Solar failed me

B

Boatagain

Well-known member
Joined
Sep 13, 2014
Messages
252
Fluid Motion Model
C-24 C
Non-Fluid Motion Model
Cutwater 30
Vessel Name
Gatsby
Hi Everyone,

Family and work issues kept me away from our ‘16 C30 for over two months. Finally had a chance to get down to the marina today. The shore power breaker had tripped - something that happens from time to time - so no battery charger. For how long, I don’t know. Went to start the engine and got the pitiful click indicating a dead battery. Went to turn the parallel battery switch and discovered that it was already on. My bad. Still no engine start.

The DC voltage monitor on the breaker panel, at first, showed very low voltage but as soon as I reset the shore power breaker, the voltage climbed right up into the 13 volt range within seconds.

Shouldn’t the solar have kept the batteries charged? Did the parallel switch being left on cause this? Did I ruin the AGM batteries because my stupidity let the voltage get too low?

Any help appreciated.
 
Need a bit more info.

Did you have anything on the boat left on? Such as the fridge or inverter?

The parallel switch def contributed to the issue since the ACR's normally would have cut out stopping the engine battery from draining.

If this is the first time the batteries have gone flat then you probably decreased some of their capacity, but it also depends how long they were flat and allowed to sulfate.
 
Might not be the same cause, but when my boat arrived at the dealership, I noticed that the house batteries showed lower voltage than the other two banks. After snooping around, I discovered that somebody had left the inverter turned on, and it was humming away consuming 12 volt electrons to make unneeded 110V electrons. After turning it off and giving the solar panel a chance to recover for a day, the house bank came up to the same level as the other two banks. You might want to be sure your inverter is turned off. And of course, turn off all the battery switches unless you need them for something.
 
Solar won't keep up with the fridge if that was on.
 
Hi,

Aside from the refrigerator being powered on, you also have your CO monitors and bilge pumps cycling constantly. Depending on how sunny it has been, the solar panel may not have been able to keep up. Since you had the parallel switch on, you also had a draw from the engine bank for the LPG controller, seat sensor, volt meter, and the hatch switch. If you have the outboard version, it also has a draw for the engine pod bilge pump.
 
Martin610":y1mpfdsx said:
Solar won't keep up with the fridge if that was on.
Click to expand...

My solar doesn't fail me, and it will power the refrigerator indefinitely if there is a little sun every day. The first thing to look for is shadows. Even a tiny shadow as small as one square inch can reduce the solar power available. A shadow the size of a radar can block about half of the solar panel's output. The watt-hours out of the solar panel must exceed the watt-hours drawn from the batteries.

The factory-supplied solar systems tend to be a single panel with a PWM controller. They can work well on a sunny day with no shadows, but they produce nothing on a cloudy day. I installed two solar panels with an MPPT controller. The MPPT controller optimizes the amount of power transferred from the panels to the batteries even if the solar panel puts out much less 12 volts. Typical solar panels put out about 19 volts and the PWM controller throws away all of the voltage above the battery voltage, resulting in much less power to the batteries. The MTTP controller acts as an inverter and translates a wide range of input voltages into the ideal charging voltage for the batteries.

I have two panels in series, putting out about 38 volts on a sunny day. The MPPT controller converts almost all of the solar generated power into battery-charging power. On a very cloudy and rainy day, my series-connected solar panels still put out 10-15 volts, so the batteries continue to charge even on bad-weather days.

Why don't all systems use MPPT controllers? They are expensive.

Marshall
 
To be honest an appropriately sized MPPT from victron is really not that expensive any more.

https://www.amazon.com/dp/B01D7RI7LG/ref=psdc_2236627011_t2_B075NPQHQK?th=1

the morningstar MPPT is not expensive either.
https://www.amazon.com/MORNINGSTAR-...t&qid=1573237627&s=electronics&sr=1-1-catcorr
i would choose the victron (good product, bluetooth monitoring): it just takes more space than the sunsaver.

it should be noted that even the smallest shadow on the panel that is isntalled on our boats will drop the charging amps to almost zero.
you have to keep the shadows off the panel.

with the radar tower as it is, I think the best solution on our boat is two seperate panels on an MPPT controller that way if one panel is in shadow the other will still be charging. this is better than a single larger panel. (as long its wired correctly)
my understanding is, wired in series if one panel is in shadow then both are effected even with an MPPT controller. Wired in parallel they operate independantly but... the amps running to the controller is much higher and will need thicker wiring... not great for us as we have to rerun wires up through the roof.
 
 
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