AMPAGE TESTING (12 Volt DC)

[srands]

Useful reference guide for AMPAGE TESTING of 12 Volt DC.



PICTURE VERSION URL:
https://blufiles.storage.live.com/y...znmbCQXpJVytYH2xzFs/AmpageTesting12VoltDC.jpg

WORD VERSION URL:
https://skydrive.live.com/view.aspx?cid=9EC5688DD90EEC6C&resid=9EC5688DD90EEC6C!581

TOOLS NEEDS:
MULTIMETER, SCREWDRIVERS & BLOCK CONNECTORS

This is quite simple see following pictures (Much easier to do then first impression on reading instructions), the MultiMeter in this instance (DRAWN, POSITIVE TERMINAL) tests the AMPAGE between the POSITIVE SUPPLY (red probe lead) and the POSITIVE LOAD (black probe lead). Hence the NEGATIVE is uninterrupted from SUPPLY to LOAD (In other words, leave it alone). In this instance the positive supply has croc clips, normally I'd use insulated BLOCK CONNECTORS:
PIC1 (multimeter measuring AMPAGE between POSITIVE supply & POSITIVE load)

PIC2 (12V dc Battery Charger powering car cd player, with MultiMeter Testing AMPAGE)

PIC3 (CAR CD PLAYER in house install powered by CAR BATTERY CHARGER 12 V dc 4A)

PRECAUTIONARY NOTEs:
~ Obviously the NEGATIVE and POSITIVE can NOT touch each other (Neither SUPPLY or LOAD)
~ If your MultiMeter has NEGATIVE READING, then means you have your PROBE LEADS the wrong way (Or just ignore the negative symbol, as the AMPAGE figure will be accurate).
~ The 12V dc MOTOR/PART or ALTERNATOR/SOLAR PANEL may CHARGE/DRAW a greater AMPAGE/CURRENT then the capacity of the MULTIMETER & its LEADS (At this point the actual ampage is unknown). For example most car electrical parts are low current (Indicators, elec windows, elec sunroof, heater, etc), with the obvious exception of a car starter motor (Extremely high ampage/current, totally unsuitable for testing with MultiMeter). Hence if the 12V dc part/motor or the charge rate of the power supply is greater then 10A this may melt your MultiMeter probe leads and/or break the MultiMeter (Unless you have a 20A DC MultiMeter! Obviously the ampage max of those is 20A DC).

OTHER NOTES:

~ The AMPAGE reading given by your MULTIMETER, is given by testing 'A' POSITIVE or 'A' NEGATIVE, however the AMPAGE reading is the total AMPAGE drawn/charged, so this figure should NOT be doubled in your calculations.

~ If you're testing direct from a car battery and it's loom, it may have other parts/motors draining ampage, such as indicators/wipers, etc. So turn ON the ignition (WITHOUT STARTING THE CAR, as the ampage drain would be far too great for the MULTIMETER & PROBE LEADS!), then make a note of what the standard ampage drain is approximately (i), then turn on the motor/device/appliance you want to test (ii). Then subtract the standard ampage drain from the new figure with the appliance/device/motor on to EQUAL the difference (iii) i.e. The ampage of the motor/part etc.
FOR EXAMPLE:
i) STANDARD AMPAGE DRAIN = 0.5a (Car alarm or something else)
ii) STANDARD AMPAGE DRAIN & OTHER MOTOR = 1.5a
iii) CALC 1.5a - 0.5a = 1.0a

Alternatively (my preferred practice/method) connect new leads to the battery terminals, so there won't be any other registered ampage drawn from the car battery. So the ampage reading is what it is!
PS. Don't mess about from behind the car fusebox, keep it simple, either direct from car battery and loom OR new power leads from car battery to motor/part/device/appliance your testing with a MULTIMETER.

