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Designing a battery system


tonyt40

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Setting the scene - I have just bought a boat. There are few changes and improvements to make and I am sure the 12v system is one of them. It currently comprises of 6x 110ah leisure batteries that feed a distribution panel (12 way). It also feeds a ring 3100w modified sine wave inverter. The distribution panel has the usual rcd/mcb/input selector set up. Charging is done solely from the engine alternator (Beta 43 with 170a alternator). A full set of wiring diagrams came with the boat! The general wiring and cable size is fine. It has led lighting throughout, Shoreline 12v fridge freezer and other standard 12v pumps etc. There is no battery management kit that I can see.

 

The boat is to be used for leisure at the moment but hopefully in a few years will be live aboard. Obviously not wanting to completely blow the bank on this one.

 

As experienced boaters what would be your recommendations be on the battery bank set up,Charging from Shoreline / battery chargers, Battery management equipment.

 

Thanks

 

Tony

Edited by tonyt40
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Is it a reasonable assumption that you also have a 'mains hookup' (blue plug) somewhere on the outside of the boat, and, a 220v ring main ?

 

If so I would simply add in a good quality multi-stage 60 amp battery charger (eg Victron) and then 'live with' the existing systemt (be it leisure usage or liveaboard) for some time and see what the shortcomings (if any) actually are.

 

You will find enough to spend your money on without looking for solutions to problems that don't exist.


If you find that your cruising does not keep the batteries charged, then I would suggest that the 1st step would be 200+ watts of solar. The MPPT / monitor can show you battery charge state allowing you to determine if you are managing the batteries correctly

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Alan is spot on, I would add the following :-

1) Do a sanity check on the wiring to ensure the diagrams are correct.

2) Check for a Galvanic Isolator or Isolation transformer

3) Carry out a power audit.

4) Check for leakage currents etc to catch any problems early.

5) Check fuses / mcb's operate as they should.

6) Try to assess the condition of the batteries.

7) Do you have a dedicated alternator for the starter battery or a split charge system ?

 

All the above have been covered elsewhere on this forum.

Otherwise, you seem to have the basis for a good system.

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1/ Use the boat! See whether it meets your wishes. Go Boating, everything else is secondary.

 

I'd consider solar as a "start soon" project, starting with a panel to keep the engine battery charged. Boating becomes a chore when the engine doesn't start and diagnosis stops when the battery is flat.

 

Maybe I'd consider a big battery charger important as autumn approaches, -summer cruising should keep up with moderate electrical demands. For a liveaboard I'd want to install two or three options of getting enough electricity and heat over a winter, but first you've got to love the boat you have -go boating.

 

Make certain that you understand what protects the starter battery from discharge into house loads.

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Setting the scene - I have just bought a boat. There are few changes and improvements to make and I am sure the 12v system is one of them. It currently comprises of 6x 110ah leisure batteries that feed a distribution panel (12 way). It also feeds a ring 3100w modified sine wave inverter. The distribution panel has the usual rcd/mcb/input selector set up. Charging is done solely from the engine alternator (Beta 43 with 170a alternator). A full set of wiring diagrams came with the boat! The general wiring and cable size is fine. It has led lighting throughout, Shoreline 12v fridge freezer and other standard 12v pumps etc. There is no battery management kit that I can see.

 

The boat is to be used for leisure at the moment but hopefully in a few years will be live aboard. Obviously not wanting to completely blow the bank on this one.

 

As experienced boaters what would be your recommendations be on the battery bank set up,Charging from Shoreline / battery chargers, Battery management equipment.

 

Thanks

 

Tony

 

You appear to have a more than adequate capacity system just lacking a mains charger. Although relatively expensive I would consider killing two birds with one stone by replacing the the MSW inverter with a Combi consisting of say 100 amp charger and 3000 watt pure sinewave inverter. As well as providing mains battery charging it would add AC pass through to your sockets, and inverter to comfortably power a washing machine if you decide to fit one

 

You could always recoup some cost by selling on the old MSW inverter.

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I'd want some form of battery monitoring otherwise how would I know what my batteries are doing, wait for the lights to go dim?

 

Tony

 

 

On a leisure boat with six batteries and a solar panel, moored on a shore line?

 

When are the LED lights likely to go dim?!

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I think Tony is correct in suggesting some form of battery monitoring although I would just use a good quality voltmeter. I am sure it will all be fine when on the shoreline, especially if a battery charger is in use but when out cruising I do not think things are as clear, especially in view of the inverter. Not everyone cruises 6 hours a day, seven days a week, so it would be all too easy to never fully charge the batteries/over discharge them.

 

I would add a decent shunted ammeter as well to try to ensure undue fuel is not wasted when static charging.

 

I agree with Mike about the desirability of solar when away form a shoreline.

