Alternator voltage question - Bosch
Former Vendor
Joined: Feb 2010
Posts: 1,803
Likes: 6
Seriously, though, we just sell DC Power's alternators. They have an amazing product that we are able to offer at a slight cost break than if you were purchasing them directly from DC Power's own web site.
For the next two weeks or so, orders taken by us will continue to be drop-shipped from the DC Power facility in California. About the middle of the month, though, we'll begin being a stocking distributor for them. Upshot: You order an alternator and it will be shipped SAME DAY and from a central location.
Hope this helps!
Ed
Thread Starter
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Postmaster
Joined: Jan 2009
Posts: 2,544
Likes: 4
From: Suffolk, VA
My batteries are fairly new and in good health. I have no charging issues or starting issues. Everything is in good health and my truck needs nothing; it's better than when it left the lot.
I've been following some of the alternator threads lately and doing some checking of my own and found this on the first cold start each day:
Battery volts - 12.4
Glow plugs on - 11.5-11.6
Engine cranking - 10.5-10.6 (just for a split second).
Cold idle (glow plugs on) - 12.0
cold Idle (glow plugs off) - 13.9-14.0
Hot idle (accessories on) - 13.5
I've been following some of the alternator threads lately and doing some checking of my own and found this on the first cold start each day:
Battery volts - 12.4
Glow plugs on - 11.5-11.6
Engine cranking - 10.5-10.6 (just for a split second).
Cold idle (glow plugs on) - 12.0
cold Idle (glow plugs off) - 13.9-14.0
Hot idle (accessories on) - 13.5
Batteries - 12.4
Glow plugs on -11.5-11.6
Engine Cranking - 10.6
Cold idle (GPs on) - 11.8 - 12.0
Cold Idle (GPs off) - 13.8-13.9
Hot idle - 13.8
Hot idle (accessories on) - 13.7
I'm sure it's a good alternator and would fit the bill to replace a dead alternator. But I don't think it is any good if you are looking for an upgrade. I guess that's what a lot of you have already said before. I was hoping to not spend $300 on a bigger alternator.
Former Vendor
Joined: Feb 2010
Posts: 1,803
Likes: 6
I installed the Bosch AL7606N today and am unimpressed. I don't know if Amazon will take it back or not but I'm going to try. My original 178,000 alternator is as good and I'll probably just put it back on for now. The only thing I see better on the Bosch 140 amp is that at hot idle with accessories on, it holds slightly higher volts. At speed on the roadway, it is no better. It looks worse at idle with no accessories, and with glow plugs on.
Batteries - 12.4
Glow plugs on -11.5-11.6
Engine Cranking - 10.6
Cold idle (GPs on) - 11.8 - 12.0
Cold Idle (GPs off) - 13.8-13.9
Hot idle - 13.8
Hot idle (accessories on) - 13.7
I'm sure it's a good alternator and would fit the bill to replace a dead alternator. But I don't think it is any good if you are looking for an upgrade. I guess that's what a lot of you have already said before. I was hoping to not spend $300 on a bigger alternator.
Batteries - 12.4
Glow plugs on -11.5-11.6
Engine Cranking - 10.6
Cold idle (GPs on) - 11.8 - 12.0
Cold Idle (GPs off) - 13.8-13.9
Hot idle - 13.8
Hot idle (accessories on) - 13.7
I'm sure it's a good alternator and would fit the bill to replace a dead alternator. But I don't think it is any good if you are looking for an upgrade. I guess that's what a lot of you have already said before. I was hoping to not spend $300 on a bigger alternator.
That said, before you throw in the towel on this one, have you considered installing an additional, fuse-protected wire from the back stud of the alternator to the passenger side battery along with another wire for ground? Perhaps your issue is just voltage drop.
Fleet Owner
Joined: Mar 2003
Posts: 24,724
Likes: 74
From: Blue Hill Township
I installed the Bosch AL7606N today and am unimpressed. I don't know if Amazon will take it back or not but I'm going to try. My original 178,000 alternator is as good and I'll probably just put it back on for now. The only thing I see better on the Bosch 140 amp is that at hot idle with accessories on, it holds slightly higher volts. At speed on the roadway, it is no better. It looks worse at idle with no accessories, and with glow plugs on.
