Are these Voltage readings OK? Considering Alternator Upgrade?

[clx16]

I put a tundra alternator in mine (130amp), and it has a smaller pulley. Photoman has a posting somewhere from some tests he's run that shows the voltage impact of the smaller pulley. I haven't replicated the test. I read my voltage in two places, one from the OBDII read out and another from a Voltmeter running from the ACC power to the sig lighter outlet. They aren't the same as OBDII usually says 13.7 - 14.4 and the other one usually says 13.3-13.7. I can also look at what my solar charge controller reads when the vehicle is off and it is 12.7 almost always. (it is in the back of the vehicle and zero gauge and six gauge wire over a long run with a fuse probably cause some voltage drop. I have an AGM battery. All other wiring is stock. Something i've noticed is on cold days the voltage runs high at first and settles in while driving. this happens on Hot days too, but it isn't as high and it settles in faster. I can't compare with an 80amp as mine died and that was the reason for the upgrade.

I know this probably doesn't help you but I thought the information might give you something to compare. I don't run a ton of accessories... yet.

 

[Cruiserdrew]

Just measure your amp draw. It's usually easiest at the ground terminal. Your wild card is the 100 amp (is it really that much?) fan, which takes you far above stock requirements.

I'm in the camp that the NEED to upgrade is rare. But a continuous high amp draw when running IS the reason to use a higher output alternator.

Just remember, when the truck isn't running, the 150 amp alternator is doing nothing for you. So only if you need more power when the engine is running do you need a higher amp alternator. So huge lights, monster stereo, or a huge draw from a fan may require more power from the alternator. But you have to measure to know.

I'd also be sure your wiring is up to date (often smart to up size the wire from the alternator B terminal to the battery +) and check all the ground connections and clean them down to bright metal.

And BTW-stock the 80 series alternator is rated at 90 amps. And my 3FE's alternator is rated at 80 amps and actually makes 86 amps when tested. I'd be curious to hear how your alternator tests out, but you'll need to go to a real auto electrical place to know.

 

[Dissent]

I'd like to see what you're including to come up with a 200A draw.

The categories on that calculator are far too vague to be of any use. Easiest way is to use a DC clamp meter with the engine idled up.

It's on the list...just need to dig one up.

I clicked 1995 and later car, A/C, Halogen headlights, 1x aux fan, 500W amplifier, 1x air compressor and TV/DVD. Again...it's a ballpark. I suspect I need about 100A at idle.

 

[Dissent]

[QUOTE="Dissent, post: 11697017, member: 81471]"Keep in mind, it's a rough calculator.

This is a rough forum sometimes. I see a lot of push back to upgrade the charging system. Everything else on these trucks is upgraded as a matter of fact, usually to the point of exceeding ANY real world requirement. I'm not sure why 2+ batteries is blessed by all, primarily for winching, but a larger alternator for daily loads and drive-ability is met with blank stares and mutterings about one's mental stability. I realize that many 80 owners don't have any additional current draw but some do. I've moved this Alpine amp around the past 3 vehicles, all had 150A alternators and never had any issues. Now I've added a cooling fan for the radiator. I also run my headlights all the time for visibility. I also have to run my A/C and headlights and wipers at night during the summer. There are real world requirements that push the demand past the 40-50A OEM loads."

I agree with you. I don't understand the push-back. Its clear you need more output at idle. Before I replaced my headlight bulbs with LED I noticed my alternator couldn't keep up with the load if my AC or wipers are on. If a bulb could be replaced, I replaced it with LED. It helped a lot. I do have Photoman's 150amp conversion and a Denso 150A alternator waiting for my 80A alternator to crap the bed. I know that if I add any more load to the electrical system, which I will, it will require a higher output alternator to accommodate. Its pretty simple to figure that out. I think you're on the right track and 100% correct in your thinking.[/QUOTE]
Thank you. I'm curious to see how the Sequoia alternator works for you. I can't find any specs on what the idle speed output is on that alternator.

 

[Dissent]

I put a tundra alternator in mine (130amp), and it has a smaller pulley. Photoman has a posting somewhere from some tests he's run that shows the voltage impact of the smaller pulley. I haven't replicated the test. I read my voltage in two places, one from the OBDII read out and another from a Voltmeter running from the ACC power to the sig lighter outlet. They aren't the same as OBDII usually says 13.7 - 14.4 and the other one usually says 13.3-13.7. I can also look at what my solar charge controller reads when the vehicle is off and it is 12.7 almost always. (it is in the back of the vehicle and zero gauge and six gauge wire over a long run with a fuse probably cause some voltage drop. I have an AGM battery. All other wiring is stock. Something i've noticed is on cold days the voltage runs high at first and settles in while driving. this happens on Hot days too, but it isn't as high and it settles in faster. I can't compare with an 80amp as mine died and that was the reason for the upgrade.

