I have a 2009 Jayco Penguin with a battery installed, which is charged when connected to 240v power. We stay mostly at parks with power, but I'm interested in visiting some spots which don't have power and water. Although the battery would probably last a few days (to pump water and run LED lights) without 240v charging, I'm interested in attaching a solar panel to top up. There is an Anderson plug at the drawbar and I'm told I could simply attach the panel there to charge the battery. My question is, do I need to run a controller/regulator to do this? Logic suggests I should, but an acquaintance raised doubts. Can anybody shed any light on it for me?
Depending on the style of panel you go with, some have regulators included such as Solbian (some of) and most portable folding styles also. Even though one of my set ups which I use when away on remote islands came with a regulator, I decided to upgrade to a victron regulator with bluetooth connectivity and other features such as being able to set timers for lights and multiple battery charging profiles. If you are considering lithium batteries at any point, you will need a regulator with the correct charging profile or as in my case multiple profiles which will help extend the life of the battery's.
Strictly speaking with a smallish panel & a reasonable sized battery the panel could be connected to the battery & charge it. HOWEVER it would require you to monitor the battery voltage very regularly with a multimeter, & to know at what voltage to disconnect the panel to prevent overcharging.
It's a rough & ready solution which van be used in an emergency, but a solar regulator if far easier & preferable as it 'automates' the cut off by going into float mode when the battery is full.
Solar regulators are also multi stage 'smart' chargers generally, Bottom line is that even one of the el cheapo 'throw away' regulators often supplied on the back of panels will be better than no regulator, but paying a bit more gets you a regulator which will look after your battery better (extending it's life) , will (if MPPT harvest a little more solar output in less than optimal situations (first & last hour of sun during the day, or overcast conditions) and allow you to mount the regulator close to the battery (rather than at the panel) which also creates greater efficiency. Basically in a small system 'every little bit helps'.
Assuming your battery is not lithium, alarm bells ring (for me) when you say 'Although the battery would probably last a few days' because although this may be correct, if doing so involves discharging the battery below about 40% on a regular basis & not being able to recharge it fully soon after will result in much shorter battery life. Best to think of the available amp hours of your battery being half what is stated on the battery .......... unless of course you consider shorter battery life a reasonable trade off for having the power when you need it.
Lifespan of most of the deep cycle batteries we use in our RV's can easily be 10 years+ if 'treated well', but if used until 'flat' on a regular basis that period can easily be reduced to 12 months. It's a choice. Many RV'ers & 4wd'ers accept a shorter life because they don't have space for extra batteries and/or the means to fully recharge them every 24 hours.