Recharging a Flat Deep Cycle Battery, 12V 80Ah

[lee]

Hi ppl
My Deep Cycle Battery, 12V 80Ah in my Popup Camper has gone very flat and doesnt seem to be recovering.

Anyone have a good solution to recharge them?
I think it might be stuffed?

Thanks Lee

[moeee]

I guess you gotta work out why its not charging.
Is the battery over 5 years Old?
Do you know why it went flat?
Have you checked it with a Voltmeter and a hydrometer?
Is your battery Charger actually pumping current through it?

[lee]

Hi moeee
its only about 3-4 years old
left it in the camper and didnt have the charger on over winter
was connected to a brake controller that draws a few milliamps when "off"
ijust didnt get around to installing the physical on off switch
(costly forgetfulness i think)

had only 3-4v initially.
i have been charging it for about 12 hours now and its come up to 9v.
i will leave it charging for a few days and check, then leave it sit a while and see what it drops to.
is a fully sealed unit.
charger is supplying a few amps

if i am lucky, (very lucky) it might just come up but i doubt it will have a good capacity anymore.

maybe a good idea to have a small 5w or so solar panel trickle charging it in future.

[moeee]

Sounds like its one of them gel-cells.
If it is, maybe you could have a stab at buying some battery acid.
Get yourself a syringe,I'ld lend you mine but if it you never know what you might catch.
Chuck in about 20 mil of acid if you can work out how to remove the vent covers.
If it is a wet cell, then I'll just get back in my Box

[Joey]

Hi ppl
My Deep Cycle Battery, 12V 80Ah in my Popup Camper has gone very flat and doesnt seem to be recovering.

Anyone have a good solution to recharge them?
I think it might be stuffed?

Thanks Lee

Lee what type of battery is it ? Gel , AGM ( both sealed ) or wet cell acid with caps ?

[BCNZ]

Most storage batteries, be they gel cell, sealed lead acid or wet plate only have a life expectancy of 2 - 4 years.
A battery that has been allowed to drop below the "discharge threshold" may never recover, or if it does, will exhibit symptoms such as poor charge ability, diminished current capability etc.

I just removed two nice big deep cycle batteries out of a motorhome that friends of mine own. They have been sitting for 5 years in a state of discharge, and consequently are stuffed. I have tried slow charging them over a period of a week and they won't come up at all.

There are "smart chargers" on the market which are supposed to be able to "rejuvenate" tired batteries such as these, but I don't know what their success rate is like.
If memory serves me correctly, these chargers "zap" the battery with short duration pulses of high voltage that is supposed to break down the sulphation that occurs between the plates - the reason a battery no longer charges.

I'd be interested to hear reports from anyone who's used one.

The ultimate thing for batteries in motorhomes and such is to fit a solar panel (as mentioned above) to keep the batteries float charged during periods of non-use.
Alternatively, you can do as I did for the aforementioned motorhome and fit a smart charger permanently across the battery and connected to the mains power source. The idea here is to keep the mains connected to the motorhome while it's parked up, thereby keeping the batteries at optimum voltage.

[lee]

Its a "CGB non spillable, rechargable SLA"
its a 12V 70Ah, my other one is the 80Ah

after being on charge for about 24hrs it come up to about 11.5v so far

some interesting reading

[Joey]

Its a "CGB non spillable, rechargable SLA"
its a 12V 70Ah, my other one is the 80Ah

after being on charge for about 24hrs it come up to about 11.5v so far

some interesting reading

A lot of that information refers to wet cell batteries , most of the testing , reconditioning etc does not apply to your battery.
Coming up to 11.5v is a good sign , really you should be using a charger that will charge your battery in 10 hours , this will prevent a lot of the sulphation that kills so many batteries.
In your case you should be using no less than an 8 amp charger , when it is fully charged it will reach 14.4 volts and if ok should drop to around 13.10 if it is still good after about an hour. A good deep cycle battery ( not wet cell ) will only drop by about 0.1v per week with no load , under no circumstances should it ever be allowed to go below 11.0 volts , this is where deep cycle batteries start to go into self destruct mode. While there is a better chance of being able to restore a deep cycle battery allowing it to remain disharged will dramatically shorten it's life , it some cases destroy it completely.

As mentioned by studio1 a smart charger is as important to deep cycle batteries as it is the right choice of battery , normal car battery chargers are not ideal and will often damage gel / agm , VRLA etc because they bring the battery into a de-sulphation state of high charge ( bubbling ) that sealed batteries are not designed for.
The recovery mode that studio1 mentioned is called equalization , where the voltage across the cells is pulsed or held higher than recommended charge voltage to break down sulphation on the cells. , I have rarely seen this have miracle effects on a dead battery , it is designed more to maintain already good batteries.

Despite the old wives tales , there is no battery that benefits from being totally discharged , if you want your battery to last much longer than recommended , size your battery so that is never goes below 50% of it's total capacity and always charge it again as soon as possible.
If you are looking at charts , DoD means depth of discharge and has a dramatic effect on lifespan.

