Do not charge (battery) under airtight conditions

[chex]

My fishfinder batteries, the big 7A ones Humminbird sells, have been lasting, at most, 2 hours lately, sometimes less. I've been wondering why, and have gone back and forth with Humminbird to no avail. I have 2 of these batteries, one of which is relatively new, and both provide no more than 2 hours of usage, so I thought perhaps the FF unit was defective in some way. Humminbird disagreed and said my batteries were probably defective, and I told them "no way, brand new battery, good charger, blah blah blah". So I ordered a new battery to stick it to 'em and say "look Humminbird, this battery is brand new and still it only lasts 2 hours, you see I told you so...".

So I got my new battery today, charged it up and hooked it up. The fishfinder stayed on for 5 hours before I eventually turned it off. Clearly, the FF is fine, and it IS my batteries that are faulty. Doh!

So now I'm wondering why.

On the side of the battery, there's a sticker that says, among other things, Do not charge under airtight conditions.

My 2 other batteries are sealed in drybags, which is close to an "airtight condition", and I do charge them in the bags. Could this be what is causing my problem??

[Shady]

Interesting, did you try charging the battery by itself (not in the drybag) and then seeing how long it lasted?

I'll have to remember to take the lid off of my battery box while charging from now on...

[chex]

Interesting, did you try charging the battery by itself (not in the drybag) and then seeing how long it lasted?

Not yet. I will. But I'm afraid I may have damaged the batteries already.

[dsiekman]

I always thought they said that due to an explosion risk, but perhaps not?

[jet]

batteries plus told me not to let them fully discharge, and keep them charged when not in use.

[zimm]

I always thought they said that due to an explosion risk, but perhaps not?

even sealed batteries vent gasses during the charge cycle so yes that's one valid reason not to seal them
heat is the second factor they build heat during the charging cycle .
if they are sealed units and they were mine - I'd shake them up a bit to suspend any materials that could be shorting cells out- this most likely won't work if they are gel type but I've seen it squeeze a few more cycles out of a wet cell.

Note: I did not suggest you do this

[dsiekman]

Not sure what the offgas is, but maybe that is causing your problem?

Also, have you checked the water levels if appropriate?

One more thought, I'm guessing these are similar to the batteries found in kids ride-on toys and my FIOS box. If so, one of the Verizon techs shared a little secret with me. CAREFULLY "whack" the battery a few times. If I remember right, it had something to do with knocking the oxidation off of the plates. I'm going to add the caveat that I'm not suggesting you do this, this is just what I was told to do with my FIOS battery and it worked. I was getting the dreaded faulty battery light and annoying beep. I took the battery out, smacked it a few times, plugged it back in, and it lasted me another six months! After a few cycles of this process I finally broke down and bought a new one.

If you need a new battery, check Battery Warehouse or a similar vendor. I've found they are significantly cheaper than other sources. Example: Volvo wanted somewhere around $275 for a new battery plus install - funny shape and size (goofy Sweeds). Battery Warehouse offered to install the same one for $120 out the door.

[dsiekman]

Note: I did not suggest you do this

Hehehe. Looks like we posted similar thoughts at the same time...and we're both equally paranoid! My paranoia comes from being an architect - too much liability not to be. What about you?

[chex]

I appreciate the tips.

Shake... and smack... got it. Sounds safe enough. If that doesn't work, i'll stick it in the oven for a bit to warm it up.

If I don't post anything tomorrow, come looking for me.

I don't think there's any water to check...

[Twistedfish]

The problem is the hydrogen being given off, both while charging and while in use. If you do a google search for lead acid batteries and airtight you will find several pages. Here is a good explanation from Battcon.com

I. AN OVERVIEW OF HYDROGEN GAS EVOLUTION

All lead acid batteries, particularly flooded types, will produce hydrogen and oxygen gas under both normal and abnormal
operating conditions. This hydrogen evolution, or outgassing, is primarily the result of lead acid batteries under charge,
where typically the charge current is greater than that required to maintain a 100% state of charge due to the normal chemical
inefficiencies of the electrolyte and the internal resistance of the cells. This excess charge electrolyzes the water in the
electrolyte mix of sulfuric acid and water, causing free hydrogen and oxygen to be vented from the battery.
In fact, flooded lead acid batteries will outgas at varying rates under almost all conditions, even in storage where minor
amounts of gas will be produced due to the normal evaporation of water and the tendency to self-discharge. In normal
operation (float voltage), flooded lead acid batteries are kept in a state of maximum voltage potential in order to maintain
maximum power reserve. This constant state of charge current causes the flooded battery to outgas hydrogen and oxygen
continuously; room temperatures higher than the recommended ambient (typically 20°C-25°C) will accelerate this
outgassing.

[zimm]

Hehehe. Looks like we posted similar thoughts at the same time...and we're both equally paranoid! My paranoia comes from being an architect - too much liability not to be. What about you?

Wifey works in the legal proffession

[HJS]

Last but not least, concentrated hydrogen and oxygen gases do burn, and maybe will explode, when contained in an air-tight container and subjected to a spark... like the spark you might get when you disconnect the charging clips.

[DOGFISH]

Sometimes even new batteries are defective. It may not be anything that you did. One thing that I have learned over the years is to not set your batteries on concrete. That will kill them fast. If it is not a deep cycle type battery, were they left discharged for a long period of time. The good thing is you are back in business.

[chex]

I think there are many things I did wrong with them, including draining them completely and not charging them right away. Sometimes they sat in my car for several days before I charged them.

Thanks for all the tips. I will take very very good care of this new battery.

[chex]

i think it's oversize and heavy but hopefully doesn't leave me flat.

How many Ah is yours?

I just ordered a 12Ah... 10Lbs compared to 6Lbs for the 7Ah. I should get 10 hours of continuous use out of it.