iamdarkyoshi's HIGHLY DANGEROUS (but extremely simple) Powerbank Capacity Tester

[iamdarkyoshi]

I need something for testing the capacity of powerbanks. Can't be bothered to buy a cheap tester.

 

So I made this device:

 

It has a relay that self latches when the two brown wires are touched, and once the voltage dips below about 4v, the relay will turn off and disconnect the load. This will detect when the battery bank decides that the battery is too low to output anything, and due to the fact that for it has to be manually reset with the two brown wires, it is especially good for powerbanks that tend to turn back on once their battery voltage floats up a little.

 

Here is the load:

 

Five 1 ohm resisistors in series with a fan on them. I have hand picked (or rather lucked out) 5 resistors that in series, pull exactly 1A at 5v.

 

 

So what makes this device so dangerous? What is the second relay used for? Why are there green and yellow wirew coming off the breadboard?

 

Glad you asked.

 

The second relay's coil is connected where the load is, so when the load turns off, so does this relay. This relay's contacts go off to...

 

 

... A mains powered lamp timer. The second relay is connected to a timeswitch. I figure that you could set the dial for midnight, and once the powerbank switches off, whatever the timer reads in hours ahead of the original midnight position is the battery bank's true capacity in amp hours (as we drew 1A, and the timer gives us the hours it ran for)

 

Now, this results in what I would consider the "true" amp-hour rating, as a 10Ah battery bank contains 10Ahs worth of lithium batteries, which on their own, do not put out 5v. They need to be stepped up in voltage, which means that a constant 1A 5v load, I will draw more than 1A from the batteries. 

 

I don't expect particularly great acuracy with this thing, but its a hell of a lot better than just trusting the ebay listing or my secondhand lithium cells.

 

Anyway, I hot snotted the wires in place so they don't easily fall out, and I ain't running this deathtrap tonight. Anyway, hope you guys found this idea at least somewhat entertaining, tomorrow I will test it!

[vanished]

Interesting invention.  What do you think Dave would say though?

[iamdarkyoshi]

2 minutes ago, Ryan_Vickers said:

Interesting invention.  What do you think Dave would say though?

You did whaa?

 

WITH WHAA?

[vanished]

Just now, iamdarkyoshi said:

You did whaa?

 

WITH WHAA?

I feel like this could be designed to not need mains power... I mean, correct me if I'm wrong but aren't you using that just to run the lamp timer?   There are lower voltage timers I'm pretty sure

[iamdarkyoshi]

1 minute ago, Ryan_Vickers said:

I feel like this could be designed to not need mains power... I mean, correct me if I'm wrong but aren't you using that just to run the lamp timer?   There are lower voltage timers I'm pretty sure

Certainly.

 

But I don't own any

 

I plan to eventually fix my constant current load (which can do upwards of 25A) and use that with an arduino. But this was a late night invention. Its midnignt here.

 

And since when were you a moderator?

[vanished]

1 minute ago, iamdarkyoshi said:

Certainly.

 

But I don't own any

 

I plan to eventually fix my constant current load (which can do upwards of 25A) and use that with an arduino. But this was a late night invention. Its midnignt here.

 

And since when were you a moderator?

since yesterday

 

Yeah I don't know if I would trust this to just run tests in the night... I hear your sense of smell doesn't work while sleeping and I want to know when it starts smoking  

[iamdarkyoshi]

1 minute ago, Ryan_Vickers said:

since yesterday

 

Yeah I don't know if I would trust this to just run tests in the night... I hear your sense of smell doesn't work while sleeping and I want to know when it starts smoking  

Random explosions and magic smoke aren't my main concerns.

Also that it totally an upcoming profile pic

[W-L]

Well let me just go grab the fire extinguishing...  

[vanished]

2 minutes ago, W-L said:

Well let me just go grab the fire extinguishing...  

ah, we joke but in all honesty this thing is probably just fine

[comicsansms]

15 minutes ago, Ryan_Vickers said:

since yesterday

 

Yeah I don't know if I would trust this to just run tests in the night... I hear your sense of smell doesn't work while sleeping and I want to know when it starts smoking  

You haven't been on the forum since 2013 and you are a mod!?!?!

[iamdarkyoshi]

2 minutes ago, Comic_Sans_MS said:

You haven't been on the forum since 2013 and you are a mod!?!?!

