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Ask Bill

Welcome to Ask Bill! If you have a question about our products or need some help and guidance with an off-grid power or lighting project please use our contact form to ask Bill.

You may also find answers to your questions in the numerous Help and Info articles available via this page.


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...

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...

Posted by in Ask Bill, Boats and Campers on Jun 01, 2020 .

Customer question (received via email 10th May 2020):

Hi. Looking for a small solar panel to maintain a charge on a 110Ah rib battery. Need to mount on the stern A frame as boat will have cover on it when not in use, may need 6m of cable or so. The panel will be out in the elements all year. Smallest would be best and I'm guessing I may have to make some sort of backing/mounting plate. Could you let me know what my best options are please.

Kind regards

Willgen Reply (Email from Bill 11th May 2020):

Hi Derek,

Many thanks for getting in touch.

To maintain a 110Ah battery throughout the year (ie through winter as...

Posted by in Ask Bill, Solar Lights and Chargers on May 20, 2020 .

Customer question (received via email 10th May 2020):

I am looking for advice on what type, size and cost I need to install a solar system to keep a car battery topped up when the car is not in use. The panel would have to be left outside as the car lives under a cover when the power would be required.

Any advice would be helpful


Willgen Reply (Email from Bill 10th May 2020):

Hi Jim,

Many thanks for getting in touch.

You need to be looking at the Optimate range of solar chargers for your car.

The size of solar charger required depends on the drain on the battery when the car is parked (i.e alarm etc) and the...

Customer question (received via email 11th May 2020):

Please advise best trickle charger to keep my motor home vehicle 90ah battery topped up while in longterm storage. Thanks Gerry

Willgen Reply (Email from Bill 11th May 2020):

Hi Gerry,

Many thanks for getting in touch.

The size of solar charger you require depends on the parasitic load on your battery (i.e drains on the battery when the motor home is parked up - alarm etc) and how good a position you can get your solar panel in.

If the parasitic load is just an alarm, and you can get the solar panel outside, in an un-shaded South facing position I would suggest an...

Customer question (received via email 27th April 2020):


I am looking to purchase the OptiMate 20W Solar Charger and the OptiMate OBDII to SAE Adapter for a smart fortwo.  I would like to place the solar charger on the dashboard and connect via the obd port.  Car is a 2013 plate.  If all this is OK I will order as soon as I have your reply, also how soon is delivery Thanks Arthur

Willgen Reply (Email from Bill 27th April 2020):

Hi Arthur,

Many thanks for getting in touch.

The solution you suggest will work absolutely fine to keep your car battery charged. You may want to consider purchasing suction cups as well so the...

Customer question (received via email 16th April 2020):

Hi Bill,

A bit of advice please, I have a Landrover Disco 3 running two batteries, main car battery and an Optima Yellow Top aux battery. In everyday use they are run with a split-charge system. The Optima gets little use for most of the year and most of the time does not get much chance to fully charge. I am looking to fit a Solar charging system for the Optima, What would you recommend?

The Optima is rated at 55 Ah (C20) 50 Ah (C5).

Many thanks


Willgen Reply (Email from Bill 16th April 2020):


Hi Mike,

Many thanks for getting in touch.

I would...

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

Please could you recommend a solar powered trickle charger to charge x2 12V batteries on 2 motorcycles at the same time in a part shaded garage location?


Willgen Reply (Email from Bill 14th April 2020):

Hi Alex,

Many thanks for getting in touch.

I recommend Optimate solar chargers for the vast majority of our customer's vehicle charging requirements.  Although it is possible, I wouldn't normally recommend charging 2 batteries on separate motorcycles at the same time with a single Optimate charger. It is not ideal to connect batteries of different...

Willgen, Church Farm, Wartnaby, Melton Mowbray, Leicestershire, LE14 3HU
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