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Author Topic: absorption charge time setting  (Read 8621 times)
billi
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« on: August 20, 2009, 09:11:01 PM »

How long do you let a charger stay in absorption charge mode ? Can it harm the battery (flooded wet cells) if too long ?

I should know this by now but , my chargers did decide that themselfs , but now i would like to know more about it

thanks Billi
« Last Edit: August 26, 2009, 12:51:59 PM by billi » Logged

1.6 kw and 2.4 kw   PV array  , Outback MX 60 and FM80 charge controller  ,24 volt 1600 AH Battery ,6 Kw Victron inverter charger, 1.1 kw high head hydro turbine as a back up generator , 5 kw woodburner, 36 solar tubes with 360 l water tank, 1.6 kw  windturbine
Justme
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« Reply #1 on: August 23, 2009, 10:54:09 AM »

I have my bulk phase end at 12.7v ( I was advised to stop at 12.4 for my lead antimony cells but went higher in the end as genny charging costs so much). I have my genny absorb set to manual as I dont think the Victron auto works well. I have it set to 6 hours but as its controlled by the amount of time I have the genny on it wont often get that. I normally run the genny for up to 4 hours on a normal charge & if I want to do a full absorb or EQ then I will do it on a day that I need the genny for other things & do up to 12 hours. I also have the FM80 set to those voltages but the absorb is set to 4 hours. Its very unlikely that the FM alone will ever do 4 hours unless we have a good run of sunny days as it wont hit absorb till late in the day. Yes the bats bubble / fizz quite well but not excessively say like a glass of fizzy drink after its been poured for 5 mins ish but smaller bubbles (like a home brew wine thats going quite well bat the start of the ferment). Yes you can over do it but hard on a big bank like mine (1550ah 5C) with a 120amp charger its hard.

I try to fully absorb weekly & eq monthly but as my EQ settings are the same as my absorb settings a good absorb covers my EQ.
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Navitron solar thermal system
30 x 58mm panel 259L TS
1200watts solar 120vdc
FX80 Solar controller
Victron 12v 3000w 120a
6kva genny
6 x 2v cells 1550amp/h 5C
24 x 2v cells 700amp/h 5C
Total bank 4350 amp/h 5C
billi
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« Reply #2 on: August 23, 2009, 12:05:58 PM »

Quote
I have my bulk phase end at 12.7v
  Hope you mean 14.7 volt   ....
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1.6 kw and 2.4 kw   PV array  , Outback MX 60 and FM80 charge controller  ,24 volt 1600 AH Battery ,6 Kw Victron inverter charger, 1.1 kw high head hydro turbine as a back up generator , 5 kw woodburner, 36 solar tubes with 360 l water tank, 1.6 kw  windturbine
Justme
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« Reply #3 on: August 23, 2009, 01:41:54 PM »

I thought my bats were flat lol........

Dam fingers never do as they are told.

Yeh 14.7v. Now remembering back it was set at that when

a, I had slightly thinner cable (slight V drop)
b, to allow for the slight volt reading dif between the Victron & a good meter (0.1v)
c, the FM has an adjustment you can change to tweak the V to meet the same reading as a good meter & account for the v drop to the controller so that was set slightly lower.
d, the bats are external & always in the shade so a slightly higher v is ok ( I suppose I could buy the sensor for the Victron & FM80)

Now I have much bigger (120mm2) cables the v drop is not measureable even when I have tested it under load (not full load as I dont often use it to the max).
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Navitron solar thermal system
30 x 58mm panel 259L TS
1200watts solar 120vdc
FX80 Solar controller
Victron 12v 3000w 120a
6kva genny
6 x 2v cells 1550amp/h 5C
24 x 2v cells 700amp/h 5C
Total bank 4350 amp/h 5C
noelsquibb
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« Reply #4 on: August 23, 2009, 08:19:05 PM »

I know very little about batteries but was recently sent a link to the battery university -

http://www.batteryuniversity.com/

Im still none the wiser  Sad

noel
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mmmmm,  gravy
billi
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« Reply #5 on: August 26, 2009, 12:45:49 PM »

Thanks Noel and even a German version available  Grin

Anyhow my Battery now everyday gets into absorption  charge  Tongue  set the absorption time to three hours  and hope that is fine for the summer

I think i reduce the charging volt to  about 29.2 Volt

Billi

And i just double-checked  with one Multimeter
the charge controller show  29.7 volt ( temp regulated ) but the Multimeter only 29.4  so connected a second Meter and  Shocked   different readings  so my always used meter seems wrong


* absorbtion.jpg (117.2 KB, 850x638 - viewed 1015 times.)
« Last Edit: August 26, 2009, 01:17:11 PM by billi » Logged

1.6 kw and 2.4 kw   PV array  , Outback MX 60 and FM80 charge controller  ,24 volt 1600 AH Battery ,6 Kw Victron inverter charger, 1.1 kw high head hydro turbine as a back up generator , 5 kw woodburner, 36 solar tubes with 360 l water tank, 1.6 kw  windturbine
peter999
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« Reply #6 on: August 26, 2009, 02:01:06 PM »


 General rule of thumb for wet cells is bulk charge up to 14.4v aborption from 14.4v untill current draw drops right down and then float charge will hold the battery voltage at 13.2ish volts  equalization charge approx 15.2-5v for about 4 hrs.

The time the batteries are in absorption charge will vari as the charge voltage is held steady and the current is reduced untill any current draw raises the voltage above the absorption voltage at which point it goes to float voltage.

if you have a large battery bank you may never get out of absorption stage!!

this is why you battery bank size should be matched to your current draw demards and your charging sources  charging currents.

regards Peter
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billi
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« Reply #7 on: August 26, 2009, 02:08:27 PM »

Quote
General rule of thumb for wet cells is bulk charge up to 14.4v aborption from 14.4v untill current draw drops right down and then float charge will hold the battery voltage at 13.2ish volts

But that is at at 25 Temperature  should be higher in colder conditions and lower in warmer , just in case someone has different temps then 25

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1.6 kw and 2.4 kw   PV array  , Outback MX 60 and FM80 charge controller  ,24 volt 1600 AH Battery ,6 Kw Victron inverter charger, 1.1 kw high head hydro turbine as a back up generator , 5 kw woodburner, 36 solar tubes with 360 l water tank, 1.6 kw  windturbine
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« Reply #8 on: August 26, 2009, 04:30:52 PM »

 
  general rule of thumb  @ 25Degres Grin
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Outtasight
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« Reply #9 on: September 10, 2009, 02:51:43 AM »

If you can't monitor the current to see when it bottoms out Yuasa recommend an absorption time that is half that of the time it took to get to the absorption voltage from whatever level it was at when you started charging.  So if it took 10 hours to get to 14.4V then let it simmer for 5 hours.  This assumes a small charge current compared to the bank capacity though (C/10 or less).  If you've got loads of current available (C/4 or more) the voltage will jump up more quickly giving a false impression of the bulk charge time.
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