PD Motor Power Consumption

Last night, as I watched on the highway, one electrical system after another being shut down, I wondered how long it would take for my engine's electronics to fail. Unfortunately, I got my answer sooner than I hoped. This morning, after only a short time with a jump cable and a donor battery, the car managed to drive the last 5 kilometers on its own power.
"Now I'm wondering how much power a PD motor consumes, and how far it would travel on a full battery if the alternator completely failed. I've already driven almost 200km. Does anyone have more information about this?"

mcgyver2k wrote:

Now I'm wondering how high the power consumption of such a PD motor is, and how far it would travel on a full battery in case of a complete failure of the alternator. I've already driven almost 200 km before. Does anyone know more about that?

"In my opinion, the biggest energy consumers are likely the open power windows. Therefore, driving in a way that maximizes fuel efficiency will probably allow you to travel the furthest distance."

The engine control unit in the Polo is protected by a 30A fuse, while the pre-lift pump is protected by a 15A fuse.
However, in operation, it only draws about 4 amps, which is roughly 1/3 of the fuse rating.
If we apply this ratio to the EDC, we get approximately 10 amps, plus the pre-charge pump, which adds up to about 14 amps.

In addition to the above, we can expect at least (and it's unavoidable) the AI system and the vehicle's body control module (BCM) to draw around 20 amps during operation.

With a fully charged battery, you could theoretically drive for approximately 3 hours...

However, this is only a speculated estimate and not a confirmed value! Whoever knows it more reliably is correct.

...which means that at night, at least another ~13 amps were likely used for the lights throughout the area.

A fault in the alternator doesn't necessarily mean that it will produce zero current; it could also simply produce less current. Conversely, it's also possible that the alternator could even draw current *from* the battery. Therefore, depending on the specific defect, it's very difficult to predict how long the battery will last. Moreover, the battery will almost never be fully charged.

Hi there.
It has nothing to do with the question, but I just have to get this off my chest...
Okay, my old Golf II with a small block engine, I think, consumes about 6 watts per hour (for the parking light). With a 60Ah battery, I can drive for about 80 hours until it is 2/3 empty .
And if you tweak the fuel cutoff setting, it will run until there's no fuel left .
Well, not everything modern only has advantages...

Regards,
Jens.

Quote:

6 W per hour

I can't just let that stand like that, as an "insider."
What is a time-independent quantity? That is, something without a "per hour" unit.

wolfi_b wrote:

Quote: 6 W per hour I can't just let that stand like that, as an "insider." What is a time-independent quantity? That is, something without a "per hour" unit

.

Hi Wolfi,

Jens' statement is already quite accurate. While it's true that the power rating (Watt) doesn't have a time component, his calculation is about the total amount of energy until the battery is almost empty.

Best regards, Rainer.

Watt = Joule/second and has a time component. Watt per hour is redundant, as it describes a change in power over time.

The problem I had was that the cable, which was supposed to carry the excitation current to the alternator, was severely corroded and therefore barely supplying any current.

The good old 1017s used by the Bundeswehr didn't need any electricity. As long as there was enough air in the boiler in the morning, you could push them and they would run fine. Lights and such are unnecessary in the field anyway.

Hi,

Watt-minutes are a measure of energy, which is useful (after all, electricity is billed in kilowatt-hours), but W/s is not very meaningful.

Best regards,

Jan.

You guys at OHM, just do what you VOLT !

So, the correct formula for work is: Work = Force x Distance

You guys at OHM, just do what you VOLT !

So, the correct formula is: Work = Power x Time .


hehehe...

Consequently, power is defined as work done per unit of time.

den MAL ZEIT is LUNCH BREAK

'That's what my trainer used to say...'

Just clamp an ammeter onto the appropriate wires...


CU Gremlin.

You guys at OHM, just do what you VOLT !

So, the correct formula for work is: Work = Force x Distance .


hehehe...

Consequently, power is defined as work done per unit of time.

den MAL ZEIT is LUNCH BREAK

'That's what my trainer used to say...'

Just clamp an ammeter onto the appropriate wires...


CU Gremlin

Hi,
'I'd like to see the measurement result from the clamp meter. Due to the magnetic coupling, DC current cannot be measured with such a device. In the case of the alternator, there's an superimposed AC component because the alternator doesn't produce a smoothed DC current due to the lack of electrolytic capacitors. And because it's a three-phase alternator, the current never actually reaches zero, as the next half-wave arrives before that. So, a clamp ammeter will certainly show something, but it won't be what's actually flowing.'

So, what's the voltage, the current, and the power?

Greetings.

Eike.

So, a clamp ammeter will certainly show something, but not what is actually flowing.


That definitely doesn't come from Obi.

a vernünftiges® already... it also shows you the currents in the 3+N cable, WITHOUT you having to disconnect the wires .

CU Gremlin.

Yes, measuring DC current with pliers is generally not a problem. For example, with a Hioki http://www.hiokiusa.com/modules/products/index.php?op=viewproduct&proid=45, it is possible.

Assuming that a measurement range of 2 kA is sufficient .

Quote:

6 W per hour

Hargl... I overlooked the pro, shame on me...

That's certainly stirred things up .

mcgyver2k wrote:

Watt = Joule/second and has a time reference.

Yes, I understand, I expressed myself incorrectly .

And I thought I had strayed far from the topic .
What were we talking about again?

Regards,
Jens.