Solar panel

30boat said:
I'm installing a 25W solar panel on my boat.I've got a simple regulator off Ebay
http://www.ebay.co.uk/itm/360684563165?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2648.
How do I wire it to my two batteries?Any tricks I should know of?
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Refer to the users manual but basically:

Solar panel to the terminals indicated for the solar panel

two terminals indicated as the battery connection to the battery, or battery bank, you wish it to charge..... but fit a fuse rated, to protect the wiring, as close as possible to the battery connection.

Ensure your wiring is adequately sized for the max likely current to prevent excessive volts loss over the length of of the wiring from panel to battery. 2.0mm² is likely to be adequate for any run length within a 30ft boat.

Be aware that it is just a basic on/off controller. Not a regulator. It simply disconnects at 14 volts ( 13.7 v ??? ) and reconnects at an unspecified lower figure. You'll not get the performance that you would from a PWM regulator

Use the load terminals if you want it to control a load within the parameters in the spec. ( off if the volts fall below 10.8, back on when they rise above 11.8)
 
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30boat said:
I'm installing a 25W solar panel on my boat.I've got a simple regulator off Ebay
http://www.ebay.co.uk/itm/360684563165?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2648.
How do I wire it to my two batteries?Any tricks I should know of?
Click to expand...

You won't connect it to your two batteries if you have a battery isolator and use the two batteries seperately. I tried! By wiring the charger directly to the two batteries you find that with either battery switched on it will draw power from the other as well and when starting it will draw enough current through the solar charge controller to 'pop' the controller. If you then fit another but this time make a 'Y' lead to go from the charger to the two batteries with a Diode in each lead between the 'Y' and the battery it eventually pops the charge controller. (I blew two so you don't have to....)

This one is designed for two batteries and I have one fitted - So far so good :)

http://www.ebay.co.uk/itm/141107861...X:IT&_trksid=p3984.m1497.l2649#ht_2037wt_1190
 
Big-Bang1 said:
You won't connect it to your two batteries if you have a battery isolator and use the two batteries seperately. I tried! By wiring the charger directly to the two batteries you find that with either battery switched on it will draw power from the other as well and when starting it will draw enough current through the solar charge controller to 'pop' the controller. If you then fit another but this time make a 'Y' lead to go from the charger to the two batteries with a Diode in each lead between the 'Y' and the battery it eventually pops the charge controller. (I blew two so you don't have to....)

This one is designed for two batteries and I have one fitted - So far so good :)

http://www.ebay.co.uk/itm/141107861...X:IT&_trksid=p3984.m1497.l2649#ht_2037wt_1190
Click to expand...
Thanks all,I'll get one of these then. http://www.ebay.co.uk/itm/141107861...X:IT&_trksid=p3984.m1497.l2649#ht_2037wt_1190
Until then I'll just connect my basic controller to one battery at a time just to get by.What size fuse should I fit?Sorry about the basic questions .
 
I have fitted 10 amp inline fuses between each charge lead from charger to batteries.

On my Fathers boat he's just fitted a single controller like the one you have to his battery number 1. His theory is battery number 1 will/should always be charged ready to start the engine and the engine will then charge battery number 2. I'd still rather maintain both batteries.
Hope this helps
Big-Bang1
 
30boat said:
.What size fuse should I fit? Sorry about the basic questions .
Click to expand...

The fuse must be smaller than the max safe current rating of the wiring. It is there to protect the wiring from the very high current that the battery could supply in the event of a short circuit.

10 amp will be fine if you use anything over about 1.0mm² cable. The fuse should be as close as possible to the battery connection

Do you intend powering anything from the "load" terminals
 
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Almost certainly that Kemo charge splitter uses 2 silicon diodes which will drop .7 volt in the feed to each battery or if it has schotky diodes they will drop about .25 volts. Either way you will not get a full charge from the solar controller. `
Best then is a dual outlet controller or 2 controllers one for each battery from one panel or just connect the 2 batteries hard wired in parallel. good luck olewill
 
William_H said:
Almost certainly that Kemo charge splitter uses 2 silicon diodes which will drop .7 volt in the feed to each battery or if it has schotky diodes they will drop about .25 volts. Either way you will not get a full charge from the solar controller. `
Best then is a dual outlet controller or 2 controllers one for each battery from one panel or just connect the 2 batteries hard wired in parallel. good luck olewill
Click to expand...

