Solar Trickle Charging Stored Vehicle Batteries During Canadian Winters

Need to store an RV, car, boat, SeaDoo, or ATV for the winter?
Here's a quick look at your solar options for keeping your vehicle battery maintained through our Canadian winter, and avoid the cost of a ruined battery in the spring.

How much power do you need?

A typical flooded lead-acid battery will self-discharge at approx 40% per year. Doing the math, this means that for a typical group 27 or group 31 battery, you will need to offset at least 1 Watt-Hour per day. Sounds easy enough.

But, before you run out and purchase one of those little dashboard solar panels, there are a few things to consider...

1. What sunlight exposure are you likely to get?

2. Are you wanting to charge through a window?

3. Are there any 'mystery loads' on the battery?

4. What solar cell chemistry will be used?

5. Do you need a charge controller?

I'll deal with each of these quickly...

1. Sunlight Exposure

Winter in Canada. Need I say more?

Even if you get a string of sunny days, if you can't get a sunburn, then neither can the solar panel!

Check for obstructions like trees. Shading will drastically cut your solar charger's output.

So, considering only our latitude & weather, solar radiation for most Canadian locations can fall from a summer high of 5-6 peak-sun hours per day to less than 2. In the case of Vancouver, it falls to less than 1 in December!

This means that for most Canadian locales, you will need at least a 2W panel to deliver your desired 1 Watt-Hour Per Day of power (for the smaller group 27 & 31 battery formats).

If you have trees shading your property for part of the day (hopefully not the middle of the day), then double this estimate.

2. Charging Through A Window

Window glass absorbs a lot of UV. So much so, that any solar panel charging through a window will lose as much as 50% of its power output because most of its power is generated from UV light.

So, if you plan to use a dashboard-mounted solar panel, you'd better double your original estimate for power needs. That 2W panel is now up to 4-5 Watts with a window in the way.

3. Mystery Loads?

Clocks, meters, and stand-by control circuits all work to drain your battery power without you noticing. If you can disconnect them all for the winter, great!

If you can't disconnect them all, you'd better make an allowance for the power lost, which can be at least as much as the natural self-discharge rate of the battery.

Poof! We are now up to 8 Watts of solar to keep our single battery maintained.

4. Solar Cell Chemistry

Some solar cells are more sensitive than others. For Canadian latitudes & climate, we will want the most sensitive so that we can collect the most power in any daylight conditions. It just so happens that the most sensitive is NOT crystalline silicone cells like the ones you see on rooftop systems. Crystalline Silicone panels are the most efficient, and therefore produce the most power per square inch "In Direct Sunlight".

The solar cells most recommended for low-light & partial shade conditions are the amorphous silicone or "Thin-Film" solar panels. These have a very flat appearance, and do not have the little rectangular or hexagonal wafers wired together under the glass.

The other advantage of thin film panels is that they can be produced in foldable or rollable format for easy storage, and are very light weight.

5. Is A Charge Controller Needed?

The usual answer is 'YES', however if the panel is only being used for trickle charging, offers less than 1% of the battery's capacity in Amp-Hours, and operates in the 15-16V range under load, then you can safely forgo the charge controller.

That being said, I advise getting one just to be certain your batteries are being cared for during peak sun seasons.

Products To Check Out...

Here are a few solar panels that can help you in keeping your vehicle batteries charged over the winter months...

Powerfilm R7

Powerfilm R14

Powerfilm R21

& a couple of handy traditional crystalline panels designed for all types of vehicles...

SunCharger 5

SunCharger 10

Let me know if you need any help determining how to keep your boat, RV, ATV, SeaDoo, or other vehicle battery maintained over the winter.

Showdown : Thin Film vs Crystalline Solar Panels

As should be expected, I get asked all the time what is the best solar panel to use. There are essentially two types: Thin Film & Crystalline. Each have their own sub groups, like amorphous silicone & CIGS in the thin film realm, and poly crystalline and monocrystalline in the other. But what is the 'best'? The answer is, as it always is... it depends.

