Solar panel controller

[fishermantwo]

I have two solar 40w panels, two batteries and two of these solar controllers. The idea being to have one panel and controller for each battery wired direct and not through the two way switch. Do I just wire the battery and output terminals together on the controller or just leave the output terminals bare?

 

[VicS]

Connect the solar panel to the terminals for the solar panel.

Connect the battery directly to the terminals shown for the battery

The load terminals are for a load that you want to be able to run even with the battery isolator off.
If it runs the battery too low the controller will disconnect it until the sun shines again and the solar panel recharges the battery.
Its described as "overdischarge protection" in the bumph

If you have no requirement to use that feature do not connect anything to those terminals

You could have bought similar controllers without the feature

You do realise these are just simple controllers that disconnect the panel when the battery is charged and reconnect it when the volts fall again?

They are not "Pulse Width Modulated" regulators or "Maximum Power Point Tracking" regulators

 

[fishermantwo]

Connect the solar panel to the terminals for the solar panel.

Connect the battery directly to the terminals shown for the battery

The load terminals are for a (small) load that you want to be able to run even with the battery isolator off.
If it runs the battery too low the controller will disconnect it until the sun shines again and the solar panel recharges the battery.

I guess I could use the load terminals to keep the radio presets.

 

[VicS]

I guess I could use the load terminals to keep the radio presets.

Yep could do I guess

Fit a small fuse

You are fitting fuses to the battery connections too I hope... close to the battery to protect all the wiring

 

[donm]

Solar panels

Just bought two solar panels from Maplins - one 2.4 w for the boat cranking battery, and one 12 w for the motorhome cranking battery (as it has an alarm etc so flattens quicker). Both batteries are 80 Ah and in good nick.

So, a few questions

1. Can I permanently wire them into the battery rather than use croc. clips or cigar lighter connections?
2. If they are permanently wired in, do I need to protect the panels from power surge when the engine is started?
3. Do I need controllers to protect the batteries from overcharging - unlikely with the small panel?

Thanks in advance

 

[VicS]

1. Yes you can wire them directly but put fuses in the +ve connections as close to the batteries as practicable

2. No

3. Not for the small one
but yes for the 12W one
Any thing over 1 watt per 10 Ah or over 10W anyway a controller advisable...... one of the cheap ones that Maplin do will be adequate for your needs PWM regulator is unnecessary IMHO

 

[donm]

1. Yes you can wire them directly but put fuses in the +ve connections as close to the batteries as practicable

2. No

3. Not for the small one
but yes for the 12W on
Any thing over 1 watt per 10 Ah or over 10W anyway a controller advisable...... one of the cheap ones that maplin d will be adequate for your nneds PWM regulator is unnecessary IMHO

Brilliant - thanks very much

In respect of 2, there are warnings on both sets of instructions that the panels should be disconnected before starting?

 

[VicS]

Brilliant - thanks very much

In respect of 2, there are warnings on both sets of instructions that the panels should be disconnected before starting?

That's not something I have come across ... plenty of boats have solar panels connected permanently including to the starter battery.

Perhaps someone else will have some comment to make

 

[fishermantwo]

My mate who is an electronics expert studied the manual for this unit and has got back to me. The battery terminals will charge the battery till 13.5 volts then cut off. The load terminals will supply current till the battery level is down to 10.5 volts then cut off. In my case where the unit is just being used to float the batteries I can just leave the load terminals empty. He was impressed with the units, pretty impressive item for $12.

 

[VicS]

My mate who is an electronics expert studied the manual for this unit and has got back to me. The battery terminals will charge the battery till 13.5 volts then cut off. The load terminals will supply current till the battery level is down to 10.5 volts then cut off. In my case where the unit is just being used to float the batteries I can just leave the load terminals empty. He was impressed with the units, pretty impressive item for $12.

Not quite what I am reading for its spec.

I am reading that it will charge until the volts reaches 14.4. You'd expect this sort of fugure ... 13.5 is too low to be an effective charge

That it will cut back in if the volts falls below 12.6. You'd expect this sort of figure because a fully charged battery resting with no load will maintain this sort of voltage

It will cut off the load if the volts fall below 11V

 

[nigelmercier]

... one of the cheap ones that Maplin do will be adequate for your needs PWM regulator is unnecessary IMHO

I thought that the cheap ones were PWM, the more expensive ones being MPPT. But I agree that a cheap one will suffice.

 

[VicS]

I thought that the cheap ones were PWM, the more expensive ones being MPPT. But I agree that a cheap one will suffice.

The cheap ones just disconnect the panel when volts reaches the max ( 14.4 ??) and reconnect it when it falls to the minimum (12.6 ??)
( Maplins usually have the Kemo ones)

The expensive ones are PWM

The very expensive ones are MPPT

 

[DavidGrieves]

Hi

Sorry for the thread hijack... but on same subject...

I just bought one of these

http://www.ebay.co.uk/itm/Solar-Cha...50544927738?pt=UK_Gadgets&hash=item230d2d4bfa

It is PWM. They are used for battery charging and street lighting controllers. You can set the length of time you want the load to come on for once the solar panel stops being exposed to light. ie.. on for 1 hr after sundown up to 15 hrs or on constant. Have not done it yet but thought it would be useful as an auto anchor light switch. Any thoughts?

Fitted to a 30watt panel and 220Ahr battery

 

[contessaman]

The cheap ones just disconnect the panel when volts reaches the max ( 14.4 ??) and reconnect it when it falls to the minimum (12.6 ??)
( Maplins usually have the Kemo ones)

The expensive ones are PWM

The very expensive ones are MPPT

I bought the maplin kemo dual battery bank one in the end. about to fit it shortly. Somebody touched on the engine driven alternator damaging the solar panels, which I dont think likely (diode), however, what happens to the charge controller when the batteries are well up into the 14 volt range under alternator charging conditions? I assume everybody just hard wires the charge controller and solar panel in and doesnt build in a switch to isolate the whole affair when the engine is running? is that right? can the controllers cope with this?

ta

 

[VicMallows]

I just bought one of these

http://www.ebay.co.uk/itm/Solar-Cha...50544927738?pt=UK_Gadgets&hash=item230d2d4bfa

IHave not done it yet but thought it would be useful as an auto anchor light switch. Any thoughts?

I have one of those, and yes, the lighting output works fine for an automatic anchor light (once you've made some sense of the instructions by experimentation!).

The only problem I have with the controller is that it cuts the charge voltage back to 13.6v less than an hour after the voltage has reached 14.4v. This is fine when boat is unattended and only a maintenance charge is needed, but is hopeless if you want to recharge the batteries with all available solar panel after a discharge.

I overcome this by overriding the controller until my AHr counter tells me the batteries should be fully replenished. On this particular controller you can override it simply by shorting the in/out NEGATIVE connections. I have had no trouble leaving it in circuit together with the alternator on charge.

Vic

 

[fishermantwo]

Not quite what I am reading for its spec.

I am reading that it will charge until the volts reaches 14.4. You'd expect this sort of fugure ... 13.5 is too low to be an effective charge

That it will cut back in if the volts falls below 12.6. You'd expect this sort of figure because a fully charged battery resting with no load will maintain this sort of voltage

It will cut off the load if the volts fall below 11V

Your right Vic. I miss quoted my mate. Top value for $12 still.

 

[stevensuf]

If you are connecting solar panels direct to a battery with no controller, make certain they have diodes in them or they can drain the batteries at night.