Salvaged air compressor from Stanley Fatmax Jumper

Thread Starter

Teljkon

Joined Jan 24, 2019
153
I had a Stanley Fatmax 700 Jumper box, not the exact box linked bellow but basically the same thing minus a couple of USB ports.

https://www.homedepot.com/p/Stanley-Jump-Starter-700-Peak-350-Instant-Amps-120-PSI-Air-Compressor-J7CS/306184808?MERCH=REC-_-PIPHorizontal2_rr-_-202188376-_-306184808-_-N

So I went to jump my car and nothing taped the leads no sparks. At the time i was curious wtf was wrong and set the thing aside for a charge no luck still after two days. Compressor worked threw all of this but not the leads. So ok i set it aside on the work bench and wait for some time to crack it open. Pop it I know I am not going to fix it beyond throwing a new batter in it this is still beyond me. Throw a tester reads 12v rated 12v ok not the battery decide I will just break it down and salvage the compressor and battery.

Kept the PCB just so i could decode how the compressor was connected latter. Here is what i ran into. I hooked the compressor up multiple times to my PSU. I have barley gotten it to move make more than a chirp. When the switch is flipped the light on my PSU will turn off, if the rating on the switch is right its 120v meaning maybe i need capacitor or booster circuit of some kind. The other thing that I think might help is a soft start circuit. Obviously I am noob with this stuff just trying to learn. Hope I can get some help here.

 

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drc_567

Joined Dec 29, 2008
867
Compressor worked threw all of this but not the leads.
... just to clarify ... It has been demonstrated that the compressor has worked off of the original battery pack ... is that correct? But the jumper leads do not seem to connect to the battery and allow you to jump start the car ... correct? So the battery pack is working, but something else is wrong ... possibly the thermal cut-out circuit protection device that is mentioned ... correct so far?
 

wayneh

Joined Sep 9, 2010
16,399
A couple things. First, a charger may not start charging a battery that is stone cold dead. The charger needs to see a bit of voltage to make it kick in. This prevents the leads from shorting when accidentally touched together. I sometimes hook it up and briefly touch another battery to it to get it going.

Second, your PSU probably isn’t rated to high enough current to run the compressor. The PSU sees it as a short.
 

Thread Starter

Teljkon

Joined Jan 24, 2019
153
... just to clarify ... It has been demonstrated that the compressor has worked off of the original battery pack ... is that correct? But the jumper leads do not seem to connect to the battery and allow you to jump start the car ... correct? So the battery pack is working, but something else is wrong ... possibly the thermal cut-out circuit protection device that is mentioned ... correct so far?

Correct but that is kind of moot as I pulled the good 12v lead acid battery and at this point I am just trying to salvage the compressor. Or are you saying I should try cutting that thing off the lead? If so I already jumped over it with a few alligator clips admit idly it the wire gauge was smaller but a figured two of them would make up for that.
 

Thread Starter

Teljkon

Joined Jan 24, 2019
153
A couple things. First, a charger may not start charging a battery that is stone cold dead. The charger needs to see a bit of voltage to make it kick in. This prevents the leads from shorting when accidentally touched together. I sometimes hook it up and briefly touch another battery to it to get it going.

Second, your PSU probably isn’t rated to high enough current to run the compressor. The PSU sees it as a short.

This would make sense, the light for 12v led just cuts out when i try to activate it so what I need to do is create a circuit that ups the current high enough to run the compressor. I will duck duck go some circuits and see if i can figure this out thank you for the help. Should be a good learning project.

However I have to say i disagree with the assessment of the jumpers the pack was also showing for three days on a wall outlet just the red charging LED meaning it wasn't charging. If it flipped over the board pictured for you the other side has IC's and micro controllers on it some with corrosion. Sad to admit my SUV holds moisture said moisture must have killed the darn thing. I was really surprised though at the size of the Capacitors on the board they are allot smaller than I thought I would find. Considering it jumps a car battery. I figured I would find two large ones in some kind of switching circuit to deliver couple minutes of guaranteed charge.
 

drc_567

Joined Dec 29, 2008
867
... If the compressor worked previously, it would seem that it ought to work if it were hooked up as a separate component ... no pcb attached. Wiring error of some sort?
Red wire ought to go to battery positive and black wire to negative ... is there anything else that might be the problem? ... Maybe that protection component is faulty ... open circuit ... can you check it for continuity?
 