I know, that is not very satisfying. So I will look at the technologies from several different perspectives. These are the metrics that people care about most when purchasing a solar charger, and my suggestion would be to choose the three that are most important to you, and choose the technology that satisfies these best.

1. Efficiency
The efficiency title goes to the crystalline solar cells.
Crystalline solar cells are upwards of 20% efficient in commercial-grade cells now, compared to something in the 10% range for the thin films.
However, you need to understand what this means. This does NOT mean that a 5W crystalline panel is more powerful than a 5W thin film. A Watt is a Watt after all, and in peak sun, two 5W panels will each be generating 5W of power regardless of the solar chemistry. A higher efficiency simply means that you will produce more Watts per square meter. The 5W thin film will be approximately twice the size of the 5W crystalline panel.

2. Weight
The weight loss winner is: Thin Film.
Even though the crystalline solar panel is half the size, it weighs more due to the rigid backing needed to protect the crystalline cell wafers & associated wiring. All that aluminum, plastic, resin, & PVC add to the weight of the crystalline solar panels. If only silicon wafers weren't so fragile!
Thin films on the other hand can be laminated or even sprayed onto all sorts of surfaces. The result is solar panels that can be flexible, and add far less weight to your pack.
If you need to carry it, the thin film panels will be nicer to your knees.

3. Sensitivity
It's not psychology, it's chemistry... Thin films are more sensitive
This is a VERY IMPORTANT attribute, and one which should be considered carefully. Sensitivity simply means that the solar cells will start generating power in lower light levels. The practical side of this is that a thin film panel will enjoy a longer charging day than crystalline panels will.
An experiment to illustrate...
I ran a test of several different solar panels one drizzly morning in late May. I had a Powerfilm R-7 rollable, a Brunton SolarFlat 5, Goal Zero Nomad 7, SunLINQ 3, and a Voltaic 3.4W kit. The only panels that were producing enough voltage at 10am on that drizzly, overcast, late spring morning were the thin films (Powerfilm, Brunton, SunLINQ). The crystalline panels were back at 50% of their nominal charging voltage. Crystalline solar cells work best in direct sunlight. Anything else, and thin films are your best option.

4. Durability
I give the championship belt to... thin film.

Voltaic Fuse 10W - Crystalline

This is a difficult parameter to gauge sometimes, because a lot depends on the construction of the product itself. But, when I think about which solar panels could survive being dropped off a cliff, there is no question that being lightweight & flexible has its advantages.
Durability is not to be confused with longevity... the 20-year power output warranty on crystalline panels is not yet matched by the thin films. Crystalline wafers lose their ability to generate power over a much longer time frame.

5. Cost
The winner is you.
What I mean by this is that product differentiation has rendered this parameter almost impossible to gauge. There are so many products for so many applications using so many variations of solar cells, that the only way to consider 'cost' properly is to shortlist products based on the above parameters, and then consider cost last. But, if we look at the cost of a basic framed panels to level the construction materials & manufacturing playing field, then we can see a slight advantage to crystalline panels. Maybe it has something to do with an over-supply of solar cells from China in recent years, but a quick web price search and calculation shows approx $5/Watt for crystalline, and $6/Watt for thin film.

How to choose?

Powerfilm R7 Rollable - Thin Film

I always start with the question: "Where are you going?"
If you are a westcoast Kayaker, or work in the mountains or up north where the weather is relatively unpredictable, you will likely find a more sensitive solar panel (ie thin film) to be your best option. If you do education programs in rural Africa, or development missions to Haiti, where direct sunlight is not a problem, then crystalline panels may be your best value.
Then consider matching the size of the panel to your power needs, deciding on power storage batteries, and the packability of the product, connectivity, etc.

Need any help choosing?
Send me a note!

Solar Advice : Charging Your Camera

I thought it might be handy to provide a quick reference to the essential info you need to know in order to charge any camera. From simple point & shoot models to top-end dSLRs. I promise not to go into great detail like I do on ModernOutpost.com... just the essential info.

First things first... a couple of important FAQs...

"Can I use the charger that came with my camera?"
No. To do so requires additional equipment you won't want to carry, & you will waste a lot of solar power in the process too. For simplicity & efficiency, use a DC charger instead (see info below).

