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Discussion Starter · #1 ·
It's a shame when a pickup truck has to deal with recreational vehicle cycling batteries and the ECU could care less. But the ECU does not permit direct substitution. Something needs to go into the A field circuit feed to the ECU to satisfy it enough not to go into open-loop limp-home mode. Has anyone done any research on this and pray tell, developed a work-around to allow a "smarter" voltage regulator to be employed? -Thanks!
 

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Sorry, it's not clear to me what's happening, and what you want to happen. Can you explain it a different way?
 

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Bob Lincoln said:
Sorry, it's not clear to me what's happening, and what you want to happen. Can you explain it a different way?
Im with BOB, Is it under charging, Over charging. Charging but cycling too much? or just the battery light on the dash?
Then we can try and help you out.
 

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1966 Crown Coupe, 2016 200 S AWD, 1962 Lark Daytona V8.
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Is this a diesel Ram with the dual-batteries? Are you using deep-cycle gel batteries? There is not enough information here as stated.
I can't see a charging issue putting the PCM EFI system into limp-in default and if it did, what are your fault codes? I think that you may have another electrical problem with the truck.
Are you trying to charge external batteries as you drive? Are you using an aftermarket battery isolator?
The charging voltage regulator can't be fooled by inserting a static 13.7 volts, as it has to see 'field voltage action/battery voltage reaction' in order to confirm the charging system tests.
 

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Discussion Starter · #5 ·
With RV batteries, they are meant to be discharged to around 50% of capacity then recharged. But the truck ECU charges at 14 volts only for a little while, a very little while, then backs off to 13.5 volts. It takes roughly eleven hours of driving to recharge a couple of RV batteries at that rate of charge. When going from one bookdocking site to another this is impossible. It really gets nuts when the campsites do not allow use of a generator. Solar planels don't work too hot in the shade, and parking in the sun many times means a rig temperature of a hundred ten degrees.

Is there public access data that furnishes parameters that the ECU demands to see without generating a fault code and going into limp-home mode? The data would include alternator field current in relationship to battery voltage, voltage failing to or too slow rising, too high, etc. Putting on a second alternator seems to be out of the question. No room, and modifying pulleys and building a custom bracket would cost thousands of dollars.
 

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I think what you want first is charging specifications (amperage rate and voltage) for the RV batteries. Then look into how to buy or rig a charging system for them. Without knowing, it may be appropriate to charge them more slowly than you think. Fast charging is always harder on batteries than a slower rate.

Can you rig solar cell blankets on top of the RV, and have them charge the batteries while you drive? I've seen a blanket size panel put out 21 volts and many amps, so that a regulator is needed to keep the batteries from boiling. That way the batteries can be charged by the time you reach your destination.
 
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there are after market voltage regulates that by pass the ecu and install a adjustable voltage regulator to the alt the kit run about $80.
 

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Welcome to Allpar. Yes, but then you will have a 'ck eng' light on with a charging system fault code stored. On newer vehicles, the PCM internal voltage regulator must be in charge of charging. It looks for a charging voltage reaction as part of its self-test. If it tries to change charging voltage, but doesn't se its expected result, it will set a fault and turn on a warning (ck eng or battery) light.
P.S. - This is an 8 year-old thread.
 
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You wont gain much even if the ecu went for 14.4v it´ll still be slow charging to avoid gassing.
What you could do is to install a 12- 110/ 240 converter and then run a batterycharger of it, that would charge your batteries in a much better way and faster.
 

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With RV batteries, they are meant to be discharged to around 50% of capacity then recharged. But the truck ECU charges at 14 volts only for a little while, a very little while, then backs off to 13.5 volts. It takes roughly eleven hours of driving to recharge a couple of RV batteries at that rate of charge. When going from one bookdocking site to another this is impossible. It really gets nuts when the campsites do not allow use of a generator. Solar planels don't work too hot in the shade, and parking in the sun many times means a rig temperature of a hundred ten degrees.

