Thanks, that's really useful. I'm more and more thinking the battery has had it. You say that you feel the battery is not fully charged. I can add some more information here. Prior to this trip the moho had been in open air storage. Every time I visit, the control panel voltage shows maximum reading, 13.5V. If this is the solar charging, and this has been going on for several weeks with no significant current draw, surely the battery would have been fully charged? And so I conclude that the swift drop in voltage after dark indicates that the battery isn't taking/holding charge?This seems to confirm your battery is not fully charged and the voltage your seeing during daylight is from your solar panel and as soon as it gets dark your seeing the battery voltage without any solar support. You do not say how much solar you have and I suspect its not enough to fully charge your battery bank. As has already been advised, get onto hook up asap and make sure your battery gets a full charge. You, like most of us learn from these experiences and will overcome these problems. Remember you can never have too much solar.
When you get home you might want to consider doing a test on your battery to see how much capacity is left. According to aandacaravans and Alpha batteries once a leisure battery has lost 20% of its capacity it is regarded as being at its End of Life status. I don't agree with that but I'm just and end user like your good self.
So, How does one do a capacity test on their leisure battery ?
Here is a suggestion by autorouter which I have recently tried and you may want to consider.
1. Fully charge the battery, leave it to settle for a couple of hours.
2. Attach a load that draws an amps value of Capacity/20. (for example for a 100Ah battery, 100/20 = 5A.
3. Run the load for 5 hours. The amp-hours taken from the battery is Amps x 5 hours. (for the same example, 5 x 5 = 25Ah. For a brand new battery this would be 25% of the capacity, so it should be down to the 75% level.
4. Let the battery settle for a couple of hours
5. Measure the voltage.
6. Use this voltage, referring to the battery charge/voltage scale (In Lenny HB's post #32) to estimate what percentage charge is left in the battery. For this example, let's suppose it is 12.28V. If it's a Sealed Lead-acid type, that represents a level of 60%. Since you drew 25% of the label capacity, you would expect the voltage to be at the 75% level on the charge/voltage scale. However because the battery has aged, it is now at the lower level of 60%.
7. If the battery is actually at 60% when you expect it to be 75%, its capacity when full is
(60 / 75) x 100 = 80% of the original capacity.
So the battery capacity has reduced due to aging, and is now only 80% of its original capacity .
I forgot to add the charge chart and here it is.
Battery Voltage Chart Volts % 12.7 100 12.5 90 12.42 80 12.32 70 12.2 60 12.06 50 11.9 40 11.79 30 11.58 20 11.31 10 10.5 0
The solar panel came with the moho. I think it's an OEM component, and I think it's around 100W, which is what Pilote offer as an option.