Most alternator maximum outputs are rated at a higher rpm than idle. In reality, you’re only getting the rated output for a very short period (WOT). They are generally rated at a 3-1 ratio. Many drag racers use 2-1 ratio to keep the alternator rpm within manufacture limits. A 100 amp rated alternator could easily be outputting less than half it’s maximum rating at idle depending on the idle speed of the engine.

Imho, an alternator for drag racing should have 2 gauge minimum for connection to the battery, be it run independently to the battery or attached to the starter cable.

just like in the old days. Would normally do a full field test to check max output @ 1K and 3K.

Supply and demand.

The OP still hasn’t told us exactly which alternator he uses and if it’s an ultra mini there’s his problem because it’s absolutely useless.

quote:

I run a pretty simple system Red top with a 48 amp alt. Small Delco. Never have i had to charge the battery.

48 amp alternator, no charge, That’s Impressive!!

My 12v system uses a 150 amp (2-1 ratio), and after running radiator fan and water pump for 5 minutes and then starting with all electric running (2 fans, pumps, headlights) and TB energized at idle, the led dash indicates 14.1v , same as the data acquisition when recording run. Probably reads slightly higher at battery with multimeter. I never charge between rounds or start of race day.

I run 2 12v and alternator. I very rarely ever put a charger on car.

Was able to load test battery today and held above 12v for 15 seconds at 200 amp draw, probably not battery. Im going to test battery chargers tomorrow or this weekend at the national.

Smokinchicken,

My original water pump (now my spare) was a Sherwood Aqua Tiger. Great pump by the way!

I thought that pump was bad, turns out it was a little low on water.

I pulled it and replaced it with a Dedenbear. It messed up this last year (it’s really old now) and I got a rebuild kit from Figspeed. It’s repaired and back on the car.

The step down box is an XS Power pn993 and it will step down 2.4 volts or 3.6 volts. I actually bought it from JR Baxter.

You could literally hear the water pump cavitating but it works great with the step down box.

Speaking of 16 volt batteries, I have a perfectly good (one season old) XS-D1600 I need to sell. I replaced it not realizing I just had a bad connection.

Would prefer not to ship it, could bring it to Dallas for the double divisional next month.

250 bucks

I have a Ultra Mini 75 amp that Mark Payne built me that is not useless. I always charge between rounds and never not had the car start multiple times even hot lapping and double entered.

I also have a 11" Spal fan that I run to cool down with charger on.

Check your charger. If you have a digital gauge for volts in your car then hook up the charger and see what it is putting into the battery. I have been told anything under 17v means charger is not putting enough into your battery. This may be why the battery cant keep up.

Tony, I’m surprised to hear you feel it’s helpful as I don’t know anyone that has run an ultra mini that still does including me because it just doesn’t charge at a high enough rate to keep pace with the demands going down track. I know that ECAE only recommends their 55 amp unit for those running alcohol with the cooler engine temp negating the requirement for the fan to run constantly.

I have an ultra mini Powermaster alternator and I rarely put battery on the charger on race day. It has worked great and I recommend them. The Powermaster starter I have is the best one I have and my Tilton Super Starter is now my back up. Now in my trailer I almost always keep battery on a trickle charger and it seems to help life of battery.

I do believe in running a good alternator and it is a good idea to charge on race day even though I usually do not.

As for 16 volt batteries they really are not any better only different. They have about same amount of total energy to start your car they just dump it faster. So it does spin it over faster but will also go dead faster. Most of the time not a problem. I ran 12 volt system for many years with no problem then I had a ground issue problem and fixed it.
Wanted to try the 16 volt deal and it is okay and does spin it faster if that is what you need.
My new car I am building is back to 12 volt system really nothing against 16 volt they just are not any better overall in my opinion.

I have not had any problems with fans or water pump with my 16 volt system.

When the 16v charger is hooked to the car, how many volts should I see on my digital gauge to know that it is charging?

quote:

Originally posted by 1320racer:
Tony, I’m surprised to hear you feel it’s helpful as I don’t know anyone that has run an ultra mini that still does including me because it just doesn’t charge at a high enough rate to keep pace with the demands going down track. I know that ECAE only recommends their 55 amp unit for those running alcohol with the cooler engine temp negating the requirement for the fan to run constantly.

I told Mark everything I run and he said he could build the Ultra to a max of 75amps which would run everything. I have never had an issue but also wasn't aware the standard mini can now be used in the Moroso Vacuum pump/Alt mount that I use, had I known that before I ordered this one I would have went with a 120 or 150 mini....

quote:

Originally posted by SmokinChicken:
When the 16v charger is hooked to the car, how many volts should I see on my digital gauge to know that it is charging?

Ok so to narrow this down, you have load tested the battery and it was good, so that eliminates that so to say. Now with the charger hooked to the car you should see 17.25 or 17.5 to charge the battery essentially. if your not seeing that then its not charging. Now on the other hand, if you have the charger connected to the car with the fan running you should still see 17.25 or 17.5 anything less and it isn't charging or keeping up with that you are running. So in a nut shell, if you connect the charger to the car and turn any accessory on you need to see the above charging volts or its not charging.

Mark is a great guy, knows his stuff and builds great products, I run his starters.

quote:

Originally posted by Bucky:

quote:

The principle that a motor uses less current at a higher voltage only applies to AC motors.

Indeed. I have seen the false argument about power consumption with 16V forever.
When you run the fan on 16V, it turns faster than it did on 12V. Does that take more or less work? 16V isn't magic, so of course it is more work, and consumes more wattage. It's just that simple.

Ohm's Law. P=IxE, where P=Power (Watts), I=Current (amps), and E=Voltage. The fan's resistance should be fixed, so if it draws 12 Amps, it would use 144 watts at 12 volts, and 192 watts at 16 volts.

quote:

Originally posted by FootbrakeJim:

quote:

Originally posted by Bucky:

quote:

The principle that a motor uses less current at a higher voltage only applies to AC motors.

Indeed. I have seen the false argument about power consumption with 16V forever.
When you run the fan on 16V, it turns faster than it did on 12V. Does that take more or less work? 16V isn't magic, so of course it is more work, and consumes more wattage. It's just that simple.

Ohm's Law. P=IxE, where P=Power (Watts), I=Current (amps), and E=Voltage. The fan's resistance should be fixed, so if it draws 12 Amps, it would use 144 watts at 12 volts, and 192 watts at 16 volts.

That could be true, but not for an electric motor that turns faster and consumes more power with higher voltage. Ohm's law does not work that way here.
Is the fan turning faster or not? Yes it is? The it is consuming more watts.

All I will say about this is I had to replace 2 fans because they burned up. I cured it by installing a turbo start step down module Problem solved..lol

Dave

quote:

Originally posted by David Covey:
All I will say about this is I had to replace 2 fans because they burned up. I cured it by installing a turbo start step down module Problem solved..lol

Dave

I wonder if a simple resistor would work in that case too?