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Solar Charger for Defender's Twin Batteries

Posted by in Ask Bill, Solar Lights and Chargers on Jun 15, 2020 . .

Customer question (received via email 12th June 2020):

Good afternoon.  I have a Land Rover Defender with a twin battery set-up (main and leisure).  Which trickle charger would you recommend please?  Thank you, Nick.

Willgen Reply (Email from Bill 15th June 2020):

Hi Nick,

Many thanks for getting in touch.

Assuming that you want to charge both batteries I would either go for one solar charger and swap it between batteries, two separate solar chargers with one solar charger dedicated to each battery or for a single larger solar panel wired back to a dual battery charge controller.

Single Solar Charger

I highly recommend Optimate Solar Chargers. If you don’t mind swapping the charger between the two batteries (easy to do thanks to the Optimate in-line plug/socket arrangement) buy a minimum of an Optimate 20 and simply swap between batteries as required. The higher wattage the faster it will charge your batteries (i.e an Optimate 40 will charger twice as fast an Optimate 20). Each Optimate solar charger is supplied with one set of O1 Battery Leads (with ring terminals for bolting to your existing battery terminal connections) and one set of crocodile clips - easily interchanged). You may want to buy an additional set of Optimate O1 battery leads so that both batteries are "hard wired" to the charge controller when in use rather than crocodile clips on one of the batteries which is less satisfactory.

Two Separate Solar Chargers

This option has you fit a dedicated charge controller to each battery. The Optimate 10 will be sufficient to protect against natural battery drain of one battery if well positioned (South facing, un-shaded), if there are significant drains on the battery, the panel is poorly positioned or you want to provide extra charge (for the leisure battery for example) go for a larger charger. You could go for an Optimate 10W on the starting battery and an Optimate 20 (or larger) for the leisure battery for example.

Single Solar Panel with Dual Battery Charge Controller

This option is a bit more involved and will involve some simple DIY wiring but has the advantage that a single panel is required which may be helpful if you are permanently mounting it to the outside of the vehicle.

You can use a glass fronted panel or might find a semi-flexible panel more useful depending on where you intend to mount the solar panel. I would recommend one of the following solar panels (depending on your choice to suit your situation) :


If you just want to replace natural battery drain a 20W panel will be large enough if you can position the panel well (South facing un-shaded). If the panel position is less than perfect,there are draws on the battery (alarms etc) or you would like greater output to allow the leisure battery to be charged faster when out and about (to replace power you have used) go for the largest solar panel you have room for on the vehicle and that's within your budget.

In addition you will need a:

We supply a standard 2m Wire Loom to run between battery and charge controller - you would need two of these. If you need a longer length to go to one of the batteries let me know and I will size it for you.

Sorry for the long reply - I hope that it helps. If you require any further information please get in touch. You can place an order online or give me a call if you prefer.

Kind regards


Last update: Jun 17, 2020
Willgen, Church Farm, Wartnaby, Melton Mowbray, Leicestershire, LE14 3HU
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