Carsy

Below are a few figures taken from my cars log.

I am interested to know why there is a 33 amp load on the system after startup? this load decreases over about 15 minutes of driving to under 6 amps.

Before starting ,key in first position :-Volts 12.1, Amps 33

Whilst starting :-volts around 10, amps 102.The starter draws a lot which is normal.

Idling:- Volts 14, Amps 33 & reducing to 13 amps over about 3 minutes.
After 15 minutes whilst driving :- amps were 5.9.


I must say I am surprised of the high 33 amp load with just the key in the ignition .

Why does the load slowly decline from 33 to 6 odd amps over 15 minutes?

Any auto electrical specialists out there ?

Rayvan

That's your battery being charged back up. Takes lots of electrical power to start up a diesel!

Carsy

Good thinking .

Interesting that there is 33 amps load when the key is in the first position before start up & the fact it takes only 15 minutes of running to replenish battery after startup.

Rayvan

I'm guessing, but the 33 amps when the key is in the first position may be glow plugs. That's how my sister's VW diesel works, not sure about yours...

Ausmbtech

Thats all the control units going through their initial start up that draws all that power when the key gets turned. I did a test once on an early W211 and it could draw 30+amps just hitting the unlock button on the key before you even opened a door.

Batteries are more important on current vehicles then ever before. I'm starting to hear of some very random electrical faults on Audi's and BMW's being traced back to a poor quality but good condition (usually less than 6 months old) battery and nothing else.

25A battery chargers were considered powerful when I started in the trade, 100-120A chargers are becoming common in dealers due to the high power consumption whilst programming control units.

rapidoxidation

Glow, start, afterglow, recharge the battery. It all takes juice.

kurtismayfield

Does your diesel have an electric heater? My 'e' class does. It supplements the cabin heat until the coolant reaches normal operating temp.


Glow plugs don't activate until the second ignition position.


Hope this helps you.
Kurtis

Carsy

I receive heat after about half a mile running so it may be possible there is a heater . Thanks Kurtis.