Try 3 batteries, you can always take 1 out.

I have one 16 volt XS battery and a 100 amp 16 volt alternator with a 2:1 ratio pulley. Never charge between rounds and never have any issues starting the car. I start the engine with the ignition switch on and everything else off. Once it starts I switch the fuel pump, water pump and electric fan on.

The XS battery I'm using is more than four years old. During the week I use the XS Intell-Charger 7/24 at 5 amps. In fact it's been charging for months, don't know if this is a good idea but I never turn it off.

Bob

quote:

Originally posted by Phil Dees:
Try 3 batteries, you can always take 1 out.

Ha! Be aware that if one battery fails, the system won’t work properly until the faulty battery is removed.

quote:

Originally posted by Stephensx04: If you are dead set on not putting an alternator in then I would look into 2-6 volt batteries in series. Will get far more amp capacity than 2 - 12 volts in parallel.

Imho, this is how I would run two batteries (6v) in series not using an alternator. MUCH long lasting power. I know a racer that uses one 6 volt and one 8 volt battery in series without an alternator and doubles.

I had an alternator and 2 batteries in the trunk. My Nova was inconsistent and it took me a while to find it. Gauge read 12.9v sitting and 14v with the engine running. But the grid data showed what was going on. When it would shift, the voltage would drop to 10v and struggled to get back to 12v the rest of the run. I put a new 140 amp alt on the car and straightened it right out.

The old 100 amp alt just couldn't keep up with the demands.

electric gauges (oil, water and trans temp)
water pump drive
fan
delay box
electric shifter
single stage nitrous on a timer

Doesn't seem like too much to me.

If using a 100 amp rated alternator consider selecting 4 gauge wires. My alternator is 150 amp rated and I use 2 gauge wiring, same size as the starter wiring. I join the alternator wire to the starter and share the same wiring going back to the battery. Correct alternator wire sizing is important. Here’s a chart from Powermaster.

Well last night we fired my engine up for first time after a bunch of changes and upgrades. One being a mechanical fuel pump. 16v XS 1000 with powermaster alternator. Had prob 4 starts getting timing and fuel pressure set ran 2.5 gallons of fuel and approximately ran about 10min to get it warmed up. Tried to restart it after that 10min 16v battery wouldn't crank it over 582ci. Kid was in car and forgot to ask him to verify the voltage on racepak dash.

Threw charger in it assuming it was the changes to the alternator. The alternator has an adjustment on it and last year I had it set as low as possible with electric pump. And I changed pulleys this year so figured it needed turned up.

Adjusted screw up on alternator. Fired it up, had 18v now. Ran for about 5 min. Tried restarting several times no issues. Put charger back on it and it went to float (full charge) after about 3min.

Point is I'd never trust not running with alternator. That little bit of run time without any fans or electric fuel pump wiped out my new xs1000.

After with alternator working it stayed charged and restarted the car several times.

In my opinion - voltage and amps - in a game where we try to eliminate variables is not one to play with....

Alternator cause its not 1970 anymore...

Another foot stomp for having an alternator that can cover system load at idle. If it can not, it will charge going down the track and potentially cause consistency issue.

My choice for an alternator is a stock cs130 from oreillys. Been running one for many years and an I think i have only have to replace it once. Under warranty. It nice being able to run down to the local parts house to replace if needed. I selected this alternator based on its idle capacity.

Another thing to consider is running a 3 wire setup. Especially if you have a long wire run between your alternator and your main power distribution point. A one wire alternator regulates the voltage based on what it sees at the alternator, where the 3 wire regulates based on what it see at the wire. It will account for all the voltage drops and respond better to load changes.

Wire size and pulley ratio are critical.

An alternator looses efficiency the closer it gets to max capacity. This can causes issues with consistency. The cs130 alternator that I have is rated at 105 amps. I believe the alternator is rated at 60 amps at idle with a 2 to 1 pulley ratio My max system load is between 50 and 60 amp. And normal operation, its in the 25-30 amp range.

I have a load sensor on my alternator where I log the output. When I had my alternator go bad, I could see in the Logger that it was failing. It was intermittent at first and it was causing consistency issues. I can also tell when the battery is getting off of full charge which very rarely happens.

Easy way to tell if your is keeping up is put a voltmeter on the battery, start the car and idle. Start turning things on. If the voltages starts dropping, you probably dont have enough alternator, insufficient wiring size, or incorrect pulley ratio. I wouldn't want any less than 13.5 volts with ,mine car stays at 14 volts.

Good luck

quote:

Easy way to tell if your is keeping up is put a voltmeter on the battery, start the car and idle. Start turning things on. If the voltages starts dropping, you probably don't have enough alternator, insufficient wiring size, or incorrect pulley ratio. I wouldn't want any less than 13.5 volts

Agreed! This is the best way to determine the charging voltage present at the battery using a digital handheld meter. After starting, monitor for up to a minute.

