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Author Topic: Think I've killed my batteries...  (Read 3966 times)
Jonah
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« on: December 12, 2013, 07:51:32 AM »

Hi all, wonder if you can help.

  I moved house 14 months ago and didn't want to sell me off grid kit so packed it all up ready to put on the new house when I get chance.  My batteries were in very good condition and full of charge when I last used them and I've put the charger on them twice just to top them up but when I checked them yesterday they were only showing 28v (48v) and very low on water (took around 1l each) but when I put them on charge they start gassing straight away and will only charge for around an hour (3x @39mins only taking 40 amp/h) plate colour looks good and I've just ordered a hydrometer to check sg but even after 3 charges I can't get it to stay above 46v....  Should I charge it through my inverter or should I connect it up and use it to get it going or could it be the cold temps messing with the voltage as it's been kept outside but in the shade?

Please help a stupid man try and fix 4k worth of batteries ;(

Marc
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Tiff
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« Reply #1 on: December 12, 2013, 08:48:42 AM »

Did any connections get moved/broken/changed during the move?

That's a massive drop in voltage and sounds rather odd.

Maybe some more details of how the batteries are wired might help.

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garethpuk
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« Reply #2 on: December 12, 2013, 09:46:26 AM »

First of all I'm no expert  Grin Are you measuring the voltage across the whole bank and can you take readings on individual batteries or cells? Usually when a battery bank or pack fails its one battery or cell that drags the whole lot down.
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biff
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« Reply #3 on: December 12, 2013, 09:54:51 AM »

Hello marc,
          Just sit down and quietly study the bank and the way that you have reconnected them.Get out yout multimeter and check the voltage in each seperate battery/cell. You might just have a dud or a bad connection towards the far end of the string but you need to check each individual cell/batt.
                                                                              Biff
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Jonah
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« Reply #4 on: December 12, 2013, 12:58:10 PM »

Thanks guys, it's actually 48 batteries in 2 banks to make 48v with around 1100a/h and I've measured across each bank and each battery and even though there are some differences they are pretty much down with the highest voltage showing only 2.00v and lowest @1.93v (so the maths to 46.9 just doesn't work out to me as most were 1.97+)....  I'm hoping it's something to do with the low temp and lack of use so I'll connect it up to my inverter and the house and see how it goes. If at all...

Thanks

Marc
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Jonah
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« Reply #5 on: December 12, 2013, 12:59:06 PM »

Ref reconnecting them, they're in a battery box so no disconnection etc
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oliver90owner
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« Reply #6 on: December 12, 2013, 01:16:05 PM »

As above, but in addition - perhaps disconnecting the parallel connector and charging each string separately might make diagnosis easier.

RAB
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Eleanor
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« Reply #7 on: December 12, 2013, 10:11:21 PM »

Hi Marc, I'm quite intrigued as to how you managed to move 48 2V cells in a box without disconnecting any of them Huh If the cells are showing low voltage I wouldn't discharge them any more. The hydrometer is a good move but at the moment the readings will be low as the cells have just been topped up and the electrolyte needs mixing so you'll have to charge them or shake them. What do you mean that they will only charge for an hour? Is this something to do with the charger settings? Once they start to gas (in a normal situation) they need to go for a few more hours yet. Have you checked the readings with another volt meter? If the cells start to gas after a short time either they are fine and nearly charged or they have lost capacity and charge up very quickly as a result. Hopefully it's the former but if not you'll have some long low current charging sessions ahead to try and recover the situation. When you're charging it's worth checking that each individual cell is charging above the absorption voltage after the charger thinks the bulk charge has finished as any that aren't will lag further and further behind. Anyway, good luck and there are lots of people here who have been in a similar situation and can offer help.
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Jonah
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« Reply #8 on: December 13, 2013, 07:04:16 AM »

Thanks Eleanor, my battery bank is in a large steel battery box so all I've disconnected it the main positive and negative which has a forklift type handle on that use to connect into my solar/genny/inverter junction boxes etc.  I only have my 120amp forklift charger available at the moment which only charges for 40mins before becoming satisfied and switching off, it's recording a voltage or 59.something v at this point but only showing putting in 40ah (I don't expect more in that time I just thought it should run longer.  I think I'll have to connect it to the victron inverter as I can set the amp etc that it'll push in and as you say give it a long and steady charge.  If they're ok I'll make a point of putting my solar back up and promise to look after it better Wink

