Baseline electrical load + alternator options

[kobachi]

Now that we're in the cold weather, I've started using my heater. I notice with the headlights on and the fan/heater on, my voltometer bounces around a bit. (Stabilizes if I turn off the cabin fan.) I'm about to add a subwoofer to my stereo setup, which makes for 2x300W RMS amplifiers (Rockford Fosgate PBR300X2 and PBR300X4).

I'm concerned that my alternator isn't going to be able to handle the additional current demand. Does anyone know what the "baseline" current demand for a running car with headlights, heater+fan, and radio is?

I had a peek and discovered I have the 90A Motorola alternator. I see DMCH sells a 140A alternator for $198, which seems a little steep to me. Are there other high-amp alternator options out there? Is it cheaper to source one from somewhere else, or is the DMCH unit the right choice?

[DeLorean03]

Give John a call and see what he can do for you:

http://specialtauto.com/delorean-parts/alternators.html

Odd that his prices are no on the page, but he has a decent number of options for you!

972-564-9321

[NightFlyer]

Now that we're in the cold weather, I've started using my heater.

Noticed that you're located in Washington state, yes? I'm also guessing that you guys get/have snow and salt the roads to keep them passable, yes?

So, I have to ask - are you driving your DeLorean in the snow/salt?

I want to make it clear that I'm not making a judgment on driving a DeLorean in the snow/salt, but am only curious as to whether or not this owner is actually doing so.

[DMCMW Dave]

At one time we measured a car (actually my own car) with everything turned on (lights on bright, A/C, blower on full speed, FACTORY radio) at just over 90 amps. So you can kind of see why the factory alternators were in trouble even on a good day, and when alternators are 30 years old and/or hot it goes downhill from there.

When you start adding a thumpin' stereo and idle the car on a hot day it's worse. The really serious folks install a second battery instead of the spare tire.

[NightFlyer]

At one time we measured a car (actually my own car) with everything turned on (lights on bright, A/C, blower on full speed, FACTORY radio) at just over 90 amps. So you can kind of see why the factory alternators were in trouble even on a good day, and when alternators are 30 years old and/or hot it goes downhill from there.

When you start adding a thumpin' stereo and idle the car on a hot day it's worse. The really serious folks install a second battery instead of the spare tire.

In addition to what you listed, was the 90A draw experienced with both cooling/radiator fans in operation?

[kobachi]

At one time we measured a car (actually my own car) with everything turned on (lights on bright, A/C, blower on full speed, FACTORY radio) at just over 90 amps. So you can kind of see why the factory alternators were in trouble even on a good day, and when alternators are 30 years old and/or hot it goes downhill from there.

When you start adding a thumpin' stereo and idle the car on a hot day it's worse. The really serious folks install a second battery instead of the spare tire.

This is exactly what I was looking for. I won't be running my stereo anywhere near full-power, but if I was, 600W at 13.8V ~= 44A, +90A = 134A. So looks like the 140A alternator would probably be just fine for me.

Back to my original question of: isn't $198 a little steep for an alternator?

[kobachi]

Noticed that you're located in Washington state, yes? I'm also guessing that you guys get/have snow and salt the roads to keep them passable, yes?

So, I have to ask - are you driving your DeLorean in the snow/salt?

I want to make it clear that I'm not making a judgment on driving a DeLorean in the snow/salt, but am only curious as to whether or not this owner is actually doing so.

I live in Seattle, where we only get a few days of snow/ice per year. We don't generally salt in western WA. They might salt on the east side of the mountains.

So no, I will not be driving in the salt, and not in the snow/ice unless absolutely necessary.

[DMCMW Dave]

This is exactly what I was looking for. I won't be running my stereo anywhere near full-power, but if I was, 600W at 13.8V ~= 44A, +90A = 134A. So looks like the 140A alternator would probably be just fine for me.

Back to my original question of: isn't $198 a little steep for an alternator?

You can always find stuff cheaper.

[vwdmc16]

It would be a good idea to add atleast one capacitor in with the stereo to dampen the voltage drops.

[kobachi]

It would be a good idea to add atleast one capacitor in with the stereo to dampen the voltage drops.

I am not convinced about capacitors. http://fatfist.hubpages.com/hub/Car-Audio-CAPACITORS-Why-They-DONT-Work

[djdogbone]

I've noticed a lot of people recommending increasing the breaker for the AC fan for speeds 3&4...my cabin fan too would make my volatage drop. I wentvso far as to buy the breakers and I had a thought; my AC fan squeaks a little. I pulled the AC blow motor and it was almost completely seized!

