'Taylor,
Good info, except for a couple of important items.
Checking battery voltage with a voltage meter may and will very likely
give you a false reading if the batteries are sulfated.
Checking the condition of a flooded lead acid battery with a
hydrometer is the most accurate way to check the condition of that
battery. It will show if the battery is sulfated, has a bad cell or if
it is fully charged. The hydrometer is actually measuring the specific
gravity of the sulfate in the electrolyte fluid, so the hydrometer is
the key meter to use to test the state/condition of the battery. Yes,
a load test is good and so are the newer fancy meters, but they still
will not be as accurate and simple as a hydrometer.
Here is a good write up on causes of sulfated batteries, by Rolls Battery Co.
Battery Sulfation
Modified on: Mon, 11 Dec, 2017 at 12:24 PM
Causes of battery sulfation:
Batteries sit too long between charges. As little as 24 hours in
hot weather and several days in cooler weather.
Battery is stored without some type of energy input.
Undercharging of a battery to only 90% of capacity will allow
sulfation of the battery using the 10% of battery chemistry not
reactivated by not completing the charging cycle.
Low electrolyte level - battery plates exposed to air will
immediately sulfate.
Incorrect charging levels and settings. Rolls recommends a
3-phase charge cycle (Bulk, Absorption & Float) and a charge rate
equal to 10% of the C20 (20 hr AH rating) of the battery bank. See
State of Charge & charging information.
A battery sitting for extended periods in a partial or discharged
state is more likely to retain a build up of sulfation, which hardens
and is more difficult to remove through equalizations.
Studies have shown that nearly half of the capacity in an L16-style
battery may be lost if the regulation voltage is too low and the time
between finish-charges is too long.
In normal use, battery plates are getting sulfated all the time. When
a battery is being discharged the lead active material on the plates
will react with the sulfate from the electrolyte forming a lead
sulfate on the plates. When there is no lead active material and or
sulfate from the electrolyte remaining the battery then is completely
discharged. After a battery reaches this state, it must be recharged.
During recharge, the lead sulfate is reconverted into lead active
material and the sulfate returned to the electrolyte.
When the sulfate is removed from the electrolyte the specific gravity
is reduced and the reverse takes place when the sulfate is returned to
the electrolyte. This is why the state of charge can be determined
with the use of a hydrometer or refractometer.
If a battery is left in a discharged condition the lead sulfate will
harden and have a high electrical resistance. This is what is normally
called a sulfated battery. The lead sulfate may become so hard that
normal recharging will not break it down. Most charging sources,
engine alternators and battery chargers, are voltage regulated. Their
charging current is controlled by the battery's state of charge.
During charging, battery voltage rises until it meets the charger's
regulated voltage, lowering the current output along the way.
When hard sulfate is present, the battery shows a false voltage,
higher than it's true voltage, fooling the voltage regulator into
thinking that the battery is fully charged. This causes the charger to
prematurely lower it's current output, leaving the battery discharged.
Charging at a higher than normal voltage and low current may be
necessary to break down the hardened sulfate.
Hardened sulfate also forms in a battery that is constantly being
cycled in the middle of its capacity range (somewhere between 80%
charged and 80% discharged), and is never recharged to 100%. Over
time, a portion of the plate's active materials turns into hard
sulfate. If the battery is continually cycled in this manner, it will
lose more and more of its capacity until it no longer has enough
capacity to perform the task for which it was intended. An equalizing
charge, applied routinely every three to four weeks, should prevent
the sulfate from hardening.
In both cases, the fact that the battery "won't take a charge" is a
result of improper charging procedures which allowed the sulfate to
harden. In most instances, it is possible to salvage a battery with
hardened sulfate. The battery should be charged from an outside source
at 2.6 to 2.7 - volts per cell and a low current rate (approximately 5
Amps for small batteries and 10-Amps for larger ones) until the
specific gravity of the electrolyte starts to rise. (This indicates
that the sulfate is breaking down.) Be careful not to let the internal
temperature of the battery rise above 125° F. If it does, turn the
charger off and let the battery cool. Then, continue charging until
each cell in the battery is brought up to full charge (nominal 1.265
specific gravity or higher).This time needed to complete this recharge
depends on how long the battery has been discharged and how hard the
sulfate has become.
The next time your batteries don't seem to be taking or holding a
charge, check the specific gravity with a hydrometer. If all cells are
low even after a long time on charge, chances are you've got some
hardened sulfate that has accumulated on the plates. By following the
instructions outlined above, the problem may be corrected. [end of
article]
Joe, if your batteries are sulfated, you might be able to bring them
back with a couple of equalize cycles. Be sure that your electrolyte
fluid is topped off.
John
'95 Safari Serengeti 38ft, Cummins C8.3-300, Allison
6spd
On 9/30/19, W Taylor Hudson fpengr@... [Safarifriends]
wrote:
> All good advice, wanted to add a few more points.