"I already have a solar panel... can I use it?"
Yes. Follow through this article as if you don't already have a panel, and then see my "What If" notes at the end.

"I have some other devices to charge, like my phone & GPS. What do I do?"
No problem. Read through this article assuming just your camera, then see the "What If" notes at the end.

Here we go...


What kind of battery does your camera use?


A : If it uses a little 3.6V or 3.7V battery pack, see the USB Charging sections below
B : If it uses a little 7.2V or 7.4V battery pack, see the 12V Charging sections below
C : If it uses AA batteries, see the NiMh AA Charging sections below

Next, we choose a DC charger to use instead of the AC model that came with your camera...

A : USB Charging
You'll be happy to know that this is the simplest, and least expensive of all the solar charging options.
Here is the charger you will want...
        Lenmar Universal USB Clip Charger
Why? It adapts to virtually any small 3.6/3.7V battery, holds it securely, uses very little power for its own functions. Simple is beautiful. Is it safe? Yes... all the smarts are in the battery packs these days anyway, so the charger doesn't need to do much.
Got a camera that can charge directly in the camera via the sync cable? Great, give it a try to make sure it works from solar... the camera might consume some power itself to do the job, but it saves you the cost of buying an additional charger.

B : 12V Charging
You have a larger battery pack for a dSLR, camcorder, or premium point-&-shoot. No problem. Here's are the chargers I most commonly recommend...
        Ansmann Vario
        Ansmann Vario Pro
        Generic 3-Way
Why one of these? They adapt to your battery, and any other camera battery you might ever own, & can power from wall socket, car, or solar panel. The 3-Way can also power from USB, but it is slow.
Want to save a few bucks? You can use one of the generic AC/DC chargers designed for your particular camera battery model. See them here.

C : NiMh AA Charging
Definitely the cheapest type of camera battery around, but you probably find that you need to charge more frequently. Use the following charger...
        PowerEx C401
Why? Your camera might use 2 AA batteries, it might use 3, it might use 4. Regardless, you will want to charge each battery individually, so you will want a charger that has single channels (ie not just 2 or 4 batteries at a time). Also, this charger doesn't use much power for itself, and it is happy with a low-power source (ie it won't complain if it can't get lots of power from your solar panel when the sun goes behind a cloud).

Next, we choose a solar panel to meet your needs...

A : USB Charging
Check the printed specs on your battery pack. Most of these small 3.6/3.7V battery packs are in the 1,000mAH range (a measure of the capacity of the battery).
If you plan to drain a full battery every 1-3 days...
        SUNLINQ1 -or- SUNLINQ Mini
If you plan to drain a full battery once or twice a day...
        SUNLINQ2
Why these? Because you are mobile, you need a panel that works well in indirect sunlight & lightweight & easy to pack. The heavy crystalline panels, and gimmicky pocket chargers are simply not your best fit.

B : 12V Charging
Check the printed specs on your battery. Most of the 7.2/7.4V batteries are in the 1200mAH range (a measure of capacity), with camcorders often upwards of 2,000mAH.
If you plan to drain a full camera battery every 2-3 days...
        Powerfilm 5 -or- Powerfilm R-7
If you plan to drain a full battery once or twice each day...
        Powerfilm 10 -or- Powerfilm R-7
If you plan to drain a full camcorder battery each day...
        Powerfilm R-14 -or- SUNLINQ4
Why these? Sensitive solar cell technology gives you power in a wide range of sunlight conditions, plus they are the lightest available for packing. The Powerfilm "R" panels are made for boats, kayaks & wet places.

C : NiMh AA Charging

I'll go on the assumption that you have good quality AA's with capacity of at least 2,000mAH.
If you plan to drain a pair of AA's every day...
        Powerfilm 5 -or- Powerfilm R-7
If you plan to drain four AA's each day...
        Powerfilm 10 -or- Powerfilm R-7
Why these? Sensitive solar cell technology gives you power in a wide range of sunlight conditions, plus they are the lightest available for packing. The Powerfilm "R" panels are made for boats, kayaks & wet places.

