How To Get Solar Panel Wired ?

[Sea Dog]

1 hour ago, NewCanalBoy said:

Well curiousity got the better of me and I temporarily wired it up. Has settled down to 2.5 A input.

 

I guess it is working and although it is not a big amount it is better than nothing - and apart from a charger unit it was FREE !!

 

 

What you need to bear in mind is that the battery will only draw the charging current it needs. If your batteries are full, you'll see very little current on the brightest of days, no matter the capacity of your solar array. Have a look at the display when the fridge kicks in and, particularly, see what it's doing in the morning when you have had an evening's use out of your batteries and they're hungry!

[NewCanalBoy]

On 16/07/2019 at 17:33, Tony Brooks said:

Connections:  Pos & neg wires from controller to the battery with whichever side has the battery master switch on it connected to the BATTERY side of the switch

Could you try and explain this to me again please ? Haven't quite grasped it !

[Alan de Enfield]

2 minutes ago, NewCanalBoy said:

Could you try and explain this to me again please ? Haven't quite grasped it !

You have a battery 'master switch' (probably with a big red-plastic-key)

The wires go from the battery to one side of the switch, (Normally the positive, but occasionally some wire it into the negative wire

The wire from the other side of the switch goes off to the RCD / Fuse box or "somewhere in the bowels of the boat".

 

You have two wires coming from the solar ( + & -)

If the battery master switch is in the Positive line then connect the solar positive (+) to the side of the switch that the battery is connected to.

 

If the switch is in the negative line, connect the solar negative to the battery side of the switch.

 

Basically this means that you can never disconnect the output from the solar controller (if you do it will burn out - this is why it must be on the 'battery side' of the switch and not the 'load side' of the switch.

 

If you ever need to work on the solar panels or the batteries ALWAYS DISCONNECT THE SOLAR PANELS FROM THE CONTROLLER NOT THE CONTROLLER FROM THE BATTERIES.

[NewCanalBoy]

Why can't I just connect the solar out put wires to the battery ?

[Alan de Enfield]

4 minutes ago, NewCanalBoy said:

Why can't I just connect the solar out put wires to the battery ?

You can (suitably fused)

I was just answering your question.

 

 

I have done just that, but it is considered 'best practice' not to, & to just have a single wire going to / from the battery and avoiding the 'spaghetti' that appear on some boaters battery terminals.

Put your wires at opposite ends of the battery bank - not both on the same battery.

[NewCanalBoy]

I see thank you.

 

I just had a guy onboard who was servicing the engine/box and he told me I could put the output from the solar charger onto the service terminal on the splitter. Doesn't sound right does it ?

[Alan de Enfield]

27 minutes ago, NewCanalBoy said:

I see thank you.

 

I just had a guy onboard who was servicing the engine/box and he told me I could put the output from the solar charger onto the service terminal on the splitter. Doesn't sound right does it ?

I'd prefer not to comment.

I am getting accused of being negative and argumentative so I'm working on the 'If you don't have anything nice to say, say nothing' principle.

Edited July 30, 2019 by Alan de Enfield

[NewCanalBoy]

Ok. Going back to your earlier comment regarding 'if the solar charger has nowhere to output it will burn out' - or something similar.

 

If there is an in line fuse by the battery and it blows won't that do the same thing and burn the panels out ?

[Tony Brooks]

30 minutes ago, NewCanalBoy said:

I see thank you.

 

I just had a guy onboard who was servicing the engine/box and he told me I could put the output from the solar charger onto the service terminal on the splitter. Doesn't sound right does it ?

Now tell us what this "splitter" actually is. If its a 1,2,both, off switch then bets not to if you want all your batteries charged when its turned off. If its a split charge relay then no, it wont work without the ignition on. If its a VSR (Voltage Sensitive Relay) then yes but if you choose the wrong main terminal it will only charge one bank. If its a split charge diode then probably best not to because they drop maybe half a volt across them. If its an electronic beast like a so called zero drop diode then it depends what you mean by "service terminal". It should go to the terminal that is connected to the battery bank you wish to charge as long as there are no isolator switches between that terminal and the battery.

