Solar charge controller y/n?

[KevinV]

Found a 60w panel that will fit on my hatch, so the next question is whether I should use a controller. Battery is only 85Ah, but solar on a curved surface is going to be pretty limited anyway. The only other charging source is 5A from the outboard.
There'll be plenty of time between weekend sails - would it be a good idea to add another battery? There's space for one, the boat obviously had two before, but I'd rather use one well than ruin two by undercharging.
Normal instruments, led lighting, a tablet and a tiller pilot - that's it.

 

[VicS]

Rule of thumb is that if the solar panel rated output is more than 1 watt per 10Ah of battery capacity , or is more that 10 watts fit a controller

Yours exceeds both those limits by a mile so absolutely fit one. A PWM one will be adequate.

 

[William_H]

Yes fit one. The controller in it's simplest form will conduct solar panel current direct to the battery until such time as battery is charged when it will stop the current. At 5 amps from your panel in full sun that could cook your battery. Fit another battery? That would depend on if you need more reserve power. Another battery is more outlay to buy and another battery slowly dying of old age. Plus more weight. ol'will

 

[KevinV]

Thanks for the clear answers chaps, pwm it is.
I guess I will see how I get on with the current battery - the big unknown to me being how much power the tiller pilot uses in real life.

 

[VicS]

Thanks for the clear answers chaps, pwm it is.
I guess I will see how I get on with the current battery - the big unknown to me being how much power the tiller pilot uses in real life.

I have a tiller pilot, a very early Nautech Autohelm. Usually being single handed the Autohelm is in use a good proportion of the time, Until recently all the lights were filament bulbs or fluorescents. I have never felt the need to take the tablet sailing

I have a 60Ah battery charged minimally from the outboard and a 5 watt solar panel. I find the 5 watt panel recharges the battery between week end sails.

 

[andsarkit]

I had a 30W panel mounted horizontally charging 200Ah of batteries with no controller. This was fine and I never saw more than 13.7V on the batteries and they usually sat at about 13.5V. This should be fine for a float charge. I fitted a voltmeter like this Lascar to monitor the voltage (easy to fit with just 2 wires and a small hole). I will soon fit 2 x 30W panels and an MPPT controller as there is a possibility that this might overcharge the batteries in summer.
Autopilot consumption will vary with sea state and boat balance but I would guess an average of about 1-2A. Years ago I ran an original Nautech Autohelm continuously from a 75Ah battery with a small 0.5A wind generator. I only needed to run the engine about every 5 days.

 

[Stemar]

One of these would be more than enough, at change from £20,

EP Solar Landstar 10A 12V Solar Charge Controller 120w

You could get away with the 5 amp version, but 60W at 12v is 5 amps and you'd only save a fiver. Rightly or wrongly, I'm a great believer in not pushing electronics to their limit.

By all means add more battery capacity, which would make the tiller pilot consumption less of a worry. The 40W I had on my last boat kept nearly 200AH of batteries topped up nicely, even in winter.

 

[Alfie168]

For what a basic charge controller costs just fit one. It's peace of mind.