Absorption times for FLA’s?

jeffkruse

I was getting low SG readings on my Deka FLA’s until I did a 6+ hour long EG at 2500W.

I use all the Xantrex default settings for charging my batteries but that doesn’t seem adequate to keep my batteries charged even though the CC would go into float mode almost every day.

The company I purchased everything from recommended that I increase the Absorb time.

Any issues with that? Thoughts?

BB.

Re: Absorption times for FLA’s?

Are the SG levels consitent across cells and batteries (within 0.030 or less)? (batteries that need equalization may have out-of-balance cell by cell SG)

What is the highest SG readings you have seen, vs the average "charged" battery state? (when new, what did the batteries read. Older, sulfated batteries will read low)

Are you temperature correcting your readings to ~77F? (hot batteries read lower).

What was the SG reading when new> (frequently, batteries used in hot climates are filled with lower SG electrolyte for longer life).

Are you needed to add water every month or three? (batteries that are well charged/equalized will generally use some water--batteries that use a lot of water are probably over charged)

Is there a pattern with SG levels and/or water consumption (some batteries always high, others always using a lot of water, others not)? (series parallel wiring problems; loose connections, bad wiring, one battery with open/shorted cell)

-Bill

PS:

What is the voltage the batteries are reaching during absorb/equalize. (low voltage, slow charging, perhaps not fully charging)

What is the battery temperature? (cold batteries need higher voltages)

Is the charge controller equipped with a remote battery temperature sensor (sometimes controllers read "hot" and will be a few tenth's of a volt below "optimum" battery charging voltage)

jeffkruse

Re: Absorption times for FLA’s?

Are the SG levels consistent across cells and batteries (within 0.030 or less)? I would say yes now (its only been two weeks since the 6+hour EQ)What is the highest SG readings you have seen, vs the average "charged" battery state? (when new, what did the batteries read. Older, sulfated batteries will read low) The readings were lower than expected when I got them so I though the meter was bad and then ordered a good SG meter.
Are you temperature correcting your readings to ~77F? (hot batteries read lower). Yes, the SG meter has a good thermometer built in and it shows the corrections to add.What was the SG reading when new> (frequently, batteries used in hot climates are filled with lower SG electrolyte for longer life). These were not filled with lower SG electrolyte
Are you needed to add water every month or three? (batteries that are well charged/equalized will generally use some water--batteries that use a lot of water are probably over charged)
These are 3 months old and I have added 1 ½ Gallons but I also filled them about ¼ - ½ inch higher than they were when I got them. The level is just touching the bottom of the “chimney”.
Is there a pattern with SG levels and/or water consumption (some batteries always high, others always using a lot of water, others not)? (series parallel wiring problems; loose connections, bad wiring, one battery with open/shorted cell) All connections are good, I even measured the voltage drops.
-Bill

PS:

What is the voltage the batteries are reaching during absorb/equalize. (low voltage, slow charging, perhaps not fully charging) Not sure, I am not home at that time.What is the battery temperature? (cold batteries need higher voltages) The temp probe shows that they are 90 degrees. The outdoor temp is around 86 degrees every day.
Is the charge controller equipped with a remote battery temperature sensor (sometimes controllers read "hot" and will be a few tenth's of a volt below "optimum" battery charging voltage) Yes

Cariboocoot

Re: Absorption times for FLA’s?

How long should absorb time be? That is a good question. The Outback MX60 determines this by counting up the minutes from when Bulk charging starts until Absorb Voltage is reached, with programmable min/max times. But is that really optimum? Good question too. If you have a battery meter you can get a more accurate view of how charging is going. As Bill pointed out, you have to get some "baseline numbers" for your particular battery bank and compare future readings to that.

Maybe we should make up a "rule of thumb" about this, based on people's experiences. Something like "1 hour per 100 Amp/hrs of battery capacity". (Subject to refinement and correction and probably ridicule as well.)

Dave Angelini

Re: Absorption times for FLA’s?

I use some of what the guy's here have suggested but I also use the time of day that the battery goes to float for troubleshooting and optimizing.

The other thing is there are bugs in the XWCC that have to be accounted for. The new revision 5 of firmware is not out yet but it fixes them.

