[John in OkieLand]

My new fancy dancy new Clamp On ammeter came, and today's Wx cooperated enough for me to get outside.

Here is why, those Battery Cables have to be BIG as a Horse, and the connectors have to be Cleaner than momma's kitchen

820 Amps in less than 100 Milli-Seconds... that is the Time Span of the Inrush measurement for "this meter"

 

[John in OkieLand]

guess those limp $45.00 batteries won't cut the mustard, huh?

These are brand new, Walmart EverStart 65N batteries with a Free 3 year Warranty replacement. $99.00 plus tax, or they were when I bought them a couple months ago.

 

[Oneof6]

My new fancy dancy new Clamp On ammeter came, and today's Wx cooperated enough for me to get outside.

Here is why, those Battery Cables have to be BIG as a Horse, and the connectors have to be Cleaner than momma's kitchen

820 Amps in less than 100 Milli-Seconds... that is the Time Span of the Inrush measurement for "this meter"


View attachment 187681

Great meter hold and display feature that my clamp on does not have. I want one, what brand/model is it?

 

[John in OkieLand]

It is on Amazon, but I did a Internet search and found it from the Manufacturer....

at the time I located it, I had 45 minutes to buy it at $44.99
and I jumped on it....

I have since compared it to another one that I own but only goes to 20 amps....
both of them Agree to within 1 or 2 Milli-Amps in that range.

KAIWEETS HT208D Inrush Clamp Meter T-RMS 6000 Counts for AC/DC


I would do a Google Search for this model number and you can find vendors offering it for sale at prices all over the place....

 

[Oneof6]

It is on Amazon, but I did a Internet search and found it from the Manufacturer....

at the time I located it, I had 45 minutes to buy it at $44.99
and I jumped on it....

I have since compared it to another one that I own but only goes to 20 amps....
both of them Agree to within 1 or 2 Milli-Amps in that range.

KAIWEETS HT208D Inrush Clamp Meter T-RMS 6000 Counts for AC/DC


I would do a Google Search for this model number and you can find vendors offering it for sale at prices all over the place....

Thank you!

 

[Big Horn]

My new fancy dancy new Clamp On ammeter came, and today's Wx cooperated enough for me to get outside.

Here is why, those Battery Cables have to be BIG as a Horse, and the connectors have to be Cleaner than momma's kitchen

820 Amps in less than 100 Milli-Seconds... that is the Time Span of the Inrush measurement for "this meter"


View attachment 187681

John, I guess I could Google it but in layman’s terms what is inrush? Since your quoting milli-seconds is it conductivity of the cable? (it’s efficiency) thanks!

 

[Big Horn]

I did go ahead and Google— you’re dealing with DC...... I’m aware with AC when I strike an arc with the welding machine there’s a spike in amperage, after which it smooths out to a lower current....... same idea?

 

[klhansen]

Inrush is the spike in current that happens in a motor when you first hit it with voltage and isn't turning yet. Also called locked rotor current in some motor ratings. For AC motors, it's usually around 6 times full load running current.

 

[John in OkieLand]

Inrush current:

when an Electric Motor is idle, "not turning".
the Ohm Resistance value is extremely low, nearly a Dead short. Multiple turns on the Commutator, all draw current at the Same Time...


So, the current read by the meter, will be extremely high, compared to the actual current draw after it is turning at rated RPM.
( an Effect known as Backward/Reflective Impedance. )

this does not matter if it a starter on a vehicle, or the Compressor motor on your home HVAC.
my HVAC pulls 11.5 amps AFTER it is running.
the Inrush Current, to get that Compressor running is 54 Amps...
I have an AuxGen rated at 10,000 Watts with a 50 amp circuit breaker.

that Circuit Breaker trips so fast, the AuxGen does not even know that I have turned ON the A/C to colder air.

so, for the house, I can run counter top appliances ( one at at time ),
the HVAC fan draws 1.5 amps running, 3.5 amps Inrush current,
and the heater is from Natural Gas.... so we are good to go in the Winter if the Electric Grid fails.

 

[Big Horn]

Thank you gentlemen!

 

[panhead george]

Inrush is the spike in current that happens in a motor when you first hit it with voltage and isn't turning yet. Also called locked rotor current in some motor ratings. For AC motors, it's usually around 6 times full load running current.

