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

 

[srands]

Also remember when you are FITTING (Instead of just testing) power cable, remember the circuit should be adequately fused, for example from SUPPLY (Battery Terminal to Fuse, via ring connector to cable) to the LOAD (Cable, then Motor/Device). Remember the fuse rating is lower then that of the cable ampage, hence if the current is greater then the fuse ampage, the fuse will blow, and if the power negative & power positive touch uninsulated then the fuse will blow because of resistance (The touching of opposites, - and +). Remember a fuse is only a fuse (Cheap & easy to replace), how if you don’t fuse a lead, and resistance and/or maximum is exceeded, then wiring looms and/or motors/parts and expensive & hard to replace (Certainly NOT cheap & easy to replace). Hence on my car I have fused separately the positive & negative, for extra security, as I said before a fuse is only a fuse, to replace fuses, are cheap & easy.


CABLE & FUSE example for 2 typical 12 Volt dc devices

	INVERTER	car sound AMPLIFIER
CABLE	40 A	40 A
FUSE	10 A	30 A
DEVICE (Eg Inverter or Car snd AMP)	4 A	20 A

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:

PART	AMPAGE (12V dc) rated P/H given as multimeter instant reading
CD/MP3 PLAYER	1A to 1.6A (Depends on music played!)
car sound AMPLIFIER 400 Watts 4 Ch, 2 channels bridged powering SUB & 2 channels for 2 6x9’s	3A to 20A+ (Depends on the music being played! Eg about 20A @ Vol 25)
CAR CD PLAYER AMPLIFIER REMOTE	0.01 A (Constant when amp used)
4 WAY CIG LED MULTI ADAPTOR	0.03 A
PORTABLE DVD PLAYER	0.60A (Maximum 0.70A)
CAR INVERTER CAN	2.3 A
CAR 12V to 240V 1000 Watt Inverter	5.3A to 6A = Charging Laptop (inverter on = 0.4A, inverter off = 0A)
MOBILE PHONE CHARGER	0.28 a
SATELLITE NAVIGATION	0.05 A
BLUTOOTH CHARGER (Nokia)	0.06 A
FLASK with optional warmer	2.6 A est
PUMP 12V	4.6 A
LED GRILL LIGHT IN RED	0.20A (Depends on function)
HEADLIGHTS	12.00A
ALARM DRAIN	0.03A
ALARM CENTRAL LOCKING	3.00A
INTERIOR LIGHT	0.36A
ALARM/IMMOBILISER	0.08A to 0.20A
HAZARD LIGHTS	6A
ELEC WINDOWS	8A Each
ELEC SUNROOF	10A +

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.

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

 

[Knobhead]

No......

 

[Silly Sausage]

:confused5::freak::ciappa:

Is this geezer on drugs?

 

[Geordie Spark]

:confused5::freak::ciappa:

Is this geezer on drugs?

If he isn't then he should be !!!

 

[malcolmsanford]

It's a spiffing read

 

[telectrix]

now i know what current my windows require, i shall sleep better at nights. however in the morning, i'll still have to use the window winder handle as they're not electric. now i'm just off to the "manual van window forum"

 

[Knobhead]

:confused5::freak::ciappa:

Is this geezer on drugs?

He can have some of mine, I’ve got plenty.

Codeine Phosphate puts me out like a light!
I take zero ampage then.

 

[drew35]

What was the point in that post? Most multi meters only test to 10amps so for anything more they're useless. All you need is an amp clamp multi meter, good for 600amps, or an inductive ammeter they cost pence. But in this technological world you can buy a digital ammeter with fuse adapter on the end for five quid. A lot easy than than mess in the pictures! Stick to stealing car stereos!

 

[srands]

What was the point in that post? Most multi meters only test to 10amps so for anything more they're useless. All you need is an amp clamp multi meter, good for 600amps, or an inductive ammeter they cost pence. But in this technological world you can buy a digital ammeter with fuse adapter on the end for five quid. A lot easy than than mess in the pictures! Stick to stealing car stereos!

Mate, In the 12V dc car/house world nearly every part/motor with the exception of a car starter motor, is less then 10A, the only other common exceptions being high output car sound amplifiers, perhaps some air conditioning units, so a 10A MultiMeter £10 or 20A MultiMeter £30 is more then adequate.

