Help? Using a jump pack as a jump pack instead of launch power supply

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Marc_G

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Hi folks,

My jump starter doesn't work, in that the positive cable gets no power. Is this thing worth opening up to attempt to find the problem and fix? Note that it works fine to launch rockets; I use the accessory plug port on it and that's still OK. It just doesn't work as a car starter.

It's a Walmart-sourced Instant Power [yeah, right] XP500. Manual is here. I've read the manual; I'm doing it right. It did work once, when my wife left her lights on. So, not a major manufacturing defect.

I was at a club launch a month ago and they had power troubles with their main battery; I offered my jump pack, but we couldn't get it working. That was odd since I launched with it the day before. Investigation showed the accessory port I use was drawing power fine, but the club would attach via the cables instead and they weren't working. (Yes, I turned the thing on, and tried the switch both ways...).

Last night I finally got down to some troubleshooting and found that the positive cable/clip is never energized no matter what position the switch is in. The negative cable is connected; if I use my voltmeter on the negative cable and the positive button in the accessory port I can get voltage readings.

Yeah, I can go to WM and drop $50 and have a new one (or go somewhere else and maybe get a better one!), but it bugs me that I have this thing I thought was my backup in case of car non-start, and it's not at the point I want to throw it away (because it works fine for launches!), but it's bugging me that there's something wrong and the tinkerer in me wants to mess around.

Before tilting at this particular windmill I figured it would be good to get insights from folks more familiar with these things.

Thanks.

Marc
 
It would be a sad day for me if I ever threw anything out that didn't work without 'rocket surgery'. Heck-it's worth 50 bucks just to see how good your third world counterpart did his/her soldering! I say open the hood and dive in. Worse case scenario-you have a launch battery with an expensive handle. FWIW- most of these have a motorcycle or kiddie car battery and a caseless charging system. The really crappy ones have an air compressor, work light, AM/FM cassette player and snow cone machine inside. Yeah- I've opened a few...
 
Yeah I should open it up and see what I find... it might just be a bad solder joint. I've assumed that perhaps there's some sort of fuse in there although I guess it would be a very high amp uncommon ( for a consumer) fuse that I wouldn't have a replacement for. This unit doesn't have a snow cone maker but it does have accessory port, work light and a USB charger. I avoided the version with the crappy air pump. When I get time I'll open this thing up and see what's inside. If anybody else has opened one of these up and has any hints feel free to chime in. Thanks
 
My guess wound be a solenoid or a relay, probably a cheap one activated by the switch. I'm like Dave, I can't throw something out, without opening it up and troubleshooting it. You have a meter, jump in!
 
If it worked once it should work again. Just check the solder joint and continuity through the positive cable. In the ones I have used once you jump start a car with them, that is about the end of them. YMMV. That also was with the first ones that came out! Good luck!
 
No. I'll guess it's working fine, but has a dead battery sensor across the cables so it won't jump a dead flat battery. You are not supposed to charge a frozen battery, if you do it can go KABOOM, so many smart chargers won't charge unless the battery reads some voltage value, probable 8 or 9 volts. Use the power port for DC power.
 
Thanks for the insights on this. I will open it up this weekend and see where I lose continuity on the positive cable, working backward from the battery clip.

I've thought it over and I now remember, I used it once successfully on my wife's car (lights drained battery) a month or three after buying it, but about six or eight months after that, I tried using it again when the battery on my own car failed (dead cell in the battery). This second time, the jump pack didn't help at all... maybe it died during that attempt or failed in the process of starting my wife's car before. When the cell in my battery died, I BARELY got my car started after using my wife's car to jump it. I was unaware it was a bad cell at the time. Took it to the chain where I bought it; they did tests and gave me a free replacement battery.

Anyway, since most of my use of the jump pack is for rockets, I just now noticed the jump pack had issues. LEt's see what I can find!

Marc
 
"Screwdriver...hemostat.....ohmmeter...sponge...suction....soldering iron...nurse-more light!...quickly, the storm is approaching.....*crackle* flash*pop*....IT'S ALIVE!!! " <cue organ music>
 
On my jump pack, there are two copper plates on each clip. However only one is actually connected to the lead into the pack. Before opening it up, it would be worth double checking.

Oh, and be a little careful around that bitty once the plastic is off.

Take pictures, I want to see what's in one of these things.

Kevin
 
On my jump pack, there are two copper plates on each clip. However only one is actually connected to the lead into the pack. Before opening it up, it would be worth double checking.
Kevin

DING DING!

OK, I feel so stupid. After reading this, I checked the clips and found that the spring in them that I thought was providing conductivity to the opposite side of the clip is just a spring, with no electrical connectivity.

After paying attention to where the juice is actually running, I get good current from the appropriate clip side pairs. So, I can't explain the trouble we had at the club launch some time ago, but this thing has the juice at the clips. Thanks Kevin, and all who participated!

Marc
 
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