You are correct.

 

[Oneof6]

Inrush is the spike in current that happens in a motor when you first hit it with voltage and isn't turning yet. Also called locked rotor current in some motor ratings. For AC motors, it's usually around 6 times full load running current.

Cross the line starts produce lots of current load and heat caused by 60 Hz of high voltage current dragging through < 1 Hz of rotation. A real shock to rotor and stator. Almost 100% slip at start and locked rotor resistance, at full speed slip is load related but usually 1% or less, unless it's a synchronous motor, few are.

 

[John in OkieLand]

ran a new test today, in DC Mode, MAX mode

wonder which represents the "truth" as to how much current that starter pulls in the first 100 milli-seconds?

in AC INRUSH mode, it shows 820 on one try, and 860 on another try.

 

[Oneof6]

ran a new test today, in DC Mode, MAX mode


View attachment 187702


wonder which represents the "truth" as to how much current that starter pulls in the first 100 milli-seconds?

in AC INRUSH mode, it shows 820 on one try, and 860 on another try.

Likely a clamp meter internal computation, when in AC mode setting, of what it assumes is two-way alternating direction current flow, AC. When it is actually a one-way, DC, directional current flow.

 

[panhead george]

ran a new test today, in DC Mode, MAX mode


View attachment 187702


in AC INRUSH mode, it shows 820 on one try, and 860 on another try.

The second try would be at a slightly lower voltage

 

[Oneof6]

The second try would be at a slightly lower voltage

512 Amps? OK, 512 x 11 Volts, assuming a voltage pull down of 1 volt is 5.63 KW, 7.5 HP, a big draw on a starter, probably close to what the starter is rated for if it's an aftermarket upgrade starter like a DENSO or Powermax. Seems normal to me, or within normal ranges of expectations. That "inrush" peak hold number would vary with net cycle starter load, load which is significantly influenced + - by engine temperature.

Note .... HP correction

 

[Oneof6]

512 Amps? OK, 512 x 11 Volts, assuming a voltage pull down of 1 volt is 5.63 KW, 7.5 HP, a big draw on a starter, probably close to what the starter is rated for if it's an aftermarket upgrade starter like a DENSO or Powermax. Seems normal to me, or within normal ranges of expectations. That "inrush" peak hold number would vary with net cycle starter load, load which is significantly influenced + - by engine temperature.

Note .... HP correction

Been thinking about these numbers, they dont match up with starter specs. Even though the simple math of Amps x Volts is sound how can a starter really put out 5.6KW when even a big Denso is spec'd at 4KW.
I believe it's the meter and it's peak hold function. There is no oscillation of DC but when calculated against a period of time framework to get a "Peak Hold" there is a predictable curve in a sinusoidal shape, amplitude and time instead of amplitude and frequency.
When one takes the raw data of 512 amps and applies a typical RMS factor of .74 then calculates the resultant KW and HP it comes out closer to 4KW and factors a HP close to published specs, what one would expect from a starter like a Denso
I have come to believe that the Haiweets 208D inrush peak hold feature by-passes TRMS but in other collection modes uses a standard rolling RMS strategy.

Thoughts anyone?

 

[John in OkieLand]

the brief timespan for the high current is what is being measured,
the starter is not pulling 512 amps continuously.

after the 100 milli-second measurement has passed, the Back EMF from the starter reduces the current it pulls.

at present, I have not made a setup to monitor the current while cranking, I need an extra hand, and my daughter is working full time delivering mail, and she does not work on Sundays... or me or the post office.

 

[Oneof6]

the brief timespan for the high current is what is being measured,
the starter is not pulling 512 amps continuously.

after the 100 milli-second measurement has passed, the Back EMF from the starter reduces the current it pulls.

at present, I have not made a setup to monitor the current while cranking, I need an extra hand, and my daughter is working full time delivering mail, and she does not work on Sundays... or me or the post office.

John I agree, a brief timespan, however, it has to "record" the entire time span to know which, could be multiples, is the highest peak. Consequently that time vs amplitude curve and the " peak hold " is higher than the starter rated KW but when RMS is applied it, that peak, comes into something approaching OEM KW ratings.

 

[John in OkieLand]

I am just going to say, the cables and connectors, better damn well handle 500 amps for a short short, or that starter ain't gonna spin up vera fas...