My boat has an Interstate Lead-Acid RV/Marine Battery the dealer installed
this spring. When I picked up the boat with this battery I noticed the
voltage was low (probably around 11.5 v?). I've charged it since, but it
seems to lose charge quickly.

I disconnected all leads from the battery for 3 days and it held 95% without
drop. Once I re-connect the wires, it lost 7% charge in one day (95% @12.75v
to 88% @12.63v), this seems like a lot of drop for not having any
accessories turned on. I'm certainily interested in a battery shut-off
switch... but perhas I should warranty the battery first?

Can anyone validate if this is unusually high capacity drop for a 35-40 ma
load (as measured by my digital voltmeter)?

"feetwet" wrote in message
news
My boat has an Interstate Lead-Acid RV/Marine Battery the dealer installed
this spring. When I picked up the boat with this battery I noticed the
voltage was low (probably around 11.5 v?). I've charged it since, but it
seems to lose charge quickly.

I disconnected all leads from the battery for 3 days and it held 95%
without
drop. Once I re-connect the wires, it lost 7% charge in one day (95%
@12.75v
to 88% @12.63v), this seems like a lot of drop for not having any
accessories turned on. I'm certainily interested in a battery shut-off
switch... but perhas I should warranty the battery first?

Can anyone validate if this is unusually high capacity drop for a 35-40 ma
load (as measured by my digital voltmeter)?

Stepping right up to the group flame throwers here.......... Lead acid
battery capacity cannot be accurately measured by the open circuit voltage.
There could be a battery fault here, but the tests so far don't mean an
awful lot. Although the 35-40 ma current draw without anything turned on
seems a little high for perhaps only one or two pieces of equipment with
"push-button" electronic off/on switching, it is certainly enough to take
the freshly charged voltage down a fraction over a day's time. In most cases
the freshly charged open circuit voltage will fall a half-volt or so over
two or three hours as the battery cools.

Verdict? Hard to be sure, but doesn't sound too far from normal.

You really, really need to have (and use) a battery switch.

Let the flames begin.

Old Chief Lynn

feetwet wrote:
My boat has an Interstate Lead-Acid RV/Marine Battery the dealer installed
this spring. When I picked up the boat with this battery I noticed the
voltage was low (probably around 11.5 v?). I've charged it since, but it
seems to lose charge quickly.

I disconnected all leads from the battery for 3 days and it held 95% without
drop. Once I re-connect the wires, it lost 7% charge in one day (95% @12.75v
to 88% @12.63v), this seems like a lot of drop for not having any
accessories turned on. I'm certainily interested in a battery shut-off
switch... but perhas I should warranty the battery first?

Can anyone validate if this is unusually high capacity drop for a 35-40 ma
load (as measured by my digital voltmeter)?



A continuous 0.040 ampere load over a 24-hour period is equivalent to
one amp-hour. I would not expect a fully charged lead-acid battery to
see that much voltage drop.

If the voltage was constant for three days prior to the test, the
battery was probably well-charged. The battery voltage will drop more
under load when the battery is not fully charged, however, and the only
way to really be certain is to use a hydrometer (inexpensive). Make sure
you get one that has temperature compensation.

An increase in battery temperature could also produce the result you
have observed.

As could a poor connection to the battery terminals.

Does the battery voltage increase again when you remove the load?

Chuck

In article . net, "feetwet" wrote:
My boat has an Interstate Lead-Acid RV/Marine Battery the dealer installed
this spring. When I picked up the boat with this battery I noticed the
voltage was low (probably around 11.5 v?). I've charged it since, but it
seems to lose charge quickly.

I disconnected all leads from the battery for 3 days and it held 95% without
drop. Once I re-connect the wires, it lost 7% charge in one day (95% @12.75v
to 88% @12.63v), this seems like a lot of drop for not having any
accessories turned on. I'm certainily interested in a battery shut-off
switch... but perhas I should warranty the battery first?

Can anyone validate if this is unusually high capacity drop for a 35-40 ma
load (as measured by my digital voltmeter)?

A little overcharging would probably help after sitting below 12 volts.
Not surprising for a less than perfect battery.

greg

Does the battery voltage increase again when you remove the load?

Chuck

No the voltage stayed the same removing the load.

The battery was down today slightly more at 85% @ 12.60v.

On Fri, 05 May 2006 01:03:15 GMT, "feetwet" wrote:



Does the battery voltage increase again when you remove the load?

Chuck

No the voltage stayed the same removing the load.

The battery was down today slightly more at 85% @ 12.60v.


12.6 volts is about right for a fully charged battery that has rested
for a day or so.

Regards
Gary

"Gary Schafer" wrote in message
...
On Fri, 05 May 2006 01:03:15 GMT, "feetwet" wrote:



Does the battery voltage increase again when you remove the load?

Chuck

No the voltage stayed the same removing the load.

The battery was down today slightly more at 85% @ 12.60v.


12.6 volts is about right for a fully charged battery that has rested
for a day or so.

Regards
Gary

12.6 volts sounds about right to me, but voltage is not a very accurate
indicator of charge for lead acid batteries. Cell electrolyte specific
gravity is a pretty good charge indicator ONCE the ACTUAL full charge
specific gravity is known for that one particular cell. (hopefully all the
cells are within a few points of each other....... what is the rule of
thumb...... 20 points difference?)

Old Chief Lynn

feetwet wrote:
Does the battery voltage increase again when you remove the load?

Chuck


No the voltage stayed the same removing the load.

The battery was down today slightly more at 85% @ 12.60v.



We are dealing with a lot of uncontrolled variables and that tends to
make firm conclusions difficult.

Normally, after a battery has been charged, the open-circuit voltage
will drop over a 24-48 hour period as the "surface charge" dissipates.
After that, the no-load voltage should remain fairly stable.

Technicians testing batteries often apply a brief load (e.g., turning on
headlights) to a recently-charged battery to rapidly dissipate surface
charge before testing. Your light load could be doing that, but it seems
unusual that the surface charge did not dissipate by itself by the end
of three days.

So all of this tends to fall in a grey area, somewhat outside what I
normally observe. Other posters find your measurements to be normal for
their experience. Sorry we can't be less equivocal.

Good luck.

Chuck

On Fri, 05 May 2006 01:03:15 GMT, "feetwet" wrote:

No the voltage stayed the same removing the load.

The battery was down today slightly more at 85% @ 12.60v.

12.6 is normal after sitting for a few days. I'd expect it to hold in
that range for awhile in the absence of any significant load.

"feetwet" wrote in
news
Can anyone validate if this is unusually high capacity drop for a
35-40 ma load (as measured by my digital voltmeter)?



Dump it. Batteries are LOTS cheaper than TOWING!