[time-nuts] HP 5065A battery pack

Poul-Henning Kamp phk at phk.freebsd.dk
Sat Nov 21 09:22:29 EST 2015

In message <5650469B.1040106 at rubidium.dyndns.org>, Magnus Danielson writes:

>Lacking the charging controller in mine, what would be a good approach 
>to go about and build one?

A Mascot lead-acid charger and two VRLAs :-)

>Need to replace the battery setup in my XSRM setup too, the packs I 
>installed is now dead.

Really... You should build a Lab-wide 24V battery-backed DC supply instead.

>Tempted to think in terms of LiFePO.

Lithium is a bad choice for standby applications.

Normally we overcharge lithium batteries to get max capacity, but that
is also what kills them short of 1000 cycles.  If you leave them in the
charger "forever" they die "a lot sooner than forever".

When used in standby applications you can only use 70-80% of their
capacity because you have to stay out of the "overcharge" domain.

Unless it is kit which you lug around, VRLA is the way to go for standby.

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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