Does "Flash charging" mean we (some of us anyway) are wrong to hate it when the PowerMax or Iota converters drop their voltages so soon for the absorption stage?In another thread Mex says, "A flash formula is to achieve absorbsion limit (I prefer 14.8) as fast as possible then maintain it there until all battery cells start to bubble lightly, then back off to an intermediate voltage, perhaps 14.0 volts. The bubbling will subside at the lower voltage, but when it resumes, drop the charge rate to float."I think Mex is saying he likes to have no constant amps stage at all, but have such a high charging rate (charging amps wrt size of bank in AH, that the voltage spikes to the top immediately and amps taper while voltage remains constant at the high point for a time after that(This thread linked below is about something else, but I need to refer to the graphs in its OP and this is the easiest way to show them with my computer lack of skill.) So that would look like the later recharges in the second and third graphs here I think, where the bank has shrunk in AH, making the charging rate higher, and so the constant amps stage is lost.http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/24849190.cfmBut then he says to wait during the absorption stage till bubbles start and then drop the voltage. BUT that means when you reach "gassing voltage", which I thought was when you first reach that (14.x volts) which in Mex's case would be right away not later.Or are we getting into the tiny bubbles counting again? I don't think taking the caps off is practical or desirable for normal recharging, but ???I don't know if Mex's flash profile would get you high enough in SOC before the bubbles make you lower the voltage. I would want to keep the voltage at its high point until at 90% SOC anyway (doing 50-90s)You wouldn't do a generator recharge above 90% SOC, so that seems to suggest Mex lowers the voltage sooner. But that would reduce the amps acceptance rate, and slow down the recharge, but Mex says the flash method is the fastest.So, Mex, what is it that I am missing ? Thanks

CHEMICAL REACTIONYou will bring a discharged antimonial battery immediately to 14.8 volts AND IT WILL NOT BUBBLE. Not right away.But you can take the same battery under the same conditions and apply a voltage LIMIT of 14.2 with LIMITED AMPERAGE and three days can pass and the battery will be actually gassing freely.This is a battery generator charge issue. With power pole voltage time is not an issue. With solar it can become an Alice In Wonderland guesstimate which I will not touch with a twenty foot hotstick due to limitless permutation possibilities.No calculation will arrive at the same conclusion as my advice. It is an electrochemical phenomenon that has to be observed by trial and error innumerable times.Charging a battery formulae is every bit as intricate as Peukert's is for discharge. AMPLITUDE (voltage) and TIME. There are conclusions that can damage a battery. Other conclusions WILL NOT WORK. TIME SPENT AT VARIOUS VOLTAGE is the key. It cannot be done accurately with amp hour resolution but kWh is workable but too complicated except for nerds and it really is in the end, not necessary.Some cherry pick phrases, and statements out of one of my battery charge rants and come back days later with a statement that is soooo out of context it makes me want to cry.The instant absorbsion voltage limit recipe for charging is for GENERATOR CHARGINGBUT WAIT! THAT'S NOT ALL! THERE'S MOREThe recipe is specifically designed to reduce generator run time to a skeleton bare bones minutes.But all of the components of the recipe must be followed without fail. A setup designed to produce instant vmax is not something that can be changed to "Well yup I'll crank 'er up and I figger three hours otter do it, then I'll come back and check for bubbling (in reality the aroma of Yellowstone National Park). A person has to pay attention, and follow advice. A SMART PERSON will realize this formula is REPEATABLE, so they check the TIME that has passed between initiation of vmax, 14.8 bubbles, and the amount of time that passes after voltage is reduced to second stage v/intermediate, and bubbling. It is REPEATABLE and PREDICTABLE. I can take a weak sister cell dip and spin the dial on the Intermatic timer, and the percentage of charge will be so close to full when I return, it freaks people out. Two stage vabs. The EXACT same protocol I have designed with BORG with.Charging is something like deciding "Gee my car gets 12% better gas mileage at 55 than it does at 70 mph). But a three day trip turns into a four day drip and an extra hotel bill is involved. Save forty dollars on fuel and blow ninety bucks on the hotel. In this case it's fuel cost AND HASSLE versus battery life.A GUESSTIMATE has arrived at a conclusion that a battery will live 85% of the life as a battery given manufacturer recommended 20% of amp hour vabs charge. Compare this to fuel cost. I have and I am NOT going to spend a HUNDRED DOLLARS PLUS in extra fuel to afford fifteen dollars worth of life to a battery. This does NOT COUNT the money spent and time lost to go buy more fuel or time spent and money lost to learn an early generator rebuild is going to cost hundreds perhaps a thousand dollars or more.Charge Efficiency Ratio. Books to keep tabs of expenses. A run hour meter. And an intangible - how much does a person love to hear excessive generator use, in the case of lift and run away generators, the extra hours spent nursemaiding their safety?When electrolysis occurs, it is a dead giveaway that excessive energy is being consumed in a battery. Some of it is a necessary abstract by-product. But when it reaches a certain point it becomes a waste, and excessive heat enters the picture. So vabs MUST BE MONITORED to make sure excessive bubbling does not occur. A Lawrence Welk Bubble Machine Bubble Counter isn't necessary. Common sense is. The 2nd stage is just as critical. When bubbling is light, the battery is telling the world, "I've had enough". Just like it did at the 14.8 volt 1st stage. Time to revert to float.This is where a solar panel or two is par excellence. A 13.6 volt third stage for even as much as 6 hours would top the batteries off astonishingly full. So tah-dah, the generator charging should be done earlier in the day along with chores that demand 120vac appliances be used. This allows the solar to do it's chore which the fickle battery petulantly demands - that last 4% to 6% that electrochemistry resists with a jutting lower lip.

