Ambulance organization and wiring
Aug. 4th, 2015 08:48 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
sparr2015/08/03 Voltage shenanigans
After a week away, I got back to working on the ambulance. The new batteries lost a few mV while I was gone, a perfectly acceptable discharge rate with the small parasitic draw when the batteries are "disengaged" with the battery selector. I need to do a power audit once the wiring diagram is done, so I can eventually start leaving a battery engaged all the time. I went back to the battery store and picked up one of my two original batteries which they say is in decent shape. They recycled the other already, saying it was abysmally bad. I'll keep the good old battery in the back, for emergencies or projects.
A bunch of packages were waiting for me, with a bunch of parts and other goodies. I now have a peltier-cooled cooler, a kettle, and a crock pot, all 12V, which should make for much lower food costs on the road since we can keep and prepare meals now. I got replacement rubber grippers for the door-stays-open things, and they fit but they aren't great. I might need to replace the metal part that goes into them, too, since the old ones aren't quite the same shape as new ones. I did get one complete replacement kit, but couldn't install it because I want to re-use the old bolt holes and the new ones don't line up. A few minutes with a metal drill should solve that problem.
The real project for the night was trying to switch out the box dome lights from 25W incandescent bulbs to 1.2W LED "bulbs". Each bulb has 12 5050 LEDs on a cluster of PCBs all on top of a light bulb base. For the rest of this paragraph, one "LED" is one of those clusters. The swap seemed to start out OK, with the first couple of LED bulbs going in just fine. Things got weird at the end, though. Once I removed the last incandescent bulb, everything stopped working. One incandescent and five LEDs, almost everything works (one socket won't light an LED for some reason). Six LEDs, nothing works. One incandescent and one LED, both work. One LED, doesn't work. Two LEDs, doesn't work. I dug out my multimeter and poked and prodded a bunch of things. The six sockets are [apparently] all simply wired in parallel. With nothing plugged in, and power turned on, there's 12.5V between - and + in each socket, and 12.5V between the vehicle frame and + in each socket. Plugging in one incandescent bulb pulls the - wires up to 0.04V relative to the frame, which I will attribute to such long wires actually having resistance rather than existing in physics-experiment-land. Plugging in just one LED, on the other hand, results in the other sockets' - contacts getting pulled up to 6V. The remaining 6.5V causes just enough glow in the LED for me to tell it's on. One incandescent and one LED plugged in and the - wires are at about 2V, leaving 10V for the bulbs, which they both light up with. I think there's something wonky in the wiring between the power source and the sockets, maybe some electronics rather than just electrical connections. This problem may have to wait for me to make a wiring diagram, which I've been putting off for logistical reasons (read: the ambulance is packed with stuff and hard to move around in). The quick fix is to use one incandescent and 4-5 LED bulbs, hope I'm not overheating anything, and just accept the power loss for sticking with one incandescent (25+1.2*5=31W is a lot less than the 25*6=150W I was using before).
2015/08/04 Unpacking, exploring
Today I put a few hours into unpacking bins of misc into all the various storage areas of the ambulance, so that the bins could be done away with. Of the 9 bins I started with, I'm down to 6 now. I know one of those is going away once I sort out clothes and rope, and there's some space left in the storage cabinets, so I am hopeful that I'll be traveling with just four bins. 4 bins happens to be the right number to support the bed, so the logistics of living and working in the back are starting to look good. I found that a lot of the hinges are loose or misaligned on the interior doors and seats, with a lot of screws into stripped out holes in panels, wood, and metal. I might try to anchor threaded inserts into those holes, or I might just look for slightly bigger screws to re-thread the holes a little bigger.
After unpacking, I took out the firearm racks. Except for one hard to reach wire, which I was reticent to cut since I'll probably end up repurposing it, they were pretty easy to remove. All of the aluminum plates behind the racks unscrewed from the wall and unbolted from the floor easily. Some of the spacers on the floor were glued down, which required some percussive persuasion. A little cosmetic damage to the surfaces was inevitable. With all of that removed, I posted it on craigslist and eBay (which I haven't used in a decade, but am trying once again since they divorced from paypal), and hope to turn it into a bit more traveling funds. Worst case, I'll leave it in storage in Boston, and take a more leisurely approach to selling it once I'm there.
Removing the firearm racks gave me access to the largest flat wooden wall in the box. Looking into the wall through the exterior toolbox door had hinted at some dead space there, and some wiring, so I decided to remove the wall. Lo and behold, I found a full six inches of air between the interior wall and the exterior wall's studs, almost that much behind the cabinets, and more between one of the front walls and the driver's seat. I will definitely be cutting some holes in those walls to make recessed storage spaces. I might move the whole wall back 3-4 inches to make the main shelf area on that side deeper. The cabinets below that wall are already that deep.
