Solar Panel - Habitation or Cab Battery Priority?

[timabob]

I have noticed with my newish Hymer which has a solar panel and two habitation batteries, that when in full sun the gauge for the Cab battery is always at the top of the scale, meaning it is getting plenty of charge and the habitation batteries are usually just sitting at 12.5v or maybe 12.7v.

 

The habitation batteries do charge up from the Solar panel, but much slower than I was expected.

 

Anyway, I took it in to have it checked and it was confirmed that the solar panel is working fine, but whoever set it up (I bought the van in Germany) had prioritised charging the cab battery and the leisure batteries just get a trickle.

 

This seems back to front to me, but the English dealer said that some UK solar panels are set up this way so as to keep the cab battery charged through winter when motorhomes often sit unused for long periods.

 

We intend to use our van every three weeks or so over this winter and from next winter we are going to be travelling full time and hoping to stay off site for much of the time.

 

My question is should I ask for the wiring to be switched so the habitation batteries are getting the main charge and the cab battery a trickle or is there some disadvantage with this idea that i'm not seeing?

[colin]

If you use much power you will need the hab batteries on priority else they may well struggle to keep up with use.

The set up you describe would work for anyone who mainly relies on ehu on site.

[urbanracer]

When I had my solar panels and regulator etc, fitted the fitter asked how much charge the leisure and starter batteries should be set, we agreed at 20% to starter and 80% to leisure.

This has worked OK for last 4 years and the starter battery is fully charged even when the van is not used over winter.

[mikejkay]

My system(150w panel) is set up to 70/30 habitation/vehicle. However, I use my vehicle frequently and I occasionally run a microwave and a toaster via an inverter. My TV is mains powered and also run via the inverter. I've had this system on two motorhomes and it works fine.

[aandncaravan]

It depends on the size of Solar Panel you have, the regulator capability, the battery age/technology, where you live/holiday and your usage.

 

Sometimes the priority is given to the Starter battery if the MH is used infrequently and the Starter battery has a high drain from items like a Tracker, after market alarm, Car style Remote Control Stereo (all can have quite a noticeable standby power draw) etc. Under these conditions the Habitation batteries (if good) will hold their charge and not need topping up, but the Starter battery might take a hit as a Tracker can run down a Starter battery in 2 - 3 weeks.

 

In your case, with frequent use, it sounds like your Starter battery is unlikely to drop much. But your usage of the Habitation batteries are likely to be higher so we would suggest it might be better to change priority, provided you don't have high consumers, like a Tracker connected to the Starter battery.

If you do have any high consumers, consider having them moved to run off the Habitation battery.

 

There are so many variables with Solar Power and the way it is used, that a setup that works for one, won't for another. A few months ago we had two couples turn up for a check because the Williams had copied their friends, the Owens, Solar setup. Recommended because it had worked so well for them.

Both Motorhomes arrived so we could find out what was wrong with the Williams van. Once we resolved it, they were all then going to head down the Welsh West Coast on a holiday.

A quick examination revealed that they were both working perfectly. Lots of questions and we established very different usage.

The Owens liked to go to for walks after Tea, returning back to the MH late at night, when they pretty much went straight to bed. They used almost no 12 v during the evening and the Solar Panel was easily able to put back what little was drawn.

The Williams would put the TV on while they made Dinner. They would then sit down to watch it or read, with several lights on, until late into the evening.

Their 12v usage was much higher than the Owens, hence the Battery getting lower as the holiday progressed. All we could do was advise an EHU overnight somewhere during their tour.

 

A Solar setup isn't something that you can install based on a particular setup working for someone else, as usage, like where they holiday may be key.

Remember that the Solar Harvest in the South of France in Summer can be 10 times greater than that on the slopes of Inverness in Winter.

Their 12v demand in Montpelier may be very small (no lights needed no Heater fan running through the day/night, etc.).

Yet the 12v demand in Inverness may be 3 times that in Southern France, just from running the Heating fan/pump through the night.

 

 

You seem to be basing most of your use in Winter when the Solar gain is low anyway so swapping the priority around might not buy you much? Maybe get them to put in a switching system so you can see what works for you?

 

 

 

 

 

 

 

 

 

 

[Taffyjimbob]

Fit a Photonic Universe dual battery solar controller, it will give you the abillity to set the charge from 10% car battery 90% leasure battery/batteries to 90% car 10% leasure. Whilst in storage for any length of time set 90% car 10% leasure. When on the road or wild catting set 10% car and 90% leasure. Costs about £35. It also has overheating sensors. Had mine 3years.

[rogher]

I think it’s wrong that your panels should be prioritised to charge the starter battery. Find out how your controller works and how the priority can be changed. If you move regularly it may not matter so much but, if you spend more time stationary and using 12V, you’ll need to prioritise the charging for the habitation batteries. If the vehicle is not on EHU when stored, you should swap the priority around because there’ll be no drain on the habitation battery but the starter will most likely be serving an alarm. Some controllers can apportion the amount of charge provided to each bank but others will only charge a second bank after the first is fully charged.