Do I really need a HO alternator?

[Mitch86 5,000+ posts]

You clearly have no idea how an alternator works.

Current Demand and Flow:

If you have an alternator that can produce 120 amps of current (max) and the the total current demand from the electrical accessories (including the battery) is only 20 amps, the alternator will only produce the necessary current (20 amps) to maintain the target voltage (which is determined by the alternator's internal voltage regulator). Remember that the alternator monitors the electrical system's voltage. If the voltage starts to fall below the target voltage (approximately 13.8 volts depending on the alternator's design), the alternator produces more current to keep the voltage up. When the demand for current is low, the full current capacity of the alternator is not used/produced (a 120 amp alternator does not continuously produce 120 amps unless there is a sufficient current draw

I know how an alt works...my point is, that it isn't going to do anything more than its designed to do. Charging additional batteries isn't the problem, its drawing more amps than the alt can provide, correct?

Say you have no load drawing from the alt, what limitations would it have charging multiple batteries?

 

[Flex68 10+ year member]

Think of your alt as a water pump. And your batts some buckets. You stock water pump can pump out say 100 gallions per minute (gpm). Your car probably drinks 50gpm's under normal operating conditions. Now add an amp that drinks 50gpm's. All is well.
Now put in an amp that drinks 100gpm's. Where are you going to get that extra water? From the buckets. Buckets too small and the amp runs out of water, overheats and dies. Add larger buckets and you can use the extra water for longer, BUT the pump has to keep those buckets full too. More water for the pump to pump out means extra strain.

Add a 200gpm pump and you may not even get into the buckets.

****, That's a lame analogy. I could have just said alt, batts and amperage. Lol.

Quite a good analogy, imho.

But I'm waiting on mylows to come back and argue with you about it, like he did with me, lol.

A 2nd battery is, absolutely, just another load for the alt to charge....idgaf what kind of equip you gots, thats just a simple fact from basic AC & DC fundamentals class

 

[BlackHawk99 10+ year member]

So what are we talking here... do I need a pump and a couple of water buckets or none at all? Would a mop come in handy? //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif Seriously though... what do you think?

 

[Slayerx 10+ year member]

I would get a 2nd batt and have big 3 done, and see what your voltage is at, you may get away with it. I am running about a total of 700w rms on a 60a alt. and I dont drop below 13v unless I have my heater on lol

 

[Flex68 10+ year member]

I know how an alt works...my point is, that it isn't going to do anything more than its designed to do. Charging additional batteries isn't the problem, its drawing more amps than the alt can provide, correct?Say you have no load drawing from the alt, what limitations would it have charging multiple batteries?

You clearly have no idea how an alternator works.

................

 

[TaylorFade 10+ year member]

I know how an alt works...my point is, that it isn't going to do anything more than its designed to do. Charging additional batteries isn't the problem, its drawing more amps than the alt can provide, correct?Say you have no load drawing from the alt, what limitations would it have charging multiple batteries?

Did you read what you quoted?

If your alt can't supply the demands alone, you are going to get into your batts. When you get into your batts, your alt has to charge them. Which do you think takes more work... charging one batt or eight? Even if it DID just sit there and pump out max amperage at all times, it's going to take longer to charge eight batts than it will one.

Everything is a load. The car, the amp, the batts. The heavier the load, the faster shit wears out. Period.

Think about it like this... a battery charger. Hook up one battery on say 6A or whatever. It'll charge that batt until it's full. Say that takes 2 hours. Ok, hook up 8 batteries on 6A. The charger doesn't know any better. It could be 1 or 100 batts. It's just pumping out 6A. But this time it takes 8x as long.

I understand what you are saying, but you're thinking about it wrong. You're just assuming that an alt sits there and pumps out max amperage from the time you start the car till you shut it off. That's not how it works.

 

[Mitch86 5,000+ posts]

................

Ok... your buckets are low of water. Your pump only has to provide water for filling the buckets and nothing more.. what keeps it from filling multiple buckets vs. just one? It will still provide only the max amount of water... There...if I use a cool analogy will you get what I'm trhying to say? //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif I know this isn't a realistic scenerio, but I'm just asking.