I have four different devices recording or displaying battery voltage in my car. No two agree… all are different to within 0.6 volts. All four devices located up front are on their own separate power feeds from the rear mounted battery.

MSD Grid will show the idle voltage of 13.6v . The digital V-meter display attached to the relay board Fused Battery terminal output reads 13.7v at idle. Holley HP ECU shows 14.0v at idle and Holley 6.86 Digital ProDash displays 14.2-3v at idle.

Why different? Probably voltage drop of where the device is located from the battery and how much power it’s drawing. Accuracy might be part of it.

Trust your multimeter measurement at the battery for what voltage your charging system is outputting at idle.

I use a CS130 alternator. Still provides full charge at lower rpms unlike the older 10SI alternators.

If you have a lot of electronics and electrical devices in the car, you want that extra voltage.

The key reason I re-installed an alternator is to supply power to all the electrical devices I'm now using, and the list is long.

When you add up the voltage demand to drive the MSD Digital AL7 ignition box, the Grid, the fuel pump, the water pump, the electric fan, the front and rear lights (At night), and of course to start the engine an alternator make perfect sense.

Any performance loss due to the weight of the alternator or the horsepower it takes to spin the alternator is really a minor loss. The gain from having sufficient electrical power is major. This is dial-in bracket racing, not top fuel.

Bob

Seems like I remember someone makes a cable driven mechanical fuel pump. I wonder if anyone makes something similar for an alternator? I really want to run an alternator but there is no room or way to make standard one work on one of my altereds and I think running it off rear end is not a good idea.

One of the reasons I thought a 3rd battery would be good, is it would put more weight directly over the rear wheels. Sometimes at my home track, my footbrake car will show more 60 foot variation than I think it should. It's a foxbody and I'm guessing that 57% or maybe even 58% of the cars weight is on the front. Getting that down to 53% front would help with consistency.

quote:

Originally posted by 62Galaxie:
One of the reasons I thought a 3rd battery would be good, is it would put more weight directly over the rear wheels. Sometimes at my home track, my footbrake car will show more 60 foot variation than I think it should. It's a foxbody and I'm guessing that 57% or maybe even 58% of the cars weight is on the front. Getting that down to 53% front would help with consistency.

How about three batteries AND an alternator? Take care. Tom Worthington

quote:

Originally posted by 62Galaxie:
One of the reasons I thought a 3rd battery would be good, is it would put more weight directly over the rear wheels. Sometimes at my home track, my footbrake car will show more 60 foot variation than I think it should. It's a foxbody and I'm guessing that 57% or maybe even 58% of the cars weight is on the front. Getting that down to 53% front would help with consistency.

I raced a 1988 Fox body for 3 years for a car owner on a 28x10.5 tire. The car was absolutely deadly & one of the best cars if not the best I ever raced.

I will say this, we ran the car with a single battery, alternator & the proper bolt on suspension with tuning. The 1st year out with this new car. I entered 8 races, won seven of them including a Wally & the other race I took 2nd place.

If you're worried about the weight bias, add ballast to the rear; but run an alternator.

2BKING

What bolt on suspension did you use, what was car weight, eighth mile ET?

HPM megabite jr. upper & lower control arms. Car was 2600 without me/2800 with me if I remember correctly. It ran 6.30s 1/8th mile & 10.0s 1/4 mile.

2BKING

This message has been edited. Last edited by: B KING,

quote:

Originally posted by markemark:

quote:

Easy way to tell if your is keeping up is put a voltmeter on the battery, start the car and idle. Start turning things on. If the voltages starts dropping, you probably don't have enough alternator, insufficient wiring size, or incorrect pulley ratio. I wouldn't want any less than 13.5 volts

Agreed! This is the best way to determine the charging voltage present at the battery using a digital handheld meter. After starting, monitor for up to a minute.

I have four different devices recording or displaying battery voltage in my car. No two agree… all are different to within 0.6 volts. All four devices located up front are on their own separate power feeds from the rear mounted battery.

MSD Grid will show the idle voltage of 13.6v . The digital V-meter display attached to the relay board Fused Battery terminal output reads 13.7v at idle. Holley HP ECU shows 14.0v at idle and Holley 6.86 Digital ProDash displays 14.2-3v at idle.

Why different? Probably voltage drop of where the device is located from the battery and how much power it’s drawing. Accuracy might be part of it.

Trust your multimeter measurement at the battery for what voltage your charging system is outputting at idle.

I made that mistake on my Nova. Trusted the voltmeter at idle and had a gauge in the trunk so I could monitor voltage with the trunk lid off.

Everything was normal and in the green where it should be, the grid data acquisition showed this not to be true going down track.

I think we're limited to 2 batteries? At least according to IHRA rules.