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Camping Support Trolley – Some Build Progress

Since I do festivals every year, along with a couple of other camping trips if the weather is good enough, I’ve been taking equipment with me for years in flight cases to make things more comfortable. Things like a large battery to power lights & device charging, an old Eberspacher diesel heater for the times when the weather isn’t great, and an inverter to run the pumps built into airbeds.

Red Diesel / Heating Oil is my fuel of choice for camping purposes, as it’s about the safest fuel around, unlike Butane/LPG it is not explosive, will not burn very readily unless it’s atomized properly & it’s very cheap. Paraffin is an alternative fuel, but it’s expensive in the UK, at about £12 per 5L.
The Hexamine-based tablet fuels the UK festivals promote is nasty stuff, and the resulting combustion products are nastier still. (Things like Hydrogen Cyanide, Formaldehyde, Ammonia, NOX). They also leave a sticky black grok on every cooking pot that’s damn near impossible to remove. Meths / Trangia stoves are perfectly usable, but the flame is totally invisible, and the flammability of alcohol has always made me nervous when you’ve got a small pot of the stuff boiling while it’s in operation in the middle of a campsite filled with sloshed festival goers. A single well-placed kick could start a massive fire.

Previous System
Previous System

Over the years the gear has evolved and grown in size, so I decided building everything into one unit on wheels would be the best way forward. I’ve been working on this for some time, so it’s time to get some of the details on the blog! Above you can see the system used for last year’s camping, the heater is separate, with a 25L drum of heating oil, the battery is underneath the flight case containing all the power components, and it’s currently charging All The Things.

Overview
Overview

Above is the new unit almost finished, the bottom frame is a standard eBay-grade 4-wheel trolley with a few modifications of my own, with a new top box built from 12mm hardwood marine plywood. This top is secured in place with coach bolts through the 25mm angle iron of the trolley base. The essential carbon monoxide detector is fitted at the corner.

Internal View
Internal View

The inside gets a bit busy with everything crammed in. The large Yuasa 200Ah lead-acid battery is at the far end, with it’s isolation switch. Right in the middle is the Eberspacher heater with it’s hot air ducting. I’ve fitted my usual 12/24v dual voltage system here, with the 24v rail generated from a large 1200W DC-DC converter.

Heater Vent
Heater Vent

The hot air duct for the heater is fed out through a standard vent in the front. Very handy for drying out after a wet day.

Main Bus Bars & Solar Controller
Main Bus Bars & Solar Controller

Here’s a closeup of the distribution bus bars, with both negative rails tied together in the centre to keep the positives as far away from each other as possible, to reduce the possibility of a short circuit between the two when working on the wiring. The EpEver Tracer 4210A MPPT Solar Charge Controller is on the left, tucked into the corner. This controller implements the main circuit protection for the battery, having a 40A limit. Individual circuits are separately fused where required. Solar input on this unit is going to be initially provided by a pair of 100W flexible panels in series for a 48v solar bus, the flexible panels are essential here as most of the festivals I attend do not allow glass of any kind onsite, not to mention the weight of rigid panels is a pain.

DC Output Sockets
DC Output Sockets

I’ve stuck with the 3-pin XLR plugs for power in this design, giving both the 12v rail, 24v rail & ground.

Inverter Outputs
Inverter Outputs

Tucked under the DC outputs are a pair of panel sockets for the 600W inverter. This cheapo Maplin unit is only usually used to pump up air beds, so I’m not expecting anyone to pull anything near max output, but a warning label always helps.

Power Socket Wiring
Power Socket Wiring

Behind the front panel is the hardwiring for the power sockets. The DC jacks are connected together using 2mm solid copper wire, bent into bus bars.The mains wiring underneath is a simple radial circuit straight from the inverter. The large cylinder on the left is a hydraulic pump from a BMW Z3, which runs a hydraulic cylinder for lifting the lid of the top box, used simply because I had one in the box of junk.

Fuel Pump
Fuel Pump

External fuelling is dealt with by a small gear pump, this is used to fuel up the Optimus Stove & Petromax Lantern. This is in fact a car windscreen wash pump, but it has coped well with pumping hydrocarbons, it currently has a small leak on the hose connections, but the seals are still entirely intact.

