Anyone know how to bring back a dead 12v Lead Battery?

[davedave2008]

Anyone know how to bring back a dead 12v Battery? (not volt related)

I have a few dead 12v batts sitting around, wanted to see if i could recharge them.

Any tips/tricks (or special chargers to buy)?

[Henry_FL]

Nope, there scrap ... Battery's sulfate and other age related things. This RE system had its day

[frankydude]

Dead batteries are usually dead because of sulfating on the lead plates.
You need to de-sulfate them and for this purpose, there is some commercially available desulfators.
What these devices do is essentially to is to emit to the battery a high voltage pulse of very short duration,
at regular intervals. Those pulses breakup the sulfate crystals that did form over the lead plates, effectively cleaning up
those plates. However, depending on the sulfatation level, the acid concentration might not become correct after
desulfatation completes. You still might need to replace the sulfuric acid solution, and that need to be done with very high
precautions, as acid can cause severe burns. Also, start the desulfatation process by adding distilled water to the top level
indicator of the cells.

Anyhow, without a desulfator, those batteries are effectively dead.

HTH,

Francois
B-2653

PS check with keywork "desulfator" on Ebay, you might find something that suits your application.

[solar_dave]

IMHO desulphators are just scams, the sulphate becomes extremely hard and even if it comes off the plates it traps the sulphur needed to be in the acid. Most likely those batteries are toast. What voltage do the show?

[Einar]

Hmmm . . . desulphators do work, but you need a good one (there are quite a few "wannabes" out there that don't have their charge and desulphation algorithms set properly and do little or nothing for a battery). When looking into chargers/desulphators for my deep cycle and car batteries I found the Batteryminder #12248 getting excellent reviews from the majority of people (and most of those with criticism revealed the depths of their ignorance in their complaints so I discounted them - kinda like we do those people who criticise the Volt without ever having driven one). I bought one - not cheap at a bit over $90, but I have found it to be a very worthwhile investment. It can't and won't bring back every battery but it will test the battery first and let you know if it's totally gone or if it can fix it. Be aware, with charging rates of 2, 4, or 8 amps it 1) can't crank over your car by itself, and 2) it can take a while to charge a largish battery, and even longer when it enters maintenance (desulphation/reconditioning) mode after the initial charge is complete. On the other hand, it is safe to leave hooked up to your battery for extended periods and will not boil the battery dry over the course of a season or two. It has saved me several times the purchase price by bringing back batteries I was sure were only worth the core charge (ie. deader than a doornail) and extending the service life of some deep cycles I use (and abuse) on a routine basis to over eight years and still going. Look into one - I would certainly recommend it. Batteryminder #12248 - charges 12 volt flooded, AGM, and gel cel batteries at 2, 4, or 8 amps (type and rate user selectable) and incorporates desulphation/recovery protocols into its maintenance/float mode.

[davewilks]

Anyone know how to bring back a dead 12v Battery? (not volt related)
I have a few dead 12v batts sitting around, wanted to see if i could recharge them.
Any tips/tricks (or special chargers to buy)?

The batteries in the photograph look like 6 volt Trojans to me.

[Raymondjram]

In addition to a complete discharged cell, these lead-acid batteries can suffer two other problems:

1) Open cells - the cell circuit can open if one or more electrode plates has eroded enough to disconnect from the cell connector. The entire cell is useless, and only a full reconstruction with new plates is the solution (essentially a new battery). When attempting to charge, the voltage across the cell is the highest, and the charge current is zero.

2) Shorted cells - the electrode plate material has eroded (or precipitated) and fallen to the bottom of the cell, causing a physical and electrical short circuit between the electrodes. When charging, the voltage across is very low, and the current is high, causing some heating. This cell can be revived partially by replacing the acid-water with new acid water, or flushing out the cell to remove the loose material. If the cell is weaken by the loss of material to the bottom, the flush can destroy what is left and open the cell.

Both problems are eventually the major reasons to completely replace the battery. Automobile batteries are enclosed in a way to prevent layperson repairs, but large battery banks (as used in UPS systems) use individual and transparent cells that are easy to diagnose for these two problems, easy to replace (once cell at a time), and each cell is repairable (replace electrode plates).

As most of the recommendations posted here are to replace the batteries, please be careful because of the weight and acid in each battery.

[SolarVolt]

The batteries in the photograph look like 6 volt Trojans to me.

Agreed, maybe T-105's.

When I bought mine from Trojan, they were sold with a 7 year warranty for solar use... As long as the batteries were being charged properly.

[hamchief]

Interesting how so many posters on the Volt site have knowlege of renewable energy systems!

I think we'd all agree that whatever you do, the batteries will never have their "like-new" capacity.
Lead is the most recycled non-precious metal - any junkyard will give you at least $5 each (I know, not a large % of the purchase price).

You can try desulphating them which may increase their diminished capacity.

Probably, the cheapest thing you can do is this:
Top off the batteries with distilled water
Leave the caps off and overcharge them - let them bubble real good OUTSIDE, AWAY FROM FLAMES!!!!
Change out the electrolyte - CAREFULLY
It'd be easier to try it out on one battery first.

Actually, it'd be easiest (and most effective and safest) to just take the $5 each and replace them (all of them - to keep the series string balanced).

[DarkStar]

Anyone know how to bring back a dead 12v Battery? (not volt related)

I have a few dead 12v batts sitting around, wanted to see if i could recharge them.

Any tips/tricks (or special chargers to buy)?

First step is to make sure the rest of your RE system is functioning properly, we can replace the batteries or charge them up, but if the system can't maintain them it won't do any good.

Measure the voltage of each battery. As it was previously stated, these are 6 volt Trojan batteries. If your voltage per battery is 5.25 volts or higher (1.75 volts per cell), you should be able to recover them, below that and you'll probably have to scrap them.

If the voltage is good, here's what I would do. Get a good, high quality battery charger like a Schumacher SC-600A SpeedCharge (Amazon.com link).

Take two of the batteries and connect them in series so you have a "normal" 12 volt cell equivalent, open the vent caps and put in just enough distilled water to make sure just the plates are covered. Don't fill to the normal level yet. Leave the caps on loose on the tops.

Go ahead and charge these on the 6 amp, medium charge setting on the SC-600A and let it charge them up. It should take a while for them to come up to full charging voltage, luckily with this charger it will automatically power off once the battery is fully charged. I'm not sure what the amp-hour rating on those batteries, but basically you'll take that and divide by 6 to get the number of hours it will take (minimum).

Once the batteries are charged, check the voltage after the batteries have been off the charger for a few hours. Hopefully they're back up to about 6.36 volts per battery. If it's 6 volts or lower, the capacity is below 50% and should be replaced.

If the voltage is good, top off the batteries with distilled water, cap them and throw them back in the system!

I highly recommend checking out the Deep Cycle Battery FAQ for more information on RE system batteries and visit the Wind-Sun RE Forums with any questions.