What if I connect the leads to one battery and leave the battery switch to both?Will that work?
 
Most people just connect the solar to the domestic battery and leave the engine battery to look after itself. The latter should always be fully charged after a few minutes running. If not, you need a new starter battery. The only situation where you could need to charge it is if you have very long periods in between engine starts.
If you parallel the batteries, you run the risk of draining both batteries if one is defective. Then you won't be able to start your engine.
 
30boat said:
What if I connect the leads to one battery and leave the battery switch to both?Will that work?
Click to expand...

It will work but there are two reasons not to do that.

One that that Ghostly moron mentions namely you might end up with two flat batteries if one is defective.

Secondly if the switch is set to "both" power is on to all the boat circuits defeating the object of an isolator switch.
 
VicS said:
It will work but there are two reasons not to do that.

One that that Ghostly moron mentions namely you might end up with two flat batteries if one is defective.

Secondly if the switch is set to "both" power is on to all the boat circuits defeating the object of an isolator switch.
Click to expand...
Good point!
 
William_H said:
Almost certainly that Kemo charge splitter uses 2 silicon diodes which will drop .7 volt in the feed to each battery or if it has schotky diodes they will drop about .25 volts. Either way you will not get a full charge from the solar controller. `
Best then is a dual outlet controller or 2 controllers one for each battery from one panel or just connect the 2 batteries hard wired in parallel. good luck olewill
Click to expand...

It keeps my batteries up ok.
If 14 odd volts are across the input then I'm happy with 13 odd across the batteries ;)
 
The idea of fuses right at the battery as opposed to at the controller is to protect the actual wire controller to battery. This wire will almost certainly burn if there is a short +ve to-ve ie at the controller terminals if they come loose. The fuse rating should be adequate for the expected charge current and more than adequate (rated less than) for the current rating of the wire.
The question of diode volt drop after the controller is interesting. When we are talking alternator charging batteries it is important.
When we are talking solar charging it may not matter so much. Take a 20w solar panel ie good for 1 amp of charge. If the battery is just sitting in the boat it probably has a voltage of about 12 .5 volts. ie not really flat but not fully charged. The controller limits the output voltage to 14v. Then we lose .7 volt in the didoes. You have 13.3 volts to push 1 amp into the battery. This is quite likely to be doable. So battey will recieve as much charge as is possible from the panels. However if we try to push more amps (bigger panel) into a smaller battery the voltage needed to do that will increase as will the inherent voltage of the battery and you may find that the full charge can not be acheived before the controller and diode limit the voltage available for charge so actual charge current. It would be interesting to see actual results. olewill
 
volt drop on Kemo charge splitter

LadyInBed said:
It keeps my batteries up ok.
If 14 odd volts are across the input then I'm happy with 13 odd across the batteries ;)
Click to expand...

I measured a difference of 0.03 Volts between the input and output of the Kemo device from Maplins. This was using my half-decent DVM so should be close enough.
Not bad for a fiver!

cheers

Rum Run
 
William_H said:
The question of diode volt drop after the controller is interesting. When we are talking alternator charging batteries it is important.
When we are talking solar charging it may not matter so much. Take a 20w solar panel ie good for 1 amp of charge. If the battery is just sitting in the boat it probably has a voltage of about 12 .5 volts. ie not really flat but not fully charged. The controller limits the output voltage to 14v.
Click to expand...

Only the very crudest controllers are quite that simple. Once you exceed the heady heights of a tenner on eBay, the controller is sensing the battery voltage and using that to decide what current to stick into it. If you put a diode in the way the controller will always overestimate the battery voltage by 0.7V, resulting in a heck of an undercharge. Precisely the same problem, of course, affects machine-sensed alternators when split charge diodes are used.
 
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