Shrink wrap over a solar panel

[jen1722terry]

Hi CDers!

Question: will our 130 watt solar panel still charge if it covered with shrink wrap?

Why do we need to know this? Well, we just hauled the boat and it is on the hard with trees shading the solar panel. This means it may be hard to get the 3 AGM batteries (2 years old) topped up before we disconnect them for the winter. So, can we leave the batteries connected, with the battery switch off and the elec. bilge pump disconnected and shrink wrap over the solar panel? The shade tree are hardwoods and will be bare soon.

Or will the shrink wrap disable the panel or make it charge so slowly that it will not top up the batteries?

All advice deeply appreciated.

And for those of you still sailing in New England, enjoy this beautiful weather.

Cheers!

Jenn and Terry

[Jim Walsh]

My solar vent operates all winter under my canvas cover whenever the sun is shining so I would presume my solar panel (new to me this season) will also operate all winter in favorable conditions. I presume, we all know what happens when we presume, it will lose efficiency but as long as it generates a few amps it will keep my flooded batteries topped up during the off season.

[Paul D.]

Jenn & Terry,

If your solar panel runs through a charge controller then it should be fine to leave hooked up to your batteries over winter. A white shrink film over the panel will drop the output of the panel significantly but I would think it would still trickle charge at least. Check your battery manual to be sure and find out what % charge of your battery capacity you can safely have going into them without overcharging. I am not familiar with AGM specifics.

We have a 60w panel run through a Ferris charge controller on Femme that provides 2.5 amp hours in full sun to our house bank. Over winter I shrink the boat myself running the shrink film under the panel. I usually tilt the panel (on the stern rail) away from the sun to drain rain and snow. I top off the 6 volt golf car batteries and leave it for the winter.

[jen1722terry]

Thanks so much to Jim and Paul, always sources of very sage advice.

We actually called the battery maker, Odessy, who said a top up and disconnect was fine, even in Maine. They also said our solar controller, SunSaver, would be fine also if we were unable to get a good top-up.

However, we were quite pleased to see enough morning sun today to run up all three batteries, so we opted to disconnect. It worked fine last year, and we'll try it again. Problem was, we also had to turn off the fridge, so no cold beer tomorrow.

We also have solar vents for our engine room, and they do hum away under the shrink wrap.

Speaking of shrink wrap, in the spring of '16, we really needed it to do the decks in Perfection and Kiwi Grip. The weather in Nova Scotia was horrible all of May, so we donned good respirators and did the laborious job "under wraps." Can't recommend the technique, and we hope to never do it again. The Perfection is holding up fine, even on the foredeck with the anchor chain dragging over it. The Kiwi Grip has a few nicks, but it only takes a few minutes to touch it up.

Gees, the weather here in Blue Hill, ME, has been glorious with some moderate breezes. Pity we had to haul a bit early.

Thanks again,

Jenn and Terry

[Maine Sail]

We actually called the battery maker, Odyssey, who said a top up and disconnect was fine, even in Maine.

Please listen to them!!! Beg, borrow or steal a small generator or get a long extension cord and portable charger if you have to, and top them up at 14.7V for no less than about 4 hours. If they have been chronically under charged charge them at 14.7V for closer to 8 hours. By spring, if 100% disconnected, your Odyssey batteries will still be hoovering around 12.9V to 13.0V, if you got them full in the fall. At 77F these batteries are designed to be stored for at least two years but at 40F they can be stored as long as 4 + years. The colder it is, the less self discharge there is. A winter in Maine is a drop in the bucket for an Odyssey battery.

By 100% disconnecting/isolating the batteries from;

The vessel
Each other
Charging sources

You have basically zero risk.

By leaving them connected to ANY of the above, you create the potential to have a huge hole where your wallet used to be come spring.

They also said our solar controller, SunSaver, would be fine also if we were unable to get a good top-up.

#1 The Sun Saver (no idea if it's MPPT or PWM version) is not the best choice for your very expensive Odyssey batteries, if you want the life expectancy you paid for.. Odyssey batteries do best in a PSOC environment, (sailboats are partial state of charge application) when they are charged with a temp compensated absorption voltage of 14.7V.