I bought a Seiman's fan off of e-bay, did a fan blade swap, installed it and it fixed my issues - the fan stopping on speeds 3&4 after running for awhile and my bouncing voltage meter.

I recommend, from personal experience, that you crawl under the passenger seat dash and look at that fan motor. Min
Swapping the fan sure helped resolve some issues for me.

-djd

[kobachi]

I've noticed a lot of people recommending increasing the breaker for the AC fan for speeds 3&4...my cabin fan too would make my volatage drop. I wentvso far as to buy the breakers and I had a thought; my AC fan squeaks a little. I pulled the AC blow motor and it was almost completely seized!

I bought a Seiman's fan off of e-bay, did a fan blade swap, installed it and it fixed my issues - the fan stopping on speeds 3&4 after running for awhile and my bouncing voltage meter.

I recommend, from personal experience, that you crawl under the passenger seat dash and look at that fan motor. Min
Swapping the fan sure helped resolve some issues for me.

-djd



(breaker == fuse? Seiman's == Seimens?)

This is awesome advice, thank you. I'll be under there anyway as I'm thinking of hiding the PBR300X4 in there.

[kings1527]

I've noticed a lot of people recommending increasing the breaker for the AC fan for speeds 3&4...my cabin fan too would make my volatage drop. I wentvso far as to buy the breakers and I had a thought; my AC fan squeaks a little. I pulled the AC blow motor and it was almost completely seized!

I bought a Seiman's fan off of e-bay, did a fan blade swap, installed it and it fixed my issues - the fan stopping on speeds 3&4 after running for awhile and my bouncing voltage meter.

I recommend, from personal experience, that you crawl under the passenger seat dash and look at that fan motor. Min
Swapping the fan sure helped resolve some issues for me.

-djd

Replacing the fan seems to be the long-term solution. When the fan starts to go out (typically the original 32-year old fan) it starts to draw more amperage and that's what trips the breaker. The short-term solution is to increase the breaker to a 30A.

[djdogbone]

The AC fan has a thermal breaker for speeds 3&4, not a fuse. It is supposed to trip when the circuit gets overloaded.


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[djdogbone]

I don't know about sort term vs long term when the fan is only $26 and about an hour of your time. The Seiman's fan is a direct swap. The only bugger is the bead of silicone sealer that needs to be applied all around the fan. Just need a steady hand.


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[kobachi]

Where in the parts diagram is this fan located?

[kings1527]

I don't know about sort term vs long term when the fan is only $26 and about an hour of your time. The Seiman's fan is a direct swap. The only bugger is the bead of silicone sealer that needs to be applied all around the fan. Just need a steady hand.


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I'm showing the replacement fan at $104 thru DeLorean.com. Is the Sieman's fan really that much cheaper? That's a big spread. Too big.

http://store.delorean.com/c-361-7-1-0-evaporator.aspx

[David T]

I'm showing the replacement fan at $104 thru DeLorean.com. Is the Sieman's fan really that much cheaper? That's a big spread. Too big.

http://store.delorean.com/c-361-7-1-0-evaporator.aspx

You can also replace the radiator fans with Spalls or some other more efficient fan that draws a LOT less power. That 140 AMP alternator cannot output all 140 amps at idle. That is why you need more than one battery if you are going to be using that much power. To handle the power requirements during those short times you are actually idling, like at a stop light or in traffic. For serious sound you should be running a separate power bus and a battery just for the sound system. The capacitors are for the very short high power events like bass notes where you have to move those bass speakers quickly. Even after you are idling the alternator has to replace all of the power you just sucked out of the batteries so it needs even more than 140 for a while. Serious stuff. The whole electrical system in the Delorean was not designed for any of this (Damm Lucas!). Even more so the ground (earth) system. Add to that 30 + years of dirt and corrosion. Good thing you rarely need the rear defogger! For what you will be spending for that kind of a sound system why are you trying to cheap out on all of the other necessary things to make it work?

[kobachi]

For what you will be spending for that kind of a sound system why are you trying to cheap out on all of the other necessary things to make it work?

I think you're making some assumptions about my "kind of sound system". Two 3.5"s, two 6x9s, an 8" sub and two 300W RMS amps to power it. Not exactly competition-level stuff :)

[Byrne H&A]

Checkout our alternators, 110A @ $149.00
See www.Deloreanupgradeparts.com

[DeLorean03]

I'm showing the replacement fan at $104 thru DeLorean.com. Is the Sieman's fan really that much cheaper? That's a big spread. Too big.

http://store.delorean.com/c-361-7-1-0-evaporator.aspx

Remember, Alex, that is the cost of a "plug-n-play" option. Most people want to do just that - buy the part, install, and GO.