Is there public access data that furnishes parameters that the ECU demands to see without generating a fault code and going into limp-home mode? The data would include alternator field current in relationship to battery voltage, voltage failing to or too slow rising, too high, etc. Putting on a second alternator seems to be out of the question. No room, and modifying pulleys and building a custom bracket would cost thousands of dollars.
 

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A battery, whether depleted to 50% State of charge, or only to 90% state of charge, will accept 2 to 3 times as much amperage, at 14.7v vs when it is held at only 13.7v. It is 3 times as much when the battery is new and healthy and closer to 2 times when it is midlife or older.

A depleted battery held at 13.7v is infuriating, as it could be recharged to 80% state of charge 3 times faster if the dang voltage regulator would just hold 14.7 vs 13.7v.

The battery itself determines the amperage accepted at the electrical pressure delivered to its terminals. This number is influenced by battery size and health and original resistance as well as temperature and how long its been since its last true full charge, which is closely related to battery health.



These numbers are not made up. I have Ammeters and voltmeters on ALL my multiple adjustable voltage charging sources, and now, because of the Op of this thread, I have dials on my Dashboard controlling my external voltage regulator which controls the alternator, and soon to be plural, alternators.

Back in 2013 or so, I was pestering David Eidell about how to trick the in ECM voltage regulator, as he was the most knowledgeable person on lead acid batteries and alternators I knew of, and still is. We just both had no idea what the voltage regulator inside the engine computer was thinking or expected or required in order to be tricked and not set off the check engine light, and causing some sort of 'limp home' mode. This ultimately was not answered.

On my 1989 B250, tricking the ECM into thinking it is still hooked to the alternator, when it is not, is accomplished with a 10 Ohm 50 watt resistor placed inbetween the two ring terminals which previously were attached to field terminals on the back of the externally regulated alternator. One can then use an external voltage regulator, and the Check engine light will not come on.

I paid way too much for this 'field replacement module' from this outfit:


in order to figure out it is 10 ohms, and then finding equally spec'd resistors for a fraction of that.

The CEL, will not come on ,Unless the engine computer is expecting to see its own peasly inevitable choice of 13.7v, and the external regulator is holding over 14.7v, for more than 30 seconds.

If it does, then the check engine light comes on and the engine runs a bit crustier as it seems to revert to not reading any of the sensor's inputs. The CElight will go out on the next engine start up, but the crustyness continues until the ECM is reset. It is not an issue in my experience, I just keep it at 14.7v or less and the CEL never comes on.

And while true it is usually less abusive to charge a battery slower, it is not always true.

When the battery is destined to be cycled that night, it is far less abusive to charge it quickly and get it to as high a state of charge as possible, than it is to slow charge it and thus deplete it even further than night and overall allow it to remain at low states of charge and allow the sulfate to harden on the plates, obscuring the surface area for the chemical reaction to occur..

Also, Most AGMS will be ticked to death with light charging currents in deep cycle Duty. COncorde, who make the most respected deep cycle AGM batteries on the market, Lifeline, specifically say the higher charging amperage the better.

scroll to page 20:

There are reports all over the net by Rv-ers, who never bothered to meet Concorde's minimum 20 amps per 100Ah of capacity in deep cycle use that the lifeline tech manual linked clearly specs, who have destroyed the capacity of their expensive battery banks prematurely, by thinking low and slow charging is always best.

I employ Northstar AGM batteries. TPPL AGms, thin plate pure Lead. Very similar to and now the same parent company as Odyssey AGM, a more well known name.

Odyssey AGM says NO LESS than 40 amps per 100Ah of capacity in deep cycle duty.

Page 16



Les$ser AGMS do usually say to limit charging amps to no more than 30 per 100Ah of capacity. I've grossly exceeded this rate on many that say exactly that, without issue , or excessive heating, or gassing.

The whole 'trickle charge it overnight' mentality is the bane of a well discharged long time undercharged battery, and especially AGM batteries.
I wish this old wives tale would not be repeated so mercilessly by those who have zero experience actually testing batteries and observing accurate tools and collecting data in different uses and recharging regimes.