Thread Starter

Teljkon

Joined Jan 24, 2019
153
wow apparently I cant type after 11!

*admit-idly the wire gauge was smaller but I used two gator clips to compensate.
 

Thread Starter

Teljkon

Joined Jan 24, 2019
153
... If the compressor worked previously, it would seem that it ought to work if it were hooked up as a separate component ... no pcb attached. Wiring error of some sort?
Red wire ought to go to battery positive and black wire to negative ... is there anything else that might be the problem? ... Maybe that protection component is faulty ... open circuit ... can you check it for continuity?

I am afraid i do not have a continuity checker my inexperience very well means I may have created an open circuit and I do not know it. Let me Hit the work bench and see if i can hook right up to the battery. As soon as I get this cat out of my lap.
 

Thread Starter

Teljkon

Joined Jan 24, 2019
153
Ok so this is the rub when i touched it to the battery it immediately jumped to life. Crushed my finger didn't realize the indent in the back that held the piston wasn't guarded who knew. hahahahaha

So, clearly the current on my PSU is to low as weyneh mentioned and drc was hinting at. Meaning i need to make a circuit that steps up the current to play with it on the work bench. Thank you for the help I need to hit duck duck go.
 

wayneh

Joined Sep 9, 2010
16,399
Does your power supply also have 5V? Computer power supplies usually have much more capacity at 5V than they do at 12V. The compressor may run better on low voltage as long as it gets plenty of current.
 

Thread Starter

Teljkon

Joined Jan 24, 2019
153
my Power supply dose have a 5v connection. Ill give that a try. let me ask you would a couple resistors in parallel on a bread board work to up the current? Am I barking up the right tree? The other option is to get a diode kit and salvage a few capacitors.
 
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Thread Starter

Teljkon

Joined Jan 24, 2019
153
Mistakes or contradictions like these make electronics confusing. Look at the info graphic right under the paragraph that literally says resistors in parallel increase current. my interpretation of the graphic is the same current in the same current out.

current in =14amps
current out = 14amps

the paragraph above literally says the opposite what is correct.

https://www.physicsclassroom.com/class/circuits/Lesson-4/Parallel-Circuits
 
Last edited:

wayneh

Joined Sep 9, 2010
16,399
Mistakes or contradictions like these make electronics confusing. Look at the info graphic right under the paragraph that literally says resistors in parallel increase current. my interpretation of the graphic is the same current in the same current out.

current in =14amps
current out = 14amps

the paragraph above literally says the opposite what is correct.

https://www.physicsclassroom.com/class/circuits/Lesson-4/Parallel-Circuits
It's true that the total current flowing through a bank of resistors will increase with each added resistor, as long as the supply can keep up. It's like increasing the diameter of a pipe. BUT, you need an unlimited source of current for that to be true. There's nothing you can do with circuitry to get more current from the supply than it is capable of. Well technically you could transform a voltage to a lower voltage at higher current, but you lose power each time you make a transformation. You don't gain anything. A computer PSU can usually deliver quite a bit more current and total power on the 5V part. The 12V part usually has a much lower current rating.
 

Thread Starter

Teljkon

Joined Jan 24, 2019
153
It's true that the total current flowing through a bank of resistors will increase with each added resistor, as long as the supply can keep up. It's like increasing the diameter of a pipe. BUT, you need an unlimited source of current for that to be true. There's nothing you can do with circuitry to get more current from the supply than it is capable of. Well technically you could transform a voltage to a lower voltage at higher current, but you lose power each time you make a transformation. You don't gain anything. A computer PSU can usually deliver quite a bit more current and total power on the 5V part. The 12V part usually has a much lower current rating.
Ok so I am in capacitor diod territory for sure. It must be possible to step up the 5v side and 3v side to 12v but I would, if I am understanding things correctly, be doing that at the expense of current. defeating the purpose. While this isn't what i set out to learn. I am getting a better grasp on how current works in a circuit thank you.
 

Thread Starter

Teljkon

Joined Jan 24, 2019
153
I actually tried dumping the 3v and 5v into a resistor bridge and pick it back up off the other side no joy. kinda knew that wouldn't work but wtf why not.
 
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