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Old 30-11-2007, 23:19   #1
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Deep Cycle Battery Gassing


Taking a look at the great new batteries Wheels is installing and then reading the operational notes that for the much taller Tubular Plate battery. “Once the gassing voltage is reached charging is continued with plenty of current (and therefore high voltage). The resulting gas generation ‘stirs’ the electrolyte and ensures that it becomes well mixed again. More gas generation is needed than in a much lower flat plate battery”

So if my storage space for 6-800Ah batteries is under the dinning table then gassing might be a big issue?

Any idea how much gas we are talking about and any tricks to solve it (No nearby vents to outside)
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Old 30-11-2007, 23:48   #2
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Not sure if you're talking about flooded (I think those are the only ones that emit hydrogen; they're the only ones I know anything about anyway). Not a lot of people vent their battery compartents from what I've seen, but I installed one the other day just because hydrogen scares the crap out of me.

It's 16x lighter than air, so a vent near the top that lets it float away some how would be handy. I think the more you use them the more hydrogen they give off. Again, I only know about regular flooded stuff.
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Old 01-12-2007, 06:50   #3
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Not a lot of people vent their battery compartents from what I've seen, but I installed one the other day just because hydrogen scares the crap out of me.
There is a small amount sulfide in the gas as well as hydrogen. The hydrogen isn't anything that can accumulate but the sulfide isn't a good thing. The failure to vent can cause corrosion where the batteries are located. I had a small amount of it on my A/C exchanger as the batteries were in the same locker as the A/C unit. I doubt you'll get enough to make it dangerous but the corrosion problem is quite real.
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Old 01-12-2007, 09:20   #4
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I think my fear is from my days on a submarine where the batteries were much bigger, and the atmosphere closed. Explosive gas build up was a real issue. I guess I can stop freaking out on a tiny sail boat though.
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Old 01-12-2007, 09:37   #5
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And while we're at at:

I have read online that batteries do NOT give off anything other than O2 and H2 when charged at normal charging parameters (under 14.4 volts). This was from an MSDS sheet on Exide batteries.

Everything I've read says the batteries give off only these two harmless (although explosive) gasses.

If they give off hydrogen sulfide, this is a major health concern, as the MSDS on that is pretty clear - you can die from it like CO.

So what's the story?

Do deep cycle lead-acid batteries give off H2S, or just H2 and O2?
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Old 01-12-2007, 09:46   #6
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I thought hydrogen sulfide only comes from rotting organic matter. It stinks to high heaven regardless; smells like rotten eggs / farts. The stuff on the submarine we needed to vent was regular hydrogen. The stuff built up quite easily.
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Old 01-12-2007, 11:10   #7
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Originally Posted by rebel heart View Post
I thought hydrogen sulfide only comes from rotting organic matter. It stinks to high heaven regardless; smells like rotten eggs / farts. The stuff on the submarine we needed to vent was regular hydrogen. The stuff built up quite easily.
Everything I read suggests this as well. H2S is the "rotten eggs" smell. I've never smelled that coming from a battery before.
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Old 01-12-2007, 11:42   #8
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The H2 comes from the electrolysis of water. Anytime you apply an electrical current to water, it splits the Hydrogen and oxygen. That's how the oxygen generator on the submarine worked as well. I suppose it's possible that current applied to sulpheric acid might let off a little H2S, although I never heard of it being a signifigant amount either.
I thought it was interesting in the quote above about
Quote:
The resulting gas generation ‘stirs’ the electrolyte and ensures that it becomes well mixed again. More gas generation is needed than in a much lower flat plate battery”

On the submarine we always watered the battery after a normal charge and right before an equalizing charge (which we did monthly) so that the gassing that occurred during the equalizing charge would stir up the freshly watered cells. Something I think a lot of people miss when maintaining their own boat's battery. We also forced air down a tube to the bottom of the batteries to keep them mixed (they were 4' tall)
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Old 01-12-2007, 12:07   #9
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gassing vs excessively vigorous gassing

Stationary batteries develop what is called "stratification", i.e. different continuously increasing specific gravity from top to bottom. This stratification does not allow a uniform charge or discharge current to/from the plates.

Boats with minimal motion in the water do not usually suffer stratification and, therefore, vigorous gassing merely to remove stratification is not so important as it is in the case of stationary batteries.