I made this guide as a quick reference when testing 12 Volt DC circuits with a MultiMeter, EITHER:
~ ampage CHARGE to batteries
OR
~ ampage DRAWN from batteries.The main reason for this guide is that I was not impressed (And continue to be not impressed with the lack of meaningful instructions) with uncomprehensive manuals supplied with most MultiMeters. Seems odd to make a great feature but don't explain in the instructions.

Remember most MultiMeters (£10 Maplin job ok) only test upto 10A 12V DC, more expensive MultiMeters (UNI-T from Maplin £30 why spend any more) test upto 20A 12V DC.

ALTERNATIVELY To test AMPAGE of 240 VOLT APPLIANCES use a plug in ENERGY MONITOR (From Maplin).

This guide I'm sure will be a great help to test 12 Volt DC circuits, however please feel free to add these links below (Website addresses, urls, etc), the numerous number of posts on this subject (That I couldn't find), and web references to wiring regulations, and any other derogatory negative remarks you have as well!

CHEERS, AND BELOW IS A FULL LIST OF MY OTHER USEFUL GUIDES & SPREADSHEETS (Top entries of electrical interest)

STEPHAN RANDS
AMPAGE TESTING (12 Volt DC)
RING AMP AUTOCALC: 1ST TAB
LIGHTING CIRCUITS, RING & RADIAL wiring diagrams
UTILITY ENERGY MEGACALC
MPG
METRIC AUTOCALC
PERCENTAGE CALCULATOR AUTOCALC
EXCEL USEFUL FORMULAS
MTB ROUTES IN/NEAR HULL, HUMBERSIDE
TIER 4+ CATEGORY TYPE
TIER 4+ MONEY TYPE
AUTOCALC WEBSITE

 

[MarkieSparkie]

Oh dear! Not again! Another of your perverse creations, a solution looking for a problem. For somebody who wishes to provide electrical information for the ordinary person you have a unique, blinkered way of going about it. You can't even get the terminology correct, despite earlier advice on this forum by various members. Far from achieving your object, most of it's over complicated, ill-informed pseudo-science and sophistry. Why you wish to post such tat on this forum escapes me, maybe it gets you some extra hits on your website by association. It is extremely unlikely that you will get support and good revues for your work from intelligent electricians on the evidence presented to date. We have better things to do with our time, like helping those that have genuine problems or who wish to learn from us. You do not appear to fit in to either category. I suspect you post just to blatantly publicise your website and views.

 

[malcolmsanford]

Be honest though there is not a socket wire in sight.

 

[Geordie Spark]

Oh dear! Not again! Another of your perverse creations, a solution looking for a problem. For somebody who wishes to provide electrical information for the ordinary person you have a unique, blinkered way of going about it. You can't even get the terminology correct, despite earlier advice on this forum by various members. Far from achieving your object, most of it's over complicated, ill-informed pseudo-science and sophistry. Why you wish to post such tat on this forum escapes me, maybe it gets you some extra hits on your website by association. It is extremely unlikely that you will get support and good revues for your work from intelligent electricians on the evidence presented to date. We have better things to do with our time, like helping those that have genuine problems or who wish to learn from us. You do not appear to fit in to either category. I suspect you post just to blatantly publicise your website and views.

Or, in another word ...... SPAM !! :dead:

 

[Des 56]

quote
Useful reference guide for AMPAGE TESTING of 12 Volt DC.

Here you go again
I only got as far as line one,but if you insist on referring to the long word for amp,then at least give the guy Ampere some credit and refer to it as amperage not ampage

This is ampage Flash Intro Page

 

[Knobhead]

Ampage is a NON word, check the OED

 

[srands]

Oh dear! Not again! Another of your perverse creations, a solution looking for a problem. For somebody who wishes to provide electrical information for the ordinary person you have a unique, blinkered way of going about it. You can't even get the terminology correct, despite earlier advice on this forum by various members. Far from achieving your object, most of it's over complicated, ill-informed pseudo-science and sophistry. Why you wish to post such tat on this forum escapes me, maybe it gets you some extra hits on your website by association. It is extremely unlikely that you will get support and good revues for your work from intelligent electricians on the evidence presented to date. We have better things to do with our time, like helping those that have genuine problems or who wish to learn from us. You do not appear to fit in to either category. I suspect you post just to blatantly publicise your website and views.