Yes, you should tweak your absorb time up! What revision do you have and what time are you floating. Also what is the the XWCC logging for KWH per day?

RCinFLA

Re: Absorption times for FLA’s?

Pretty sure the XW series has a current decay bulk termination as well as a timed termination. Normally you should set for current decay termination (>5% current of phase 1 current limited charge). This is the best way to terminate bulk (absorbtion) mode. Use the timer mode as a safety termination if something goes bad with one of the batteries that causes the bulk current not to drop normally then timer will invoke the abort to avoid continuous bulk mode.

To detemine the proper time, check the time length the bulk current in phase two of charging. When it shows it has dropped to >5% of phase 1 current limit this will be the normal bulk phase 2 duration. It will likely get longer as batteries age. I would double this time for safety timeout setting.

blackswan555

Re: Absorption times for FLA’s?

Advice given to me from a Rolls tech.

Unless you have way to many panels and a very low consumption it is best to absorb for as long as possible from PV, he recommended either setting absorb time to longer than the day, Or as I do, set float to same as absorb v,
Keep and eye on your water usage and if it is high, Back off a little on the voltage, But once you find your sweet spot on v vs water usage, should extend your required EQ time by months,
(Above only applies to FLA`s)

Have a good one
Tim

jeffkruse

Re: Absorption times for FLA’s?

I think that’s good advice. For me, right now there is no reason I can’t increase the absorb time to max. However, I did want to know how much “extra” power I had so maybe I could use it for something other than lightly overcharging the batteries.

Dave Angelini

Re: Absorption times for FLA’s?

If you just set the absorb to what ever number of hours you feel like you will just use more water. At this point you should just buy AGM's or Gels because you are giving up the best attribute of the battery type you have.

The ability to measure specific gravity give you all the data you need to fully charge your battery and not use more water than needed. I think alot of people have trouble with batteries because they are using so much water they forget to top up one time and expose the plates. After you do that you have lost capacity and problem cells start showing up.

Fabian

I am planning to buy a Makeskyblue 60a mppt charge controller. I was told that it comes with a 1 hour preset absorption mode that cannot be change . Would this be sufficient to fully charge FLA and SLA batteries at any size battery bank?
My current bank size is 24v SLA 380ah

BB.

Looking over the specifications for the controller:

https://www.makeskyblue.com/60a.html

I believe it would not be a good choice for vented lead acid storage batteries. The charging voltage(s) set point(s) are, in general, too low for for proper bulk/absorb charging and event lack of Equalizing Charging voltage for these types of batteries (typical flooded cell lead acid storage batteries charge at around 14.75 volts and equalize at 15.0 volts or higher).

For AGM/GEL batteries, the voltage settings are better. Although, if Absorb is limited to 1 hour--That is not great either (typically Absorb is 2 hours for moderately cycled battery, and 4-6 hours for a deeply cycled lead acid battery bank).

-Bill

Estragon

IMHO, 1hr may not be long enough. If stuck with such a controller, I'd be tempted to increase absorb (flooded only) and/or float voltage to compensate, and/or use an alternate charging source to do a longer absorb periodically (eg weekly).

I'd like to be *able* to set a 1hr absorb if that's what makes for happy batteries, but I'd want the ability to go longer. If not stuck with it, I personally wouldn't buy it.

Fabian

Would it be appropriate for sealed led acid that normally takes a lower voltage charge?

If not , would you recommend the epever/eposolar mppt brand then or which other Chinese brand would be more appropriate to use?

BB.

I don't have any recommendations... (added: for charge controllers)

-Bill

Estragon

I wouldn't increase absorb voltage beyond manufacturers spec for a sealed battery. I have no experience with Chinese controllers.

Fabian

So would you say 1 hour would be appropriate for an sla battery then?
Bulk charge to 28.8v and absorb at 28.8v for 1 hour before switching to float at 27.6v?

Estragon

Maybe, or maybe not. What are the manufacturers recommendation for your specific battery?

Fabian

Float charge 27.4v at room temp. I don't see any setting for bulk or.absorb.

jonr

IMO, 1 hour absorb will be too short for good battery life.

