HELP IDENTIFY POSSIBLE COMPONENT FAILURE

Thread Starter

Stingray230sx

Joined Jul 19, 2022
4
HELLO, and thanks for the add to the community.
I have a harbor freight jump box that is kept plugged in to assure it's charged when needed.
a while back one of my cats managed to unplug it and I took the back off and verified it was still charging and it charged back up just fine.
Fast forward to yesterday and even though the jump box was plugged in, it was not charged enough to work.
I thought maybe it had been knocked loose so I put t on the counter plugged in, and grabbed another one I had found while cleaning out my parents house [had to replace it's battery since it sat unplugged so long]
when I came home the box was still dead, so apart it came, with the battery only reading 5V.
I pulled it out and then grabbed the meter and verified it was NOT charging to the output wiring to the battery.
traced the power supplies wiring to the tiny circuit board and it is putting out 17V and there is a small relay [blue] that "clicks" when the wall plug is attached.
however there is no 12V output .
attached is a pic of the small circuit board, there does not appear to be any damaged components so I was wondering if anyone was familiar with this style of circuit and could offer insight as to which component might have gone bad, as I really hate to just throw it away

thanks for any advice

doug
 

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Thread Starter

Stingray230sx

Joined Jul 19, 2022
4
Ok, on further exam
Welcome to AAC!

For starters (pun), what is the model number or a picture or link to the unit?
Thanks,
it is a bit older, so i couldn't find it on the Harbor Freight website, here is a pic of it and the only numbers on the back of it.
And I am sitting here waiting on a buddy to pick me up, helping set up another friends 454 Donzi engine on a dyno this morning.
while I am looking at it, the "power supply" is simply a wall charger with the end cut off and the two leads soldered to the board.
Pulling it's bracket off to read it's data sticker its output is "supposed" to be 12V-500ma.
now my circuit days as a biomed and sterilizer tech took me out of troubleshooting on the board level to just determining fault and swapping boards, hence my asking on here.
Maybe the 17V from the power supply is taking down the output?
 

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Thread Starter

Stingray230sx

Joined Jul 19, 2022
4
If the batteries have not been charged for a few years then they are very likely dead from sulfation.
yes, I agree, however this has been plugged in all this time , used probably 6 months ago and returned to the wall plug in.
But I did put the battery on my NOCO Genius charger and it is not happy, so it must have failed a while back and has been sitting plugged in the wall, but not charging
 

MrChips

Joined Oct 2, 2009
26,790
I can suggest two things if you have not done so already (which I believe you have).

Try charging the batteries separately on another charger.
With the batteries not connected, measure the voltage output at the charger circuit.
 

Thread Starter

Stingray230sx

Joined Jul 19, 2022
4
I can suggest two things if you have not done so already (which I believe you have).

Try charging the batteries separately on another charger.
With the batteries not connected, measure the voltage output at the charger circuit.
sorry, been out most of the day
yea, I have done both of those.
the circuit board has the output to the battery terminals so I connected the meter directly to those, and get 0V.
and my NOCO Genius charger is getting nowhere with the battery itself.
was 5V when i realized the jump box wasn't working, and the NOCO Genius charger faults after a couple hours trying to charge it.
measured the battery after the the NOCO faulted for the second time, it got it up to 8V but Im guessing this one is going to the recycler.
since the jump box circuit is dead, i will just scrap it as a new battery is $35 and a complete new jump box can be had for $60.
If the jump box was charging, then a new battery would be worth it, but it probably killed the battery by failing to charge and this is one of those plug it in till you need it deals
saved my butt a lot though, as I have a boat with exhaust cutout solenoids which if left "on" after hauling out, will drain the battery quickly.
the marina that rack stored it would invariably put it in the water for me, then leave the switch "on" so I got in the habit of taking the jump box with me every friday night because it was dead 90% of the time after I got there.,
 
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