Ventilation of Battery Compartment

[Not Sure]

Correct battery venting:
Batteries H2 Venting - Free Hydrogen Vent

[CharlieJ]

Simply because you post something doesn't make it true.

Right back at you.

Also note that many high quality chargers used on boats include an automated equalization function

This feature absolutely must be disabled when charging AGMs.

and many such chargers are high amp fast chargers, meaning that the agm's connected to them are likely gassing regularly when connected to such chargers.

Sorry, again. High charging current does not cause lead acid batteries to gas, high charging voltage does. This is why temperature compensation is so important with all lead acid batteries and especially AGMs. AGMs can absorb constant voltage charging as high as their rated capacity and above. TPPL AGMs can absorb 2C to 3C.

Charlie

[CharlieJ]

Here is what the Code of Federal Regulations (49CFR173.159 (d) (i) and (ii)) requires of batteries that are air shippable; e.g., AGMs:

(2) For batteries manufactured after September 30, 1995, the battery
and the outer packaging must be plainly and durably marked
``NONSPILLABLE'' or ``NONSPILLABLE BATTERY''; and
(3) The battery must be capable of withstanding the following two
tests, without leakage of battery fluid from the battery:
(i) Vibration test. The battery must be rigidly clamped to the
platform of a vibration machine, and a simple harmonic motion having an
amplitude of 0.8 mm (0.03 inches), with a 1.6 mm (0.063 inches) maximum
total excursion must be applied. The frequency must be varied at the
rate of 1 Hz/min between the limits of 10 Hz to 55 Hz. The entire range
of frequencies and return must be traversed in 95<plus-minus<ls-thn-eq>5
minutes for each mounting position (direction of vibrator) of the
battery. The battery must be tested in three mutually perpendicular
positions (to include testing with fill openings and vents, if any, in
an inverted position) for equal time periods.
(ii) Pressure differential test. Following the vibration test, the
battery must be stored for six hours at 24 [deg]C<plus-minus<ls-thn-eq>4
[deg]C (75 [deg]F<plus-minus<ls-thn-eq>7 [deg]F) while subjected to a
pressure differential of at least 88 kPa (13 psig). The battery must be
tested in three mutually perpendicular positions (to include testing
with fill openings and vents, if any, in an inverted position) for at
least six hours in each position.

Charlie

[Not Sure]

Originally Posted by CharlieJ

Right back at you.


This feature absolutely must be disabled when charging AGMs.


Sorry, again. High charging current does not cause lead acid batteries to gas, high charging voltage does. This is why temperature compensation is so important with all lead acid batteries and especially AGMs. AGMs can absorb constant voltage charging as high as their rated capacity and above. TPPL AGMs can absorb 2C to 3C.

Charlie

Yes, but the difference being that I corroborate my post with a link to a battery company incontrovertibly stating that both agm's and gel batteries 'vent' (i.e. agm's 'explode less'.....'less' being the operable word here, not 'never'), while you attempt to back up your position that they don't by posting Federal regulations for airplanes, which certainly doesn't prove that they don't vent (or explode), but rather the required specifications that make them allowable for air travel. I imagine that gel cells also are air transportable, yet they vent even more than agm's, so the federal regulations are essentially meaningless to this discussion.

As to the charging current, you may wish to refresh your memory on 3 stage charging, paying particular attention to the second stage of charging where the current is reduced and voltage is increased.

[GordMay]

Originally Posted by CharlieJ

Here is what the Code of Federal Regulations (49CFR173.159 (d) (i) and (ii)) requires of batteries that are air shippable; e.g., AGMs:
Charlie

As noted by Not Sure, the CFR refers to liquid electrlyte "spillage"; not to out-gass or venting.

[davisr]

Hey Gord. At the bottom of the current thread I noticed a thread you appear to have initiated back in March 2006, titled "Battery Ventilation when Fast Charging." In reading through this thread I noticed that someone made reference to a battery compartment ventilation fan. I copied and pasted your words on this fan and include them here:

Thanks to Andina Marie, for the heads up ion the Zephyr Vent Fan!

The manufacturer’s website has a lot more information at Zephyr Industries Battery Box Ventilator:
http://zephyrvent.com/

I’ll be returning to this subject (soon ?), with a more detailed statement and recommendation.


I checked out the Zephyr Vent Fan site. Was this the sort of fan that you were talking about Charlie for the venting of the cockpit locker?

Thanks for all the help fellas,
Roscoe

[CharlieJ]

Your link sent me to a battery distributor's description of how to properly vent a battery box in a motor coach. I saw nothing on the site that remotely supports your erroneous position that AGMs vent.

As to the charging current, you may wish to refresh your memory on 3 stage charging, paying particular attention to the second stage of charging where the current is reduced and voltage is increased.

I honestly do not know where you are coming from. The classic three stage charging profile of bulk, absorption and float (to make sure we are on the same page, terminology wise) includes the constant current bulk stage, followed by constant voltage acceptance stage where the charging current slowly tapers off as the battery internal resistance increases, followed by floating at constant reduced voltage. That is how they are designed...that is how they operate.