Putting It Together...

That's about it for solar-direct charging of your camera. Put the battery in the charger, plug the charger into the solar panel, and expose to as much sunlight as possible.

Considerations & "What If's"...

"What if I want to charge at night when it is more convenient?"
Simply use a solar storage battery to store your solar panel's power during the day. Then you can plug in your charger anytime, day or night, to charge your camera battery at full speed (ie not dependent on the sunlight conditions from moment to moment).
Which solar storage battery you choose depends on your solar panel type (USB or 12V), and how much storage you want for the locations you travel to, and of course your budget.

"I already have a solar panel... can I use it?"
Absolutely. The same recommendations outlined above apply, but you will need to compare the output of your panel against my recommendations in order to properly budget your power. For example, if you have a little 0.5W pocket USB charger, then it will take 4x as long to get the same power as the SUNLINQ1 recommended above. Consider this against your desired camera usage.
If you have a 12V solar panel, but the above discussion led you to a USB solution, then use the 3-Way charger.

"What if I have other things to charge?"
Once you have access to your own power everywhere you go, you soon find the need to charge more than what you originally intended. Plus, you will probably want to sell power to the other people in your group & recoup some of your investment!
Anyway, if you want to add something small like a phone or iPod, the above systems will handle the small additional demand. Use your USB Sync cable in the case of USB solar panels, and use your device's car adaptor if you have a 12V solar panel. Plug & play.
Smart Phones & Tablets Alert!
These things are fussy, and demand a minimum amount of power (500mA in the case of an iPhone, 1500mA in the case of an iPad). So, these will not charge solar-direct easily... use a solar storage battery to provide the necessary power.

"What if I have a lot of extra things to charge?"
We will need to talk about it to make sure you get the equipment that will cover your needs properly. Send me an email (see the sidebar or ModernOutpost.com), and we'll review your equipment list, destination, time of year, and mobility to create a system & power budget.

Thanks for reading! I hope you found it useful.
Be sure to tell your friends, colleagues, & travel mates!
Let me know if you have any questions or comments, I am always happy to help.

Considering A Goal Zero Solar Kit? Read this first.

Everyone in the solar industry has at least heard of Goal Zero by now. They are the American portable solar power company that was born out of african humanitarian aid projects. Goal Zero builds some fantastic products... heck, I sell a lot of them myself (see here). And Goal Zero does a great job of marketing their equipment, which is why you can find it almost everywhere solar panels and innovative outdoor gear are sold. But, should they be on your equipment short-list?

Just as the old saying goes: "There is a tool for every job", so it is with packable solar power systems. In this article, I will take a look at several popular Goal Zero power kits, suggest the best applications for them, and suggest excellent alternatives that may be better suited to your specific needs.

A few numbers to help you compare:

     Smart Phone battery full charge = 5-6 Watt-Hours
     GPS receiver battery full charge = 8+ Watt-Hours
     Tablet PC battery full charge = 20+ Watt-Hours
     Laptop battery full charge = 50+ Watt-Hours

Onward...

The Goal Zero Switch 8 : $139.99 (est)

This is the latest kit release from Goal Zero. It features their Nomad 3.5 folding panel, with the new Switch8 lithium USB battery pack. Following are the key specifications...

     Solar Panel Type : Monocrystalline

     Max power generation : 2.5 Watts (USB)
                or 3 Watts if using the Guide10 battery

     Power Storage : 7.92 Watt-Hours
     Max output : 1,000mA @ 5V USB
     Total Weight : 310g (11.2oz)

The verdict:
Like all Goal Zero products, this kit is very well built to take the abuse of wilderness use. The monocrystalline panel is best suited to direct sunlight, so it makes sense for regions that have a lot of sunshine (Africa, SW USA, Mexico, etc).
But, an integrated Voltaic charger like the Fuse 4W provides better performance with the same solar technology for less money, plus you get a very nice gear case...

