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Battery-Saving Devices

Written by Keith Mandic

Keith Mandic and Mike Malec are both product and service specialists with Lund Industries. Lund Industries is a major emergency vehicle upfitter and aftermarket parts manufacturer in the Chicagoland area. Lund Industries is currently celebrating 27 years in the business of public safety equipment design, installation and distribution, and parts fabrication.

Lund Industries products include Control-Com consoles and mounting systems, lights and flashers, sirens and speakers, and other emergency vehicles products such as battery- saving devices. Lund Industries is a distributor for some of the devices reviewed in this article. For a complete list of products and services, please see their Web site at www.lund-industries.com.

Ed. Note: On a properly upfitted police vehicle, the battery will never be drained dead. Importantly, modern batteries cannot be deep cycled (drained dead) and then fully recover by being charged like the old lead-acid batteries. Deep cycling quickly ruins today’s batteries. Many die in as few as a dozen complete drains. Some lose up to 50 percent of their cranking capacity in as little as two complete discharges. If it goes dead twice, it is half the battery it once was.

Power drains take two forms. One is the amp draw from emergency and communications equipment exceeding the output of the alternator while the vehicle is running. Even with 200 amp (and upcoming 220 amp) alternators, or alternators with high-idle software, it is entirely possible to overtax the alternator.

The upfitter’s manual available from all three automakers indicates how much current the basic (non-upfitted) vehicle takes to operate, and how much current various accessories (like a rear window defroster) take to operate. With all police vehicles, under some circumstances, there is very little alternator output to spare.

The manufacturer of each upfitted aftermarket device (radio, lightbar, e-printer) can provide the amp draw for its devices. The total demand from the operation of these aftermarket devices cannot exceed what amps are still available after the needs of the basic vehicle.

If the amp demand exceeds the amp supply, the battery will start to drain, even though the engine is running. The battery will eventually be drained to the point that the vehicle will not be able to start. The solution is either to reduce the amp draw (install or use less battery-draining devices) or to have these devices selectively, automatically shut off.

The second source of power loss is parasitic amp draw from all of the aftermarket accessories installed during upfit. MDT computers, in-car cameras and other electronic gear can continue to pull small amounts of power even if shut “off.” These milliamp, insignificant amp draws will drain a battery dead just as sure as the 75 amp halogen lightbar.

Many solutions to parasitic power drain exist. Parasitic drain is very different from the 140 amp power draw from operating emergency gear exceeding the 120 amps at idle produced by the alternator when the car is running. This can, indeed, deep cycle and kill a battery. That is why a proper amp load calculation must be done.

Instead, parasitic draw comes from dozens of milliamp draws from the car’s own computers and control modules, as well as aftermarket laptop computers, in-car video systems and communication gear. In these cases, the constant, round-the-clock milliamp draws all add up, and the result is a dead battery.

The solution is a slow, methodical, painstaking look at everything added to the vehicle that draws power. Especially problematic are some modern, digital in-car cameras that actually run all the time. In some cases, these can be reprogrammed to run only when the car is operating, or there are other similar power-saving techniques.

Other approaches also exist, depending on the specific car, gear and problem. These include installing timers, wired to the ignition, that cut the power a pre-set time after the car is turned off. Battery voltage sensors do the same thing—they monitor the remaining voltage in the battery as it slowly drains and shut off the power draw when the battery has just enough voltage to start the car. Park shut-off modules are a similar solution.

The following is a complete roundup of timers, voltage sensors and combination timers-sensors. Each company makes a wide variety of such devices. We picked just one representative device per company, as close to apples-to-apples as possible. We took into consideration both cost and simplicity. In most cases, we simply picked what was the most popular choice for police vehicles, as opposed to other applications like fire apparatus. Please visit the Web site for each company to see what other devices are available, such as more features, fewer features, different connection options, etc.

As a general rule, screw-on terminal connections are more durable and reliable than push-on terminal connections. Push-on terminals may vibrate loose (or accidentally be pulled off) and may be more subject to corrosion.

The final tip is don’t blame the upfitter, and don’t blame the battery-saving device for an already compromised battery. The car sat backed into the chain-link fence for three months before the upfit began. The battery was drained completely dead, of course, even though every automaker has simple and effective instructions for long-term storage. The battery must be in good shape at the start of the upfit.

The biggest mistake made with battery- saving devices is to not check the battery and charging system first to make sure they are OK and everything is in spec. If a battery is not holding a charge on its own or one particular car is always going dead, conduct a little troubleshooting first before installing a device to make sure there isn’t an underlying cause of the problem. Don’t treat the symptoms, treat the cause.

