I am working on a project on my Fiero and am having trouble calculating the total amps drawn by my car; I have a 8 SE V6 with basically no options (No PW/PDL/PM or A/C).....So what would the amp draw be for a 2.8 V6 running, with heater fan on #2, headlights on high beam and the wipers running? If I just add up all of the fuse numbers I get somewhere around 160 amps but I seriously doubt my electrical system is using that much at any moment......
Does anyone here have a good estimate of the number of amps drawn?
The easiest way would be to read the current flow directly with an ammeter on the red fuse link wires connected to the battery junction terminal. Depending on how you measure, collectively or individually, you may find a clamp-type ammeter will be necessary since your total draw will be roughly around 30 amps (that is only a guess). Since I've only used direct current measurement in my electronic work, I'm not sure if clamp style meters are influenced by nearby magnetic fields that may affect their accuracy. Anyone?
Does anyone here have a good estimate of the number of amps drawn?
The problem is more difficult as the car gets older.
The Ogre's cave has a page on this subject that is helpful. (Electrical/General/Electric Motors)
Example:
Radiator Fan Motor is rated at 150 Watts and uses 10-11 Amps about 14 Volts normally. But have a mess up ground and now get 10 volt, motor uses 15 amp. Really bad ground? Say 7 volts? Motor uses nearly 21.5 amps! That will blow the motor and/or relay to controls the motor.
[This message has been edited by Gall757 (edited 10-25-2019).]
See my Cave, Watt Story gives some more examples etc.
Fuse amp rating is Not what amps draw by whatever. Fuse are to stop Battery and Alt dumping Hundreds of Amps in a short circuit frying the cars.
Actual HL draw depends just what HL are installed. "Max Legal" High Beam on paper w/ engine running is typical 65w/14v=4.7a each, x2 = 9.4a for 2 bulbs but many people have illegal HL pulling more power. But Unless you drive on roads w/ very little traffic at night, you can't use High Beam often in most areas. Example: PA's NE Extension to PA Turnpike is hard to use HB in many sections now unless maybe 2 to 4 am.
Best and simple is using DC Amp Clamp to see Amp Draw without disconnect/cutting. Warning: Most meters w/o that feature only handles 10 to 20a on a builtin shut and many cheap ones have big problem handling even that. IOW If you have a shut meter in circuit and turn on a few things you better hope has a fuse or you likely will melt the meter, the probes or catch fire. Yes we use them for cars but mostly to look for Battery Leaches and most are well under 5a.
Why do you think you need this? Example: To save weight using smaller alt and/or battery?
Size of either is not really a function power drawn by a car. For most cars... "Size" of battery is about Starter the car in all kinds of weather, how fast does ECM etc Standby Power kill the battery when parked and how long battery runs a car w/ dead alt. "Size" of Alt is directly related to amp draw but also more. Big one is Old SI alts are way less efficient to make power vs. CS-130 w/ around same size and weight.
But even that in very general info. Often SI and others don't make full power all the time. IOW the 95a or whatever is advertise spec for an alt is only Peak Power. So If you run PW at idle and alt can't make enough, the battery delivers that power for the seconds you push the button.
Unlike many newer cars w/ smallest alts and often bigger batteries then Fiero and others to pad MPG numbers to US EPA and other Governments around the world. But that's for a whole other topic.
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
I moved the battery up front- but didn't like the "Safety" of having a Welding-size cable (Always energized) running UNDER the car next to the FUEL tank, So I installed a Ford-style separate starter solenoid that powers the big starter cable only during start, and then a AWG 8 wire to run the actual car- I ran that wire in with the Negative battery-to-block cable in Scd 40 tubing...But I have planned on installing a large fuse in that AWG 8 wire in case of "High-centering" so that the wire shorts and immediately blows the fuse shutting off power.
I have one of those really BIG fuse holders, but am not sure what size fuse to use- 30, 40, 50, 60- maybe even 100.......Just trying to set it up so I don't become famous as the guy who BLEW-UP his Fiero- with him in it...........(I know this isn't the perfect set-up...but the best I could figure out)
I wanted to cover the extreme power situation- Driving at night, in the rain on a backroad- high beams on, heater fan on 2, and wipers going full speed......(plus the stupid rad fan going also.....)
You could always runs pvc style conduit underneath your vehicle. Also if you have a good battery to chassis ground, you can then ground the engine to chassis, without need for long negative cable.
First- I ran the wires front to rear in Schedule 40 plastic conduit...But that is not going to protect the wires in a serious high-center situation.
Second, I am not interested in having a fuse to "protect the wire from burning up under normal load"- I am interested in having a fuse that has the proper capacity for all the car's needs- but considering that, is as low as possible to "pop" when an accident occurs if there is a short in the system.
I can get a Maxi fuse in 40 up to 120 amp range. Maybe I will have to buy an assortment and then try from small to big until one survives running everything. I know a lot of the systems have run and SURGE power levels......
