by Wayne Scraba
NHRA Pro Stockers are probably the best battery poster-children of the go-fast crowd. Their batteries are a bigger piece of the performance puzzle than most people think.
Battery Options
Many racecars that are equipped with high-output ignition systems are well suited to deep-cycle batteries (which are designed to withstand repeated deep-discharge and recharge cycles). Although a deep-cycle test is perhaps the toughest measure of battery moxie, many deep-cycle batteries aren't ideal for day-to-day starting, cool weather and so on. In general, then, cars that have an onboard charging system (i.e., alternator) usually don't need this more-expensive deep-cycle design.
For street/strip vehicles, a 16-volt battery is another (albeit relatively recent) option. If you've ever raced your car and progressed deeper into the rounds, the time between runs decreases. That's precisely where the advantages of a 16-volt system enter the equation.
As background, many racing ignition systems require at least 12 volts to produce optimal spark. A typical lead-acid battery cell produces a maximum of 2.1 volts per cell (open-circuit) or 12.6 volts total. Under load, the voltage can rapidly drop to 2.0 per cell (6-cell battery), or 12 volts total. Operating below this voltage level can cause ignition problems such as a high-speed miss. Reduced voltage will also negatively affect the starter's ability to spin the motor, so racers can definitely benefit from additional voltage.
As street-strip cars get more electronically sophisticated, the amp-draw loads increase. This shortens the amount of time it takes for a 12-volt battery to drop to marginal voltage levels; 16 volts provides a 4-volt cushion to the electrical system. Instead of a 12.6-volt full-charge, the 16-volt battery offers 16.8 open-circuit volt (2.1 volts per cell times 8 cells). Even when totally discharged, a 16-volt battery will produce 14 volts (as opposed to a discharged 12-volt battery's 10.5 volts), which still exceeds the minimum recommendation for racing ignition systems. The primary reason for using a 16-volt battery is, of course, to improve the performance of the ignition system. Typically, a 16-volt battery can help to fire massive plug gaps (up to 0.080"). In some cases, this can also lead to increased carburetor jet sizes over a 12-volt baseline. Another claimed benefit is that the hotter spark keeps engines from falling off as much in "bad air."
Compatible Components
> Ignition: Most high-performance systems need at least 12 volts for proper operation and will benefit from 16 volts. The more input voltage to the ignition, the greater the output from the ignition. More spark + more fuel (larger jets, higher fuel pressure) = more power.
> Starter: 16 volts will spin the starter as much as 33% faster than 12 volts.
> Electric Fans will spin 10% to 15% faster with no damage to the fan.
> Electric Water Pumps will spin 10% to 15% faster, resulting in quicker cooling.
> Electric Fuel Pumps will build an additional 4 to 6 pounds of pressure at the pump. Although additional pressure (in most cases) is not required, the extra pressure can be backed down at the regulator if desired.
> Most 12-volt components will operate fine on 16 volts because a 12-volt alternator can generate as much as 15 volts. Some components such as electric transmission brakes, delay boxes, timers and throttle stops, a resistor may be required to step down the voltage. Increasing wire size can eliminate the need for a resistor in some cases. If in doubt, contact the respective electrical/electronic component supplier.
2-Post Vs. 3-Post
For those who want the best of all worlds, 3-post 16V/12V batteries were available. Three posts allow those items whose performance is improved by 16 volts to receive more juice while all other accessories get the traditional 12 volts. The battery manufacturer can supply a 3-wire booster that allows any 12-volt alternator or charger to be used and keeps all eight cells at equal levels of charge.
Possible scenarios and considerations:
> If using a 12-volt alternator, a 3-post battery with a boost box will allow running only the ignition and starter on 16 volts and all other components on 12 volts. With this setup, a 12-volt charger with at least a 20-amp output setting is necessary to juice up the battery.
> If using a 16-volt alternator, consider a 2-post battery with resistorized electronic components. (A 16-volt alternator can produce approximately 20 volts to keep the 16-volt battery charged.) A 16-volt charger will be required to initially charge a 2-post 16V battery.
> For no-alternator racecars, use the 2-post system to avoid a charge imbalance among cells.
> The best (and simplest) system for drag racing is a 2-post battery with a 16-volt charger and no alternator.
Dual Batteries
Dual batteries usually aren't necessary in vehicles that have capable charging systems, but keep in mind the electrical loads placed upon the battery. That said, dual batteries could definitely be a bonus in racecars.
Wiring these batteries in parallel effectively doubles their individual capacity. To do this, route the "hot" starter lead to one battery, then run a line from the (+) post on one battery to the (+) post on the second battery. The second battery should then have its negative post (-) grounded with a cable joining both (-) terminals on the battery.
Use batteries from the same manufacturer and of the same capacity. Only use new batteries and do not mix a new battery with an old battery. (In other words, the batteries should be identical.)
In the end, there's much more to batteries than finding the best deal at the corner auto parts store. Give batteries some extra consideration, especially if you play with your car at the drag strip.
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