in article , Avery Fineman at
wrote on 2/25/04 20:57:

In article , U
writes:

Where I live, in the woods of Maine, we have power outages.

Solar panels and all that stuff is quite expensive, but old car batteries
("old" is when it doesn't get my Diesel started in subzero temps) are not.

To make things just a bit comfi it would be nice to leave it in place with a
charger attached (right now I tote the charger around when needed).

Many things will run right off the batterie(s), others might need an
inverter.

So basically I am talking about a photovoltaic system without the
photovoltaic panels, sort off.


So which chargers can I leave permanently attached to a battery?

The word 'trickle charger' or 'shore power' comes to mind. How is that
different from my old Sears charger which does me good for many years
already (but I unhook it after a day at most!).

With good control of charging current and voltage, the battery can
"float" in the circuit, always connected to the charger or the AC mains
low voltage supply that can take over from the battery when mains are
hot. The space folks do that regularly from low earth orbit (90 min.) to
geo-synchronous (24 hours), using series power diode isolation.

Another thought is to check out computer UPSs which have already
been engineered and tested, ready to go off the shelf. Those can
handle up to 600 W loads for small servers and auto-switch to internal
batter in less than an AC cycle. Industrial-strength UPS models can
handle much more. A little, cheap UPS sits between my PC box and
line all the time now, can easily handle 300 W loads for several minutes.

Len Anderson
retired (from regular hours) electronic engineer person

Len,

You are right about the UPS, but the car batteries are already here as is
enough stuff to probably build a suitable charging supply with.

There is one thing which should not stop around here, I just found that out
the hard way, and that is the water pump for my hot water solar collectors
(she blows like a whale!).
But once I buy that rather expensive DC circulator pump (only 1.5 amps)
everything can run off that old battery.

I guess the only thing left to do is to find a little circuit which provides
that good control you mention so that that battery can really be left on the
charger for good (I hear people commenting that some charging circuits do
get confused when they are hooked up to a battery which in turn is providing
power to a load but I don't understand why that is).

regards Uwe

One thing to keep in mind is that battery voltage changes with
temperature, and any float or trickle charger that doesn't take this
into account can shorten a battery's life considerably. So if you want
to get the longest life from your battery, you should make sure the
charger is properly temperature compensated.

Roy Lewallen, W7EL

One thing to keep in mind is that battery voltage changes with
temperature, and any float or trickle charger that doesn't take this
into account can shorten a battery's life considerably. So if you want
to get the longest life from your battery, you should make sure the
charger is properly temperature compensated.

Roy Lewallen, W7EL

One thing to keep in mind is that battery voltage changes with
temperature, and any float or trickle charger that doesn't take this
into account can shorten a battery's life considerably. So if you want
to get the longest life from your battery, you should make sure the
charger is properly temperature compensated.
=======================================
Roy , If the lead acid battery charging current is limited to 0.1C ,(example
a 15Ah sealed battery is charged at max 13.8 V with a current not exceeding
1.5A) is temperature compensation then still a necessity to optimise the
battery's (usable) life ?
And if it is, in which temperature range ? I have not found this info
through Web based tutorials.
I am very interested in this topic since I charge a number of batteries
(some non- sealed some sealed) by means of a (150 W max)wind generator and
2 pcs 64Wpeak solar panel.

TIA for any advice

Frank GM0CSZ / KN6WH

One thing to keep in mind is that battery voltage changes with
temperature, and any float or trickle charger that doesn't take this
into account can shorten a battery's life considerably. So if you want
to get the longest life from your battery, you should make sure the
charger is properly temperature compensated.
=======================================
Roy , If the lead acid battery charging current is limited to 0.1C ,(example
a 15Ah sealed battery is charged at max 13.8 V with a current not exceeding
1.5A) is temperature compensation then still a necessity to optimise the
battery's (usable) life ?
And if it is, in which temperature range ? I have not found this info
through Web based tutorials.
I am very interested in this topic since I charge a number of batteries
(some non- sealed some sealed) by means of a (150 W max)wind generator and
2 pcs 64Wpeak solar panel.

