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Solar Charger for Motorhome Starting and Leisure Batteries

Posted by in Ask Bill, Boats and Campers on Jun 03, 2020 . .

Customer question (received via email 30th May 2020):

My Motorhome has 2 x 110ah leisure batteries fitted in parallel and a 90ah vehicle battery. What would be a suitable solar trickle charger to keep these topped up during storage with no drain from the leisure batteries and an alarm/tracker/radio drain from the vehicle battery - I intend to alternate the charging regime between leisure and vehicle during storage. I can mount the panel in unshaded south facing location outside of the vehicle. 


Willgen Reply (Email from Bill 1st June 2020):

Hi Paul,

Many thanks for getting in touch.

For the situation you describe I would recommend an Optimate 40 with an additional Optimate O1 Battery Lead. The 40W solar panel should be large enough to provide enough charge to both battery banks throughout the year when charging is alternated between the two (assuming solar panel outside, South facing, unshaded).

Use the O1 Battery Lead supplied with the charger to connect to one battery bank and the additional O1 Battery Lead to connect to the second battery bank. Alternating charging between the two banks then is simply a case of unplugging from one battery and plugging into the other using the Optimate charger's in line plug and socket arrangement. You could use the crocodile clips (supplied with the solar charger) to attach to one of the batteries rather than buying an additional O1 Battery Lead, but hard wiring to the batteries with the O1 Battery Lead is a much better option as it provides a safer and more reliable battery connection.

The solar panel comes with 2m of cable attached so you may also require an extension cable (4.6m) to give you enough reach from the solar panel to the charge controller/battery.

The solar panel can be permanently mounted outside. The charge controller is splash proof but is not designed for outdoor installation so needs to be installed in a sheltered location. The charge controller should be positioned close to the battery so is normally positioned inside the vehicle (under bonnet or in/near battery compartment) in any event.

Links to products mentioned above:

I hope that this helps. All the Optimate products listed above are currently in stock and ready for quick despatch.

Kind regards


Last update: Jun 03, 2020
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