Solar charger for Motorhome Starter Battery

Posted by in Ask Bill, Solar Lights and Chargers on Jan 17, 2021 . .

Customer question (received via email 17th January 2021):

I'm looking for a solution to a problem i have with my A class motorhome, it is equipped with a solar panel to maintain 2 x leisure batteries and 1 x starter battery. I have noted overwinter that the starter battery has flattened and is not recoverable, the leisure batteries are fine and seem to be maintained without issue, i think it may be something to do with the way the battery monitors voltage relay switches, as i understand it takes care of the leisure batteries first and then the starter battery.

My thought is to fit a stand alone solar panel in the windscreen whilst the vehicle is in storage to plug into the starter battery to give an independent top up to the starter battery.

A. is this possible?
B. Are there any risks to doing this that i need to be aware of?

Regards,    Peter.  

Willgen Reply (Email from Bill 18th January 2020):

Hi Peter,

Many thanks for getting in touch.

In answer to your questions: yes it is possible to add use an independent solar charger to charge the starting battery and no there are not any risks associated with doing so.

It is fine to have multiple chargers (solar or not) connected to the battery in parallel.

If putting a solar charge in the windscreen bare in mind that for best performance orientation of the solar panel should ideally be due South in and un-shaded position. Also be aware that placing the solar panel behind the windscreen, particularly if it is tinted, will reduce the solar panel output slightly.

For this reason if orientation is good and shading is minimal I would recommend using an Optimate 20 Solar Charger. Go for a larger charger (optimate 40 or Optimate 60) if orientation is poor or if there is significant shading.

All Optimate solar chargers come with a set of Waterproof Battery Connection Leads (for permanent connection to battery) and a set of  Crocodile Clips (for temporary battery connection). Optional suction cups are available for the Optimate solar chargers and there are numerous connection accessories available to make connecting to the vehicle's battery as simple as possible.

Products that may be of interest:

Optimate 20 Solar Charger

Optimate 40 Solar Charger

Optimate 60 Solar Charger

Suction Cups for fixing to windscreen

Cigarette Lighter Plug Socket Adapter:

OBDII Plug Connector:

Further details of all of the above, including solar panel dimensions, can be found on our website product pages. Please note that if using the cigarette lighter socket to connect the solar charger the socket must remain live when ignition off and the key is removed.

I hope that this helps.

All Optimate products are currently in stock and ready for rapid despatch should you decide to place an order. 

Kind regards



Last update: Jan 28, 2021
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