Didn't see my question (poorly asked) answered. Try again here---I can't get the battery voltage to spike to 14.8 as my Vmax unless I hit a 50% SOC battery with maybe a 45% charging rate or so. Lower charging rate will mean it accepts the charger's max amps steady (constant amps with current-limited charger) for a time and then it gets to 14.8 at a higher SOC later on. (The lower the charging rate, the higher the SOC before it gets to 14.8, and longer time before it gets there and vv)I have a bank of four 6s, call it 440AH, and I can muster 155 charging amps, so that is a 35% charging rate. I will not spike to 14.8 right off, I would need more charging amps going in.But let's pretend I have enough charging amps and generator to run that many amps on my size of bank so it does spike to 14.8 right away.I got from above reply that bubbles will not start yet, but I know amps will be tapering at the constant 14.8. No problem so far for fastest charging.The question is---how far up in SOC will the battery bank be by the time the bubbles are enough to reduce the voltage and so the amps?I am worried that it might only be 70% SOC (half of a 50-90 done) and I am shooting for 90%. I think Mex is saying that since it is already gassing, some of the amps is being wasted making heat, so it doesn't hurt your charging time to reduce the voltage and lower the gassing.BUT--then how can you monitor that you are still getting the 70-90 part done just as fast by using AH counting? You do have an AH counter (Trimetric) but you don't really know how much goes for heat either way ( leaving it at 14.8 or dropping to 14.2) so how do you know when you get to 90% and can stop the Gen?Mex says try it at home and get some before and after measurements till you get it right, and then just use the same "markers" (times, etc) when actually doing this away camping, because it will come out the same.Has anybody done this (including Mex if he has the data) with some examples of how far you got up from 50% SOC at the 14.8 before the bubbles got going so it was time to reduce the voltage? If it was at 90% anyway, then who cares? But if it was at 70% then it matters for how you can get from 70 to 90 as fast as just leaving it at 14.8 and never mind all the gassing.BTW this would be another great excuse for having the adjustable voltage charger, so you can lower the Vabs to whatever you want when you want! :)

