Forum Discussion

Muddydogs's avatar
Muddydogs
Explorer
Jul 30, 2015

Is there any hope for these battery's?

I have acquired 6 battery's off RV's that have set for upwards of 4 years connected to the trailers and being bleed dry by the trailers parasitic draws. I was thinking about seeing if I could bring these battery's back to life for trailer use and if nothing else a learning experience in battery charging. I will list the battery's below and what my initial readings where, The battery's are grouped in pairs as they came off the trailers.

Group 1. 2 National 6 volt battery's. Water level low but above plates. One battery showed 1.6 volts the other 2.2 volts.

Group 2. 2 12 volt Interstate group 24 battery's. Water level low but above plates. One battery showed 2 volts the other 2.5 volts.

Group 3. 2 Interstate 6 volt battery's. Water level is below the plates a ways. One battery showed 1 volt the other .5 volts. I sure this group is toast.

I have a Die Hard 60/20/2 amp charger at my disposal. I hooked the charger up to one 6 volt National battery with it set on 60 amps and read a charge reading of 8.5 on the volt meter. The 20 amp setting gave me 6.5 volts. I wasn't sure what the manual or auto mode on the charger got me so I unplugged the charger and went looking for the manual. Once I found the manual there is nothing in it about charge voltage but it does explaining the modes and how to set charge times in the manual mode. It appears that I have a charger capable of delivering a high charge to the battery's for a set time or until the charger decides its charged in auto mode.

So should I even mess with any of these battery's? If so what are your recommendation's to bring them back to life? From what I understand I will need a hydrometer to do this right as well.
  • MEXICOWANDERER's avatar
    MEXICOWANDERER
    Explorer
    Jul 30, 2015
    "What Have You Got To Lose?"







    Without an adjustable carbon pile load tester and good hydrometer this will turn into a great guessing game or is that "gassing game"? Nothing wrong with spending time trying to raise the dead, but with 2.5 volts showing you're going to need a Cardinal, Bishop and Priest as helpers.
  • Muddydogs's avatar
    Muddydogs
    Explorer
    Jul 30, 2015
    I'm not interested in the acid flush as this is a work deal and the safety officer would have a stroke not to mention OSHA regulations. If they are not worth the time I will store them for core charges and replace battery's as needed.
  • Vulcan_Rider's avatar
    Vulcan_Rider
    Explorer
    Jul 30, 2015
    Muddydogs wrote:

    So should I even mess with any of these battery's? If so what are your recommendation's to bring them back to life?


    In my opinion, no.

    There is some element of danger involved with the "acid flush" method but that might be the only way to make them anywhere close to serviceable again.

    Each one should first be charged individually. Doing more than one together can cloud the issue.

    "Regular" deep cycle batteries are really not that expensive.
    I don't think your payback will justify the risk and expenditure of time.
  • westend's avatar
    westend
    Explorer
    Jul 30, 2015
    If left in an uncharged state for four years, those batteries are worth the price of s****. I wouldn't put any effort into it to make them usable. If you haven't s****ped a battery recently, you might be surprised at the price of s**** batteries. Assuming a weight of at least 60 lbs, you may get $12-20 per battery,
  • Peg_Leg's avatar
    Peg_Leg
    Explorer
    Jul 30, 2015
    My uncle used to work in a battery rebuild factory. He said a lot of batteries could be brought back by dumping the electrolyte out and flushing the sentiment from the bottom of the battery using a garden hose. Then putting the electrolyte back in, topping with distilled water and slow charging. His explanation was that flakes in the bottom of the battery would short the plates out.

    We did this for a golf cart battery in FL this past winter. It was still working when I left. I would recommend a plastic container large enough to set the battery into and slowly dumping while wearing rubber gloves and a full face shield. Safety first, if in doubt don't try it.

    Free batteries, some time and water, what have you got to lose. I would charge 2 or 4 of the six volts together to see if they equalize.
  • GordonThree's avatar
    GordonThree
    Explorer
    Jul 30, 2015
    As I understand it, you need the following things:
    1a) An adjustable high current DC POWER SUPPLY rated 20 volts, 5 or more amps
    OR
    1b) a variac transformer and an old school magnetic battery charger (no electronics, no smart/auto mode, just 20 amps continous
    2) A programmable / adjustable signal generator, home made based on a 555 chip or an old benchtop unit from e-bay
    3) A high current DC solid state relay / switch
    4) Several multi meters to monitor voltages and currents
    5) Optionally an oscilloscope to fine-tune the pulses

    Unaided, a battery charger will never deliver a high enough voltage despite however many amps it is rated for. Using a dumb old-school magnetic charger, the variac will let you dial up the input voltage and that will dial up the output voltage into the 16-18 volt range.

    In simple terms, you dial up 16-18 volts and hammer the battery with high current yet short duty cycle bursts of electricty. The idea is to break down (burn up) the crystal bridges that are shorting the plates in the cells. This procedure is called de-sulfating the battery.

    There's a whole lot of noise on the internet about de-sulfating "ruined" batteries, and some folks seem to have success with it.

About Technical Issues

Having RV issues? Connect with others who have been in your shoes.24,193 PostsLatest Activity: Jan 26, 2025