If one had 8+ hours to fully recharge a deeply cycled lead acid battery, then by all means tailor the initial amperage allowed to allow it to reach 100% by the time the battery needs to work again.
But, those AGM batteries that specifically say no less than 20 or 40 amps per 100Ah of capacity, like Lifeline or Odyssey, will have their performance and lifespans kneecapped by the low and slow recharge mentality.

Quality deep cycle flooded/wet/ sloshy batteries like Trojan usually recommend a 10 to 13% rate, but this also assumes one has a significant period of time to recharge the floor scrubber battery or golf cart, before its next use. This recommendation is likely what might yield the least warranty returns if they have guessed exactly how their batteries are going to be treated by a majority of their clients. Their reccommedations are driven as much as by maximum potential profit, as is actually what is best for them and they have adjusted their recommended values more than once in the last 15 years.

in RV usage, deep cycling the battery each night, it is far more important to get the battery to as high a state of charge as possible before the next discharge cycle begins, as partial state of charge cycling is extremely detrimental to the capacity of lead acid batteries.

PSOC cycling means starting the next discharge before a true 100% recharge has occurred, and the lower the % achieved before the next discharge begins, the more detrimental to the battery it becomes. Also when one does indeed have the time and means to then truly fully charge the punch drunk PSOC'd battery, it takes significantly longer to actually attain a 100% true full charge. Not just an hour or two either, think 6 or 8 hours longer being held at 14.4v+ before specific gravity maxes out or stops rising. Allowing only 13.7v on a punch drunk battery, will NEVER truly fully recharge it, no matter how long it is held a 13.7v.

Most smart chargers do a horrible job of topping off a punch drunk battery. One will need to remove the surface charge and restart the charger over and over and over again until they take the charger, swing it by its power cord against the sharpest most immovable object they can find. This of course assumes one is either using a hydrometer on a flooded battery to determine when maximum specific gravity is attained, or on an AGM full charge is determined by the amperage the battery accepts when held at absorption voltages, 14.4+ volts, temperature dependent of course.

And yes Ignorance is bliss, at least until the battery 'no longer holds a charge' at the most inconvenient and expensive possible time to do so.

Also, if one is using a generator to recharge in daily deep cycle duty, it behooves one to achieve 80% state of charge as rapidly as possible. Above ~80% the battery starts limiting what it can accept at any charging voltage so running a generator at higher states of charge, just to achieve the ideal 100%, becomes more and more wasteful of fuel and silence.

I have been successfully tricking the ECM, and running a separate voltage regulator, since January of 2017. I've got several calibrated voltmeters, ammeters, and amp hour counters to keep watch over my deep cycling batteries and can now, finally, achieve excellent lifespans of my lead acid batteries. I can charge them as fast as possible every time my engine is running, and not at 1/3 the possible maximum like when the ECm's voltage regulator decided
13.7 was fine and dandy, which is why this thread was started.

A recharging regimen/ voltage regulation which might be 'just fine' for an engine starting battery, keeping it at relatively high states of charge, and allow it to live 4 years in such a duty, will quickly kill a deeply cycling lead acid battery.

The amount of poor information on the web about the proper care and feeding of lead acid batteries, especially those cycled deeper, intentionally or not, that is spouted by skilled experienced otherwise intelligent mechanics, is rather astounding.

The voltages my ECM would allow, which was 14.9v briefly after start up, then 13.7 90% the rest of the time with occassional spikes to 14.1 or 14.7 had me replacing batteries in less than 2 years and under 250 deep cycles, but arguably would indeed be just fine if the battery were only ever used for stating the engine, which is about 0.25 seconds of a 180 amp load to get it turning, and then about 150 amps until the engine catches. The actual Starter amperage varies with the voltage the battery is able to maintain. But a 1.4KW output starter is going to need very close to a peak of 1800 watts from the battery.

Now knowing just how much time and amperage it takes to keep deeply cycling batteries happy, My last battery lasted ~1200 deep cycles, many of those drawing it well below 50% state of charge, and 6 years. Just before i replaced it, its voltage, when fully charged, was falling to 7.8 during engine cranking.

