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Frustrated..wat would you guys do?

 

Silver Member
Username: Wackzirth88

K-town, Il U.S.

Post Number: 387
Registered: May-09
ok so i figured id give em a try and ordered a h/o alt from db electrical. suppose to be 200a at 1200 rpm n 105a at idle, but wats idle to them? im running a sundown sae 1200 v2 at 1 ohm so around 1500w rms. when im driving down the road the most ive seen voltage drop is about .5 volts on very low hard hitting songs. that part is wat i do like. wat i dont like is when i pull up to a stoplight or stop sign voltage sits at 13.1 with nothing on, 12.6-9 with my lights on. if im in park at idle voltage will sit around 13.9 but if i do anything, roll down a window, turn on the air or heat it drops dramatically, windows pull it down to low 13s(thats one window at a time, rolling down multiple windows at idle kills it brings it to like mid 12s. n air or heat put me at about 12.7. but jus the weight of my foot on the gas puts it at 14

is there anything i can do to better it at idle? the alternator shop here said i cant go any smaller on the pulley because there wont be enough surface area for the belt. i really like how the voltage is when im driving but im concerned that im going to kill my batteries(stock duralast upfront and kinetik hc1400 in the trunk). i just keep thinking of senarios that make it seem like i should just get my money back, run stock alt, and just set turn my amp down. i was thinking wat is goin to happen on a really hot or cold day. i dont think ill be able to run my a/c or heat at idle without draining my batteries which really sucks cause it gets f'n cold here in the winter and now its gettin f'n hot. wat would you guys do? got til next tuesday to send it back for full refund
 

Platinum Member
Username: Glasswolf

Post Number: 13625
Registered: Dec-03
idle is typically around 600-800rpm.

"wat i dont like is when i pull up to a stoplight or stop sign voltage sits at 13.1 with nothing on, 12.6-9 with my lights on. if im in park at idle voltage will sit around 13.9 but if i do anything, roll down a window, turn on the air or heat it drops dramatically, windows pull it down to low 13s"

this is normal, and exactly how it should be.
As long as you're above 12VDC, you're golden. don't sweat it.

If you really want to steady those momentary fluctuations, add about 3 to 5Fd of capacitors (low ESR ones) to the setup. That should do the trick to stabilize everything.
 

Silver Member
Username: Wackzirth88

K-town, Il U.S.

Post Number: 388
Registered: May-09
wat about the a/c and heat question? when my cars a idle in park with the heat or air on it pulls voltage to like 12.7. say i leave my car running for 20 minutes with the heat on in the winter i wont have to worry about killin my batteries?

i just expected to see constant 14s i guess. ik your running a h/o alt, do u see flucuations like this?
 

Silver Member
Username: Wackzirth88

K-town, Il U.S.

Post Number: 390
Registered: May-09
idk, its just i expecting it to be overall better then stock alternator. my stock 110a alt only went done to 13.6 at idle with the air/heat on high.and voltage didnt drop at stops. but on the other hand the voltage wasnt close to the same as it is now with my system on and driving.

if i do decide to go back to stock alt, would it help if i set my gain with a dmm and set it to like 1000 rms at 14 volts or something. itd draw less current correct?
 

Gold Member
Username: Delsole

Post Number: 1542
Registered: Feb-05
I feel pretty confident you can leave your heat on as long as you like with the car running with out hurting you batteries. With normal car equipment your voltage shouldn't drop below 12v. If it does i would bring it back.

On a lot of Ho alts they really don't shine until the rpm's get going(in between 1100-1500 and even higher to peak). some of them put out the same as a stock alt's at idle and i know those fluctuations are normal with a stock alternator.

I'm not sure what you have for a vehicle but some cars its very easy to turn up you idle. I wouldn't recommend unless you know what you doing but in your case bumping from 650 to say 900 rpm's might make the world of a difference.
 

Platinum Member
Username: Glasswolf

Post Number: 13629
Registered: Dec-03
http://www.glasswolf.net/papers/altspecs.html

like I already said, anything above 12.0 volts is fine. 12.7 is right where it should be at idle. The alternator output varies based on the pulley RPM which is directly proportional to engine and crank RPM since it's all tied to the drive belts. The faster the alternator turns, the more current it produces, and the voltage will fluctuate between 12.6 and 14.4VDC usually. 1200rpm+ is usually a charging voltage from the alternator.

yes I have several HO alternators, and all of them put out less voltage and current at idle RPM range.

set the gain to match the line voltage of the head unit and leave it alone after that.
 