AC/DC Industries
Model: Delay Timer MZL-10SW
Device type: Timeout timer, low and high voltage disconnect
Size: 4” x 2” x 1.5”
Load capacity: 30 amps max
Low voltage cutoff: 10.5 volts DC
High voltage cutoff: 17 volts DC
Time delay: User settable from 15 seconds to 8 hours
Standby current draw: 6mA
MSRP: $81.35
Warranty: 1 year limited warranty

The MZL-10SW timer has a voltage sensing turn-on lead that must be connected to the ignition switch to start its timing cycle. A single 6-inch length of 10 gauge wire extends from the potted chassis to be connected to the battery with a user-supplied fuse with a maximum draw of 30 amps. Three exposed 1/4-inch male spade terminals provide timer output for devices. It is up to the installer to provide fuse protection.

Time delay is made using the top mounted DIP switches giving eight delay settings from 15 minutes to eight hours. A red LED indicator next to the switches flashes when the unit goes into its countdown cycle. There is also a pushbutton override next to the DIP switches that will turn the timer on temporarily without using the ignition switch.

Although the chassis box is potted to protect the electronics inside it, the MZL-10SW should still be mounted in a protected environment as the output terminals are exposed along with the top mounted switches. Because wire leads are used instead of terminal blocks, care must be taken to make good crimp connections when attaching or extending the wire.

The same applies for the output terminals. The disconnect terminals should be clean and tight with periodic inspections to make sure they haven’t loosened up due to vibration. A light coating of dielectric grease on the terminals will help keep corrosion to a minimum.

Remember, the jumper wires extend inside the potting compound on the chassis. When you remove the box at changeover time, don’t cut the leads too short! If you do and there isn’t enough wire left to splice to, there’s no way to repair them and the unit will have to be replaced.

BLI International
Model: PriorityStart! PSI-12V-PROMAX
Device type: Low voltage battery disconnect
Size: 4.125” x 3.0” x 1.25”
Load capacity: 250 amps continuous
Standby current draw: 12mA connected, 9mA disconnected
MSRP: $108.95
Warranty: 12 month limited warranty

The PriorityStart! 12-Volt ProMax is a battery rundown protection device wired into the main battery positive cable in a 12-volt negative ground electrical system. It monitors at-rest battery voltage, and if it should drop to 11.7 volts or less for one full minute, it will open the circuit and disconnect the battery from the vehicle. An LED on the front of the PriorityStart! housing shows green if the unit is connected and red if the unit has been activated and disconnected from the battery.

PriorityStart! is furnished with battery cable adapters for top post and side terminal batteries; a 12-inch long, 6 gauge main input cable; a black, 18 gauge ground wire; and a black “rubber band” to hold the case against the battery. The basic installation requires removing the vehicle battery cables from their posts, cleaning the battery cables and posts to ensure good electrical contact, and reconnecting the cables—negative first with the black PriorityStart! lead attached to it and the PriorityStart! unit, then the red positive cable.

Anything that draws power should be run through the PriorityStart! device. The last step is to slide the unit under the band holding it to the battery case. To test the unit, first make sure the key is out of the ignition; turn on the headlights and let them take battery voltage down to the disconnect threshold. While you’re doing this, it’s a good idea to monitor the system voltage with a digital volt meter just to double check the installation and operation.

Once the unit trips, wait a full minute; then reconnect the unit by turning on another load in the vehicle such as the spotlight, stepping on the brake pedal or turning on anything that will draw 2 millivolts (0.2mV) or more. It’s the sudden load transient that the PriorityStart! needs to see to reset itself.

If there is no space available at the battery, the input cables can be replaced with longer customer-supplied pieces and the unit firmly attached to the fender liner or other secure area of the vehicle.

The PriorityStart! units are only as good as the battery and electrical system they are connected to. Many times they are improperly used in an attempt to fix a charging system or battery that won’t hold enough of a charge to start a car after it’s been sitting for a few days. They won’t protect against a dead battery if the car is left unused in long term storage.

Always check the battery and charging systems first to make sure they are in good working order before installing these units, as they are designed to catch lights left on or a door left open (fairly large draw) after the engine is shut off and the key removed. If a battery slowly discharges on its own, the device may catch the voltage drop and open the circuit, but the battery has discharged enough internally that it won’t crank the engine.

There is a very good nine-page troubleshooting guide that can be downloaded from the PriorityStart! Web site explaining in detail installation, problem troubleshooting and warranty procedures.

