Im referencing the Trojan guide for charging flooded batteries. They are a mix of old 8v Trojans and newer 8v Generic Brand. I have the charger set for 2.45v per cell. (i didnt temp compensate, weather app says its 65F right now) Trojan says to do a maximum of 4 hours absorption. At that time im still not dropping to the 1-3% finish charge range.I can tell the charger to drop to a constant current charge. Which i just did its at 2a for a 170ah battery. My question is how long do i leave it on the constant current finish? Ive read the Trojan guide over and over and all im seeing is " The finish phase ends when the battery is fully charged." How long is that? My charger does have a setting on what % to stop the charge at. I will have to check what its set to. I messed with it a couple months ago. Lets say i set it to 3%. That means when the charger hits the 3% finish charge the length of time would be zero. But that could be well passed the 4 hour absorption charge. Does a smart charger for flooded batteries have a time setting that automatically switches to a finish current? I would like like to use my charger to mimic what the smart chargers do. I dont have to wait for the 4 hour maximum absorption time to drop the voltage.I also dont have to follow Trojan 100%. When i ask advice before there were other brands people linked. I bookmarked their instructions but have not looked recently.Oh...i do have a tool to measure specific gravity. I dont think i want to dip it in these old batteries. I try to keep the tool all nice. Its only been used on my brand new 6v. I suppose the answer to my question is going to be that i cant use time. You have to use SG. Geez great. What about an educated guess on timing? New batteries versus older batteries. I swear some of these have to be 10-15 years old now.

I'd love to know what this is about. What kind of RV are we talking about?I guess I never heard of 8 volt batteries being used in an RV.All I can say is don't mix old batteries with new batteries.

Gee, I need to get from point A, to point B, but my tires are new, and I don't want to get them dirty.:)Use the hydrometer/ refractometer, and rinse it after each use, and before putting it away rinse it a bit better and dry it.When Amps stop tapering at absorption voltage, and start rising, call em done, is another method.Or are you afraid of wearing out the spring on your DC Clampmeter's clamp?I've had the absorption stage take 4 hours and I've had it take 14 hours, and I certainly wont be venturing a guess on your batteries.

wopachop wrote:Does a smart charger for flooded batteries have a time setting that automatically switches to a finish current? I would like like to use my charger to mimic what the smart chargers do. I dont have to wait for the 4 hour maximum absorption time to drop the voltageFirst did you mean to type 8V or did you mean 6V?Due to the way you worded the rest of your post.. the answers are the same no matter which you meant.. But I've not seen an 8/16 volt RV. only 12 volt (Two six in series make one 12). I also make many typos.Now.. to answer the question above yes and no depending on the charger.Some (IE Parallex 7300T switch modes based on an internal clockSome (most smart chargers I suspect) Measure current and voltage.Some.. are not as complex as their instructions. For example my Progressive Dynamics wizard Controlled speaks of 3-stage charging but as I recall the output voltage in "Bulk" mode is the same as in "Absorption" (The current drops is all) And from what I can tell that is the best.. From my voltmeter readings (I have a volt meter on a wall where I frequently look at it.. (Across from what is sometimes called "The Throne" you know the room where you use that roll stock everybody is panic buying now days. I'm a frequent flyer there for ONE reason, occasionally for TWO) anyway I see it dropping to "battery only" voltage from time to time so I think the wizard is basically pausing the converter in order to check battery voltage and changing modes based on that.But the bottom line is there are many ways to do it and different multi stage converters may use different systems.Oh the parallex 7300T that' T for Two and Two for Tea (As the old song goes) is a TWO stage.. bulk for a period of time THEN float. no absorption.

This is way over my head. My solar charges my four 6v using 14.8 volts and when I see the Panel voltage gauge jumps to 20v on the gauge and my battery voltage is over 13.5v..........it's done.

No can do ACCURATELY.Chemistry by derivites?Slightly less inaccurate guesswork?A census count after sundown by the number of rooms lit?

Understanding length of time for absorption & finish charge

MEXICOWANDERER
Explorer
May 24, 2020
Chemical reaction. Thermal acceleration of chemistry complicates things greatly. Cool it down to ambient temp.
wopachop
Explorer
May 21, 2020
Ah....5%. Hope it sticks this time. Im fairly certain they are 170ah and most of the batteries were taking 11-12amps to maintain the 2.70v per cell.

