In Merzouga we stayed at Camping La Petit Princess. It was definitely a laundry day, and they provided a machine free of charge. We loaded the washing machine twice and Celine did quite a bit of hand washing. I went to maintaining, cleaning and repairing a few things on the truck. I had opened the toolbox the evening before to get the necessary tools to remove the jack and spare tire when we were getting un-stuck from the sand. In the process I had shoveled a huge load of sand right into the box, and that needed to be cleaned out.
More importantly the spotlights on the truck were not operating (front and right side) so I made that my priority. Armed with a multimeter I began the troubleshooting process. When I flipped the switch each light would strobe one time and then go out. All the floodlights worked, but no the spots. I initially suspected that the spots required more amperage and that maybe there was a lack of power reaching them. The winch, inverter, refrigerator, and exterior lights are all connected to the third battery that rests behind the driver’s side rear passenger seat. I had recently used the inverter to charge a few camera batteries and my toothbrush. The inverter, at 300 watts, drains the battery considerably. In fact, I had drained the battery until it was flat. While alternators do charge batteries they are not designed to recharge batteries that get discharged over and over. They were really designed to top-off starter batteries and to keep steady power running to your vehicle electronics while driving. The output of the alternator, while it has a rating, is actually tied to the vehicle rpms. To fully recharge a discharged deep cycle battery could take 8-10 hours of driving at 2500 rpms. Our alternator had done a surprisingly good job of dealing with the battery, but it wasn’t quite topped off. I tried unplugging everything and running the engine for a while, then pressing the manual override on the battery system, which connected the two batteries under the hood to the third one. That should have provided plenty of power to run any sort of lighting. I tried the lights again and received the same results. Now I needed to try and isolate the source of the problem. Is the issue, battery, battery wiring, wiring to the fuses, the fuses, wiring from the fuses to the connector on the roof, the connector, the wiring from the connector to the light, the light itself, or the ground for the light? You can approach the process from different ends, either from the source of power, or from the problem component. I hadn’t installed the lights myself so I set to analyzing how they were installed, where the wires were routed, and how and where each component was grounded. All of the add-ons were installed together so I also needed to consider the IBS Dual Battery system, which was composed of a voltage display panel, and a 200-amp relay. The truck has a 24v starter so there are two 12v batteries under the hood that are run in series (as apposed to parallel) to create the 24v needed. They are isolated as 12v until the ignition is turned to the start position at which time the starter relay connects the two batteries and directs the 24v and the amperage to the starter. I am grossly simplifying this, but in essence that is how it works. The alternator provides charging voltage and amperage to the batteries when the engine is running. The IBS system ties the power from the alternator into the third battery in the back. Once the batteries under the hood are topped off, the 200-amp relay switched allowing voltage to reach the battery in the back. From the rear battery comes power that is tied to a fuse panel; where the wiring for each component exits. Each light has a wire running from the fuse panel to the assembly, as well as the inverter and the winch. I went ahead and checked all of the fuses and found them all to be good. I then checked voltage on each side of the fuse panel, before the fuse and after. Then I followed the wire to the switch and checked there. Then I followed the wire from the switch to the connector on the roof. So far all was good. At the connectors I was getting the necessary 12v the lights needed. So I opened the side of one of the lights and measured voltage at the point where the wires were soldered (attached) to the light itself. I got 3.4v. Ha? It all makes sense now, but boy did that baffle me in the moment. Ok, perhaps there is some sort of bad ground, raised resistance in the wire, or some other issue. I set to checking each one. With the light disconnected I checked continuity from the connector to the light – 0 ohms, which mean there was no resistance. Perhaps a short and power was somehow leaking out. I checked from the end of the power side to ground and got the infinity sign, or open which meant there was no short. I checked the ground again and there was no resistance to ground so the ground appeared to be just fine as well. Well, that stinks; maybe the light is busted? I disconnected the flood lamp and connected it to the power source for the spot. The light came on with no issues. I connected the spot to the power source for the flood and it didn’t come on. I tried all of the different power sources and the light wouldn’t come on. So, either the spotlights were busted or there wasn’t enough power getting to them. I just couldn’t believe that both spotlights could be broken right from the box. That seemed unlikely. I traced the ground for each of the spotlights and found that they shared a common ground. Ok, now this makes sense. The battery is an Optima Yellow Top with a low internal resistance. It is a deep cycle battery that also supplies 70 cold cranking amps. That means it could put out far more power in an instant than any LED lamp could ever hope to draw. So maybe it wasn’t a matter of whether the battery was flat or charged, but whether the ground – on the other end – provided enough contact and size to allow the needed amount of power to flow through. I unscrewed the bolt that the grounds were attached to and then wrapped a wire to the end of the ground leads for one of the lights. I wrapped the other end around the metal point the door latches to that is mounted through the vehicle frame. I threw the switch and the lights came on. So the roof rack was a suitable grounding point for the lower powered flood lamps, but didn’t provide enough continuity for the higher-powered spots. Now I just had to find a suitable ground point within reach of the two lights. I’ll end this here, but the roof rack could supply the ground, but only from the outside of the bolts. If I attached the wires over the bolt and place the nut on top then suddenly it wouldn’t work, but if I touched the outside of the nut then the ground worked fine. I just ran a wire from the bolt to another nut further across the rack and the light work fine now. They’re very bright and very cool! The rest of the day went by very quickly.
We were busy cleaning up our clothes, and cleaning up the truck. Holidays in Spain started and a big group of very loud Spanish people arrived in the evening; they were loud when they arrived, loud during the night (for whatever reason they were walking around with their flashlights) and loud the next morning, but were happy people. After we awoke we spent some time feeding the camels at the campsite used for overnight desert excursions.