>
> Specific gravity testing of electrolyte: typically performed with a
> hydrometer calibrated to indicate level of charge.
>
> No load voltage: after disposition of any “of surface charge” also an
> accurate way of ascertaining level of charge presuming your voltmeter is
> accurate.12.6 to 12.73 volts represents a 100% charge level at ordinary
> temperatures. There are temperature correction charts (slight depression
> of voltage as temps get really cold).
>
> Determining your state of charge is important in verifying part of the
> battery’s condition, and if your charging systems have been doing their
> job properly.
>
> That said, level of charge is not an overall indicator of battery
> condition. A battery with completely sulfated plates and virtually no
> capacity left would not be indicated being either of the above two checks.
> Either check does indicate a battery is ready to undergo the classic load
> test where a heavy load is applied for a short time and voltage is measured
> during the load application. A typical test would apply one half of the
> battery’s rated cold cranking amps for 15 seconds. At the end of the
> actual discharge, voltage should not be less than 9.5 volts.
>
> Interestingly a battery may pass a load test today and be unable to perform
> tomorrow (such as in cell shorts). I personally call this SBD (sudden
> battery death).
>
> When taking in a pair of 11 month old Interstate starting batteries that
> flunked my own load test, the battery distributor used a new tester which
> uses impedance, conductivity, or both to ascertain a battery’s health
> (batteries still started the coach fine). The device is about the size of a
> volt ohm meter with the same lightweight test leads (obviously not a load
> test). He explained the advantage of the new tester is that batteries that
> are not fully charged can be instantly evaluated, verses having to recharge
> them first. (The batteries were allowed to discharged completely before I
> purchased the coach. After recharging they started the unit fine, but I
> doubted their health after having a deep discharge. While I was not the
> original battery purchaser, nor did I have any proof of when the batteries
> were purchased, the age was determinable by a mfg code on the batteries.
> The distributor handed me a fresh pair of identical batteries at no
> charge)..
>
> I notice Harbor Freight appears to carrying such a battery tester for
> around $80.
> v/r,
>
> Taylor Hudson
> ‘98 Safari Serengeti (4960), CAT 3126
> acquired 2018
>
>
>
> On Mon, Sep 30, 2019 at 2:53 PM Gary Smith trekker01@...
> [Safarifriends] wrote:
>
>>
>>
>> Robert,
>> Don't you have tto disconnect the batteries to test with the HF device as
>> well? Each battery needs to be disconnected from other batteries and all
>> charging sources to get a valid test except possibly with a hydrometer,
>> testing the specific gravity of individual cells. And I suspect you want
>> each batttery fully charged AND at rest for these tests, with nor charge
>> source connected.
>>
>> Gary
>> '98 Sahara 3006 300CAT
>>
>> On Mon, Sep 30, 2019 at 2:34 PM Robert Lewis robert.lewis.tl@...
>> [Safarifriends] wrote:
>>
>>>
>>>
>>> I used a battery load tester from harbor freight $20. It draws down the
>>> battery thru a heavy resistor load. The meter tells the battery
>>> condition.
>>> You have to do each battery one at a time.
>>>
>>> The refractomer could be better as you would not have to disconnect the
>>> batteries, but I haven't used this method.
>>>
>>> Robert and Bev Lewis
>>> 2000 Safari Continental, since 2017
>>> 3126B Cat, 330hp
>>> MD3060 Allison
>>>
>>>
https://safaritoonces.org
>>>
>>>
>>>
>>> On September 29, 2019 6:34:00 PM "Sarah George jumpnjoe59@...
>>> [Safarifriends]" wrote:
>>>
>>>>
>>>>
>>>> So for the update. I unplugged the fridge and that didn't seem to make
>>>> a
>>>> difference. Which doesn't surprise me as the fridge has always been
>>>> plugged
>>>> into that receptacle (behind the fridge and have to access panel outside
>>>> of
>>>> coach to aceess). I have boondocked before with no battery issues
>>>> (always
>>>> for a weekend).
>>>>
>>>> Unplugged from shore power and turned on the fridge. It does show it is
>>>> running on L.P. and the batteries were measuring 12.16. Went out for
>>>> about
>>>> 2..5 hours and the batteries were measuring 11.6.
>>>>
>>>> I am now thinking weak battery/batteries or a circuit on the fridge. I
>>>> don't know of any other things that could have changed.
>>>>
>>>> Since I don't know how to trouble shoot the fridge I figured I would
>>>> get
>>>> the batteries checked first.
>>>>
>>>> Is taking batteries to an auto parts store to have checked a good idea
>>>> of should I take it them to a "battery" store. I have been told the
>>>> auto
>>>> parts stores don't necessarily do the most accurate checks.
>>>>
>>>> Joe/1997 Sahara/3550/3126/300hp/6 spd/2 years in
>>>>
>>>
>>>
>>
>> --
>> *Gary Smith*
>>
>>
>>
>
'