Latest Equalize Charging w 20 Amp Solar Charge controller

[NinerBikes]

NOTICE: Disconnect battery from RV before trying this, you don't want to damage any on board electronics with charging with voltages this high!

I have this unit hooked up to 150W poly solar panel, 18.0V and 8.3 Amps rating Imp.

Just fiddled with this particular 20 Amp PWM Solar charge controller that I bought on Amazon, for around $32.50
20 amp solar charge controller


and found that it can be adjusted to 16.0V to do an equalize charge on my T-1275. Which means no more fiddling out with switching wires to do that every 10 to 12 day Equalize charge any more, Like I used to have to do on my Solar 30.

Today's equalize got up to 15.91V before it started falling again, measured at the battery terminals with my Digital Multimeter, after 1 hour and 6 minutes, on my Trojan T-1275.

I set the voltage down to 13.2 V after it reached that, a float voltage.

Might be worth looking in to this unit if you have a fussy to charge battery like a Screwy 31, or a T-1275, something car jar shaped for a battery instead of golf cart or unrestricted design considerations like tall batteries in industrial applications, like Mena 661.

I usually perform this special function before going on a camping trip, and when I get back with the TT to the storage yard, before putting away for a while.

[MEXICOWANDERER]

That's why The Borg was built or more accurately - is being built. AGM batteries do not appreciate 50-90% recharges.

Not knowing what is going on inside an AGM, was voiced by me on this forum several years ago. Deducing voltage and amperage (incidental and hours) trends and tendencies is critical. Most AGM battery owners do not subject their units to repeated long-term 50-90% cycling. Some lightweight users will jeer "My AGM does not require all that babying". Be aware of why that is an answer containing a falsehood within a truth.

[NinerBikes]

The take away is that always, once past 80% state of charge, the battery acceptance rate and time determine how close you get to a 100% state of charge, on a daily basis.

That should be the goal, daily, to restore as close as you can, as best you can, a 100% state of charge, with all the charging systems you have available to you. It will require adjustable voltage charge controllers, and it will take voltages a lot higher than the battery maker attorneys are willing to insure.

But my take, like landyacht318's experience has been to bump the voltage, but be mindful and respectful, and monitor what you are doing, until you know what you are doing, to top charge, and to equalize charge to recharge the slacker weak sister cell to whip 'er back into shape and pulling more of her own weight.

Specific gravity readings only, will tell you when you are at 100% state of charge. All cells uniform at a specific gravity of 1.275 or slightly higher. Battery voltage readings are completely unreliable, only a guideline to be met when top charging or equalize charging... a goal, but not an absolute, to insure 100% SOC. Dipping and Specific Gravity readings never lie. They are absolute fundamental laws of chemistry, physics and mass.

This is all in reference to flooded lead acid batteries.

[Naio]

Yes, I do have AGMs, and thank you, Landyacht!

[landyacht318]

Kind of funny rereading the first page on the screwy 31 thread, when ~2 months old and not recharged properly, it was holding lower voltages than it is right now with 300+ more cycles on it.

Shows how important proper recharging is, and what a good learning experience this screwy 31 has been, when having the tools to measure it, and adjustable charging sources able to find the sweet spot that made the battery the happiest.

[landyacht318]

Naio, you have AGM house batteries If I remember correctly. Theses should not be brought upto these rather extreme equalization voltages.

Lifeline AGM has a 'conditioning' procedure, very similar to a flooded Equalization cycle, to attempt to restore capacity on Cranky Lifelines, but no other AGM manufacturer I know of says this is acceptable.

Lifeline has a very good technical manual worthy of a Read:

http://www.lifelinebatteries.com/manual.pdf

It is harder to know when an AGM is truly fully charged. I've been using the amperage it requires to hold Absorption voltage on my NorthStar group 27 AGM battery, at 14.7v. When it requires less than 0.4 amps to hold 14.7v, I consider it fully charged. However, if it was cycled more than 10% and not recharged at a high initial rate of at least 25 amps, I notice it cannot crank my engine with the same impressive gusto. Mostly it is used as an engine starting battery. So While I do not cycle my AGM battery often, when I do, I make sure I can employ my 41 amp Meanwell power supply, or am driving with engine rpms over 1200 for long enough so that my well cabled '130 amp' alternator can feed it as much juice as it wants to take.

MaineSail has a good read about AGMs as they apply to the boating world and some main points he brings up is that it is more important to return AGMs to 100% charged than it is flooded batteries, and that they require higher charge rates when deeply cycled:

http://forums.sbo.sailboatowners.com/showthread.php?t=124973

[NinerBikes]

Naio wrote:
What is this that I am supposed to be doing? Are you charging them till the battery has 16v?! Or using a 16v input? And, without solar, how do you get such a high input?

Start here, and read all the pages 3 times. Then come back and see if you have any questions.

Linky

[Naio]

What is this that I am supposed to be doing? Are you charging them till the battery has 16v?! Or using a 16v input? And, without solar, how do you get such a high input?

[NinerBikes]

mexicowander would claim that ticking is the pacemaker your screwy 31 is on, shortly before the bell tolls.

[BFL13]

That ticking?

https://www.youtube.com/watch?v=mKKDsELi0o4

[landyacht318]

Before I got my Meanwell rsp-500-15 my only method for getting the battery to 16V was resetting ABSv and float voltage to 16V on my solar controller, and I need at least 6.2 amps to get the screwy 31 up there.

Well my Schumacher sc2500a would occasionally go nuts and bring the battery upto 16.4v blasting it with 10+ amps, but that does not count.

Now it is just a twist of the dial.

I love the RC watt meters, although my GTpower version is inaccurate at very low currents.

I removed the 14awg aluminum leads and soldered and shoehorned tinned 8awg into mine, since it will pass 41 amps for as long as my batteries want to accept that, at the voltage I choose to let them feed. I have another one I need to do the same to. 45Amp anderson PP's on 8awg, crimped and soldered, instead of just crimped.



Might have to check SG on the screwy 31 soon. I've been neglecting it lately, and hammering it to below 12v at night, and so far it is pulling a Timex in response to the abuse.

What's that ticking?

[BFL13]

It is all about how long do the batts remain undercharged. If you get to near full every day, then an overcharge once a month is fine.

If you sit there for a week letting the batteries slowly fall to 50% before recharging, that is harder on them for sulfation, so now you would need to equalize more often--even once a week after that one recharge they get a week.

"It depends."

[pianotuna]

Thanks for sharing that info.

Equalize once per month myself.

[sjturbo]

Very cool NinerB! I was thinking, do you really need to equalize every 10 to 12 days? I guess that would be based on how much you draw down within that period, correct? Based on that how often would you be "top charging" per MW?