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Solar Trickle Charger for Motorhome

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

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 Optimate 20 will be sufficient to keep the battery topped up all year around.

If the solar panel can not be faced South, will be shaded or is going to be mounted inside the vehicle behind glass you will need a larger charger - probably 40W but possibly even 60W depending on how far from ideal the solar panel position is. Please note that mounting behind glass will reduce solar panel output and this will be more significant if the glass is coloured or tinted.

I do hope that this helps. In most cases an Optimate 20W will be fine for a 110Ah battery but it's better you understand what needs to be taken into consideration. If you want to get back to me with more details I will advise if I can.

Optimate solar chargers all come with a connection lead for permanent connection to the battery with a plug to allow easy connection and disconnection thereafter. Crocodile clips are also supplied for temporary use on a different battery. There is a wide range of accessories to help with connection and installation of the Optimate Solar Charger. The 4.6m extension cable may be useful on a motor home, as may be the suction cups that allow the solar panel to be mounted to glass or a smooth surface.

Also included is a charge controller that manages the battery charging process, improves charging in even low light conditions and prevents battery damage through over charging. The charge controller also has led lights that provides charging status information when charging and battery state of charge information when not (either because it's dark or the solar panel is disconnected).

Links to products mentioned above:

Optimate 20:
Optimate 40:
Optimate 4.6m Extension Lead:
Optimate Solar Suction Cups:

I do hope that this helps. All Optimate products, with the exception of the Optimate 10, are currently in stock and ready for fast dispatch.

Kind regards


Last update: May 20, 2020
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