TIA for any advice

Frank GM0CSZ / KN6WH

"Frank Dinger" wrote in message
news:EAo%b.20992$ft.6377@newsfe1-win...
One thing to keep in mind is that battery voltage changes with
temperature, and any float or trickle charger that doesn't take this
into account can shorten a battery's life considerably. So if you want
to get the longest life from your battery, you should make sure the
charger is properly temperature compensated.
=======================================
Roy , If the lead acid battery charging current is limited to 0.1C
,(example
a 15Ah sealed battery is charged at max 13.8 V with a current not
exceeding
1.5A) is temperature compensation then still a necessity to optimise the
battery's (usable) life ?
And if it is, in which temperature range ? I have not found this info
through Web based tutorials.
I am very interested in this topic since I charge a number of batteries
(some non- sealed some sealed) by means of a (150 W max)wind generator
and
2 pcs 64Wpeak solar panel.

TIA for any advice

Frank GM0CSZ / KN6WH
==========================================
I should have added to the above that my 'renewable energy' charging voltage
will never exceed 13.8 V.
If the batteries are charged to this voltage level any energy generated by
wind generator and/or solar panels will be 'dumped ' via a number of car
headlight bulbs, by means of a simple opamp/ transistor circuit driving a
number of pass transistors.

Frank GM0CSZ / KN6WH

"Frank Dinger" wrote in message
news:EAo%b.20992$ft.6377@newsfe1-win...
One thing to keep in mind is that battery voltage changes with
temperature, and any float or trickle charger that doesn't take this
into account can shorten a battery's life considerably. So if you want
to get the longest life from your battery, you should make sure the
charger is properly temperature compensated.
=======================================
Roy , If the lead acid battery charging current is limited to 0.1C
,(example
a 15Ah sealed battery is charged at max 13.8 V with a current not
exceeding
1.5A) is temperature compensation then still a necessity to optimise the
battery's (usable) life ?
And if it is, in which temperature range ? I have not found this info
through Web based tutorials.
I am very interested in this topic since I charge a number of batteries
(some non- sealed some sealed) by means of a (150 W max)wind generator
and
2 pcs 64Wpeak solar panel.

TIA for any advice

Frank GM0CSZ / KN6WH
==========================================
I should have added to the above that my 'renewable energy' charging voltage
will never exceed 13.8 V.
If the batteries are charged to this voltage level any energy generated by
wind generator and/or solar panels will be 'dumped ' via a number of car
headlight bulbs, by means of a simple opamp/ transistor circuit driving a
number of pass transistors.

Frank GM0CSZ / KN6WH

Jumping-in, Steve says...

"Frank Dinger" wrote in message
news:EAo%b.20992$ft.6377@newsfe1-win...
One thing to keep in mind is that battery voltage changes with
temperature, and any float or trickle charger that doesn't take this
into account can shorten a battery's life considerably. So if you want
to get the longest life from your battery, you should make sure the
charger is properly temperature compensated.
=======================================
Roy , If the lead acid battery charging current is limited to 0.1C
,(example
a 15Ah sealed battery is charged at max 13.8 V with a current not
exceeding
1.5A) is temperature compensation then still a necessity to optimise the
battery's (usable) life ?

It is the 13.8 voltage limit which must change as the temp changes. The
current limit, I believe, is less of a problem. The lead acid should be
able to take quite high current when it is still charging (in need of
charge) - when it is, it is converting the current into chemical
stored-energy.
This is what the common 'Sears' chargers do. Hit 'em with volts to get
lotsa' current to charge them quickly and make the human responsible for
"stopping at full charge".

--
Steve N, K,9;d, c. i My email has no u's.

When it reaches full charge, then it is producing H & O while decomposing
the water -- and probably heat.

