Boat electrics/battery/solar

[Alan de Enfield]

8 minutes ago, Chris Debois said:

Assuming it is correct to use the battery negative to take the readings, these are the numbers.

 

13.5v at alternator. (Input to splitter)

 

12.5v (output from both splitter connections)

 

So have I been unlucky to have two splitter units fitted that are not working properly?

 

I am learning, so thank you for your patience.

 

No, they are working correctly - the splitter units of that design just 'lose'1 volt whilst 'splitting'. Other types don't.

 

You have simply bought an old design rather than a newer design better technology with 'zero losses'.

 

Send it back and buy a VSR unit.

 

 

Here is one example - other manufacturers are available.

 

12v 140A Voltage Sensing Split Charge Relay / Intelligent VSR Unit - 161059 5060690920380 | eBay

Edited June 20, 2021 by Alan de Enfield

[Chris Debois]

Thank you. Can you recommend/link me to one please. Much appreciated.

 

[Alan de Enfield]

Just now, Chris Debois said:

Thank you. Can you recommend/link me to one please. Much appreciated.

 

I was doing it as you posted - see above edit.

[Chris Debois]

Many thanks Alan, I will order one now.

Best, Chris.

[Tony Brooks]

1 minute ago, Alan de Enfield said:

 

No, they are working correctly - the splitter units of that design just 'lose'1 volt whilst 'splitting'. Other types don't.

 

You have simply bought an old design rather than a newer design better technology with 'zero losses'.

 

Send it back and buy a VSR unit.

 

And wire it properly.

 

With a domestic battery well over discharged for optimum life the alternator's output voltage will be far lower than the OP seems to expect. That is normal  It's the diode volt drop that is inexcusable these days (unless it's a battery sensed alternator which it probably is not) so get the VSR and wire it properly.

[Alan de Enfield]

6 minutes ago, Chris Debois said:

Many thanks Alan, I will order one now.

Best, Chris.

 

Before you install it come back and ask for the best way to install it (and how to install it)

 

You can install it so it charges your starter battery first, and when that is full, it switches over to the domestics and charges them, or set up so it charges the domestics first and then switches over to the starter battery,

 

Many recommendations will be to have it charging the domestics first, (and there are good reasons for it), BUT, being a bit contrary I'd rather always have my starter battery fully charged knowing I can always start the engine and charge the domestics up, but if the starter is flat (or low) you cannot start the engine to charge the batteries.

 

Edit : cross posted about proper installation with Tony.

Edited June 20, 2021 by Alan de Enfield

[Tony Brooks]

Doing it Aland way is more likely to burn the relay contacts out because they will have to carry the full alternator output plus some more provided by the almost fully charged engine battery trying to charge more discharged domestic bank.

 

With a half decent engine battery, Alan's worries are not well-founded. Despite the high starting current, it's drawn for such a short time it takes only a few Ah, likely less than 10Ah so it can make many starts without any recharging. In any case, it will recharge within half an hour in most cases.

[Alan de Enfield]

11 minutes ago, Tony Brooks said:

Doing it Aland way is more likely to burn the relay contacts out because they will have to carry the full alternator output plus some more provided by the almost fully charged engine battery trying to charge more discharged domestic bank.

 

With a half decent engine battery, Alan's worries are not well-founded. Despite the high starting current, it's drawn for such a short time it takes only a few Ah, likely less than 10Ah so it can make many starts without any recharging. In any case, it will recharge within half an hour in most cases.

 

 

 

140A VSR's with 70 amp alternators

 

I did say there are good reasons not to do it my way. But, in my defence my way is the way the manufacturers suggest doing the wiring.

But, out at sea there is no 'drifting into the side', I need to ensure 100% that I have sufficient juice to start the engines, and the big 6 litre 6-cylinder engines take a big of oompf to turn over.

 

I suppose it could wire it 'your way' and use a jump lead if I did have a starter problem, and I have done that after Winter storage has left the starters a bit low but the solar has kept the domestics topped up.

 

It would be boring if we were all the same.

Edited June 20, 2021 by Alan de Enfield

[Tony Brooks]

10 minutes ago, Alan de Enfield said:

 

 

 

140A VSR's with 70 amp alternators

 

I did say there are good reasons not to do it my way. But, in my defence my way is the way the manufacturers suggest doing the wiring.

But, out at sea there is no 'drifting into the side', I need to ensure 100% that I have sufficient juice to start the engines, and the big 6 litre 6-cylinder engines take a big of oompf to turn over.

 

I suppose it could wire it 'your way' and use a jump lead if I did have a starter problem, and I have done that after Winter storage has left the starters a bit low but the solar has kept the domestics topped up.

 

It would be boring if we were all the same.

 

The red bit shows the flaw in your way of wiring. If done the way I advocate, then the solar would have charged both banks over the winter.

[Alan de Enfield]

1 minute ago, Tony Brooks said:

 

The red bit shows the flaw in your way of wiring. If done the way I advocate, then the solar would have charged both banks over the winter.

 

This last winter I actually left it with a jump lead across from the domestics to the starter. But yes, I accept you are correct in what you say.

[Tony Brooks]

Just now, Alan de Enfield said:

 

This last winter I actually left it with a jump lead across from the domestics to the starter. But yes, I accept you are correct in what you say.

 

Basically is each to their own. In any case if you had a bi-directional VSR both battery banks would have been charged.

 

I can't advise anyone to wire their system in a way that has been proven to be more likely to destroy the relay but in your way a failed relay would keep the start battery's charge but allow the domestic batteries to flatten unless you popped a jump lead on them. I would have though the VHF and navigation instruments were arguably as or more important than the engine.