Remote Relays
Remote Relays

There’s a small remote relay module here, for switching the DC output for lighting & the heater from afar. Very useful when it’s dark, since there’s no need to fumble around looking for a light switch. A car-style fob on my keyring instead.

Heater Timer
Heater Timer

Since the Eberspacher 701 controller I have is an ex-BT version, it’s very limited in it’s on time, a separate timeswitch is fitted to control the heater automatically. Being able to return to a nice warm tent is always a bonus.
Just to the left can be seen the top ball joint for the hydraulic cylinder that lifts the top of the box.

Battery Charger
Battery Charger

The final large component is the battery charger. This unit will maintain the battery when the trolley isn’t being used.

Router Motherboard
Router Motherboard

On the left side is the old Atom motherbaord used to provide a 4G router system. This unit gets it’s internet feed from a UMTS dongle & provides a local WiFi network for high speed connectivity. The bottom of the hydraulic cylinder is visible in the bottom right corner.

Fuel Tank Completed
Fuel Tank Completed

Since the Eberspacher obviously needs fuel, a tank was required. In previous years I’ve used jerry cans for this purpose, but this trolley is supposed to have everything onboard, for less setup time. The tank is constructed from 3mm steel plate, MIG welded together at the seams to create a ~40L capacity. The filler neck is an eBay purchase in Stainless Steel. No photos of the tank being welded together, as I was aiming to beat sunset & it’s very difficult to operate a camera with welding gauntlets on 😉

The tank is the same width as the trolley frame, so some modification was required, having the wheels welded directly to the sides of the tank. This makes the track wider at the rear, increasing stability.

Fuel Dip Tubes
Fuel Dip Tubes

A quick view inside the tank through the level sender port shows the copper dip tubes for fuel supply to the heater, and an external fuel hose for my other fuel-powered camping gear. These tubes stop about 10mm from the bottom of the tank to stop any moisture or dirt from being drawn into the pumps.

Fuel Feeds & Level Sender Port
Fuel Feeds & Level Sender Port

The top of the tank is drilled for the fuel fittings & the level sender and has already been painted here. The 1mm base plate has yet to be painted.

Level Sender Installed
Level Sender Installed

Touching up the paint & fitting the sender is the last job for this part. The mesh bottom of the trolley has been replaced by a 1mm steel sheet to support the other parts, mainly the heater. Fuel lines are run in polyurethane tubing to the fuel pumps.

All the instruments & controls are on a single panel, with the Eberspacher thermostat, external fuelling port & pump switch, inverter control, the solar controller monitor panel, cover buttons, router controls, compressed air & fuel gauges.

Panel Wiring
Panel Wiring

As is usual behind instrument panels, there’s a rat’s nest of wiring. There’s still the pressure gauge to connect up for the compressed air system, and the nut on one of the router buttons is such a tight fit I’ve not managed to get it into place yet.

Eberspacher Fuel Pump
Eberspacher Fuel Pump

The support components for the Eberspacher heater are mounted underneath the baseplate, with the fuel dosing pump secured to a rail with a pair of cable ties, and some foam tape around to isolate the constant clicking noise these pumps create in operation. The large black cylinder is the combustion air intake silencer, with the stainless steel exhaust pipe to the left of that. Silencing these heaters is essential – they sound like a jet engine without anything to deaden the noise. Most of this is generated from the side-channel blower used in the burner.

Eberspacher Exhaust
Eberspacher Exhaust

Bolted to the underside are a pair of exhaust silencers, one is an Eberspacher brand, the other is Webasto, since the latter type are better at reducing the exhaust noise. Connections are sealed with commerical exhaust assembly paste, the usual clamps supplied do not do a good enough job of stopping exhaust leaks.

Next update to come when I get the parts in for the air compressor system.

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103RS GPS Tracker Teardown

Rewire Security 103RS Tracker
Rewire Security 103RS Tracker

I thought it was time to add a bit of security to the gear I take camping, so this GPS tracker unit was sourced from eBay. This is a Rewire Security 103RS, a slightly customised version of the common Chinese TK103 GPS tracker.

