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Author Topic: charge deficit  (Read 4090 times)
bar
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« on: December 09, 2008, 10:18:33 PM »

Hi All

i have 48 volt battery bank 1350 amp hour capacity (C20).

charger is delivering 30 amps (at 240v AC) = 140 amps DC

batteries are only 18 months in service. do not seem to be able to get the batteries fully charged.

when i set DOD at 50% (48.4v) when low point is reached my gen cuts in and runs for about 2.5 hours for bulk charge. this equates to 350 amps. i should be able to get 675amps into the batts. this is almost 25% loss off the top end of the batteries.

i am told this may be charge deficit and may not be recoverable.

currently charging to 58.8v with absorption time of 6 hours - float voltage 53.6v.

anyone any ideas?

thanks

Bar
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martin
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« Reply #1 on: December 09, 2008, 10:26:44 PM »

What sort of batteries are they? - If they're flooded lead acid, it sounds as if they could do with a good equalising charge  to dislodge any sulphation. The other thing to bear in mind is that if you're regularly taking them down to 50%, and you've done that every day for 18 months, they could just be plain knackering out! (for example if you were using "leisure" batteries, they're rated at something like 200 cycles to 50% DOD, so they would probably have died nearly a year ago)
« Last Edit: December 09, 2008, 10:28:19 PM by martin » Logged

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Justme
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« Reply #2 on: December 09, 2008, 10:34:28 PM »

2.5 hour bulk & 6 hour absorption charge sound far to short a time to realy fully charge the bank. I think you should be looking at nearer 10 hours or more. Plus do a equalising charge.

Is the bank a proper deep cycle (forklift) type or some other type?

Justme
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Billy
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« Reply #3 on: December 09, 2008, 10:40:22 PM »

MOTHER OF GOD,

that is a battery bank to kill for, agree with M, need more info, what charger, how you measuring discharge, volts or amp counter?

What is your heavy end discharge rate.

Are they Rolls 5000 per chance?

Speak soon

 Grin
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« Reply #4 on: December 09, 2008, 10:41:34 PM »

The other suspicion I'm getting is about the amperage of the charger - if it's quoted as a "30 amp" charger, that usually denotes the output power - are we absolutely sure it's outputting 140 amps?
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« Reply #5 on: December 09, 2008, 11:08:25 PM »

Hi Bar,

I think you need to tweek the settings on your inverter/charger 2.5h is no where near long enough I don't care how many amps it's putting in. I would say 5 hours for an ordinary charge and a couple extra for an EQ. Also check the SG on all your batteries regularly and note any variations, duff cells will confuse your inverter and make it stop charging early. Also in my experience you'll never achieve a full SG reading like you had with new batteries unless you EQ them for days or have a hydro turbine :-)

Good luck, Paul
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'Off grid' since 1985,  Proven 2.5kW, Proven 6kW direct heating, SMA SI6.OH, 800ah Rolls, 8kW PV ,4xTS45, Lister HR2 12kW, , Powerspout pelton, Stream Engine turgo, 60 x Navitron toobs and a 1500lt store. Outback VFX3048 and 950ah forklifts for backup,
bar
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« Reply #6 on: December 10, 2008, 06:54:09 PM »

hi guys

my batteries are Rolls 5000 series 4 volt units P25. these should do 3000 cycles for 50% discharge. currently charging once every 3 days - should do a week.

have been monitoring sgs and they are between 1250 and 1270 after charge.

charged last night with settings above. total charge time/generator run time 8.5 hours.

i have 2 x trace sw4548E inverters in parallel set to 15 amp each for charging. display shows 15 to 17.5 amps AC in) on both during bulk charge.

will try equalisation charge at weekend and do the sgs. propose equalisation setting of 61.6 volts with absorption time of 4 hours.

any thoughts

cheers

Bar
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northern installer
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« Reply #7 on: December 10, 2008, 07:46:23 PM »

bar,everyone,if you go to www exide.com you will find there are tech manuals for free down load;a mine of information!
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billi
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« Reply #8 on: December 10, 2008, 09:41:36 PM »

Bar do you have a Battery monitor ?  to see DC Ampere

Still Martins question/note  makes sense to me   are you sure its  AC   with your ampere   or only  about 30 A  at 48 DC Volt ?

