Just to Remind you that Diesel engines require more Turning power and Use all there battery's available power (amps) to get them going. this is because there is no spark to ignite the fuel it is just say 2 litres of fuel and air compressed into the space that is thinner then your fingernail and about 3 inches across...
If you have glow plugs these will drain a large amount of power (amps) out of the battery.
some newer cars ECUs will not allow the car to start if the voltage is below 12.5volts...
think your problem might be Amps related.... That is why i have a battery powering my stuff and it is in the boot, it charges of a circuit a little like the Caravan Relay, the caravan hookup for the battery in the caravan. read up on it. it might be an idea to put a sealed lead acid battery somewhere else like I have.
Thanks for the information.
Already had the same thoughts.
But I don't think it's amp related.
Because when I turned the ignition key the startmotor took so much power that it killed every power hungry stuff in the car.
Before starting I turned down my electric window to see if the battery was empty.
The window went down but I went down as slow as a snail.
So in my non electric technical brain is saying the battery is empty.
Today I contacted my car dealer.
Now I know after contacting my Peugeot dealer that my car (308 estate) needs at least 12.5volt to start in cold weather condition.
And 12 volt in warm warm weather.
So your right when it comes to the power the engine needs to get turned on.
The idea you mentioned about getting everything powered from the boot on a separate battery sounds good.
I had the same in my youth as I was into cartuning those days.
And had all the lights and stuff powered on a gel battery in the boot. So maybe it could be my problem saver.
But then in a way like a small battery which you can find in those 50cc scooters.
This battery could be charged via the constant acc which is hooked up on my pullinghook.
Suggestion are welcome.
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