Cole Hersee Co.
Model: FlexMod 48541-01 Voltage Sensing Relay & Timer
Device type: Battery monitor with timeout timer, low and high voltage disconnect
Size: 4.0” x 3.0” x 1.0” without wire harness
Load capacity: 10 amps max
Low voltage cutoff: 7 volts DC
High voltage cutoff: 18 volts DC
Time delay: Factory preset 15 minutes
Standby current draw: 2mA
MSRP: $74.67
Warranty: 1-year basic warranty

The new FlexMod device from Cole Hersee is said to be weatherproof, dust proof and vibration proof; therefore underhood mounting should not be a problem. Wires are connected to the main unit with an 8-pin Amphenol weatherproof connector with 5-inch jumper wires extending from it. Make sure any wire splices are correctly done if it is to be mounted under the hood.

This makes swapping out units very easy if one should fail. However, make sure you take the pigtail jumper along when moving the box from car to car at changeover time. Otherwise, you will have to order a replacement harness because there is no other way to connect it. Importantly, the Voltage Sensing Relay and Timer is sold separately from the Mating Connector (Harness) Kit. You need both.

Shipped with the jumper pack are additional jumper wires, blanking pins to insert into unused positions in the connector body to maintain the weather seal, and a locking wedge to keep everything locked in place once it’s assembled. The jumper can be configured for a variety of applications, so it’s left to the installer to complete it as needed.

The FlexMod is rated at 10 amps directly but will easily operate customer-supplied auxiliary high current relays if more capacity is required. Switching is done with solid state devices, not relays, for improved reliability and smaller packaging. Shutdown time is factory programmed for 15 minutes. The familiar DIP switches from other timers are not present.

To change the shutdown time or other features, the unit must be linked with a Field Programming System connected to a PC. This is an interface module connected to a Windows PC running the Cole Hersee proprietary software. The concept is similar to that used by other manufacturers to program custom light bar and siren functions. The Electronic Field Programming System controls low and high voltage cutoff points, disconnect delay time, connect delay time and length of alarm time output. These functions are based on preliminary information and are subject to change.

An interesting feature of the FlexMod system is the remote mount alarm indicator. Because the box can be mounted underhood, the unit does not have any warning indicator mounted on it like the other devices have to let you know, for instance, it’s in the countdown mode. Instead, FlexMod has an output wire to connect to your remote-mounted LED indicator or piezo buzzer device. This wire can handle up to 200mA which is enough current to control a relay coil if necessary. The warning devices themselves are not included so plan ahead when installing one of these modules.

Copeland Engineering LLC
Model: Power Tamer VS Delay Timer
Device type: Timeout timer, low and high voltage disconnect
Size: 3.9375” x 3.0” (including mounting ears) x 1.0”
Load capacity: 30 amps max
Low voltage cutoff: 10.5 volts DC
High voltage cutoff: 16.5 volts DC
Time delay: 15 min to 16 hours
Standby current draw: 3mA
MSRP: $93.66
Warranty: 2 year exchange

Copeland’s Power Tamer is the only product with its circuitry potted in a metal housing. Long, 15-inch jumper wires extend from the top of the box for power input and output, ground and ignition control. A nice touch is the weather-resistant fuse holder with installed 25 amp ATO fuse that’s factory installed in the power input wire. The yellow ignition control and red output feed are stamped with the wire function, so there is no questioning their function.

There is no override switch to turn the output power on once the unit times out. The delay time is set with the traditional DIP switches, which are on the bottom of the case, following a time setting chart in the installation instructions. After setting the time, a label provided in the parts pack with the mounting screws must be put over the DIP switch opening to protect them from contamination. Failure to cover the switches will void the warranty. Two LEDs next to the wires monitor the power-in and power- out wires.

Power Tamer VS can be wired using only the power-in and power-out leads. In this configuration, the unit will turn on power when the input wire sees 13.6 volts. This may take some time, especially when the battery has to recover from high cranking loads (diesel engines).

It is recommended that emergency and high draw vehicles be wired with the yellow ignition wire connected. This gives an instant turn-on signal to the timer regardless of voltage. As with other devices, when battery voltage drops below 10.5 volts for 15 seconds, the output will turn off. High voltage disconnect happens immediately when voltage exceeds 16.5 volts.

This timer is a departure from other devices because it uses a solid state field effect transistor (FET) for output switching instead of relays for improved reliability. The metal housing is used for reliability as well as heat sinking for the switching transistors when they operate at near capacity.