[Chris Debois]

Thank you for all the advice so far. I should have mentioned previously that one of the things that happens is that when the fridge (12v Shoreline) switches on, the voltage drops to below 11v and it turns itself off again. This happens mostly at night, so I assume this is because the solar panel is not charging the batteries at this point and there isn't enough to power the fridge?

[Alan de Enfield]

8 minutes ago, Chris Debois said:

Thank you for all the advice so far. I should have mentioned previously that one of the things that happens is that when the fridge (12v Shoreline) switches on, the voltage drops to below 11v and it turns itself off again. This happens mostly at night, so I assume this is because the solar panel is not charging the batteries at this point and there isn't enough to power the fridge?

 

That again would indicate the batteries are beyond 'dead'.

During the day it will be your solar that is, in effect, running the fridge.

 

 

Fitting the new split charger will not make all of the problems go away - you will not only need to replace your batteries but will need to learn and understand how, and for how long you need to charge them to keep them fully charged.

Battery monitoring equipment is good - but again, you need to understand its limitations.

[Tony Brooks]

26 minutes ago, Chris Debois said:

Thank you for all the advice so far. I should have mentioned previously that one of the things that happens is that when the fridge (12v Shoreline) switches on, the voltage drops to below 11v and it turns itself off again. This happens mostly at night, so I assume this is because the solar panel is not charging the batteries at this point and there isn't enough to power the fridge?

 

It can indicate undersized cables from battery to fridge but in your case with the symptoms given I don't think this is the case.

[Higgs]

58 minutes ago, Chris Debois said:

Thank you for all the advice so far. I should have mentioned previously that one of the things that happens is that when the fridge (12v Shoreline) switches on, the voltage drops to below 11v and it turns itself off again. This happens mostly at night, so I assume this is because the solar panel is not charging the batteries at this point and there isn't enough to power the fridge?

 

Depending on how well your fridge is working, it will be draining your batteries over the day, 50/50 cycling, at around 36amps. The more the fridge cycle is on, the worse it gets. The average 100 Watt panel will give just over 5 amps back every hour, on a perfect summer's day; over 7 hours. to meet the demands of the fridge Unfortunately, sunny weather-wise, we're in the UK. 

 

 

 

Edited June 21, 2021 by Higgs

[Chris Debois]

So, it's the batteries?

[Alan de Enfield]

Just now, Chris Debois said:

So, it's the batteries?

 

It looks very much like it, BUT, 'it is the batteries' because they have not been charging properly because of the 'splitter'.

 

A bit like saying it is the fault of the car engine because its stopped, but, it stopped because it ran out of petrol.

[Chris Debois]

Leisure battery recommendations given it is a high days and holidays boat, not live aboard?

 

I can't be bothered going back to the chap who did the boat for me (and told me the batteries were new) so I can stomach maybe £120 per battery?

[Alan de Enfield]

1 minute ago, Chris Debois said:

Leisure battery recommendations given it is a high days and holidays boat, not live aboard?

 

I can't be bothered going back to the chap who did the boat for me (and told me the batteries were new) so I can stomach maybe £120 per battery?

 

Get cheap ones (£69) from Battery Megastore (on ebay) delivered next day.

In an ideal world get open cells (one with screw in tops so you can refill with water when needed), but many folks use sealed batteries and just treat them as disposable,

 

If you can keep them working for a couple of years you can buy expensive ones then.
You will kill expensive batteries as quickly as cheap batteries, so whilst you are learning how to look after and 'feed and maintain' them best start with cheap ones.

[Higgs]

Your batteries may be quite capable, but not if they aren't being thoroughly charged, or your cable is too narrow a gauge, over distance from the batteries to an appliance.  

 

 

Edited June 21, 2021 by Higgs

[Tony Brooks]

10 minutes ago, Higgs said:

Your batteries may be quite capable, but not if they aren't being thoroughly charged, or your cable is too narrow a gauge, over distance from the batteries to an appliance.  

 

 

 

and not if, as the OP has, a passive diode charge splitter and  a machine sensed alternator.

[Chris Debois]

14 minutes ago, Higgs said:

Your batteries may be quite capable, but not if they aren't being thoroughly charged, or your cable is too narrow a gauge, over distance from the batteries to an appliance.  

 

 

The fridge is only about 10 feet from the batteries but I'm not sure the thickness of cable. I will check next time I'm at the boat.

[Higgs]

8 minutes ago, Chris Debois said:

The fridge is only about 10 feet from the batteries but I'm not sure the thickness of cable. I will check next time I'm at the boat.

 

6mm squared cross section should be fine. But anyway, your fridge seems to be starved of power, and probably not working very efficiently. 

 

 

[Chris Debois]

Would three of these be ok?

https://www.ebay.co.uk/itm/Varta-LFD60-Leisure-Battery-12V-60Ah-Dual-Purpose-for-Caravan-Boat-Motorhome-/254811399919?_trksid=p2349624.m46890.l49286

[Tony Brooks]

39 minutes ago, Chris Debois said:

Would three of these be ok?

https://www.ebay.co.uk/itm/Varta-LFD60-Leisure-Battery-12V-60Ah-Dual-Purpose-for-Caravan-Boat-Motorhome-/254811399919?_trksid=p2349624.m46890.l49286

 

They are only 60Ah whereas typically one would expect 110Ah. If the present batteries are 60 Ah or less then they should work as well as the originals but if not then they will discharge faster than the originals when they were new.