[ausev] New EV Use

[Sarah & Erik]

A couple comments myself, and a hopefully correct answer. Happy New Year!

On Dec 29, 2007 1:33 PM, Chris Robison <chris at chrisrobison.org> wrote:
> Very good advice here. I'll add some comments (and a question):
>
snip
>
> > chronic overcharging - there's a point where more hard charging doesn't help
>
> This is one I'm not completely clear on; maybe someone can help out.
> It's been my impression that over-charging flooded batteries effectively
> just wastes energy and water and makes an unnecessary mess, and if the
> level is low it risks exposing the plates. I'm not sure if there's any
> other problem associated with keeping the batteries on charge too long.
>
/snip

Charging promotes the shedding of the active plate material which
falls and gathers at the bottom of the cell, which contributes to
shorter battery life. Definitely equalize and make sure your batteries
are fully charged before you worry about overcharging a flooded
battery, but there is a reason to care beyond energy and water waste,
AFAIK.

> > leaving them sit quite discharged for a while - basically, charge as
> > soon as you can. I don't believe this is quite as scary as most make
> > it out to be
>
> Here's the situation as I understand it. Lead acid batteries like to be
> full or as close to it as possible. Aging of a lead-acid battery is an
> unstoppable process, but the more full the battery is at any given
> moment, the slower it is aging.
>
/snip

Yes, but there's a worry that I didn't understand until I had
batteries to take care of, and it's that people always talk about
charging and not running them down and they'll last longer the longer
they charge. Yes to all of the above, but the electrochemist from US
Battery said it's not a big deal if they sit for an hour or several
discharged. Days is bad, but you don't need to run for the plug when
you get home. Charging sooner is always better, but he said basically,
there are bigger things to worry about besides charging the first
instant you can. That being said, charge as soon as you can =)

> Watering flooded lead acid batteries is a significant chore. There is a
> way to eliminate the hassle almost completely, although it's a very high
> one-time expense. There are "watering caps" that automatically fill the
> batteries to a specific level, and they also function to limit the
> amount of acid that escapes during charging. They are installed and
> connected with tubing in a daisy-chain fashion, to create a single
> connection for watering. You plug in, the water flows, they individually
> shut off as each cell gets full, and in seconds it finishes and you
> unplug the hose. We'll be offering this kind of system for approximately
> $16-17 per cap (one per cell). At that price it's a lot cheaper to do it
> yourself though, if you have the time. It may be a good choice for part
> of your pack if it's especially difficult to access for watering.
>
> I think an important point regarding all of this is that flooded lead
> acid batteries are the cheap way to go, but there is a price in terms of
> labor. More advanced batteries require an electronic battery management
> system (BMS). With flooded batteries, *you* are the BMS. You perform the
> function by doing occasional equalization charges, and replacing water.
>
>    --chris
>

There are single cell watering devices that you take from cell cap to
cell cap that automatically fill each to a prescribed level, but with
my water saver battery caps, I was concerned they would overfill the
batteries. These watering cans are about $15. More trouble than the
daisy chain, but it beats the pour-and-eyeball-it method.


Erik