how 'bout them lipo buzzers.

Farfle

Farfle

100 kW
Joined
Jun 27, 2010
Messages
1,759
Location
Redmond OR
Hey all, a friend of mine (bartimaeus here on the forums) showed me one of these little gadgets available from several retailers on the web. for those not familiar is has an lcd display that displays the cell voltages (Very accurate!!!) one after another followed by the total pack voltage up to 8s, and two farking earsplittingly loud beepers on them. (pretty sure these are smoke detector grade beepers). Anywho, they have one feature that i am particularly interested in, a programmable cell-level LV alarm. there is a little button on the back that adjusts the rape alarm in .1v increments between 2.7 and 3.8v. so, obviously it draws some power, that I don't mind, but does it draw it evenly? and how accurate is it?

Here's the test candidate:

http://www.amazon.com/Integy-C23212-Voltage-Checker-Warning/dp/B003Y6E6IE/ref=sr_1_1?ie=UTF8&qid=1359596957&sr=8-1&keywords=integy+lipo+buzzer

And the test equipment:

20130130_164406.jpg


be back with results in a bit.
 
Turns out that the voltages are very accurate. I have a slightly imbalanced 6s zippy pack to test with and its pretty much spot on.

"Integy" brand 12 dollar buzzer:

V1-3.20
V2-3.53
V3-3.47
V4-3.55
V5-3.47
V6-3.51
V total- 20.7

Fluke 289, factory calibrated 11/14/2011

V1-3.1942
V2-3.5290
V3-3.4819
V4-3.5552
V5-3.4779
V6-3.5186
Vtotal- 20.750
 
I took some graphs of ma / time and they are interesting, It seems to fluctuate quite a bit as the buzzer translates through different phases of measurement. But it turns out that I need to buy a special IR data cable for this meter, so detailed graphs are going to have to wait. Here are some screenshots instead:

*EDIT* pictures were huge, so heres two. you can manually cut and paste to see the rest:

Cell six
20130130_182545.jpg

20130130_182551.jpg


Code: 
Cell five
[img]http://i1019.photobucket.com/albums/af318/sirfarfle/20130130_182607.jpg[/img]
[img]http://i1019.photobucket.com/albums/af318/sirfarfle/20130130_182614.jpg[/img]

Cell four
[img]http://i1019.photobucket.com/albums/af318/sirfarfle/20130130_182633.jpg[/img]
[img]http://i1019.photobucket.com/albums/af318/sirfarfle/20130130_182637.jpg[/img]

Cell three
[img]http://i1019.photobucket.com/albums/af318/sirfarfle/20130130_182644.jpg[/img]
[img]http://i1019.photobucket.com/albums/af318/sirfarfle/20130130_182648.jpg[/img]

Cell two
[img]http://i1019.photobucket.com/albums/af318/sirfarfle/20130130_182700.jpg[/img]
[img]http://i1019.photobucket.com/albums/af318/sirfarfle/20130130_182705.jpg[/img]

Cell one
[img]http://i1019.photobucket.com/albums/af318/sirfarfle/20130130_182713.jpg[/img]
[img]http://i1019.photobucket.com/albums/af318/sirfarfle/20130130_182720.jpg[/img]

Ground wire (this is total draw, technically backwards)
[img]http://i1019.photobucket.com/albums/af318/sirfarfle/20130130_182728.jpg[/img]
[img]http://i1019.photobucket.com/albums/af318/sirfarfle/20130130_182734.jpg[/img]
 
Looks like the peak current when the buzzer is going off is around .091A on a 50% duty cycle.

the data from the massive pile o o pictures up there is this:

Average current draw per cell in ma:

A1: 1.265
A2: 1.023
A3: .744
A4: .616
A5: 21.530
A6: .041
A total: -23.981
 
I like it. Cell level warning, and I particularly like the adjustability. You could set em for say 3.6 or 3.7v, and get a warning when it's that low under load for an early stop. But if you need it all to get home, you could adjust them down, and just be sure you don't go below 3v as you limp home on 100w.

The cheaper beepers I've used, you'd have to listen to them beep all the way home, and never know how far below 3.5v you were getting. Like the cheap beepers though, a bit of a pita to plug and unplug all the time. Well worth the effort if you are doing more than 80% dod discharges.
 
Amazon had a similar looking unit for $2 less: http://www.amazon.com/gp/product/B005HG5B5G/ref=oh_details_o00_s00_i00
 
I use these on my bicycle with 4 x 5S LiPo Zippys. I don't find 'm that accurate (maybe it depends on the
manufacturer) but other than that, I'm happy with them. I run the Lipo without BMS, these buzzers
are the only low-voltage protection I have. On my bike they're set to go off at 3.6V.
They are cheap enough to double-sided-tape them to the 5S bricks, one for each brick.
 
So, some good news, if you disconect the most negative wire. The drains are these:


A1: 1.165
A2: 1.075
A3: .643
A4: .501
A5: .041
A6: .041
A total: 3.469
 
You need one of my even drain boards :) Perfectly even drain across all cells for cell-logs, and these things now too.
 
I could be persuaded to, they are easy to make and very small. :)
 
Haha... I hate to persuade people into making and selling things, knowing perfectly well how little money can be made if any at all. I've skimmed through the thread about cell log modification, I just hate soldering tiny parts.
 
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