Thanks all for you help

Marc

Ps, I've used 2different meters, also if they are dead would the plates look normal?
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biff
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« Reply #9 on: December 13, 2013, 10:15:15 AM »

Good morning Marc,
                     120amp forklift charger is a hell of a load and would murder any normal 5kw generator.Its possible that the charger only charges what it thinks the power source can deliver but somethng is not right.Check each individual cell seperatly and look for the one which is dragging the rest down if that is the problem
     Try and avoid using the forklift charger,They are a terrible waste of energy,perhaps once in a blue moon to give the cells a shake up during an equalising charge.
        It is also possible that your forklift charger might be faulty,there is a little control card in them that gets replaced on a regular basis.These same chargers are not fool proof.Meanwhile there is nothing to stop you from using another 40amp charger and seeing if it produces better results.
         Be carefull,
                  Biff
« Last Edit: December 13, 2013, 10:17:22 AM by biff » Logged

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camillitech
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« Reply #10 on: December 13, 2013, 10:52:39 AM »

Good morning Marc,
                     120amp forklift charger is a hell of a load and would murder any normal 5kw generator.Its possible that the charger only charges what it thinks the power source can deliver but somethng is not right.Check each individual cell seperatly and look for the one which is dragging the rest down if that is the problem
     Try and avoid using the forklift charger,They are a terrible waste of energy,perhaps once in a blue moon to give the cells a shake up during an equalising charge.
        It is also possible that your forklift charger might be faulty,there is a little control card in them that gets replaced on a regular basis.These same chargers are not fool proof.Meanwhile there is nothing to stop you from using another 40amp charger and seeing if it produces better results.
         Be carefull,
                  Biff

Methinks Marc is on the grid now Biff, probably with three phase if he can run a 120amp 48v charger  Shocked Perhaps that's the problem, not enough juice to the charger Huh
« Last Edit: December 13, 2013, 10:55:42 AM by camillitech » Logged

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Jonah
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« Reply #11 on: December 13, 2013, 11:24:13 AM »

Cheers guys, my charger is single phase and runs off the lister 7.5kw which does struggle slightly but will hold 110 amps on the charger ok (not happily but still 50hz and 228v) but it gets down to around 70-60 within minutes until it's satisfied. However I am back on grid now so I'll put the Victron in place and run through that and if I can get some juice in the batteries I'll just cut the grid supply to the inverter to cycle the batteries slightly. I can't remember if the inverter does an equalization charge other than that I'll have to get the solar up and run through the midnite solar as I know that does eq charge.

Cheers

Marc
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Bioman
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« Reply #12 on: January 08, 2014, 09:35:09 PM »

have you the option on your charger for Battery desulfator
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Philip R
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« Reply #13 on: January 08, 2014, 10:11:11 PM »

Marc,
You mentioned at the beginning that the cells went low on water. Exposure of the battery plates to air can cause irreversible oxidation of the spongy lead of the negative plates. (Negative plate burnout). I do not believe re-watering and charging will bring them back, but certainly give it a go.

There are many methods of battery charging associated with various best practices, originated in different countries and used by indiginous battery manufactures. My experience was mainly with Lead acid Plante batteries from Chloride and Tungstone (Neither manufacturing in the UK now)

Typical float voltage was 2.25volts per cell, but his will not recharge  or equalise a flattened or unequally charged battery.

Boost charging at C7 (approx 14% Amps of Ah capacity) upto about 2.35 vpc followed by C14 (approx7% Amps of Ah capacity) for a few hours, the cell voltage could rise to 2.5 to 2.6 vpc , however concerted gassing will cause loss of active plate material and shorten the life of the cells. However it should equalise the charge of the cells, also checking the s.g. until it stabilises. We used this in the CEGB in the 1980s and the privatised ESI beyond. Batteries regularly exceeding a 20 year life.

Latter moves to VRLA cells adopted different regimes of management and very short lives.

Whilst charging the batteries, meassure the DC voltage and also the AC across each cell, The ripple content of the AC tells a lot about the cell impedance.

Philip R
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Jonah
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« Reply #14 on: January 08, 2014, 10:19:20 PM »

Thanks Phillip I'll give it a whirl.

Marc
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