My observations with a 150 AH Trojan T-1275 that was beat up when I got it free, and I got another 2 years out of it, all on Honda Eu2000i generator time and solar panels, with an Adjustable Voltage MegaWatt 30 amp power supply unit, and an RC watt meter.I'd pull 35-50 amps a day out of the battery... 60-70 SOC most mornings. RC watt meter told me voltage, and amps the battery was taking and cumulative amps charging.Usually an hour at 14.8 to an hour and 15 to an hour and 20 was enough to get my amp charge rate to drop to 9 or 10 amps, off from the 29 to 30 amps it would take at first charging for 3 or 4 minutes. Tiny bubbles after the first 15 or 20 minutes, very, very very tiny bubbles. At an hour to hour 15, when the amps charging rate was 9-10 amps, I shut the generator down. That was it, the end of bulk charging. 150w Solar panel was then employed, usually set at 14.0V. 8.8 Amps was possible from the panel, but more normal was 6 to 6.5 since the panel was portable and aimed almost always at the sun. 2 or 3 hours would drop the amperage down to about 4.5 Amp being taken. At this time, a peek inside would reveal slightly bigger champagne bubbles, a little bit more vigorous. Time to reset the charge controller to 13.6V for the rest of the day on solar.I always knew that no matter what, my trailer was always drawing 1 AH in parasitic draw, all day long, with nothing on or running.A week of this, and time to mix things up, charge on the generator first thing in the cold morning at 15.0V, for 2 hours on the generator, a "top" charge and 16.0V with the solar panel for 90 to 150 minutes, for desulphation or equalization charging.This almost always tuned up the battery, Specific gravity would be 1.275 to 1.280, with the weakest cell, doing 1.250 to 1.260. The T-1275 was an anomaly with this.This battery saw 500 -600 recharge cycles in a golf cart before I got it. I'd say in 2 years since I got it, at the end, I added 100-120 recharge cycles to it.With generators, I don't worry about tiny champagne bubbles when recharging at 14.8V. I begin to get concerned when they get soda pop sized like soda water in a clear glass, that's when I try to time it to drop the voltage. That or when the battery won't take something like a c/15 charge rate, or 10 amps on the RC watt meter. Time to go to the solar panel, drop the voltage then and slow the take rate down, letting the battery pass a 90% state of charge without bubbling and a c/15 charge rate for a few hours. My observation with an RC watt meter is that the take rate in amps will tell you a lot about when to drop the voltage, further dropping the amp take rate. About 9 to 10 amps at 14.8V on a 150 Amp Hour battery with my 30 amp Megawatt was that cut off point, regardless of time on the generator. When it got that low, it was time to cut the generator and go solar. This was with a high 6% antimony sweeper /golf cart battery, that was very beat up. They will bubble, a lot, and they will use water, but a lot less water if you only use voltage and amps as stated, the RC wattmeter, for me, worked almost as well as the acid dip and an SG reading. Taking some regular notes and responses tells one a lot. So does the stench of rotten eggs when a battery is dying, or surprise corrosion that starts growing on the battery terminals all of a sudden, from sulfuric acid off gassing. Of to the recycler it goes, then.Now I have a Telecom AGM "acid rich" 1.300 SG battery. And a 10 turn pot on the MegaWatt. Voltage sits at 14.4V... and I watch the amps drops that the MegaWatt puts out, while at home, on the grid. When the RC watt meter says .13 Amps for take rate, she's topped off and ready for storage. Usually takes 3 to 4 hours to do this after a 2 week long trip in the travel trailer.AGM batteries are a whole other world, compared to flooded lead acid batteries, which seem to have huge losses while recharging, due to resistance to charging in the battery.