Gold Member
Username: Tejcurrent

Post Number: 2243
Registered: Apr-07
I had several H/O alts that did that and it's b/s. Some higher peak output alts (not going to say cheaper) design things to put out more power at highway speeds by sacrificing idling output.

It has been my experience that 2 factory alts totaling 250 amps will do much better all around than 1 250 amp unit from some companies. I've had the same problem as you in the past, I would either switch alternator companies or ask them if you can switch to something with more output at idle.

If I had to order over again I'd stick with Mechman or DC Power.
 

Gold Member
Username: Tejcurrent

Post Number: 2244
Registered: Apr-07
^ Glasswolf, I feel that if you're sitting at the same voltage at idle as with your car off there is something wrong.

I've had cheap alternators do the same thing his is doing, and I've had good ones that kept 14-15 volts at all times. My factory never fluctuates between idle and highway speeds more than .3 volts.
 

Silver Member
Username: Wackzirth88

K-town, Il U.S.

Post Number: 391
Registered: May-09
Thats how I feel that my voltage shouldn't be the same with my car on and when it's off. Yes it is a cheaper one and does all things you described. I'm going to give them a call tomorrow and see about something with more output at idle.
 

Silver Member
Username: Skdooley

Roanoke, VA Usa

Post Number: 731
Registered: Oct-09
I agree with you Zack, if I was to purchase a HO alt it better be keeping things at or around 14 volts.
 

Platinum Member
Username: Nd4spd18

Philadelphia, PA

Post Number: 11075
Registered: Jul-06
GW is right as always, however DBE usually sends you a smaller than stock pulley with the alt, did you use it? They design the alt for that pulley not your stock one.

And stop listening to auto shops / alternator shops lol.
 

Silver Member
Username: Wackzirth88

K-town, Il U.S.

Post Number: 392
Registered: May-09
Yes I used it, they only sent one pulley and it was already on it. It had a little sticker on the pulley that said using this overdrive pulley will allow better output at idle. Thing is it's the same size pulley that's on my stock one that's why I asked the alt shop cause I figured it should be smaller.
 

Platinum Member
Username: Glasswolf

Post Number: 13635
Registered: Dec-03
Troy, it's not the alternator causing you problems if you're unhappy with the output voltage at idle, which by the way is normal, like it or not. The problem is your voltage regulator, since the alternator doesn't actually put out DC voltage anyway. If you want more manual control over your HO alternator, then get one with an external voltage regulator.

No alternator will put out the same peak current at all RPM ranges from idle to redline. It's simply how they work. The alternator functions based on the rotor speed, which is directly related to the pulley size and engine RPM. No matter what pulley you have, the alternator rotor is still going to increase in speed, and as a result produce more current as the engine RPM increases.
If you want to understand how an alternator works, see here:
http://auto.howstuffworks.com/alternator2.htm

You can get an alternator/regulator to put out 14.4VDC @ idle, but quite frankly, it really doesn't matter, since a: a lot of amplifiers use tightly regulated power supplies these days anyway, and b. if your amps don't use a regulated power supply then the truth is you'll never audibly hear the difference in power between say, 250 and 300 watts anyway (12 to 14.4VDC difference) It takes double the power just to hear a +3dB increase in volume.
 

Silver Member
Username: Wackzirth88

K-town, Il U.S.

Post Number: 393
Registered: May-09
i called dbe today and asked if there was anything i could do to increase the voltage at idle in gear. He said that it could be my belt is slipping and changing it might help. i asked if they had any other units that offered more at idle but they dont.
 

Silver Member
Username: Skdooley

Roanoke, VA Usa

Post Number: 734
Registered: Oct-09
I guess there are only a couple things you could do. Either one, get a new alt, or two, having a nice battery bank in the rear to maintain what voltage the alt is putting out. As long as it doesn't drop below 12, you should be ok.
 

Platinum Member
Username: Glasswolf

Post Number: 13649
Registered: Dec-03
http://www.dcpowerinc.com/

you can try these guys. they will give you what you want, but it's going to cost ya. Wrangler and Ohio Generator are good as well.
 

Gold Member
Username: Delsole

Post Number: 1545
Registered: Feb-05
I just ordered a 320 amp from dc power this morning. They said it will take about 3 days to make and should ship out friday. It seemed there was nothing but good comments about them. However i wont repeat what i paid because it hurts.