I have seen some numbers; Headlights on high beam just under 10 A....Rad fan is at 11 A....What does the V6 draw during normal running (Computer, ignition, Fuel pump and injectors) and what about the heater fan? And the wipers? (I don't have the trunk fan at the moment but may add it in a modified installation) I see on Ogre's page that he estimated 32-33 amps PLUS some additions- maybe 60 A would be enough...?
[This message has been edited by cvxjet (edited 10-26-2019).]
You are worried about an accident that is so rare, that there is no research to point to and say "YES!...use a 60 amp. fuse!" So whatever your comfort level is, go for it, but my lawyer would advise against giving you an absolute number....
Second, I am not interested in having a fuse to "protect the wire from burning up under normal load"- I am interested in having a fuse that has the proper capacity for all the car's needs- but considering that, is as low as possible to "pop" when an accident occurs if there is a short in the system.
Have you thought about that statement?
Protecting the wire is why the fuse is sized properly. A properly sized fuse will deliver the desired protection in an accident, and protect the wire from damage if the amp draw from your normal load is too high. Oversizing the fuse, with too much amp draw from the normal load, will burn your car down just as easily as a dead short with no fuse protection. If your amp draw is too high under normal load, you need to upsize the wire, and provide proper fusing.
Originally posted by cvxjet: First- I ran the wires front to rear in Schedule 40 plastic conduit...But that is not going to protect the wires in a serious high-center situation.
Second, I am not interested in having a fuse to "protect the wire from burning up under normal load"- I am interested in having a fuse that has the proper capacity for all the car's needs- but considering that, is as low as possible to "pop" when an accident occurs if there is a short in the system.
I can get a Maxi fuse in 40 up to 120 amp range. Maybe I will have to buy an assortment and then try from small to big until one survives running everything. I know a lot of the systems have run and SURGE power levels......
I have seen some numbers; Headlights on high beam just under 10 A....Rad fan is at 11 A....What does the V6 draw during normal running (Computer, ignition, Fuel pump and injectors) and what about the heater fan? And the wipers? (I don't have the trunk fan at the moment but may add it in a modified installation) I see on Ogre's page that he estimated 32-33 amps PLUS some additions- maybe 60 A would be enough...?
The Fuse Size is Directly related to Wire Size as olejoedad said. 8ga wire likely only handles 50a safely so fuse at 50a or less.
Is Same rules for House/Commercial building wiring... I think (Not digging thru building codes right now.) 12ga gets 20a fuse/breaker. 14ga gets 15a fuse/breaker. And F'd the Amps used by whatever. If a product needs more then those, must install big wire and big breaker like most electric stoves, driers and water heaters. Those wire sizes can handle more amps depending on install conditions but nobody will approve them w/ bigger breaker. Last E water heater I installed calls for 10ga min wire w/ double 30a breaker for 240vac circuit in the US but likely doesn't use 30a when on.
That also depend on insulation many times. Standard PVC insulation on most wires doesn't like Heat Cold or being loaded/compressed in/around corners etc. and can fail soon under these conditions. Is part of why many use "Welder Cable" for main cables for front mounts. Thick heavy insulation can take more abuse then most most other types. Like also because many are very flexible when cold and is exposed to welding sparks etc is likely fire resistant too. Is why many circuits you add to a car often needs high heat wire w/ insulation rated at 105°C or higher but Most install crap wiring make cheap and wonder why have problems or a fire later.
"Small" wire to battery main jobs are carry enough "backup" power to start the car, charging the battery and maybe makeup low amp output for a alt at idle. Is Not made to handle everything On and can heat up and even fry fuse links between battery and + box if force do to so in many cars.
Many other cars have 2 to several thin wires directly to the battery to spread amp draw to the rest of car. Example: The alt and engine on 1, the rest on another 1 or more. Fiero and some other GM vehicles are same but added that extra + box so you don't damage all of those wires changing/disconnecting the battery. OE Fiero battery + cable doesn't have a fuse link because everything else to + box have fusible links. Then they have "sub" fuses/links in the fuse box etc. ACDelco replacement cables have links but most others do not but need them and installed wrong by most DIY and Repair Shops.
If engine is off or alt dies at night or other time w/ a lot of things On... Even if thin wire(s) handle the load, the battery won't last long. Reserve Cap etc are calc under special rules and basically runs only the engines on most vehicles for a few minutes to an hour depending on battery type/design.
Is funny, in the sad way, you and others think fusing/switching the wires is going to be safe in a crash for front mount batteries in at Fiero. So Wrong on so Many levels. Huge one is battery itself. Front end crash like in crash test videos and similar then battery can/will turn into a loose cannon/wrecking ball, be crush, or both, and likely short out. Fiber glass and metal battery box attach to "plastic" tire wall have Very little strength in a crash. Worse, Metal boxes can move and short out battery terminals etc. If terminals pointed to spare tire, the spare can do same. Shorted battery can dump 300+ amps for a long time yet your worried about 50a circuit and have no clue what the that circuit does to start with. Worse now your saying you're going to put a penny in fuse box (Was very real problem and cause Many house fires and is still a common name for over rated fuse/breaker for a given wire.) so fuse will last... Good luck w/ that plan.