D&R Electronics Co., Ltd.
Model: Watchdog-B battery monitor with timer
Device type: Timeout timer, low and high voltage disconnect
Size: 4.375” x 2.5” x 1.375”
Load capacity: 60 amps max
Low voltage cutoff: 11.5 volts DC
High voltage cutoff: 18 volts DC
Time delay: 2 min to 13 hours
Standby current draw: 8mA
MSRP: $95.00
Warranty: 1 year limited warranty

D&R Electronics Watchdog Timer, as with other timers, is not waterproof, so underhood or exposed installation is not recommended. However, it should be mounted as close to the battery as practical because there is a voltage sense wire that must be attached directly to the battery, and voltage drop across long wire runs should be avoided.

Aftermarket mounting of the unit wiring is straightforward with a main power feed run to the battery positive terminal; a ground lead to the vehicle chassis; a lead going to the vehicle ignition switch; and a second, separate, smaller 18 gauge lead going to the battery positive terminal. Input and output terminals are 1/4-20 studs extending from the potted chassis. No fuses or wires are furnished with the unit.

Turn-off time delay is set with exposed DIP switches using a setting chart in the installation instructions. The delay can be adjusted from 2 minutes up to 13 hours. A red LED indicator next to the switches blinks or stays solid to provide status of the Watchdog. A large red momentary push button switch can be pressed to reset the timer at any part of its operation.

If battery voltage is between 13 and 18 volts, as sensed on the 18 gauge wire going to the battery positive terminal, the Watchdog will be “on,” supplying power to the devices connected to its output even if the ignition is turned off. With the ignition off, as soon as battery voltage drops below 13 the unit goes into its countdown mode and will eventually turn off (its STANDBY mode).

If battery voltage goes above 13 volts, such as by charging the battery, even with the ignition off, the Watchdog will stop timing out and turn back on. This is why it’s important to keep the unit as close as possible to the battery so there is minimum voltage drop on the battery sense input.

Havis Inc.
Model: ChargeGuard CG-X
Device type: Timeout timer, low and high voltage disconnect, surge protector, reverse polarity protector
Size: 3.8” x 3.7” x 1.5”
Load capacity: 30 amps max
Low voltage cutoff: 11 volts DC
High voltage cutoff: 18 volts DC
Time delay: User settable from 5 seconds to infinity
Standby current draw: 5mA
MSRP: $90.00
Warranty: 3 year limited warranty

During the past several years, ChargeGuard Inc., now a part of Havis Inc., has released several innovative models onto the market. The latest model, CG-X, is small enough to mount on a sedan trunk or interior, under the dash, or inside a radio console. This unit is not waterproof, and wire connectors are exposed; therefore, underhood mounting is not recommended.

The unit handles a maximum of 30 amps and should be wired directly to the vehicle battery positive post using an installer-supplied fuse and fuse holder of suitable rating for the anticipated electrical load. If multiple devices are connected to its output, each item can be fused individually, again with an installer-furnished fuse and holder. Wires are run to screw post lugs on the outside of the ChargeGuard.

Time delay setting DIP switches turn on the sense mode selector. There is also a 15-minute override switch which is easily accessible under a protective rubber flap on the face of the box. Delay time has eight settings available with the switch setting guide on a decal on the bottom of the unit as well as the instruction sheet.

Also, a 15-minute override button allows the timer to be bypassed if it has timed out. This allows a two-way radio, for instance, to be used temporarily without starting the car. It also automatically protects attached devices against low and high battery voltage by shutting off if any of those conditions occur. When this happens, a diagnostic LED on the face of the box blinks to tell of its status and condition.

In the simplest hookup mode, only three wires are connected: power-in, power-out and ground. ChargeGuard responds to the presence and absence of AC ripple from the car alternator to tell it when the engine is running and when it’s been shut off. This signals the timeout timer of when it can start counting down. There is also a Battery Sense mode that does the same thing but looks for the rise and fall of DC voltage at the battery.

For a more positive control, a fourth wire is added. This runs from the ignition terminal to an ignition-controlled circuit on the vehicle. Presence or absence of 12 volts on this wire will trigger the timer. Usually, the simplest hookup works quite well followed by the ignition control hookup. This device has been refined over the years and is used in many situations, not just vehicles. As new applications arise, the model has been refined to meet those needs.

