t-von

iTrader: (8)

Ok I've been having some hard hot starting issues for quite some time as I have a Braile battery in the rear bin of my Fd. On another thread I was told to install some diodes to help boost the voltage output because apparently AGM batteries need 14.5 volts or better to charge properly. The alternator I have charges fine at idle as long as there isn't too much load on it. Volts hold steady at 14.0 when warm but as soon as the fans kick in, voltage drops to 13.0. If you add the headlights with the fans, it drops to 12 volts. This is a problem! When the voltage drops this low, the AGM battery isn't getting enough energy to properly recharge and is causes too much voltage drop during hot starts. Well since I have always measured voltage on my Haltechs gauge page, I assumed that's what the voltage always was. Well before I installed the diodes, I decided to check the output at the alternator. Well apparently my alternator is over charging and putting out 17.10 volts at idle zero loads. I check the volts at the battery and it show 16.9 volts. Now I have an 8 gauge wire that runs from the battery to the Haltech in the passenger foot well compartment to power the fuse panel and relays. When I check volts at this location, I get 16.8 volts. I also checked the the outputs on all 3 relays (Main, Fuel, and Ignition) and all outputs show 16.8 volts. Now aside from me needing another alternator, my Haltech gauge page only shows 14.5 volts and is reading 2.5 volts lower than actual. So is there something I can do to get the Haltech to read the actual volts? This voltage discrepancy is effecting my injector dead time tables.

RENESISFD

iTrader: (13)

I dont understand what you are saying regarding charging voltage.

In the first part of your paragraph you mention low charging voltage of less than 14 volts then in the latter part you mention 17 volts?

Or is this before you added diodes? Your alternator is undersized or under driven.

jetlude

iTrader: (9)

Where exactly in the circuit did you add the diodes and what are the values of the diodes. Mind linking the ' other thread'

Thanks

j9fd3s

iTrader: (3)

http://www.haltech.com/wp-content/up...ng-Diagram.pdf

are you checking the voltage at the switched power? (20A fuse in the fuse box, red/white wire) weirdly it looks like the ECU doesn't have a B+ wire, only switched power.

t-von

iTrader: (8)

I was just giving some background on how I found the voltage discrepancy. The low charging voltage only happens when you turn on the fans and lights. So I know my alternator is undersized and will be upgrading soon. I was gonna experiment with the diodes but never did because I was finally measure the volts coming out of the alternator before installing the diodes. 17 volts is what it's showing but I only read 14 volts on the Haltech gauge display. I had to over drive this alternator to get it to put out enough amps at idle. The alternator is suppose to be an 160 amp upgrade I got off ebay. Apparently after doing some research, no one sells the parts to truly upgrade the fd alternator so this alternator is only putting out stock amps. I also found out that these supposed upgrades actually put out less amps at idle compared to a factory stock alternator. Anyways, I'm just trying to figure out why the Haltech is reading so low and what I can do to fix that?

t-von

iTrader: (8)

Yes because that's the main haltech power feed. I also checked all the relays to make sure they all match (which they do). The Haltech display is show 2.5 volts lower than what the actual input voltage is.

t-von

iTrader: (8)

1st post this page #576.


https://www.rx7club.com/20b-forum-95...1067848/page24


Monsterbox and myself were having hot starting issues and the thread build went into a discussion about charging voltage.

I've since figured out my hard hot starting issue. I know it's related to my weakened battery from all the minor loads that this shitty alternator can't keep up with. My 20b has 6 IGN-1A ignition coils, two fans, a single fuel pump. When I turn everything on max "blower motor, A/C button is wired to turn the fans on automatically, HID lights) my charging volts drop instantly. So I will buy a REAL upgraded alternator soon. I just need to really figure out the voltage discrepancy with the Haltech.

j9fd3s

iTrader: (3)

i assume you looked at the ecu connectors and the pins and stuff. i would try reloading your map from the default map, and then if that doesn't work, maybe reloading the firmware, then the default map and then your map?

if that doesn't work, you can either map around the voltage just being wrong, or replace ecu and recheck.

t-von

iTrader: (8)

I had already done a firmware update just a couple weeks ago because my old Dell laptop's serial port was loosing connection and corrupted my most recent tune. So I had to re-tune my engine yet again from an eariler map I have saved. My new laptop uses a usb to serial adapter. From now on I will be saving maps on a flash drive as a backup.

t-von

iTrader: (8)

Damn I feel like a dumb ***! Well it turns out the discrepancy was due to the multimeters low battery. My main multimeter had a dead battery so I was using a cheapy I had laying around. Well it turns out the cheapy multimeter doesn't have a low battery indicator like my other meter and reads inaccurate with a low battery. My haltech is fine and so mods you may delete this usless thread.

RENESISFD

iTrader: (13)

LOL

That sucks. I had a simmilar problem with a cheap multimeter. Was showing incorrect voltage. Spent 3 hours wasting time because of bad data. I now only use quality meters for that reason.

jetlude

iTrader: (9)

Glad to hear you that the voltage is fine.

My haltech normally reads about 1/2 volt less than my greddy t/timer which also reads battery voltage. At this point I am not sure which is correct, but I don't worry about it .

t-von

iTrader: (8)

The little things seem to always get us. Lol!.

RENESISFD

iTrader: (13)

^ Yes I had a great time smashing that meter with a hammer.