i think i need a new alternator

[Svein]

Just did my summer vacation - 800km on veg oil with no trouble!

I am however worried about my alternator. I think it needs an upgrade. Changed my belt and charged it for three days, but I still saw low voltages(13,9 avg.) and flickering headlights. I could also see the lift pump pulsing more irregularly, when my vegtherm was engaged, so I seems it’s about voltage drops.

I have added quite some load to the system, my vegtherm veg oil heater draws about 25a, and I have 20a of aux lighting, so I think an upgrade is in order to keep the batteries happy.

I’ve been reading all the posts available at the moment and it seems like an ad244 is the right upgrade for my 99 suburban. Which alt would you recommend? Is it enough with 130a, or should I try to go for a 200a option to have headroom?

Cheers

 

[RawbDidIt]

Just did my summer vacation - 800km on veg oil with no trouble!

I am however worried about my alternator. I think it needs an upgrade. Changed my belt and charged it for three days, but I still saw low voltages(13,9 avg.) and flickering headlights. I could also see the lift pump pulsing more irregularly, when my vegtherm was engaged, so I seems it’s about voltage drops.

I have added quite some load to the system, my vegtherm veg oil heater draws about 25a, and I have 20a of aux lighting, so I think an upgrade is in order to keep the batteries happy.

I’ve been reading all the posts available at the moment and it seems like an ad244 is the right upgrade for my 99 suburban. Which alt would you recommend? Is it enough with 130a, or should I try to go for a 200a option to have headroom?

Cheers

I recommend a higher power alternator, but I'd also recommend checking your belt tensioner as well. Voltage drop shouldn't vary unless you're load is varying. May just have belt slip.

For the alternator, I picked up this one from summit. Reasonably priced, and pushes plenty of power for me so far. No lights yet, but I do have 2 amps for a total of about 1500W RMS running off of it with no dimming lights at full power. Link posted below.

The reason I suggest a more powerful alternator is the additional draw you've added. The stock alternator runs at 105A iirc, and you've added 45A of potential draw, meaning you need at least 150A just to have the same headroom you had at stock (which isn't much on these trucks) depending on the lights you have, the initial draw put on the system will likely exceed the continuous draw you see while running, and while the battery can absorb that extra draw, it will cause a voltage drop across all systems. If all you're going to do is already done, then you don't need the 225A that I have, but if you're thinking if adding more lights, a sound system, or anything else, it's sure nice to have the headroom.

https://www.summitracing.com/parts/PWM-48237

Sent from my SM-G965U using Tapatalk

 

[Kran]

for good quality high output alternators for a lower price, i really recommend Custom Electric Service. they have a website but also a facebook page with a shop. their cheapest GM option is a 270 amp unit for $245

but yes also replace your tensioner and belt if you haven't in the past 4 years or so.

 

[Svein]

Thanks for the good tips! When researching the 225A alternator @RawbDidIt mentioned I came across this one: 250A and even cheeper. Any ideas if this is a good buy or a terrible idea?

https://www.amazon.com/dp/B009TD3HF...&pd_rd_r=aef2510b-fe94-4420-9bbc-33ca7e31b7a6

Cheers,
Svein

 

[df2x4]

I'm very skeptical of cheap high amperage alternators like the one in that Amazon link. While the amperage ratings may be accurate when the engine is spinning at 3000RPM, they very rarely put out anything close to their max current rating at lower RPMs or idle. The listing says 125A at idle, but even that I find hard to believe at that price point. More expensive, better quality 250A units from companies like DC Power Inc or Mechman have much better idle current ratings. 180A to be exact, and I would actually believe their ratings. They're in a whole other price bracket, though.

EDIT - Also there are some people in the reviews for that Amazon alternator saying that it behaves much like a stock AD244, and one who says it came with a test sheet stating it doesn't make full power until 3800RPM.

 

[Svein]

Hi @df2x4!

Yeah - I suddenly had a look at the reviews, not too good. I´m contemplating buying a stock ad244 at 145a. I can get it at a reasonable price from rock auto and a crazy price from the Norwegian stores. adding 40a should cover my aux lights and veg oil heater, so it should theoretically be enough.

What to do, what to do. Luckily I am traveling out for work on Tuesday for some weeks, so I have plenty of time to plan it properly and find the right alternator and have it delivered until I come back home!

 

[df2x4]

As long as you don't plan on adding any other accessories that create a large draw I think a stock 145A AD244 should work just fine.

 

[Svein]

Friday it finally happened!
I ended up installing a 230A Tuff Stuff 8237D Alternator from Quadstar tuning. Its an AD244 alternator.

It was a one to one swap for my 1999 6.5. Old one out. New one in. Add a ground connection. Done.
From having varying voltage with my old alternator from 12-13, I am now rock steady at 14,5V even with my veg heater and auxiliary lighting in use. I even seem to read higher fuel pressures in average.

So happy!!

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[Vjcamp]

Do a Ground Voltage drop test from battery to Alternator; one lead on battery Neg other on alternator body, should be .2V or less, if higher check for dirty, loose or missing ground.
Do a positive voltage drop test : output wire of Alternator to Positive battery terminal, again anything more than .2V means high resistance.
do test with engine running