Lind Electronics
Model: LPT1230-052 Shut Down Timer
Device type: Timeout timer, low and high voltage disconnect, reverse polarity protector
Size: 4.3” x 3.8” x 1.2”
Load capacity: 30 amps max
Low voltage cutoff: 10.5 volts DC
High voltage cutoff: 18.0 volts DC
Time delay: 5 seconds to 4 hours
Standby current draw: 18mA
MSRP: $79.95
Warranty: 3 year limited warranty

T­his unit is a low profile version of other timers offered by Lind Electronics. As with other units, this one is not waterproof and has exposed screw terminals, so interior or trunk mounting is recommended. The 30 amp maximum input should be run directly to the battery and protected with an installer-supplied fuse.

A wire gauge chart in the instructions tells you what gauge wire is recommended based on expected equipment current draw and wire length. The two outputs are rated at 15 amps each, and any device connected to the output should have its own circuit with fuse protection.

Setting and checking the time delay is easy as all controls are out in the open. A potentiometer on the face of the unit is rotated with a small screwdriver to the desired time, and you are done. To speed up checking the delay timeout, a test switch speeds up the timer by 100. For example, a delay of 2 hours (7,200 seconds) will time out in 72 seconds.

The green “on” timing indicator normally blinks at a 2-second rate during normal countdown and will switch to a rapid blink during the fast test. An override button will provide 12 minutes of run time after the unit has timed out or shut off due to low battery voltage. This timer also protects devices against low and high battery voltage conditions by shutting off the outputs if those conditions happen.

The Lind Timer has two hookup methods. The simplest is power in, power out and ground. Using this one, the timer contacts close when battery voltage exceeds 13.5 volts DC when the alternator is charging the battery. Shut down timing starts when battery voltage drops below 13 volts DC, and the alternator stops charging. An optional ignition switch controlled wire can be run to the IGN terminal for a more positive control or for those systems where battery voltage does not exceed 13.5 volts.

Smart Energy Solutions
Model: Battery Brain BB412S Gold w/ pushbutton
Device type: Low voltage battery disconnect
Size: 1.625” x 2.25” x 2.5” without battery post adapters
Load capacity: 250 amps continuous
Standby current draw: 10mA
MSRP: $79.95
Warranty: 2 year limited warranty

Smart Energy Solutions offers the Battery Brain in a number of configurations and current ratings. We chose the BB412S with dash-mounted pushbutton reset switch because it lends itself to patrol car installation. The controller has to be installed directly to the battery positive post with the battery cable, then going to the output terminal of the box. A ground wire is then run to the negative terminal. The reset pushbutton switch and an override wire have to be run inside the car.

Smart Energy Solutions ships straight, angled and side post adapters with each unit to help with installation, but there may be situations where space is so limited that the Battery Brain has to be remote-mounted next to the battery. In those instances, you have to source a battery cable of appropriate length and bolt the Battery Brain to a flat surface next to the battery connecting it to the positive post with the cable.

The Battery Brain constantly monitors the system voltage and will disconnect the main cable if it should drop below 12.1 volts for a specific period. A heavy duty contactor inside the main box driven by a solid state circuit alongside it takes care of making and breaking the circuit.

The device can be bypassed (effectively connecting the battery cable directly to the battery) by unscrewing the yellow cap on top and rotating the button underneath to the “off” position. If it should sense low voltage and trip “off,” this is also the way to reconnect the battery. Unscrew the cap and simply push down on the button.

A sense wire (provided) should be run to the fuse block and tapped to a circuit that is hot only in “run” to keep the Battery Brain from breaking the circuit when the engine is running but the battery is experiencing a very heavy load that drags system voltage below the cutoff threshold.

The pushbutton switch connected to the Battery Brain should be dash-mounted convenient to the driver. It has two functions. If the unit is tripped, press and hold it down for 4 seconds to reset the Battery Brain. If the box hasn’t tripped but the car is going to sit for a while, pressing and holding the button for 4 seconds will “trip” the Battery Brain, thus disconnecting the battery from the car and keeping it from going dead from parasitic draw while it’s sitting. Remember though when doing this, anything with a volatile memory (radio presets, clocks, etc.) will have to be reset.

Published in Police Fleet Manager, Jan/Feb 2011

Rating : 8.2


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Related Companies

AC/DC IndustriesBLI InternationalCole Hersee Co.Copeland Engineering LLCD and R Electronics LtdHavis, Inc.Lind ElectronicsLund IndustriesSmart Energy Solutions

Related Products

AC/DC Industries Delay Timer MZL-10SWBattery-Saving DevicesBLI International PriorityStart! PSI-12V-PROMAXHavis Inc. ChargeGuard CG-XLind Electronics LPT1230-052 Shut Down TimerUpfitting

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