Jim, thanks for the suggestion. So far I have tried the reverse charging on one battery. Here is what my observations are: -initial battery read 4.1V and would not supply current to a load -reversed charged for several seconds but would not draw more than 100mA during this time. -then normal charged where it would only draw a few 100mA. Got up to 7.3V after a few hours and wouldn't supply current to load -reversed charged again and this time it drew around 200 mA - normal charging would now draw 100mA but still wouldn't supply much current to a load. A small lamp lit dimly for 5 minutes and went out. -repeating the reverse charge- normal charge cycles seems to allow more current to be drawn each time. - last I tried, I was able to draw over 1 amp reverse charge and 200 mA normal charge. Battery reads 9.4V after a few hours charge but won't supply much current. I will attempt this on another battery to see if it reacts the same as the first battery. I will also try to reverse charge for a longer time period, such as a full minute. Will post another update on the experiment. Gary McCartney McCartney Electronics Guelph Ontario Canada Est. 1984 email: gary (at) number63.ca Jim Shupe wrote: > Gary... > > Try reverse-charging (limit current to an amp or > less) for a few seconds to a minute to get things > going, then forward-charge at no more than 14.75V > until the current drops below about 100ma. If this > restores some charge to the battery, put it through > several normal charge-discharge cycles to achieve the > best capacity for THIS particular battery(I assign > batteries a "personality", unique to each one's > "experiences"). > If not much happens the first time, repeat several > times before giving up. In my experience, it depends a > lot on the brand and storage conditions(the cooler the > better). > I used to manage storage, maintenance and testing of > gel-cell batteries as a test engineer for a medical > equipment manufacturer, so I experimented with and > researched a lot of this stuff. > > Batteries are still a long way from a reliable > device. BTW...somewhere I have a schematic for a very > good, simple two-stage gel-cell charger if you need > one. > > Jim Shupe, CET > Lloyd's TV > Yucca Valley, CA > > --- Gary McCartney <gary@xxxxxxxxxxx> wrote: > > >>I found a box of 10 brand new sealed lead acid >>batteries, 12V 4AH that I >>forgot I had. Problem is, they are all very low or >>dead. I tried >>connecting my power supply with current limiting but >>the batteries >>aren't drawing any current at all. >> >>Is there any way to kick these into charging up, or >>are they garbage? >>-- >> >> >> >> >>Gary McCartney >> >>McCartney Electronics >>Guelph Ontario Canada >>Est. 1984 >>email: gary (at) number63.ca >> >> >> >> >> >> >> >> > > ----------------------------------------------------------------------------- > >>Lost Password: >>http://www.tech-assist.org and select "Login >>Problems?". >>Email Archives: >>//www.freelists.org/archives/techassist/ >> > > > > ----------------------------------------------------------------------------- > Lost Password: > http://www.tech-assist.org and select "Login Problems?". > Email Archives: > //www.freelists.org/archives/techassist/ > ----------------------------------------------------------------------------- Lost Password: http://www.tech-assist.org and select "Login Problems?". Email Archives: //www.freelists.org/archives/techassist/