Does Battery Tender Release Gas During Charging?

[SR77]

Hello, I have read that a battery releases a flammable gas(Hydrogen I think) when it is being charged, does a Battery Tender release enough gas that one should be concerned about indoors like in a garage or basement? The battery would be in the car connected to the Battery tender all Winter in NJ.

The reason I am asking is because my garage where I store my classic car for the winter is attached to my house which is actually my sons bedroom and was going to buy a Battery Tender to keep up with the battery over the winter, but I am wondering if I should be concerned with the amount of flammable gas that could be released from it being that I have an attached garage and my sons room is so close to the garage.

In the past I would take the battery out for the winter and would have to charge it back up in the spring which is not great for the battery and thats why I was thinking of using the Battery Tender this year instead until I read about the gas release during charging and realized it would be connected out there all winter. Not sure if the Battery Tender goes to charge mode more often in the winter also with the cold temps.


thanks for the help

 

[George7941]

Batteries self-discharge less when cold, so the Tender will go into charge mode less often in the winter.

It would be perfectly safe to leave the Tender on inside the house. Any hydrogen released would be in very minute amounts. Probably there is more methane released from decomposing organic material stuck to the drain pipes upstream of the traps in your plumbing system.

 

[PDMc]

Assuming that you are talking about the type that goes into pulse mode after the initial trickle charge I would say that any gas discharge would be negligible in contrast to other sources of pollutants. What about the gasoline fumes from the gas tank, etc?

I'm not going to claim any expertise beyond experience here but I have never seen a battery generate any noticable gas discharge unless it was connected to a charger of significant amperage.

Some would say that you can't be too safe but I think we're getting into the hair-splitting zone. Of course then you would have to take into account all of the other stuff like fumes from carpeting & wall paint, etc.

Just my opinion. If it is any consolation I have 3 tenders running in my attached garage right now. Of course, sometimes I get drowsy...

 

[BigCahuna]

I use two battery tenders on my bikes that have glass mat batteries. so far it hasen't eaten the covers,and theres no smell in the garage. My Goldwing on the other hand has a lead acid battery and I don't use one on that for the reason it might boil out the acid or give off fumes. It may not, but I'm not willing to find out and have acid fumes attacking stuff in the garage.,

 

[heavyhitter]

I have had up to 6 ATV's and motorcyles running year round on Battery Tender Jr.'s fo rthe last 5 years. No problems at all.

 

[eljefino]

The big hydrogen danger is the spark from jumper cables etc. If the house is up to code (big if) you should have a couple layers of fireproof sheetrock between garage and house making it safe-ish.

That said my bike storage plan is just a 2 A charge a few hours a couple times mid winter... lots of stories of tenders (and knockoff trickle chargers) going nuts and overcharging.

 

[kgb007stb]

The battery tender just as any other trickle charger should have some kind of a bulk charge to bring the battery to a full charge which just about any good trickle charger can do. Once a battery reaches about 14.40V the current should start to taper off until the charge current is at 1/10th the bulk charge current at which charging should cut off and trickle charge takes over. Different manufacturers claim different trickle charge currents/voltages but the gist of the trickle charge is to be high enough to keep a battery topped off yet low enough to prevent any gassing. The voltage is usually around 13.30 – 13.80, some manufacturers build temperature compensation, but the trickle voltage should not trigger any gas release.

As a review when a battery reaches full state of charge with a dummy charger it will start to gas more and heat up internally as it tries to get rid of excess energy by breaking water into H and O gasses and dissipating excess energy through heat. This is why systems that suffer from poor regulation will “boil a battery away.” Boiling away a battery exposes the plates which causes them to oxidize. Boiling will also degrade the plates themselves through mechanical wear and tear which permanently damages the plates.

I myself am paranoid about ventilation during charging, but should you have enough large of a garage with lots doors being opened that should be enough to replenish the air and not allow the buildup of gasses. Should you not turn on any lights or accessories while battery is being trickle charged, normal charging will most likely never kick in as the trickle charge mode should produce enough current at the lower voltage to compensate for self discharge.

 

[SHOZ]

Get a sealed type battery. They won't vent unless pressure inside is around 10 psi or so. But if you had one of those batteries they don't need battery tenders anyway.

The Odyssey batteries I use require a 10 minute, 5 amp boost after winter to be back at full charge.

Any battery that is clean on the outside and in good shape internally should be able to go 3 months without a charge, better ones will go 6 months.

 

[brianl703]

As long as you disconnect the battery:

25mA parasitic draw * 24 hours = .6 amp-hours per DAY.

.6 AH * 30 days = 18 amp-hours per month.

18 amp-hours * 3 months = 54 amp-hours, or a dead battery.

 

[warrior pilot]

You want the batteryminder brand. There is a difference. It also depends what battery you are charging. Aviation, general automotive or deep cycle, even the brand of battery. Check out their site. I have a aviation type and a general purpose type.
To answer your question. No it wont matter if you use matteryminder. Others may not give same results.