Neither of the SunSaver products can do this. Even if you choose the flooded profile the most you're getting is usually 14.4V and on the PWM unit it will then auto equalize ever 30 days, also not good for Odyssey batteries. If you choose sealed then it will charge at about 14.1V which is even worse for Odyssey batteries. Morningstar controllers are EXCELLENT & very reliable. However with Odyssey or Northstar or other expensive batteries they are only excellent when you get into the models that allow full custom programming. In the Morningstar line up this means ProStar and up. The ones that don't offer custom charge profiles are still very reliable but far less than optimal for your batteries.. Perhaps the best value today in solar controllers for small arrays are the small Victron controllers. These allow full customization of charge profiles including equalization, absorption duration, float voltage, absorption voltage & even temp compensation slope.

#2 Covering your panels means that the controller is still connected to the bank and it will always have some parasitic load/draw. While this draw is quite low, about 0.04A, I have seen numerous instances of winter time solar both over charge batteries, usually caused by temp compensation & full batteries, as well as kill them when no solar is available due to snow load.

#3Automatic temp compensation is fine during the in-use cycling season but in winter compensating up as high as 15V, because ambient air/battery is cold, means your batteries, which should already be 100% full and accepting near zero current, are getting a super high 15.0V every day the panel can produce even small currents. With 100% full Odyssey batteries, that have near zero self-discharge at these temps, 15.0V could happen far too often. Not a good practice for expensive batteries.

#4 If you must leave solar connected to the batteries, then a controller that allows you to program temp compensation to OFF, equalization to OFF and Absorption and Float to a permanent float level eg: Absorption to 13.5V and float to 13.4V is the only way I would even consider it with expensive AGM batteries. These batteries are specifically designed to not need continual charging over the winter. heck they can survive for two or three winters back to back and still not need a charge.

However, we were quite pleased to see enough morning sun today to run up all three batteries, so we opted to disconnect. It worked fine last year, and we'll try it again.

You ran the batteries up as high as the controller will allow but it is still far too low. Each fall you should try to get them to at least 14.6V to 14.7V for 4+ hours. During the season they should also regularly be charged to 14.7V or they will suffer a considerably shorter life. EnerSys (parent company of Odyssey) has done extensive testing on these batteries and the effect of absorption charge voltages on cycle-life.

The difference between charging an Odyssey at 14.2V and 14.7V is a massive difference in cycle life. In one EnerSys test the batteries that were charged to 14.2V barely made 100 100% SOC to 0% SOC cycles where as the batteries charged to 14.7V exceeded 400 100% SOC to 0% SOC cycles. When you translate this up to 80% DOD cycling or 50% DOD cycling the spread between 14.2V charging and 14.7V charging grows even wider.

Treat your premium Odyssey batteries well and they will treat you well.

[Megunticook]

Hey, didn't know Main Sail was in the house. I've learned a whole lot from your stuff online.

Quick question about the MorningStar products: I saw on your site that you recommended the ProStar, but I ended up getting a SunSaver PWM because the ProStar manual says it should not be exposed to moisture. My installation is in the cabin, but I figured in the marine environment it would be exposed to very high humidity and possibly get a bit of rain or spray. I take it you haven't had any issues?

I just have one 80 amp-hour Exide deep cycle marine battery that came with the boat, and I keep a close eye on it, so I'm not too worried. The battery is 5 years old now, a thinking of replacing with a Trojan flooded battery next year. You like those? The battery just runs VHF, nav instruments, and lights, so pretty light loads.

One other question regarding wintertime--I generally remove it from the boat and store it in my tool shed at home October through April, and use a Battery Tender once a month or so to top it off. But I'm not sure I should trust that Battery Tender fully (you get what you pay for, right?) Can you recommend a good reliable plug-in bench charger that allows you to program the voltages?

And what do you think about having the stored battery on a constant float charge during the winter (checking on it regularly, of course)?

Thanks for your expertise.

I have a mooring question for you also but will start another thread for that.

[jen1722terry]

Hello again, and sorry for the delayed response on this thread. Very busy with haul out and travel to our winter home in Canada.

Thanks so much to Maine Sail for taking the time to comment in detail on this important thread - important, at least, to those who have expensive AGM batteries.

I talked with the Northeastern rep for Odyssey batteries today. He noted that one cannot charge the batteries we have up to 14.7 volts. just over 13 volts is fully charged. However, he also said that one should have a charger that can provide up to at least 14.7-plus volts to get the 13-plus volts in the batteries.

