| ELECTRICAL SYSTEM Dual Batteries & more |
| Last Update: December 7, 2004 |
| My electrical system has undergone a number of changes over the last few years. The most significant was when I had as many as three batteries and two separate alternators working at the same time. You can read more about that system below. I later removed it, when I installed air conditioning, as one of the alternators was located in place of the A/C compressor. Today, the system includes only two batteries and a single alternator, but includes a few more features. The batteries and electrical systems are controlled and isolated electronically. The system uses an Optima Red Top battery in the stock location. It normally powers all of the truck's stock electrical systems in addition to being the primary power for the starter motor and winch. A second Yellow Top deep cycle battery is located in the bed. It is connected to the Red Top via a 200 continuous duty amp rated relay system that is controlled either automatically when the ignition is switched on or via a manual override switch. The Yellow Top battery is the primary source of power for all other auxiliary systems, such as the driving lights, interior lights, Ham radio, refrigerator and all power outlets. It is wired to power a rear winch, although I currently don't carry one. The long main power lead between the two batteries is protected by a 200 amp fuse at both ends. The Yellow Top battery can also be completely disconnected from all electrical systems via a second 200 continuous duty amp relay. The chief purpose of the system is to provide a back up starter battery in the event that the primary battery fails or drains unexpectedly. In addition, the deep cycle battery is able to be isolated and used to power equipment overnight while camping. Both batteries can be charged at the same time and connected together to provide ample current for winching operations. |
| The front Red Top battery and basic view of the front wiring, including relay that connects the two batteries. It's not the cleanest set up from having to modify it a number of times, but it works and it's reliable. |
| The basic wiring diagram of my current system. It may seem complicated, but that's because it's the result of several modifications from the original triple battery- dual alternator system. |
| The rear Yellow Top deep cycle battery and relay that completely isolates the battery from all power sources via the flip of a switch. Also note the 200 amp fuse. |
| Electrical System Completely Turned Off When turned off and isolated, the volt meters read the current voltage of both batteries, which in this case is fully charged at about 12 indicated volts (actual voltage is about 12.6, but there is a slight drop in the wiring leading to the gauges) The main relay switch, which controls the connection between the two batteries is in the off position. Both batteries are totally separated. The rear battery relay switch is also in the off position. This completely isolates the rear battery from all electrical connections. The purpose of doing this is to prevent drainage from the multiple systems, such as radios, GPS, and battery chargers, which use this battery as the primary source, when they are not in use, but still draw minimal current. Independent, the current draw of each system is nominal, but when combined, they can drain the battery in only a few days. Isolating the battery via this relay is easier than trying to unplug each electrical system when not in use. It is also an added measure of security in the event the hard to reach rear battery were to short out and the fuses didn't trip, the battery could be disconnected with the flip of a switch in the cab. |
| Front relay turned off, rear relay turned off, engine running When both relays are turned off, but the engine is running, the alternator still charges the primary Red Top battery and now indicates 14+ volts in the picture. The two batteries are disconnected from each other, which means the rear Yellow Top is not charging and still indicates 12 volts. In addition, the rear relay is still turned off, which means that no electrical system is connected to the rear Yellow Top battery. In this case, all auxiliary systems are disconnected and things like the GPS, Ham radios and off road lights will not function. However, all factory systems in the truck will function normally. I would only use the system in this mode in the event that there was a major short in some of the auxiliary system wiring and I did not have time to repair and I needed to completely shut down all auxiliary electrical systems, but still be able to drive the truck. If I were to turn on the front relay, but leave the rear relay and rear battery disconnected, all systems in the truck, including auxiliary systems would run off of the front Red Top battery. I would only use this mode in the event that the rear battery itself shorted out and failed or if the alternator failed and I wanted to stored a fully charged second battery for future use. |
| Front relay turned on, rear relay turned on, engine running (normal mode) This is the most common setting. The front relay is set to automatic-ignition. This means the relay turns on the instant the ignition is turned on and connects the two batteries with the driver having to do nothing. In addition, both batteries are automatically disconnected when the ignition is turned off, which allows for the rear Yellow Top battery to be isolated as a back up battery in event the primary battery were to drain. With the engine running, both batteries are equally charged at 14+ volts. The entire electrical system is now interconnected and all systems, including factory and electrical are powered off of both batteries as if it was one larger battery. |