[lee]

thanks joey for the info

Just checked the voltage this morning, 12.4V
however a 1A load (light) dropped it down to 11.5v.

i will just keep it going for a few days, then discharge / charge cycle the battery a few times and see what capacity i still have. If any...........

[BCNZ]

Ok so it is a SLA ..

Definitely a lifespan of 2 - 3 years tops. After that they lose their capacity - even if they have been kept fully charged.

When I was doing alarm systems I would replace any SLA after it had reached 2 years old. Just routine maintenance really.

I did find some batteries that were 4 - 5 years old and still going strong.
It's possible that your battery *may* come up to terminal voltage (13.8 volts) but it may not be able to hold that voltage.

A small load on the battery should not drop the terminal voltage below 11.5 volts when it is fully charged. If it does, then it really is stuffed.

[Uncle Fester]

A drop of 1V with only 1A is a sign that the battery is heavily sulphated or it has dried out.

The latter is more likely if it was over charged and has gassed. Adding demineralised water(NOT ACID) with a syringe might help there, at least worth a try before throwing away.
Zapping combined with a chemical additive called Inox has helped me to desulphate a wet cell battery that was almost unused and always trickle charged with a low power solar cell, until I found out that those batteries do not like trickle charging if they are not periodically discharged and recharged with several amps .
The recylcing took over a month and it has roughly 70% of it's rated capacity back.

Unfortunately I have read too many times that zappers do not work with SLAs. Nor is it likely that this INOX stuff works here.
I have not tried it out though.
The Inox only costs $6 in Supercheap Auto. The company will actually extend the WARRANTY by 12 months if you put it in a brand new battery, so that $6 could be well invested if you end up buying a new (wet acid) battery.

Solid plate wet acid batteries can last longer as stated above.
I have seen them in operation for 10 years. That was however before the European company that made them had outsourced their production to China.

I also had to replace a lot of SLAs that were 2-3 years old when I was doing maintenance work some years back.
The SLA in my UPS has just died too. Probably just over two years old. We have many short very annoying brown outs here.
I am avoiding SLAs like the pest and I use laptops and my note book now.

[BCNZ]

That was however before the European company that made them had outsourced their production to China.

The SLA in my UPS has just died too. Probably just over two years old.

The two go hand in hand.

The plethora of crap that is coming out of china now extends to almost every device and commodity you can think of. If it can be made or copied, china is doing it. This includes SLA batteries.

I had a situation a few years back where I was replacing batteries in a UPS.
I went to my local supplier and noticed they had a range of batteries that seemed to be custom produced, bearing a logo something like "NZ Eco Battery" with a fern on it or some such Kiwi attribute.

Being the patriot that I am, and wanting to support my country, I bought a pair. They were 12 V 17 A/hr units.

I got them home, installed them in the UPS and powered it up. Everything was ok and I left it on the mains for maybe 8 hours to ensure the batteries were fully charged. All the front panel lights indicated everything was ok, so I chucked a load on it and pulled the mains.

The UPS protested and threw up a faulty battery light, then shut down within a few minutes.

Thinking there was a problem with the batteries, I took them back and asked for a replacement set.
These were duly returned home and installed, with the same problem!

I took this set back and talked to the supplier. Their comment?

"Err.... no. If you are using these for an UPS they are not suitable. They are a cheaper offering (read = made in china) and the only battery you should use is the CSB brand."

I forget exactly where CSB are made but I am sure it's not china. Anyway, their batteries work very well in UPS - and a replacement pair of those saw the UPS function perfectly. As it happens, CSB batteries are the only type recommended by APC - a large manufacturer of UPS in the USA.

Herein lies the very reason I will not support china. Their products are by and large rubbish. I wasted a lot of time stuffing around with their junk.

[ebuyaus]

Hi all
this is in response to a deep cycle battery on this thread.
If the battery is fully dischaged and has been like that for a while, it is more than 2 years old chances are it will not recharge and if it does it will not be like it was before. To give you an example. A 35ah deep cycle battery for a golf buggy will have approx 200 cycle discharge recharge if discharge to 90% on the other hand if it is always connected to a charger when not in use a smart charger and if you discharge it through usage to say 50% then you discharge recharge cycle will improve upto 600 cycle or more depending on which battery use. Lets say you using a golf buggy that requires 3.5ah when used. A 35 ah battery when used for 6 hours will discharge to 14ah. Meaning in 6 hours you have used 21ah of a 35ah hour battery. That means this battery has discharged to 60%, if you place it on charge after use and leave it there then you will get almost 600 uses at 6hr which equals to just under 2 years. There is nothing u can do this. If you use the car alternator to charge you deep cycle battery it will never fully charge it and the most you will get is 80% charge from a vehicle alternator as they are not designed to charge deep cycle batteries. A better way to charge your battery is to use a smart charge at home and when on the road you can use the same charger through an inverter. When you are in the outbak you can use a solar panel. If you have any questions please feel free to contact me on itz4u@iprimus.com.au