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Michael Diehr wrote:
> Lead acids do vent nasty stuff - hydrogen gas (explosive) and sulfuric
> acid vapor (toxic, corrosive).? Ventilation is required.
>
> Have you considered upgrading to a Lithium battery? ? They are much more
> expensive in initial purchase, and can't be charged at temperatures
> below freezing, but on pretty much every other metric they are vastly
> superior to lead acid batteries and will probably outlive the van. ? One
> Lithium battery will outperform two lead acids, and they don't require
> any ventilation, etc.

Time for my battery rant. :-)

In the best-case scenario, lithiums can be pretty good. But frankly,
that's true for lead-acids as well.

Energy storage:

Lithiums have about twice the energy storage per pound as lead-acids.
But they occupy about the same physical space for the same energy
storage. So a 12v 100ah battery is about the same size, whether lithium
or lead-acid... the lead-acid just weighs more.

Safety:

Lithium batteries BURN! The failure modes in lithium batteries can
easily start a fire; and it's the type of fire that can be very
difficult to extinguish. Keep in mind; you are going to use the battery
until it fails. And one of a lithium's failure modes is a fire!

Lead-acids don't burn. They might leak acid or vent hydrogen; but they
won't start a fire except in the most extreme scenarios. If you're
worried about venting or hydrogen, use a sealed AGM type lead-acid.

Life:

The main problem is that people buy mostly on price. Consumer-grade
lead-acids *and* lithiums are only likely to last 3-6 years (no matter
what the ads claim). Think about the batteries in your laptop or phone;
they are lithium, and most of them get weak and fail within 3-6 years.

If you want a lead-acid battery to last, don't buy a 12v starting,
marine, or RV battery. They are short-life batteries. Buy a pair of 6v
golf cart batteries, or an industrial EV battery, or one for big
commercial UPS backup power supplies. These can last 10 years or more. I
have Deka gels and Enersys AGM batteries that are over 20 years old and
still have more than half their original capacity.

If you want a lithium to last, forget the mass-market "lead-acid
replacements" and Chinese ebay specials. Get a used electric vehicle
battery -- the EPA *requires* the manufacturers to warranty them for 10
years, so the quality is far better.

Abuse:

Most batteries don't die of old age -- they are *murdered* by negligence
and abuse. Bad chargers are everywhere (the Magnetek in the EV is a good
"bad" example). Running any battery dead is like giving it a heart
attack. Even if it survives, it's been damaged.

Marketing: It's said that there are liars, damned liars, and battery
salesman. Most people's understanding of batteries is so poor that they
fall victim to every kind of puffery and exaggeration. They don't test a
battery; they just blindly believe what the salesman and old wive's
tales say.

It's currently fashionable to claim that a lithium battery is
"equivalent" to a lead-acid. This is mostly a marketing lie. If you're
starting an ICE, all you need is a few seconds of high current. That
amounts to less than 1 amphour. Lithiums tend to be better for this type
of high-current pulse. So a tiny cheap low-capacity lithium can start an
car engine... once.

Car batteries have far higher amphour capacities -- not just to start
the engine; but also to maintain power for long periods of time. Modern
cars have dozens of always-on loads (clocks, radio presets, keyless
entry, security systems, electronic odometers, etc). Our Eurovans have
even more (CO detectors, etc.) So the batteries are sized to be able to
handle all these "vampire" loads for weeks on end, in case the vehicle
is not driven.

Lead-acids are *good* at providing small amounts of power for a long
time -- you get *more* than the rated amphour capacity when discharged
this way. A lead-acid "equvalent" battery can't power these loads.

"There are few industries with more BS than the battery industry." --
Elon Musk

"The storage battery is one of those peculiar things which appeals to
the imagination, and no more perfect thing could be desired by stock
swindlers. Just as soon as a man gets working on the secondary battery,
it brings out his latent capacity for lying." -- Thomas A. Edison

Grumpy old Lee Hart

--
Lee Hart, 814 8th Ave N, Sartell MN 56377,

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