What in the ....?????? Low voltage reading, yet full battery and alternator working.

Topic: What in the ....?????? Low voltage reading, yet full battery and alternator working. (Read 19610 times) previous topic - next topic

What in the ....?????? Low voltage reading, yet full battery and alternator working.

Reply #90 – July 03, 2014, 04:17:15 PM

I run it that way because it's adequate and I had it just laying around.

What in the ....?????? Low voltage reading, yet full battery and alternator working.

Reply #91 – July 03, 2014, 04:53:38 PM

Right, but in many vehicles it was designed to run this way. WHY???

BTW -- Voltage across the battery terminals on this 90° + day with humidity high enough for one to cut with a knife? 14.24

Considering that today's conditions traditionally will make it read lower that say 50° I'm happy.

I'll get some gas later and put her through the paces.

What in the ....?????? Low voltage reading, yet full battery and alternator working.

Reply #92 – July 03, 2014, 05:32:24 PM

I wouldn't be surprised to see a 70 amp peak load if you have electronic goodies.

each bulb pulls a constant 1 amp load.how do i know this? I use extra tail light bulbs to discharge my model airplane batteries. 12v's. = 12 watts. guess what happens at 14.8? Its well over 20 watts. your car should run at 13.5-14.2 ish.

so, 8 tail lights bulbs. there is 8-14 amps. Two 55 watt head lights, another 4 bulbs in front. interior lights, gotta be 10 of those, plus your map lights, sun visor bulbs, dash cluster, lets say you have a 200 watt radio, might only pull 25 watts, but could spike quite a bit highet.

fuel pump, mine said it required 10 amps minimum, power seats, power recline, lets say you use your cigarette lighter to actually light a cigarette as i do frequently, that's well over 20 amps.

and we haven't even started te car yet, just adjusted seats, turned on the key and headlamps.

now why did these cars have a alt with a single 10 guage feed and an alt that puts out about 35 amps at idle? My guess is the same reason why they melted wires.

What in the ....?????? Low voltage reading, yet full battery and alternator working.

Reply #93 – July 03, 2014, 07:11:56 PM

Thanks, stacks, you've made my case for the factory charging system's inadequacy.

What in the ....?????? Low voltage reading, yet full battery and alternator working.

Reply #94 – July 03, 2014, 07:56:13 PM

Foe can you tell me as a dealer tech what the running load on an alternator is at 1/2 Load. The stock TC alternator is 65 AMPS and bruiser is 100% stock with no charging issues whatsoever. bruiser is a 1987 TC electric brakes power seats electronic ride control electronic fuel injection premium sound system electric fans and AC and i am sure you know the rest with a 65 AMP from the factory and a big battery to boot. It runs and drives perfectly and the 65 amp alternator handles the electrical load just fine. So much for the 70 AMP loads. Like i said the DURAMAX early ones came with 105 AMP alternators from the factory with a snow plow option. No charging issues there and the truck has 2 battery's. I think in reality most mechanics do not know how a charging system works. Or how it accomplishes it's job. Why is it that every ammeter i have installed or a factory one always reads ZERO after the initial recovery of the battery from a start. Hook up a VAT and plot a charging system current load. 70 AMPS is a hell of a lot of load. Have a good holiday guys

Stacks what you are doing is adding up loads that are not on all the time. Do you not understand this. It is like who cares if the seats draw a million watts. It is INTERMITTENT. If you add up every load in the car the alternator would have to be 200 AMPS CONTINUOUSLY. And no alternator in a car configuration can do that. Example how could an alternator supply that much current with a single V belt for example. Serpentine belts are different. But could you imagine the load it would put on the belt and engine if it ran at 200A continuously. Foe the reason fords have charging issues is quite clear. There alternators are not the best and they are under driven quite often. reason being the big diesel pickups have 2 alternators. CORRECT??? Stacks when was the last time you seen an alternator wire MELTED from a load condition??? Also charging voltage is not constant. If the battery picks up it goes up. If it is hot under the hood it goes down Basically an alternator does not put out as i said 1/3 of its capacity rating in amps. If it puts out 100% of it's rated output it will burn out IT CAN"T continually produce its max rated output it will burn out. By the way their are millions of cars on the road with under-drive pulleys. What does that tell you ??? So if you have a 100Amp alternator and under-drive it by whatever the ratio is and it still charges OK whats with that. Bottom line alternators do not work very hard at all. PEAK LOADS DO NOT COUNT!!! That is not how the engineers design alternators for cars. Peak load is never used. They do not count the cigarette lighter in the equation. Thanks and have a great FOURTH!!

