Solar question - charging multiple batteries

I thought this question had already been answered on the forum, but I can't find the discussion. Is there a problem with charging the onboard TD battery from a solar panel while other batteries are also charging in the TD? For example, will the TD battery charge from the solar panel just as well if a laptop (or CPAP) battery is charging in the TD?

I seem to recall that the TD battery will not charge as well from solar if there is a second battery also charging.

I recently was charging the TD battery from solar and also charging a cpap battery (plugged in to the 12V outlet). When I came back later in the day, the cpap battery had not charged and the TD battery had barely charged.

But perhaps this is not a problem and the weak charging was a result of the lack of sun due to the season (February).

or perhaps this is an issue even if using shore power to charge the TD battery (and cpap battery)...


Thanks for your thoughts.

-Al

 

I just set up with a Yeti400, a Renology 100w panel w/o the inverter, and some cables.

Basically I had the Yeti 400 hooked to a 100 watt foldable solar panel, and ran an ac power cord from it to the input AC power on the back of the trailer. Using my CPAP machine (Autoset 10, humidity turned off) at night, for about 6-8 hours per night, the yeti easily charged me all night long, plus topped off the trailer battery every day. This used about 20-40% of the yeti per night, most of which was probably my horribly inefficient powering of the trailer through two DC->AC and AC->DC inverters.

So for someone who is non-handy or in my case doesn't want to drill a hole in the trailer for solar hookups, this was an easy solution.

The yeti is about 400 bucks, the solar panel about 250, plus some cabling for about 40 bucks (yeti MC4 solar to 8mm adapter cable, and a 30' 8mm cable.)

The Renology panels are portable (someone else mentioned these on the forum too), with my regular 100' power extension cord (also sucking off power), I could put the solar panels anywhere in a 130' circle from the trailer to stay sunny while the trailer is shady and keep it connected w/AC on the trailer, giving me AC all day on the trailer, power all night.

This is a less than efficient way to do it, but easy. It also takes out any issue of battery type matching for charging.