David Delman via EV wrote:
Thanks for the ideas Jay. It really isn't practical for me to remove the
batteries and rewire them in parallel.
I was wondering if I could build a simple "trickle charger" for the
entire pack.
I envision an isolation transformer 120vac in and 120vac out. The output
connected to a full wave bridge rectifier with perhaps an incandescent
light bulb in series with the output to limit the current.
This would supply ~169.68 vac peak or just over 13v per cell. Provided
that the output of the transformer was really 120vac...
The question is, if I start out with balanced batteries will they stay
balanced while being trickle maintained in series...?
Dave
OnTue, 16 Apr 2019, Jay Summet wrote:
If this is a one-time park long term storage type situation, perhaps you
could remove the batteries (or at least, their terminals) and wire all
12 in parallel and then use a small float charger on the whole set at once?
Alternatively, what is the self discharge rate of AGM's vs the projected
length of storage? If it's just for a few months, you could possibly
just charge them up fully and then disconnect them and be ready to
recharge when you return.
Jay
On 4/16/19 2:39 PM, David Delman via EV wrote:
I am going to have to store my eLectric DeLorean at a facility away from
home.
The car has 13 Sears PM-1 lead acid AGM batteries.
Presently I use 13 individual chargers, one for each battery to keep
them charged and balanced. This won't be practical where I am going to
store the car.
What is the groups advice for keeping the batteries charged and balanced?
Hi Dave,
You definitely don't want a "trickle charger". This is the cheapest,
crappiest kind of charger. All it does it put a continuous current into
the batteries. This will slowly overcharge them to death!
For lead-acid, you want a "float" charger for long-term maintenance. It
holds a constants *voltage*, and lets the current fall to almost zero
when the battery is fully charged.
But a float charger isn't practical for a long string of cells (like
your 120v pack). The batteries certainly won't be balanced; so some will
get more voltage (and overcharge), while some will get less (and not
fully charge).
Also, float charging is what you do if you may need the batteries to be
ready and fully charged any time. For example, an alarm system or UPS
power supply where you may need it fully charged at any time.
If this is for short-term storage (a few months), just fully charge
them, and store the car as-is. AGMs can happily sit for many months
without charging.
Just make sure that there are *no parasitic loads* that are always-on
and connected! A clock, alarm system, keyless remote, or even your
individual battery chargers may draw power from the batteries when the
car is off! If you aren't sure, then disconnect the batteries before
storage.
If this is for long-term storage, then I'd recommend removing the
batteries. Either keep them in your garage and charge them occasionally;
or just sell them and buy replacements when the time comes.
The usual problem is that the batteries were good when the EV got
stored, but they never get charged and the storage lasts longer than you
thought; and the batteries all die.
--
Fools ignore complexity. Pragmatists suffer it. The wise avoid it.
Geniuses remove it. -- Alan Perlis, "Epigrams on Programming"
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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