how many amps does your car starter draw?

[Matt Gruber]

QUIZ:
using a cheap DVM (like $2.99)
measure cranking amps!
report your results here.
.
the reason i checked is
i wanted to see if a marine deep cycle has enough amps to start.
Then, in an emergency, i could use the car marine DC LA to run my mbike.

 

[BrendaEM]

Marine and other deep cycle batteries usually have a little thicker plates than starter batteries, so they will last longer in deep dischare use.

Many people use Optima "yellow tops" in their full-sized electric cars. The D34m's, can give 750 cold cranking amps, and can deliver 25 amps for 2 hours. If you are not racing your EV, I would avoid all starter batteries.

http://endless-sphere.com/forums/viewtopic.php?t=470

 

[Ypedal]

And how exactly do you plan to check amp draw into the 100's with a small DVM ? Mine will only allow 10 amps.

 

[Matt Gruber]

And how exactly do you plan to check amp draw into the 100's with a small DVM ? Mine will only allow 10 amps.

QUIZ IN PROGRESS
http://forums.corvetteforum.com/showthread.php?t=1657219

 

[Toorbough ULL-Zeveigh]

And how exactly do you plan to check amp draw into the 100's with a small DVM ? Mine will only allow 10 amps.

Would this add-on do the trick?

http://www.obd2.com/accessories/data/currentclamp.htm



These current clamps will allow your multimeter to measure AC and DC electronic current up to 60 or 600 amperes, depending upon the model purchased. Both models have two shielded banana plugs that plug into the jacks of the multimeter. (The multimeter must have a minimum input impedance of 10k ohms).






Z-PDI-CA-600 Current Clamp

AC/DC Current Clamp 0 - 600A

This current clamp will allow your multimeter to measure electronic current up to 600 amperes AC/DC with a frequency response up to 400 Hz. When measuring current with this clamp, there is no need to break a circuit.

Features:

Measures 0 - 600 A AC/DC current

Current Clamp Accuracy: +/- 2% to +/- 6% plus 2A

Frequency Response: 50 - 400 Hz

Maximum Working Voltage: 480 VAC / 600 VDC

Load Resistance: 10 k ohms

Uses 9 V DC battery - one is included with unit

Manufacturer limited 2 year warranty

Part # Price
Z-PDI-CA-600 $109.00

 

[TylerDurden]

Another:

http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_200320843_200320843

High accuracy and resolution
One touch “Auto Zeroâ€￾
Large 4000 count LCD
40A and 400A ranges with 0.01A resolution and 3.5% basic accuracy
Easy to use, single function meter
Auto power off saves battery life
Overload protection
Data hold freezes reading on display
Large 1.2in. clamp jaw opening
CE certified
CATII-600V rating
9 Volt battery included
Protective rubber holster
Wrist strap
Belt holster
1-year limited warranty
Model DC400

 

[Matt Gruber]

Tyler
thanks but no,
nothing else is needed.
(of course they would work)

 

[fechter]

Just measure the voltage drop on the negative battery wire (since the headlight current and the starter current both go through this piece of wire) between the battery and the place on the frame where it attaches.

Turn on the headlights and make a measurement.

Turn off the headlights.

Run the starter and make a measurement.

The current draw of the starter will be the amp draw of the headlights times the ratio of the two measurements.

How do you measure the draw of the headlights?

 

[TylerDurden]

OK, I peeked... but to make sure I understand:

the ratio of the headlight current to voltage drop is equal to the ratio of the starter current to its voltage drop?

 

[v_tach]

You could rig a shunt to measure the current loss with a DVM. Used to do it with a common 1 ohm wire wound resistor for applications less that 1 amp. Not sure what you'd need for something like a vehicle starter.

 

[fechter]

OK, I peeked... but to make sure I understand:

the ratio of the headlight current to voltage drop is equal to the ratio of the starter current to its voltage drop?

Right. The resistance stays the same. Ohm's law.

Depending on the resistance of the wire and the sensitivity of the meter, the readings might be near the limit of resolution for the meter, making the measurement a bit crude, but it will be in the ballpark.

 

[Matt Gruber]

You could rig a shunt to measure the current loss with a DVM. Not sure what you'd need for something like a vehicle starter.

Yes!
i use the heavy ground cable as the shunt. nothing to buy.

 

[Matt Gruber]

Just measure the voltage drop on the negative battery wire (since the headlight current and the starter current both go through this piece of wire) between the battery and the place on the frame where it attaches.

Turn on the headlights and make a measurement.

Turn off the headlights.

Run the starter and make a measurement.

The current draw of the starter will be the amp draw of the headlights times the ratio of the two measurements.

How do you measure the draw of the headlights?

i couldn't say it better myself!

The $2.99 DVM's i use all have a 10 amp shunt built in, read to 20a. Just dis the ground cable and put the DVM in series to read the lights for amps. That's a very accurate baseline (but stay under 15a if possible, 16ga wire leads will heat up)

Thanks guys! Now i'll check my 72

 

[Matt Gruber]

test took 3 minutes!
lights 13.6a at 19mv
starter 240mv
amps therefore are 172.
remember i ran a battery AA top to start it?
i was way off thinking it drew 350! LOL
pays to do a real test.

$2.99 DVM tells the truth!

 

[Matt Gruber]

The ordinary Exide deep cycle size24 is my top pick. a whopping 80AH, and 140 minutes RC at 25a(about 5 hours @12a 17mph or 85 miles range!). yet still cranks at 500a 32F. Way beyond my needs and lots cheaper than the Optima which has 120min 750ca
.
But i can find no specs on the Wal mart one, so i'll have to buy it and test it.

 

[Matt Gruber]

tested my 61
Very hard to find a good ground.
Best was bumper.
Highbeams 11.3a, 21mv drop
no gas crank 290mv
290/21= 13.8, 13.8x11.3= 156a
but get this
hit the gas, got the rip rip rip sound from a high compression engine with aggressive spark advance
mv flashed up to 564!
564/21x11.3= 303 amps!
started right up.
moral: there is cranking amps and starting amps and they are not the same!

 

[Doctorbass]

I personally added a 300A shunt in series with the negative terminal of my 12V batery on my Acura integra SE 2000 (i often participate to SPL contest and use huge amplifier like 6500W rms (700A at 12V +6V)

I measured around 240 to 300A peak during start at summer time

if that could give you an idea.. my shut was a 300A 50mV used on fluke 179DVM