Regarding venting, AGMs are valve regulated lead acid batteries (VRLA). The valve regulated part of their description comes from the relief valves on each cell that are designed to lift when the internal case pressure exceeds a setpoint. This is typically 2 to 5 psi. These internal pressures will not be reached unless the VRLA is exposed to charging voltage that is out of specification.

Charlie

[Not Sure]

Originally Posted by CharlieJ

Your link sent me to a battery distributor's description of how to properly vent a battery box in a motor coach. I saw nothing on the site that remotely supports your erroneous position that AGMs vent.


I honestly do not know where you are coming from. The classic three stage charging profile of bulk, absorption and float (to make sure we are on the same page, terminology wise) includes the constant current bulk stage, followed by constant voltage acceptance stage where the charging current slowly tapers off as the battery internal resistance increases, followed by floating at constant reduced voltage. That is how they are designed...that is how they operate.

Regarding venting, AGMs are valve regulated lead acid batteries (VRLA). The valve regulated part of their description comes from the relief valves on each cell that are designed to lift when the internal case pressure exceeds a setpoint. This is typically 2 to 5 psi. These internal pressures will not be reached unless the VRLA is exposed to charging voltage that is out of specification.

Charlie

So, you're unaware that during the 2nd stage (absorption) of 3 stage charging when the current is decreased and the voltage increased, it can actually overcharge a battery, particularly when under load....is that what you're claiming here?
Battery Chargers - Which One's For You - DonRowe.com

The bottom line is that all three types (fla, gel, agm) of batteries vent, whether you care to admit it or not. I'm guessing that you don't want to admit it because it puts you in the same boat as the guy with fla batteries in the lazarette that started this thread, i.e. you've got agm batteries that are venting into an enclosed space....probably your cabin.

It's also interesting how some folks apparently can't extrapolate how properly venting one enclosed space containing batteries relates to properly venting another enclosed space with batteries....like a boat.

[Stillraining]

To vent or not to vent...my wife goes into that mode every 28 days..

[CharlieJ]

Not Sure
Here is the section from your last posted link regarding three stage chargers:

A three-stage charger is the most complete charger. It charges the battery at a constant current until the battery voltage reaches a slightly elevated level. The battery is maintained at this voltage while the charging current diminishes to a low value, and then the battery is switched to the float voltage where it can be maintained indefinitely. However, the charger cannot differentiate between a current going to a load on the battery, or being absorbed by the battery, so it can overcharge a battery supplying current to a load. A two-stage charger is preferred for “loaded” batteries and a three-stage for idle or “unloaded” batteries during recharging. Samlex chargers which offer 3 stage charging can be switched to 2 stage if required by simply Adjusting a dip switch.

I see nothing about the adsorption voltage increasing during the second stage.

I do not understand your logic or opinions. And I am done.

[Not Sure]

Originally Posted by CharlieJ

Not Sure
Here is the section from your last posted link regarding three stage chargers:


I see nothing about the adsorption voltage increasing during the second stage.

I do not understand your logic or opinions. And I am done.

If you were to read more on the subject instead of being 'done', you'd see that many modern 3 stage chargers indeed up the voltage as they decrease the current in the absorption stage, (and that they are not _my_ logic or opinions, but rather the logic and opinions of those who design the chargers)...again, whether one cares to believe it or not.

[davisr]

Anybody had good luck ventilating a battery compartment on a boat with a zephyr, which appears to be made for the solar heating industry?


The manufacturer’s website has a lot more information at Zephyr Industries Battery Box Ventilator:
http://zephyrvent.com/

[Blue Stocking]

Just Curious!!--how many of you REALLY think your boat meets the relevent ventilation specs to which these valuable posts refer.

[GordMay]

Originally Posted by davisr

Hey Gord. At the bottom of the current thread I noticed a thread you appear to have initiated back in March 2006, titled "Battery Ventilation when Fast Charging." In reading through this thread I noticed that someone made reference to a battery compartment ventilation fan. I copied and pasted your words on this fan and include them here:
Thanks to Andina Marie, for the heads up on the Zephyr Vent Fan! ...
Roscoe

Here’s the thread to which davisr (Rosco) was referring.
➥ http://www.cruisersforum.com/forums/...ging-3344.html

I haven’t personally used the Zephyr Industries Battery Box Ventilator for marine battery ventilation; but linked to it, based upon the recommendation by Yandina*, whose judgement I generally respect.

*Ann-Marie Foster (“Yandina”) Yandina Marine Electronics

Yandina on Auto’ Battery Compartment Ventilation:

Automatic Controller ➥ Catalog Frame

Instructions ➥ http://www.yandina.com/acrobats/VentData12-24.pdf

[James S]

Originally Posted by Blue Stocking

Just Curious!!--how many of you REALLY think your boat meets the relevent ventilation specs to which these valuable posts refer.

I have AGMs in a vented battery box under my settee with a pancake fan switched by a voltage sensing module, that works great.
The fan exhausts to other parts of the settee which is open to large areas behind cabinets.
This is all meant to help keep the batteries from warming during charging.
It is my belief that these batteries will only vent gas if there is an error in charging i.e. over charging.
I hope that by having a good three stage regulator and thermal sensor this will not happen.
Before this set-up the boat had normal flooded batteries spread thru-out the area below the settee with no additional ventilation……..for 30 years.