Estragon

There wouldn't be a voltage for bulk, but maybe a current spec. I'm surprised there isn't a voltage spec for absorb though, as some sealed batteries tend to be sensitive to high voltage overcharging. Too high voltage can make them gas and vent; not good for sealed batteries.

mike95490

Fabian said:

I am planning to buy a Makeskyblue 60a mppt charge controller. I was told that it comes with a 1 hour preset absorption mode that cannot be change . Would this be sufficient to fully charge FLA and SLA batteries at any size battery bank?
My current bank size is 24v SLA 380ah

NO !

1 hour is not enough for a deeply cycled battery and you will destroy your battery bank with 1 hour absorb.

Fabian

Any ideas on another cheap mppt which would give me at least 2hr absorb time?

mike95490

https://www.morningstarcorp.com/products/sunsaver-mppt/  is one II own, and use, and like

out host has a less expensive one,

https://www.solar-electric.com/victron-energy-bluesolar-mppt-75-15-charge-controller.html

 not sure what it's specs are.

mcgivor

The Makeskyblue manual consists of 4 pages, this has got to say something about overall quality, it will do what it's supposed to do, unfortunately though, what it's supposed to do is make money for the manufacturer. 

Fabian

any thoughts on the epever/epo solar or the new edition that they has which is the epever triron?

mcgivor

Fabian said:

any thoughts on the epever/epo solar or the new edition that they has which is the epever triron?

Looking at the manual it appears to be quite sophisticated for its price ~$110, has a 3 hour absorption, remote temperature sensor which is good, PC connectivity, clock with timer functions and more, much better than the Makeskyblue in terms of features. Have never used one so can't comment on performance, but if budget is the limiting factor it seems a reasonable choice, on paper at least. Review wise is hit and miss, but that could be said for any product.

jonr

The Victron BlueSolar 75V/15A manual says this, which is vague but sounds reasonable:

"When only shallow discharges occur the absorption time is kept short in order to prevent overcharging of the battery. After a deep discharge the absorption time is automatically increased to make sure that the battery is completely recharged. Additionally, the absorption period is also ended when the charge current decreases to less than 1A. 

Given the cost, hassles and rapid decline of improperly charged batteries, my generic advice is to not go cheap on charge controllers.

Photowhit

jonr said:

Given the cost, hassles and rapid decline of improperly charged batteries, my generic advice is to not go cheap on charge controllers.

I agree, I think it's important to note that while Victron is not a big supplier of charge controllers in the US they are a major player in The European market. I don't think they would be considered a 'cheap' charge controller. 

While I think this is fine and might meet your needs it's always nice to have a little room to grow. I don't know enough about @Fabian system to know if a 15 amp CC would be large enough currently. That will handle about 200 - 300 watts of panels at 12 volts. I did NOT read the manual so I don't know if it can be over paneled safely.

Fabian

> @mcgivor said:
> Fabian said:
>
>
> any thoughts on the epever/epo solar or the new edition that they has which is the epever triron?
>
>
>
>
>
> Looking at the manual it appears to be quite sophisticated for its price ~$110, has a 3 hour absorption.


Which one has the 3hr absorption time. The epever regular one or the triron?

mcgivor

Fabian said:

> @mcgivor said:
> Fabian said:
>
>
> any thoughts on the epever/epo solar or the new edition that they has which is the epever triron?
>
>
>
>
>
> Looking at the manual it appears to be quite sophisticated for its price ~$110, has a 3 hour absorption.


Which one has the 3hr absorption time. The epever regular one or the triron?

The triton here's the pdf manual 

mike95490

A rule of thumb that is a good point to start with (and what the PT-100 controller does)

is to time the amount of time spent in BULK and use that same time for Absorb.  90 minutes or 4 hours,

Absorb time will vary, depending on the depth of the batterys last discharge.   Some controllers with an

add-on current meter (Midnight Solar Whiz-Bang-Jr) measures the BATTERY charge current, and when that

drops low, terminates Absorb.   Simply measuring controller output current can mislead you, if any loads are

running and the controller is powering them AND charging batteries.

http://www.magnum-dimensions.com/pt-100-mppt-charge-controller