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 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...

Posted by in Ask Bill on Apr 14, 2020 .

Customer question (received via email 5th April 2020):

Hi. I am thinking of getting an Optimate solar battery conditioner/charger for my Porsche Cayman (3.4 litre flat 6 engine) during the current period of driving restriction as I don't have power in my garage. I have a couple of questions:

1) What size charger would you recommend? I have an off street parking space where the car would be parked pretty much due East but I could potentially leave the panel outside the car facing south (I assume the panel is weatherproof) during the day. However I do not have anywhere I can fix the panel permanently so would not want to do this...

Posted by in Ask Bill on Mar 02, 2020 .

Customer question (received via email 1st March 2020):

Hi there

I am looking for some advice please.  I have a Land Rover Defender 110 which is my second vehicle and therefore doesn't get used that much. I use it as part of my Scouting ( carrying equipment,towing trailers, safety vehicle to walking events etc). I also use it as a volunteer for a 4x4 response group where we can get called out by the authorities to assist in bad weather, floods etc. Other than that I tend to run it occasionally just to keep it ticking over. 

I need to look at a trickle charge system to keep the battery topped up when I am not using it. The car is...

Posted by in Ask Bill on Oct 15, 2019 .

Customer question (received via email 14th October 2019):

Hi, I have a VW T6 Transporter Camper with a Varta 000 915 105 FC 12v 70Ah EFB+ Stop/Start battery.

Would the Optimate 10W Solar Charger be compatible with this please? Ideally, I want to charge via the dashboard 12v cigarette socket (which is on without need for the ignition).

Many thanks.


Willgen Reply (Email from Bill 15th October 2019): 

Hi Nigel,

many thanks for getting in touch.

Yes the Optimate 10W is compatible with your VW T6 battery.

If positioned outside, in an un-shaded South facing location. the Optimate 10W solar panel will be...

Posted by in Ask Bill on Aug 15, 2019 .

Customer question (received via email 14th August 2019):

I'm looking for a solar charging system for my motorbike which is kept in a garage with no mains power. I have seen the OptiMate 10W Solar Charger (OP10) on you website. Do you think this would do the job. Do i need anything else in the way of connections to attach to the bike? Also is there a mounting bracket or anything available?

Thanks Chris

Willgen Reply (Email from Bill 15th August 2019): 

Hi Chris,

many thanks for getting in touch.

The Optimate 10 is ideal for maintaining your 12V motorcycle battery.

The Optimate 10 comes with a weatherproof battery...

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