Project: DA PIMP - POWER IN MY POCKET Date:April 2012
Da Pimp is a extremely portable battery tester / desulfator / charger.
It uses capacitors instead of a transformer creating a highly
efficient conversion of AC to DC voltages. It is available fully
assembled with all accessories or as a complete kit that requires
Da Pimp is ideal for the following:
rapid testing of batteries to determine how sulfated they are
recovering lead-acid car starting batteries
recovering marine boat batteries
recovering entire sets of lead-acid deep-cycle battery banks ( golf carts, forklifts, other electric vehicles and pv solar systems )
recovering power tool batteries (drills, weed wackers, saws)
"Captivating right from the start." - Boing Boing,
"Stop whatever you’re doing and get this book." - Hack A Day
The design is completely open with source code, schematics, circuit layout and bill of materials all made available.
Usage: [WARNING: SHOCK HAZARD]
Never handle the leads while black switch is set to 1 (on).
confirm that the black switch is set to the 0 position (off)
connect the black lead to the battery negative
connect the red lead to the battery positive
turn on the silver toggle switch (display should show battery voltage)
plug power cord into outlet
turn on black switch - set to 1 position (on)
battery is charging
watch to confirm voltage is slowly rising
turn off silver toggle switch when charging for extended periods (this will save the 9V battery life)
turn off the black switch - set to 0 position (off) to end charging
Charge for 15 minutes
Periodically Check the Voltage (toggle silver switch)
It will probably go well over the nominal (9v / 12v / 18v) of the battery
You should see the voltage spike high maybe up to 99V, but then drop to the packs rated voltage
The dropping voltage during charging is the sign of a battery being recovered
Let the battery rest for a few hours or overnight and check on it the next day
If it is below it's rated voltage charge again and increase from 15min to 1hour
Stop charging if there is significant heat
Power Tools Charge for no more than 2-4 hours (charger outputs 500mA, and power tools battery are usually less than 2000mA)
12V batteries be sure to add water (even for sealed-lead-acid) before charging
Full size car and golf cart batteries can take up to 4-5 days of charging
Clip the small alligator clips into larger store bought clips when charging large batteries
Return to factory charger once battery performance improves
Input: 120VAC or 220VAC
Output: .5A constant current output dynamic voltage 1VDC - 100VDC
Output for 220V connections is 1A
Question:What do you use for international shipping?
Answer:This item ships via USPS First-Class International Mail. It provides some tracking and is usually 10-14 days for delivery.
Question:How does the desulfation part work?
Answer:Da Pimp is making use of a 60Hz AC signal for charging it still has a pulse after the DC conversion. It's the pulse that does the desulfation. This is a automatic process that occurs whenever a battery is charging with Da Pimp.
Question:Can all batteries of the chemistries you have described be recovered?
Answer:No. These are the most common three cases where a battery is not going to be recoverable:
Hard Sulfation - the battery has sat for so long that it cannot pass current through itself and starts to heat up during charging
Single Cell Failure - one battery cell has died within a pack so no matter how much you charge it the cell cannot maintain a reasonable charge
Internal Break - internal wiring between battery cells has been compromised and current cannot pass through the battery
Question:I live outside the US and have 220VAC can I use that with Da Pimp?
Answer:Yes. Da Pimp works with 120VAC or 220VAC. You will need a cheap prong adapter to convert the plug style, but you do not need to step down the voltage. The important difference to note is the output current will double when using 220VAC. In the US Da Pimp puts out 500mA internationally it will put out 1A.
Question:How about rechargable AA cells of NiMH or NiCD chemistry can I charge those?
Answer:No. Those small types of cells generally like to be charged around 200mA and Da Pimp will put out 2x to 4x the amount of current they "like" to be charged at.
Question:How does Da Pimp know what voltage to output?
Answer:Da Pimp outputs whatever voltage is necessary to get over a batteries internal resistance. A good 12V sealed lead acid battery might have a voltage of 12.6V. Da Pimp will slowly increase that voltage to 12.9V, 13.0V, 13.1V, etc. You will want to turn off Da Pimp off when voltage reaches 14V.
Question:Why capacitors instead of a transformer?
Answer:Capacitors provide many advantages over a transformer.
they are efficient (60% more so than comparable transformers)
there is no noise, no heat
they are light
they produce a nice pulse (ideal for desulfating old batteries)
they can be inexpensive
Question:Did you invent this?
