Minimum voltage for charger to detect

[Vandy_Guy]

Just purchased a 2012 EZ GO TXT 48V salvage. Batteries are 2016 and completely dead. I am trying to charge each battery individually with a 6-12V portable charger with the hope of resurrecting them enough for the EZ GO charger to pick them up.

My question is, what is the minimum voltage I need to get across the pack in order for the EZ GO charger to detect them and start charging the 48V pack?

FYI, my first attempt only got the pack up to 24V total which I figured was way too low. The charger blinks red 2x on the problem light. I've also confirmed all batteries have good water level.

Thank you

[scottyb]

Hard to say without know which Ezgo charger you are asking about.

[meimk]

I wouldn't expect a 48 volt charger to come alive till something over 40 volts, some might be as much as 42. Your 24 won't turn on any 36 volt chargers that I know of, unless they are the old manual timer type (doesn't rely on a relay).

[JohnnieB]

If it a 48V Powerwise QE, the battery fault error (2 red flashes) means the battery pack voltage is less than 36V or more than 62.7V

What voltage batteries? 6V, 8V or 12V ?

[Vandy_Guy]

Yes, it's a Powerwise QE. The batteries are 6 x 8V batteries. I'm using a 12V portable charger so I'm being careful with how long I keep each one on the portable. It sounds like if I get the pack over 36V (6+ volts per battery) I might get to a level where the Powerwise can take over. Does that sound right?

Thanks for the help!

[Pepe30269]

Hi Vandy Guy:

I spent over a month trying to get it to work - charging each battery individually to reach the threshold necessary for the GC charger to work. I bought three different chargers and spent lots of time babysitting the process. Nothing. I was talking with a friend who plays an auto mechanic on TV and he thought about it and gave me a suggestion. I tried it and it worked!
Here is the disclaimer. I do not know how safe this is. I do not know if there is potential danger to to damaging anything being used. So make sure you have done your research and talked to others. But, it worked for me...
So here it is. I pulled my 2007 Ram 1500 up close to the distressed golf cart and got out jumper cables. I left the truck running and put red to red, black to black (the same as if one were charging a car battery) to one of the GC batteries.. Then I took my single battery charger and connected it the same way to the same battery. I have 6 x 8v batteries. I charged each battery about 20 minutes but only left the jumper cables on for the first 5 to 7 minutes minutes. After using this method for all six batteries, I checked total voltage and the voltage of each battery to make sure we were good to go. And we were.

Good Luck!

[JohnnieB]

Originally Posted by Vandy_Guy

Yes, it's a Powerwise QE. The batteries are 6 x 8V batteries. I'm using a 12V portable charger so I'm being careful with how long I keep each one on the portable. It sounds like if I get the pack over 36V (6+ volts per battery) I might get to a level where the Powerwise can take over. Does that sound right?

Thanks for the help!

If you are using a 12V charger whose max output is 10A or less and the 8V battery's capacity is 170AH or more, it will take over 17 hours to fully charge them from empty and about 9 hours from half full, so they don't have to be baby-sat all that closely. (Checking on-charge voltage at 1 hr intervals ought to be sufficient.)

The max voltage a 12V charger will put out is up to about 15V, but the voltage it actually puts out while connected to a battery is determined by the battery's on-charge voltage at the time. The on-charge voltage rises as more and more AH are pumped into battery and 10.8V (2.70VPC) is about the max on-charge voltage for an 8V battery. You don't need the batteries fully charged to get the 48V charger to turn on, so I'd only take each them to about an on-charge voltage of about 9V before going to the next one.

[Vandy_Guy]

@Pepe30269 & @JohnnieB - Thanks for the help! Going to give it another go and see where I can get with it.

I did notice something, and it may be due to the fact that I haven't charged them long enough like JohnnieB mentioned, but only 1 of the 6 batteries seems to be holding its charge. The others I've gotten to about 6.5V on the reader and about an hour later they are down to 4-5V. Does this indicate they are toast or should I still give it a shot with more charging time?

Thanks!

[JohnnieB]

If the On-Charge voltage is only about 6.5V, than an At-Rest voltage of about 4.5V sounds about right.

When a lead-acid battery is charged, it acquires a "surface charge" due to the electrolyte closest to the plates having a higher SG than the electrolyte further away. The horizontally stratified electrolyte equiliberates over time once the charger is removed and when the SG is the same throughout the electrolyte, the At-Rest voltage can be measured.

You want at least 6V per battery, so let them charge until the On-Charge voltage is at least 8.5V.

[Vandy_Guy]

@JohnnieB - Thank you!