Battery current during engine start

[Salvo]

I was a bit curious how much current is pulled during my 5-cylinder diesel start. It's more than I thought.



Just before the 8 sec mark the ignition is turned on. The glow plugs pull over 100A.

After 12 sec the engine is cranked. Current spikes to over 700A. It takes about 1 sec to start. After ignition, glow plug current settles to about 90A.

At 16.5 sec the alternator kicks in. Battery current ramps (negative) to about 20A. The battery is now charging. Negative current is charging current.

[wa8yxm]

That chart looks... Very reasonable.

[brulaz]

Guess there's a reason many diesel trucks have 2 starting batteries in parallel.

[SCVJeff]

Salvo wrote:
I'm using a current clamp (Hantek CC-650). The Hantek has an analog output which is connected to a 16-bit A/D. The A/D connects to an Arduino datalogger. Data is recorded at 1.5 ms rate.

What is EMF?

The field collapsing on the starter solenoid. Or.. That which knocks you on your pattutie if you have a hand on the coil.

We were trying to measure starting current on a QD7500 without removing fuel lines. We looked at two and there is a 100A difference between them but we think it's just bad sampling.

[tatest]

That 700 is a spike fed by surface charge on the battery plates. Internal resistance in most lead-acid starting batteries limits deliverable current to 400 amps or less. NiMH could deliver more.

[NinerBikes]

Good stuff, any idea what the compression ratio is on that 5 banger? Miles on the odometer, and how well it's now broken in, or not?

[landyacht318]

Sweet graph, Thanks.

I've looked at my digital ammeter when cranking a gas engine,and see it go as high as 140 amps cold and 75 amps hot.

Do not know how much it would spike too if the refresh rate of the ammeter was higher

[pianotuna]

Great graph, Thanks for taking the time to post it.

[Salvo]

I'm using a current clamp (Hantek CC-650). The Hantek has an analog output which is connected to a 16-bit A/D. The A/D connects to an Arduino datalogger. Data is recorded at 1.5 ms rate.

What is EMF?

[SCVJeff]

Nice! I assume the 100A are the heater/ glo-plugs, and the little rise after start is starter EMF releasing?

Got a QuietDiesel 7500 anywhere to look at?
My Dranetz is somewhere on the East coast and I don't think it does DC either