[djdogbone]

Four seasons part (seiman) http://www.ebay.com/itm/35589-Four-Seasons-Reman-Blower-Motor-for-Buick-Chevy-GM-Olds-Pontiac-1977-85-86-/230629845988?pt=Motors_Car_Truck_Parts_Accessories&hash=item35b29c2be4&vxp=mtr

[Exolis]

Battery is capacitor, so there's no reason to buy a capacitor. If it's pulling too much, it's either a sign of a weak battery or alternator that cannot compensate. Any pop, whiny, etc noises heard in Audio system is typically an EMC issue. Would be nice if there were more modern alternators that could fit(whenever I have time, I plan on borrowing a few alternators from work to see if it fits on the DeLorean). It's really about who has the best Diodes to withstand heat and are quick.

[David T]

Battery is capacitor, so there's no reason to buy a capacitor. If it's pulling too much, it's either a sign of a weak battery or alternator that cannot compensate. Any pop, whiny, etc noises heard in Audio system is typically an EMC issue. Would be nice if there were more modern alternators that could fit(whenever I have time, I plan on borrowing a few alternators from work to see if it fits on the DeLorean). It's really about who has the best Diodes to withstand heat and are quick.

When you are working with DC unless you oversize the current carrying conductors (the wires) when you go to pull power during peaks in the music, especially when you are moving large bass speakers back and forth quickly, if the wires aren't big enough it doesn't matter how big the battery is. You just can't move enough current from the battery to the amp and then to the speakers quickly enough. Many set-ups use the caps for that purpose. They also do help with filtering, the DC in a car is very "noisy" because it is produced by an ALTERNATOR making AC. While it is true the alternator has diodes in it to create DC it is a very "dirty" DC. The battery is expected to "sink" and filter the peaks to get a smoother DC. That's theory, in practice an automobile is a VERY noisy environment for electronics. The source voltage varies, it is not pure DC, there are all kinds of spikes and surges impressed on it, etc. Then you have radio interference on top of all of that. Put a scope on an automobile's electrical system and see what you are feeding your equipment. Bulbs, switches, and electric motors aren't so picky but the more delicate stuff, radios, ECU's and stuff like that find it hard to live on that diet! I don't care how fast your diodes switch, they, by themselves, can't flatten out the waveform. As for sizing the battery and alternator, an alternator can't handle the full load under ALL conditions. During periods of low RPM's (like idling at a traffic light), when the alternator can't put out it's full rated output, the battery is expected to carry the load till the RPM's increase and the alternator can handle the load AND replenish the battery.

[Bill6298]

As for sizing the battery and alternator, an alternator can't handle the full load under ALL conditions. During periods of low RPM's (like idling at a traffic light), when the alternator can't put out it's full rated output, the battery is expected to carry the load till the RPM's increase and the alternator can handle the load AND replenish the battery.

Great info David. I'm beginning to think that I'm better off just running my Craig radio. The question is: don't I still need the 140A alternator? In the summer, idling at a traffic light, with the AC on MAX, and my typical aftermarket radio on a normal volume, my headlights were barely usable and the fans slowed down considerably. For those of us with a factory radio or basic aftermarket radios, do you recommend the 140A alternator? Earlier in the thread there were calculations of a stock DeLorean at over 90A.

FWIW and slightly off topic, I wonder if my car is too noisy for one of those giant battery-powered portable bluetooth speakers (like the Jambox (https://jawbone.com/speakers/bigjambox)). My audio is coming from my phone these days anyway. Seems like less hassle if that setup was actually usable.

[Bitsyncmaster]

When you are working with DC unless you oversize the current carrying conductors (the wires) when you go to pull power during peaks in the music, especially when you are moving large bass speakers back and forth quickly, if the wires aren't big enough it doesn't matter how big the battery is. You just can't move enough current from the battery to the amp and then to the speakers quickly enough. Many set-ups use the caps for that purpose. They also do help with filtering, the DC in a car is very "noisy" because it is produced by an ALTERNATOR making AC. While it is true the alternator has diodes in it to create DC it is a very "dirty" DC. The battery is expected to "sink" and filter the peaks to get a smoother DC. That's theory, in practice an automobile is a VERY noisy environment for electronics. The source voltage varies, it is not pure DC, there are all kinds of spikes and surges impressed on it, etc. Then you have radio interference on top of all of that. Put a scope on an automobile's electrical system and see what you are feeding your equipment. Bulbs, switches, and electric motors aren't so picky but the more delicate stuff, radios, ECU's and stuff like that find it hard to live on that diet! I don't care how fast your diodes switch, they, by themselves, can't flatten out the waveform. As for sizing the battery and alternator, an alternator can't handle the full load under ALL conditions. During periods of low RPM's (like idling at a traffic light), when the alternator can't put out it's full rated output, the battery is expected to carry the load till the RPM's increase and the alternator can handle the load AND replenish the battery.

