Higher output alternator?

jlach993

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Has anyone come across a better alternator than the stock Denso 150amp OEM one? I've seen 250amp ones at 1.5k rpm for the LR3, but nothing solid for the LR4. There is one company that makes a 240 and 320amp alternator for the LR4. I'm really skeptical of them and think that their alternators only make that amperage at like 6k rpm which is useless to me. I tried messaging them as well with no response which makes me feel even more skeptical. I have many electrical add ons and a killer 2000 watt audio system (upgraded speakers and tweeters on its own aftermarket amp and 2 15inch subs on its own amp). With all of them working at the same time, my battery voltage dips to 11.3 when running...not good. I did the wiring upgrade already going from the alt to the battery and beefed up the ground cable, but i think the OEM alt is just not up to the job. When using the front windshield heater especially, the entire truck lights dim and the engine idle dips as well briefly. When everything is turned off and the truck idles i get about 14.5 with the stock alternator, so it's definitely underpowered. Any ideas people? thanks!
 

djkaosone

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When I was heavy into the audio scene back in the 90s, high output alternators were stupid expensive. As kids, we used 1 Farad capacitors as a buffer. Technology has definitely come a long way since then, but the mentality is the same.

Honestly, I wouldn't change the alternator due to our complex PWM charging system. You might have more issues down the road. Electronics are stupid finicky on these trucks. That leads into getting a buffer of some sort, like capacitors or dedicated audio battery bank(s).

To me, capacitors will do a few things better in these trucks. It'll stabilize your entire electrical system, doesn't require a dc-dc charger to charge a battery bank, and it doesn't require a battery isolator.

Damn, I think I might add a capacitor for the heck of it to stabilize my electrical system. Thanks for bringing up this topic!
 

mbw

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I also wish we had a water cooled option. The stupid alternator is so low that it can get filled with junk pretty quick. I'd also take a higher output one to run my 50 amp redarc DCDC and keep my winch happy during big pulls.
 

TrinidadLR4

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The PWM system sure is interesting. I got a new alternator put in as part of the engine transplant and since then, it has been showing 14.7 when driving. However, last week I noticed that while on the road, it would dip to 12.2-12.4 for 5-10 minutes at a time. That's normal PWM behavior right? Battery is less than a year old.
 

jlach993

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When I was heavy into the audio scene back in the 90s, high output alternators were stupid expensive. As kids, we used 1 Farad capacitors as a buffer. Technology has definitely come a long way since then, but the mentality is the same.

Honestly, I wouldn't change the alternator due to our complex PWM charging system. You might have more issues down the road. Electronics are stupid finicky on these trucks. That leads into getting a buffer of some sort, like capacitors or dedicated audio battery bank(s).

To me, capacitors will do a few things better in these trucks. It'll stabilize your entire electrical system, doesn't require a dc-dc charger to charge a battery bank, and it doesn't require a battery isolator.

Damn, I think I might add a capacitor for the heck of it to stabilize my electrical system. Thanks for bringing up this topic!
Thanks for the input dude. I did think about adding a capacitor, but figured an upgraded alt would've worked best. Since you put it that way along with the lack of high output alts for these trucks, ill deff be going to capacitor route. Maybe a second battery as well in case i ever do **** off the primary one. I tend to play music with the truck off in the summer when its parked in my garage and I'm doing work in my garage. Sometimes i do have the battery connected to a trickle charge in those situations, but i am lazy at times and just run the music off the battery.
 

jlach993

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The PWM system sure is interesting. I got a new alternator put in as part of the engine transplant and since then, it has been showing 14.7 when driving. However, last week I noticed that while on the road, it would dip to 12.2-12.4 for 5-10 minutes at a time. That's normal PWM behavior right? Battery is less than a year old.
uhm so from cold start my truck jumps to 14.6 volts. After about a few minutes of driving it goes down to 13.7. It stays there until I use my front windshield heaters of defoggers. Once those kick on I see voltage at 12.2. The voltage goes up back to 13.7 once I'm driving at 1/2 throttle at 2.5k rpm usually. Then once I slow down it goes down back to 12.2. With those heaters and defoggers off I get 13.7 with normal driving and at idle. If I'm playing music that's bass heavy it varies between 12.5-13.7 for a few seconds here and there, but that's because of the music and its understandable. The damn smart alternator has some crazy algorithm I could never understand. 13.7 barely would charge my battery. I do not get starting issues but i get low battery messages with the car off after like 15 mins. That is not normal. Its because the battery isn't getting above 14 volts. I know the alt lowers volt going to the battery under heavy engine load to save on gas, but how much of a savings is that really? I wish there was a way to disable that smart alt function and let the alternator give a healthy 14+ volt.....unplugging the battery and resetting the electronics makes the truck run at 14.6 volts at all times for a few days. I'm sure you're aware of all of this anyways @TrinidadLR4 , you're pretty knowledgeable in regards to these trucks.
 

djkaosone

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The PWM system sure is interesting. I got a new alternator put in as part of the engine transplant and since then, it has been showing 14.7 when driving. However, last week I noticed that while on the road, it would dip to 12.2-12.4 for 5-10 minutes at a time. That's normal PWM behavior right? Battery is less than a year old.
Yup, unfortunately, that's 100% normal. With the PWM system it does this to "save" your battery from overcharging and prematurely failing. I find it quite the opposite, I digress. Even though the volts dip, the alternator is actually putting out the proper amperage to maintain your electrical needs in realtime. I seriously monitored this on my Gap IID Tool over the course of 2 months, with the last couple weeks being every now and then.

Another way to test is to simply unplug the bms plug on the negative post, and you should see a steady 13.8V with a +/- 0.2V variable. Anything more or less, means that your alternator might be having issues and should be tested further.
 

gabrielef

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Too bad the Power Bastards 250A won’t work, that’s what I have in my LR3 and ALL issues related to “not enough power” are gone. No more dimming lights when running music and air conditioning.
 

drivesafe

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Another way to test is to simply unplug the bms plug on the negative post, and you should see a steady 13.8V with a +/- 0.2V variable. Anything more or less, means that your alternator might be having issues and should be tested further.
Hi djkaosne, have you tried this yourself and if so for how long?

If you have done this, did you get any error messages?

I am experimenting with charging a lithium auxiliary battery direct from the alternator ( via an isolator ) and while I can do this on some vehicles, I have not yet succeeded on a D3 ( LR3 ) or D4 ( LR4 ).
 

gabrielef

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Hi djkaosne, have you tried this yourself and if so for how long?

If you have done this, did you get any error messages?

I am experimenting with charging a lithium auxiliary battery direct from the alternator ( via an isolator ) and while I can do this on some vehicles, I have not yet succeeded on a D3 ( LR3 ) or D4 ( LR4 ).
I would not charge a LiFePo battery directly from the alternator. It needs a very specific charging profile around 14.6V. Better to get a Renogy or similar DCDC charger, or similar, with a specific charging profile. I just purchased a RedArc 1240D for this specific task in my LR4. Also connecting a hood mounted solar panel from Lensun to keep it charged. The LR4 is such a power hungry girl haha.
 

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