Battery advice?

[moomba]

Are you sure you didn't?

the Battery cable running from the parallel batteries to the distribution box or via the battery isolation will be capable of taking that 200 amps from the batteries it is them distributed around the boat, the OP stated we will run the fridge in a hot country longer , therefore MORE AMPS are demanded , I also stated that if the OP WANTED to extend his electrical power then there is more demand on his cable and to add larger cable gives him redundancy if they desire
now the OP needs to work out his total amps draw at the largest draw know he is drawing more power
If his main lead to the battery isolate switch is capable of taking 150 amps but now the OP needs 200 AMPS because his fridge is drawing more power at peak times then the OP needs to check that Cable size
All this is theoretical and is down to the OP doing a spread sheet of his total amounts of amps used at peak time add an extra safety margin and change his cables accordingly (IF NEEDED)

I hereby say for the last time this is advisory , and the OP needs to do his checks to see his cables are able to take the extra amperage , fuse at the battery source and good luck
As for the South Coast Mafia good to see you boys again missed you , I wonder how many of you have re wired several boats
And I d aplogise if this was not made clear and for my outburst , I feel sometime the usual grey society think that anything out of their dialogue or thinking is wrong and like a pact of ancient wolves that cant give up jump on , I am afraid it is the usual suspects get a life guys

 

[pvb]

the Battery cable running from the parallel batteries to the distribution box or via the battery isolation will be capable of taking that 200 amps from the batteries it is them distributed around the boat, the OP stated we will run the fridge in a hot country longer , therefore MORE AMPS are demanded , I also stated that if the OP WANTED to extend his electrical power then there is more demand on his cable and to add larger cable gives him redundancy if they desire
now the OP needs to work out his total amps draw at the largest draw know he is drawing more power
If his main lead to the battery isolate switch is capable of taking 150 amps but now the OP needs 200 AMPS because his fridge is drawing more power at peak times then the OP needs to check that Cable size
All this is theoretical and is down to the OP doing a spread sheet of his total amounts of amps used at peak time add an extra safety margin and change his cables accordingly (IF NEEDED)

I hereby say for the last time this is advisory , and the OP needs to do his checks to see his cables are able to take the extra amperage , fuse at the battery source and good luck
As for the South Coast Mafia good to see you boys again missed you , I wonder how many of you have re wired several boats
And I d aplogise if this was not made clear and for my outburst , I feel sometime the usual grey society think that anything out of their dialogue or thinking is wrong and like a pact of ancient wolves that cant give up jump on , I am afraid it is the usual suspects get a life guys

You should take Tranona's advice (in his very restrained reply to your insult) and try to learn the difference between amps and amp-hours. You clearly don't know what you're talking about and therefore it would be better not to keep posting advice on a subject you don't understand.

 

[RupertW]

the Battery cable running from the parallel batteries to the distribution box or via the battery isolation will be capable of taking that 200 amps from the batteries it is them distributed around the boat, the OP stated we will run the fridge in a hot country longer , therefore MORE AMPS are demanded , I also stated that if the OP WANTED to extend his electrical power then there is more demand on his cable and to add larger cable gives him redundancy if they desire
now the OP needs to work out his total amps draw at the largest draw know he is drawing more power
If his main lead to the battery isolate switch is capable of taking 150 amps but now the OP needs 200 AMPS because his fridge is drawing more power at peak times then the OP needs to check that Cable size
All this is theoretical and is down to the OP doing a spread sheet of his total amounts of amps used at peak time add an extra safety margin and change his cables accordingly (IF NEEDED)

I hereby say for the last time this is advisory , and the OP needs to do his checks to see his cables are able to take the extra amperage , fuse at the battery source and good luck
As for the South Coast Mafia good to see you boys again missed you , I wonder how many of you have re wired several boats
And I d aplogise if this was not made clear and for my outburst , I feel sometime the usual grey society think that anything out of their dialogue or thinking is wrong and like a pact of ancient wolves that cant give up jump on , I am afraid it is the usual suspects get a life guys

Please just stop - when you post things like "taking those 200 amps from the batteries" because the batteries are 200 Ah now, it just shows that you think that things that sound alike must be the same. I've looked and can't find any links basic enough for you to understand - not because it's complicated but you seem to have a complete inability to learn from what others are explaining. Most people on here including me have had many half-thought pieces of knowledge and find the forum very helpful for pointing us in the right direction and working out who actually knows what they are talking about.