I think the actual time it takes to get the gassing a happenin will be different for each battery, and charging amps, and temperature, and battery health. So any data collected and reported here, might not have much validity for another system at a different point in time and place.The beauty of an Ammeter on an adjustable voltage charging source is one can see the results, directly of raising or lowering voltage. But one needs a voltmeter on the battery terminals, not one just inline on the possibly undersized overlength cabling.I've been finding that a while after I first get my AGM to 14.46, and amps start tapering into the low 30amp range, if I reduce voltage to 14.0 the amps flowing at 14.0 are not much less, perhaps 2 to 3 less, than what was required to hold 14.46.Same general test on the screwy31 and the amps it accepted at 14.0 was perhaps half of what it took at 14.9v iirc.I think for generator charging, you'll still want to hold absorption voltage at the battery terminals for as long as you are willing to run the generator. But next time your amps are tapering at 14.8v, try lowering voltage to 14.0 and see the difference on your trimetric. If it is not a huge difference, then perhaps 14v would be less abusive and only marginally slower. I move my 10 turn pot way past 15volts as measured by the 8awg leaded wattmeter when I am seeking to get the battery to 14.7 as fast as possible as I have some 8 gauge and a few connectors in route to battery terminals from the Meanwell.If I set it to 14.7 unloaded, then plug into the batteries, amps start tapering earlier, So I crank it way past its unloaded voltage to keep that 40 amps flowing until the battery terminals read 14.7, or Whatever voltage I choose.I'll bump off the voltage as the amps taper and the voltage drop becomes less of a factor, IF the time I have to recharge is limited.Turning the voltage dial higher is easier than upgrading the charging circuit in my case. A little less convenient.Now, if I had an Amperage potentiometer that could go from 0 to 40 amps, I'd never stop laughing maniacally.Perhaps the Fanless Meanwell hep-600-15 which claims to adjust current from 18 to 36 amps and also has constant current limiting on overload:http://www.meanwell.com/search/HEP-600/HEP-600-spec.pdfMy 500 watt meanwell will output 600 watts so I imaging this 600 watt unit will also be able to exceed its rating

I have never quite understood the notion of "how many amps does it take to support the voltage"I set the charger voltage and how many amps I get depends on the battery at anything below charger max amps limit. I have no way to change how many amps that is except to change the voltage on the charger which also changes the voltage on the battery.I don't know how you can see voltage falling off when the charger is set to that constant voltage. I can see how the "marker" for when to stop the gen could change when you use the amps amount as they taper, like my 5 amps per 110AH = 90% SOC at 14.5v rule of thumb. 220AH would be at 10 amps. If the battery has lost AH, then the amps at 90% would be lower than usual. But that is still at 14.5 volts.

Mex's Flash? | Good Sam Community

MEXICOWANDERER
Explorer
Dec 10, 2015
Where I camp down here, there is far far less light than this. When I parked a bus in the sun at Xcalak I had a 24/7 generator and THREE roof airs going to keep interior temps in the 80's and humidity in the sixties. Maybe it's different up there, running a generator marathon style down here is a loser. Fuel, access to fuel, fuel cost make it ridiculous. Slow charging a battery bank is like barbecuing a steak one briquette at a time.

I had neighbor's kids make a palm frond and bamboo cocoon for the bus. For the shade. Solar works when it can work. Where it can work.
KJINTF
Explorer
Dec 10, 2015
No flashlight aka torch needed
Why would anyone ever stay in a place like that
Might as well go to a trailer park and pay home owners dues
MEXICOWANDERER
Explorer
Dec 10, 2015
Anyone got a flashlight? I need to find my solar panels!
pianotuna
Nomad III
Dec 10, 2015
If you have 150 watts of solar per 100 amp-hours of battery, a great controller, and decent solar conditions shore power is not much of an issue. It may have a long pay back at 12 cents per kwh.

Perhaps when LI becomes main stream and inexpensive we can all leave generators at home.
MEXICOWANDERER
Explorer
Dec 10, 2015
I had my attention pulled 16-different ways yesterday and failed to answer a perfectly valid question...

"What about generated heat?"

How many calories does it take to raise battery components by say a Delta T of 30 degrees? The difference between air temp and electrolyte temp...