| Front relay turned to override, rear relay turned on, engine off This is the back up mode for the front relay. Instead of turning on via the ignition, the front relay has a manual override which allows the two batteries to be connected while the engine is running, in the event the ignition connection fails or while the engine is shut off. The most common use would be when the engine is off, but the combined current of both batteries is needed. For example, if the primary battery, which starts the truck, were to die, or if the engine died, but the winch was still going to be used. When connected, both batteries will reach the same voltage, in this case 12 volts, which also indicates the engine is turned off. If one battery were dead, when connected, the voltage would average out. While it would be significantly less then 12 volts, it should be enough to start the truck. |
| Front relay turned off, rear relay turned on, engine off This final mode is used when camping and battery power is needed, but I don't want to affect the primary starter battery. The front Relay is turned off, which isolates the primary Red Top battery from all auxiliary electrical systems that I might use when camping, such interior lights, power outlets, GPS, radios, etc. If the front relay switch is set to auto, the relay automatically turns off when the ignition is turned off. The rear Yellow Top battery relay is turned on, to connect the Yellow Top to the auxiliary systems. In the event that I were to run the yellow top battery down over night it would have absolutely no affect on the primary starter battery. Once the truck is fired up, the alternator would begin charging the dead battery. |
| This system is still being tested and is a little complicated, but has built in bypasses, should the electrical relays fail. Right now the current weak link is the alternator. I've traded a combined output of 210 amps from two alternators, to the output of only 60 amps from a single stock unit. I plan to upgrade the single alternator to a more powerful one in the very near future. While I do miss the versatility, power output and uniqueness of the dual alternator system I had before, I couldn't be happier to finally have air conditioning for those very hot summer trips into the desert. This new system should work perfectly fine. The only other addition, besides the upgraded alternator that I might make is the addition of a solar panel, which would allow me to run the refrigerator all day long, even when the truck is not running, without worry of draining either battery. The End Go to my Homepage or check out my old system as outlined below. |
| My old triple battery, dual alternator electrical system. This is a write up about my old system. I'm leaving this up on the site for informational purposes. |
| My original electrical system design consisted of two seperate alternators and three Optima batteries. The electrics were split into two seperate systems. A stock main system and an auxiliary system. Both systems run completely independent of each other, but can be connected with a flip of a switch in an emergency. The main system, otherwise known as the stock system, powers only the factory portion of the truck, i.e., the starter motor, headlights, heater, ignition, etc. All accessories, including the off road lights and both the front and rear winches, run off of the auxiliary system. The only major change today is that the auxilery system which used to have two batteries, now only has one. The two seperate systems allows for the winches to be run without draining the ignition system and starter battery thus giving added security. It also allows for an abundence of reserve electrical capacity that can be used while camping and for emergencies. The main system consists of the stock 60 amp alternator and one Red Top Optima battery. The auxiliary system consists of one 160 amp GM style Delco-Remy alternator (located in place of an air conditioning compressor) and one Yellow Top Optima deep cycle battery located in the bed. I used to have incorporated into the system is a marine type battery switch which allows the three batteries to be hooked together in various combinations depending on the situation or emergency. Today the two systems are seperated via a 250 amp solenoid. They would only be connected in the event that the starter battery needed a jump start or if I was doing an extended winching operation and needed all the batteries and alternators. 200 amp slow burn fuses are used to protect the long potentially dangerious battery wiring. |
| Wiring Diagram. Click on image or HERE for a larger view. |
| The diagram on the right is of the old set up. I'll a diagram of the new system up in the future. |
| Over all view of the engine compartment, showing the main battery on the left side. This is how it looks today after removing one of the aux. batteries. See below for the old set up. |
| Although difficult to see, this is a view of the main stock 60 amp alternator. This unit has been rebuilt but is otherwise left stock for reliability. |
| The auxiliary alternator: This is a GM style internally regulated Delco-Remy alternator. Stock output is about 100 amps. This unit has been beefed up to make a maximum 160 amps. The alternator is mounted where the stock air conditioning compressor would have gone and uses the A/C compressor crankshaft pulley. The mount is a Honda Civic alternator mount, bolted to a flat piece of stainless steel which is bolted to the A/C compressor bolt hole locations. The upper mount is custom made...see next picture. |
| This is a view of the upper bracket of the auxiliary alternator. The upper bracket is custom made from a Honda Civic alternator bracket and bolted to the engine head. Belt tightening range is a bit limited but it works. Special Thanks to my Dad, for building both the upper and lower brackets for this alternator |
| Click on logo for link to Optima's website |
| Deep Cycle Battery |
| Starter Battery |
