2nd hand AGM - How to recondition?

Submitted: Tuesday, Apr 08, 2014 at 20:02
ThreadID: 107151 Views:5270 Replies:13 FollowUps:10
This Thread has been Archived
Hi all

Today I went and picked up a Ritar(?) 100ah agm battery from a guy who was selling it through Gumtree. I plan on using it as my Aux batt on a hiace campervan I'm building.

The battery was housed in one of those battery box's with cigarette lighter outlets and a few gimicky LED battery meters ect. He always had it hooked up to a 40w solar panel whenever he used it and (according to him) only used it for camping lighting and to charge phones, computers, ect. He mentioned it's around 9 months - a year old and hadn't used it in about 3 months.

I brought it home and threw the multi meter onto it - Less than 2 volts!!

I'm no expert on agm's but I assume having it drained that low can't be good for the battery.

I have a cheap car battery charger that charges 11.5v @ 2.5amp, should I hook it up to this and let it sit for a few days? Or hook it up to my hiace alternator and let it idle for a few hours?

What's the best way to go about 'reconditioning' the battery back to normal?

Also, worst case scenario it was drained completely flat like this a few times, how bad could the potential damage be? Throw away type damage?

Cheers,

Damien
Back Expand Un-Read 0 Moderator

Reply By: Member - Toyocrusa (NSW) - Tuesday, Apr 08, 2014 at 20:56

Tuesday, Apr 08, 2014 at 20:56
I have a 100ah AGM that I took out of my van about a 9 months ago. It is now 5 years old and sitting on rubber, has not been charged in that time and is still 12.8v. It's a Ritar brand as well. Regards, Bob
AnswerID: 530130

Follow Up By: neimad19 - Tuesday, Apr 08, 2014 at 20:59

Tuesday, Apr 08, 2014 at 20:59
Hmm that seems a worry for my case. Do you know if it's unusual for a AGM battery to be discharged all the way down to 2v?
0
FollowupID: 812998

Reply By: neimad19 - Tuesday, Apr 08, 2014 at 21:48

Tuesday, Apr 08, 2014 at 21:48
I went ahead and put the sla charger on it as that really is my only option aside from wiring it to my car alternator.

It started off at about 2v.

After 2 hours of charging I took the charger off, let it sit for a few minutes and the voltage read 4.5v

If anyone has any experience with deeply discharged AGM batteries I'd love to hear how i turned out!

Cheers,

Damien
AnswerID: 530133

Reply By: The Bantam - Tuesday, Apr 08, 2014 at 22:13

Tuesday, Apr 08, 2014 at 22:13
If its reading 2 volts ya chances are slim....very slim.

If you go to the right place you might get money for lead scrap.

Most batteries will not recover from being that deeply discharged.

This charger that charges at 11.5 volts....um that is not going to charge any 12 volt battery..have you got the figures right?

Cheers
AnswerID: 530136

Follow Up By: neimad19 - Tuesday, Apr 08, 2014 at 22:23

Tuesday, Apr 08, 2014 at 22:23
Doh! Yeah, 12.5v is the chargers voltage.

This is definitely not good news :S Do you think hooking it up to the alternator would help?

0
FollowupID: 813005

Follow Up By: The Bantam - Friday, Apr 11, 2014 at 08:08

Friday, Apr 11, 2014 at 08:08
Slow and steady will get the job done if at all..something under 5 amps.

By the same token a realy small charger may not aven have enough to overcome the quite large charging losses that will be involved.

Most of the smart chargers wont even touch a battery that flat.

So you will need a dumb charger.....

I would only be doing it when you can be arround to keep an eye on it.

Now here is another thing....batteries like that when run realy flat can develop charge resistance, this may require a higher voltage in the 15 or 16 volt range to get em started...and then only for sufficient time to get em started then back to normal charging voltages.



Yeh...mate a real lottery.

When ever speculating in used batteries...take a volt meter at least, if it don't read 12 volts or better unloaded it aint good..if its under 10 volts unloaded its pretty well a lost cause.

cheers
0
FollowupID: 813200

Reply By: Nomadic Navara - Tuesday, Apr 08, 2014 at 22:31

Tuesday, Apr 08, 2014 at 22:31
You may be able to bring it back up but it's a long shot. Your charger will not give it much charge at first so it will take many days to give it any sort of charge. Batteries that have been flattened should only be given a low current charge until they come up.