Clamp MultiMeters and PAT testers are useless junk, they are a joke, they're expensive mickey mouse nonsense(Metal conducts, but NOT wirelessly!)

And the other meters, are a waste of time & money (Make a circuit, wait an hour, or average out 10 mins over an hour). I guess your making reference to finding out the ampage of a starter motor, goto Halfords (Or your main dealer) and ask them the part (starter motor) specification, it sayes on the side of the box.

 

[alarm man]

Mate, In the 12V dc car/house world nearly every part/motor with the exception of a car starter motor, is less then 10A, the only other common exceptions being high output car sound amplifiers, perhaps some air conditioning units, so a 10A MultiMeter £10 or 20A MultiMeter £30 is more then adequate.

Clamp MultiMeters and PAT testers are useless junk, they are a joke, they're expensive mickey mouse nonsense(Metal conducts, but NOT wirelessly!)

And the other meters, are a waste of time & money (Make a circuit, wait an hour, or average out 10 mins over an hour). I guess your making reference to finding out the ampage of a starter motor, goto Halfords (Or your main dealer) and ask them the part (starter motor) specification, it sayes on the side of the box.

interesting thread srands,it inspired me to have a bit of a tinker with my own car,tho i think ive bit off more than i can chew...look forward to your help..:uhoh2:

 

[Silly Sausage]

:uhoh2:


View attachment 7834

Hahaha!!! Can't stop laughing now...

 

[Des 56]

Remember a fuse is only a fuse (Cheap & easy to replace), how if you don’t fuse a lead, and resistance and/or maximum is exceeded, then wiring looms and/or motors/parts and expensive & hard to replace


Why would you want to fuse the negative as well as the positive
A circuit will be disrupted with a fuse in the positive only,adding another fuse in the negative has no benefit,its a waste of time and effort


Some starter motors can draw current upwards to 200 amp and will operate directly from the battery via the solenoid,
If you double fuse everything ,does that "everything" include your starter motor

Using thick cables to overengineer for heavy future loads
Relays and solenoids negate the need to switch the bulk of these loads,localised larger cable is the time tested best method

 

[Knobhead]

srands, would you please go to DIYnot, or did they send you here? I’m sure there’s people there that will listen to you

View attachment 7835

 

[srands]

To comment further on calculating AMPAGE drawn, there was discussion that electric motors are all mostly low ampage (Below 10Ah), with the exception about knowing the ampage of a car's greatest electrical consumption part, a STARTER MOTOR, well goto Starter Motor | Quality Starter Motors for any car (Or your main dealer) and ask them for the parts (starter motor) specification, it sayes on the side of the box, or motor.
Note: If starter motor specification is in KW:
KW / 1000 = Watt's
Watt's / 12 V = A. This figure is an instant, as the starter motor drain is for a second (NOT continuously), then the ignition key is released (Starter motor turned OFF) as the engine is started, then the alternator produces current, recharging the battery, obviously there will be small current drains in Ah from small motors/parts, for example, electric windows, indicators, car cd/mp4/dvd player, lights, fan/air con, etc.

FURTHER DETAIL:

BATTERY & STARTER MOTOR EXAMPLE:
CAR BATTERY: 56 Ah (* 10 = 560 A [EN])
STARTER MOTOR 1.7 KW (/1000 = 1700 WATTs / 12 VOLTs = 142 A [EN])

Obviously the car manufacturer deems what is an appropriate battery Ah for their manufactured car model.

An Amp-Hour (ampere-hour, Ah) is a way of describing a battery's capacity - how long it will run before it is drained down. To be more specific: the amp-hour rating for a given battery is the maximum amperage that can be drawn continuously until the battery is completely flat, over a specific time period.

AH stands for amp hours
10 amp hours =
~ DrAW 10 amps for 1 hour
or
~ Draw 1 amp for 10 hours
Or
~ Draw 11 amps for 54 minutes (0.9 hours)
The faster you draw amps out of your battery the fewer amp hours you get in total, and the shorter the life of the battery.

Ampere-hour - Wikipedia, the free encyclopedia
Starter Motor | Quality Starter Motors for any car

 

[Silly Sausage]

Thanks for link to Ampere-hours, you learn something everyday!
Could you please explain to me kWh, I'm just completely baffled by them?
Thanks in advance
A