True.

To get any benifit with a CAP, it needs to be wired close to the load. Even better is to power the CAP through a diode but then you are dropping a lot of power in that diode if your load current is high. I use a diode and cap in all my electronic designs but the current is low so I don't get a big power loss.

[David T]

True.

To get any benifit with a CAP, it needs to be wired close to the load. Even better is to power the CAP through a diode but then you are dropping a lot of power in that diode if your load current is high. I use a diode and cap in all my electronic designs but the current is low so I don't get a big power loss.

I agree the caps need to be close to the load to be of any use. I have no problem with the 140 amp alternator, just keep in mind it can't make all of those 140 amps at idle. If you are worrying about the alternator be sure to check the charging system to be sure all of the rest of it is working and test the battery. The Craig or the ASI radios are junk for making sounds. If you want them for originality that's one thing but for useable sounds I would replace or upgrade them. The speakers too.

[Exolis]

When you are working with DC unless you oversize the current carrying conductors (the wires) when you go to pull power during peaks in the music, especially when you are moving large bass speakers back and forth quickly, if the wires aren't big enough it doesn't matter how big the battery is. You just can't move enough current from the battery to the amp and then to the speakers quickly enough. Many set-ups use the caps for that purpose. They also do help with filtering, the DC in a car is very "noisy" because it is produced by an ALTERNATOR making AC. While it is true the alternator has diodes in it to create DC it is a very "dirty" DC. The battery is expected to "sink" and filter the peaks to get a smoother DC. That's theory, in practice an automobile is a VERY noisy environment for electronics. The source voltage varies, it is not pure DC, there are all kinds of spikes and surges impressed on it, etc. Then you have radio interference on top of all of that. Put a scope on an automobile's electrical system and see what you are feeding your equipment. Bulbs, switches, and electric motors aren't so picky but the more delicate stuff, radios, ECU's and stuff like that find it hard to live on that diet! I don't care how fast your diodes switch, they, by themselves, can't flatten out the waveform. As for sizing the battery and alternator, an alternator can't handle the full load under ALL conditions. During periods of low RPM's (like idling at a traffic light), when the alternator can't put out it's full rated output, the battery is expected to carry the load till the RPM's increase and the alternator can handle the load AND replenish the battery.

This is true, this actually covers quite a bit of what I do at Nissan. Some testing is to make sure all ECUs can handle that noise in the event a battery dies/disconnected while the car is running. I also work with EMC Test engineers and have learned quite a bit about Noise. While I agree, a Cap would help, but IMO the Battery and Audio Unit should be able to manage to rid of any noise that would cause popping, whines, etc.

[David T]

This is true, this actually covers quite a bit of what I do at Nissan. Some testing is to make sure all ECUs can handle that noise in the event a battery dies/disconnected while the car is running. I also work with EMC Test engineers and have learned quite a bit about Noise. While I agree, a Cap would help, but IMO the Battery and Audio Unit should be able to manage to rid of any noise that would cause popping, whines, etc.

Today's automotive electronics are MUCH better at handling the problems with source power than ever before. The ECU's and other sensitive equipment has a lot of built-in filtering to protect and compensate for the "dirty" DC then in years past. When you are talking about after-market electronics like radios, navigation, remote starters, alarms, and the rest you can have a LOT of problems. Much of it is made to a price-point and to do that they often do not include as much filtering and protection as they should. Buying cheap and then having to buy and install enough filtering to keep it from blowing up winds up costing more than buying the more expensive, better engineered and built product in the first place. Sometimes there is a good reason to pay more for a better product. Even with the best engineering in the world they still don't always get it right. A well publicized, recent example was the batteries catching fire on the Boeing Dreamliners! Another example is the shift computer for the automatic transmission. They couldn't follow the chip designer's recommendations for filtering and protection! It's a wonder they all didn't blow up! Guess the chips were better then the designers figured! I am not very familiar with the Flux Capacitor but it does have a LOT of caps! They are all over the rear of the BTTF car! I guess they need them for all of those jigawatts.