Behind that wall I also found an abandoned switch panel, similar to the one on the dash. This answers a lot of questions, and raises more. It has a missing switch for "INTERIOR LOW", which might explain some of my wire-probing dimming the interior lights, and might also mean there's a dimmer or voltage divider somewhere that could be what has played havoc with my attempts to use LED bulbs. It has a switch for "SUCTION" which led me to find a 12V 52A(?!?) vacuum pump in some hidden cabinet space. I was not immediately able to test it. It has a switch for "INVERTER 115V AC" that has been disconnected. Nearby I discovered that the interior mains plugs are simply connected to a GFCI and breaker then out to the shore power port. I plan to add some heavy duty switching so I can use an inverter to replace the shore power, and to use shore power with a beefy 12V supply to replace using the battery. The panel has a switch for "BUZZER" which triggers the buzzer in the dash that I found previously. It also has three push-toggle buttons that make the white/yellow/red patient code lights on the dash light up. I suspect loose wires near this panel are why the yellow light has intermittently lit in the past.
While on a wire-following kick, I also got a look at the rats nests behind the seats up front. Behind the driver's seat there are two more terminal blocks with a couple dozen more small connections. There's also a "SURE POWER INDUSTRIES MULTI BATTERY ISOLATOR 1602", with some very beefy wires coming out of it. The manual for the device suggests that its job is to sit between the alternator and the two batteries and make sure they all play nice, particularly when the batteries are at different charge levels and are both engaged. I will do more reading on this. Behind the passenger seat is a box apparently made entirely of ventilation grilles, filled completely with heat sinks, with a bunch of wires bolted to the middle of the heat sinks. I am guessing that those bolts go to some small hot components embedded in the heat sinks. Unfortunately, the label on the box is mostly worn away, so all I know is that it's manufactured by Leece-Neville, just like some of the other components in the power distribution box. I'm going to ask reddit and the manufacturer to help me figure this one out, or maybe its purpose will become apparent when I trace all of the wires.
That's all for now. More news to come tomorrow! Maybe more organization, maybe more wire following, maybe the start of the actual wiring diagram.
After a week away, I got back to working on the ambulance. The new batteries lost a few mV while I was gone, a perfectly acceptable discharge rate with the small parasitic draw when the batteries are "disengaged" with the battery selector. I need to do a power audit once the wiring diagram is done, so I can eventually start leaving a battery engaged all the time. I went back to the battery store and picked up one of my two original batteries which they say is in decent shape. They recycled the other already, saying it was abysmally bad. I'll keep the good old battery in the back, for emergencies or projects.
A bunch of packages were waiting for me, with a bunch of parts and other goodies. I now have a peltier-cooled cooler, a kettle, and a crock pot, all 12V, which should make for much lower food costs on the road since we can keep and prepare meals now. I got replacement rubber grippers for the door-stays-open things, and they fit but they aren't great. I might need to replace the metal part that goes into them, too, since the old ones aren't quite the same shape as new ones. I did get one complete replacement kit, but couldn't install it because I want to re-use the old bolt holes and the new ones don't line up. A few minutes with a metal drill should solve that problem.
The real project for the night was trying to switch out the box dome lights from 25W incandescent bulbs to 1.2W LED "bulbs". Each bulb has 12 5050 LEDs on a cluster of PCBs all on top of a light bulb base. For the rest of this paragraph, one "LED" is one of those clusters. The swap seemed to start out OK, with the first couple of LED bulbs going in just fine. Things got weird at the end, though. Once I removed the last incandescent bulb, everything stopped working. One incandescent and five LEDs, almost everything works (one socket won't light an LED for some reason). Six LEDs, nothing works. One incandescent and one LED, both work. One LED, doesn't work. Two LEDs, doesn't work. I dug out my multimeter and poked and prodded a bunch of things. The six sockets are [apparently] all simply wired in parallel. With nothing plugged in, and power turned on, there's 12.5V between - and + in each socket, and 12.5V between the vehicle frame and + in each socket. Plugging in one incandescent bulb pulls the - wires up to 0.04V relative to the frame, which I will attribute to such long wires actually having resistance rather than existing in physics-experiment-land. Plugging in just one LED, on the other hand, results in the other sockets' - contacts getting pulled up to 6V. The remaining 6.5V causes just enough glow in the LED for me to tell it's on. One incandescent and one LED plugged in and the - wires are at about 2V, leaving 10V for the bulbs, which they both light up with. I think there's something wonky in the wiring between the power source and the sockets, maybe some electronics rather than just electrical connections. This problem may have to wait for me to make a wiring diagram, which I've been putting off for logistical reasons (read: the ambulance is packed with stuff and hard to move around in). The quick fix is to use one incandescent and 4-5 LED bulbs, hope I'm not overheating anything, and just accept the power loss for sticking with one incandescent (25+1.2*5=31W is a lot less than the 25*6=150W I was using before).