I know this probably doesn't help you but I thought the information might give you something to compare. I don't run a ton of accessories... yet.

I have a very similar setup and similar readings...until I turn everything on and sit still.

 

[Dissent]

Just measure your amp draw. It's usually easiest at the ground terminal. Your wild card is the 100 amp (is it really that much?) fan, which takes you far above stock requirements.

I'm in the camp that the NEED to upgrade is rare. But a continuous high amp draw when running IS the reason to use a higher output alternator.

Just remember, when the truck isn't running, the 150 amp alternator is doing nothing for you. So only if you need more power when the engine is running do you need a higher amp alternator. So huge lights, monster stereo, or a huge draw from a fan may require more power from the alternator. But you have to measure to know.

I'd also be sure your wiring is up to date (often smart to up size the wire from the alternator B terminal to the battery +) and check all the ground connections and clean them down to bright metal.

And BTW-stock the 80 series alternator is rated at 90 amps. And my 3FE's alternator is rated at 80 amps and actually makes 86 amps when tested. I'd be curious to hear how your alternator tests out, but you'll need to go to a real auto electrical place to know.

Thanks for the info.
I don't have a 100A fan. I think it's rated between 5A-10A.
I don't care anything about when the truck isn't running. I have the battery to depend on for that. It's ALL about sitting idling or going very slow on a trail in 90+ degree heat for 6+ hours. Measuring is on the list when I get a clamp meter. My multi-meter only reads up to 500ma.
Wiring is beyond up to date...see the first post...that's why I listed all that data up front. I am quite possibly the most anal retentive person when it comes to wiring, ground, proper sizing, etc.
90A, good to know. Everything I've found says 80A, less the 80% brings it to 64A at 4000 RPM.
Improvements:

• Big 3 2AWG Cabling (225A rated) - Battery Ground to Frame, Battery Positive to Alternator, Alternator Ground to Battery

 

[Dissent]

More amps is better but still you’re not drawing 200A and probably a fresh 80a would bring you at least over 13v. Even my truck charges at 13v at idle and I’m planning on replacing the alternator ASAP.

The 200A was just a reference point from a 3rd party. I know I'm not drawing 200A. I really never claimed I was. I do know that I'm drawing more than the OEM alternator is putting out at idle because I'm into the battery, hence the 12.x voltage reading.
While I do appreciate the input from everyone. I did state in the first post that I had replaced the battery with an AGM biggie, then the alternator with a Toyota reman. then another new wet battery.
Are you running any of the accessories I'm describing at idle? (A/C, Amplifier, Aux Fan, Headlights, Wipers, etc.)

 

[Cruiserdrew]

What I have noticed about the voltage output of the alternator, is that it varies with temperature. When I first start up, I get 14.8 volts. (Assuming everything is mostly charged up). As it warms up, voltage drops to 14.0. If it's very hot, sometimes 13.8-13.9.

If you exceed your alternator output, voltage will drop fast to battery voltage immediately. Which in turn will sag with a load on it. My resting battery voltage is 12.7 even with the battery full. Even a small load will drop it into the 12.5-12.6 range, even though the state of charge is still basically 100%. Take the load off, it returns to 12.7. Normal. Note your battery voltage with a big load like your starter will momentarily sag to 11s somewhere but it doesn't mean its fully discharged, just the normal sag under load.

What I'm having trouble understanding is why you don't have enough alternator output. I have 2 batteries, 2 refrigerators, run A/C, lights, blower on high, Ham radio, idle down the trail and the alternator keeps up fine without an undue drop in voltage. I suspect your current(ha, pun alert) alternator is not putting out it's full output for some reason. Either that, or you have a mystery draw (and a big one) you need to sort out. Do you get the same readings if you measure the voltage at the battery with a DVM? What happens if you pull your amplifier power input?

And one correction to your test conditions report above:

Battery specific gravity is above 1.3v per cell

You probably mean 2.3. If it's 1.3, there's your problem! And SG is not measured in volts, but I know what you really mean-the specific gravity is indicating a full charge.

I don't think there is any "allegiance" on my part to the stock alternator. It's sufficient 99% of the time. But if your power demands are above what it can do, you should upgrade. But measure your loads. Maybe you need more than 150 amps! I promise you 99% of the people who run an upgraded alternator don't need it, and didn't do any measurements to see whether they did or didn't. They just wanted a bigger one. I'm down with that!

