Should a 16 volt alternator be used with a 16 volt battery or just charge between rounds?
I had done it both ways. The XS "D" series will go several rounds without charging. [the full-size battery]
When racing without an alternator I keep the charger on whenever possible. In the later rounds, I do a 5 - 10 charge when time allows. I have won a 9 round race following this method.
7959,I used to run a full size 16 volt w/o an alt.,when you get to later rounds,round robin,it never let me down but wasn't spinning as fast.A year ago I put an East Coast alt. on,I will never run w/o one again! I can run 2-days w/o charging.
Ive raced a number of years running heads up and index racing on a D1600 battery with no alternator. Granted not bracket racing and usually had some time between runs to charge.
In 2016 I decided to add an alternator. Largest I could fit on this was a CS121 case #8078 Powermaster XS.
Never was happy with the output even though it was rated at 100 amps. But that's peak, not what it does at idle.
With no alternator the data logger shows constant 16.5 volts. Add the alternator, still only shows 16.5 volts. Should be charging at 18.5+ volts.
Just sat down and compiled the draw of my cars electrical system.
Grid 2.25 amp idle
13.87 amp at 7500
Magnafuel 500 17.3 amps
Spal 12" fan 29 amps
Meziere water pump 16 amps
so at idle the system draws 65 amps and at 7500 rpm it draws 76 amps.
I just contacted one company to see if they can increase the output of this alternator, but somehow I have my doubts. If not, I'll just take it off along with the large power cables and save the 15-20 lbs and go back to charging again.
So my advice is do your research on your system draw and buy the largest amperage alternator you can.
If your Meziere waterpump is drawing 16 amps it is fried! I would also think the same about your fan. Waterpump on 16 volts should be less than 10 although I never checked one on 16 only on 12 and they are around 5-6 amps that way.
Those were calculations based on 12 volts. Amperage draw goes up when going from 12 volts to 16 volts if I'm not mistaken.
Rated amperage draw on the water pump is 12 amps per Meziere.
Maybe I missed the 12 volt to 16 volt conversion for amps.
12 volt amperage per the manufacturers...
MSD grid idle 1.69 amps
Grid at 7500 rpm 10.4 amps
fuel pump 13 amps
fan 21.8 amps
water pump 12 amps
EDIT: checked the math and it should be correct.
for example, 12 volts at 10 amps. 12v/10 amp = 1.2 ohms. 16 volts/1.2 ohms = 13.3 amps, so assuming the resistive load stays the same, the amperage does go up when going from 12 to 16 volts. Now, add in the fact that a 16 volt system should charge at 18.5 volts, the amperage draw I showed above would be a low estimate.This message has been edited. Last edited by: <DOTracer>,
As a bracket racer I can’t imagine not running an alternator. Now I’m only 12v but have run lots of double races. Not unusual to make 9-13 passes and never charge. One less thing to worry about. Just my opinion though. Now heads up it makes sense to run without it.
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What is the alternator / crank pulley ratio ?? What size wire from alternator to battery ??
5.2" crank pulley, 2.8" alternator pulley, 1.86 to 1 ratio. Raising engine rpm from 1300 rpm idle to say 3500 rpm made zero difference.
Cable from alternator to battery is 4 awg as well as a 4 awg ground cable from the alternator case to the engine block. There is also a 2 awg cable from the battery to the firewall where there is a pass through stud for a ground for the block & cylinder heads.
I would never run my cars without an alternator.
Not running one now but not really any room for one either. Trying to figure it out though. I prefer to run one.
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I know how it works with DC motors, increase voltage 25% you increase amp draw 25%. I don’t go by what they say it draws I go by what it actually draws. They may draw 12 amps on start up but fall back once up to speed. I have repaired close to 400 pumps of various manufacturers, mostly CSR and test them all and they are all real close on amp draw. Test yourself if you don’t believe me.
I also have my Meziere waterpump fused at 15 amps and on 16 volts with alternator and never popped a fuse yet.
XS D1600 XS Battery here with a Mark Payne @ House of Payne Performance 16V Super Mini Alternator here. It is a fantastic setup, love everything about it. At around 1000-1100 idle, I may only get around 17-17.5 volts, but as soon as it gets throttle or if I raise idle a couple hundred I'm at 18 all day long and Grid shows its about 19.2 down track.
1971 Camaro Split Bumper
yea, I'm running a XS D1600 and have a east coast 12 volt alternator laying around... I'll send it in to get upgraded to 16V. Always used it with the 12v system.
I know Mark can do the conversion if you'd like. Either way, I don't think you'll regret having the alternator on the car with the 16V.
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I believe you have it backwards. As voltage goes up Amp draw goes Down.
I also agree with Curtis Reed and always run an alternator although on my dragster it was a real pain to mount one.
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Bucky the windings in a DC motor is a fixed resistance, voltage applied to it doesn’t change the resistance so if you increase the voltage you also increase the amp draw. Amp draw does go up with lower voltage when you start to stall the motor such as dead battery trying to crank over a starter motor.
Now a motor that is designed to do the same work but at a higher applied voltage will have a lower amp draw but it is wired with different size windings and different number of wraps per coil.
in a/c motors it is opposite but in dc as voltage goes up amps go up .i think,when doing the math from ohms law thats what it shows if i did it correctly
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1.036, 6.16@ 224
You are missing the power to run the equipment
Potential output 18.5
18.5v x 65a = 0.28462r
Actual output 16.5
16.5v x 65a = 0.25385r
Difference in resistance
0.28462 - 0.25385 = 0.03077
A x R = V
65a x 0.03077r = 2.00005v
Alternator is putting out full voltage
18.5v potential - work 2.00v = 16.5v recorded voltage on B+ post
Just a note...Resistance is never fixed
Resistance cause heat...Heat increases resistance...Resistance is variable...Just as all the other variables in Ohm's law formula
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