Batteries - 12.4
Glow plugs on -11.5-11.6
Engine Cranking - 10.6
Cold idle (GPs on) - 11.8 - 12.0
Cold Idle (GPs off) - 13.8-13.9
Hot idle - 13.8
Hot idle (accessories on) - 13.7
I'm sure it's a good alternator and would fit the bill to replace a dead alternator. But I don't think it is any good if you are looking for an upgrade. I guess that's what a lot of you have already said before. I was hoping to not spend $300 on a bigger alternator.
Sent from my Telegraph using IB AutoGroup
Fleet Owner
Joined: Nov 2003
Posts: 27,929
Likes: 3,651
There are certainly less expensive alternator options than the $300+ that you'll spend for the DC Power units, but the trouble is that they consistently prove themselves to be cheaper.
That said, before you throw in the towel on this one, have you considered installing an additional, fuse-protected wire from the back stud of the alternator to the passenger side battery along with another wire for ground? Perhaps your issue is just voltage drop.
That said, before you throw in the towel on this one, have you considered installing an additional, fuse-protected wire from the back stud of the alternator to the passenger side battery along with another wire for ground? Perhaps your issue is just voltage drop.
I will say that their customer service has not been the best, but you (Ed) have filled that gap VERY nicely!
Thread Starter
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Postmaster
Joined: Jan 2009
Posts: 2,544
Likes: 4
From: Suffolk, VA
All good info, thanks. Ed, I will consider doing that and giving it a shot, I believe I have some 4 gauge cable laying around but will have to find the correct ring terminals.
I wasn't expecting the performance of a 250 amp alternator, but I was hoping to see an improvement at cold idle when the GPs were on. It sucks seeing voltage drop to 12 volts and below. I might give that overdrive pulley a shot because when it sees just a couple hundred more rpms the voltage shoots right up. I'm trying to determine if that would require a new shorter belt or not. I just replaced the belt and am not interested in the expense of doing that again.
I wasn't expecting the performance of a 250 amp alternator, but I was hoping to see an improvement at cold idle when the GPs were on. It sucks seeing voltage drop to 12 volts and below. I might give that overdrive pulley a shot because when it sees just a couple hundred more rpms the voltage shoots right up. I'm trying to determine if that would require a new shorter belt or not. I just replaced the belt and am not interested in the expense of doing that again.
Fleet Owner
Joined: Mar 2003
Posts: 24,724
Likes: 74
From: Blue Hill Township
All good info, thanks. Ed, I will consider doing that and giving it a shot, I believe I have some 4 gauge cable laying around but will have to find the correct ring terminals.
I wasn't expecting the performance of a 250 amp alternator, but I was hoping to see an improvement at cold idle when the GPs were on. It sucks seeing voltage drop to 12 volts and below. I might give that overdrive pulley a shot because when it sees just a couple hundred more rpms the voltage shoots right up. I'm trying to determine if that would require a new shorter belt or not. I just replaced the belt and am not interested in the expense of doing that again.
I wasn't expecting the performance of a 250 amp alternator, but I was hoping to see an improvement at cold idle when the GPs were on. It sucks seeing voltage drop to 12 volts and below. I might give that overdrive pulley a shot because when it sees just a couple hundred more rpms the voltage shoots right up. I'm trying to determine if that would require a new shorter belt or not. I just replaced the belt and am not interested in the expense of doing that again.
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Fleet Owner
Joined: Mar 2003
Posts: 24,724
Likes: 74
From: Blue Hill Township
This was a hot start. The truck was up to temp and I had moved it twice briefly before doing this. The lights and blower were not on. You can see the alternator is putting out ~220 amps at initial start and then it drops to ~180 and then tapers off to ~120. When the glow plugs turn off it settles in at ~35 amps. I'll still try to get one in the morning. My laptop with the Fluke software is at work so these screen shots will have to do for now.
Former Vendor
Joined: Feb 2010
Posts: 1,803
Likes: 6
These results are the reason I chose DC Power's 270XP for my own 6.0. DC Power's units consistently out perform their rated abilities and I wanted a unit that put out 200 amps at cold idle minimum (the 270 unit's rating) so that I wasn't stressing out my FICM for longer that I had to (during cranking) and didn't have to think twice about running the heated seats right after start up (when the glow plugs are still running) either.