You must be winding us up, please. At least that way I don't have to imagine the way your boat must be wired to cope with those 3 12 volt batteries giving out 36 Amps.

 

[Moderator]

Closed pending review.

Opened. Action taken.

Moderator

 

[Quandary]

My Battery Project, advice sought?

I started a thread hoping for some help, got some replies which surprised me, a spat developed and I am now more confused than ever. My response to the info. was rejected because the thread is closed but I am even more in need of technical help now.
I hope anyone who can assist will still be willing to give me technical advice, hopefully I can sift any contradictions so there should not be any need for it to get personal.
To summarize, I intend to add a battery as an engine/ windlass battery and combine the two existing batteries as a domestic bank.
So- 1. I was advised that I must replace the two existing batteries, I did not buy them but they seem to be of similar physical size and capacity so what happens if I do not?
2. I intended to run the windlass off the engine battery, this is not the first boat I have had with this arrangement, provided I continue to only use the windlass when the engine is running why put that load on the domestic side?
3. I suspect that my existing spare battery is too tall and the terminals position would require the positive lead to be extended so instead I propose to spend around £80 on a Varta Blue E12 74ah. which is lower with handed terminals so will fit the optimum position centred just behind the existing pair under the aftcabin berth. Not happy as I am a cheapskate.
4. My plan was to use the existing positive lead to the domestic battery(D+) with a new short link to the positive on the old engine battery (E+) the negative from the old engine battery would remain with a link from the domestic, this correct?
5. Cable sizing, I had hoped to continue to use the existing cables with just a new negative from the new engine battery to the busbar in the engine compartment, the windlass negative already runs to this bar. The new links and new engine neg. would be of tinned cable from Planet, similar size to the existing (40mm?) or a size up, I think Planet only offer 35 or 50mm. I have a hyrdraulic crimper previously used for rigging wire.

I would hope that the protagonists and everyone else would be willing to advise me of any errors I am making, where you might disagree I am happy to make my own judgement so keep cool and think of how you might help this numpty.

 

[Moderator]

Re: My Battery Project, advice sought?

Since the original thread is reopened I've merged the new one with it, to avoid duplication with the aim of helping...

 

[RichardS]

Wow .... total carnage in such a short time. That's got to be some kind of record fallout for YBW?

Richard

 

[pvb]

Re: My Battery Project, advice sought?

To summarize, I intend to add a battery as an engine/ windlass battery and combine the two existing batteries as a domestic bank.
So- 1. I was advised that I must replace the two existing batteries, I did not buy them but they seem to be of similar physical size and capacity so what happens if I do not?

You don't have to replace the 2 existing batteries, as long as they're both similar type (ie flooded lead/acid, maintenance free lead/acid, etc) so that they require the same charging voltage. You've said they're both 100Ah. Ideally, they ought to be of a similar age, but it isn't that important.

2. I intended to run the windlass off the engine battery, this is not the first boat I have had with this arrangement, provided I continue to only use the windlass when the engine is running why put that load on the domestic side?

The windlass would be better if it were fed from the domestic bank, for the simple reason that an engine battery should be dedicated to the engine. If you generally have the engine running when using the windlass, the alternator will be feeding the domestic bank.

3. I suspect that my existing spare battery is too tall and the terminals position would require the positive lead to be extended so instead I propose to spend around £80 on a Varta Blue E12 74ah. which is lower with handed terminals so will fit the optimum position centred just behind the existing pair under the aftcabin berth. Not happy as I am a cheapskate.

There wouldn't be any problem in extending the positive battery cable, as long as you make a decent connection and use the same size cable. Naturally, you'd be careful to insulate the join. You say your existing Numax battery is described as a "starting and leisure" battery, so it should cope with starting a small diesel engine.

4. My plan was to use the existing positive lead to the domestic battery(D+) with a new short link to the positive on the old engine battery (E+) the negative from the old engine battery would remain with a link from the domestic, this correct?

It would be OK. Some purists might argue that you should take the main positive and negative leads from opposite ends of the battery bank, but with just 2 batteries it's not essential.