Excessive vigorous gassing causes tiny droplets of the H2SO4 sulpheric acid to be carried on the bubbles of gas past the vent caps. Because vent caps have tiny holes designed not to pass much of a droplet size (or accumulation of droplets in the vicinity of the tiny hole) it is recommended to remove them and place them over the holes so that no internal pressure can develop in the battery caused by closed vent cap holes.

Regardless, if excessive vigorous gassing occurs long enough the droplets will be carried some distance outside of the battery, perhaps to your nose where you will smell what is like rotten eggs caused not by H2S so much as by the S04 combining with the mucous membrane. A little will not harmful for short periods of time because you can perceive parts per million that is easily dilluted in the membrane. This perception is a good warning to decrease charge current (often happens with attempts at equalization using currents greater than or sometimes equal to 7% of the Amp-hour rating or for too long).
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Old 01-12-2007, 17:02   #10
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The sulfide ion HS- will not be present, until the ph rises, up to at least 4, a very very dead battery.

H2S will not be produced, the odour is as rick suggests the sulphate ion entrained with water in the off gases.

I would vent the battery compartment.

To avoid H2 build up due to overcharging, and corrosion due to acid entrainment and possible spills.

Doesn't really matter what type of lead acid battery, cause you may need to replace a sealed battery, with a non sealed battery, at some inoppurtune time.
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Old 01-12-2007, 17:08   #11
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Stratification in batteries is in the boundry layer between the acid and the plates.

Bulk straification within the acid does not occur to any great extent, the diffusion process is far to fast.

Over charging to bubble your batteries can reduce this stratification, but is best left until the sulphation of the plates is becoming severe.

Bubbling with air is done and works well, but only with large batteries with big access ports not typically found on sailboats.
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Old 01-12-2007, 17:16   #12
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The additional need to gas was specific to the tall tube type of batteries and seemed to be a regular part of charging
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Old 10-12-2007, 14:28   #13
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Sorry about all the Font Codes guys. Have tried for about an hour to not show them when I post here

I am now using Vista and when I post all the Font Codes pop up. Does anyone know how to stop that??

(I had to manually delete most of them)

[FONT='Arial','sans-serif']
Deep Cycle Battery Choices (from China)
[/font]
[FONT='Arial','sans-serif'][FONT='Arial','sans-serif']

As I am in the Philippines, the availability of batteries from Asia is part of my research to upgrade the Deep Cycle capacity from 400AH (24V) to 6-800AH (24V

A few of the 24v Diesel Ducks from China are now putting in Deep Cycle IBT batteries 12 x 2v units: series BTS-600TG to 800TG [/font]

OPzV series batteries utilizes tubular grids and fumed silica electrolyte of latest technology.The batteries are adopt to high temperature & overcharge & proof against deep discharge, And will not dry out . There is no risk of leakage during the service life and transportation, extra suitable for severe environment. The design life up to 20 years(25oC

I am also considering putting in 6 of their 12v

IBT HC Series batteries are designed for deep discharge application, with special chemical formula for plates active paste material, slightly stronger electrolyte and low temperature design, which can withstand repeated deep cyclic application, such as Solar Energy System, Golf Trolley, Electric vehicle

Can someone with more product and technical experience than I confirm with me the pros and cons of either choice for house battery purposes (especially when it comes to fast charging rate) and your opinion on these batteries. I am presently getting quotes and will share that when it comes in

Thanks…..Nick

http://www.ibtbattery.com [/font][/font]
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Old 10-12-2007, 14:34   #14
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Ever blown up a hydrogen balloon? Exciting, but not a huge deal. It's not like you are going to blow out any windows or blow up the boat like you see in James Bond movies.

For you home gamers, you can make your own hydrogen by mixing NaOH which is Sodium Hydroxide (drain cleaner) and strips of aluminum in water in a five gallon container. I did it as a teenager and released drycleaner bags of it over the house. At night we made our own UFO's Don't try this at home kids.
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Old 18-05-2014, 08:45   #15
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Re: Deep Cycle Battery Gassing

I wanted to resurrect this thread for discussion, if you guys don't mind. I just came from a seminar yesterday where the presenter said he did not recommend installing flooded cells in living spaces on boats because charging batteries produced hydrogen sulfide.

I did not believe this, and told the guy so. Maybe not as tactfully as I could have. I thought I would check this morning to see if maybe I was wrong, and the internet is full of people spreading this story.

Personally, I don't see how this could happen, except possibly under very unusual conditions, but wanted to check for other opinions. Any thoughts?

Cheers!

Steve
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