Alternator Capability versus Loads

[Maxs Dad]

Has anyone found out how much juice these trucks can generate versus how much load the stock setup puts on the electrical system? There are goodies that I want to add but I don't want to find out the hard way (dead batteries) that I've added more goodies than the stock system can support plus maintain a charge on the batteries.

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Jim E. - Newbie to Diesels w/2001-2500Quad-4X4-LB-Bronze Beauty

 

[Big MAK]

In general, we're really safe with the dual battery setup -- so long as every gizmo you got isn't on when you're trying to crank it over on a cold day. Unfortunately I don't have any numbers for you. Watch the charging amps gauge and if it's staying at or above 14 amps under your usage then you're still safe. If it starts dropping under then you need a bigger alternator.

Let's just say I run dual backup lights, utility warning light, all headlights and running lights, after market stereo, CB, hydraulic pump that draws like the niagra waterfall sucks water, phone, ... and the only time I have to watch the current draw is immediately after I crank it over on a cold day. Once the grid heater doesn't have to cycle on and off I can run everything with no impact.

If I start the truck on a cold day and immediately hit the plow lift switch, while the grid heater is still on, warning light blinks on and the amps show 8. Doesn't stall or anything just let's me know it doesn't appreciate it.


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Big MAK
98. 5 ISB 5spd 4x4 Quad Cab 3500, 275s and Original PowerMax
A "WARRANTY FREE" ZONE
https://www.turbodieseltrucks.com

 

[K_Arts]

I'm with you Maxs Dad. I would like raw numbers on this. Here I know that I have a 136 amp alternator. But as I am upgrading my sound system... a lot of amplifers have 80+ amp fuses on them. The amplifier that I was looking at has dual 100 amp fuses. I haven't gotten it yet due to me not knowing what type of load I currently have, and I can tell you that having an amp with a 100 amp load, you have to have an isolator on the Alternator between a dual battery setup. Being that we don't have an isolator between our batteries... I have no clue what they can handle before the lights start dimming. . engine starts struggling... etc. LOL

Any one with numbers... please let us know????

Thanks

Kev

 

[BV]

Sorry Big Mak but the guage reads in Volts not amps. Just wanted to clarify in case others got confussed.

 

[Big MAK]

Ah yes, thanks BV. Must wake up...

 

[Maxs Dad]

K_Arts - Are you replacing the intake air heater with those Amps? - The reason for the big fuses on those Amps is to handle the instantaneous - very short - spike of mega-amps needed when a bass note hits the speakers. The average drain is probably 25% or less of the rated capacity of the Amp. Still - I want to keep more electrons on tap than I'm using.

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Jim E. - Newbie to Diesels w/2001-2500Quad-4X4-LB-Bronze Beauty

 

[pcorssmit]

Kevin, try putting your muffler back on. Then you won't need such a big amp. #ad


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'97 2500 CC 4X4 5spd Sport
'83 K5 Blazer 350 TBI (ex 6. 2), 39. 5 TSLs, 3" lift, Dana 60/GM 14 blt, Detroits

 

[Pete Peterson]

You have two 750 amp batteries for a total of 1500 amps @ 12volts. The altenator will recover the batteries in seconds or less. The batteries are doing the work the altenator recovers them. This altenator will put out 148 amps when drawn down to battery voltage. Hope this helps. Pete

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01. 5 Loooaded up!!!!!

 

[Maxs Dad]

Pete: Are you sure that these aren't 750 Amp/Hour batteries? Not just 750 Amp batteries. You are right we do draw off the batteries and restore with the alternator but it's a common bus system meaning that I can pull from both batteries and alternator simultaneously - Typically - once I've topped off the batteries the majority of my current is supplied by the alternator. This hard lesson came from trouble shooting the charging system on my boat - which has a flat-head - circa 1945 gas engine #ad


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Jim E. - Newbie to Diesels w/2001-2500Quad-4X4-LB-Bronze Beauty

 

[Pete Peterson]

Jim, frommy learning which could very well be flawed, the current draw will always be from the battery but the recovery time is so fast that you would think its coming from the altenator. With the battery charged up the altenator is pushing across the battery but still it is coming from tha altenator by way of the battery. The reason I say the altenator recovers the battery is due to event in which your load demand is less than the altenator capacity you maintain voltage, when you exceed that capacity you still get the current but with a reduced voltage capability. Disconnnect the battery once its started and the altenator is doing the work but if you don't increase rpm a large load at idle will kill the engine,(not enough current to run a load at idle.
Yes its ampere hour rating @750 amps. I believe its 750 ca or on some cca which is either cranking amps or cold cranking amps.
Now that I've said all this I realize I'm probably way over my head on this subject. Regards Pete

 

[HC]

Are you sure that these aren't 750 Amp/Hour batteries? Not just 750 Amp batteries...

I don't know the exact rating of the Dodge batteries, but 120 amp-hours would be a larger than average deep cycle marine battery. I'm pretty sure there's no way the batteries could be much more than 120 amp-hours, X 2 of course. 750 must be the cca

 

[Maxs Dad]

OK - Now lets carry this conversation further. Why will the engine die if you disconnect the battery but leave the alternator connected to the main engine power buss? Presume that none of the lights, blower motor, heater grids etc. are on - just the electronics needed to control the injector pump and the fuel pumps - and what ever else is needed to "just" run the engine. The Alternator should be able to adjust it's output (using the regulator) to match the current consumption of the engine electronics.