5. Cable sizing, I had hoped to continue to use the existing cables with just a new negative from the new engine battery to the busbar in the engine compartment, the windlass negative already runs to this bar. The new links and new engine neg. would be of tinned cable from Planet, similar size to the existing (40mm?) or a size up, I think Planet only offer 35 or 50mm. I have a hyrdraulic crimper previously used for rigging wire.

Assuming you're not planning to run substantially heavier electrical loads, your existing cables should be fine. New links should be at least the same size cable as the existing. For safety, you should ideally add a fuse in the main positive leads of the engine battery and domestic bank; these should be as close to the batteries as possible. I'm quite fond of MegaFuses, which also have robust fuseholders, and I'd suggest a 250A fuse in each one. These are purely to prevent a fire in the unlikely event of a short-circuit in the main cables.

 

[geem]

Re: My Battery Project, advice sought?

You don't have to replace the 2 existing batteries, as long as they're both similar type (ie flooded lead/acid, maintenance free lead/acid, etc) so that they require the same charging voltage. You've said they're both 100Ah. Ideally, they ought to be of a similar age, but it isn't that important.



The windlass would be better if it were fed from the domestic bank, for the simple reason that an engine battery should be dedicated to the engine. If you generally have the engine running when using the windlass, the alternator will be feeding the domestic bank.




There wouldn't be any problem in extending the positive battery cable, as long as you make a decent connection and use the same size cable. Naturally, you'd be careful to insulate the join. You say your existing Numax battery is described as a "starting and leisure" battery, so it should cope with starting a small diesel engine.



It would be OK. Some purists might argue that you should take the main positive and negative leads from opposite ends of the battery bank, but with just 2 batteries it's not essential.



Assuming you're not planning to run substantially heavier electrical loads, your existing cables should be fine. New links should be at least the same size cable as the existing. For safety, you should ideally add a fuse in the main positive leads of the engine battery and domestic bank; these should be as close to the batteries as possible. I'm quite fond of MegaFuses, which also have robust fuseholders, and I'd suggest a 250A fuse in each one. These are purely to prevent a fire in the unlikely event of a short-circuit in the main cables.

Excellent advice PVB

 

[dolabriform]

Re: My Battery Project, advice sought?

Excellent advice PVB

+ 100

 

[RupertW]

Re: My Battery Project, advice sought?

+ 100

Concur

 

[Quandary]

Re: My Battery Project, advice sought?

pvb
I appreciate you taking the trouble to address the issues I was concerned about, I will take the advice on board when I get back to things tomorrow. The vertical clearance for the battery I have is marginal because of the slope of the locker floor which rises diagonally but I may make up a box long enough to take the lower profile battery but try the existing one in it before rejecting that option. I will look at Megafuses.
I am grateful for all contributions and will read through all of them again tomorrow before proceeding. Thank you.

 

[PaulRainbow]

Re: My Battery Project, advice sought?

The windlass would be better if it were fed from the domestic bank, for the simple reason that an engine battery should be dedicated to the engine. If you generally have the engine running when using the windlass, the alternator will be feeding the domestic bank.

I usually prefer to connect the windlass to the engine battery, always have. With many sdetups it might not make much difference these days, but if i have to use a little power on the windlass it may as well come from the engine battery, leaves as much as possible in the domestics. Unlikely to discharge the engine battery, as the engine should be running, there should be an emergency start switch anyway, If the engine is running, both banks should be charging.

For safety, you should ideally add a fuse in the main positive leads of the engine battery and domestic bank; these should be as close to the batteries as possible. I'm quite fond of MegaFuses, which also have robust fuseholders, and I'd suggest a 250A fuse in each one. These are purely to prevent a fire in the unlikely event of a short-circuit in the main cables.

Mega fuses are good, but need an extra cable making up, not the end of the World. 12v Planet cube fuses are also worth considering.

Other than those couple of personal preferences, all good advice :encouragement:

To the OP ;

Don't forget you'll need some form of split charging (please don't say you're fitting a 1-2-Both switch).

An emergency start switch is a good idea.