Originally posted by dear1700: You could always runs pvc style conduit underneath your vehicle. Also if you have a good battery to chassis ground, you can then ground the engine to chassis, without need for long negative cable.
Battery to frame then frame to engine only adds more resistance that can kill the starter. Worse as rust etc attacks every contact in months to years of service. Same problem covered in my Cave, Electric Motors
Battery Should have big ground to block/head and small ground to frame. Front battery Fiero is same.
[This message has been edited by theogre (edited 10-27-2019).]
Geeez....Ok.....Look at Evel Knievel....Crashed so many times on his bike-broke every bone in his body several times- yet he lived to the age of 69. I knew a lady, she twisted her ankle- didn't feel good so went and laid down.......Died from a twisted ankle (Basically)....
There are all different ways to crash a car- certainly you can have the front-mount battery create a number of problems.....I am trying to make it relatively safe- shorting wires against the fuel tank seems like one of the bigger dangers......
I have been driving my car with this setup for 8-10 years- no problem; the AWG 8 wire runs everything on the car- have driven it at night with headlights, wipers and fan running....can't guarantee the rad fan was running. I just want to get a fuse that will carry what the car can possibly use yet has some possibility of shutting down the system in event of a high-center situation.
I would love to own a large corporation that could do full NHTSA vehicle safety testing + crash testing...But I am a little short on funds at the moment! (Shouldn't have bought that last Churro!)
I moved the battery up front- but didn't like the "Safety" of having a Welding-size cable (Always energized) running UNDER the car next to the FUEL tank, So I installed a Ford-style separate starter solenoid that powers the big starter cable only during start, and then a AWG 8 wire to run the actual car- I ran that wire in with the Negative battery-to-block cable in Scd 40 tubing...But I have planned on installing a large fuse in that AWG 8 wire in case of "High-centering" so that the wire shorts and immediately blows the fuse shutting off power.
I have one of those really BIG fuse holders, but am not sure what size fuse to use- 30, 40, 50, 60- maybe even 100.......Just trying to set it up so I don't become famous as the guy who BLEW-UP his Fiero- with him in it...........(I know this isn't the perfect set-up...but the best I could figure out)
I wanted to cover the extreme power situation- Driving at night, in the rain on a backroad- high beams on, heater fan on 2, and wipers going full speed......(plus the stupid rad fan going also.....)
If you are that concerned about a front mounted battery causing a battery cable fire in an accident, the simple solution is to add a crash battery disconnect fuse.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
If you are that concerned about a front mounted battery causing a battery cable fire in an accident, the simple solution is to add a crash battery disconnect fuse.
Do you have a source? Looks like the car needs to have air bags.
Dennis- I had not heard of those- How do they work? What "Sets them off"...? Are they self-contained or do they need a crash safety computer to tell them when to actuate?
Dennis- I had not heard of those- How do they work? What "Sets them off"...? Are they self-contained or do they need a crash safety computer to tell them when to actuate?
You would need to hook one up to a simple crash sensor circuit. You would probably need the sensor, a relay and the crash battery fuse switch.The sensor senses the crash and shuts off the battery fuse. Now if we want to take a simpler approach without having to do some engineering, Olejoedads solution is easier, probably less expensive and more practical
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
Dude! Put a 50A fuse on the line and quit agonizing!
GEEEE-Sefima! This is what I planned on doing...I just wanted a fuse that was sized right. and I do not have a loop tester- otherwise I would use it and get an accurate measurement.
I want to tell you guys; I think "outside the Box" a lot- have come up with some good things- and have had some failures. I rebuilt my jet boat 460 and pump so that my JET boat gets BETTER Fuel efficiency than the DD Ski boats- and also set the boat up so it is a good slalom ski boat (2 expert skiers were amazed)...But trying to invent a variable nozzle (Like on jet fighters) was a complete fail- Did not work at all.
Set up my 1973 Mustang so that it both handled like a friend's 3 Series BMW and rode like it too. My Bimmer racing friend was impressed...But my fail was that EVERYTHING on that car had to be done 2-3 times before it was fixed....And sometimes NEVER fixed...(I started doubting my abilities- until my GF told me to "Write down everything you did and where the failure occured"....Bad parts (Cause I was buying CHEAP (Low income during that time)
I do appreciate the responses.....This site is made up of great people (And a few wise-acres....But enough about me!)
So I now have a 60 amp fuse in there- could not locate a 50 amp in the local stores...I also have an 80 as an emergency replacement if it just quits on me while out driving. I tested it with the engine running, the headlights on high beam, and the heater fan on full- the alternator wasn't particularly happy- but the fuse did not blow and the wire was not hot anywhere. At some point I will get a 50 amp fuse (And maybe test with a 30-40 amp fuse to see it fail)
Next up, I'll go off-roading and try to high-center it! (Just kidding)
