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robtheplod

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On 19/01/2023 at 13:55, robtheplod said:

The battery isolator has three pins, one input (where the mains charger and starter alternator connect) and two outputs, one to the starter battery and one to the BT battery, so the batteries are isolated from each other. I'm fairly sure one cant drain the other...

 

The isolator is this one: Sure Power 702 Multi Battery Isolator 70A 1 Input 2 Battery : Amazon.co.uk: Automotive

 

Not that it matter if you are happy, but that is not what we generally call a battery isolator. It looks suspiciously like a passive split charge diode that will drop up to 0.6 on both its outputs. That probably matters little to the engine battery, but the bow thruster with long cable runs is a different matter. I also suspect that a drawn it does not comply with the BSS (no isolator switches for the engine and bow thruster batteries).

 

You are right, when working the batteries can't drain into the other.

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1 minute ago, robtheplod said:

Yes  :)  i was however surprised that it still worked whilst covered.....

I bought a deck brush at the market, it was £6.50, but it does the panels, the roof, and the floor inside the boat. I was wary of pouring very warm water on the panels, they were very cold.

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How does connecting a start battery or BT batteries to the domestics work in terms of setting up the solar controller? If you simply connect your start battery to the domestics with a jump lead then you've effectively increased the size of the bank and presumably need to set this up on the controller (or does the Victron MPPT automatically detect capacity?)

 

I assume connecting additional battery banks via a VSR is no different in terms of effectively increasing the battery bank size? I'd have thought doing this isn't without its disadvantages? If the VSR switches to charge the start battery before the domestics have fully charged for example, and the sunshine is limited so the domestics never get charged I can see that as a downside. For a liveaboard, demand from the domestic bank will always be greater so charging the domestics should always take priority and anything which detracts from that isn't good in my opinion. 

 

Conversely, one's start (and BT) batteries should always be fairly close to fully charged after cruising or being charged from shore power/battery charger, so they can sit off charge for some time without a problem. My start and BT batteries haven't been charged for about 10 days. The BT batteries are currently sitting at 12.8v and the start battery is at 12.5v. The start battery is about 6 years old so probably due for replacement soon. If it dies I have a parallel switch between my start & domestic battery isolators.

 

The other thing to think about if you're charging multiple banks from a single charger or controller (even with multiple 12v outputs), is whether the battery chemistry of those different banks are all the same type (open lead/acid, sealed, gel, AGM, etc)? If not you could be undercharging or overcharging one of the banks. I know nothing about lithium batteries so I'm not including them in this post.

Edited by blackrose
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9 hours ago, Puffling said:

Looks good. How are they attached to the roof, do I spy magnets there?

You do indeed. This is why it took me so long to sort this as i was looking for a good way to fix without drilling. These seem fine, with 20kg pull each the panel is pretty much rock solid. I wanted to get the panels as low profile to the roof as possible to try to avoid wind issues, and these sit under the height of the mushrooms. Time will tell of course if these turn out to be viable and I'll probably be sweating when its windy, but early signs are good. Note my roof is 'smooth' so this helps!

 

rubber.PNG

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41 minutes ago, robtheplod said:

You do indeed. This is why it took me so long to sort this as i was looking for a good way to fix without drilling. These seem fine, with 20kg pull each the panel is pretty much rock solid. I wanted to get the panels as low profile to the roof as possible to try to avoid wind issues, and these sit under the height of the mushrooms. Time will tell of course if these turn out to be viable and I'll probably be sweating when its windy, but early signs are good. Note my roof is 'smooth' so this helps!

 

rubber.PNG

Ours have been held on with magnets for years without being blown away. I did get a bit nervous one very blowy day and put some coal bags on the edges of the panels, but I'm sure they weren't required. 

 

Keep an eye on the paint beneath the magnets,ours began to rust. 

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1 hour ago, robtheplod said:

You do indeed. This is why it took me so long to sort this as i was looking for a good way to fix without drilling. These seem fine, with 20kg pull each the panel is pretty much rock solid. I wanted to get the panels as low profile to the roof as possible to try to avoid wind issues, and these sit under the height of the mushrooms. Time will tell of course if these turn out to be viable and I'll probably be sweating when its windy, but early signs are good. Note my roof is 'smooth' so this helps!

 

rubber.PNG

I was a little concerned for my panels during gusty winds in October on the Caldon, but the magnets didn't budge. All the same, I took a precautionary spare mooring rope over the top of all three panels during the worst night, tightened between mushroom  vents.

 

I used very similar magnets to the ones you seem to have chosen and I am much more relaxed about them now. The panels have been on my roof since July, mounted flat and to one side the same as yours. The rope security might come out again if we face a storm in the Eunice category, but aside from that I'm happy with the four-point attachment. 

29 minutes ago, rusty69 said:

Keep an eye on the paint beneath the magnets,ours began to rust. 

Very good point, I did wonder when I installed them.