Less emissions than what it takes to charge a battery by the V/max method. By the time the battery is even thinking of getting too warm the charge is over with. The intermediate level of 14.0 allows the electrolyte to cool down.

Batteries that DO raise temperature excessively HAVE SOMETHING WRONG WITH THEM. They are either bad or sulfated.

And hysteresis absolutely does enter the picture. V/max charging accentuates this variance. But a fast dip after the protocol finishes and rests will confirm the validity of the process. The process is an algorithm.

Algorithm - Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Algorithm
Wikipedia
Jump to Informal definition - In mathematics and computer science, an algorithm ( i/?æl??r?ð?m/ AL-g?-ri-dh?m) is a self-contained step-by-step set of operations to be performed. Algorithms exist that perform calculation, data processing, and automated reasoning.

If you're camped where fuel is NOT an issue, price is of no object, neighbors are generator noise tolerant, then charging at V/max may be completely idiotic reasoning.

Nothing will EVER replace the ease and compliance of Power Pedestal battery management. But then why not wander across the city and rent a penthouse suite with room service and a wet bar? To each their own...
BFL13
Explorer II
Dec 10, 2015
Reviewing the last 50-90 I did camping in October, I don't see where I can apply the Flash procedure anyway. Here is a quick look (without an ugly graph)

Bank of four 6s, temp 9C/48F, estimated Bank size at the time approx. 400AH. Charging amps going in 155a set at 15v (=14.8 at that temp) Bank down 192AH at start = 52% SOC

Time, amps, battV, AH replaced according to Trimetric ( including using its heat factor) Note- only one decimal place V makes it choppy.

0900, 155, 14.0, -
0915, 141, 14.2, -
0930, 117, 14.3/4, 77
0945, 99, 14.4,-
1000, 69, 14.4, 117
1033, 42, 14.5, -
1100, 27, 14.6, 159 (if 159 is 40% then 100% is 398AH) so in ballpark for estimated bank size.

Ok, so the thing is, battery voltage only got up to near 14.7 when charger voltage was 15, at the end of the two hours at about 90% SOC.

So when would I have seen the bubbles and lowered the charger voltage?

I would have to trust my home testing results as my "marker" for whether I got a 50-90 done or not instead of the Tri if I wanted to treat the batts better without so much gassing. (On the Tri it would look like I didn't get as many AH in during the 2 hours)

As it is I don't know how much bubbling I was getting in that recharge, so it might not be so bad anyway. Have to check for bubbles next time.
NinerBikes
Explorer
Dec 10, 2015
BFL13 wrote:
Sounds good, but I expect "SG lag" to ruin that plan. Worth a try at home for a test run though.

http://www.engineersedge.com/battery/specific_gravity_battery.htm

True, but even with the lag, you will get a timer setting, and SG reading (even with lag) and an idea of when to modify and drop your voltage.

The key is to know when the bubbling is getting too vigorous, the voltage at the battery terminals either climbing too fast, or how much time V at the battery terminal has been at 14.8V, that it's time to go to absorption voltage. Call it trends and tendencies. You don't have to get it perfect, close is good enough, before the temp of the battery electrolyte gets too hot. All these observation signs are correlated, there's multiple ways to skin a cat, or look at one observation or reading vs another, to know when to cut the generator or drop the voltage from 14.8V, and that bulk charging stage is over, next step, absorption charging voltage is now needed.

None of us mere mortals with batteries will ever get to the level of observations or perfection as MW does when it comes to balancing all the variables of costs of fuel, oil, motor time, rebuilds, cost of replacement batteries, replacement fuel, replacement generators.