It's simple knowledge, in 12 Volts DC there is no other way. Don't be so negative.

MATE elec is simple, chit chat here is just to confuse novices looking for basic knowledge.
240v ac to find out appliance AMPAGE or WATTs, look at the back of the appliance, look in the manual, or browse the internet. If it doesn't mention AMPAGE or WATTs anywhere (The fuse size may not be a good indication), then use a PLUG IN ENERGY MONITOR (Because there is no other instant alternative, OR use an elec meter just for the sole purpose of testing for power consumption in WATTS/AMPs).


12v dc to find out the AMPAGE or WATTs of a device/motor (Car cd player, car sound amplifier, portable dvd player, etc) look at the back of the device, look in the manual, or browse the internet. However it is more then likely it won't mention AMPAGE or WATTs anywhere (The fuse size may not be a good indication), hence you a MULTIMETER as given in the instructions of the 1st post.
Also a car elec is from a 12Volt car battery hence supply is direct from the battery terminals, or alternatively from the car's CIG LIGHTER SOCKET (If it has 1), since device manufacturers don't make a 12V dc Energy Monitor that plugs into the car cig lighter socket, there is no other alternative to find out the 12V dc AMPAGE of a motor/part.
To calculate correct FUSE from appliance WATTS:
W = Watts, V = Voltage, A = Amps
W / V = A Eg 1200Ws / 240v = 5A

To calculate WATTS max for circuit:
A x V = W Eg 32A x 240V = 7680Ws = 7.68KWs
1000 W’s= 1 KiloWatt (Used on elec meters)

It is that simple, all other chat is just to deliberately confuse, under the false pretenses of thinking they wouldn't be able to do it.

 

[srands]

Be honest though there is not a socket wire in sight.

Also a car elec is from a 12Volt car battery hence supply is direct from the battery terminals, or alternatively from the car's CIG LIGHTER SOCKET (If it has 1), since device manufacturers don't make a 12V dc Energy Monitor that plugs into the car cig lighter socket, there is no other alternative to find out the 12V dc AMPAGE of a motor/part.

 

[srands]

quote
Useful reference guide for AMPAGE TESTING of 12 Volt DC.

Here you go again
I only got as far as line one,but if you insist on referring to the long word for amp,then at least give the guy Ampere some credit and refer to it as amperage not ampage

This is ampage Flash Intro Page

MATE in 12V or car speak, the abbreviation AMP to most people means AMPLIFIER, hence why I used the WORD "AMPAGE" instead of AMP, no auto electrician sayes "AMPERE" or "AMPERAGE", they say AMPAGE or AMP, but to car drivers, they would/may/might confuse this with car AMPLIFIERS. Hence they'd get confused about power watts and sound watts, hence the substituted full word AMPAGE, instead of AMP(s).

 

[trev]

Amperage

 

[Geordie Spark]

I used to wonder what a masochist was but now that I know I'm now left wondering if the masochist here is the OP for returning here to post yet again, or me for reading the post !!!

 

[Geordie Spark]

MATE in 12V or car speak, the abbreviation AMP to most people means AMPLIFIER, hence why I used the WORD "AMPAGE" instead of AMP, no auto electrician sayes "AMPERE" or "AMPERAGE", they say AMPAGE or AMP, but to car drivers, they would/may/might confuse this with car AMPLIFIERS. Hence they'd get confused about power watts and sound watts, hence the substituted full word AMPAGE, instead of AMP(s).

That's all well & good ............ or it would be IF this was a car forum, but it isn't !!!!

 

[srands]

That's all well & good ............ or it would be IF this was a car forum, but it isn't !!!!

Yer well not all 240V ac electricians know about 12V dc, and besides this forum isn't called ELECTRICIANS FORUM (Not Auto or 12V dc, just 240V ac), is it, no!