Answer:I did not invent the concept of capacitive charging. A friend turned me onto a white paper from 1996 entitled "Capacitive Battery Charger" written by George Wiseman's of Eagle Research. I was skeptical, but intriged. I wanted to add more to his design making it safer and more accesible to the masses. Thus this project was born.
Question:How do I test a battery?
Answer:Connect Da Pimp using the above instructions. When the black switch is turned on does the voltage rapidly jump? If so, you have a bad battery. A good battery will have a slow voltage climb maybe just a few 1/10ths of a volt when the charger is enabled. The voltage difference before and after the charge is started indicates how much resistance has built up inside the battery (sulfation).
Question:How do I recover a battery?
Answer:Connect Da Pimp using the above instructions. Note the voltage jump that occurs when the black switch is enabled (1) causing Da Pimp to be charging. The difference in voltage jump should become reduced between charges. A desulfating pulse will occur during the charge process.
Question:How do I know when to stop charging?
On a good battery I like to stop the charge at 120% the nominal voltage. If we look at a 12V battery that would be 14.4V (12V * 1.2 = 14.4V). On a weak or bad battery it is possible to exceed the 120% rule for brief periods, but please be mindful of heat and that a battery can explode if overcharged for too long.
Question:Will Da Pimp automatically stop charging?
Answer:No. It will charge until you shut off the black switch (0).
Question:Can I charge lithium batteries?
Answer:Yes, lithium can be charged. It is one of the easiest chemistries to bring back to normal voltages. However, please be very careful. Never exceed 10% over nominal with Li packs. They can take up to 20% over nominal, but let's avoid blowing up batteries. Once you have charged the pack to 10% over let the devices standard charger take over. Do not leave lithium unattended while recovering.
Question:What happened to K1 (the relay)?
Answer:I removed the relay K1 after seeing that the capacitors were welding the relay armature. It is not being used. All PCBs include a slight modification to the K1 footprint with jumpered connections.
Step by Step Kit Assembly:
These instructions are for Da Pimp.
Note: This kit makes use of mains power - 120VAC-220VAC. Do not plug the 2 prong power cable into wall socket until assembly is complete and circuit is verified to work.
Step 1: Blank PCB
Step 2: Place and solder resistor (R1) - 10k ohm
Step 3: Place and solder resistor (R2) - 510 ohm
Step 4: Place and solder 7 segement display (D1)
Step 5: Place and solder 2 pin JST connector (CONN1)
Step 6: Place and solder 10 pin ISP Header (J1)
Step 7: Place and solder 28 pin microcontroller (U2)
Note:The small impression must be near the right edge of the circuit board.
Step 8: Place and solder fuse holders with fuse installed (F1)
Note:The fuse holders have slots for the fuse to cleanly mount in.
Step 9: Place and solder capacitors (C1, C2, C3)
Note:Orientation does not matter.
Step 10: Place and solder metal toggle switch (S1)
Note 1:Remove the nuts and washers we won't need them
Note 2:Orient the groove cut through the threads to the top of the PCB (towards the 7-segment display)
Note 3:Pinch the leads and sink the switch as deep into the PCB as you can while soldering (I botched the footprint on this one)
Step 11: Place and solder 2 pin JST connector (CONN2)
Step 12: Place and solder bridge rectifier (U3)
Note:Orient the + sign to match that of the white plus sign on the silkscreen for U3
Step 13: Place and solder large black rocker switch (S4)
Note:Orient the 0 and 1 to match the silkscreen equivalents
Step 14: Place and solder 7805 5V voltage regulator (U1)
Note:Orient the text on the 7805 to be facing the black rocker switch
Step 15: Place and solder decoupling caps (C4, C5)
Note:Orient the minus sign on capacitors to the bottom of the circuit board
Step 16: Place and solder mini JST (B1) used for 9V battery connection
Step 17: Cable Up
Note 1: Top left cable is AC plug
Note 2: Lower left cable is DC charging leads
Note 3: Bottom rigth cable is 9V DC battery plug
Step 18: Place bolts through case and circuit board mounting holes
Step 19: Place spacers and plexiglass over bolts.
Step 20: Lightly tighten down nuts and place 9V battery inside enclosure.
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