Solar Panel output while under winter cover

[Nickc]

I have my 2019 Ranger Tug 23 under a custom made breathable winter cover on land, in Ct. I just went to boat with idea of marking out footprint of solar panel, with the intention of having a clear plastic window stitched in over the solar panel when I take the cover off.
I was kind of surprised to read 15.9V (7.9A) on the solar monitor with the solar panel completely covered by the breathable winter cover, in middle of day under full sunlight. I believe I get 21.8V while uncovered in summer at mid day. It should be noted that the boat is plugged into boats house power outlet (via extension cord and adapter)- but only on a once/week basis and was not plugged in at time I recorded the 15.9V on the solar monitor. Also all 3 battery banks (2house+1Engine+1Thruster) was measured by voltmeter and found to between 12.0-12.2V.
I was wondering - based on the solar panel output while under cover -- if it is worth sewing in a clear plastic window in the winter cover or leave it as is? Any comments appreciated.

 

[Martin610]

I have my Cutwater shrink wrapped. I get good output from the panel all winter. Seems to work like a trickle charger.

 

[Osprey]

If your batteries measure 12.0 to 12.2 while not under significant load they are seriously discharged.

 

[scross]

Second what Osprey said.
12.0 to 12.2 volts not under load is only 25% of charge. That low is probably killing your batteries assuming they are AGM or flooded. Firefly batteries can go almost this low without significant damage.

 

[Nickc]

The (2house + 1Thruster) are 12V Centennial Marine Deep Cycle Group27 Flooded Lead /acid Maint. free + 1 12V CM 800CCA Engine starting Battery Gp27 Flooded Lead /acid.
They were measured @ 12.0-12.2v with my hand held voltmeter at each of the 4 battery +/- terminals while not under load and not hooked up to my charger via boat yard 120v ac power. Both Osprey and Scross advise that batteries seem to be seriously undercharged..
What should the batteries be reading?..if assuming yard is plugging in to my charger once a week.
Should I tell yard to plug in 24/7 to keep up charge on batteries @ proper level. Also if the yard power is plugged in my boats charger -what is the voltage I should be reading?

 

[scross]

A fully charged battery should read at 12.7 volts. On a charger they can go a bit higher.
Here’s the percentage of charge table. You don’t want to go below 12.4 volts to keep your battery healthy.
As they say, batteries don’t die - they are murdered!

Percentage of Charge. 12 Volt Battery Voltage

100. 12.70
95. 12.64
90. 12.58
85. 12.52
80. 12.46
75. 12.40
*********************
70. 12.36
65. 12.32
60. 12.28
55. 12.24
50. 12.20
45. 12.16
40. 12.12
35. 12.08
30. 12.04
25. 12.00
20. 11.98
15. 11.96
10. 11.94
5. 11.92
Discharged. 11.90

PS: Hard to know what the load is in your boat with all the main DC switches off. Even with the DC switches off there’s a lot that’s “always on” like bilge pumps, CO monitor, radio memory, etc. Our solar panel (180 watts) can normally keep up with the always on even on cloudy days. But off season it’s plugged in the shore power (battery charger on) while parked in the driveway and solar on. I run 4 heaters off A/C as well.

 

[Nickc]

Thanks.. for info .... will call yard to plug in boats charger 24/7

 

[rpmerrill]

A couple questions....
This custom cover on your boat: Is it opaque or translucent? Dark or light color?
The 15+volts and 7.9 amps: What is the solar hooked up to? Where are those amps flowing to/thru?.
Same question on the 21+volt claim in the summer.
Do you have a DC clamp on ammeter? That should help you find where that current is going. (Or if it is true.)

We may have a different brand solar controller, but I can't imagine how the voltage output could get that high AND provide amperage at that high a voltage level. If those amps are going to one (or all of the batteries thru the ACRs) and the batteries are only sitting at 12.0 to 12.2 volts, there is something really wrong. That amount of power has to be going somewhere. Are the batteries hot to the touch?

My boat with shrinkwrap still has some solar output all winter. On sunny days it will provide up to half an amp at high 12v numbers keeping the batteries happy. And during visits I often find the ACRs have connected meaning that the voltage on the primary battery got up to at least 13 volts. (It is difficult to determine where the solar wires lead, but based on my measurements it is the house bank first.) Once the house bank voltage climbs to 13 volts, the ACRs connect in a daisy chain fashion sending amperage downstream to the engine first and the thruster batteries second. Once the solar output drops to below 12.75 volts the ACRs disconnect.