One other thing I wish would stop being repeated, about lead acid batteries, without qualifying statements, is that short trip driving is alone, a battery killer.

While true that a short trip regimen will never be able to return a well discharged battery to high states of charge, the actual amount used by the starter to start the engine is returned within a minute of starting the modern fuel injected easily starting engine, when the voltage regulator, seeks mid to high 14's after starting the engine, which most do.

Unless short trip driving consists of less than one minute of engine run time,hundreds of time in a row with never a longer drive between, then short trips are not the battery killer they are widely and mercilessly reported as being, over and over, as if sheer repetition makes it so.


Anyway I don't know if a 10 Ohm 50 watt resistor is the magic number for installing between the original wires which attach to field terminals of ALL Dodges with VR's internal to the engine computer, but it is for my '89 B250. In retrospect I would have gotten a resistor capable of dissipating 100 watts of heat, but I used arctic silver thermal epoxy to attach a larger finned heatsink to it. I've added more heatsinking and ventilation to many things.

I've also disconnected my external VR and reattached the wires to the ECM's VR, and it still works like it always did, choosing 14.9v after starting, dropping to 13.7 within 10 minutes and thereafter only briefly spiking to 14.1 or 14.7 or 14.9v.

I never figured out any correlation of when or why the ECM's internal VR decided to revert to 13.7v from 14.9v, as the time after startup in which it did, was always a bit different, and when it spiked to 14.1, 7 or 9v briefly after that, I never noticed any reason as to why. It seemed completely random.

Random and infuriating.

And now, having successfully tricked and bypassed the ECM's VR, can finally treat my hard working deep cycling batteries much closer to ideal.
Actual Ideal, not internet folklore ideal.

I don't use a Mopar voltage regulator, but David walked me through hooking ujp a Transpo 540HD, which is designed for a ford. There are adjustable voltage mopar VR's available now if one prefers.

On the transpo 540 HD there are 4 terminals. The casing of the alternator must be well grounded to battery -.
The terminals are lettered I A S F
I is for idiot light, I ignore this terminal
A is for Always on, Hook to the battery +
S is for switched 12v. I found a quick connector under my dash which becomes live only after engine starting
F is for field. run this wire to either of the two field terminals on the externally regulated alternator. the other terminal must be grounded.

Inside the casing of the transpo 540 there is the blue voltage adjustment potentiometer. with 3 legs. It is potted, but in what appears to be liquid electrical tape. It is a 2K ohm potentiometer. The pot can be lifted and the legs cut with some nice side cut nippers

2 of the legs have continuity and I solder one black 22 awg wire to both of these, and one red 22 awg wire to the other pot leg. These wires goto a Bourns 2k OHM 10 turn potentiometer located on my Dashboard.

Anyway, I absolutely love having this level of voltage control, and so do my batteries. Using AGM's one determines when they have reached full charge by amperage accepted at absorption voltage.

When amperage into my 100 amp hour battery tapers to 0.5 or less, I lower voltage to 13.6, but if cold or at night, with the lights on, 13.6 seems to allow the battery to very slightly and slowly discharge, so I bump it to 13.8v.

If the battery is full and it is midday I will lower voltage to below 13.6v, that way my solar panels, whose voltage regulator( charge controller) set for 13.6v float will take upto 200 watts of load from the alternator to run the engines ignition and fuel pump, which is about 8.2 amps at idle and 12.2 amps at 2K rpm.

If the battery is not full and he sun is out I will set my VR to just under 14.7 so the solar panels contribute all they can, taking upto 200 watts of load off the alternator.
S terminal( which carries very little current from teh switched ignition source, and each time a single alternator cannot meet the amperage demands to achieve or maintain my desired voltage, the other will be turned on.

One is a chrysler 50/120 alternator, one is a 50/120 Nippondenso clone alternator. The chrysler alternator can meets its rating hot, the made in Malaysia Clone alternator, cannot, but will output slightly more than the chrysler from ~ 850 to 1600 rpm or so.