 

[TaylorFade 10+ year member]

Ok... your buckets are low of water. Your pump only has to provide water for filling the buckets and nothing more.. what keeps it from filling multiple buckets vs. just one? It will still provide only the max amount of water... There...if I use a cool analogy will you get what I'm trhying to say? //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif I know this isn't a realistic scenerio, but I'm just asking.

Ok. Let's try another analogy. Lol

Let's say that YOU had to carry 100 buckets of water or you had to carry 800 buckets of water. Which is going to wear your ass out more. Catch my drift?

 

[Sebaslegrand 10+ year member]

Sorry I'm jacking this thread, don't want to create an entirely new one for something that has been partially answered in here. Just need confirmation.

My OEM Alt. gives out 120 amps. I'm probably going to get the Deka batt, and my system will drain 2000 wrms at peak. This is good, or my alt will not have enough time to recharge my battery and I could end up having a dried up battery at some point?

EDIT : The battery is Deka 105ah dual post model

 

[Mitch86 5,000+ posts]

Ok. Let's try another analogy. Lol
Let's say that YOU had to carry 100 buckets of water or you had to carry 800 buckets of water. Which is going to wear your ass out more. Catch my drift?

but if I were capable of carrying 800 buckets of water, it wouldn't bother me. Lol. But what you're saying is that an alt isn't meant to sustain full output for long periods and will wear it out doing so. I get it. You kind of got my point and I got yours... I'm done. Lol

 

[TaylorFade 10+ year member]

Sorry I'm jacking this thread, don't want to create an entirely new one for something that has been partially answered in here. Just need confirmation.
My OEM Alt. gives out 120 amps. I'm probably going to get the Deka batt, and my system will drain 2000 wrms at peak. This is good, or my alt will not have enough time to recharge my battery and I could end up having a dried up battery at some point?

EDIT : The battery is Deka 105ah dual post model

This is not a hard and fast rule, but I use it as a guideline. As a guideline only.

I use the alt rating and batt Ah multiplied by 10v as an indicator of what I feel may be safe as a minimum.

i.e.- 100A alt + 100Ah batt = 200A x 10v = 2000w.

 

[Sebaslegrand 10+ year member]

So in my situation, I'd get 120A alt + 105 Ah Batt = 225A x 10v = 2250w ? So I'm pretty good? I know it's just a guideline but it seems a fair range.

 

[TaylorFade 10+ year member]

So in my situation, I'd get 120A alt + 105 Ah Batt = 225A x 10v = 2250w ? So I'm pretty good? I know it's just a guideline but it seems a fair range.

I'll tell you the same thing I tell everybody else... Get a voltmeter. And watch it. You see 11 point any-damn-thing, you need more juice.

[Edit: and make sure it's connected to the back batt or to the amp]

 

[TheUnderFighter 10+ year member]

@ OP... I think you'll be fine, with a minimum of a Big 3 upgrade. You may need more, you won't know until you plug it in. I would think an HO alt to be rather excessive though. I like TaylorFade's guideline though. And that volt meter is a great suggestion, you definitely need to keep an eye to where your voltage drops.

 

[bobtherider123 10+ year member]

i might be able to help you, i have a 91 toyota mr2 that i swapped the v6 from a 93 camry into, i have been using a 1200w ab amp that is about 9 years old now for the entire time i owned this car. at first i was blowing voltage regulators almost every 3 weeks on the dot. then i purchased a stinger 1 farad capacitor and it stopped popping alternators. i have been running on the same battery, cap, and alt now for about 2 years and almost never have my radio turned down and bass is always as loud as my old amp can handle. if it helps any i can even take pictures off my setup and how i wired it.

setup specs:

sony xm-2200gtx amp

Sony XS-L121P5 350 rms sub 1200w peak

pioneer AVH-P2300DVD

6 1/2 kicker 3 ways in the door and 4 inch kicker 3 ways in the rear and 1 1/2 infinity tweeters in the door.