Car battery parasitic drain.

[ericmark]

The Jaguar XE is not a problem now lock down has ended, it was due to non use with lock down that I had problems.

However I am told it should be charged from the under bonnet connection, not from the boot, due to the engine management computer which works out when the battery needs charging. No longer is the alternator a self contained unit, the stop/start system, and over run charging all controlled from the engine management.

Even with older cars, the charging of the battery is not that simple. In the main it is a compromise, and although 13.2 volt will maintain a battery, cars and vans tend to use a higher voltage, 13.8 to 14.2 as they realise it has a very short time to recharge the battery, in the days of the dynamo the two bobbin regulator was set to 16 volt open circuit, would never reach this voltage once battery connected, but that was the setting.

Many items using lead acid today use stage charging or pulse charging, what seems a simple battery charger from Lidi if left on the battery with alternate between 12.9 and 14.4 volt, each time the volts drop charge rate changes, and it takes it to 14.4 volt, that may only be for 2 minutes every 3 days, but the higher voltage pulse better equalised the cells in the battery to a float charge.

Where the battery is used then charged, be it a mobility scooter, fork lift, milk float, then stage charging is used, so until the current drops to a predetermined level it charges at 14.8 volt, then at the set point drops to 13.8 volt. However this does not work well if battery used while being charged, like narrow boats, they use pulse chargers, and the charger measures the volt decay after each pulse.

The standard regulator used for solar panels and wind chargers often uses pulse charging, it is also common for it to have a built in inverter to change the incoming voltage to out going voltage, so the solar panel will have an output of 9 volt morning and evening but 16 volt mid day and the regulator selects the voltage at which the panel can produce maximum watts.

The regulator needs energy to work, so only used with the larger arrays, so the performance of the solar panel is very dependent on the regulator used, so we talk about PWM and MPPT regulators, and I know they exist, but never really used them. If you look here at the range there are so many, and they can get rather costly.

To get more info likely a narrow boat forum will help, as they use solar panels a lot.

My experience pre dates the MPPT back in late 80's on the Falklands both wind and solar was used to power electric fences with a lead acid battery, although the wind charger had 3 times the output to solar panels, the solar panels were better, as sun shine every day, only time solar panels failed was in the snow.

In the 70's we would remove battery when car not in use, or at least battery terminal, the car radio which had an anti theft code changed that, although many radios are no longer coded, as they are special to the car, my Honda Jazz never needed a code when battery changed, but Vauxhall Agila was cheaper to buy new radio than to get the code.

I know if the battery is changed on the Jag, the engine management needs telling, no longer a simple job. But Rover 45 is an old obsolete car, so it may use radio codes, but is not that old so could have some of the modern features, the problem is being obsolete can't go to a manufacturers web site to find what it has.

I note caravans with built in solar panels, would be great if the car had a built in solar panel, but no, you need to either mount it exterior or use mains. I would look at those designed for caravans they are large enough to use MPPT regulators so should work OK in the winter.