 

[Dissent]

What I have noticed about the voltage output of the alternator, is that it varies with temperature. When I first start up, I get 14.8 volts. (Assuming everything is mostly charged up). As it warms up, voltage drops to 14.0. If it's very hot, sometimes 13.8-13.9.

If you exceed your alternator output, voltage will drop fast to battery voltage immediately. Which in turn will sag with a load on it. My resting battery voltage is 12.7 even with the battery full. Even a small load will drop it into the 12.5-12.6 range, even though the state of charge is still basically 100%. Take the load off, it returns to 12.7. Normal. Note your battery voltage with a big load like your starter will momentarily sag to 11s somewhere but it doesn't mean its fully discharged, just the normal sag under load.

What I'm having trouble understanding is why you don't have enough alternator output. I have 2 batteries, 2 refrigerators, run A/C, lights, blower on high, Ham radio, idle down the trail and the alternator keeps up fine without an undue drop in voltage. I suspect your current(ha, pun alert) alternator is not putting out it's full output for some reason. Either that, or you have a mystery draw (and a big one) you need to sort out. Do you get the same readings if you measure the voltage at the battery with a DVM? What happens if you pull your amplifier power input?

And one correction to your test conditions report above:


You probably mean 2.3. If it's 1.3, there's your problem! And SG is not measured in volts, but I know what you really mean-the specific gravity is indicating a full charge.

I don't think there is any "allegiance" on my part to the stock alternator. It's sufficient 99% of the time. But if your power demands are above what it can do, you should upgrade. But measure your loads. Maybe you need more than 150 amps! I promise you 99% of the people who run an upgraded alternator don't need it, and didn't do any measurements to see whether they did or didn't. They just wanted a bigger one. I'm down with that!

Possibly not putting out the full rating, not sure. Don't really want to pull it to check, it's a major PITA. I'll try and measure the amp draw and report back. Have to buy a clamp meter first.

The hydrometer scaled maxed out at 1.3 and mine went a notch above. 1.4? The scale didn't go to 2.3.

 

[Cruiserdrew]

Got it, that's a real specific gravity reading. No units. Fully charged is 1.280. They are rounding up.

 

[Dissent]

I just installed a new Victron BMV-712 ammeter and discovered that my alternator is insufficient. As an aside, the Victron unit is awesome with built in Bluetooth. It shows readings in real time to a tenth of an amp.

Sitting at a light at idle with my normal load shows I'm deficient by 5-7 Amps which means there's not enough output at idle.

I turned on a bunch of stuff and managed to draw 87 Amps with the engine off. I charged the battery up with an external charger over night and ran the same test with the engine at 2000 RPM. This time it showed 27 Amps pulled from the battery. Looks like my alternators's max output ia about 60 Amps. Running the same load at idle showed about 85 Amps deficient as most all was drawn from the battery.

I have a 77K mileage 150A Sequoia Denso unit coming from a junkyard in a few days. Paid $150 with 3-year warranty. I have new OEM bearings and a brush assembly waiting for it. Looking forward to seeing how it changes my situation.

 

[Cruzerman]

I'm a big fan of having a good alternator. But I'm also a big fan of doing some analysis to see what the requirements actually are. Many people talk about "1000 watt" stereo amps and such. Often that is what I call "marketing watts" and only have 20 amp fuses in them. But arbitrarily picking a number like 200 amps for the alternator makes no sense to me.

I ran some big radio gear in my 60 series with a big alternator and many batteries in the rear. On that rig, there was space for big Leece Neville alternators. Now those are alternators!

 

[Dissent]

I'm a big fan of having a good alternator. But I'm also a big fan of doing some analysis to see what the requirements actually are. Many people talk about "1000 watt" stereo amps and such. Often that is what I call "marketing watts" and only have 20 amp fuses in them. But arbitrarily picking a number like 200 amps for the alternator makes no sense to me.

I ran some big radio gear in my 60 series with a big alternator and many batteries in the rear. On that rig, there was space for big Leece Neville alternators. Now those are alternators!

That is exactly what drew me to the Victron meter, and keeping any eye on the battery while camping. I wanted to ensure I knew my exact draw numbers and ensure I have the overhead to upgrade my amplifier and what not going forward. I'm very comfortable knowing now that I won't draw more than 87A with everything running. Oh, I did include the Puma compressor which kicked it up about 35A but that's on top of my normal load so it's all good. Even if I ran it with everything else, I'm still in the comfortable range of the 150A unit with 20% overhead at 122A.

 

[Dissent]

For the record, my starter pulls 150A, it's nice to be able to see true loads on the system in real time.

 

[Dissent]

[QUOTE="Dissent, post: 11697017, member: 81471]"Keep in mind, it's a rough calculator.