What in the ....?????? Low voltage reading, yet full battery and alternator working.

Reply #95 – July 03, 2014, 08:59:24 PM

I don't know what you've got, Tom, But when I'm running on a cool night, I'm pulling a constant load of 58-66 amps. I've made a few electrical upgrades along the way, sure, but my night-time load is greater than the max of the stock system. Winter before last when I drove the car, my loads were higher still, averaging in the upper 70's and low 80's (in fairness, after 25 minutes or so defrost shuts off and the EATC spins the blower down). This is why the factory system is inadequate. In winter, I would get a dead battery once every roughly 12 days before 3G. Some loads are constant, even a 130A max 3G will only push 85 or 90 at idle with stock pulleys, but my stock 60A unit mustered 38 whopping amps at idle. In summer I pull a minimum of 42A once I'm warmed up at idle (w/AC on and foot on brake). After 3G, I don't max my alternator out so that I'm drawing my battery down. Problem, solution, happiness. Nobody in their right mind should run under-drives.

What in the ....?????? Low voltage reading, yet full battery and alternator working.

Reply #96 – July 03, 2014, 09:53:43 PM

Well many run under-drive pulleys just look at this site. Bottom line here is that most cars do not have an alternator bigger than 100A if it is older and newer cars do not have alternators bigger than 140 and the norm is around 120. And none of them come with wire bigger than 8AWG on average, so one of us is wrong. I am not saying a bigger alternator is BAD. What i am saying is different units perform differently. GM alternators are the best bottom line. Ford alternators are not very good by design. That is why an F250 diesel needs 2 alternators at 130A each and one GM 105 AMP alternator is ok for Chevy trucks. I am willing to bet the total load of a modern car today is around 40- 50 Amps. And i am totally aware of increasing the wire size. But people go nuts. On another site a guy is using a 3/0 wire to his alternator. Itis getting rediculous at best. By the way my 68 Camaro came from the factory with a big pulley alternator and it's output is a whopping 32 AMPS. The optional alternator is 42 AMPS. Have a great weekend.

The Midnighter has a 130 3G and bruiser has a stock 65 Amp 2G. With that i am not saying an upgrade is bad what i am saying is those so called 200AMP aftermarket units are BULLshiznit and a LIE. Some companies boast there stock case ford alternators are 250AMPS. That is BS and i think we can both agree with that. Have a good Holiday FOE!!

What in the ....?????? Low voltage reading, yet full battery and alternator working.

Reply #97 – July 03, 2014, 10:09:36 PM

Quote

Nobody in their right mind should run under-drives.

I've always agreed with this sentiment.
Speaking of this, I've always wondered something. AFAIK, the stock size crankshaft pulley on the Cougars and Thunderbirds is the same as the truck pulley, which is LARGER in diameter than the 87-93 Mustang 5.0 HO crank pulley. Was a reason possibly to keep the alternator RPM's up a bit thus helping to charge a more electrically laden system at low engine RPM's?

In stock form, the redline on the HO is higher than the others, so an alternator behind a larger pulley on the non-HO would still able to be driven and not over-revved.

What in the ....?????? Low voltage reading, yet full battery and alternator working.

Reply #98 – July 03, 2014, 10:19:05 PM

I see under- drives all the time and surprisingly enough with no charging issues. Normally an alternator runs 3 times engine speed not to exceed 16000 RPM'S. Example i shift my Camaro at 7400 Rpm's so my alternator is spinning quite fast. But i UP graded it to 140 Amps compared to the stock 105 from the factory and installed a bigger pulley. So my idle charging is reduced but i have no choice as the alternator will rip it self apart if i spin it to fast. But!!!! Gm alternators charge at a lower voltage after recovery. normally 13.2 compared to 14.7 on most older cars. ECM controlled alternators run lower voltages for hot charging to increase MPG. In the future charging systems will be designed for max fuel economy. So i had to slow down my alternator because of the high rpm capability of my motor. Some foreign cars have a clutch on the AC and some on the ALT so they drop out at high RPM. Ford also uses a free wheeling pulley on COP CARS. It only turns in one direction and has a one way pulley. there is a lot of stuff coming out to save fuel and cut down on Para-static loads. The future will be interesting at best in the car business. Have a great weekend Guys,

What in the ....?????? Low voltage reading, yet full battery and alternator working.