 

More info needed to get you a better answer.

 

50 minutes ago, NewCanalBoy said:

Why can't I just connect the solar out put wires to the battery ?

 

You can but as Alan says it is bad practice.  Your wires are almost certainly not silver coated or tinned strands so the close you get them to the battery the more chance there is of acid fumes working their way into the cable and gradually corroding it.

 

 

[Alan de Enfield]

1 minute ago, NewCanalBoy said:

Ok. Going back to your earlier comment regarding 'if the solar charger has nowhere to output it will burn out' - or something similar.

 

If there is an in line fuse by the battery and it blows won't that do the same thing and burn the panels out ?

Yes - (It will damage the controller, not the panels), but something more serious will have happened 'upstream' to have made the fuse blow.

[Tony Brooks]

5 minutes ago, NewCanalBoy said:

Ok. Going back to your earlier comment regarding 'if the solar charger has nowhere to output it will burn out' - or something similar.

 

If there is an in line fuse by the battery and it blows won't that do the same thing and burn the panels out ?

I think Alan may have been overstating the danger to a degree but many if not most solar controller instructions say that you MUST always connect the batteries before the controller. We recently had a discussion on here as to why this may be because the manufactures have failed to explain it. My suspicion is that the controller may set itself to 24 volts but others disagree.

 

To follow on from Alan's last answer #51. The absolute bottom line is that if teh fuse blows you may damage the controller but without the fuse whatever caused it to blow may well set fire to the boat.

Edited July 30, 2019 by Tony Brooks

[NewCanalBoy]

22 minutes ago, Tony Brooks said:

Now tell us what this "splitter" actually is. 

It's one of these !!

[Tony Brooks]

13 minutes ago, NewCanalBoy said:

It's one of these !!

 

Which is? Maker, model etc.

 

 

If the blue part of the case is finned then it is almost certainly an ordinary passive split charge diode serving three battery banks by the look of it. Unless you have a battery sensed alternator or an advanced controller that converts your alternator to battery sensing then your charging system is already compromised by voltdrop. However the black wires I take to be negative are unusual on a passive split charge diode so it may be an electronic zero voltdrop unit.

 

You have three terminals with two red wires on each. Connect your solar to whichever is connected to the battery bank you want to charge. It is unlikely to charge any other bank. If there is a battery master switch between that unit and the battery then you need to connected the solar charging to the BATTERY side of that switch. If there is a single master switch in the negative then the solar charging negative cable should be connected to the BATTERY side of that switch.

Edited July 30, 2019 by Tony Brooks

[NewCanalBoy]

It says VETUS Diode 126-3 but I can't find anymore info on it.

 

Of all the manuals that came with the boat it's the only one I'm missing !!

[NewCanalBoy]

If I turn the battery master switch to the OFF position then I still have current passing through those terminals on the photo above.

[Tony Brooks]

29 minutes ago, NewCanalBoy said:

It says VETUS Diode 126-3 but I can't find anymore info on it.

 

Of all the manuals that came with the boat it's the only one I'm missing !!

The later incarnations of that unit suggests it is a 120 Amp unit splitting betwen three battery banks. It also appears to be a zero voltdrop active device.

 

 

23 minutes ago, NewCanalBoy said:

If I turn the battery master switch to the OFF position then I still have current passing through those terminals on the photo above.

How are you measuring that. Where have you connected each voltmeter lead.

 

"The battery master switch" (singular) implies it in the negative side of the circuit so if you are measuring between one of the studs and a battery negative post it would show as live. If you changed the meter negative lead to the SWITCHED (non-battery) side of a negative master switch then with the switch turned off the supply would also turn off.

 

One problem is we haven no real idea how your particular boat is wired. I try to work from the way things are normally done but yours might be different. If the battery negatives have been connected to the hull on the battery side of the master switch ten I very much doubt it is BSS compliant but don't worry too much about that for now, just get the solar working.

