Solar Panel - two batteries...how to wire?

[E.T.]

I've got the panel (30W), the regulator and the wire...it's simple to do in theory, however...

Anyone got any advice the best way to connect up?

I have two batteries, 80Ah for the engine (battery 1), 110Ah deep discharge for everything else (battery 2). There is a manual change over switch, so I can switch to Battery 1, 2 or both.

So when I wire the panel in do I wire to this switch, and then manually choose to charge 1, 2 or both? (giving the option to charge either battery...or both.

Supposing battery 1 is full but battery 2 is quite low...when I switch to "both" I assume 1 will drain into 2, to equalise (and vice versa, of course).

Whats the best philiosophy to adopt when using boat batteries? and where do I stick my charge from the solar panel??


Thanks

 

[rogerthebodger]

Maplin have a regulator that connects one solar panel to 2 batteries.

http://www.maplin.co.uk/dual-16a-solar-charge-regulator-266145

 

[VicS]

An good suggestion from Roger

Note the requirement to fit a 16A fuse.

I'd feel tempted to fit separate fuses at the connections to each of the batteries, especially if the regulator is not adjacent to the batteries

 

[Chalker]

I'd just connect it to the services battery.
Unless you have a really difficult to start engine the discharge when starting is very little (very high current for very short time) and will recharge in minutes of engine run.
That way you can turn off all of the loads when you leave the boat and leave the controller and panel to do their job.
As below (above? elsewhere?) make sure it's fused controller to battery, rating to suit the cable used.

 

[E.T.]

yes intend fitting a fuse of course - should be within 150mm from the battery I read.

I think I may wire into the change over switch, which mostly will be on "2", ie the leisure battery - just gives the option of charging "1" if I want by switching over.

Any reason I should avoid this? (its going through a PWM controller BTW)

 

[VicS]

yes intend fitting a fuse of course - should be within 150mm from the battery I read.

I think I may wire into the change over switch, which mostly will be on "2", ie the leisure battery - just gives the option of charging "1" if I want by switching over.

Any reason I should avoid this? (its going through a PWM controller BTW)

Check the installation instructions for the controller.

IIRC some require the battery to be connected before the solar panel.

If that is the case then it probably rules out connecting via a switch

 

[contessaman]

Maplin have a regulator that connects one solar panel to 2 batteries.

http://www.maplin.co.uk/dual-16a-solar-charge-regulator-266145

just fitted this unit to my boat.

60w panel
240 ah domestic bank
110 ah starter battery.

each output thru a 5 amp fuse close to battery. (mounted regulator+fuses on side of battery box)
all working well, the regulator seems to be well made and good value for money.

 

[dedwards]

My boat's previous owner had fitted a separate switch to allow choosing which battery to charge.

However, I second Chalker's suggestion to just wire to the leisure battery. If you want to charge the engine one, just set your selector to 'Both'.

I should mention that the ideal method is to dump your 1,2,both switch and then install a voltage sensing relay with dual sense capability.

 

[BAtoo]

I put a panel on last year - 20W directly onto 140AH domestic battery via an on-off regulator - seems to be working well in keeping it charged. Ignored charging the engine battery as its a small RedFlash & can start off the domestic in an emergency.

We'll see when I try starting the engine after a winter lay-up.......

 

[E.T.]

thanks for the replies.

i went back to sunshinesolar.co.uk, and they have a similar unit to the maplin one suggested (only better - marine quality. . . er . . . marinated?) and although it costs more than my original, they are sending it to me, and when i get i can send back the original ( unused) controller.

must say i'm impressed with their customer service!

 

[lw395]

I'd just connect it to the services battery.
Unless you have a really difficult to start engine the discharge when starting is very little (very high current for very short time) and will recharge in minutes of engine run.
......

I disagree, particularly if you don't use the engine much in the winter. A battery will benefit from a small trickle charge, as it never fully charges from a short period of running. Perhaps a 5 or 10W panel just for the engine battery would be good. This certainly made a huge difference to a friend's boat, an extra bit of charge in the battery made it much more willing to start in cold weather, we'd thought a new battery was going to be needed.