[Daviebrown]

You are putting for too much focus on the battery voltage when the deviation is less than 1Volt, you left the doors open for two hours with the interior lights on and the battery went flat, try the same again with the different battery and if it's okay buy a new battery and if the car starts every morning stop looking at the voltmeter.

[Tambohamilton]

Are all 3 of those voltage measurements taken with a multimeter at the battery?

[MrSweet1991]

Originally Posted by Daviebrown

You are putting for too much focus on the battery voltage when the deviation is less than 1Volt, you left the doors open for two hours with the interior lights on and the battery went flat, try the same again with the different battery and if it's okay buy a new battery and if the car starts every morning stop looking at the voltmeter.

The first time when I was doing the reverse camera I would definitely say that was more than likely the cause, but a few days ago I possibly left the car unlocked while I was helping a friend and when I came back to the car it showed 11.4v on the xtrons which can be off by maybe point 2 or 3 of a volt but the car didn't even crank over. On some mornings it would take maybe 2 or 3 times to try and start and as early as the second attempt it was already slowing the cranking speed and I've had to jump the car on a few occasions.. Though I have to say it really is random.

I've borrowed the battery until the morning so I'll see how it goes.

[Tambohamilton]

Have you checked the earth strap in the engine bay, and all other big connections? Also, when it doesn't crank over, does it try but not have the power, or does literally nothing happen?

[MrSweet1991]

Originally Posted by Tambohamilton

Are all 3 of those voltage measurements taken with a multimeter at the battery?

All three at the battery, interestingly though, despite that monster draw the battery did slowly get back to 12.5x volts once asleep. I was actually looking at another forum and a chap noticed something similar to me, on ignition on you could literally watch the voltage drop rapidly, I don't think the solution was posted but they seemed to Sway towards the possibility of grounding/short circuit issues that would occur when the ignition was turned on causing a huge power draw.

I had a look back at my videos and the car wasn't running when I was watching the film in the car.. Annoyingly though the voltage isn't shown on the xtrons while watching something, i would have been interested to know as it was clearly doing okay back then.

[MrSweet1991]

Originally Posted by Tambohamilton

Have you checked the earth strap in the engine bay, and all other big connections? Also, when it doesn't crank over, does it try but not have the power, or does literally nothing happen?

Good point. I will check the earth strap and the other ground connections. Though I always wondered if it was something like a ground strap would it be logical for a lower voltage but once jump started it would be perfectly fine again for days/weeks..

The cranking is definitely low voltage, I've never had a situation where it would instantly click, I could maybe get a couple of cranks before the ABS DTC and all the rest show.

[Andystobbs]

Battery will show lower voltage under load, thats voltage drop, which will recover on a healthy battery.
Check the cleanliness of the two wires passing through the battery box at the back of the car. They always seem to be dirty and probably offering additional resistance.

As said by Tambo, Earth strap in engine bay, they do fall apart. That would only pose a high resistance during cranking or charging though.

I've never actually checked the time but I'm sure my car turns the interior lights off after so long. The relay on terminal 30g is used to shut down electrical consumers.

[MrSweet1991]

Originally Posted by Andystobbs

Battery will show lower voltage under load, thats voltage drop, which will recover on a healthy battery.
Check the cleanliness of the two wires passing through the battery box at the back of the car. They always seem to be dirty and probably offering additional resistance.

As said by Tambo, Earth strap in engine bay, they do fall apart. That would only pose a high resistance during cranking or charging though.

I've never actually checked the time but I'm sure my car turns the interior lights off after so long. The relay on terminal 30g is used to shut down electrical consumers.

Hi Andy,

Dropped the Bosch back to the chap, checked mine with a multimeter before I hooked it back up and it maintained a full charge of just over 12.6v. Drove as per usual, locked the car and by morning I just wanted to see what voltage the xtrons read and it said 11.4v (give or take 0.2 +/-) and literally one single crank and lights dimmed. So.. As far as I'm aware we tested for parasitic draw and I couldn't see anything drastic on the Multimeter so I had a quick look and I've seen a few posts state the AGM batteries are quite beneficial even of you don't have stop start, Ive bought a Bosch S5 A13 AGM with 5 years warranty. It won't come till Tuesday and I'll make sure I code the car to AGM as I believe AGM's charge 4x faster than acid batteries, the alternator is in great shape as it was replaced about a year ago or less with a brand new Lucas.

I'm hoping that sorts the issues out, in the meantime I've been working on reducing those faults. I've had a window regulator come, I bought a pin connector removal kit to sort the LED number plate light (it seems to have a weak connection at the pins in the connector) I've got some brushes to repair the Aux water pump and I'll jack the front up and have a look at the oil condition/level sensor which is located on the bottom of the sump.. Just to help clear up some potential shorts which you mentioned as a possibility a few posts back. I'll also have a look at the ground strap condition.

[MrSweet1991]

Yesterday, left car unlocked and came back to it maybe 4 hours later, voltage showed like 9 point something volts. Jump started using an old battery and been perfectly fine, this morning had 11.8v.. Very strange. Got the Bosch AGM coming later