| The Optimas are great batteries. I'll let Optima do the selling though. Visit their website via the links above if your interested. One thing of special note though. The older Optimas, such as the ones I have, are mysteriously rated higher than the current Optimas. For example, the old yellow top Deep Cycle batteries are rated at 750 cca and 65 A/h, whereas the new Optimas are rated at 550 or 650 cca (depending on which literature your read) and 55 A/h. I inquired to Optima about the change. They told me they simply rate them more conservatively due to new ownership (Johnson Controls). One distributor told me, he thought that the old Optimas used virgin lead, while newer Optimas use recycled lead. It's still a mystery, but regardless, they are wonderful batteries and I would highly recommend them. |
| The new system is much simplier than the old system (see below to see the details of the old system) yet retains many of the advantages of the old system. By using two alternators, I can completely seperate the stock electrical system and isolate it from all of the auxilery systems, thus dramaticly improving reliability. Should one of the systems fail, the other can act as a back up. And the auxilery system, particulary the winch, would not interfere with the stock system. A great example of how this can be a problem is a little experience I had in the old days with just one alternator and one battery. It was a cold snowy evening and I was running my windshield wipers, heater and headlights. I also had to winch out of a snow bank far up a remoted snowed in road. My stock electrical system was so overwhelmed that it almost died. Had it died, the engine would have died with it and I would have been stranded. With this set up, I can winch all day long without it ever affecting my engine, headlights, heater, etc. Should the winch battery and alternator become overwhelmed and/or fail, I would still have a working engine. In the most diar emergency, both systems can be connected to provide two batteries and a total of 210 amps of charging power to run the winch. |
| Over all view of the engine compartment, showing the main battery (right side) and one of the auxiliary batteries (left side). |
| The old set up. Today the stock air filter resides here. Main battery. Charged by the stock alternator, this battery powers the engine, starter motor, and main truck fuse box. The main fuse box powers all of the truck's stock accessories, such as ignition, headlights, heater, etc. |
| Auxiliary battery # 1 -- and main switch. (located in engine compartment) This is one of two auxiliary batteries. This battery powers the front winch and off road lights among other accessories. Is augmented by a 2nd auxiliary battery (behind cab in bed) when the two are connected. It is charged by a 160 amp auxilery alternator. |
| Auxiliary battery # 2 (located behind cab in cargo bed) This is one of two auxiliary batteries. This battery powers the rear winch and air compressor among other accessories. It is augmented by the 1st auxiliary battery when connected. It is charged by the 160 auxilery alternator, but can be disconnected via the main switch from 1st aux. battery and aux. alternator. It also supplies power to a cooler located in the canopy and to running camping equipment. |
| This marine type battery switch connects all three batteries or a variety of combinations of the three. |
| The main purpose of this battery switch is to allow for the easy connection of the three batteries or a combination of the three for a specific purpose. In an emergency for example, when the main battery is dead and the truck is unable to start, one or both of the auxiliary batteries can be switched to the main battery, thus allowing the truck to start. In addition, under normal circumstances the front and rear auxiliary batteries are connected via this switch and run in series. They are then both charged by the 160 amp alternator via auxilery battery # 1. However, if desired, auxiliary battery # 2 (behind cab in the cargo bed) can be disconnected from auxiliary battery # 1 and the alternator. This would allow auxiliary battery # 2 to be used to be used overnight for camp lighting or running an electric cooler while at camp, but still leave two fully charged batteries available for use in the morning. It also can provide power for an emgergency ham radio repeater, while the truck is unattended. |
| The main battery switching position and corrosponding results: |
| SWITCH IN "OFF" POSITION All three batteries are disconnected from each other. Main battery and Aux battery # 1 are charged by their respective alternators. Aux. battery # 2 is stand alone and not being charged by any alternator. |
| SWITCH IN "# 1" POSITION Main battery and Aux. Battery # 1 are connected as are both alternators. This position is only to be used when emergency jump starting the main battery. Upon starting engine, switch is be turned to a different position, to prevent voltage conflict between the two alternators. |
| SWITCH IN "ALL" POSITION All three batteries and both alternators are connected. This position could also be used to jump start the main battery by connecting both aux. batteries to main battery to start the truck. Also if one of the two alternators were to malfuction, switching to this position would allow all of the truck accessories and all three batteries to run off of the remaining alternator. |
| SWITCH IN "# 2" POSITION This is the default setting. The main battery system and the auxiliary battery system are disconnected from each other. Aux. batteries # 1 and # 2 are connected to each other in series and are charge via the 160 amp auxiliary alternator. When winching either from the front or rear, both auxiliary battieries are used. |