2015/08/04 Unpacking, exploring
Today I put a few hours into unpacking bins of misc into all the various storage areas of the ambulance, so that the bins could be done away with. Of the 9 bins I started with, I'm down to 6 now. I know one of those is going away once I sort out clothes and rope, and there's some space left in the storage cabinets, so I am hopeful that I'll be traveling with just four bins. 4 bins happens to be the right number to support the bed, so the logistics of living and working in the back are starting to look good. I found that a lot of the hinges are loose or misaligned on the interior doors and seats, with a lot of screws into stripped out holes in panels, wood, and metal. I might try to anchor threaded inserts into those holes, or I might just look for slightly bigger screws to re-thread the holes a little bigger.
After unpacking, I took out the firearm racks. Except for one hard to reach wire, which I was reticent to cut since I'll probably end up repurposing it, they were pretty easy to remove. All of the aluminum plates behind the racks unscrewed from the wall and unbolted from the floor easily. Some of the spacers on the floor were glued down, which required some percussive persuasion. A little cosmetic damage to the surfaces was inevitable. With all of that removed, I posted it on craigslist and eBay (which I haven't used in a decade, but am trying once again since they divorced from paypal), and hope to turn it into a bit more traveling funds. Worst case, I'll leave it in storage in Boston, and take a more leisurely approach to selling it once I'm there.
Removing the firearm racks gave me access to the largest flat wooden wall in the box. Looking into the wall through the exterior toolbox door had hinted at some dead space there, and some wiring, so I decided to remove the wall. Lo and behold, I found a full six inches of air between the interior wall and the exterior wall's studs, almost that much behind the cabinets, and more between one of the front walls and the driver's seat. I will definitely be cutting some holes in those walls to make recessed storage spaces. I might move the whole wall back 3-4 inches to make the main shelf area on that side deeper. The cabinets below that wall are already that deep.
Behind that wall I also found an abandoned switch panel, similar to the one on the dash. This answers a lot of questions, and raises more. It has a missing switch for "INTERIOR LOW", which might explain some of my wire-probing dimming the interior lights, and might also mean there's a dimmer or voltage divider somewhere that could be what has played havoc with my attempts to use LED bulbs. It has a switch for "SUCTION" which led me to find a 12V 52A(?!?) vacuum pump in some hidden cabinet space. I was not immediately able to test it. It has a switch for "INVERTER 115V AC" that has been disconnected. Nearby I discovered that the interior mains plugs are simply connected to a GFCI and breaker then out to the shore power port. I plan to add some heavy duty switching so I can use an inverter to replace the shore power, and to use shore power with a beefy 12V supply to replace using the battery. The panel has a switch for "BUZZER" which triggers the buzzer in the dash that I found previously. It also has three push-toggle buttons that make the white/yellow/red patient code lights on the dash light up. I suspect loose wires near this panel are why the yellow light has intermittently lit in the past.
While on a wire-following kick, I also got a look at the rats nests behind the seats up front. Behind the driver's seat there are two more terminal blocks with a couple dozen more small connections. There's also a "SURE POWER INDUSTRIES MULTI BATTERY ISOLATOR 1602", with some very beefy wires coming out of it. The manual for the device suggests that its job is to sit between the alternator and the two batteries and make sure they all play nice, particularly when the batteries are at different charge levels and are both engaged. I will do more reading on this. Behind the passenger seat is a box apparently made entirely of ventilation grilles, filled completely with heat sinks, with a bunch of wires bolted to the middle of the heat sinks. I am guessing that those bolts go to some small hot components embedded in the heat sinks. Unfortunately, the label on the box is mostly worn away, so all I know is that it's manufactured by Leece-Neville, just like some of the other components in the power distribution box. I'm going to ask reddit and the manufacturer to help me figure this one out, or maybe its purpose will become apparent when I trace all of the wires.
That's all for now. More news to come tomorrow! Maybe more organization, maybe more wire following, maybe the start of the actual wiring diagram.