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Jim E. - Newbie to Diesels w/2001-2500Quad-4X4-LB-Bronze Beauty

 

[Pete Peterson]

Your right Jim it will run just fine. I was just saying with added load at idle it will die, like turning on the AC and the lights, at idle the altenator won't keep up and it dies. Pete

 

[Bad340fish]

Out batterys our 750CCA which is 375 amps. So total aperage the batterys can put out is 750 between the two of them. As far as amp hours go i forgot the formula for that.

I wouldn't suggest trying to unhook the batterys at idle. It causes strange stuff to go on. I did that with my barracuda(but i had the lights on) when i hooked it back up it blew out every bulb that was turned on at the time. All the wasn't burnt was the high beam, brake and turn signal lights.



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Clark
1999 2500 QC SB 5spd all stock for now
1968 Barracuda Formula S Viper Blue 11. 98@112

 

[Maxs Dad]

What happened Bad340fish is that the batteries provide a load for the alternator. Removing the battery load allowed the alternator to put out high volts until the regulator could bring it back under control. Kinda like pulling up a hill in 4th towing a 5K load then all of a sudden dropping the load. The other thing that can happen is to blow the rectifier diodes in the alternator -
not a good thing - means new pricey alternator. Another question all - There are aftermarket alternators available up in the 175 amp range. Anyone installed one of these to drive the 'fridge for the "Cool Ones"?

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Jim E. - Newbie to Diesels w/2001-2500Quad-4X4-LB-Bronze Beauty

 

[drawson]

These alternators are surge type alternators they aren't designed to run at max out put for very long. The wiring used inside is alot smaller than the older hi out put alternators.

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EAT'M UP
97 2500 Club 4X4 3. 54, Forrest Green/Driftwood, LSD 5 speed, & Psychotty Air System, TST #11, 370 HP injectors, timing at 16 deg. , 16CM2 housing, AFC spring kit, Geno's Exhaust Blanket, TST EGT gauge & 0-60 boost gauge in A Pillar, Cat-be-gone, 4" Dynomax Bullet muffler, Crome 4" turn down, Rad fan removed, AmsOil Through out, Geno's trans filter kit, AmsOil Bypass system, Lund Winter front, Leer Cab Level Shell Driftwood , 255/85R16, Dyno'd 342 HP pre injectors & turbo housing *NRA/USPSA member and proud of it*

 

[illflem]

Seems I recall one of the options available when I bought my trucks was a larger alternator for higher power needs like wenches etc. The stock alternators aren't all that fast,a grid heat cycle (180 amps)will take about 1/2 hour at higher rpms to recharge the batteries.

Well the 12 valve wins again,once it's running if you wire the fuel shut off solenoid open no power is needed,for the engine at least.

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95' 25004X4,AT,Driftwood,Banks Stinger,Warn fender flairs and running boards(work truck)
95 3500,5 speed 3:54,Driftwood,Banks&Psycotty,34,000 GCVW apple and tractor hauler(works harder truck)

 

[K_Arts]

OK guys... gotta tease me about the amplifier I am looking at. . though Jim you are probably right. I betcha I can use this amplifier as a replacement for the intake air heater... ha ha ha.

Pete, NOOOOO If I put my muffler back on. . I will just have to put in a bigger amp, to make up for the noise that I lost. . LOL

Actually it is an 8 channel amplifier that is capable of running multiple channels down to 1 ohm. There are 6 channels for satellites and 2 channels for subs. So there is a 100 amp fuse for the Satellites and a 100 amp fuse for the Subs. Just to clearify... NOOO I am not making my truck of those that just pours out bass. I just love my music clear and loud. I get this from the old days when I used to compete in sound contests. LOL

Kev

 

[RoryTek]

Ok guys, this is the place for all your answers, call them!! http://www.chuysautoelectric.com/

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Rory KE6NIG
97' 3500 CC 4x2
12V,TSTed, Auto, Bright
White/Spruce Int. Amsoil, Muffler fell off 20k ago, I think the CATS next.

 

[rickhans]

Maybe I can answer these questions. Over the last 5 years, 3 of our vehicles (I had 4 kids in school and maintained all of their cars along with my 3 4wd vehicles) fried the main computer. I have taken each one of them to a shop that specializes in electronic and computer problems. Being a computer systems engineer, the owner of the shop explained it to me in "computer-ease".

The battery acts as a giant capacitor and surge protector, much like plugging your computer at home into a battery back up surge protecting system.

In at least two of the cars, I had defective batteries. Normal battery tests do not detect the problem that was going on, but the way I understand it, the battery failed to go to a full charge, thus requiring the alternator to continuously put out max amps. Somewhere in the process of discharging and not fully recharging, it failed to suppress a voltage spike from the alternator and fried the computer. On the 3rd car, she had some one jump the battery when it went dead and a surge resulted and destroyed the computer.

If you ever disconnect the battery with the engine running, you will get voltage from the alternator but stand a high risk of blowing the computer. I think it is something like having a floating ground. For this reason, I was told to always disconnect the positive cable first, then the ground, with the engine off.

Wish I could be more specific, but I don't fully understand the electrical side of all of this.