I guess they make a lot of alternators for the military. They also don't use any cheap made in china parts, and i believe they use mostly Denso cases(dont Quote me).
 

Gold Member
Username: Tejcurrent

Post Number: 2245
Registered: Apr-07
Glasswolf, you know what you're talking about and I wont argue that amperage drops with rpm, but voltage should be regulated around 13.5-14.5 volts on average. If the voltage is dropping below this general area it means the alternator is unable to supply sufficient power to the electrical system.

When the voltage becomes equal to or lesser than my batteries resting voltage I am draining my batteries. You say the difference between 12 and 14 volts is minimal, but it adds up. My amp is rated over 10,000 watts @ 2 ohms 14.4 volts. Now if I was idling at 12 volts I'd be expecting more like 8,000. That's a big difference that would result in a much lower score on the meter. While it might not be very audible, 2000 watts is more loss than most people have in their whole system.

I used to run Iraggi 380s, but after a few months in the summer my a/c was always hot in traffic because the voltage was dipping so low at idle, even with 4 alts running. I found out they put out around 10 amps at idle, meaning 50 amps to run all my electronics. My battery light would come on!

At highway speeds I was golden, but for daily driving it was not practical. I also had a powermaster alternator that would dip some, which was not acceptable to me. I used a MLA module for a while, and now I have a Powermaster voltage control module that will be set around 14.8-15v so I'm not worried about my electrical situation, just saying there's a real difference. You should not have your battery drain every time your car is stopped. The alternator should still be putting out enough amperage to sustain 13+ volts.
 

Gold Member
Username: Tejcurrent

Post Number: 2246
Registered: Apr-07
I've also heard nothing but great things about DC Power, they seem to make extremely stout products.
 

Platinum Member
Username: Nd4spd18

Philadelphia, PA

Post Number: 11076
Registered: Jul-06
If you have the correct pulely on it then i don't think theres anything wrong here. As long as you are never seeing below 12.5 volts you are not draining the batteries and the alternator is doing its job. Variations in the 13s are normal, alternators are not designed to hold 14 volts at idle all the time.
 

Gold Member
Username: Delsole

Post Number: 1548
Registered: Feb-05
I will hopefully be able to give a review within a couple weeks.
 

Platinum Member
Username: Glasswolf

Post Number: 13652
Registered: Dec-03
Troy I'm really not trying to be the bad guy here or even argue with you.
Even when the alternator (or regulator in this case) is putting out 12.6 volts or so, it's still supplying the current for the car and audio system. The only time it wouldn't is if the alternator's output actually falls below that of the battery. While I've preached about the fact that audio amplifiers never actually put out their rated power in real world applications, I will note that in most competitions, you're running on battery power anyway since the majority of sanctioned event classes require the engine be either turned off, or at idle when metered.
On a side note if you really want to have some fun, look into replacing your isolated audio batteries with some of the 16 volt racing batteries that can be charged from a 12-14 volt electrical system (really cool stuff, and they'd give you a 16 volt power source for metering in competitions.)

The issue with Iraggi wasn't limited to you. A lot of people complained about his build quality, which was why I stopped listing him in the good catagory of my companies page. Most alternators do drop in output at idle, but not like that. The drop is usually to about 60% of rated HOT output, as I believe I mentioned in the alternator specs page on my site, but I'd hve to check.

If you look at stock vehicle alternators you'll see that nearly every one in production will put out 12 volts at idle, and 13.8 above idle. That's just the way they are. It's not a defect.
 

Silver Member
Username: Wackzirth88

K-town, Il U.S.

Post Number: 394
Registered: May-09
I bumped the idle up a tad. Had to mess with it a bit but I finally got it where I'm happy with it. With the music at half volume headlights on the voltage sits at 13.6-8 at stops. In park at idle with the air or heat on at full bore voltage is around 13.5, 13.3 with lights n air at idle. Even tho u fellas said I'd be fine, I just feel better about it sittin in the 13s. Thanks for the input guys

also I didn't mention it in the original post but incase anyone was/is curious. The voltage at idle is 14.3-5 when I first start my car,drops down to 14.0-2 once the engine gets hot.
 

Platinum Member
Username: Glasswolf

Post Number: 13704
Registered: Dec-03
alternators have a Hot and Cold rating for output.
the Hot rating is lower than that of the Cold rating.
Your findings are most likely related to this fact
 

Platinum Member
Username: Glasswolf

Post Number: 13705
Registered: Dec-03
http://www.glasswolf.net/papers/altspecs.html
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