This charger that only puts out 11.5 V puzzles me. What was it designed to charge? With a voltage that low it will not bring the batery u to full charge. After a week or so you will be able to put it on a regular charge and bring it up to full charge (perhaps if you are lucky.)
PeterD
Retired radio and electronics technician

Lifetime Member
My Profile  Send Message

AnswerID: 530138

Reply By: neimad19 - Tuesday, Apr 08, 2014 at 22:45

Tuesday, Apr 08, 2014 at 22:45
EDIT: I meant to write 12.5v not 11.5v
AnswerID: 530139

Reply By: Sand Man (SA) - Wednesday, Apr 09, 2014 at 07:37

Wednesday, Apr 09, 2014 at 07:37
Damien,

Ignoring the fact that the battery is probably cactus, the charger is also not putting out enough voltage, or current.
To charge an AGM you need around 14.2v. Charging at 2.5a, the battery will take forever to reach full capacity even if healthy.
A smart charger that has a maintenance mode may recover the battery, but I doubt it.
10.4 volts is dead flat and after a good charge, the battery should be sitting at 12.8v.
A charger outputting 15 amps is a good starting point and it should be a multi-stage charger to charge the battery properly and maintain it.

If the battery has had even a few total discharges, it may beyond recovery. If the plates have calcified to the extent that a "maintenance" charge won't recover it, then it is a throw away.
Take it to a battery place and have them check it. They should do this for no cost and with no obligation to purchase a new battery from them.

Sorry for the bad news.
Bill


I'm diagonally parked in a parallel Universe!

Member
My Profile  My Blog  My Position  Send Message

AnswerID: 530143

Follow Up By: - Johny boy (NSW) - Wednesday, Apr 09, 2014 at 08:27

Wednesday, Apr 09, 2014 at 08:27
Sand Man just saved me the time to write pretty much exactly the same thing ,so I will agree and second his comments!

Good Luck .
0
FollowupID: 813015

Follow Up By: John and Regina M - Wednesday, Apr 09, 2014 at 08:53

Wednesday, Apr 09, 2014 at 08:53
Sandman
Why should they check the battery for no cost?

They may, but they are perfectly entitled to charge for their services. I respect this option.
1
FollowupID: 813016

Follow Up By: pop2jocem - Wednesday, Apr 09, 2014 at 09:55

Wednesday, Apr 09, 2014 at 09:55
"Why should they check the battery for no cost?"

Simple good business practice. If the battery is cactus, and I suspect with a resting voltage of 2v it is, the guy is going to possibly buy a battery for his camping needs.
The Battery World that I have done business with has never charged for taking maybe 5 minutes to put a gauge on a battery for me or any of my family or acquaintances.

As far as the possibility of recovering this particular battery I think the chances have been pretty well covered but I guess there is nothing to lose by giving a it a shot. I wouldn't try the car charging system though. You could be up for some new components. A multi stage charger would be my choice.

Cheers
Pop
1
FollowupID: 813022

Follow Up By: rooster350 - Wednesday, Apr 09, 2014 at 10:29

Wednesday, Apr 09, 2014 at 10:29
I had 2 100ah d/c batteries tested by Battery World in Darwin for no cost , they were pleased to be asked to do the the job because it would mean a sale if the batteries were faulty, fortunately for me they were o.k.
0
FollowupID: 813026

Follow Up By: Member - Toyocrusa (NSW) - Wednesday, Apr 09, 2014 at 10:33

Wednesday, Apr 09, 2014 at 10:33
Have to agree with you there Bill. It is just plain good business practice to not charge. Even if the owner does not buy a battery off you, they will still tell their friends and eventually someone comes back to buy. Regards,Bob
0
FollowupID: 813027

Follow Up By: get outmore - Thursday, Apr 10, 2014 at 07:13

Thursday, Apr 10, 2014 at 07:13
To check the battery it needs to be charged
0
FollowupID: 813098