I screwed up and fell asleep early. Woke up and one of the newer batteries had been equalizing for 8 hours. It was taking close to 17amps to maintain the 2.70v. I was expecting to see the opposite. When i first started the charge i dont remember exactly but it was between 8-12amps to make the battery voltage 2.70v per cell. I set the charger to 17amps and it tapers down to whatever it takes to maintain the 2.7v per cell.

8 hours later it needed 17amps. Whats going on with that? If the batteries got hot, should resistance go down?

Felt bad because its not my golf cart. Hope i didnt damage that newer black battery by equalizing for 8 hours.
MEXICOWANDERER
Explorer
May 21, 2020
Press one time insert three copies.
MEXICOWANDERER
Explorer
May 21, 2020
For top charging and equalization use the FIVE PERCENT OF TOTAL AMP HOURS FORMULA. You have the two best analysis staring you in the face....

HYDROMETER SPECIFIC GRAVITY

HOW VIGOROUSLY or not are the cells bubbling?

TRENDS AND TENDENCIES
You can not manage flooded lead acid batteries without an accurate baseline of FIRST determining how voltage and amperage REACT to specific gravity readings. Think of it as going a million miles into space and then try and determine WHICH WAY IS UP...

Each entity of construction. Percentage of antimony, whether hybrid plate construction is used (calcium negative plates) or a myriad of other fundamentals are used or not determines the characteristics of your battery.

What the battery shows via instrumentation are the clues. Clues are dirivitives of specific gravity as measured with a hydrometer.

Managing a flooded lead acid battery solely by a rudimentary manual issued by the manufacturer is a fool's errand. Got it?

Far too many discrepancies between reading and reality. Electro chemistry is only understood precisely by someone willing to anchor baseline numbers and only the can they manage for awhile management via instrument numbers only.

Trends And Tendencies.

Manufacturers publish estimated number of cycles yet less than one half of one percent of users approach within forty percent of that number of lifetime cycles.

Look at the hydrometer reading FIRST and instrument readings SECOND.

Having an adjustable charger like a Magawatt makes this easy. A preset smart charger's prime directive is to argue and ignore reality.
wopachop
Explorer
May 19, 2020
Thanks red just seeing your reply. 5-10%
wopachop
Explorer
May 19, 2020
At 42 minutes the 5a charge left the voltage stable at only 9.77v and im looking for 10.8v.

Bumped it up to 10a charge and its now at 10.78v and still taking just about the full 10a and its 1 hour in.

Looks like the 5a charge is way too low. I think LY said he cranks the amperage up and equalizes real quick. Was with a neighbors 6v batteries i believe the example he gave.
red31
Explorer
May 19, 2020
step by step corrective eq
http://support.rollsbattery.com/support/solutions/articles/430-corrective-equalization-instructionshttp://support.rollsbattery.com/support/solutions/articles/430-corrective-equalization-instructions

step 3 - 3. Initiate the Equalization charge mode at a steady low DC current (5-10% of C/20 battery capacity). If grid power is not available, use a DC power source (generator) or PV array with sufficient current when possible.
wopachop
Explorer
May 19, 2020
Can you guys please lay me out again regarding equalization charge. These are 8v flooded batteries. Im able to trick my charger and say its a 10v battery and then adjust the individual cell voltage down to 2.16v. It only goes up to 2.60v and according to trojan i want to equalize at 2.7v

My question is about amperage. Im pretty sure trojan is saying i can charge at 20% of C20 to get up to the 2.7v per cell. But then i remember mex saying to use 5amp constant. Or maybe it was 10a. I know this came up several times over the last few years.

For really old batteries that we have been nursing for years, should i bring it up slowly with a 5a charge? Or that a waste of time?
BFL13
Explorer II
Apr 19, 2020
Yes, thanks. That answers my question very well.
full_mosey
Explorer
Apr 19, 2020
BFL13 wrote:
Not yet. Need time to review the linked threads.

EDIT--only understood some of that tech stuff. (Missed those threads as I don't follow the Technology forum.)

I see where after Mex jumped in it gets to my question, but I did not understand where it automatically drops to Float from Absorb based on amps. It seems to be based on estimated required Abs times depending on conditions?

Your estimated times have been worked out to get you down to the amps level quite well most times for your set up and conditions, but the actual amps level is not the trigger?

A new thread in Tech Issues can't hurt, but it is a lot of work for you to post all that complicated stuff I imagine.

I did create a new topic.

Automatic, smart battery charger? , part 2.

I hope this answers your questions.

HTH;
John

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