Will a Jumpstart device affect the battery?

[guinchy]

I did a few local miles on Friday and with it being cold and heavy snow on Saturday left the car alone on the drive. Today I intended to have a drive to see High Force in flood. Car opened okay and then I just sat in it for 5 minutes waiting for my wife (turned nothing on or used anything) Pressed the start button and car wouldn't start and doors wouldn't open. Fortunately I followed the recommendations on one of my previous posts and bought a Clarke 600A Jumpstart and got the car started in 5 minutes. Ironically I have a Multibao 12V/24V LED monitor to pick up in the morning to keep a check on the voltage.

This is the second time I have had to use the jumpstart and I wonder if having to use it is permanently affecting the Battery?

[Herbie]

35 minutes ago, guinchy said:

This is the second time I have had to use the jumpstart and I wonder if having to use it is permanently affecting the battery?

The Battery will be affected but not by the jump start Battery pack itself. They are just a good 12V source piggybacking on a dodgy 12V source and using it is neither good nor bad; it's just 'there' and it works.

The problem is that you've had the need to use the Battery pack in the first place.

Every time the car Battery goes flat it sustains some slight damage and loss of capacity (which can be made worse by how depleted it is and how long it's been in a depleted state). The following figures are completely fictional and for illustration only but, think of the Battery as being 100% charged. An intelligent charger will sense that it's now fully charged and will stop pumping more power into it.

Now, let's say that a month has gone by and the Battery has gone flat, so you put it on the charger and it eventually reaches the point where the charger can't squirt any more power in so it stops charging. The charger thinks it's at 100% but because of the damage and loss of capacity, it's actually only 95%. If it goes flat again it may only accept 90% charge; after that it may only take 80% and so on, until the Battery needs to be replaced.

But rest assured, no harm will come from the jump start Battery pack itself.

[Heuer]

Your mistake seems to be you sat in the car without pressing 'start' ala Ready mode. You must always do that so the screens light up, the radio comes on as does the a/c - and crucially the traction Battery is connected to the 12v and so charges it. Whenever the car is unlocked make sure you get it into Ready mode. If you are in doubt about the state of the 12v Battery leave the car in Ready mode for an hour or so (the engine will start a few times) and the 12v will be charged to capacity.