Adventures in data logging

May 28, 2019, 01:48 PM

OK so you have the 1 wire alt with a 4ga cable that runs directly to the batt, no cutoff inline?
I know it's not much difference but I guess your battery is getting lower throughout the day and that's the increased amperage from 1st to last run. You're on methanol aren't you, so you're not running the fan much even between rounds.
I put a charger on between rounds while running the fan and water pump and I run a 1 wire alt. I charge to stop the discharge of the battery causing the load on the alt. Also feel it increases battery life.

May 28, 2019, 02:21 PM

banjo

It is a 3 wire alternator with sense wire hooked to my main power distribution point.

I dont have a cutoff. Alternator is wired directly to battery. My understanding is that you can fry your alternator disconnecting it when it's under load.

Currently the sensor is on the the alternator wire. I am going to move it to the main power wire. Curious to see if I get any different readings. I always though that the alternator carried all the load. But for the battery to discharge, that would indicate they are sharing the load. I guess that makes sense, as two batterys hooked in parallel share the load.

I also think part of the problem is the car doesn't run long enough to keep the battery top off. I have never had any issues with a dead battery, so I think the amount I'd charging is small. It's definitely not enough to a difference in et.

I do put the battery on a battery tender during the week to ensure it is topped off.

May 28, 2019, 02:25 PM

banjo

It just occured to me that I leave my o2 sensor on all the time. That is probably where the discharge is coming from...

May 28, 2019, 03:08 PM

nomad

quote:
Originally posted by banjo:
It just occured to me that I leave my o2 sensor on all the time. That is probably where the discharge is coming from...

I never shut off the batteries when I'm at a race. I have a master cutoff mounted on the steering wheel.

I also run a three wire alternator. It's a 12 something Delco. It's 100 amp and puts out 14.8 volts at idle. It needs the throttles winged to be sure it charges.

Like you the RacePak is on all the time. I charge between runs, too. A run isn't enough to keep it charged given all the equipment we now run.

I don't think those O2s drain enough to kill the battery between runs.

May 28, 2019, 04:45 PM

banjo

Definitely dont think it's enough to kill the batteries between runs, just trying to under why the alternator was working harder the last run. I am going to charge it when I can between runs.

I know in the past when I have had cells go bad in the batteries, it would mess with et, curious to see what the amp meter shows.

May 28, 2019, 09:42 PM

Eman

You should check to see just how much is being drawn when the car is parked.

May 29, 2019, 11:11 AM

banjo

Good call. That will be easy to do.

May 29, 2019, 01:49 PM

Eman

One thing I've seen on cars with PG's and a spring loaded type solenoid the solenoid stays hot when the car's power is on. Just the way some wire it and I would want to wire it differently if it were mine. I have a 1 wire alt. and the only time I had any problems was when the alternator itself became a draw on the battery.

June 11, 2019, 04:12 PM

Mr498

Well since my last post here I put a new alternator( 1 wire, 100 amp.) and changed the pulleys from 4" to 5" on the crank and 2.75" to 2.375" to get the desired 2 to 1 ratio. It ran worse, running 9.70's when it should be going 9.40's, missing all the way. so after 1 pass I decided to disconnect the alternator and see what happens. Low and behold it runs 9.40 with no miss. At the time thinking it's either the alt.(new) or the charge wire(10 ga.) on the car since I bought it (18 years). So I'm going with 6ga. charge wire and while looking at the routing I forgot I put one of those moroso alt. disconnect relays on there(to shut power off when the master cut-off is off). Now wondering, since the alt. wire goes through it can it cause problems?

June 11, 2019, 04:55 PM

banjo

Fire the car up, turn everything on and do a voltage drop test. Set the voltmeter to volts, put one lead on the alternator terminal, and one on the battery and tell me what it reads.

Also did you charge the battery?

How much voltage does it show at the battery at idle?

June 11, 2019, 06:59 PM

Mr498

Thanks banjo, will do those tests after I change the wire. Reason I asked about the alt. shut-down is because different routing and terminals. btw do run one of those shut-down relays?

June 11, 2019, 08:46 PM

banjo

Be curious to see a before and after if you can.

I do not run a shutoff, it's a homerun shot from the alternator to the battery.

June 12, 2019, 03:16 PM

adv ET 266

I have a spare Edelbrock Quikdata Advanced Box for sale cheap. A friend has a wiring harness and it’s also available. One of the original and best data collectors ever made.
Message me if you want it

June 12, 2019, 03:45 PM

Triple Nickel

1 wire alternators and other configurations that are "hot wired" to the battery or main power supply will draw voltage at all times in order to keep the alternator "turned on". In my case, i had my 1 wire alternator hooked to the battery side of the master kill switch so that the car would shut off when the master power switch was turned off. The only problem with this is the draw that the alternator always places on the battery. Always leads to a dead battery if you leave the car in the trailer for a few weeks without charging.

My solution was to run the 1 wire alternator through a continuous duty solenoid that's triggered by a switch on the switch panel. This way the alternator is totally disconnected from the battery and the activation wire is no longer hot and drawing electricity from the battery.

I also think this kills 1 wire alternators as its never ever "turned off" unless you disconnect the wire from the alternator to the battery which i never did because its just too much trouble.

Moroso makes some pretty cool master disconnect switches that would eliminate the need for the solenoid i used but it was a little easier for me to install the solenoid than swap out the switch.

June 12, 2019, 06:45 PM

BP758

quote:
Originally posted by Triple Nickel:
1 wire alternators and other configurations that are "hot wired" to the battery or main power supply will draw voltage at all times in order to keep the alternator "turned on". In my case, i had my 1 wire alternator hooked to the battery side of the master kill switch so that the car would shut off when the master power switch was turned off. The only problem with this is the draw that the alternator always places on the battery. Always leads to a dead battery if you leave the car in the trailer for a few weeks without charging.

My solution was to run the 1 wire alternator through a continuous duty solenoid that's triggered by a switch on the switch panel. This way the alternator is totally disconnected from the battery and the activation wire is no longer hot and drawing electricity from the battery.

I also think this kills 1 wire alternators as its never ever "turned off" unless you disconnect the wire from the alternator to the battery which i never did because its just too much trouble.

Moroso makes some pretty cool master disconnect switches that would eliminate the need for the solenoid i used but it was a little easier for me to install the solenoid than swap out the switch.

Question.
On a one wire system, when it’s fired up and has output will taking away the hot wire take the load off or does it stay energized until it stops?