 

[JohnBrowning]

Less you can push energy in and not get a reaction which in this case is gas that needs to vent.

 

[SR77]

Thanks for all the replies

Sounds like not much gas is released due to the current being lower in float mode so this is looking like the better option, but like some others here I might not trust it completely and would be worried with it not functioning right and over charging since this would be left out in my cold garage over the winter. I'm gonna have to think about this some more!

 

[swalve]

My understanding of battery chemistry is that they shouldn't ever give off hydrogen if they are properly charged.

(From memory, so I might be slightly wrong, and the chemistry is way simplified do I can understand it.)

The reaction at its most basic is like electrolysis of water to hydrogen and oxygen. You add energy (electricity) to the system and you get hydrogen and oxygen. The H and the O are now gasses full of energy and want to combine.

But we don't want an explosion, so we use the lead and the sulfuric acid to make the H and the O exist in a form that allows us to get the energy out as electricity rather than a boom.

When you put sulfuric acid into water, you get a solution of water, H ions and so4 ions. One plate is pure lead, one plate is lead oxide. As it gives off electrons, the sulfur moves to the lead oxide plate and replaces the oxygen. Which combines with two of the hydrogen ions making water, and some of the oxygen goes onto the pure lead plate making lead oxide. When it is fully discharged, we end up with pretty much a lead oxide plate and a lead sulfate plate, swimming in water.

Now we charge it back up. We push electrons into the system, which reverses the process. The electrons make the h2o want to separate out, and if its all going well, the oxygen recombines with the sulfur and the H goes back into solution as an ion.

However, because chemical processes take some time to occur, if we feed it more electrons than it can convert, the H and the O don't convert at the same pace. So what happens is that an H jumps free and becomes a gas. Leaving its "partner" sulfur and oxygen molecules stuck on the plates. The H escapes into the atmosphere, and the plates have become sulfated. You can't get that H back, and over time of improper charging, you lose more and more H and gain more and more sulfation.

So (as I understand it), the slower you charge a battery, the more likely it is that the H molecules remain in solution rather than jumping free.

So it stands to reason that whatever steps you can take to make sure the battery never gets too discharged means that the alternator never wants to charge the battery very hard. Meaning the battery lasts longer.

(That's why jumping a battery is potentially dangerous- it's completely discharged, and the electrical system of the other car can feed power into it so quickly that it can give off a lot of H. So much that it could go boom.)

Given that, as long as the trickle charger is designed correctly, it should never give off H.

However, if the trickle charger is not designed correctly or malfunctions, it could slowly overcharge the battery. Once the battery is fully charged, adding more electrons causes the water in the electrolyte to undergo electrolysis and cause H and O to both turn into gasses. Given the right (wrong) circumstances, you could end up with an engine compartment full of an explosive combination of H and O. Probably 99% of the time, there will be no underhood sparking and once you drive off it's gone. But that one time could be really, really surprising.

So, the point is, a trickle charger or battery tender is a good thing if it works right. But if it works wrong, it may be worse than doing nothing at all.

(If you could design a charging system that never over charged, and design lead plates that can perfectly exchange the oxygen and the sulfur without changing the structure of the plates, you'd have a battery that would functionally last forever. With nanotechnology, we're probably getting closer and closer. But currently, the sulfur and oxygen exchange process changes the mechanical structure of the plates and they eventually get brittle and fall apart.)

 

[George7941]

Great writeup, swalve. I have never had the chemical reactions in a lead-acid battery explained quite this way.

 

[SR77]

thanks for all the info

After doing some reading on batteries i might spend the extra money for a sprial cell AGM battery next. These supposedly have a very low self-discharge so they can sit in storage for months at a time. Plus the are not flooded with acid, and are completly sealed from fumes. Basically they sound like the are much safer to keep around the garage/house then a flooded battery. Then if I need to get a trickle charger down the road for the times where it sat for too long I can just hook it up and worry less about it exploding. I might even look into a deep cycle one too for longer storage ability.

 

[TooManyWheels]

I have been around two battery explosions. One was a battery which had been on a charger under an unvented cowling on a race car, and was triggered by me connecting terminals in the wrong order and shorting positive to ground.

The other was a heavy equipment battery which had welding done within a few inches of it.

Unless your garage or vehicle has zero airflow and also contains major spark sources, the chances of an explosion are slim.

 

[440Magnum]

All lead-acid chemistry batteries release some hydrogen when they're charged. But with a trickle or 'tender' type charger, the amount released is very small, plus hydrogen is SO much lighter than air that it quickly heads up and out of any confined space. H2 is also a pretty small molecule so it goes through very small openings. In other words, any H2 released by the battery from a battery tender won't likely accumulate in enough volume to worry about.