The ND alternator is where my AC compressor used to reside. I've yet to wire it up, but it is nearly perfectly aligned. It might run cooler up here and perform better when hot, since its backside will not be right next to exhaust manifold. The data on its disappointing hot performance, were from when it was located next to manifold.

The space between the dual V belts of the ND alternator, do not match the crank pulley, or the Chrysler alternator or the AC compressor it replaced. I intend to remedy this and run matched belts, if I can acquire them.

But the original alternator was 6mm out of parallel alignment with the crank pulley indicating that V belts are pretty dang tolerant of misalignment, and how many ND alternators out there on similar era dodges are fine with the difference in belt separation?

But ideal means perfect pulley alignment of both matched V belts, so that's where I'll aim.
 

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Its correct but 14.7v wont "fast" charge your batteries and it´ll boil your starter battery.
-problem is that you ask for 2 purposes from one single alternator and that were the charger comes into place.
 

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Putting on a second alternator seems to be out of the question. No room, and modifying pulleys and building a custom bracket would cost thousands of dollars.
In what vehicle? Dodge Dual Alternator Kit with 280XP High Amp Alternator for 6.7L Diesel Engines

 

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I'm in same situation, running 320 ces alt, bracket, 250 ho stock hairpins. 48ah lithium, 13.5 resting, 14.8 max charge lifepo4's,
Stinger 200 amp is,
Agm? Starter bat group 34.?
Thing is with just the 320 and lithium it was great and now it's been a nightmare. Symptoms keep changing. Crank no start. Harness swapped cleaned. All but for fuseable links...
Field replacement modual 10ohm. Series? Parallel? External reg field to where? 59 pin? PDC DB? Run. Or gage cluster, incandescent only? Field.
12.8 LA deep cycle
Iso
14.8 Headway lithium
Symmetrical grounds.
To encompass (22awg fuel pump to cluster to drivers fr fender first. Circuit A1.
Low points both drivers side to ground View attachment 80375 View attachment 80376
 

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Since June 2015 I've been getting away with a single Northstar AGM for house loads and engine starting. Never an issue.

BUt with a house and starter battery, overcharging the engine battery is a possibility certainly, On long drives when that drive was started with teh battery already at very high states of charge.

basically lead acid batteries require 3.5 hours to get from 80% charged to 100% with very few exceptions, that 3.5 hours asumes 14.4v+ is held then entire time. 80 to 100% at 13.6 v on a new healthy battery will take 12+ hours and on a mid life or older battery will never truly fully charge it.


I do not have experience with Lithium batteries, yet. I got Lead acid dialed in and several years before they are due for replacement.

However when I think about it, with two alternators, I would have the engine starting battery and the lithium battery bank on their own alternator.

I dont know what it takes to trick and manipulate bypass the VR inside the ECM/PCM of newer Dodges, but if I had a newer vehicle with one alternator, I would use a DC to DC charger like from Renogy or Sterling, that is capable of delivering to the Lifepo4 battery exactly what it wants, working with its BMS, within its limits.

If the vehicle had a second alternator added, i would not touch the OEm wiring to the original alternator, just let it do its thing, and have the second alternator, have it completely separately regulated and feeding the Lifepo4 battery the voltage it wants.

A danger with this is the BMS, when it cuts off charging current to protect the Lithium battery, it could take out the diodes in the alternator if the VR or its field wire is not disconnected at the same time as well.
 

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Since June 2015 I've been getting away with a single Northstar AGM for house loads and engine starting. Never an issue.

BUt with a house and starter battery, overcharging the engine battery is a possibility certainly, On long drives when that drive was started with teh battery already at very high states of charge.

basically lead acid batteries require 3.5 hours to get from 80% charged to 100% with very few exceptions, that 3.5 hours asumes 14.4v+ is held then entire time. 80 to 100% at 13.6 v on a new healthy battery will take 12+ hours and on a mid life or older battery will never truly fully charge it.


I do not have experience with Lithium batteries, yet. I got Lead acid dialed in and several years before they are due for replacement.

