Wondering if anyone else ever had a voltage drop at high rpms , my car at idle and normal driving conditions is fine 13.8-14v and idle and with all the loads its fine , but last event i went to the track and checked my voltage log and it read as low as 10.8v at 9900 rpms , belt is tight , car is on aem i know on the aem it might read a bit lower but never seen it that low . vehicles electrical pretty simple dual 044s and regular 12 inch electric fan , just wondering if its a sign of internal regulator taking a crap

 

you are running off your battery at that point! we had the same problem with kubo's car! you need a higher amperage alt. add up all the electoronis (amperage dram) you have in the car and see if it matches or exceeds the alt amperage! 140 amp ftw!

 

thanks for the info any reliable company that i can get it done ? back in the day i used to have crx and had my alt beefed up for a sound system and i had nothing but problems with aftermarket alternators thanks

 

Mine never drops below around 13.5 and I am just using a stock style battery from auto zone that is mounted in the trunk. About the worst case possible. I have seen people have issues with the super lightweight batteries. Get the alternator checked out. The stock one should be fine unless you run a really wimpy battery.

 

You make a good point i really only started to have issues after using one of those small oddosey batteries . but the voltage on the battery is fine i can see that happening if the battery is shorted and as soon as u shut off vehicle not restarting , needing to jump battery ,but battery is good

 

i am switching out my little odyssey for a full size battery for that reason. my voltage always dropped at high rpm. i also need more power for cooling the car down between rounds.

 

did u notice after switching to the odyssey battery is when u started to have voltage issues?

 

idk what it is with aem and low voltage. i know of atleast 2 other cars that have issues.

 

I see the voltage drop issue in the high rpms when the alternator's wont load test good. I have seen it with the smaller gel cell batteries as well. Its not an AEM issue, I have had it happen with s300/FAST/Power FC on hondas.

 

i don't know, i've only used that battery. we'll see if it gets better this spring.

 

I had the same issues when i used one of those odessey batteries then i switch to a full size gel battery from napa and it was all fixed till world cup when my kill switch shorted out inside and stopped letting the alternator charge the battery.

 

i was only saying that jeff because of barones motor and issues with tommy's car.

got me scared, now, im goin back to look at my logs.

 

odessey batt suck! we had that problem with the s680 from xs power which is a great battery! we added up our estimated amperage from all our electronis we were using in the car and we were over by 15 + amps! the car began to run off the battery rather than using the alternators power to run the car! we now use a 140 amp alt!

 

how much did that alty cost you A Train? a place nearby wnat 300 or so for a 175amp alternator

 

recently purchased the 200 amp alternater from http://www.nationsautoelectric.com/highoutput.html
for a stereo car! and they have 140 amp available i didnt get a cost!

 

I also had that problem, it happened under full on the higher gears not enough alt. You can do a high output alt or a cap like for the stereo systems

 

You don't need a bigger alternator, just a decent size battery.

 

I've been using the optima 51r with no issues

 

Sounds like you are running straight off the battery. You sure the alt you have is working?

We went through the same thing when we made the retarded decision to switch from 16v to a little 12v. Those little batteries are a joke, alternator or not.

 

you can run a 16v battery with no problems????

 

Had that happen on the dyno because of my alternator, the AFR went crazy. I have it on a dyno sheet, I don't remember what it went to, but it wasent cool..

 

with a multimeter it reads 14.3 v at idle amd with loads on electricfan and wipers and headlights it reads 13.4-13.7 on the logs it shows fine up to lets say 4k then after that it just drops after the end of the run it shows normal charging voltage on the log

 

I do not mean to thread jack but could a bad battery cause a car not to start? I am getting 12v through out the car but its not sparking. I have changed all of the typical things that would keep it from running.

Here is a link to all of the problems i am having with my car

http://hondaswap.com/civic-del-sol-e...r-swap-422829/


I am running a odyssey pc680 battery and if i keep it off a charger for longer than 2 days it dies.

 

when you have a race car its all about saving weight. danny i agree with you a good battery is a great choice but ask any of the major teams guy like for say rado, you can start the car with a jumper pack and run the car on a damn dewalt battery if the alternator is up to spec! a bigger battery with more capacity is always good but you will get some sort of voltage drop! you dont want that! gary kubo told me you want the alternator to be able to provide the amperage for all of the electronics in the car other wise you are running off the battery at higher rpms. Ive been in the stereo field before i got in to this **** i know what im talking about! amps are the key! voltage is just a way to cheat the process.

 

I may be wrong, but aren't the AEM maps setup to turn the alternator off after 4k or 5k to reduce load on the engine and make more power? On a street car it may never be noticed, but on a 1/4 mi pass where it is above that point the whole time, it could be an issue. I believe an RSX I tuned on AEM was having this problem as well.