit is similarly reliable. Doesn't it therefore follow that each element in one box containing a charger and an inverter is approximately as likely to go wrong as a charger and inverter pair in separate boxes? So  the inverter/charger gets 2 bites of the unreliability cherry and a catastrophic failure of either element is likely to be fatal to the combined unit. Whilst perhaps no less likely, such a failure would affect only one element of the separates. That's the real issue with Combi V Separates: inherently similar reliability per element, but it's the eggs in the same basket thing.  There is, however, other stuff in a Combi which, convenient though it may be, is another link in the chain. In my case (you may recall) it was the transfer circuitry, so my Inverter worked but on only the one of the 2 outputs and the charger didn't work at all.  A quick shuffle of the wiring and a stand alone Ctek charger kept me going, so it certainly wasn't the doomsday scenario some foresee. 

 

I was very happy with my Mastervolt Combi until what I believe was a shore power issue took it out and I was considering replacing like for like.  What I was less keen on was zero technical support from Mastervolt and the diagnosis (let alone repair) procedure being return to the Netherlands with an uncertain outcome thereafter.  Them writing it off, scrapping it and offering a 20% discount on full RRP of a new one didn't seem a good deal. The worst a shore power issue could do to my new Victron set up is damage the charger at about 1/20th the cost of that Combi, although I suspect the stand alone charger is more robust.  The cost in terms of convenience is a hand changeover switch and a lack of a battery support in the case of an inadequate shore power facility (which I never used), so although it's no longer a single switch operation as it was with he Combi I don't feel I have lost out too much.  

 

I certainly don't want to place my flag in the die-hard separates camp, and I don't lament the demise of wind up windows in cars either, but when faced with enforced Combi replacement the appraisal came out in favour of separates for me, and not just because the price was halved.  I expect, in similar circumstances, you'd do a similar appraisal and possibly even reach a similar conclusion.