Read The Disclaimer
SP4 Portable Solar Panel/Battery Recharging Kit: Power Pass-Through Modification
Right: A soldier setting up modified SP4 panels to run a wireless surveillance system 24/7 in Anbar Province, OIF
The SP4 is a folding, soldier-portable solar panel system intended to allow soldiers to recharge the tan colored BB-2590 (SINCGARS/ASIP) rechargeable military battery. In good sunlight, an SP4 system can charge a fully discharged BB-2590 in roughly 6 hours, one battery which in turn can run an PRC-119F (ASIP) for 31 hours, two batteries can run a PRC-117F for 17 hours, and two batteries can run a PSC-5D for 12 hours.
Field modifications can be made, however, to allow the panel to both charge a battery and power an external device at the same time, and, furthermore at night, to continue to power the device directly off of the charged battery. For higher power drain devices, multiple modified SP4s can be daisy-chained together to provide continuous, 24/7 power. Applications include radios at remote OPs and unattended sensors such as wireless camera systems. Interested in this pass-through? Here's how you do it. [Note: this pass through modification concept has been approved by CERDEC, and they are implementing it in future SP4 systems. Expect all new SP4 systems to have this capability by mid-2007.]
Tools
| Tool |
| Dremel |
| Drill |
| Phillips Screwdriver |
| Wire Stippers |
| Hacksaw (or Dremel cutting discs) |
| Voltmeter / Multimeter with Continuity (Bell) Function |
| **Hole Punch (e.g. PN 3424A19 from www.mcmaster.com) |
| **Rivet Gun (e.g. PN 95585A100 from www.mcmaster.com) |
Supplies
| Part | Source | Part Number | Cost |
| SP4 System (x1) | Bren-Tronics or Global Solar |
SP-4 | ~$1200 each |
| Male 5590 Connector - Bare (x1) | www.baiaerosystems.com/connect.html | BAI-106G | $15/each; less in bulk |
| Female 5590 Connector - Bare (x1) Alternate: scavenge one out of dead BA-5590 battery |
www.tacticaleng.com | CONN-BA5590-F | $14.75 each |
| Diodes (x4) | www.digikey.com | sk32-7 | $0.86/each; less in bulk |
| 2-Conductor Wire (3 feet) | www.mcmaster.com | 8237K11 | $1.60/ft |
| Epoxy (gel is best) (x1) | www.mcmaster.com | 7592A31 | $5.33/tube |
| Ziptie (x1) | All over theater. Try the MPs... | ||
| *Rubber Grommet (x1) (optional) | www.mcmaster.com | 9307K14 | $4.64 for 10 |
| **Velcro Strap (x1) (optional) | www.mcmaster.com | 3955T355 | $6.50 for 5 |
| **Rivet (x1) (optional) | www.mcmaster.com | 97530A060 | $10.62 for 100 |
| **Rivet Backing Washer (x1) (optional) | www.mcmaster.com | 90183A316 | $5.77 for 100 |
| ***Polycarbonate Tube, 0.625" ID, 0.750" OD, (2 inches), (optional) |
www.mcmaster.com | 8585K13 | $1.43 per foot |
| ***Heat Shrink Boot (x1) (optional) | www.mcmaster.com | 73575K61 | $13.09 each |
*, optional: You can dab some epoxy around the cable coming through the hole.
**, optional: If you choose not to attach the velcro strap, you MUST tape the battery cap onto the battery, or it will slip off/disconnect over time.
***, optional: You can blow off the nice heat shrink boot and polycarbonate tube strain relief if you use some epoxy at the back of the female x90 connector to hold stuff in place and then wrap lots of electrical tape around it.
Directions
1. Prep and Attach Velcro Retaining Strap
Remove the four Phillips head screws from the charge cap (the black cap that attaches to the top of the battery). Separate the top and bottom halves of the cap by feeding the wire cable through the existing grommet. On the top of the charge cap drill a hole in the middle for the rivet holding the Velcro strap, with a diameter ranging from 0.192 - 0.205". Using a ¼"-hole punch, such as a mcmaster.com PN 3424A19, place a hole in the Velcro strap (McMaster.com PN 3955T355) so that the strap buckle is on the flat side of the battery while in position.
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| Velcro strap attached to top of charge cap. |
Align the hole in the strap with the hole in the top of the charge cap, and place the rivet (mcmaster.com part number 97530A060) through the hole. Place a rivet backing washer (mcmaster.com PN 90183A316) on the inside of charge cap over the rivet, and using rivet gun (such as mcmaster.com PN 95585A100) and crimp the rivet tightly.
2. Insert Pass Through Cable into Charge Cap
4) On the side opposite the existing charge cable, drill a 0.375" hole in charge cap top. Place a rubber grommet, such as mcmaster.com PN 9307K14, inside the 0.375" hole. Cut and slide a 27" length of 2 conductor wire (mcmaster.com PN 8237K11) through the grommet to form the "pass through" cable. Strip the insulation of the wire inside the charge cap back approximately 1.25"; cinch a zip tie around the insulation of the cable so that it can't pull back through the grommet.
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| Inside of charge cap top showing new grommet in the center and inserted wire with zip tie coming in from the right. |
3. Attach Diodes and Pass Through Cable
Attach diodes (digikey.com PN sk32-7) to pins 4 and 5 of the bottom charging cap. Note that you MUST have the diodes oriented properly; power will only flow one way: TOWARDS the end with the white line. Since we want to draw power from the battery/charger (but not send it back in), the side of the diode without the line on it is the side soldered directly to the pins. Make sure you join the two "free" ends of the diodes (with the lines on them) together.
