mc71
Junior Member
Ever since I had my Mechman 240a installed (Nov 2014), a quick 16+v voltage spike occurs when I accelerate after idling (at traffic lights & stop signs). It throws my amps into protect mode a few seconds…mostly my AB 4480.1. The heater blower quickly surges, any dome lights on quickly flash brighter, etc. Once I’m in motion driving, the voltage stays around mid-14v, idling is around 12.8-13.5v, but if I'm sitting at a stop light or intersection, then step on the gas, the voltage jumps, my sub amp cuts out (occasionally my 4-channel amp too). The gains can be turned down, the amps can even be disconnected & I'll still see the spike with a DMM on the amp cable (currently I just keep a volt-meter plugged in my cigarette lighter).*
My battery keeps a good charge 12.8v (13.1v after a full recharge). My wiring & connections are solid. I've switched back in an old sub amp & same thing happens (w that amp, the cut out time is shorter but still..). Sometimes if I accelerate slowly I can keep it from spiking, but that gets more difficult once the car warms up.*
I've taken my car back to the shop that installed it (Mercury Mariner alts aren’t an average diy install) to check connections, belt slipping etc. And 2 other shops specializing in electric, they both ran tests & said the alt “seems” to be ok (one shop mentioned "though it idles low"). Both shops saw the 16+v spikes on their tests & said (paraphrasing) "it happens for a millisecond, then the PCM takes over….it just doesn’t catch the first millisecond” *
Mechman response:
"PCM controlled*Ford systems cannot respond quickly enough to the radical change in output (due to the unit being a high output piece) as you accelerate the engine.*This is a common occurrence with any PCM controlled Ford unit. *The spikes should be brief enough that they do not damage any electrical equipment in*the vehicle. *You can also add more battery capacity to reduce the amplitude of the spike. *Usually it is only noticeable on vehicles with small battery*banks and high capacity alternators."*
[While that nugget of info is helpful AFTER my purchase.....if the PCM ultimately regulates the voltage, why put regulators in an alternator custom-built for that car? And why would those regulators EVER let the alt produce 16+ volts? (surely the PCM isn't requesting it).]*
I don't know if it matters that my overall voltage meter level also constantly changes...…much, much more than when I plug my meter in a friend’s (oem) car. His voltage almost never changes & stays in the 14.1-14.2v range. Mine constantly changes, usually averaging around 14.3 on the highway, but still constantly changing, sometimes anywhere from 11.8-15.5v, certainly when pumping music….but even when idling w no power accessories on. The shops don’t seem too alarmed by this so I’m not getting too uppity about it. I’ve sent video clips of my volt meter to Mechman & they’re not too alarmed either. Just thought I’d mention. I can post the clips if needed.
Mechman offered to have me send it back for them to test. But like I mentioned, Mariner alt install ain’t that easy. It's located under the car, buried behind other parts, youtube tutorials call the swap a “pain in the ass”. Just having the Mechman installed (also upgrading cables) was $500. Now the lowest quote to swap it out is $300 (so aka $600 to have a $349 alternator sent in for repair).*
Neither shop tested the actual internal regulators/diodes…..they probably could, for another $300 + bench testing time. But briefly describing my issue to various people with various level of car knowledge (not necessarily with HO alts) has certainly been met with “sounds like a bad regulator” more than once.
So now I don't know what to do, I’m considering several options but can’t decide which is best (if any)
1. Buy 2 new batteries. I currently have an XS Power D4800 (815 ca) purchased 6-7 months ago, it's the only model their website says fits my car, for what that's worth. It’s rated for systems up to 3000W (both amps’ RMS would be under that….their fusing = 170amps). Ordering 2 (to be identical same-age) D4800's is roughly $600. *
Btw, I recently tried an odd dual-battery experiment adding a spare AutoCraft Gold battery (745ca) to the D4800 (815ca). The AutoCraft was brand new & the D4800 was fully charged, so I figured at least I'd try hooking them both up for a test (then unhooking right after). It initially worked & stopped my sub amp from cutting out...but after I drove the car a while, it would eventually cut out again if I wasn't gentle while accelerating. I realize the AutoCraft battery isn't big & heavy like the XS Power...but since they both have semi-similar "ca" values, part of me wonders if even 2 D4800’s would be less than 100% reliable solving this problem.
(I barely want to mention that I own a Precision Power 10F capacitor….it’s not hooked up….it didn’t stop the amp's protect mode when I tried it. But I’m thinking about hooking up the 2 batteries again & adding the cap as well, just to experiment. I’ve read that more "separate" power banks are better for smoothing out voltage. But just $.02, I did sorta think the sound seemed more “present” when I had the cap hooked up.)
2. Get a different alternator. I emailed Michael Singer about my problem (which he seemed familiar with) & he mentioned building me a "6-phase design, voltage regulator w twin rectifiers, high pole count rotor, 2 stators". Could this build make a difference? (assuming the Mechman alt is working as “expected”)? *I don't know much about alternator parts at all. But certainly*before I spend $600 swapping alternators, I'll just buy a different alternator & swap once.
3. Change amplifiers (to analog....mine are both hybrids). I'm wondering if digital/hybrid amps are more sensitive than analog. They sound better than my old Alpine amps (which sounded good) but my analog MRP-F250 never cut out during the spikes. My current amps match my drivers well (still wanting 1 more JBL mkii to run the 4480.1 at .75 ohms). Ultimately I know I shouldn't have to switch them & I'd always worry about popping subs.