RYANATI CONFIRMED

 

Seriously like every mod so far has been from 2013

 

But yeah, it is probably safer than a lot of stuff being shipped from china

 

[vanished]

5 minutes ago, Comic_Sans_MS said:

You haven't been on the forum since 2013 and you are a mod!?!?!

I mean, have you seen the number of chinese spam threads lately?  We need a whole department for that shit...

[iamdarkyoshi]

7 minutes ago, Ryan_Vickers said:

I mean, have you seen the number of chinese spam threads lately?  We need a whole department for that shit...

They are highly entertainly when translated to chinglish though...

[vanished]

1 minute ago, iamdarkyoshi said:

They are highly entertainly when translated to chinglish though...

huh, I've never tried ...

 

Swinging this thread back around, do you think you might license this to the LTT crew for testing more power banks in the future?

[iamdarkyoshi]

5 minutes ago, Ryan_Vickers said:

huh, I've never tried ...

 

Swinging this thread back around, do you think you might license this to the LTT crew for testing more power banks in the future?

Nah, I would overengineer some sort of 3D printed thing, have it not work, go back to the bare basics, get ticked off and start at the very beginning, obligatory soldering iron burn, and then maybe I would end up with some sort of fabricobbled solution that works. Still need to see why my USB bananas can only do 50% of my phone battery...

[vanished]

1 minute ago, iamdarkyoshi said:

Nah, I would overengineer some sort of 3D printed thing, have it not work, go back to the bare basics, get ticked off and start at the very beginning, obligatory soldering iron burn, and then maybe I would end up with some sort of fabricobbled solution that works. Still need to see why my USB bananas can only do 50% of my phone battery...

Quote of the year  

At any rate, I liked the test they did and it's obviously sparked some further interest, so I hope they'll keep refreshing their test when necessary... and you never know, dangerous or not, if this works well, I'd call it a good design

[The Cool n00B]

I'm trying to figure out if there's ever a time that you're not making something

[iamdarkyoshi]

8 hours ago, Ryan_Vickers said:

Quote of the year  

At any rate, I liked the test they did and it's obviously sparked some further interest, so I hope they'll keep refreshing their test when necessary... and you never know, dangerous or not, if this works well, I'd call it a good design

Did you see my member title? I own four of these things lol

[vanished]

1 hour ago, iamdarkyoshi said:

Did you see my member title? I own four of these things lol

I did see it and figured it might be something like this... why tho?

[iamdarkyoshi]

30 minutes ago, Ryan_Vickers said:

I did see it and figured it might be something like this... why tho?

I'm not entirely sure. Maybe its because they were cheap? 1.33USD?

[vanished]

1 minute ago, iamdarkyoshi said:

I'm not entirely sure. Maybe its because they were cheap? 1.33USD?

you should take one apart then.. I bet it's atrocious.

[iamdarkyoshi]

1 hour ago, Ryan_Vickers said:

you should take one apart then.. I bet it's atrocious.

They are actually very good. They don't come with batteries, and so I sourced some cells from laptop batteries in the recycling bin. Just need to weed out the bad ones

[vanished]

6 minutes ago, iamdarkyoshi said:

They are actually very good. They don't come with batteries, and so I sourced some cells from laptop batteries in the recycling bin. Just need to weed out the bad ones

really?  I would have expected bare minimum quality components, bad construction and worse design   Take for example a charger I once had (and it was even a decent name): It plugged into the car's 12v plug and produced about 3.5 or something like that for running a GBA.  Once its usefulness had expired, I took it apart, hoping to change its output voltage and splice on a different cable so I could charge USB things with it.  It was a textbook voltage regulator so that was no problem, but there was 1 horrible design flaw - they had run both grounds separately, each to one of the contacts on the 12 v system.  Now, the issue with this is that had they joined them, and it lost connection, it would just shut off, but the way they had it, if one had broken but not the other, it would have stayed on but essentially disabled the voltage regulator letting close to the full 12 v (minus whatever the threshold is on a LM317T) run into the device!  Unbelievable!

[You_are_a_cunt]

I'm going to mail you one of my fire extinguishers, just in case

[Huntsman]

I like the gif of Dave banging his head on mic

 

On 5/28/2016 at 3:31 PM, Ryan_Vickers said:

huh, I've never tried ...

 

Swinging this thread back around, do you think you might license this to the LTT crew for testing more power banks in the future?

I think they might fare better with some variation of Dave's electronic load. In the process of making one with more features.