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Battery and Charger Strategy - any ideas?

M

MooseFET

Jan 1, 1970
0
It's not actually very difficult. Microcontrolelrs typically have A-D converters on
board now. Add a serial EEprom for data backup and you're away.

The battery he is using can provide the backup power. You only need a
way to deal with the rare case of charging back up after the battery
was taken totally flat. If he is running a low power PIC of one of
the small TI processors, he can use a very sloppy and low power
regulator to keep it alive during the "off state".
 
Time for re-design that does not require any nternal battery.
Run your circuit from the battery under test. Charge up a
supercap from that battery if it needs memory between events.
You'll probably need to re-design for low current. If an
automotive battery can't provide enough power to drive your
circuit, it's shot anyway - no need to test further.

I like it! Actually, many low end testers do this. Once you add
stored results, printing, backlight, test from flat etc you do need a
battery.

Thank you all for creative and useful input.

I'll follow up microprocessor with coulomb counting, or voltage
controlled NiMH charging. LiPoly is still a posiblility, because of
its excellent voltage vs state of charge characteristics. Plus I will
check with management to see if we can hang on to lead-acid a while
longer.

Roger Lascelles
 
C

Chris Jones

Jan 1, 1970
0
I like it! Actually, many low end testers do this. Once you add
stored results, printing, backlight, test from flat etc you do need a
battery.

Thank you all for creative and useful input.

I'll follow up microprocessor with coulomb counting, or voltage
controlled NiMH charging. LiPoly is still a posiblility, because of
its excellent voltage vs state of charge characteristics. Plus I will
check with management to see if we can hang on to lead-acid a while
longer.

Roger Lascelles

I saw an article/advertisement in an electronics magazine
(electronicsweelky.com) about float charging Lithium cells:
http://www.electronicsweekly.com/Articles/2006/02/01/37528/Float+charging+lithium+ion+cells.htm

BTW, the failure mode I have seen in all the laptop batteries that I have
opened is open-circuit cells, so for reliable operation I would consider
multiple lithium cells in parallel (with whatever fuses etc. are needed to
make this safe).

Why are you designing out the SLA?

Chris
 
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