Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and measuring
voltage with time. The only problem is that this may take a few hours.

I don't think so. Look he www.batteryfaq.org.

====

Charles T. Low
- remove "UN"
www.boatdocking.com
www.ctlow.ca/Trojan26 - my boat

====

"Rick & Linda Bernard" wrote in message
...
Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and
measuring
voltage with time. The only problem is that this may take a few hours.

I don't think so. Look he www.batteryfaq.org.

====

Charles T. Low
- remove "UN"
www.boatdocking.com
www.ctlow.ca/Trojan26 - my boat

====

"Rick & Linda Bernard" wrote in message
...
Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and
measuring
voltage with time. The only problem is that this may take a few hours.

On Sat, 24 Jan 2004 05:00:54 -0600, "Rick & Linda Bernard"
wrote:

Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and measuring
voltage with time. The only problem is that this may take a few hours.


I use a hydrometer, myself. The specific gravity of the cells tells
you what condition they are in. 1.270 is a fully charged lead-acid
battery at 72F. Be sure to get a good hydrometer with a built-in
thermometer and calibration chart because the specific gravity of the
electrolyte is very dependent on temperature.

If you find a cell with gravity lower than the rest, be assured it has
suffered sulphation where the lead sulphate has crystalized and will
soon have a "dead cell", if it's not already.

If the cell has high specific gravity and the battery's voltage
doesn't drop under normal loads, it's fine. Just keep her topped up
with ONLY distilled water.

Of course, AGM batteries you have no way of knowing what the hell is
going on inside the sponges.....

Here's some references for you:
http://www.nwes.com/using_batteries.htm
http://www.thesolar.biz/Measuring_sp...ty_article.htm
http://www.usbr.gov/power/data/fist/...6/3_6_cont.htm
http://www.buchanan1.net/lead_acid.shtml
(people up Nawth need to pay particular attention to the table on
the bottom of this webpage relating to the electrolyte freezing
temperatures as related to cell specific gravity (charge).)
http://www.rpc.com.au/products/efn/e...ries_care.html
http://www.solartech.com/aboutbat.htm

and I think this cool instrument would be a great replacement for the
Link, which I don't think gives you an accurate assessment because the
Link runs on an assumed A-H battery rating and that rating is ONLY
good at a SPECIFIC LOAD CURRENT at a SPECIFIC TEMPERATURE none of you
are running on these batteries. The actual specific gravity is the
ONLY way of actually measuring a battery's condition. This neat
$US110 instrument stuck in one cell will constantly measure that
gravity. Isn't this actually CHEAPER than the Link?!....(c; I know
it's more accurate.
http://www.electrosense.com.au/
Wonder how long it will last in the acid environment?


Larry W4CSC

Is it just me or did the US and UK just capture 1/3
of the world's sweetest oil supply? What idiot wants to
GIVE IT BACK?!!

On Sat, 24 Jan 2004 05:00:54 -0600, "Rick & Linda Bernard"
wrote:

Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and measuring
voltage with time. The only problem is that this may take a few hours.


I use a hydrometer, myself. The specific gravity of the cells tells
you what condition they are in. 1.270 is a fully charged lead-acid
battery at 72F. Be sure to get a good hydrometer with a built-in
thermometer and calibration chart because the specific gravity of the
electrolyte is very dependent on temperature.

If you find a cell with gravity lower than the rest, be assured it has
suffered sulphation where the lead sulphate has crystalized and will
soon have a "dead cell", if it's not already.

If the cell has high specific gravity and the battery's voltage
doesn't drop under normal loads, it's fine. Just keep her topped up
with ONLY distilled water.

Of course, AGM batteries you have no way of knowing what the hell is
going on inside the sponges.....

Here's some references for you:
http://www.nwes.com/using_batteries.htm
http://www.thesolar.biz/Measuring_sp...ty_article.htm
http://www.usbr.gov/power/data/fist/...6/3_6_cont.htm
http://www.buchanan1.net/lead_acid.shtml
(people up Nawth need to pay particular attention to the table on
the bottom of this webpage relating to the electrolyte freezing
temperatures as related to cell specific gravity (charge).)
http://www.rpc.com.au/products/efn/e...ries_care.html
http://www.solartech.com/aboutbat.htm

and I think this cool instrument would be a great replacement for the
Link, which I don't think gives you an accurate assessment because the
Link runs on an assumed A-H battery rating and that rating is ONLY
good at a SPECIFIC LOAD CURRENT at a SPECIFIC TEMPERATURE none of you
are running on these batteries. The actual specific gravity is the
ONLY way of actually measuring a battery's condition. This neat
$US110 instrument stuck in one cell will constantly measure that
gravity. Isn't this actually CHEAPER than the Link?!....(c; I know
it's more accurate.
http://www.electrosense.com.au/
Wonder how long it will last in the acid environment?