He referred me to the following text from the Odessy manual:

"WINTER STORAGE
ODYSSEY does not lose its charged energy during cold storage temperatures, so there is no need to trickle or float charge during winter months. To store off-season, measure the battery voltage to make sure it is fully charged, 12.84 volts or greater; recharge if necessary. Disconnect the negative battery cable to prevent any applied electrical load during storage. ODYSSEY cannot freeze down to -40°C or -40°F so it can be left in the vehicle. It can be stored for 2 years or more below 77°F.
A 12V, 3 amp trickle charger can also be left connected to the battery if it is kept in storage for extended periods or if the battery is subject to parasitic loads during storage. Information on two such chargers we recommend, including where to buy them, can be found on our website at www.odysseyfactory.com/odycharg_c.htm.

Our three batteries all measured just over 13 volts when we disconnected and tied off the black ground cables from each battery. This charge was delivered solely by our 130-watt solar panel and our Sunsaver solar controller.

But our concern is: an experienced and respected mechanic, known for being very concerned about the safety of his fellow boaters, thinks that we should put a charger on our batteries before winter sets in. We will, to cover all our bases.

We also note that the Odyssey rep felt that no solar panels should be relied on for prior-to-winter-storage charging, which puzzles me. We have two different battery charge meters (one for each individual battery and one that monitors the two house bank batteries together, and the one starter battery). All the meters measured just over 13 volts when we disconnected the batteries for the winter last week.

Fortunately, for us, all three batteries measured just under 13 volts the last two springs ( last spring the boat had just come out of heated winter storage), so we hope we have not damaged this expensive investment. If they were damaged, chalk it up to our ignorance and some bad advice from a respected Nova Scotia marine electrician, but it appears that the batteries will be fine.

If any of you have more thoughts on batteries and charging, please let us know. We live on-board for 3 straight months each year and use our batteries more than most of you, but not nearly as much as the full-time live-aboards. We opted for the expensive ($1800 Canadian including tax for three batteries) Odyssey batteries for low maintenance (two or our batteries are under the cockpit and hard for 68-year-old me to get to) and hoped-for longevity.

And, again, thanks to Maine Sail for his sage and in-depth advice. You're an asset to all sailors.

Jenn and Terry

[tjr818]

Jennifer & Terry, Thanks for all of that information. I have switched to Odyssey batteries for the exact sam reason, although they are much cheaper her in the midwest U.S.A. I tried your link and could not get it to work. Could you post a corrected link please?

[jen1722terry]

Hi Tim,

Not sure why the Odyssey link doesn't work. It was pasted in from their website. Their email link on their site did not work either. Try googling Odyssey.

Question: are you using a solar panel and solar controller also? If so, what brand and model controller. I may have the wrong one, but I plan to call Morningstar to check next week.

Cheers!

Terry

[jen1722terry]

For those of you who commented on our confusion about charging and winter storage for our Odyssey AGM batteries, many thanks.

After a few calls to two different tech support people at Odyssey to cure the undercharging of our three AGM batteries before winter storage, we learned the following:

The current charge of 12.6 volts in each battery is way too low for storage and could indicate some sulfate buildup in all three batteries.

The Odyssey 20 amp charger (about $200) is pre-programmed to bring the batteries up to a full charge of 12.84 volts, though it may take longer than a higher capacity charger (about 24 hours). This is all that is needed for winter storage outdoors in Maine.

In the spring, we should run through the recondition program on the charger to remove sulfates and restore the batteries.

The Morningstar Sunsaver solar controller is not adequate to keep our batteries charged up. We have to switch to a larger, programmable model. We will do this in the spring.

If any of you still have questions about your Odyssey AGM batteries, the Odyssey website has technical manuals that can be downloaded, or you can call their very helpful tech people.

Thanks again for all your help.

Jenn and Terry

[jen1722terry]

Hello again,

I’d like to resurrect this thread to update all of you on our continued issues with charging our Odyssey AGM batteries on our CD 31.

We have two Odyssey group 31s (92 ah each) for a house bank and one Odyssey group 24 (62 ah) for a starter (all installed new in 2015). We also have a 130 watt solar panel and a new 65 amp engine alternator. We originally had a Morningstar Duo-Saver solar controller charging the house bank and the starter battery on separate circuits controlled by the standard battery selector switch.

On the advice of some kind folks on this board, especially Maine Sail, we learned that the Duo-Saver was not providing sufficient voltage to fully charge and maintain the three AGM batteries. So, we recently had a local solar electrician here in coastal Maine install a new Morningstar ProStar MPPT 25M controller.