[kobachi]

So I ordered one of John Hervey's 120A alternators, on his advice against the 140A since I do a fair amount of city driving. I seem to remember seeing a pretty nice "DIY alternator replacement" guide at some point but I can't seem to find it now. Anyone have a link to that?

[Rich]

....I seem to remember seeing a pretty nice "DIY alternator replacement" guide at some point but I can't seem to find it now. Anyone have a link to that?

You are looking for an alternator replacement guide?

This one is in the Resources/How-To section of this forum:

LINK: http://dmctalk.org/showthread.php?47-How-To-Replace-an-alternator (http://dmctalk.org/showthread.php?47-How-To-Replace-an-alternator)

And there is also the Workshop Manual, sections M:04 and M:05

LINK: http://dmctalk.org/attachment.php?attachmentid=247&d=1306354550 (http://dmctalk.org/attachment.php?attachmentid=247&d=1306354550)

[Bill6298]

So I ordered one of John Hervey's 120A alternators, on his advice against the 140A since I do a fair amount of city driving. I seem to remember seeing a pretty nice "DIY alternator replacement" guide at some point but I can't seem to find it now. Anyone have a link to that?

What's the theory behind 120A alternator being better than the 140A?

[kobachi]

What's the theory behind 120A alternator being better than the 140A?

His 120A alternator is designed to put more current out at low engine speeds. He said stopped at a traffic light it should still put out 20-30A, whereas the 140A alternator (and most others) will only put out ~10A. At speed you're going to obviously get more current from the 140A, but I do enough city/traffic driving that the 120A was his recommendation. Since I'm not driving my amplifers at max power in the tiny DeLorean listening compartment, I think 120A will be just fine.

[kobachi]

Installed the D120 today. Took a little bit to figure out what the extra ring terminal attached to the body was for (apparently nothing). Works great -- in fact, I'm getting ~14.7V when the engine is idling, which seems a little high to me. Is this something to be concerned about?

I feel like I can hear a different whistling coming from the engine compartment -- maybe just the new belt breaking in. The engine also seems to be hunting less at idle.

[Bitsyncmaster]

Installed the D120 today. Took a little bit to figure out what the extra ring terminal attached to the body was for (apparently nothing). Works great -- in fact, I'm getting ~14.7V when the engine is idling, which seems a little high to me. Is this something to be concerned about?

I feel like I can hear a different whistling coming from the engine compartment -- maybe just the new belt breaking in. The engine also seems to be hunting less at idle.

You should hand spin the alternator (remove the belt) and not hear or feel any resistance to spinning. Try it both directions.

[Exolis]

Installed the D120 today. Took a little bit to figure out what the extra ring terminal attached to the body was for (apparently nothing). Works great -- in fact, I'm getting ~14.7V when the engine is idling, which seems a little high to me. Is this something to be concerned about?

I feel like I can hear a different whistling coming from the engine compartment -- maybe just the new belt breaking in. The engine also seems to be hunting less at idle.

14.7V is fine, it also means the Battery is well charged and not many loads are on, as well as the Alternator is running at a cooler temp.

[aipri]

Installed the D120 today. Took a little bit to figure out what the extra ring terminal attached to the body was for (apparently nothing). Works great -- in fact, I'm getting ~14.7V when the engine is idling, which seems a little high to me. Is this something to be concerned about?

I feel like I can hear a different whistling coming from the engine compartment -- maybe just the new belt breaking in. The engine also seems to be hunting less at idle.


What was the cost of that alternator? There is no price on Hervey's site for some reason. Also was it plug and play like the DMCH one or did you have to make any modifications? I am in the same situation you were in so I am quite interested in your experience with everything.

[kobachi]

What was the cost of that alternator? There is no price on Hervey's site for some reason. Also was it plug and play like the DMCH one or did you have to make any modifications? I am in the same situation you were in so I am quite interested in your experience with everything.

$160 for the D120. The browsing area of the site is borked but if you use the search function for 'alternator' you can add one to your cart and place an order. I've never seen the DMCH 140A alternator, but this one was more-or-less plug and play, no dremeling or anything like that.

You have to cut the terminal on the brown/white wire and wire it up to a connector that comes with the D120. And since you're replacing the belt too, it's a lot more work than the 20 minutes that was quoted to me on this site (took more like 2 hours with the help of a friend). But it's not hard to figure out. Just a lot of futzing around upside down.

It comes with a new mounting bolt, along with an extra nut that acts as a spacer. One thing I neglected to do was clean and rough up the mounting bracket, which provides the ground to the alternator (DMCNW pointed this out to me later). But mine works fine, and it includes a bolt and a ring terminal for adding a ground wire if you need one.