Larry W4CSC

Is it just me or did the US and UK just capture 1/3
of the world's sweetest oil supply? What idiot wants to
GIVE IT BACK?!!

You need to borrow a load tester. It is just a heavy duty heat sink which
draws current from the battery. If the voltage drops during the test, the
battery is dying.
I have to borrow one to test my setup come
Spring

--
Dennis Gibbons
dkgibbons at optonline dot net
"Rick & Linda Bernard" wrote in message
...
Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and
measuring
voltage with time. The only problem is that this may take a few hours.

You need to borrow a load tester. It is just a heavy duty heat sink which
draws current from the battery. If the voltage drops during the test, the
battery is dying.
I have to borrow one to test my setup come
Spring

--
Dennis Gibbons
dkgibbons at optonline dot net
"Rick & Linda Bernard" wrote in message
...
Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and
measuring
voltage with time. The only problem is that this may take a few hours.

When you say testing, are you referring to determinining the
current state of the battery or the capacity of the battery. Determining
the current state of charge can be done by disconnecting the battery
from all loads, letting it sit for 24 hours and then testing the voltage.
For a liquid lead-acid battery, a full charge will be 12.8v, half
charge is 12.2v. For gels 12.6v and 12.0 are reasonable figures.
As Larry says below, checking the S.G. with a hydrometer is
standard practice if you have liquid batteries. Needless to say that
this can't be done with gels and AGM.

If you are trying to determine the capacity of the battery then a
slow discharge is needed. The manufacturer usually rates the
capacity based upon the 20-hour rate. So it you have a 200AH
battery then discharging it at 10 amps will discharge it in 20 hours.
(discharge is defined as 10.5v in this case). No real need to go that
far, but taking it down to 12.2v would be half capacity and should
take around 10hours. This will give a pretty good indication of the
health of the battery. I usually just turn on enough lights to get up
to the current I need for the test. Of course you have to deal with
people constantly telling you that you have left your lights on.

Good Luck!
s/v Callista

"Rick & Linda Bernard" wrote in message
...
Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and
measuring
voltage with time. The only problem is that this may take a few hours.

When you say testing, are you referring to determinining the
current state of the battery or the capacity of the battery. Determining
the current state of charge can be done by disconnecting the battery
from all loads, letting it sit for 24 hours and then testing the voltage.
For a liquid lead-acid battery, a full charge will be 12.8v, half
charge is 12.2v. For gels 12.6v and 12.0 are reasonable figures.
As Larry says below, checking the S.G. with a hydrometer is
standard practice if you have liquid batteries. Needless to say that
this can't be done with gels and AGM.

If you are trying to determine the capacity of the battery then a
slow discharge is needed. The manufacturer usually rates the
capacity based upon the 20-hour rate. So it you have a 200AH
battery then discharging it at 10 amps will discharge it in 20 hours.
(discharge is defined as 10.5v in this case). No real need to go that
far, but taking it down to 12.2v would be half capacity and should
take around 10hours. This will give a pretty good indication of the
health of the battery. I usually just turn on enough lights to get up
to the current I need for the test. Of course you have to deal with
people constantly telling you that you have left your lights on.

Good Luck!
s/v Callista

"Rick & Linda Bernard" wrote in message
...
Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and
measuring
voltage with time. The only problem is that this may take a few hours.

Load testers are good for starting batteries but don't really tell
much for a deep cycle battery.

Doug
s/v Callista

"Dennis Gibbons" wrote in message
et...
You need to borrow a load tester. It is just a heavy duty heat sink which
draws current from the battery. If the voltage drops during the test, the
battery is dying.
I have to borrow one to test my setup come
Spring

--
Dennis Gibbons
dkgibbons at optonline dot net
"Rick & Linda Bernard" wrote in message
...
Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and
measuring
voltage with time. The only problem is that this may take a few hours.