If you have to buy a new engine battery, i think these are good value : https://www.batterymegastore.co.uk/...batteries/boat-batteries/hankook-sa57020.html

 

[William_H]

OP should firstly determine if the battery he has proposed to use as an engine start battery is still good for high current engine start. (by starting the engine with it.) If it is no good then he should purchase a suitable engine start battery with correct lead orientation.
Re this argument re higher currents. The domestic batteries will be double the Amp hour capacity. There will be some increase in charge current but if we assume the existing leads ware heavy enough to carry engine start current then there is no concern re able size. However to concede, if there was short on the domestic wiring the max short circuit current could indeed double possibly incandescing the wiring where previously the wiring may have taken the max current from one battery. So perhaps more need than ever for a fuse in the domestic wiring of a rating to protect the wiring. OP will however need to provide some way of starting the engine off the domestic batteries which will require heavy wiring often not fused. ol'will

 

[pvb]

However to concede, if there was short on the domestic wiring the max short circuit current could indeed double possibly incandescing the wiring where previously the wiring may have taken the max current from one battery.

Bearing in mind the fact that a shorted battery can easily deliver around 1000A, it's unlikely that the existing wiring would have been able to take the current without melting. Fuses are important on any installation, regardless of how many batteries are fitted.

 

[Quandary]

I had assumed that the boat must have split charging already and all I was doing was increasing the capacity of one bank as simply as possible? Can it have two separate banks even of only one battery each without split charging?
The Cube fuses look neat but at £17 a connection on the expensive side, is there a convention regarding sizing v battery cable capacity? I presume I could get away with one per bank rather than one per battery? Quite a lot of boats do not appear to have fused battery cables but it would make sense to take this opportunity to fit them I suppose.
The boat has three separate main switches, (Moodys used to be commissioned with just one battery, the second was an option) In the panel at the chart table - domestic, under the panel - engine, and near the batteries, - the Eber (now Planar) heater. These are all the plastic turn key type. The documentation with the boat implies that there may be a BEP device somewhere, not found it yet.

Another query, what is the best (easiest) way to determine the size of the existing cable, originally I was guessing by appearance but after all the debate I was planning to measure the diameter of the core using a micrometer?

 

[Pasarell]

As another Moody owner I suggest you also post a question like this on the owners forum. Advice here is usually good when you sift through it but on the MOA forum you get it without all the exciting side issues! I missed the whole thing until now and would make 2 points. First, I agree with advice from PVB. Second, how on earth did Tranona get banned? That has to be crazy.
Anyway, having nearly suffered a fire through engine start cables shorting (abrasion not overload) on another boat I would strongly advocate fuses near the battery banks. If you have to lengthen the leads to the new start battery that seems an obvious place to install the fuse if possible. My engine is an MD22L and probably bigger than yours. My start battery is a 27AH Odyssey that is tiny. Been in place for at least 5 years and starts the engine instantly. As it's AGM it can be mounted at any angle so may fit well with the side of the hull if space is tight. Not cheap and there are other equivalents but in my case it freed up space for another domestic battery.
I think cable size is normally marked on the outside casing at regular intervals. Worth checking before getting the micrometer out.

 

[ghostlymoron]

I think there's a battery fuse that fits directly on the battery terminals thus eliminating any unprotected cable. I'll see if I can find the details.

 

[pvb]

I think there's a battery fuse that fits directly on the battery terminals thus eliminating any unprotected cable. I'll see if I can find the details.

They're called "cube fuses", as mentioned by PaulRainbow in post 37.

https://www.12voltplanet.co.uk/battery-terminal-cube-fuses-50-300a.html

(...other suppliers are available!)

 

[geem]

Re: My Battery Project, advice sought?

I usually prefer to connect the windlass to the engine battery, always have. With many sdetups it might not make much difference these days, but if i have to use a little power on the windlass it may as well come from the engine battery, leaves as much as possible in the domestics. Unlikely to discharge the engine battery, as the engine should be running, there should be an emergency start switch anyway, If the engine is running, both banks should be charging.

For our installation, having the windlass powered from the domestic battery makes more sense. The windlass has a 1700w motor. The domestic batteries are 1000amp/hr so the load on the domestic batteries whilst the windlass is running is minor compared to a 1700w load running for a few minutes to recover 200ft of chain via the engine battery. With the engine on tick over the alternator is not putting significant amps in to the batteries so certainly doesnt cover the discharge whilst using our windlass. We dont charge the engine battery other than by solar and or the Duogen. (Both have dual outputs for engine and domestic banks.) Since it only does a 1/2second discharge to get the engine started it really doenst need the alternator output so for us an automatic system is unnecessary such as a VSD. In an emergency we just connect the domestic bank to the engine battery via a switch. This set up wont work for everybody but its perfect for us.