charging issue, not sure what related to

Spawne32 · Post by **Spawne32** » Fri Feb 24, 2012 3:01 am

Hey guys, im having some issues here that I really cant pin down that I want to know if its normal or not. Ive been through a total of 3 alternators in the past 6 months. Had an original nippondenso that worked fine, aside from the fact that it was old, bought a reman from maniac electric motors that worked just great, but it developed a short in the voltage regulator in the battery light circuit, but still charged normally. Currently im on a 130amp high output alt from maniac electric as well, with a full 4awg positive alt cable, brand new oem battery terminal \"cable\" with all the main cables, and 2awg and 4awg grounds across the car in various positions. Last summer I noticed an issue when all the accessories in the car were on, the charging rate would drop down to between 12.1 to 12.5v at idle, only above 1000rpm would the rate start to climb back up. I had assumed this was due to a aging 200,000 mile alternator, so I replaced it, with a very well made reman unit. Everything worked fine, but I had the same issue, charging rate wouldnt hold with all the accessories. I checked a bunch of things, disabled alt control in ectune, did nothing, ELD showed .55v in ectune under full load, which seemed normal, disabled the ELD in ectune, nothing. So that in mind, after a month of trying to diagnose what the issue could possibly be, i decided to go with a 130amp upgrade, did all the necessarily upgrade work to the wiring etc. Installed the unit the other day...guess what...12.5v when its fully loaded. When i tell you i was cursing up a storm, you would not believe. The re-manufactured units are only 88 bucks, I paid 190 dollars with shipping for this 130amp alt, and about 30 bucks in cable and connectors to upgrade this positive cable, not to mention all the other wires. I cant figure out for the life of me what is causing this voltage to drop so low when fully loaded, what annoys me even more is the fact that when i referred to my honda service manual just the other day, it says this is completely normal. The honda testing procedure for load testing an alt says at 60amp the charging voltage should be between 12v-13v, that makes absolutely no sense whatsoever. Not to mention the fact that this is a 130amp unit that should be more then capable of providing voltage to a otherwise stock car at full load. Ive run the possibility that the JRSC alt pulley may not be spinning the alt fast enough, but compared to the stock size pulley for the alt there seems to be absolutely no difference whatsoever. The other other thing I can think of is that the ECU is not sending the proper signal for field rate back to the voltage regulator for \"high output mode\". I do have several issues with brittle wires around the ecu area that are due to be fixed this month, but i mean really...could that actually be the cause? Not sure what to think here and not sure if its related to ectune directly or not. Im running a P75 ECU with a demon, and the ECU has already been replaced once.

Bindegal · Post by **Bindegal** » Fri Feb 24, 2012 3:37 pm

I have seen similar problems from the simple issue of an old/faulty ground wire from generator to block... /Allan

Spawne32 · Post by **Spawne32** » Fri Feb 24, 2012 3:38 pm

yes but there is no ground on the alternator

Bindegal · Post by **Bindegal** » Fri Feb 24, 2012 3:41 pm

Might not be a wire but there will for sure be a ground connection somehow. IÂ´m guessing voltage drop from either the power connection or ground. /Allan

Spawne32 · Post by **Spawne32** » Fri Feb 24, 2012 3:42 pm

the only ground that i know of comes off of the ELD/fuse block

relic1 · Post by **relic1** » Fri Feb 24, 2012 9:53 pm

trans to chassis ground wire

Spawne32 · Post by **Spawne32** » Fri Feb 24, 2012 9:54 pm

brand new, but ill double check the contact again tomorrow

JaredKaragen · Post by **JaredKaragen** » Sat Feb 25, 2012 12:00 am

Measure from battery ground to all the points where grounds meet parts, look for a voltage of less than 1v for it to be acceptable. This is a \"voltage drop\" test.

barry · Post by **barry** » Thu Mar 01, 2012 2:42 pm

you wouldnt happen to be running some hardcore amp and stereo system in your car would you?

Bindegal · Post by **Bindegal** » Thu Mar 01, 2012 3:53 pm

IÂ´m guessing you need to find the wire/wires with that illusive \"voltage drop\". The thing is: As the engine is running and the alternator should be charging the battery, something between those 2 points is introducing some kind of resistance. What surprises a lot of people is the fact that a wire or connection that looks just fine, can cause the problem. Measuing anything - like ohms - with engine off is useless. So get the engine running and start measuring where that voltage drop creeps in. If battery voltage starts good @ 14.2 volts or similar - and then drops, there will probably be a ground or power wire somewhere thatÂ´s gone bad and will - under load - even feel warm to the touch, as the energy from the alternator needs to go somewhere. /Allan