Today's Message Index:
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1. 05:03 AM - Re: bench power (bobnoffs)
2. 05:18 AM - Re: Poor Man's Battery Tester (user9253)
3. 05:38 AM - Re: Poor Man's Battery Tester (user9253)
4. 08:39 AM - Re: Poor Man's Battery Tester (Eric Page)
5. 08:48 AM - Re: Some Thoughts on Z101 (Eric Page)
6. 12:23 PM - R.e. Poor Man's Battery Tester (Steve Stearns)
7. 05:12 PM - Re: Poor Man's Battery Tester (Roger Evenson)
8. 05:34 PM - Re: Poor Man's Battery Tester (user9253)
9. 09:02 PM - Re: Poor Man's Battery Tester (Charles Davis)
Message 1
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while waiting for the power supply i ordered i came across some tutorials [u tube]
about taking an atx [the power supply in a computer] and converting it to
a bench power. easy, and a fun project.
i would take a guess that dell or H.P. or what ever computer mfgr.. has a power
supply of 'higher standards' than a $65 bench power on ebay.
anyway.........everyone has an old computer lying around and i will soon have
another bench power made from an atx . 12 volts, that's it, although there are
leads for 3.3 and 5.08 volts i have no need. at 12 amps it is plenty for me.
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http://forums.matronics.com/viewtopic.php?p=500469#500469
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| Subject: | Re: Poor Man's Battery Tester |
Bob's Poor Man's Battery Tester http://www.aeroelectric.com/articles/battest.pdf
is supposed to shut off automatically at 10 volts. Did you change any parts values?
Did you use a 10 volt zener?
--------
Joe Gores
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| Subject: | Re: Poor Man's Battery Tester |
Trouble shooting the battery tester:
Is the zener diode installed backwards?
If one end of the zener diode is disconnected, does the relay drop out?
If not, has the correct transistor been used?
Has the transistor been connected correctly?
--------
Joe Gores
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| Subject: | Re: Poor Man's Battery Tester |
It sounds like your circuit may be shutting off at the natural dropout voltage
of the relay, which suggests that full battery voltage is reaching the relay's
coil.
In addition to Joe's suggestions, check that the Zener diode is actually a 10V
device, and not something near 3V, and that it hasn't failed (diodes can fail
short circuit).
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=500472#500472
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| Subject: | Re: Some Thoughts on Z101 |
Ceengland wrote:
> Have you tested the 'dual' version for proper boost operation? The data sheet
hints that it is a buck converter; not boost.
It's buck-boost; note the two inductors. The LM2577 does boost and the LM2596
does buck.
https://www.ti.com/lit/ds/symlink/lm2577.pdf
https://www.ti.com/lit/ds/symlink/lm2596.pdf
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| Subject: | R.e. Poor Man's Battery Tester |
You said, "My experience has been that it turns off when the battery
reaches about 4V."
I built one and it shuts off right at 11 volts which is what I was
expecting. I think you have a wiring error or some other issue.
Steve.
Steve.
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| Subject: | Re: Poor Man's Battery Tester |
Bought new resistors and 10V zener. Rewired carefully on a test board. This
time it kicked off, but at a higher voltage than I wanted (12V).
The zener was a NTE5019A, 10.0V +/-5%, 1/2 watt. Isn't that more like
+/-20%? Cost all of $0.79.
I'll go back Monday, see if I can get a +/-1% zener, and ask about a higher
quality brand.
Thanks for your comments. One more question...does the wattage make a
difference in this circuit?
Roger.
On Fri, Jan 29, 2021, 9:23 PM Roger Evenson <revenson3@gmail.com> wrote:
> I built Bob's "Poor Man's Battery Capacity Tester".
>
> Somehow I got the impression the relay would 'drop' out and thus turn off
> the lamp and clock when the battery reached about 10V. But after
> re-reading "Battery Replacement: A Plan for Throwing in the Towel", that
> expectation is not written there. My experience has been that it turns
> off when the battery reaches about 4V.
>
> Odyssey Load Test Procedure and Reconditioning Procedures recommend ending
> the test at 10V. I've done this, but it requires my presence when the
> battery nears 10V.
>
> Is there a way to modify this circuit so that it will 'turn off' when the
> battery reaches 10V?
>
> Or, is there a commercially available tester that would load a battery at
> 4 amps and record the time required until the battery reaches 10V?
> Roger.
>
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| Subject: | Re: Poor Man's Battery Tester |
The problem is not the tolerance of the zener.
The resistors affect the dropout voltage too.
Try a 9 volt zener. They are cheap. Buy a few different values to experiment
with.
Wattage does not affect the circuit very much. 1/2 watt is good.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=500477#500477
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| Subject: | Re: Poor Man's Battery Tester |
You may have better luck getting 2x5v 1% zeners than a 10v 1% - just
wire them in series
Charles
On 31/01/21 03:10 am, Roger Evenson wrote:
> Bought new resistors and 10V zener. Rewired carefully on a test board.
> This time it kicked off, but at a higher voltage than I wanted (12V).
>
> The zener was a NTE5019A, 10.0V +/-5%, 1/2 watt. Isn't that more like
> +/-20%? Cost all of $0.79.
>
> I'll go back Monday, see if I can get a +/-1% zener, and ask about a
> higher quality brand.
>
> Thanks for your comments. One more question...does the wattage make a
> difference in this circuit?
> Roger.
>
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