Author Topic: EEVblog #774 - Low Battery Discharge Testing Part 1  (Read 21790 times)

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Offline sakujo7

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Re: EEVblog #774 - Low Battery Discharge Testing Part 1
« Reply #50 on: August 07, 2015, 01:19:09 am »
To interface the BK e-load, I use a software uart on pins D7(Rx) and D8 (Tx), it can be moved on any available pins on the Arduino board (except D0 an D1 used for the uart-to-USB interface).

You probably want to put a level shifter between the arduino and the RS232 port. RS232 signal levels can be as high as +-15V (and inputs are supposed to tolerate +-25V), though many devices are lazy and only drive +-5V. Even that is bad for a board expecting 0 to +3.3 or +5V.
 

Offline manu

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Re: EEVblog #774 - Low Battery Discharge Testing Part 1
« Reply #51 on: August 07, 2015, 06:08:02 am »
Despite it is a db9 connector, BK decided to have a TTL UART interface (*not* RS232) => no need of level shifters nor to invert the signals.
« Last Edit: August 07, 2015, 07:50:03 am by manu »
 

Offline sakujo7

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Re: EEVblog #774 - Low Battery Discharge Testing Part 1
« Reply #52 on: August 07, 2015, 09:53:22 am »
Despite it is a db9 connector, BK decided to have a TTL UART interface (*not* RS232) => no need of level shifters nor to invert the signals.

Huh. Disregard my comment then! I should have RTFM.

You know, I spent 30 seconds staring at those pictures wondering just why it worked, and it never occurred to me that someone would actually put a TTL UART on a DB9.

I hope they have good protection on those pins.
 

Offline manu

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Re: EEVblog #774 - Low Battery Discharge Testing Part 1
« Reply #53 on: August 07, 2015, 11:56:46 am »
I hope they have good protection on those pins.

It's a shame, but I think not. I suspect them to want to make a little more money with their dedicated isolated cables.
 

Offline classical

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Re: EEVblog #774 - Low Battery Discharge Testing Part 1
« Reply #54 on: August 10, 2015, 02:01:48 am »
lygte-info.dk just published some values for 1W, 0.5W, 0.2W, 0.1W, 0.05W
http://lygte-info.dk/info/batteryEnergyAtLowVoltage%20UK.html
 

Online NANDBlog

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Re: EEVblog #774 - Low Battery Discharge Testing Part 1
« Reply #55 on: August 10, 2015, 06:38:32 am »
I hope they have good protection on those pins.

It's a shame, but I think not. I suspect them to want to make a little more money with their dedicated isolated cables.
Woooaw. This is unbelievable. Did they really do that? How much does a MAX232 cost? Like 40 cents?
Someone wasn't at their right mind making this decision!
 

Offline manu

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Re: EEVblog #774 - Low Battery Discharge Testing Part 1
« Reply #56 on: August 10, 2015, 06:53:21 am »
Woooaw. This is unbelievable. Did they really do that? How much does a MAX232 cost? Like 40 cents?
Someone wasn't at their right mind making this decision!

They didn't save the cost of a max232, they prefer sell a communication cable at 68€ at Digikey...
 

Online NANDBlog

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Re: EEVblog #774 - Low Battery Discharge Testing Part 1
« Reply #57 on: August 10, 2015, 08:51:54 am »
Woooaw. This is unbelievable. Did they really do that? How much does a MAX232 cost? Like 40 cents?
Someone wasn't at their right mind making this decision!

They didn't save the cost of a max232, they prefer sell a communication cable at 68€ at Digikey...
Custom communication protocols and cables are while not good practice, they are fine. I mean use it if you really want to have it. But dont use the standard serial connector, especially when you connect it to an industry standard it breaks it.
That is like having an IEC power input:

And write in the manual that this is for the 12V DC.
 

Offline manu

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Re: EEVblog #774 - Low Battery Discharge Testing Part 1
« Reply #58 on: August 10, 2015, 11:56:34 am »
Custom communication protocols and cables are while not good practice, they are fine. I mean use it if you really want to have it.
You are totally right, I can't blame a company to make some money with spare parts.

But dont use the standard serial connector, especially when you connect it to an industry standard it breaks it.
Well, I've seen so many things on a DB9 that I take nothing for granted until I RTFM.
 

Offline manu

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Re: EEVblog #774 - Low Battery Discharge Testing Part 1
« Reply #59 on: August 10, 2015, 12:07:02 pm »
I made a simple arduino interface to BK Precision e-load. I own a 8510, hopefully it will work for the complete 85xx serie (8500, 8502, 8510, 8512, 8514, 8518, 8520, 8522, 8524 & 8526)
It simply outputs the display values (voltage in mV, current in 0.1mA, power in mW) in plain ascii. (cf. Arduino source in bk85xx.zip)
You can log data on a PC with a Hyperterminal-like software (e.g. https://sites.google.com/site/terminalbpp/) and save the data to a .csv file.
I've added a Xbee (Serie2) on the arduino board to make it wireless.
I have a Xstick dongle on the PC-side but another Xbee (with its USB adapter) would be fine.
 

Offline RogerRowland

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Re: EEVblog #774 - Low Battery Discharge Testing Part 1
« Reply #60 on: September 24, 2015, 04:50:40 am »
So, what happened in the long term test?

Or is it still running?

Or did I miss it?

 

Offline EEVblog

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Re: EEVblog #774 - Low Battery Discharge Testing Part 1
« Reply #61 on: September 24, 2015, 05:42:04 am »
My meter doesn't have the option to log for more than 7 days!
New datalogger method required.
I have data for 50mW, 20mW, and 10mW.
 

Offline adprom

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Re: EEVblog #774 - Low Battery Discharge Testing Part 1
« Reply #62 on: September 24, 2015, 06:46:11 am »
This is a bit OT, but Dave, do you know where you got your soundproofing panels from? I am looking for pretty much the same ones.
 

Offline rs20

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Re: EEVblog #774 - Low Battery Discharge Testing Part 1
« Reply #63 on: September 24, 2015, 06:57:18 am »
This is a bit OT, but Dave, do you know where you got your soundproofing panels from? I am looking for pretty much the same ones.

Maybe not the same panels, but:

 

Offline adprom

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Re: EEVblog #774 - Low Battery Discharge Testing Part 1
« Reply #64 on: September 24, 2015, 07:11:36 am »
Yes I have seen that - I am looking for the maroon and charcoal ones. I have seen them on ebay - but not sure if they are the same panels.

As I am in Aus - wondering if Dave had a local supplier ;)
 

Online Fungus

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Re: EEVblog #774 - Low Battery Discharge Testing Part 1
« Reply #65 on: September 24, 2015, 07:55:29 am »
This is a bit OT, but Dave, do you know where you got your soundproofing panels from? I am looking for pretty much the same ones.

Technically they're for sound conditioning, not sound proofing.
 

Offline adprom

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Re: EEVblog #774 - Low Battery Discharge Testing Part 1
« Reply #66 on: September 24, 2015, 09:57:54 am »
This is a bit OT, but Dave, do you know where you got your soundproofing panels from? I am looking for pretty much the same ones.

Technically they're for sound conditioning, not sound proofing.

I wrote the post quickly - I should have called them 'acoustic panels' if we are going to be entirely pedantic ;)
 


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