4. Tweak PCM software (increase idle speed). Seems like a huge challenge if even possible.
5. Smaller pulley (although as the shop that mentioned the idea said "it's already pretty small"). I doubt this is the answer too.
I'm so tired of turning down my music at every stop light (& I live in a downtown area)...
Any input would be appreciated.
(Sorry for the post length)
My battery keeps a good charge 12.8v (13.1v after a full recharge). My wiring & connections are solid. I've switched back in an old sub amp & same thing happens (w that amp, the cut out time is shorter but still..). Sometimes if I accelerate slowly I can keep it from spiking, but that gets more difficult once the car warms up.*
I've taken my car back to the shop that installed it (Mercury Mariner alts aren’t an average diy install) to check connections, belt slipping etc. And 2 other shops specializing in electric, they both ran tests & said the alt “seems” to be ok (one shop mentioned "though it idles low"). Both shops saw the 16+v spikes on their tests & said (paraphrasing) "it happens for a millisecond, then the PCM takes over….it just doesn’t catch the first millisecond” *
Mechman response:
"PCM controlled*Ford systems cannot respond quickly enough to the radical change in output (due to the unit being a high output piece) as you accelerate the engine.*This is a common occurrence with any PCM controlled Ford unit. *The spikes should be brief enough that they do not damage any electrical equipment in*the vehicle. *You can also add more battery capacity to reduce the amplitude of the spike. *Usually it is only noticeable on vehicles with small battery*banks and high capacity alternators."*
[While that nugget of info is helpful AFTER my purchase.....if the PCM ultimately regulates the voltage, why put regulators in an alternator custom-built for that car? And why would those regulators EVER let the alt produce 16+ volts? (surely the PCM isn't requesting it).]*
I don't know if it matters that my overall voltage meter level also constantly changes...…much, much more than when I plug my meter in a friend’s (oem) car. His voltage almost never changes & stays in the 14.1-14.2v range. Mine constantly changes, usually averaging around 14.3 on the highway, but still constantly changing, sometimes anywhere from 11.8-15.5v, certainly when pumping music….but even when idling w no power accessories on. The shops don’t seem too alarmed by this so I’m not getting too uppity about it. I’ve sent video clips of my volt meter to Mechman & they’re not too alarmed either. Just thought I’d mention. I can post the clips if needed.
Mechman offered to have me send it back for them to test. But like I mentioned, Mariner alt install ain’t that easy. It's located under the car, buried behind other parts, youtube tutorials call the swap a “pain in the ass”. Just having the Mechman installed (also upgrading cables) was $500. Now the lowest quote to swap it out is $300 (so aka $600 to have a $349 alternator sent in for repair).*
Neither shop tested the actual internal regulators/diodes…..they probably could, for another $300 + bench testing time. But briefly describing my issue to various people with various level of car knowledge (not necessarily with HO alts) has certainly been met with “sounds like a bad regulator” more than once.
So now I don't know what to do, I’m considering several options but can’t decide which is best (if any)
1. Buy 2 new batteries. I currently have an XS Power D4800 (815 ca) purchased 6-7 months ago, it's the only model their website says fits my car, for what that's worth. It’s rated for systems up to 3000W (both amps’ RMS would be under that….their fusing = 170amps). Ordering 2 (to be identical same-age) D4800's is roughly $600. *
Btw, I recently tried an odd dual-battery experiment adding a spare AutoCraft Gold battery (745ca) to the D4800 (815ca). The AutoCraft was brand new & the D4800 was fully charged, so I figured at least I'd try hooking them both up for a test (then unhooking right after). It initially worked & stopped my sub amp from cutting out...but after I drove the car a while, it would eventually cut out again if I wasn't gentle while accelerating. I realize the AutoCraft battery isn't big & heavy like the XS Power...but since they both have semi-similar "ca" values, part of me wonders if even 2 D4800’s would be less than 100% reliable solving this problem.
(I barely want to mention that I own a Precision Power 10F capacitor….it’s not hooked up….it didn’t stop the amp's protect mode when I tried it. But I’m thinking about hooking up the 2 batteries again & adding the cap as well, just to experiment. I’ve read that more "separate" power banks are better for smoothing out voltage. But just $.02, I did sorta think the sound seemed more “present” when I had the cap hooked up.)
2. Get a different alternator. I emailed Michael Singer about my problem (which he seemed familiar with) & he mentioned building me a "6-phase design, voltage regulator w twin rectifiers, high pole count rotor, 2 stators". Could this build make a difference? (assuming the Mechman alt is working as “expected”)? *I don't know much about alternator parts at all. But certainly*before I spend $600 swapping alternators, I'll just buy a different alternator & swap once.
3. Change amplifiers (to analog....mine are both hybrids). I'm wondering if digital/hybrid amps are more sensitive than analog. They sound better than my old Alpine amps (which sounded good) but my analog MRP-F250 never cut out during the spikes. My current amps match my drivers well (still wanting 1 more JBL mkii to run the 4480.1 at .75 ohms). Ultimately I know I shouldn't have to switch them & I'd always worry about popping subs.
4. Tweak PCM software (increase idle speed). Seems like a huge challenge if even possible.
5. Smaller pulley (although as the shop that mentioned the idea said "it's already pretty small"). I doubt this is the answer too.
I'm so tired of turning down my music at every stop light (& I live in a downtown area)...
Any input would be appreciated.
(Sorry for the post length)