 

[Martin610]

All winter my batteries read about 12.9. The Sunsaver Duo lets me do a 50/50 split to both banks. Just so happened I took the cover off yesterday. I'm now over 13, which I think indicates the batteries are in float. Hurrah for solar!

These volt meters may not be calibrated exactly. That's fine, its the relative changes I look for.

When I splash the boat I'll put the Sunsaver back to 90/10.

 

[Nickc]

rj merri/scross.. Tks for your response..My custom cover is light green translucent breathable canvas-like cover. I just realized that the readings I took with my digital voltmeter were at the individual battery terminals with 24/7 loads and solar charger connected- so may not be true state of batteries. The voltages/amps for the solar panels I noted, were taken from the solar monitor. The next time I am down there will check if batteries are hot to touch (although I doubt it).. I think rather than start connecting and reconnecting loads etc...I am going to ask yard to take cover off as soon as they can to get full solar benefit and put charger on full time. Boat is splashing end April

 

[knotflying]

Quite frankly I think you would be better off just disconnecting the negative wires on the batteries and not worry about any drain on them. If you have power nearby a trickle charger will work and you can do that. The best, and in my opinion good perioding maintenance. Disconnect all wires, zip tie together and label them and remove the batteries and bring them in your shop and you can test the voltage monthly to see if they drop. Usually a good battery will lose little. In the spring clean out battery compartment. Make sure your hold down straps are in good shape and screws are holding battery rack down. Clean up all wire connections and battery terminals and reinstall. It sounds like a lot of work, but it is good maintenance practice.

 

[Kevin Lamont]

I have my 2019 Ranger Tug 23 under a custom made breathable winter cover on land, in Ct. I just went to boat with idea of marking out footprint of solar panel, with the intention of having a clear plastic window stitched in over the solar panel when I take the cover off.
I was kind of surprised to read 15.9V (7.9A) on the solar monitor with the solar panel completely covered by the breathable winter cover, in middle of day under full sunlight. I believe I get 21.8V while uncovered in summer at mid day. It should be noted that the boat is plugged into boats house power outlet (via extension cord and adapter)- but only on a once/week basis and was not plugged in at time I recorded the 15.9V on the solar monitor. Also all 3 battery banks (2house+1Engine+1Thruster) was measured by voltmeter and found to between 12.0-12.2V.
I was wondering - based on the solar panel output while under cover -- if it is worth sewing in a clear plastic window in the winter cover or leave it as is? Any comments appreciated.

Hello,

The above response is best for when in storage while under a cover. It is a bit of work to do but more of a worry free way of keeping batteries good when without shore power to keep charger on. Also I would be interested when you saw 15.9v if you were looking at the MAX voltage that was recorded. The solar controller panel records MAX and MIN voltage FYI. Hope this helps.

Thanks,

 

[Nickc]

Update-- It appears as someone indicated above --I was not checking checking the battery voltage correctly while under winter cover (with some solar charging thru translucent cover and weekly charging while on the hard).
All my Centennial Marine batteries (2house+1thruster+ 1engine ) have have 2 terminals for each +/_ .. One with post and another wingnuts. The low 12.0-12.2 readings I previously got was taken on the wingnut terminals.
Yesterday Under same conditions ( no yard charge plugged under translucent cover in at time I took reading) -- I got all 13.3-13.4v readings on all batteries-- this time readings were on on the bare battery posts (not wingnut terminals). I guess readings off bare posts are the ones that matter-- the wingnut terminals are connected to 24/7 loads and are therefore lower. Looks like my batteries are being adequately charged while on the hard---

 

[dgiles]

Update-- It appears as someone indicated above --I was not checking checking the battery voltage correctly while under winter cover (with some solar charging thru translucent cover and weekly charging while on the hard).
All my Centennial Marine batteries (2house+1thruster+ 1engine ) have have 2 terminals for each +/_ .. One with post and another wingnuts. The low 12.0-12.2 readings I previously got was taken on the wingnut terminals.
Yesterday Under same conditions ( no yard charge plugged under translucent cover in at time I took reading) -- I got all 13.3-13.4v readings on all batteries-- this time readings were on on the bare battery posts (not wingnut terminals). I guess readings off bare posts are the ones that matter-- the wingnut terminals are connected to 24/7 loads and are therefore lower. Looks like my batteries are being adequately charged while on the hard---

That is interesting because the wingnut and the bare terminals should be connected to each other. If so, it is impossible to have a voltage variance across them.