John there seem to be various LI technology in Ham Radio for remote ops.
But they seem expensive from what I have looked at. Then a bit more of a
challenge stacking batteries for 24 V.
Possiblity, just get two AGM batteries in the 25A class and use what you
have.
Understanding the last comment is totally boring.
Regards
Paul
WB8TSL

On Sun, May 26, 2024 at 3:35 PM John Ackermann N8UR via time-nuts <
time-nuts@lists.febo.com> wrote:

Hi John,

So, I have used three pairs of 12V batteries that have been charged
similarly. That has worked out very well. I was now given another 10
batteries that I've similarly charged up individually and will wire up
so that they can form another 5 pairs.

Now, I know people that use LiFePo4. They have a few key learnings for
their use:

1. Use only appropriate chargers. They are more tricky on that.

2. Be carefull to cut off so they do not discharge too much (also valid
   for lead batteries)

3. Yes, the initial cost is higher, but treat them right and they
   survive better than lead, so total economy can be better.

Since I have been given lead batteries, I've stayed with that and use
it. If I had to invest from scratch, LiFePo4 looks interesting.

Cheers,
Magnus

On 2024-05-26 16:39, John Ackermann N8UR via time-nuts wrote:

For charging LiFePO4 batteries, these are reasonably compatible with
lead acid chargers with the following caveats

1. Lifepo4 have approx zero temperature coefficient, so any temperature
   compensation on the lead acid charger, if present needs to be disabled.
   (if is a good lead acid charger, it will have compensation and a
   temperature probe)

2. Equalise mode on the lead acid charger , if present must be disabled.
   Equalise mode  is designed to deliberately overcharge the battery to
   being all cells to max. This will dramically overcharge the LIFEPO4
   cells. no good.

3. Low battery cutoff, like on a lead acid, is essential. Set for 2.7V
   per cell. LIFEPO4 cells if discharged below 2.7V per cell say all the
   way to 2.5,  must have initial charge rate of less than C/50 ideally
   until they reach 2.7/cell.

LIFEPO4 batteries, due to their all-off -capacity performance, will
provide approximately 2x the effective useable capacity of a lead acid
cell, especially at something like 0.333C discharge (3 hours). Most lead
acid batteries are specified for 10 or 20 hour discharge rates .  
overall you are a factor of 4 ahead of weight !.

Now- time has marched on, and many modern chargers either have
microprocessor contrained LIFEPO4 profiles or chips that know what they
are doing, so finding a suitable charger is fairly straightforward. A
pro lead acid charger will be fine most likely, also- because on a pro
charger you would have control over options like temp comp and equalise
mode.

feel free to contact me direct

glen

On 27/05/2024 12:39 am, John Ackermann N8UR via time-nuts wrote:

John Ackermann N8UR via time-nuts writes:

LiOn is a weird battery chemistry:  Strictly speaking it is only a
~3.7V cell, but for strange reasons you can overcharge them to ~4.1V,
and get another 20% capacity, which is how nameplate capacity is
specified.

In theory you can float LiOn in the range 2.7V to 3.7V, but you
cannot trust the cells to balance themselves, you have to regulate
the voltage over each individual cell, and that complicates things.

But if you already have all the infrastructure and dont need a particular
long runtime:  Buy two new AGM batteries and spend your time and money
on something else.

--
Poul-Henning Kamp      | UNIX since Zilog Zeus 3.20
phk@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.

John,

I have found that the HLG series of Meanwell power supplies work quite well
in that service. The HLG-600H-30A is rated at 20 amps and is adjustable for
constant current/voltage. My 12v home system uses a HLG-600H-15A to
charge/maintain a 600 AH LiFePO4 bank, and I have used their lower powered
HLG supplies in several other LiFePO4 applications.
-Mike-
WA6ZTY

On Sun, May 26, 2024 at 12:35 PM John Ackermann N8UR via time-nuts <
time-nuts@lists.febo.com> wrote:

Hi

There are several outfits that do very good LiFePO4  chargers. One is Victron. Often the answer is a hybrid inverter/ charger. They aren’t cheap…..

Bob

Sent from my iPhone

Hi John

Probably a little overkill, but I have good experience with the Mini-Box
OpenUPS boards (the original, one not the OpenUPS2). It can be setup
with multiple cell chemistries, does balancing, has wide input/output
voltage, 6A (10A peak) output current, etc.. Only issue (beside cost) is
that it's switching, so maybe the added noise makes this a no-go.

BR, German

On 2024-05-26 11:39, John Ackermann N8UR via time-nuts wrote:

Good morning to the group. Since this thread started I have been reading
about the LiFePo4 batteries.
They really can be treated much more like a traditional 12V battery in some
respects. It seems they come with a battery management
system internally. Price is easily 3-4X typical batteries. Though honestly
PB batteries are all over the place in cost.
Very hard to compare.
There are youtube videos of LiFePo4 tear downs and those are really
interesting in the wide range of mechanical construction.
By looking at the specs you have no idea what you are buying. Well the same
goes for PB batteries....
John thanks for getting the mind working and relooking at the battery
technology.
Paul
WB8TSL

On Mon, May 27, 2024 at 11:07 AM Germán Herrera via time-nuts <
time-nuts@lists.febo.com> wrote: