Wow. Nice rant! Very dense. Gonna have to space it out some to reply... (sorry Pete)
The math has nothing to do with whether it is telecomm or golf cart battery, there's no difference in the math.
Told you that you'd end up agreeing with me.
I just guessed wrongly that due to the 24 cell statement, which is common to telecomm, that this is where you got it from, but IT DOESN'T MATTER.
Right. Doesn't matter. So why did you bring it up? Your guess wouldn't have been wrong, if you hadn't been focused on something that - according to you - doesn't matter anyway.
Of course the application doesn't matter to the calculation and of course DWH's example calculation is terribly wrong.
There you go again. It *wasn't* MY calculation. It was an example from someone else's page. It was a calculation from GB Industrial Battery. According to their site:
"
GB Industrial Battery produces a full line of Industrial Forklift, Locomotive and Solar Batteries and chargers for the most demanding applications. With battery production centrally based in Illinois"
So if you don't like the math - tell THEM. It's THEIR MATH.
The 12 Volt car type batteries we use in this application are not made up of 24 cells, they are made of 6 cells, so your incorrect calculation is 4x wrong, not 2x, as well as being wrong in using the wrong AH determination. Two 6 Volts would still be 12 cells, the Op asked about both.
Again (and again, ad naseum) - it wasn't my calculation. It was an example, and I DID mention that the example was more than what we were talking about. Which you just keep conveniently ignoring.
The 6 Hour discharge rate is wrong
Um...yea...I already knew that. Interesting that you didn't mention it until I pointed it out. Sure you didn't just overlook it the first time around?
DWH's slimy planted traps were noticed by me – my way of stating that was when I replied that it wouldn't explode at 100%,
My slimy traps were noticed by you? I don't believe it. Would you care to point out some of the others? The ones that I haven't come clean and told everyone about already?
You no doubt must have noticed them.
though DWH stated that he “wasn't ready to accept” that hydrogen was combustible between 4-74% of volume.
That's not what I said. Read it again. I said:
"
density of 4% - which assuming your declaration that hydrogen won't burn at a lower density (which I'm not prepared to accept as a given)"
(And I was absolutely correct BTW. Hydrogen WILL burn at a density less than 4%. It depends on several variables.)
Wrong again, but I guess he accepts that now?
Accepts what? That you didn't read what I wrote, misquoted me and got it wrong?
But can you believe anything he says? Maybe that was just another slimy planted trap too-?
Yup. I got your attention focused.
And no, it wasn't a trap. All you had to do was pay attention and actually read what I wrote rather than just ignorantly (and arrogantly) dismissing it.
I noted the 6 hour discharge cycle used for the AH rating being wrong but chose to point out only the glaring 24 cell error in his calculation as “one of many”.
A) Sure you did.
B) Again...again...again...it wasn't MY calculation you (expletive deleted). It was AN EXAMPLE CALCULATION.
The youtube video is scary, sure it can happen
So...not sensationalism?
but to think that battery age, charge state, charge voltage, how close it is to the +ve and –ve plates being shorted due to age which cause plates to grow in to each other doesn't matter or is “irrelevant” is nonsense.
It is irrelevant. The only thing that is relevant is "hydrgen present? yes/no".
There is a reason why batteries blow
Actually, there are a lot of reasons why they *can* blow. But we're talking about hydrogen being vented by an open cell flooded battery under normal charging conditions.
All the rest is important, just not important in this context.
investigate and find out why - it just doesn't happen out of the blue for no reason, or else they wouldn't be able to sell them! Like I said - don't use old batteries, swap them out a regular schedule, depending on use or the number of discharge and charge cycles. Some manufacturers provide this data on the datasheet. Lots of things can happen, people don't always do what they are supposed to do or don't know. don't be one of those people. Should we never use jumper cables? Or should we know how to use them, understand the risks, and proceed? Or do we do nothing ourselves, be paranoid that there's electricity in the room, and just turn everything over to a shop to do?
Cant argue with any of that.
I didn't think this was that kind of audience on this forum.
100k+ registered members. More lurkers than that. The audience is of all types. Electricians and engineers are probably out-numbered by people who do think electricity is a magical and dangerous beast.
Apparently the thought is that H2 just stays in a pocket of a vented truck bed waiting for a spark, can collect in a pocket and that this "pocket volume" is the volume to base the combustibility volume % on, as if the H2 is not exposed to the complete volume of the truck bed with the cap on, or that H2 won't diffuse very quickly throughout the whole truck bed.
Yup, that's the thought.
How absurd. Yes it rises and very very quickly disperses.
What? Downward? It has risen and collected in a pocket. Where did it disperse TO? Nowhere - unless something blows it away, it's still there.
Like I said, prevent this by always having a vent – whether that vent is an opening or a fan or whatever.
Here's an idea - vent the battery box to the outside.
OK, so for the 6 volt batteries I wrote parallel instead of series, this was an obvious mistake for a 12V app, but again DWH makes the absurd statement that there is no voltage drop across connectors or connecting cables just because they are connected in series.
Oh...you don't even want to get me started on voltage drop.
My point was to oversize the connecting cables to minimize any charging voltage difference between two 6 volt batteries.
If they are in series, there is no charging voltage difference between the two batteries.
Man, that must mean I'm a expert poser and a terrible uneducated hack! OK - so I provided facts with formulas, used the words “science” and “math”, and other technical words, provided gassing rates and voltage specs – Damn I guess I was trying to baffle people! Or maybe I thought that there might be people who would be interested in details?
There certainly are.
Sorry, can't stop being an engineer, I thought there might be others on the forum who were interested in such things too.
There certainly are.
But how does it help the OP to muddy up his thread with a bunch of crap that has nothing to do with whether he should vent his battery box? Did he really need to be lectured about specific gravity?
(And, yes, I do realize the irony in what I just said - that I'm also muddying up his thread. But at this point, what the hell. I did try to keep it clean and simple at first.)
Guess I was wrong and didn't think that the people who are not interested would take offense to such thing - really? UFB. I also was wrong when I kept writing “cab” when I actually meant “truck bed”, which was the original posters question. Big difference. So rake me over the coals for all these things, I get how it works now.
I never said anything about cab. Never corrected you on that. Wasn't important.
Other than that I stand by what I said. Don't use a sealed battery box – this can be a cause of a battery explosion if the gas evolved when charging gets trapped inside a small volume box that can reach combustible levels quickly rather than the much larger volume of a truck bed with cap - even with a vent tube, you're one clogged tube away from gas not being able to escape a very low volume sealed box.
Right. No argument there. However, someone did post a recommendation to use a small tube. Which I would have said something about if I hadn't gotten sidetracked. A proper vent on a battery box is usually *at least* 1" diameter - and that's for a single battery.
This is what caused the huge explosion I said I was called in to analyze. A sealed battery box and a charger mistakenly left on equalize, a high voltage charge.
No argument from me. I've never advocated a sealed battery box.
Like I said - Use a vented box in a vented truck bed cap, isn't that the situation the original posted asked about? Don't overcharge, use the right charging voltage for the battery, don't charge a hot battery with the wrong voltage, don't sleep in an enclosed area with a battery on charge.
Doing well so far...
Understand that Hydrogen very quickly disperses and is generated at very small rates
Until here...
"Very quickly disperses" may or may not be true - because "it depends".
And it looks like our definitions of "very small" are not in agreement.
when on charge only, that overcharge is what causes higher gas evolution rates, and even a small vent will insure that combustible levels are not reached.
"Even a small vent"...
Here...I see that SBS Battery has an "online battery venting calcutor":
http://www.sbsbattery.com/products-...ions/battery-room-ventilation-calculator.html
Just plug in the numbers and let it run through the formula (beware the "gotcha" - it uses the 6 hour rate).
Even plugging in the most conservative numbers I can think of, it still requires a 1.5 cfm fan and a total air exchange every 163 minutes to achieve what they say is "the industry standard" of 1%.
I see they also say:
"
The concentration of hydrogen in the air should be kept below 1% to reduce risk of explosion."
But hell, they've only been in the business 100 years - what do they know about it?
But there's obviously no room for any one else but the glorious all knowing trap setting DWH on this subject, my mistake.
Aww, there's that snotty twit I've come to know and love. So cute!
What a bunch of stupid BS to come from trying to help out! Sorry if the information I provided offends your long held beliefs.
Nope, you haven't yet offended my long held beliefs. You'll have to try harder (and be more accurate).
I was just trying to allay fears the original poster had which I thought was about keeping a battery in his truck bed and whether he could safely sleep back there safely.
Oh...so that's why you dumped a bunch of techno-babble on the new guy's head? I'm sure this part here totally allayed his fears:
"
Lower charging voltage for temperatures over 77F,/25C higher charging voltage for temperatures below 77F/25C. It depends on the specific Gravity of the battery electrolyte but generally the charging voltage is determined at 2.25 volts +/- 5mV per degree F per "cell" above or below 77F or 3mV per degree C above or below 25C per "cell"."
Tell me again how I'M the one who is acting like he's "king of all battery knowledge"...
We should all never go in to Walmart where they have batteries on the shelves - too unsafe. Geez.
Batteries on the shelf aren't a problem - they aren't being charged. (Well, maybe they actually are all hooked up to a constant charge at Walmart. I wouldn't know, I don't shop at Walmart.)
EDIT: And I think you should note, that this reply to your rant, PROVES that I actually do take the time to read - and think about - what you write. If only you had done me the same courtesy, this whole clusterf**k could have been avoided.
