Which 12v solar battery charger?

Posted by in Ask Bill, Eco Products, Boats and Campers, Solar Lights and Chargers, Off Grid Solar and Wind on Apr 22, 2013 . .

Putting a motorcycle, car, vehicle, caravan or boat away for winter or have a vehicle that is not used for long periods of time? 12V solar chargers are perfect for year around maintenance of 12V vehicle starting and caravan/boat (leisure) batteries. But which is best for you?

There are numerous 12V solar trickle chargers available and choosing the right one can be difficult. Cheap is tempting but not always cheerful and who should you believe when it comes to performance and quality?!

Well worry no more. Here is Willgen's definitive guide to choosing the right 12V solar battery charger for winter battery maintenance.

What size solar charger do I need? 

Batteries naturally drain over time even if there is nothing being powered by them. Prevention of this natural drain can be achieved by applying a "maintenance" charge to the battery. If sized correctly, solar chargers are an ideal way of providing this maintenance charge meaning you can always come back to a fully charged battery even in mid winter.

Whether you are wanting to maintain a starting battery or leisure battery doesn't really matter. The size of solar charger you require to protect against natural battery drain depends on the size of your battery. Battery size is measured in amp hours (Ah).

10W : 100Ah 

As a rule of thumb we work on a ratio of 10W of solar power for every 100Ah of battery capacity. This will ensure adequate winter battery maintenance and provide a some extra charge in the summer (which could be used to offset power used for 12V lighting and appliances used in boats, campers, caravans etc). 

Less than 10W : 100Ah 

If you are just wanting to keep a vehicle battery topped up during the sunnier summer months this ratio can be reduced.

Any amount of solar input will help, but the lower you go the greater the chance of coming back to a drained battery!

The smallest solar charger we sell is the 1.5W 12V Solar Trickle Charger  - this would be okay winter maintenance of a small 12V battery such as that used on a motorcycle or possibly a small car.

Greater than 10W : 100Ah

If there additional drains on the battery (a car alarm for example) or the solar panel can not be positioned in an ideal (un-shaded, South facing) position the ratio should be increased.

If in doubt go bigger! As above, any amount of solar input will help, but the bigger you go the greater the chance of coming back to a fully charged battery!

If you are charging a 12V battery that will provide you with power for 12V lighting and appliances (typically on a boat or in a camper or caravan) you will need to exceed the 10W : 100Ah ratio. There is really no limit to by how much you exceed the ratio as the more solar panels you install the more power you will have available to use.

If you exceed the 10W : 100Ah ratio (and there is often very good reason for doing this) it is important that your solar charger incorporates a solar charge controller  (solar regulator ) to protect your battery from overcharging. The solar charge controller  will also manage battery charging to maximise solar output and may, depending on model, give you system status and battery state of charge information as well. All of our 12V vehicle solar chargers incorporate a charge controller if one is required so you have no need to worry.

For detailed guidance on solar chargers  for leisure batteries please follow this link : Solar Panels for Boats (and Campers and Caravans) . 

Solar trickle charger, solar charger, solar panel? I'm confused!

Solar chargers  are referred to as all of the above. All of the solar panels and 12V solar chargers on our website are designed for 12V battery charging duties so really all you need to worry about are a products individual features and the size (expressed in Watts or "W").

We have a range of small 12V solar chargers designed specifically for easy use and regular connection and disconnection :

All of the above come with everything required for easy use and installation.
We also put together our own Solar Chargers and can customise these to suit your needs - please ask for details.
Alternatively you can use any of our solar panels for 12V battery charging duties. Popular for use as 12V solar battery chargers are :
Any of our solar panels can be used for 12V battery charging duties :
Last update: Aug 22, 2018
Willgen, Church Farm, Wartnaby, Melton Mowbray, Leicestershire, LE14 3HU
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