Voltaic Fuse 4W : $129.99
     Solar Panel Type : Monocrystalline

     Max power generation : 4 Watts
     Power Storage : 11.1 Watt-Hours
     Max output : 1,000mA @ 5V USB
     Total Weight : 600g (20.8oz)

So, that being said, what USB solar charger would be my lead recommendation for difficult Canadian & other North American locations? If there is a good chance you will get partial shade, variable sun exposure, variable weather, or will be working at high latitudes, then the following will be the best options for you...

1. SUNLINQ1 + Voltaic V11 : $99.99 (est)
        Solar Panel Type : CIGS thin film
        Max power generation : 2 Watts
        Power Storage : 11.1 Watt-Hours
        Max output : 1,000mA @ 5V USB
        Total Weight : 2.21g (7.9oz)

        - lighter weight, more sensitive in low-light & partial shade,
          & more affordable

2. SUNLINQ2 + Voltaic V39 : $189.99 (est)

        Solar Panel Type : CIGS thin film
        Max power generation : 4 Watts
        Power Storage : 39 Watt-Hours
        Max output : up to 2.1A @ 5V USB (supports tablets)
        Total Weight : 540g (19oz)

        - More power in any light condition, greater sensitivity,
          & greater power storage.

The Goal Zero Guide 10 Plus Adventure Kit : $119.99 (est)

This is the most popular Goal Zero kit. It features their Nomad 7 folding panel, with the Guide 10 Plus USB battery pack. This kit has all sorts of strange specifications... it says the rated output of the panel is 7 Watts, but the most you can get out of it is 6 Watts (USB) if connected directly to the Guide 10 pack using the special cable.
Following are the key specifications...

     Solar Panel Type : Monocrystalline

     Max power generation : 2.5 Watts (USB), 3 Watts (12V socket),
                          or 6 Watts via special Guide10 interface cable

     Power Storage : 12 Watt-Hours
                         (using 4 NiMh rechargeables - included)
     Max output : 1,000mA @ 5V USB via Guide 10,
                         (see above for max solar-direct performance)
     Total Weight : 540g (19.2oz)

The verdict:
I find this kit to be a bit disappointing... for $120 you get a very low-power 12V charger, and a very ordinary USB charger. I like the concept of the dual-voltage Nomad panel, but it is NOT a 7W panel! At the performance level of the Nomad 7, you should not expect to be able to charge many things directly from the panel... certainly not your iPhone or iPad. The monocrystalline solar cell type is best suited to direct sunlight, so it makes sense for regions that have a lot of sunshine (Africa, SW USA, Mexico, etc), so you might get frustrated in non-intense sunlight.
The Guide 10 performs well, and being able to use NiMh cells comes in handy, but even it lacks the punch to support many of the new 'smart' devices while they are running.

So, what alternatives would I recommend for Canadian latitudes & most North American locations? What systems would properly support 12V & USB devices in difficult weather & mountainous terrain?...

1. Powerfilm F5 + Novuscell 24 : $279.99 (est)
        Solar Panel Type : Amorphous thin film
        Max power generation : 4.8 Watts (12V)
        Power Storage : 24 Watt-Hours
        Max output : approx 20 Watts (2.1A @ 5V USB -or- 2A @ 11.1V)
        Total Weight : 340g (12oz)

        - lighter weight, more sensitive in low-light & partial shade,
           & powers far more 12V & USB devices (which is the point!)

2. Powerfilm R-7 + Voltaic V60 : $289.99 (est)

        Solar Panel Type : Amorphous thin film
        Max power generation : 6.9 Watts (12V)
        Power Storage : 60 Watt-Hours
        Max output : up to 48 Watts @ 12V, 16V or 19V, plus 2.1A USB
        Total Weight : 840g (29.6oz)

        - More power in any light condition, greater sensitivity,
          waterproof solar, & greater power storage,
          varied output voltage support.

Keep these options in mind, as they form a foundation for looking at the next level of portable power. This brings us to the last of the three Goal Zero kits I will look at in this article...