Reply By: MEMBER - Darian, SA - Wednesday, Apr 09, 2014 at 15:29

Wednesday, Apr 09, 2014 at 15:29
I think Sandy's 'should' comment is in the context of...'that's what many place do'.... I was at a Century dealer's state warehouse a few years back and they offered to test a battery for me, no cost no obligation..... its a very quick and cheap task for them...... and surely an aspect of modern marketing. I was at BigW today - my wife and I handed over our BigW specs for a 'service' - check the screws, adjust the frame and fit new nose rests - no charge.
AnswerID: 530170

Reply By: Member - Greg T1 (QLD) - Wednesday, Apr 09, 2014 at 20:44

Wednesday, Apr 09, 2014 at 20:44
Hi Damiem,
An AGM battery is designed to go from full charge to fully discharged many times with no detrimental effect to the battery. To recharge you would need to use a smart charger as an AGM needs 14.2 volts or there abouts I believe.
My suggestion would be to go to www.sidewinder.com.au as Derek Bester who is an auto electrician and writes articles for exploroz is an expert on these batteries.
I have a 120amp AGM battery that I bought from Derek 6 years ago and although I have never fully discharged it, it will sit in my workshop for months at a time and still read 12.95 volts.
Greg
AnswerID: 530190

Follow Up By: Alloy c/t - Thursday, Apr 10, 2014 at 11:11

Thursday, Apr 10, 2014 at 11:11
Wrong ,Wrong + Wrong ,, you will kill ANY battery quickly if you fully discharge "many" times ,,,, quite simply the original poster was dudded big time , 2v == one totally stuffed battery.
0
FollowupID: 813124

Reply By: Member - Phil G (SA) - Wednesday, Apr 09, 2014 at 22:17

Wednesday, Apr 09, 2014 at 22:17
When a battery has been deeply discharged (I expect by having something powered off it when stored), it takes a huge effort to get it working again. The internal resistance becomes very high, so the battery will take little charge initially. If you hook it up to your car's alternator, it's unlikely to take much charge, because I expect it has been 2volts for quite a while.

If you hook up a normal battery charger, they usually cut out when they detect the high resistance. What I'd normally do, is hook the battery up to a 13.8 volt power supply and let it sit for a week hooked up to get some charge back into it. Then see how it goes on a multistage charger. If the voltage is OK, then try running a camping fridge off it and see what happens. If the voltage drops off pretty soon, the battery is no good, and you have wasted your money. If the fridge works OK for say a day, then keep the battery fully charged and use it.
AnswerID: 530195

Reply By: Member - John (Vic) - Thursday, Apr 10, 2014 at 00:09

Thursday, Apr 10, 2014 at 00:09
Take it back to the bloke you bought it off and tell him it's knackerd and you want your dollars back.
If it's a year old he can then take it back to where he bought it and try for a warranty claim.
Problem solved for all.

VKS737 - Mobile 6352 (Selcall 6352)

Lifetime Member
My Profile  My Position  Send Message
Classifieds: Water Tank 55 Litre

AnswerID: 530199

Reply By: Member - Boobook - Thursday, Apr 10, 2014 at 09:13

Thursday, Apr 10, 2014 at 09:13
If you own a boat that doesn't have an anchor you're in real luck.

AnswerID: 530216

Reply By: Angryz - Thursday, Apr 10, 2014 at 17:43

Thursday, Apr 10, 2014 at 17:43
Rule of thumb to completely charge a battery is you should use a charger that is 10% of the amp hr of the battery. So to charge a 100 amp hr battery you would need a 10amp battery charger. Better chargers even come with a rejuvination setting that is well worth using even on a good battery.
If in doubt take it to a battery supplier like R&J Batteries. They can charge & test it for you.
AnswerID: 530254

Reply By: neimad19 - Saturday, Apr 12, 2014 at 20:19

Saturday, Apr 12, 2014 at 20:19
Thanks so much for all the help!

Today I finally contacted the guy and got my $$ back. At least I learnt something valuable out of all this;

Buy new batteries only!!

Damien
AnswerID: 530423

Sponsored Links

Popular Products (13)