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| Diodes attached to pins 4 and 5; the diode ends with the line are connected together. |
Attach the two wires from the stripped end of the new pass through cable to the diodes (+) and ground (-) pins. The red (+) wire is attached to the ends of the diodes, and the black (-/ground) wire is soldered to both pins 1 and 2. Slide the wire cables until the charge cap connector fits into place, and replace the four Phillips screws.
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| Overview of diodes and attached wires from the pass through cable. |
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| Finished cap attached to a BB-2590 battery |
4-6. Make Daisy-Chain x90 Connector Extension
Follow steps 1-3 for wiring the 5590 connector here, using a 7" length of two conductor wire (mcmaster.com PN 8237K11).
7. Prep Female x90 Connector Assembly
Cut a 1.125" long piece of polycarbonate tube (0.625" I.D. x 0.75" O.D., (mcmaster.com PN 8585K13), and pre fit the tube over the white female x90 connector. Some bosses on the white connector may need to be removed with a dremmel tool to ensure good contact between the tube and connector. Do not attach the tube yet; you're just getting the fit correct.
8. Slide Cable End Components Together
Prior to soldering the female x90 connector, slide the heat shrink boot and the tube over the wires as shown in the following picture
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| Assembled cable end components after the female x90 connected is soldered on (next step). |
9. Attach Female x90 Connector
Strip ~1" of the outer jacket off the free ends of both the 27" pass through cable and the 7" daisy-chain cable. Strip the ends of the indidual wires back just enough to make solder contact with the pins on the back of the white female x90 connector.
The black (-) wire on the long pass through cable is soldered to pin 1, and the red (+) wire onto pin 4. For the shorter daisy-chain cable, the black (-) wire is attached to pin 2 and the red (+) wire to pin 5.
Verify that all your connections and diode placements are proper using the following table. You will use the continuity (bell) function on the multi-meter. It is very important that you understand how to do this correctly when working with diodes. On most most multi-meters, the continuity checker can also be used to determine if your diodes are oriented in the correct direction. The continuity check effectively "flows" from the red/+ probe to the black/- probe. Thus if you were to take a single, unattached diode and try a continuity test, you'll only hear a "ring" when the red probe is on the non-line side and the black probe is on the diode side with a line. If you reverse them, the multi-meter will not "ring." Try it on a diode to verify this.
Thus, when using the following table to verify that your your connections are correct, you must place the red/+ probe of the multi-meter on the side of the connection to which the battery would attach, and the black/- probe on the contacts on the white female x90 output connector.
| Battery Side (use red/+ multi-meter probe) | White Female x90 Connector Side (use black/- multi-meter probe) |
| Charging Cap: pins 1 and/or 2 ring ONLY to: | Female x90 Output: pin 1 |
| Charging Cap: pins 4 and/or 5 ring ONLY to: | Female x90 Output: pin 4 |
| Daisy-Chain Male x90 Connector: pins 1 and/or 2 ring ONLY to: | Female x90 Output: pin 2 |
| Daisy-Chain Male x90 Connector: pins 4 and/or 5 ring ONLY to: | Female x90 Output: pin 5 |
10. Finish Female x90 Connector End
Epoxy the base of the polycarbonate tube to the female x90 connector to keep it in place. When it has hardened a bit, pot (fill) the polycarbonate tube with epoxy to keep the wires in place and solid.
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| Female x90 connector with tubing attached and filled with epoxy |
Slide the heat shrink boot over the assembly and shrink it with either a heat gun, or you can use the hot side of the soldering iron if you don't have a heat gun. The tube will shrink down and provide strain relief for all the cables. If you don't have a heat shrink boot, multiple wraps of electrical tape can hold the system together and provide the required strain relief.
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| Heat shrink boot attached to female x90 connector |
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| Completed system (without the velcro strap) |
11. Test and Verify
- Attach a tan-colored BB-2590 to the charge controller cap.
- Using a multi-meter, check the voltage output on the female x90 connector on your pass-through cable. Pins 1(-) & 4(+) should give a voltage between 12 and 16.5V, while pins 2 & 5 should have no output voltage.
- Remove the BB-2590 from the charging cap, and connect it to the male x90 daisy-chain connector on the pass-through cable. Using a multi-meter, check the voltage output on the female x90 connector on your pass-through cable. Pins 2(-) & 5(+) should give a voltage between 12 and 16.5V, while pins 1 & 4 should have no output voltage.
12. Usage Notes / TTPs
- The SP-4 will ONLY charge the tan-colored BB-2590 batteries; it will not work with the green BB-390 rechargeables.
- Due to the way the electronics are set-up, you MUST have a BB-2590 battery attached to the charger to be able to get pass-through power out of the new pass-through cable.
- Using only one panel, you can only get 12-16.5V output. For full 24-33V output, you must have a minimum of two panels.
- The solar panels were optimized for just charging a battery, thus the power output over and above the energy needed to charge the battery is not large. You may have to simply daisy-chain numerous SP-4 systems together to run higher drain 12V-type devices 24/7. Furthermore, because daisy-chaining has only one SP-4 power to pins to 1 & 4, while all the other panels send power to pins 2 & 5, high drain 24V applications may not work well at all. The way to deal with this is to split your multiple panels into two sets of daisy-chained panels (e.g. two separate sets of four panels). Then make a new Y adapter which takes the output from one set of four panels and sends the power to pins 1 & 4, and takes the power from the other set of four panels and sends it to pins 2 & 5, thus balancing the power output from all eight panels for 24V applications.