We can do our best and strive to be close... take notes, learn, and try to do better. But that's about it... a man has to know his limits, try to break them to do better, without failing and doing destruction while trying. It's all about trade offs, even with my little Honda and single telecom battery. I charge hard, it's not the money issue or cost of repair to me... my priority while camping is quiet time... more than listening to any generator... so when mine runs, the sooner it gets shut off, and I get quiet time back, the better... my priority... YMMV on what is important to you.
BFL13
Explorer II
Dec 10, 2015
Sounds good, but I expect "SG lag" to ruin that plan. Worth a try at home for a test run though.

http://www.engineersedge.com/battery/specific_gravity_battery.htm
NinerBikes
Explorer
Dec 10, 2015
BFL13 wrote:
So, if you don't have enough charger/generator to get the batts to instant Vabs, can you apply this idea when there is a time while the battery rises to Vabs and then starts the absorption stage? I think I missed that info exactly.

So if I am doing my 50-90 and it gets to 75% when the battery reaches 14.8, I should lift the caps and start looking at bubbles. If it is only bubbling hardly any, I can keep going at 14.8 till it is bubbling "lightly" and then drop the voltage. So now I am at maybe 80% SOC, then do the 80-90 at the lower voltage? (but same amps into the battery so no time is lost?)

Or is it too late because it will already be bubbling "lightly" when it finally gets to 14.8?

Just experiment and take notes on when your battery starts bubbling, and how gentle to how vigorous your battery is bubbling, and add in a few specific gravity readings on the cells. By the time your SG is at 1.250, look at if it's bubbling. Keep reading SG until it's 1.260 and note the level of bubbling, Read the SG at 1.265 and look at how it bubbles, all at 14.8V. Somewhere in there, in that range, you'll know what point to shut off the 14.8V and charge at a lower voltage, say 13.8 to 14.0V, for absorption charging. Also note the time spent charging at 14.8 V when you do your SG readings. It should be clear from the above when the time spent charging at 14.8V is over.

You should very clearly notice a change in the level of, or how vigorous the cells are bubbling, at those states of Specific Gravity at 14.8V. Then compare it with how the battery bubbles at 14.8V with a Specific Gravity of 1.240.

If a SG of 1.210 is 50% charged and a SG of 1.275 to 1.280 is 100% charged, what would you estimate the SG to be at 80% SOC? 90% SOC. 80 to 90% is where the battery starts getting stubborn, showing resistance, and needing time at lower voltage instead of brute force voltage/amperage... the chemistry inside the battery is that it gets harder for sulfur on lead plates to find free hydrogen and oxygen in the electorlyte to bond to. Hence, bubbling is stirring up the electrolyte so that the free hydrogen and oxygen can find the sulfur on the lead plates, bond with it, and remove it. There's less sulfur to bond with, hence the charge rate and ability to take amps is reduced. Now it's a time issue, not voltage or amperage issue, to finish off charging the battery, it can't be rushed. The generator is inefficient at this point of the charge cycle.

That's the Dummy's version of how it works... MW could give you the full blown Calculus and derivative model of finding the area under the curve on that charge cycle... me, I just know that like most things in life, the closer you get to full, or 100% perfection, the harder it gets, the more expensive it gets, to get the least amount of percentage of gain. Just the way it is.

Batteries bubbling while recharging is a qualitative judgement... voltage, time, amps, and specific gravity readings are quantitative. Until you get a better feel for how all the quantitative readings mesh together, and some experience, it makes qualitative judgement difficult, just looking at bubbles.
BFL13
Explorer II
Dec 09, 2015
So, if you don't have enough charger/generator to get the batts to instant Vabs, can you apply this idea when there is a time while the battery rises to Vabs and then starts the absorption stage? I think I missed that info exactly.

So if I am doing my 50-90 and it gets to 75% when the battery reaches 14.8, I should lift the caps and start looking at bubbles. If it is only bubbling hardly any, I can keep going at 14.8 till it is bubbling "lightly" and then drop the voltage. So now I am at maybe 80% SOC, then do the 80-90 at the lower voltage? (but same amps into the battery so no time is lost?)

Or is it too late because it will already be bubbling "lightly" when it finally gets to 14.8?

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