A couple of problems occurred with the new controller installation:

The electrician informed us that we no longer have a separate charging circuit for our starter battery. All three batteries are now on one circuit. Thus, if a malfunction (like a bilge pump switch) should run down the batteries, we have no separate starter battery to rely on.

2. We just heard from Odyssey that, even with the new solar controller, we do not have sufficient solar charging power on board to get the full absorption charge on all three batteries. Thus, we may be slowly killing the batteries by not bringing them up to the full float charge at fairly frequent intervals. Sulfation of the batteries will eventually kill them.

3. Also, we’re not sure how long we have to run the engine and at what speed to have a chance of getting the two 92 amp AGM batteries to a full charge on a sunny day or on a cloudy day.

So, we feel we may have gained little by spending $800 to have the Morningstar ProStar controller installed.

So, what to do?

1. We own an Odyssey portable charger. We can bring the boat into a slip for shore power once a month or so and run the full “recondition” program on each battery individually to remove sulfation.

2. Disconnect the 62 ah starter battery completely (remove ground cable from battery) from the charging circuit (after reconditioning). It will just sit on board disconnected for the rare time we may need an emergency starter battery: it would then be used to start the engine with jumper cables or, if possible, by reconnecting it to the other two batteries via the solar controller for the engine start (this may not work if the other two batteries are really under charged). We’re not sure how to start our engine with jumper cables only now that the batteries are all on the same charging circuit (“in parallel” according to the Morningstar rep).


3. Doing the above would leave us with two, 92 ah Odyssey AGM batteries on the one solar charging circuit. We’re not sure that, even with this lower total amperage, we can fully charge these two batteries using our Prostar MPPT 25M controller with or without our 65amp engine alternator. We’re also not sure how long it might take to fully charge the batteries with the solar and engine alternator.

Any advice any of you can give would be most appreciated. If worse comes to worse and we’re slow killing our AGM batteries, we can start planning for new batteries that will work better with our on-board charging capabilities.

Pasted in below is the most recent message from Odyssey technical support.

Any comments or advice any of you can offer would be deeply appreciated. Also, if any of you can recommend a good marine electrician in the Mt. Desert Island area, we would love to hear.

Now, today, we’re looking forward to seeing many of the CD Maine summer cruise gang today at cocktail hour in Northeast Harbor.

Jenn and Terry McAdams
CD 31 “Glissade”

From Odyssey Battery customer support:

Equalization (exceeding 15.0V at 77°F or 25°C) is not recommended for any ODYSSEY battery as it can lead to overheating due to overcharging resulting in loss of critical moisture and premature failure. The charger is temperature compensated and that is good. You may see voltages exceed 15.0V when the temperature drops below a certain point which is acceptable when required. When paralleling batteries, the battery bank becomes the total Ah rating of all of the batteries in the bank. In this case 92 + 92 + 62 = 246Ah at the 10 hour Ah rate. At 40% of that rating, we would recommend a minimum charge current for the entire bank of about 100A. I would suggest doing a custom setting with Absorption at 14.7V for 180 min or longer if available, Float at 13.5V, and Equalize OFF. If the equalize mode can be set at 14.7V as well, then I would suggest turning that ON with maximum length available as well to prolong the Absorption time on charge if that is how it works (ask Morningstar to verify). That said, if the batteries are at 50% depth of discharge (12.2V with no electrical load), at 125Ah to recover it would take 5 hours (300 min.) at an optimum charge current of 25A at 14.7V to get to a 85-90% state of charge. Hence the recommendation to charge at 14.7V in both Equalize and Absorption modes for a combined charge time of about 420 minutes if that is how it works.
 
Note that a higher current charger would be recommended for the entire bank. At 25A (optimum) the charging system will eventually get the batteries fully charged however, I would not recommend discharging them below 50% depth of discharge on a regular basis. Most solar charging systems are about 85-90% efficient and can be less efficient and are dependent on the sun availability. A 130W solar panel can provide 8.8A at 14.7V optimum. I’m not sure but I believe that even if the controller can work at 25A max, a single 130W solar panel will never provide that type of current. It would take 3 panels that size to max out the system. I would contact Morningstar to confirm. If I am correct, then at optimum of 8.8A (100% efficiency), it would take almost 30 hours constant voltage at max current at 14.7V to get the batteries to 100% state of charge from 0%. Again, low current “trickle” charging is not recommended as it will contribute to the premature sulfation of the batteries over time. Solar charging tends to be that way. It will eventually get the batteries fully charged but will not de-sulfate the batteries as well as with higher current charging (100A for the battery pack).