 

[Des 56]

MATE in 12V or car speak, the abbreviation AMP to most people means AMPLIFIER, hence why I used the WORD "AMPAGE" instead of AMP, no auto electrician sayes "AMPERE" or "AMPERAGE", they say AMPAGE or AMP, but to car drivers, they would/may/might confuse this with car AMPLIFIERS. Hence they'd get confused about power watts and sound watts, hence the substituted full word AMPAGE, instead of AMP(s).

Unusually, this an explanation (to something that you posted) that can be described as reasonable ,even if not agreeable,so thanks for that

 

[srands]

Here is the LONG version (After reading the 1st post SHORT version, thought I'd beef it up with some more data, details, etc):



PICTURE VERSION: WORD VERSION:
TOOLS NEEDS: MULTIMETER, SCREWDRIVERS & BLOCK CONNECTORS

This is quite simple see following pictures, the MultiMeter in this instance (DRAWN, POSITIVE TERMINAL) tests the AMPAGE between the POSITIVE SUPPLY (red probe lead) and the POSITIVE LOAD (black probe lead), this is known as breaking the circuit. Hence the NEGATIVE is uninterrupted from SUPPLY to LOAD (In other words, leave it alone). In this instance the positive supply has croc clips, normally I'd use insulated BLOCK CONNECTORS:

PIC1 (multimeter measuring AMPAGE between POSITIVE supply & POSITIVE load)


PIC2 (12V dc Battery Charger powering car cd player, with MultiMeter Testing AMPAGE)


PIC3 (CAR CD PLAYER in house install powered by CAR BATTERY CHARGER 12 V dc 4A)


PRECAUTIONARY NOTEs:
~ Obviously the NEGATIVE and POSITIVE can NOT touch each other (Neither SUPPLY or LOAD)
~ If your MultiMeter has NEGATIVE READING, your PROBE LEADS are the wrong way (Or ignore negative symbol, as AMPAGE figure is accurate).
~ The 12V dc MOTOR/PART or ALTERNATOR/SOLAR PANEL may CHARGE/DRAW a greater AMPAGE/CURRENT then the capacity of MULTIMETER & its LEADS (At this point the actual ampage is unknown). Eg: Most car electrical parts are low current (Indicators, elec windows, elec sunroof, heater, etc), with the obvious exception of a car starter motor (Extremely high ampage/current, totally unsuitable for testing with MultiMeter). Hence if 12V dc part/motor or charge rate of power supply is greater then 10A this may melt your MultiMeter probe leads and/or break the MultiMeter (Unless you have a 20A DC MultiMeter! Obviously the ampage max of those is 20A DC).

OTHER NOTES:
~ The AMPAGE reading of your MULTIMETER, is given by testing 'A' POSITIVE or 'A' NEGATIVE, however the AMPAGE reading is total AMPAGE drawn/charged, so this figure should NOT be doubled in your calculations.

~ My preferred practice/method, & the MOST accurate, is to connect new leads to the battery terminals, so there won't be any other registered ampage drawn from the car battery. So the ampage reading is what it is! (PS. Don't mess about from behind the car fusebox, keep it simple, either direct from car battery and loom OR new power leads from car battery to motor/part/device/appliance your testing with a MULTIMETER.)

~ Alternatively (The least preferred, & least accurate) If you're testing direct from a car battery and it's loom, it may have other parts/motors draining ampage, such as indicators/wipers, etc. So turn ON the ignition (WITHOUT STARTING THE CAR, as the ampage drain would be far too great for the MULTIMETER & PROBE LEADS!), then make a note of what the standard ampage drain is approximately (i), then turn on the motor/device/appliance you want to test (ii). Then subtract the standard ampage drain from the new figure with the appliance/device/motor on to EQUAL the difference (iii) i.e. The ampage of the motor/part etc.