Billi
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Billy
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« Reply #9 on: December 10, 2008, 09:57:58 PM »

Bar,

Rolls are good batteries for sure, have some myself.

Are the Xantrex totally automatic charging or do you have to set them up for your specific battery bank.

Had to set up my Victron to suit battery bank and if I use two or more then they have to be set up as master and slaves (is that right billi?).  If genny is shutting down early then maybe down to programming fault, possibly wrong battery type or bank size, or just haven't specified long enough bulk charge cycle. 

I don't have any info on the your Xantrex stuff alas.  Edit.  Found some, says the max charge rate of 60amps so the two of them should be 120 max, can't find a manual to check on settings or stuff, sorry.  Sad

Took me ages to wade through set up book on the Victron.

 Grin
« Last Edit: December 10, 2008, 10:07:47 PM by Billy » Logged
billi
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« Reply #10 on: December 10, 2008, 10:33:55 PM »

Quote
as master and slaves (is that right billi?)

Sure Billy thats right  Grin Took me a while as well ...., perhaps even more with the parallel setup

problem is that i have some sort of Alzheimer s   and forget  Grin   if i change something i have to start totally as a beginner  , anyhow  what i remember is that i adjusted my charger to wet cells after my GEL leisure  ones went  kaput

As well i like the Temp sensors , to self adjust charging in cooler conditions

Billi

Rab thats a too hefty bank of a battery  to make jokes and perhaps talk to Rolls as well



« Last Edit: December 10, 2008, 10:38:47 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
bar
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« Reply #11 on: December 14, 2008, 09:34:48 PM »

hi guys

thanks for the thoughts. have been thru quite a lot of the points. can confirm

- inverter/chargers are set up as master and slave with all the right settings.
- inverter/chargers ahve display and all matches with amp readings from generator while charging.
- inverter/charger has error list which does show up any probs. no probs.
- batts are well looked after and topped up
- all connections good
 
Do not know what the settings on the charger are to recognise batteries when charged - have no access. can only think batts (or batt) are not taking full charge. could be rouge cell giving bad reading?? or could be all the batts if not commissioned right???

will have to keep testing.

any ideas on a testing regime from just before charging, thruough charging cycle and on completion of charge???

cheers

Bar



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« Reply #12 on: December 14, 2008, 09:58:37 PM »

Quote
Do not know what the settings on the charger are to recognise batteries when charged - have no access.

Bar  why not contacting your supplier of charger or trace  ....  my charger was set for Gel batteries and i changed it to match the forklift ones  .... perhaps you never charge them full cause your charger thinks of other battery ?


Billi
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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
Billy
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« Reply #13 on: December 15, 2008, 12:37:08 AM »

Bar,

Rolls are good, and normally ok, if you suspect there is a problem, contact supplier re guarantee, (ten years is it not).  Where did they come from, Barden?

Sorry, can't read through the whole lot again but is there a temperature sensor and are the batteries kept hot or cold, don't think it would make that much difference mind.

I think your batteries are seriously under charged by large amount, maybe in excess of 50% undercharging, with losses.  Sounds like not a small fault but major fault or software malfunction  somewhere.  Your Xantrex should be quite capable of charging your bank, it is on the top end but still should be fine.

I have Rolls and the only thing that upsets them is very heavy discharge loads beyond 20% rule.  Causes low voltage shut downs and warnings on inverter/charger even though batteries are near full charge.

How much water have they used in the 18months?

 Huh Sad
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« Reply #14 on: December 15, 2008, 07:23:24 AM »

Morning Bar,

I'm in a bit of a rush right now but there are
settings to alter the charge rates which I'll try and dig out. However if your getting readings of 1250+ on all your cells then altering the settings is unlikely to improve things (unless your hydrometer is wonky) If you have a dud cell it WILL confuse your inverter but with high readings like yours that is unlikely.

Spek to you later, Paul
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'Off grid' since 1985,  Proven 2.5kW, Proven 6kW direct heating, SMA SI6.OH, 800ah Rolls, 8kW PV ,4xTS45, Lister HR2 12kW, , Powerspout pelton, Stream Engine turgo, 60 x Navitron toobs and a 1500lt store. Outback VFX3048 and 950ah forklifts for backup,
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