[NewCanalBoy]

I bought some cable from a chandlery which was 8.75 amp wire. Looks a bit weedy but as I'm going to go nowhere near half that currently I assume that is OK ?

I bought some 5amp and 10 amp fuses, I was going to stick a 5 amp in my fuse holder.

Does it all sound OK ?

[WotEver]

21 minutes ago, NewCanalBoy said:

I bought some cable from a chandlery which was 8.75 amp wire. Looks a bit weedy but as I'm going to go nowhere near half that currently I assume that is OK ?

Probably not, no. 8.75A cable would be 0.75mm². I’d be wanting 4mm² or even 6mm². 

http://www.smartgauge.co.uk/cable_type.html

[Tony Brooks]

Oh dear.  Once again for cable sizing for 12V DC work you need to ignore anything written on the drum in respect of amps and calculate the CCSA required to minimise voltdrop based on cable run length, CCSA and amps to flow.

 

Fuses basically protect cables so there is no way you can use a 10 amp fuse with cable rated at 8.5 amps. The five am one will be OK as long as it is not so close to the maximum current flow it suffers thermal stress and breaks early.

 

My catalogues do not list 8.5 amp cable. The smallest is 0.5 sq mm CCSA cable and that is rated at 11 amps and I doubt it has enough strands to meet modern practice. 1 sq mm CCSA cable is rated at 16.5 amps but most of us I suspect on a SHORT run of a couple of meters would use 2 sq mm CCSA cable rated at 25 amps for mechanical strength. Have you bought bell or speaker cable?

 

 

[Chewbacka]

42 minutes ago, NewCanalBoy said:

I bought some cable from a chandlery which was 8.75 amp wire. Looks a bit weedy but as I'm going to go nowhere near half that currently I assume that is OK ?

I bought some 5amp and 10 amp fuses, I was going to stick a 5 amp in my fuse holder.

Does it all sound OK ?

Cable current rating is based on a safe current, ie will not overheat the cable.  Now at mains voltages with a ‘thin’ cable you may loose say 5% in the cable (so 5% of 220v is 11v) so if you loose 11v in the cable that still leave 209v at the appliance, so no problem.  BUT that same current at 12v will still loose 11v in the cable, which means you only have 1v at the appliance, so it won’t work.  Hence 12v circuits need thick cables, and the longer the cable the bigger the loss so even thicker cable is required to reduce the loss.

 

so the cable you need depends upon your system voltage (probably 12v), the length of cable, the current the load requires and how much you are prepared to loose in the cable.  That’s why people use on line cable calculators as it’s too hard to do it in your head.

Edited July 30, 2019 by Chewbacka

[WotEver]

24 minutes ago, Chewbacka said:

That’s why people use on line cable calculators as it’s too hard to do it in your head

Or you can use the rough’n’ready ‘divide by three’ method for runs of only a few metres. So 9A - 3mm², 12A - 4mm² etc to get you in the ball park. 

[NewCanalBoy]

Right, just found this in my toolbox !! Is this going to get me by for now ?!

 

 

[matty40s]

2 minutes ago, NewCanalBoy said:

Right, just found this in my toolbox !! Is this going to get me by for now ?!

 

 

You have a good toolbox!

[Chewbacka]

I think that Halfords cable is 2 sq mm 

 

so using the divide by 3 rule of thumb above, good for 6A - so long as it’s only a few metres there and back.

Edited July 30, 2019 by Chewbacka

[Alan de Enfield]

12 minutes ago, Chewbacka said:

I think that Halfords cable is 2 sq mm 

 

so using the divide by 3 rule of thumb above, good for 6A - so long as it’s only a few metres there and back.

It is 2mm2.

The make up is 28 stands of 0.3mm wires manufactured to BS6862 "Automotive Cables"

 

Will be OK is the run length is no more than 2mts from battery controller,

 

Go and buy some 8mm² and do the job correctly and do it once.