FOR EXAMPLE:
i) STANDARD AMPAGE DRAIN = 0.5a (Car alarm or something else)
ii) STANDARD AMPAGE DRAIN & OTHER MOTOR = 1.5a
iii) CALC 1.5a - 0.5a = 1.0a

This guide is a quick reference when testing 12 Volt DC circuits with a MultiMeter, EITHER: ~ ampage CHARGE to batteries OR ~ ampage DRAWN from batteries.

Why test for AMPAGE? To determine what cable/lead thickness to use, and bigger is always better (Future proof, as you may add more devices to that circuit load). See rough guide below for 12v dc twisted wire (Not Socket wire):

CABLE SPECIFICATIONS for DC 12 Volts
THICKNESS (Either ~ Individual insulated wire thickness in mm APPROXIMATE)	AMPAGE (max of cable/lead/wire)	WATTAGE (max of cable/lead/wire)
2.7mm	3A	36w
3.0mm	10A	120w
3.8mm	20A	240w
5.0mm	35A	420w
6.2mm	50A	600w
1.2CM	AWG8 / 40A	480w
1.6CM	AWG4 / 70A	840w

To calculate correct CABLE/WIRE/LEAD thickness (Or FUSE Ampage) from appliance WATTS:
W = Watts, V = Voltage, A = Amps
W / V = A Eg 10Ws / 12v = 0.8A

Remember this isn’t exact, bigger is always better, thicker cable have less wear & tear overtime, & generally in 12v dc, thinner cable is also inadequate, because the motor/part/device can NOT draw sufficient current from thinner cable.
Here are some good examples, whenever I fit car sound amplifiers, OR large inverters into cars I use AWG8 which has an ampage of 40A, which is far greater ampage then the car sound amplifier or inverters, such as:
~ 40A / 4A (Ampage of an large inverter) = cable 10 times the ampage of the inverter
~ 40A / 20A (Ampage of a 4 channel 400 Watt car sound amplifier) = cable 2 times the ampage of the inverter
Hence fitting much larger ampage cable, then the actual ampage of the device (car sound amplifier or inverter) is common good practice.
To calculate power WATTS max for circuit (If the rest of your system is specified in 12V Watts rather then 12V Ampage):
W = Watts, V = Voltage, A = Amps
A x V = W Eg 20A x 12V = 240Ws (Power Watt’s NOT sound Watt’s)

TYPICALLY AMPAGES OF MOTORS/PARTS/DEVICES:

AMPAGE (12V dc) rated P/H given as multimeter instant reading	PART
1A to 1.6A (Depends on music played!)	CD/MP3 PLAYER
3A to 20A+ (Depends on the music being played!)	car sound AMPLIFIER 400 Watts 4 Ch
0.01 A	CAR CD PLAYER AMPLIFIER REMOTE
0.03 A	4 WAY CIG LED MULTI ADAPTOR
0.60A (Maximum 0.70A)	PORTABLE DVD PLAYER
2.3 A	CAR INVERTER CAN
5.3A to 6A = Charging Laptop (inverter on = 0.4A, inverter off = 0A)	CAR 12V to 240V 1000 Watt Inverter
0.28 a	MOBILE PHONE CHARGER
0.05 A	SATELLITE NAVIGATION
0.06 A	BLUTOOTH CHARGER
2.6 A est	FLASK
4.6 A	PUMP
0.20A (Depends on function)	LED LIGHT
12.00A	HEADLIGHTS
0.03A	ALARM DRAIN
3.00A	ALARM CENTRAL LOCKING
0.36A	INTERIOR LIGHT
0.08A to 0.20A	ALARM/IMMOBILISER
6A	HAZARD LIGHTS
8A Each	ELEC WINDOWS
10A +	ELEC SUNROOF

IMPORTANT NOTE: Cable size, the bigger the better (Bigger: Diameter or circumference of the cable).

Remember most MultiMeters (£10 Maplin job ok) only test upto 10A 12V DC, more expensive MultiMeters (UNI-T from Maplin £30 why spend any more) test upto 20A 12V DC.