Excellent post!
Re: DC Power's customer service. Thank you. I have tried diligently to keep their units in stock at their facility for my customers, but am looking forward to being a fully stocking distributor in the next couple weeks so that the units can ship directly from my shop.
Excellent post!
Re: DC Power's customer service. Thank you. I have tried diligently to keep their units in stock at their facility for my customers, but am looking forward to being a fully stocking distributor in the next couple weeks so that the units can ship directly from my shop.
Lead Driver
Joined: Sep 2012
Posts: 7,836
Likes: 96
From: Manteca,Ca
These results are the reason I chose DC Power's 270XP for my own 6.0. DC Power's units consistently out perform their rated abilities and I wanted a unit that put out 200 amps at cold idle minimum (the 270 unit's rating) so that I wasn't stressing out my FICM for longer that I had to (during cranking) and didn't have to think twice about running the heated seats right after start up (when the glow plugs are still running) either.
Excellent post!
Re: DC Power's customer service. Thank you. I have tried diligently to keep their units in stock at their facility for my customers, but am looking forward to being a fully stocking distributor in the next couple weeks so that the units can ship directly from my shop.
Excellent post!
Re: DC Power's customer service. Thank you. I have tried diligently to keep their units in stock at their facility for my customers, but am looking forward to being a fully stocking distributor in the next couple weeks so that the units can ship directly from my shop.
FTE Leadership Emeritus
Joined: Sep 2003
Posts: 12,258
Likes: 771
From: Houston, Texas
I just added a separate charging wire for my truck and it was more than able to maintain a consistent 13.5 volts at the OBDII with the front and rear A/C, lights, and fog lights on. Whereas before it would occasionally drop down to 12.0 and 12.5+ Volts with the a/c and all the lights on.
I'll keep an eye on it, but the additional, larger line does much better than the dinky one Ford put in.
I'll keep an eye on it, but the additional, larger line does much better than the dinky one Ford put in.
Lead Driver
Joined: Jul 2004
Posts: 6,952
Likes: 512
From: Foothills, CA
I just added a separate charging wire for my truck and it was more than able to maintain a consistent 13.5 volts at the OBDII with the front and rear A/C, lights, and fog lights on. Whereas before it would occasionally drop down to 12.0 and 12.5+ Volts with the a/c and all the lights on.
I'll keep an eye on it, but the additional, larger line does much better than the dinky one Ford put in.
I'll keep an eye on it, but the additional, larger line does much better than the dinky one Ford put in.
Thanks!
Former Vendor
Joined: Feb 2010
Posts: 1,803
Likes: 6
The factory wiring at the back of the alternator can only transfer so much amperage before voltage is lost. The more amperage to be flowed, the more voltage is lost during the transfer. The longer the wire, the more voltage is lost.
If you have an alternator with a voltage regulator with a 14.9 volt set point, but it is trying to dish out 200 amps, that 200 amp push at 14.9 volts won't end up at the destination as 14.9 volts, but some number less. If you had, say 10% voltage drop, that 14.9 would end up as 13.41 volts - not awesome.
By attaching an additional wire onto the back of the alternator, you provide the electrons an alternate course to reach their destination and by so doing make their lives easier. The result? Less voltage drop.
If by adding a wire to the back of that alternator, your voltage drop plummeted to only 1%, now the 14.9 volts would arrive as 14.75 volts.
Google 'voltage drop calculator' to play what if games with different sizes of wire, using the maximum amperage outlet of your alternator as the base amperage to transfer.
Hope this helps!
If you have an alternator with a voltage regulator with a 14.9 volt set point, but it is trying to dish out 200 amps, that 200 amp push at 14.9 volts won't end up at the destination as 14.9 volts, but some number less. If you had, say 10% voltage drop, that 14.9 would end up as 13.41 volts - not awesome.
By attaching an additional wire onto the back of the alternator, you provide the electrons an alternate course to reach their destination and by so doing make their lives easier. The result? Less voltage drop.
If by adding a wire to the back of that alternator, your voltage drop plummeted to only 1%, now the 14.9 volts would arrive as 14.75 volts.
Google 'voltage drop calculator' to play what if games with different sizes of wire, using the maximum amperage outlet of your alternator as the base amperage to transfer.
Hope this helps!