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5 minutes ago, Puffling said:

I was a little concerned for my panels during gusty winds in October on the Caldon, but the magnets didn't budge. All the same, I took a precautionary spare mooring rope over the top of all three panels during the worst night, tightened between mushroom  vents.

 

I used very similar magnets to the ones you seem to have chosen and I am much more relaxed about them now. The panels have been on my roof since July, mounted flat and to one side the same as yours. The rope security might come out again if we face a storm in the Eunice category, but aside from that I'm happy with the four-point attachment. 

Very good point, I did wonder when I installed them.

I suppose i could shuffle the panels every now and again to keep an eye on rust... :)

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I've been giving more thought to the wiring now i have solar. My Invertor is old and too small and my battery charger is suspect so thinking if i eventually change to a invertor/charger how this might also change things. I'll assume the new Invertor/Charger just has a single output for a battery charger (MultiPlus II etc). Reading about the Victron ArgoFet battery isolator this seems to have less loss than my current unbranded one so might be beneficial?

 

So, looking below at my new diagram. its just looking at + connections, ignoring all fuses/isolator switches etc at this stage.

 

My thinking....

 

Engine Running

 

leisure alternator charging leisure batteries + passing ArgoFet to charge Bow Thruster battery. unavoidably also charging starter battery by passing ArgoFet (unsure currently if this is workable as the starter alternator is directly charging it already or am i over thinking this??)

 

starter alternator charging just the starter battery

 

Engine not running

 

Solar/Battery charger charging leisure batteries + passing ArgoFet to charge Bow thruster battery and also the Starter Battery.

 

 

Any opinions on this gratefully received!!

 

rob

potential wiring.png

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On 23/01/2023 at 16:49, robtheplod said:

I've been giving more thought to the wiring now i have solar. My Invertor is old and too small and my battery charger is suspect so thinking if i eventually change to a invertor/charger how this might also change things. I'll assume the new Invertor/Charger just has a single output for a battery charger (MultiPlus II etc). Reading about the Victron ArgoFet battery isolator this seems to have less loss than my current unbranded one so might be beneficial?

 

So, looking below at my new diagram. its just looking at + connections, ignoring all fuses/isolator switches etc at this stage.

 

My thinking....

 

Engine Running

 

leisure alternator charging leisure batteries + passing ArgoFet to charge Bow Thruster battery. unavoidably also charging starter battery by passing ArgoFet (unsure currently if this is workable as the starter alternator is directly charging it already or am i over thinking this??)

 

starter alternator charging just the starter battery

 

Engine not running

 

Solar/Battery charger charging leisure batteries + passing ArgoFet to charge Bow thruster battery and also the Starter Battery.

 

 

Any opinions on this gratefully received!!

 

rob

potential wiring.png

 

If  the "battery isolator" is the one in your  earlier image than I don't think it will work because it is almost certainly a passive split charge diode that work because the alternator output that is connected to the "in" stud can pass through dioses to charge the both batteries but neither battery can push currant BACKWARDS through the diodes.

 

If you intend to buy another one from Victron then you have two cables missing from the diagram, the ones that power the electronics in the splitter. I think that it might work as you suggest, but would advise that you talk to Victorn about it. The last thing you want to do is destroy a new bit of kit by trying to back feed the engine alternator charging voltage into it.

 

Much depends upon how you intend to energise it.

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2 minutes ago, Tony Brooks said:

 

If  the "battery isolator" is the one in your  earlier image than I don't think it will work because it is almost certainly a passive split charge diode that work because the alternator output that is connected to the "in" stud can pass through dioses to charge the both batteries but neither battery can push currant BACKWARDS through the diodes.

 

If you intend to buy another one from Victron then you have two cables missing from the diagram, the ones that power the electronics in the splitter. I think that it might work as you suggest, but would advise that you talk to Victorn about it. The last thing you want to do is destroy a new bit of kit by trying to back feed the engine alternator charging voltage into it.

 

Much depends upon how you intend to energise it.

thanks Tony, yes it is the victron kit. i was looking at it as the losses are less than the current kit. I will attempt to chat to victron.

Argofet Battery Isolators - Victron Energy

 

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cheers Tony, I must admit the more i look into this the i'm coming to the same conclusion......  I was just curious if i could wire it somehow so the solar that now charges my leisure batteries could automatically also charge the others, but this seems like its a no go. Back to the jumper lead and a good memory!

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57 minutes ago, robtheplod said:

cheers Tony, I must admit the more i look into this the i'm coming to the same conclusion......  I was just curious if i could wire it somehow so the solar that now charges my leisure batteries could automatically also charge the others, but this seems like its a no go. Back to the jumper lead and a good memory!

 

Unless it has had it, the engine battery should always be well charged, even after several months of no charge, so one way would be to put a VSR between the domestic and bow thruster battery. If you wanted to, you could then fit another between the engine and domestic bank, and then connect both to the battery negative (the thin black cable) via a switch. With the switch off it would all work as now, but with the switch on all battery banks would be charged whenever the voltage from a charger or the solar was high enough.

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