And if it is, in which temperature range ? I have not found this info
through Web based tutorials.
I am very interested in this topic since I charge a number of batteries
(some non- sealed some sealed) by means of a (150 W max)wind generator
and
2 pcs 64Wpeak solar panel.

TIA for any advice

Frank GM0CSZ / KN6WH

Jumping-in, Steve says...

"Frank Dinger" wrote in message
news:EAo%b.20992$ft.6377@newsfe1-win...
One thing to keep in mind is that battery voltage changes with
temperature, and any float or trickle charger that doesn't take this
into account can shorten a battery's life considerably. So if you want
to get the longest life from your battery, you should make sure the
charger is properly temperature compensated.
=======================================
Roy , If the lead acid battery charging current is limited to 0.1C
,(example
a 15Ah sealed battery is charged at max 13.8 V with a current not
exceeding
1.5A) is temperature compensation then still a necessity to optimise the
battery's (usable) life ?

It is the 13.8 voltage limit which must change as the temp changes. The
current limit, I believe, is less of a problem. The lead acid should be
able to take quite high current when it is still charging (in need of
charge) - when it is, it is converting the current into chemical
stored-energy.
This is what the common 'Sears' chargers do. Hit 'em with volts to get
lotsa' current to charge them quickly and make the human responsible for
"stopping at full charge".

--
Steve N, K,9;d, c. i My email has no u's.

When it reaches full charge, then it is producing H & O while decomposing
the water -- and probably heat.

And if it is, in which temperature range ? I have not found this info
through Web based tutorials.
I am very interested in this topic since I charge a number of batteries
(some non- sealed some sealed) by means of a (150 W max)wind generator
and
2 pcs 64Wpeak solar panel.

TIA for any advice

Frank GM0CSZ / KN6WH

Frank Dinger wrote:
One thing to keep in mind is that battery voltage changes with
temperature, and any float or trickle charger that doesn't take this
into account can shorten a battery's life considerably. So if you want
to get the longest life from your battery, you should make sure the
charger is properly temperature compensated.

=======================================
Roy , If the lead acid battery charging current is limited to 0.1C ,(example
a 15Ah sealed battery is charged at max 13.8 V with a current not exceeding
1.5A) is temperature compensation then still a necessity to optimise the
battery's (usable) life ?
And if it is, in which temperature range ? I have not found this info
through Web based tutorials.
I am very interested in this topic since I charge a number of batteries
(some non- sealed some sealed) by means of a (150 W max)wind generator and
2 pcs 64Wpeak solar panel.

TIA for any advice

Frank GM0CSZ / KN6WH

I'm sorry, but I don't have an answer to your question. Actually, I'm
not sure there is a simple answer. There are a number of quite different
types of lead-acid battery, with different plate compositions,
construction, and electrolyte form (e.g., liquid and "starved" -- as far
as I can tell, gelled electrolyte is no longer used or is at least very
rare, in spite of the fondness hams have for dubbing every sealed cell a
"gel cell"). Each has its own characteristics, advantages, and
shortcomings. I heartily recommend a careful reading of the
manufacturer's recommendations for the particular battery you'll be using.

In more general terms, I don't think any lead acid battery manufacturer
recommends constant current charging at any level. Charging to maintain
a cell at full charge (float charging) is, in my experience, invariably
recommended to be constant voltage, not constant current, with the
voltage being temprature compensated (lower voltage at higher
temperature). The amount of current is then whatever the battery
requires to maintain full charge.

I did a quick google search of

lead-acid battery float charging "temperature compensation"

and came up with quite a few hits including some basic tutorials, a
couple of which were http://www.powerstream.com/SLA.htm and
http://www.emrg.ca/ideas&info/gel_cell/battery_care.htm. There are many
more available. But again, batteries can differ quite a great deal, so
you should really get information specific to the particular battery, or
at the very least, to the general class of battery, that you'll be using.

Roy Lewallen, W7EL