Input Connections
Input Connections

The small module has all it’s power connections on one end of the unit, on a Molex multi-way block. The white connector is for a piezo-shock sensor – this interfaces with the alarm functionality of the unit. There’s an indicator LED for both the GPS & GSM status, and a switch for the backup battery.

Antenna Connections
Antenna Connections

The other end has the antenna connections, microphone connection for the monitor function, along with the SIM & SD card slots.

PCB Top
PCB Top

Once the end panel is removed, the PCB just slides out of the aluminium extruded casing. It’s pretty heavily packed with components in here. A switching regulator deals with the 12v input from the vehicle battery, and is protected by a polyfuse on the right. The GSM module is hiding under the Li-Po backup cell, unfortunately the sticky pad used to secure this wouldn’t come off without damaging something. The pigtails for both the GPS & GSM antennas are permanently soldered to the board here.

PCB Bottom
PCB Bottom

The bottom of the PCB has the GPS module, and mainly input protection & bypassing components. There is a FNK4421 Dual P-Channel MOSFET here as well, probably used for switching the external relay or alarm siren. The SIM socket for the GSM modem is located here in the corner.

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EpEver Tracer 4210A MPPT Solar Charge Controller Teardown

Tracer 4210A MPPT Solar Controller
Tracer 4210A MPPT Solar Controller

Here’s the solar charge controller to go with the MT50 from the last post. This is the 40A version of the EpEver Tracer A series, the 4210A. This unit is large, and very heavy. Most of this weight comes from the enormous heatsink which doubles as the mounting plate for all the other components, and the large inductors that are going to be required for the DC-DC conversion that MPPT requires.

Front Panel
Front Panel

The front panel has a basic LCD, which shows various stats, such as PV Volts & Amps, and battery bank Volts & Amps. The pair of buttons are used to navigate the basic menu to configure some options, along with switching the load terminals ON/OFF.

Specifications
Specifications

There’s a specs label on the top, with a slight difference here vs the manual, which states the max. PV volts as 92v.

Main PCB Overview
Main PCB Overview

Removing 4 machine screws from the bottom of the unit allows the top to come off. Like the MT50 remote panel, this unit also has moulded-in brass thread inserts in the plastic parts. The PCB in here is heavily comformal coated, which stops me from reading the laser-etched numbers on the semiconductor devices, so there will be few details there.

Main PCB Lower
Main PCB Lower

Here’s the bottom section of the main PCB, with the enormous screw terminals, which will easily take cables up to about 16mm². The RJ-45 jack which hosts the unit’s RS-485 bus is to the right, and a smaller 2-pin connector on the left sorts out the battery temperature sensor.
The DC output MOSFET switches are hiding just behind the right-hand terminals, there’s a pair of them in this unit to handle the output current. Some beefy diodes polarity-protect both the battery & PV inputs.

Board Centre
Board Centre

Moving up the board shows two 35A automotive blade fuses soldered into the board – these would be a real pain to replace if they ever blew, however with the electronic load current protection built into this unit, it’s an unlikely situation, unless something went hideously wrong. The main switching devices for the DC-DC converter are hidden – they’re clamped to the heatsink with the bars at right angles in the photo, I’m not going to dig any deeper into this just for those though – they’re just TO220 devices.
Under a load of thermal gunk on the right are 4 current shunt resistors, and the amplifiers for reading their values. These 1206-size SMD resistors looked a bit small for the power rating to me, but they’re heatsinked in operation to a small heatsink mounted in the top cover.

Board Upper
Board Upper

The upper section of the PCB hosts the main microcontroller, and the connections over to the front panel LCD & buttons. Couldn’t really get much info from these chips, due to the conformal coating.

Toroidal Inductors
Toroidal Inductors

Right at the top of the unit are these toroidal inductors, potted into aluminium housings. The copper windings of these is very heavy – at least 2.5mm². They’re electrically in parallel, the 20A version would only have a single inductor.

Current Shunt Heatsink
Current Shunt Heatsink

This small heatsink sits inside the top cover, and provides some cooling to the current shunts.

Display Board
Display Board

Not much to say for the display board, there’s going to be nothing here apart from an I²C LCD driver & the pair of front panel buttons, so I won’t bother removing this from the case.