Solar Reg. with Load disconnect- fitting where negative switched

[mikedw]

I would like to fit a solar regulator with a low voltage load disconnect to protect the house battery. I found a circuit diagram for a Morningstar Sunsaver regulator and the Low Voltage Disconnect is only on the positive - the negative is straight from the battery.
On my boat (Dehler 28s) the main switch for the house battery is on the negative, and the main fuse (35A) on the positive near the battery (10mm2 cable before, 6mm2 cable after).
At the switchboard by the chart table there is;
D: Direct negative (VHF, Shorepower charger, Diesel Heating),
-: Switched Negative (used for everything else),
+: Direct positive (VHF, Shorepower charger, Diesel Heating) and
2-20: all the individual switches for lights etc switched on the +ve side from the direct +ve feed.

I wonder how/where I should best make the alterations/ connections for the Load connection/Disconnect on the solar regulator bearing in mind it's the +ve that's switched on the regulator but negative that's switched on the boat.
I can't just move the +ve from battery to solar regulator as shore power charging etc uses it. The switchboard is on the other side of the boat from the batteries.

The only possibility I can see at the moment is running a second +ve feed from the regulator to the switch panel and splitting out the positive in the panel between what is always on (shorepower charger etc) and disconnectable.

Anyone any ideas / suggestions / help?

Here's the electrical plan which may be clearer than my description:

Hauptshalter Verbraucher = Main Switch - house battery
Efen Sicherung = Main +ve fuse (35A)
Ladegerät = Shore power charger
UKW = VHF
Heizung = Heating (Eberspächer)

 

[VicS]

[ QUOTE ]
a solar regulator with a low voltage load disconnect to protect the house battery.

[/ QUOTE ] You have lost me on this one /forums/images/graemlins/confused.gif
My brain says that a solar panel regulator would connected to a fused but unswitched +ve and an unswitched negative. My (small and regulator-less) solar panel with integral diode connects, via a fuse, directly to the battery terminals.

I have failed to grasp the concept of the low voltage disconnect to protect the battery perhaps.

EDIT That diagram was not there when i first read the post /forums/images/graemlins/shocked.gif

EDIT 2 It's all foreign /forums/images/graemlins/confused.gif /forums/images/graemlins/confused.gif

 

[mikedw]

Thanks for the reply and I'm sorry if I confused and/or surprised you - I saw one of your posts actually with an attached image and just signed up for photobucket to get the image online.

Anyway the solar regulator has
solar input +-
Battery +- (yes direct but fused +ve)
Load +- to connect the house load which disconnects when the battery is at low voltage to prevent excessive drain and protect the battery from too deep discharge

This Low voltage disconnect works by disconnecting the Load +

Morningstar SunSaver Manual

But in my case dont see how best to connect the house load /disconnect.

I hope that is a little clearer? EDIT I also added some translations from foreign just below the image.

 

[misterg]

Mike (?)

What you propose would work, but I'm at a loss to know why you would want to do it.

You'd have to split all your circuits and connect some of them direct to the battery (edit: via fuse / isolator), and some of them to the load terminal on the regulator (edit: via another fuse / isolator).

The biggest of the SunSaver regulators will only supply upto a 20 amp load.

For those that don't know these devices, they are a solar panel regulator / battery charger but with an additional set of terminals which provide regulated power from the solar panel / battery, but this cuts off if the battery voltage drops below a preset level.

Andy

 

[mikedw]

Andy,
Thanks - I thought that would be a good feature to have to protect the battery from over discharge, but it looks like it's a major job in my case. I see a lot of solar regulators have this feature, but maybe my boat is differently wired to "normal" making it more difficult to use. I estimate the absolute maximum of load if I turned everything on at once (unlikely) as 24A and the real maximum peak I could envisage sailing or anchored is 17-18A. The 20A morningstar says 25% excess for short period (5 mins) so would probably fuse this extra positive feed to the switch panel for 20-25A.

But maybe it's not worth the effort in my case. But I wonder do people not really use this feature or is my boat unusually wired? I don't know why the main battery switch(es) only switches the negative(s) rather than +ve but suppose there must be a reason.

Thanks again,
Mike

 

[misterg]

Mike,

If you're content with the load capacity of the regulator, you could just transfer your whole electrical supply from the battery to the load terminals on the regulator - it doesn't matter that the regulator cuts off +, but your isolator is in -. (Starter motor / alternator / battery charger would still need to go to the battery - I haven't studied your circuit diagram).

The down-side to this is that one dark and stormy night, you may decide that it's preferable to have a VHF / depth sounder / nav. lights / bilge pump than a partially discharged, but protected battery.

Maybe supply the fridge (if you have one) from the load terminals ??

The trend seems to be towards installing battery monitoring instruments (e.g. NASA BM1) so that one has the information to manage power consumption, and avoid nasty surprises and flat batteries.