The Sherpa 50 Solar Recharger : $349.99 (est)
Goal Zero has put this kit together to address the varied needs of remote camps, serious trekkers, and anyone who has a comprehensive list of electronics to keep running while miles from civilization. The 13W Nomad panel is a good match to the Sherpa 50, and the combination supports both 12V & USB devices.
Here are the details...
     Solar Panel Type : Monocrystalline
     Max power generation : 13 Watts (12V), 5W (USB)
     Power Storage : 55 Watt-Hours (Sherpa 50 v2)
     Max output : 75W @ 12V & 1.5A @ 5V USB
     Total Weight : 1.22Kg (2.7 lbs)

The verdict:
This is a good kit, but again designed for sunny, tropical environments. The Nomad 13 panel provides solid 12V output, plus a USB option that is strong enough for fussy USB devices (in full sun of course). If you really need household AC power (not recommended), there is an inverter option for the Sherpa and this in itself is unique for a lithium system.

So, what alternatives to the Sherpa 50 Solar Kit would I recommend for Canadian latitudes & most other North American locations? What systems would properly support 12V & USB devices in difficult weather & mountainous terrain?

First, I will dispense with an AC inverter option. This is rarely needed as there are more efficient DC options available for most devices. Therefore we are left with specifying a comparable solar panel, but with improved low-light sensitivity, and bundle it with a storage battery that supports 12V & USB devices.
Here they are...

1. SUNLINQ4 + Brunton Sustain : $444.99 (est)

        Solar Panel Type : CIGS thin film
        Max power generation : 12 Watts (12V)
        Power Storage : 72 Watt-Hours
        Max output : up to 60 Watts @ 12V, 16V or 19V, plus 2.1A USB
        Total Weight : 937g (2.06 lbs)

2. Powerfilm R-14 + Voltaic V60 : $379.99 (est)

        Solar Panel Type : Amorphous thin film
        Max power generation : 13.9 Watts (12V)
        Power Storage : 60 Watt-Hours
        Max output : up to 48 Watts @ 12V, 16V or 19V, plus 2.1A USB
        Total Weight : 1.14Kg (2.5 lbs)

This concludes my little report on Goal Zero and what alternative equipment combinations I would recommend for Canadian & North American locations. Again, the point of the exercise is to pack along equipment that will work under the widest range of conditions. Goal Zero equipment is good, but not the best option in challenging northern latitudes.

I understand that I presented quite a few numbers here. Sorry about that. I tried to keep them simple so that you can make meaningful comparisons between devices. If you have any questions regarding anything I have presented here, please do not hesitate to contact me.
Cheers!

Performance Report: Powerfilm R-14 & Voltaic V60

A quick report of charging a Voltaic V60 battery pack from a Powerfilm R-14 rollable solar panel...

Solar Panel : Powerfilm R-14
Battery Pack : Voltaic V60
Connectors : Stock CLA connectors provided with the panel & battery
Mounting : 30-Degree slope, facing due south

Date : April 3, 2013
Location: Courtenay, BC, approx latitude 50 degrees north
Weather : Bright overcast
Test duration : 5hrs (10:30am - 3:30pm)

The battery started out with 2 of its 5 status lights, indicating a charge status of approx 40%. At the conclusion of the test, the battery had all 5 status lights turning on in sequence, which would indicate it was in the 90% state-of-charge range. Therefore approx 50% of the battery's capacity was added over the 5 hour period.
The V60's capacity is 60 Watt-Hours, so a 50% charge would amount to 30 Watt-Hours.
This result would indicate that the Powerfilm panel was producing an average 6 Watts of power over the duration of the test, which equates to 43% of its rated output. Given the weather conditions, this was an excellent result.

Conclusion...
I was very pleased with the results of this test. Not only did the Powerfilm panel perform well under the conditions, but the Voltaic V60 battery appears to be very efficient at storing the power it receives. In summer sunshine, this same time period would completely fill the V60.
I have no reservations about recommending this panel & battery pack combination.

Note: This was a static test. The Powerfilm R-14 will achieve nominal charging voltage for the V60 in as little as 10% of full sunshine. Be aware that panel orientation, obstruction, time of day, and weather conditions will all affect the performance.

Please feel free to contact me with any specific questions or comments.