Is the Parking heater volt sensitive?

[yossarian]

Not during our ownership but I can’t account for the previous owner during the 20 months they had it……..?

If they are lightly sulphated you might recover them by keeping them at float voltage (13.6V 14V or or so) for an extended time (a week or two). The easiest way to do this is probably EHU at home if you can.

The sensors will report the battery internal resistance. It looks like this is averaged and then available from 6D (Special function) on one of the vehicle canbuses. Internal resistance is a reasonable indicator of battery health. One day I might try sniff the raw data off the Linbus and correlate.

Obtaining the data from the canbus is about a 10 minute job with OBDeleven. Data will not be accurate if sensors have not been connected to the batteries for some time.

I see LA80 batteries on sale for 80 quid a piece at some place with an expired security certificate (might be a dodgy site). 136 quid a piece from Tanya.

If we assume a voltage drop of 0.4V drawing 10A we can infer a resistance of 40 milliOhms. Typical new AGM batteries of this class should have around 3 milliOhms each or 1.5 milliOhms total.

Edit: adjust voltages for Scottish winter temps.

 

[PeteS]

I would get the battery checked. On my Caravelle with a factory diesel heater when the leisure battery had a low voltage the heater would not work. There are a number of battery chargers that claim to recover batteries that have been left flat by pulse charging the battery. Note that some older battery chargers may not charge AGM batteries correctly so if you are going to try charging the battery make sure you charger will. If your vehicle had a battery left flat then that could be the problem.