However when I think about it, with two alternators, I would have the engine starting battery and the lithium battery bank on their own alternator.

I dont know what it takes to trick and manipulate bypass the VR inside the ECM/PCM of newer Dodges, but if I had a newer vehicle with one alternator, I would use a DC to DC charger like from Renogy or Sterling, that is capable of delivering to the Lifepo4 battery exactly what it wants, working with its BMS, within its limits.

If the vehicle had a second alternator added, i would not touch the OEm wiring to the original alternator, just let it do its thing, and have the second alternator, have it completely separately regulated and feeding the Lifepo4 battery the voltage it wants.

A danger with this is the BMS, when it cuts off charging current to protect the Lithium battery, it could take out the diodes in the alternator if the VR or its field wire is not disconnected at the same time as well.
Excellent thus concured. In the beginning I had Ces 320 alt, ex regulated 2 wire output, tapped into 7mm bolts of old stock alt/field wires DB 5 ohm & GR 10ohm fields. Problem is averaged 13.9 saturation. (14.8 max)13.55 resting.
THEN CRANK NO START..BEGINS, BATTLE UNSUES.
Stress cased studies, learnt up some on mid year changes in 92. Evident from fuel pump ground allllll way up front fender. Mind bender to cluster fucked for full field burnt bulbs. ?s arose con vs pro Led's or incandescent ammeter field? Dash k1 point now at midlifemeltdown, reset pos neg 30min Nice, refurbished computished enough to rough idle, tps, and field not switching proper. Order dead out the box 250 ho stock, alt to no avail sale item, I might've just power probed 59 pin in the wrong [I have a dirty mouth] was I then to do...50w10ohm..briefly remember 62.5ohm @GR to gr @ecu * parallel near alt.
320 2 wire (via fatboy ex/reg instructions 1 wire case ground 2nd to field? I tapped Run at column(start of field circuit to F on ex/reg. (F), (h) to Lifepo4 +,(g to alt case....no? Ok lifepo4-. Fatboy just loud fan spun volt meter as (g) loose and (h)was at in on column and column (f). Full fielded, jumped 18v. May have grounded 1st to coil bracket ...in English, trying to integrate alt directions one field one ground. Didn't mesh with power ground switched ecm. Fatboy never adjusted just impeded 5ohm .5v drop from bat+ to b+ alt? Wtf? No excitement now.?
Brains mush.
Stock out with your new alts out return to sender more money spender with cranked Mopar sensor(piece of tape drop bell housed grom. Hall effect replaced and correct. 5v referred 4.7 variables pulls .7 @1500 IAC sprayed carb cleaned. Some harm seen butterfly oils indicate valley restricted going get er doubled plate gasket re seal and smash it as soon as second in engine stand get stimulus package? When's that to happen.? Not now then..so.
Bench test alts hope I didn't fry poking power probed with my backwards logic sidekick, got me so confused I forgot how's I do, and I'm the one who wired it. So for the 20th time I refired him. And his Bullet bourbon.
Eeprom, scratched gel coat and extract caps. 2,200uf 25v. Ebay suggests I may not have to go far to Mopar. Agh fuckin figured it out?
CAUSE YOUR GOING TO KEEP BUYIN MOPARTS.
Failed on race day they say, beats crank no starting your money away. LFSM replace both components it says. But now somehow, it runs of just Batery for a few days..and Dies again. Scratched heads of 4 mechanic friends. All say go back stock naysayers talk.
But I cantI've come too far so what's known 62ohm static charge? Volt drop from fatbox, welding cable addition to ground spots. Don't lose k1 fuel pump front fender no start box torn part return to sender, endeavor never ends. Lead acid deep cycle just might though blew bubbles and pissed. Genius charger fix this,?,? Or no! Gots to go. Bringing down voltage even isolated so. Dedicated 320, buy new much cheaper next reg. Cause the fatfailedtofield bunked deal and fried incandescent suggest it's in the next chapter to come? Holy fuckin poopies already singleboards are deadly. Killing me slow. View attachment 80401
 
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