| There are three main disadvantages to this system. Weight, complication and increased danger of fire or electrical short. The increase in weight comes from the three very heavy batteries, each of which weigh approximately 40 lbs. The three batteries are the rough equivilent of one passenger in weight. This system originally had only two batteries, utilizing one main battery and one auxiliary battery. The reason for going with two auxiliary batteries is further explained in the "advantages" section below. This system is complicated, but not as much as it could be. It is more complicated than a stock system, which is why this can be a disadvantage, but it is far less complicated than many pre-designed dual batteries systems. I explain further in the "advantages" section. There's no denying the increase in fire danger. Due the extremely high amperage that some of the battery cables see, there is a limited fire danger. Most of the high amperage battery wiring are protected with 200 amp fuses. This limits the amount of current allowed to flow through the protected wiring. The system has not been fully tested, so I'm not sure if the 200 amp fuses are too small. Since the front winch pulls 460 amps, that wiring cannot be fused. If a dead battery was connected to the auxilery batteries, I'm not sure if the fuses would blow due the very high current passing from the good battery to the bad battery. Because the rear winch uses the smaller 1.7 h.p. motor, I'm confident that it's fused winch wiring should work. I'll report more as testing is completed. |
| UPDATE In running this system for well over a year and a half, I've no problems at all. The slow burn fuses help negate any fire danger and the system is actually quite simple, compared to some electronicly control systems. The only problem I had, so far, was the alternator bracket vibrated itself loose on a long trip to Montana and I almost lost the auxilery alternator. That has since been fixed. |
| This system provides numerious advantages, not the least of which is security in knowing that there is a back-up or triple back up to the main battery should it go dead. This system is perfect for back country travel in very remote areas. This system provides a huge source of electrical power for front and rear winching, since winching requires enormous electrical current. The further the winch is from the battery the less effecient the winch and the electrical system will be. In it's original configuration, the rear winch was hooked to the single auxiliary battery in the engine compartment and had to travel 18 feet before reaching the rear winch. This length of wire caused the rear 5000 lb winch to lose much of it's capacity and stall out long before it should have. With the rear winch now hooked up to a source of electrical power about 6 feet away, it's much more effecient. The front winch has always had it's main source of power close by. The auxilery battery # 1 it uses has less than 2 feet of wiring between it and the front winch. However, the single 750 cca battery (now rated 550 cca by Optima) is barely adequate to power the 4.8 h.p. winch motor, even with the 160 amp alternator. Now, when winching with either the front or rear winch, both auxiliary batteries can be connected giving an effective cold cranking capacity of 1500 cca. (1100 cca with the new Optima rating system) This is a far superior winching system that should allow for long duration trouble free winching. The limiting factor now, is overheating the winch motor. With two auxiliary batteries, one or both can be used for electrical power at remote camp sites at night. With a fully charged starter battery disconnected from the auxiliary batteries, I can camp worry free knowing that you'll be able to start the truck in the morning. For extra security, only one of the auxiliary batteries can be used and drained overnight at camp while the starter battery and one emergency auxiliary battery remain charged and ready to go in the morning. Since both auxiliary batteries are of the deep cycle type, they can be fully drained and recharged much more often than the starter battery. They are perfect as winch batteries or as an overnight power source for a camp light, radio, electric cooler or any other 12 volt electrical devise. This system is much less complicated than it could be. Many dual battery systems use solenoids or isolators. This system simply uses one mechanical switch. The auxilery alternator is a very simple unit. Since the systems are completely seperate, they can work independently or augment each other if needed. The only likely parts to fail are the alternators themselves. |And with two available units, there is always a back up available. |
| UPDATE This system has proven very successfull, but as mentioned in the beginning, is kind of overkill. For most people, 2 alternators and 3 batteries are not necessary. The advantages of this type of system are where winching is done on a regular basis and trips are taken into extremely remote areas. I rarely use the winches. Usually only during the snow season. But I do drive on very long trips into remote areas, so the system has proven it's worth here. Having two alternators can allow the use of one as a back up. When my auxilery alternator almost fell off, on a very long trip, I had to cut the belt and temporarily remove it. With my stock alternator still working, I was able to charge all three batteries with that alternator and continue to operate all of my electrical systems. The same could have been said, had the stock alternator failed. However, for most people, I think that a simple single alternator, dual battery system would work perfectly fine. I recommend using a high output alternator in place of the fairly weak stock 60 amp unit and using 2, very high quality batteries, such as the Optimas. An Isolator, in between the batteries will ensure that you always have one good battery to start the truck, should the main battery fail. A switch could be hooked between the batteries, should it become necessary to use both for winching. |
| If you have any questions, don't hesitate to email me. |
Wiring Diagram
Batteries and Alternators
Batteries Specifications
All of the information below pertains to the old system.
Disadvantages
Advantages
Conclusion
click here for Specs.
click here for Specs.
| This rear battery set up was slightly changed, since a canopy was added. The battery is now in the same general location, inside a battery box. |
Conclusion