 

I would not fit an amp-hour counter gauge but encourage the OP to learn how to interpret the ammeter and voltmeter. Or maybe fit such a gauge but only use the amps and volts readings.

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When the batteries are flat, Mike wink.png

 

Possibly even more relevant - how do you know when your batteries are fully charged?

 

Tony

 

 

When arriving at the boat they bloomin' well ought to be charged having been on the shoreline since last visiting!

 

Given a marina mooring, shoreline, solar and six batteries I was thinking the boat is likely to only get day or weekend use most of the time. But I agree, no harm in adding a smartgauge too. Just that it's quite likely to be reading 100% 99% or the time.

 

Mebbe the OP could give us some info about his likely usage patterns. This would help us answer his question more accurately.

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One issue is that the OP says leisure use now, liveaboard later. the electrical requirements are significantly different for each purpose.

 

Eight hours a day of cruising will usually put enough power into the batteries for an evening watching TV, but watching TV after arriving home from work at 8pm, then going to work early will not allow any engine running til the weekend by which time the batteries may be dead (not just flat).

 

There is no point in buying lots of solar while the boat is cruising daily, If the boat is on a shoreline then a good charger is essential. Living on solar power alone in the depths of winter will need lots of panels and a sunny location for mooring.

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One issue is that the OP says leisure use now, liveaboard later. the electrical requirements are significantly different for each purpose.

 

Eight hours a day of cruising will usually put enough power into the batteries for an evening watching TV, but watching TV after arriving home from work at 8pm, then going to work early will not allow any engine running til the weekend by which time the batteries may be dead (not just flat).

 

 

Unless the OP is planning to live aboard on the mooring with the shoreline!

 

As I said earlier, we need some clarification from the OP.

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Thank you for all your replies. It does have a blue shoreline connection but no galvanic isolator so I think that is on the shopping list. I agree I think I need some form of mains charger. There are two alternators on the engine so the 170 amp is dedicated to the domestic batteries. There are volt meters on the distribution panel for both start and domestic batteries so some monitoring is available. It has a brand new start battery on it and two of the leisure batteries are also brand new. It is definitely taking a charge with the engine running. The domestic voltmeter goes up to 14.2. The engine has the "deluxe" panel with the added voltmeter and charge fail lights for both alternators. I have been running the inverter all day for tools etc and the fridge etc on with no problem. With Tony B's suggestion I think an ammeter is a good idea.

 

I had a good look down the bilge today. There are two battery isolators fitted between the start and domestic and their respective alternators but nothing on the outputs from the domestic to the inverter and the 12v distribution. I think it probably needs two more. Am I correct?

 

Our usage this year is likely to be weekends and 3 single weeks at the moment. It is moored on a standard towpath mooring at the moment with no mains so our only source of mains is a generator.

 

I have a small solar panel (30w) and charge controller from my caravan that I will put on when not is use to keep the starter battery charged. I will look to a proper solar system in the long term.

 

I suppose the main consideration is buy a charger or swap the inverter for a pure sine wave combination unit? There is a washer on the boat but it's never been connected or plumbed (the skin fixing hoses at are still in the bags). I suppose the question is how much do I want to spend? If the washer doesn't work with the inverter it's not a big problem at the moment, I will just have to use it with the generator or find somewhere with a shore connection.

 

If it's just a charger will some of the cheaper options do? Say a 30a sterling? Spending the rest of the money on solar? Obviously it will take longer to charge but the batteries would get a balance of alternator and overnight mains. Generally when the boat is used we will be cruising and when it's not everything power using will be isolated.

 

OK so this is my plan (until it changes) :-

1. Test condition of 4 older batteries

2. Fit battery isolators

3. Price up a mains charger - I think I will keep the inverter I have for now.

4. Fit a galvanic isolator for if I ever get mains!

5. Enhance the battery monitoring - basic smart gauge or other options (ammeter or nasa?) based on cost.

6. Price up a solar system - my only concern with towpath motoring is that somebody might nick the panels!

 

Any further comments greatly appreciated.

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....................... Obviously it will take longer to charge but the batteries would get a balance of alternator and overnight mains.

 

Where will you be getting the 'overnight mains' ?

 

You have no hook-up on your bank-side mooring so are you looking at producing the mains via the generator ?

 

I am sure you know that you should not (cannot) run a generator between the hours of 8pm and 8am.

 

Given that you already have an inverter I would go for a 'separate' battery charger, if you have a combi unit and 'one side' fails you 'lose the lot', with separates you still have one working.

There are some advantages of having a combi (notably the capability to support a low current supply with a top up from the batteries) but, for me, its 'seperates' every time.

You can buy just a £200 charger instead of a £1000 combi unit. You would not recoup anywhere near the difference by selling the existing inverter (maybe get £100 on ebay ?)