0.02p

Andy

 

[VicS]

I have nothing to add to what misterG has said. Like him I have not studied your wiring diagram in detail. Half past midnight is not the best time for wiring diagrams especially foreign ones. /forums/images/graemlins/wink.gif

Take all your domestic load from the sun saver. Leave the existing isolator between battery and Sun saver but always leave it on. Use the load switch on the Sun saver as the normal isolator for the domestic circuits.

Will have to sort out the wiring for the alternator perhaps that might complicate matters!

I'll have another look tomorrow.

 

[VicS]

I have had another look. Still nothing much to add.

Rather than doing as I suggested earlier; take the negative connection of the regulator direct to the battery (via a switch so that it can be isolated if necessary). Leave the existing isolator to isolate the negative from the alternator and also any items that you may want to use despite a low battery state. You will have to provide a positve for them independent of the regulator as well I think.

Think all the wiring through before you buy just in case it all gets too complicated.

Reply on Monday. That'll bump the topic up to the top of the pile ready for when everyone gets back into the office after the weekend.

 

[mikedw]

Thanks Andy and VicS for your thoughts.
Seeing the feature on some solar regulators made me think it could be a useful addition, but you have confirmed my suspicions that it is a big job, and your comments made me rethink the effort/benefit. Andy's comment about better to protect us rather than the battery is a good one, and I agree it's better to have information rather than automation. So I'll leave the circuits on the usage side (I have a voltage meter in the instruments) and just add solar charging to the battery (or batteries - Am not yet decided whether to add solar charging to starter battery - mainly for winter etc). Here's my planned system/connections in case of use to anyone else. By the way I read somewhere that it is also useful to have a fuse on the -ve, but can't remember the justification.

But I am left wondering whether my boat's wiring is unusual, having the main isolation switches (and split switched/permanent) on the negative rather than positive side.

The Solar panel I bought was one in a review recently in Yachting Monthly, although they incorrectly identified it as GBSOL GBS60). I had a job trackingit down - it is actually GB-Sol 60 BL from www.gb-sol.co.uk. Comparing it with many others had a very good watts/m2 and best £/W and it's long/narrow size (1396mm x 338mm) was the perfect size to sit on top of the main drop system when moored.

Mike

 

[whipper_snapper]

I have just installed a solar reg with a similar setup. I never even considered using the 'load' terminals. All loads come from the batteries. The fridge is prevented from discharging the batteries with a fridgemate, everything else I want to have control of!

 

[Anonymous]

I don't think that this feature is of any use to you in normal cruising but could be very useful if you ever want to leave the boat for days or weeks with equipment running (diesel heating on a frost setting, fridge, security or anchor lighting, etc.). In that case, you could run a second 'low voltage protected' feed to the main bus with a changeover so that you are running in protected mode or normal mode. Instead of a switch, I'd probably use a jumper cable and physically unscrew from one terminal and make it across - after all, it is something you'd seldom use. Could be very handy in some cases. I don't let my batteries go below 12V or 11.5 as an absolute limit, and most of these things trip at 10.5V, so I probably wouldn't use it anyway.

 

[VicS]

Just a couple or three thoughts.

Are you sure it is OK to feed two solar regulators from the same solar panel? IIRC they are pulse width modulated so it probably is but I would want that confirmed. The alternative would be a single regulator with two independent outputs.

Remember that a desulphator does take a small current of its own so perhaps not suitable for connection to a battery if it will be left with no charging for longish periods.

For maintenance purposes during the winter a small solar panel of 2 watts, maybe even less, will keep the engine starter battery charged without the need for a regulator. A cheapie from Maplin propped up in a sunny window would suffice.

 

[mikedw]

One Solar Panel feeding two solar regulators is OK for the Solar Panel, and I have asked the question for the regulators.

The desulphators normally have a cut-in voltage, in my case 12.8V so they only pulse above this voltage, and my plan is to use the solar to keep the batteries charged and "pulsed".

Instead of spending £70 on a second regulator and pulser I could spend less than half on a separate small panel, but then I've got two sets of panels, cables, connections etc which gets a bit messy. Also the bigger panel should be more than capable in winter for both sets, and I get the advantage that both batteries are always topped up and pulsed.
Maybe I could just have one Reg/Pulser and in Winter just switch/reconnect to alternate batteries every month or two.

 

[mikedw]

I just had a reply from the solar regulator manufacturers about the issue VicS raised - connecting two regulators to one panel. In my case all is OK - "There isn’t any problem with your configuration. You’re splitting the current and reducing the charging capacity of the one panel, but it will work. You could, if you find that the batteries need more charging, add another panel, in line with the existing panel or have two separate systems, one panel per controller, per bank." ICP Technical Support/Customer Service

But, I suspect the answer depends on which solar controller / regulator is used. Mine is a Sunsei Charge Controller CC-10000 Sunsei Charge Controller CC-10000

I believe some solar regulators/controllers short out the solar panel when the load is not required for charging etc., which would then stop any second regulator getting any power from the panel.

So thanks VicS for the question and I think good advice would be to check for the actual regulator(s) being used if you plan a similar installation.