This is a rough forum sometimes. I see a lot of push back to upgrade the charging system. Everything else on these trucks is upgraded as a matter of fact, usually to the point of exceeding ANY real world requirement. I'm not sure why 2+ batteries is blessed by all, primarily for winching, but a larger alternator for daily loads and drive-ability is met with blank stares and mutterings about one's mental stability. I realize that many 80 owners don't have any additional current draw but some do. I've moved this Alpine amp around the past 3 vehicles, all had 150A alternators and never had any issues. Now I've added a cooling fan for the radiator. I also run my headlights all the time for visibility. I also have to run my A/C and headlights and wipers at night during the summer. There are real world requirements that push the demand past the 40-50A OEM loads."

I agree with you. I don't understand the push-back. Its clear you need more output at idle. Before I replaced my headlight bulbs with LED I noticed my alternator couldn't keep up with the load if my AC or wipers are on. If a bulb could be replaced, I replaced it with LED. It helped a lot. I do have Photoman's 150amp conversion and a Denso 150A alternator waiting for my 80A alternator to crap the bed. I know that if I add any more load to the electrical system, which I will, it will require a higher output alternator to accommodate. Its pretty simple to figure that out. I think you're on the right track and 100% correct in your thinking.[/QUOTE]
It's interesting to see that the HIR headlight bulbs on low pull 30A (EDIT 14.6A), I have some small LED cubes that boast 2000 lumen output and I was surprised to see they pull 23A (EDIT 7.9A).

 

[Cruzerman]

I think the 9012 HIR are 55 watt units and the 9011 HIR are 65 watt. Even if you have in two 9011 bulbs, that should be 130 watts which is only about 10 amps for both bulbs. If you use them for high beam as well, it should be around 20 amps for all four bulbs turned on. Something doesn't sound right with your measurements.

 

[Dissent]

I think the 9012 HIR are 55 watt units and the 9011 HIR are 65 watt. Even if you have in two 9011 bulbs, that should be 130 watts which is only about 10 amps for both bulbs. If you use them for high beam as well, it should be around 20 amps for all four bulbs turned on. Something doesn't sound right with your measurements.

Sorry, I edited that last post. I need to stop posting from memory...it's not that great.

Actual numbers I collected from everything this morning are below:

Key On, Nothing Else Powered On - 1.4A
LCP Radiator Fan - 6.8A
A/C Blower on High - 12.9A
Headlights Low - 14.6A
Headlights High - 24.2A
2x 2" Cube LED Spots - 7.9A
1x Side 11" LED Spot/Flood - 2.8A
2x Side 11" LED Spot/Flood - 5.7A
Front Wipers High - 6.5A (peak)
Red LED Dome Light - >.1A
Main LED Dome Light 2"x2" - >.1A
Aux Dual 2.1A USB port - >.1A
500W Alpine Amp Max Volume Pop Music - 18.6A
Pioneer Stereo - 1.5A
Driver's Window Down - 3.7A to 14.1A
Driver's Window Up - 7A to 13.3A
Door Locks Locked - .9A
Door Locks Unlocked - 2.1A

Daily Commute Load (Headlights, A/C, LCP Radiator Fan, Stereo/Amp) - 56A

 

[Cruzerman]

No worries. My memory isn't what it used to be either. At least I think it isn't.

You can throw out the transitory loads like windows up / down, door locks, etc. So, it looks like you could possibly be near 90A if you are driving with the high beams on, A/C on max, radiator fan, all the LED lights on, stereo at max, and wipers on high. If it were me, I wouldn't be rushing out to replace the alternator. But when it was time to replace it, I'd at least look into an upgrade.

 

[Dissent]

If I was highway driving all the time, I'd agree 100%. Unfortunately, the bulk of my driving is in 110 degrees in city traffic with a 56A load. Lots of sitting with low voltage, low A/C output and high A/C temps. As long as I'm holding it at 2000 RPMs at every stop light, everything works great.

The new Sequoia should take care of all the idle output issues.

 

[Dissent]

Installed my 150A Sequoia with @Photoman's small pulley and all my problems are fixed! It doesn't matter what I turn on, it shows 13.7V+ and 2A in 105 degrees at idle on my Victron monitor. It used to show about 12.2V -25A. I had my normal load on revved to 2000 RPM and not a bit of change on the AC blower. I even ran my Puma on top of this and it kept on trucking. I didn't get to test its output but that's nearly 95A at idle. I'm extremely satisfied and realized that from 1997 to 2007 had a huge difference in idle output. The Sequoua swap is now the first thing I would recommend to new 80 owners.