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Where will you be getting the 'overnight mains' ?

 

You have no hook-up on your bank-side mooring so are you looking at producing the mains via the generator ?

 

I am sure you know that you should not (cannot) run a generator between the hours of 8pm and 8am.

It was based on "find somewhere with a shore connection" that I had mentioned further up. I am not a fan of generators anyway I just happen to own one from before I had the boat.

 

I go with your comments over charger / combination. Any recommendations in the £200 bracket.

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It was based on "find somewhere with a shore connection" that I had mentioned further up. I am not a fan of generators anyway I just happen to own one from before I had the boat.

 

I go with your comments over charger / combination. Any recommendations in the £200 bracket.

 

In my experience there are very, very few places you can 'just turn up and find a shoreline connection' (visitors berths in marinas, the end of the Llangollen, odd moorings on the River Trent). They are extremely uncommon on the canal system. I think you should plan on battery charging by cruising, or, occasional use of the generator.

 

Having looked at Charger prices, I seem to be a 'bit out of date' A quality brand such as a Victron Centaur 60a appears to be £350.

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It is moored on a standard towpath mooring at the moment with no mains so our only source of mains is a generator.

 

 

 

This changes EVERYTHING!

 

As other have said, mains hook ups out and about are virtually non-existent so all battery charging needs to be solar/engine/genny.

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In my experience there are very, very few places you can 'just turn up and find a shoreline connection' (visitors berths in marinas, the end of the Llangollen, odd moorings on the River Trent). They are extremely uncommon on the canal system. I think you should plan on battery charging by cruising, or, occasional use of the generator.

 

Having looked at Charger prices, I seem to be a 'bit out of date' A quality brand such as a Victron Centaur 60a appears to be £350.

Do you have a link? £350 for a 60a Victron is very cheap.

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Another option :

 

Midland Chandlers : http://www.ebay.co.uk/itm/Waeco-Perfectcharge-12-Volt-50-Amp-Battery-Charger-MCA1250-Narrowboat-Caravan-/272203750976?hash=item3f609b9e40:g:FN4AAOSw8d9U0Ks0


Do you have a link? £350 for a 60a Victron is very cheap.

 

You are correct - having looked again (very closely) that is excluding VAT, so it comes out at around £430.

 

Tricky blighters some of the chandleries.

 

However, the Waeco one at £265 includes VAT and delivery - that is good value.

 

The difference in charging times between a 50 amp and a 60 amp is probably only a matter of a few minutes, as very little time is actually spent charging at full rate, and then only on 'flat batteries'. As soon as the batteries get 'a bit' of charge in them the current drops and you will find that you are actually putting in (maybe) 10 amps for many hours, rather than 50 or 60 amps for an hour. (its the way batteries 'work')

Edited by Alan de Enfield
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Another option :

 

Midland Chandlers : http://www.ebay.co.uk/itm/Waeco-Perfectcharge-12-Volt-50-Amp-Battery-Charger-MCA1250-Narrowboat-Caravan-/272203750976?hash=item3f609b9e40:g:FN4AAOSw8d9U0Ks0

 

 

You are correct - having looked again (very closely) that is excluding VAT, so it comes out at around £430.

 

Tricky blighters some of the chandleries.

 

However, the Waeco one at £265 includes VAT and delivery - that is good value.

 

The difference in charging times between a 50 amp and a 60 amp is probably only a matter of a few minutes, as very little time is actually spent charging at full rate, and then only on 'flat batteries'. As soon as the batteries get 'a bit' of charge in them the current drops and you will find that you are actually putting in (maybe) 10 amps for many hours, rather than 50 or 60 amps for an hour. (its the way batteries 'work')

£430 is still cheap. Link please.

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It was based on "find somewhere with a shore connection" that I had mentioned further up. I am not a fan of generators anyway I just happen to own one from before I had the boat.

I go with your comments over charger / combination. Any recommendations in the £200 bracket.

Just so you know, opinion is split over the Combi vs the seperates concept. We have a Combi and it is great because it all works seamlessly. It is perhaps outside your price bracket but I would get a mastervolt Combi since these are the most reliable (also most expensive, but you tend to get what you pay for!). If you are worried about the failure issue then you could keep the current inverter "mothballed" as a backup. You would still have the engine alternator for battery charging.

 

If we ever got another boat, I would definitely want another Combi. Combis also do a "power support" thing whereby they can add to the incoming shore or genny power so that for example they could use battery and/or alternator power to supplement a genny that couldn't quite cope with the washing machine's heating element being on at the start of the wash cycle.

 

I know that Mastervolt kit is expensive but on the other hand, when electronics supplying the basics like mains power fails, it always happens at the worst time and "buy cheap, buy twice" springs to mind. You've spent a lot on the boat, why skimp on the core electrical systems?

Edited by nicknorman
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