"mike" wrote in message
news
On 5/22/2017 9:34 AM, Jim Wilkins wrote:
...
A computer controlled dual-output power supply is a useful tool.
Use one output to charge the battery and read back the voltage.
Use the other output to drive a voltage to current converter for the
load.
Makes it very easy to control and log and graph and...


What happens to the expensive power supply if the AC power fails while
the battery is connected, or you accidentally connect the battery
backwards???
http://www.keysight.com/main/editori...03725:epsg:faq
"Active loads that create a sinking current should not be connected to
a power supply."

I've been charging batteries through series diodes, using this meter
to monitor the voltage beyond the diode drop:
https://www.amazon.com/DROK-Digital-.../dp/B015R3PMFC
"With reverse polarity protection to avoid burning out"
A spare LM78xx from your junk collection can extend their supply
voltage rating above the input limit, an LM7824 increases it the
highest.

The one I tested the other night matched a 5-1/2 digit Fluke to 1 mV
at 10V in. Notice where it was made.

The output protection I've been adding to my homebrew battery charging
variable power supplies is a forward diode to block a meter-busting
surge back into the 0.2 Farad output cap and a reverse-biased diode to
ground that -should- pop the output fuse or breaker if a battery is
connected backwards. The problem with testing breakers is that they
have a maximum interrupting rating above which they may work only
once, and of course with fuses is that you know they -did- work and
hope the next one (from a different source?) is the same.
-jsw