AGM Batteries

hi all, accidentally left Fridge on 12 volt and ran batteries flat for (weeks) of course they no longer hold charge ( solar) for very long ...have I stuffed them (2)... only 2 years old ... thanx .....signed.... forgettful
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Reply By: Member - Bruce C (NSW) - Sunday, Jan 19, 2014 at 13:27

Sunday, Jan 19, 2014 at 13:27
Hi Bazz,
I had done that to an AGM also and I figured I would charge it and see how it went. It worked. Life span may well be compromised but it may not be a dead loss.

What is done is done and any damage you will have to live with I guess, however, just give it a good charge and see how you go. If you get another three years out of it that will be something, you may get longer.

Cheers, Bruce.
At home and at ease on a track that I know not and
restless and lost on a track that I know. HL.

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Reply By: Member Andys Adventures - Sunday, Jan 19, 2014 at 14:03

Sunday, Jan 19, 2014 at 14:03
Hi Bazz,
I left my truck at a friends place to fly home for 2 weeks and left the solar panels out to charge the batteries as I left the fridge and freezer on 2x 40 lt engels. Got back to find the batteries where at 10.2v, the solar panels were in the shade most of the day. It took 2 days charging them but they have responded and now hold a charge of 13.4v. I thought they were stuffed but I might get a few more years out of them.
Cheers Andy
P.S. Take a picture of the batteries and leave it in on the dash in your tug as a reminder.
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Reply By: Allan B (Member, SunCoast) - Sunday, Jan 19, 2014 at 14:10

Sunday, Jan 19, 2014 at 14:10
Bazz,
If they are dead flat there can be a problem with a 'smart' charger as most will not begin to charge unless the charger can 'see' a few volts in the battery.
A way to overcome this is to temporarily connect a good battery in parallel (+ to +, - to -) then connect and fire-up the charger. Once charging commences, disconnect the 'good' battery whilst keeping the charger connected to the flat batter. Charge each flat battery in turn.
As Bruce said, worth a try.
Cheers
Allan

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Follow Up By: olcoolone - Sunday, Jan 19, 2014 at 14:20

Sunday, Jan 19, 2014 at 14:20
Or use a battery charger with a supply function and leave it on for a few hours, we do this in our workshop when we get dead flat batteries and the Cteks will not see the battery..... Just switch the battery charger over to supply mode and all is good, after a few hours we switch the battery charger back to normal and charge the battery.
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Follow Up By: Member - Frank P (NSW) - Sunday, Jan 19, 2014 at 14:23

Sunday, Jan 19, 2014 at 14:23
Some chargers have a "wake-up" first cycle that attempts to bring an over-discharged battery back to life before proper charging commences. I think Ctek is one.

Cheers
FrankP

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Reply By: Member - Frank P (NSW) - Sunday, Jan 19, 2014 at 14:31

Sunday, Jan 19, 2014 at 14:31
If they were like that for weeks they are probably well and truly sulphated. If you can wake them up as others have suggested above, you may get something out of them. Maybe contact the manufacturer, tell them what has happened and ask them for any suggestions.

eg you normally don't equalize (equalisation is a controlled overcharge for a limited period) VRLA batteries, but in this case a carefully controlled and perhaps limited equalisation charge might help with the sulphation - ask the manufacturer.

Good luck
FrankP

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Reply By: The Bantam - Sunday, Jan 19, 2014 at 14:54

Sunday, Jan 19, 2014 at 14:54
This is all a matter of how lucky you have been.

it is possible that.

The battery is comprehensively snotted and beyond help.

The battery will come back just fine with a good stiff charge

or
anywhere inbetween.

it will vary a great deal duse to a number of factors.

worth giving a few things a red hot go......but dont be disapointed if you end up with a plastic box full of scrap lead and acid.

cheers
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Follow Up By: abqaiq - Sunday, Jan 19, 2014 at 21:49

Sunday, Jan 19, 2014 at 21:49
If it's a Valve Regulated Lead Acid [VRLA] battery with the little charge indicator "eye" and the eye is gone clear of yellow Do not try to recharge [jump starting, etc.] without checking with the manufacture. An input of power may cause a reaction >high heat and perhaps an explosion. I was just reading up on this for a presentation to the guys and noted that potential. Read up on it in a technical article on the web just in case they asked the why not?

Abqaiq
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Reply By: Luke2 - Sunday, Jan 19, 2014 at 22:00

Sunday, Jan 19, 2014 at 22:00
A fridge will normally cut out once voltage drops to 10 or 11 volts (depends on the brand and model) so unlikely a fridge will run a battery right down and damage it. An interior light will run a battery right down to nothing but not usually a fridge.
Charge it up and see what happens. could be good as gold.
AnswerID: 524758

Follow Up By: Brian 01 - Sunday, Jan 19, 2014 at 22:17

Sunday, Jan 19, 2014 at 22:17
10 volts is well below dead flat for a 12v battery, and if left in that state for more than a day or two, the chances of recovery become slim.
If the fridge is a 3 way, then there will be no cut out, it will draw the battery down to zero.
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Follow Up By: The Bantam - Sunday, Jan 19, 2014 at 23:50

Sunday, Jan 19, 2014 at 23:50
Not all fridges have voltage cut outs and will continue to rum well below what is healthy for a battery.

cheers
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Follow Up By: bazz - Monday, Jan 20, 2014 at 07:45

Monday, Jan 20, 2014 at 07:45
thanx for the input tried recharging , they just rundown real quick , live in learn I guess, cheers
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Follow Up By: Member - Frank P (NSW) - Monday, Jan 20, 2014 at 09:49

Monday, Jan 20, 2014 at 09:49
Bazz,

To guard against future similar occurrences you could install a voltage sensitive relay such as this one to operate as a low voltage cutout.

Install it so that no loads are drawn direct from the battery, all loads are drawn through the relay. That way, if you forget something or there is a fault, when the battery gets down to a voltage you can set, say 11 volts, it will isolate the battery and not flatten it any further.

It imposes a slight load on the battery to hold itself on, 0.03amp (30 milliamps) and has a 10 amp limit. If your regular loads total more than that you will need to search for a different product.

Cheers
FrankP

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Follow Up By: bazz - Monday, Jan 20, 2014 at 19:40

Monday, Jan 20, 2014 at 19:40
yes thanx for the idea
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Follow Up By: Nutta - Tuesday, Jan 21, 2014 at 22:09

Tuesday, Jan 21, 2014 at 22:09
I got the same thing from Jaycar for $40, works a treat!
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Reply By: Iza B - Monday, Jan 20, 2014 at 08:27

Monday, Jan 20, 2014 at 08:27
No battery likes that kind of abuse. You say you can get a charge in but the batteries no longer seem to have any capacity. I suspect you have just paid for a rotten experience.

Iza
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Reply By: Member - LeighW - Monday, Jan 20, 2014 at 12:52

Monday, Jan 20, 2014 at 12:52
Try cycling them a few times they might come good.

Also if you can get access to a regulated power supply try giving them
a boost charge at around 15.5V for say 30 minutes, it might stir up the
electrolyte a little and help de suplhate them. You will need to keep a close eye on them though.

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