Reply #99 – July 03, 2014, 10:34:34 PM

Quote

In the future charging systems will be designed for max fuel economy.

Hmmmm...Voltage sensor across the battery terminals built into the car and letting the PCM know when and when not to power up the alternator..... Would a type of clutch or an electrical switch be more efficient/durable? Better yet, will alternators even need to be belt driven in the future? Electric water pumps, EPAS....... I would think an electrically driven alternator would be a logical progression. I'm not alone apparently: http://www.vanner.com/vanner%E2%80%99s-hybrid-beltless-alternator-released-by-vanner-for-allisonhybrids/

Packaging/size will need to be addressed for passenger car applications.

What in the ....?????? Low voltage reading, yet full battery and alternator working.

Reply #100 – July 03, 2014, 10:37:21 PM

Check this out. You can install one on your car and they work great.

http://www.decouplerpulley.com/files/RotoRxbrochure.pdf

What in the ....?????? Low voltage reading, yet full battery and alternator working.

Reply #101 – July 03, 2014, 10:37:44 PM

Yes controlling the ALT through the ECM will be the norm for fuel economy. I went to a denso seminar and the engineers showed us how the alt is shut down on highway speeds to save fuels. Some had clutches some were ECM controlled. The future is going to be either neat to some or outrageous to others, In my view a nightmare will explain it better. Take stop light engine off features that actually stop an engine while waiting for a light change and the engine starts instantly with no hesitation at all. The future will be NUTS to say the least.

What in the ....?????? Low voltage reading, yet full battery and alternator working.

Reply #102 – July 03, 2014, 11:13:27 PM

Quote from: TOM Renzo;435443

Well many run under-drive pulleys just look at this site. Bottom line here is that most cars do not have an alternator bigger than 100A if it is older and newer cars do not have alternators bigger than 140 and the norm is around 120. And none of them come with wire bigger than 8AWG on average, so one of us is wrong. I am not saying a bigger alternator is BAD. What i am saying is different units perform differently. GM alternators are the best bottom line. Ford alternators are not very good by design. That is why an F250 diesel needs 2 alternators at 130A each and one GM 105 AMP alternator is ok for Chevy trucks. I am willing to bet the total load of a modern car today is around 40- 50 Amps. And i am totally aware of increasing the wire size. But people go nuts. On another site a guy is using a 3/0 wire to his alternator. Itis getting rediculous at best. By the way my 68 Camaro came from the factory with a big pulley alternator and it's output is a whopping 32 AMPS. The optional alternator is 42 AMPS. Have a great weekend.

The Midnighter has a 130 3G and bruiser has a stock 65 Amp 2G. With that i am not saying an upgrade is bad what i am saying is those so called 200AMP aftermarket units are BULLshiznit and a LIE. Some companies boast there stock case ford alternators are 250AMPS. That is BS and i think we can both agree with that. Have a good Holiday FOE!!

Not all Ford diesels have 2 alternators, Tom. In my career I've seen like 5.

What in the ....?????? Low voltage reading, yet full battery and alternator working.

Reply #103 – July 03, 2014, 11:16:55 PM

Quote from: TOM Renzo;435449

Check this out. You can install one on your car and they work great.

http://www.decouplerpulley.com/files/RotoRxbrochure.pdf

I've got something like this on mine. I snagged it off a police alternator. When I shut down and the engine stops, I can still hear the alternator spinning down. Takes 45 seconds or so. 3G is a ball bearing alternator, so makes sense. It's kind of a cool sound.

What in the ....?????? Low voltage reading, yet full battery and alternator working.

Reply #104 – July 03, 2014, 11:22:21 PM

Quote from: TOM Renzo;435450

Yes controlling the ALT through the ECM will be the norm for fuel economy. I went to a denso seminar and the engineers showed us how the alt is shut down on highway speeds to save fuels. Some had clutches some were ECM controlled. The future is going to be either neat to some or outrageous to others, In my view a nightmare will explain it better. Take stop light engine off features that actually stop an engine while waiting for a light change and the engine starts instantly with no hesitation at all. The future will be NUTS to say the least.

Auto start/stop is why we keep recalling 1.6L Escapes for localized overheating. It's got 3 independent, yet linkable cooling loops, to keep heat coming with the engine off and so on. It's been a big pain in the ass.