Deep-Cycle Battery Questiongreenspun.com : LUSENET : TimeBomb 2000 (Y2000) Preparation Forum : One Thread
I just picked up a couple of small 34AH deep-cycle batteries and after wiring them in parallel I "topped them up" with an automatic charger at the 2-amp setting. When the charger meter indicated charging current had dropped close to zero and I unhooked the charger, I then checked the terminal voltage. I was surprised to find the set tested out at only 11 volts. I had checked each battery before wiring and charging and they read 12 volts. What is going on? These batteries are Everstarts from Walmart and the dating seemed to indicate they were fairly "fresh".
-- Jeremiah Jetson (email@example.com), November 29, 1999
Well, right now they're dead. Even at 12 volts they were pretty discharged. Full charge should be no less than 12.7 volts. Either:
A) You hooked up the charger wrong the first time
or B) The batteries' plates have sulfated somewhat after sitting for a while. Did you buy them new? or were they used? if they were used, they may have been discharged and then left sitting for a season, this will kill a battery.
This was the case with a set of 8- 375AH batteries that I bought last year. They sat for about 8 months and then went I went to charge them, they would not quite hold a full charge.
I had to do what's known as an "Equalization Charge" on the set (which was wired in series). This was charging at a higher voltage (15.5 volts for a 12v array) to kind of force the sulfation off the plates and stir up the electrolyte.
it worked. Batteries now function normal.
Try charging your array again, this time, make sure the connections are correct and if you can't charge at a higher voltage, use a charger with a higher amp rate.
a 2-amp charger is a trickle charger and will only charge up a battery over a long period of time. if these are "deep-cycle" batteries, or even "Marine" deep cycle batteries, you should be able to bulk charge them at 10-20 amps with no problem. This MAY be enough to jolt them back to life.
-- plonk! (firstname.lastname@example.org), November 29, 1999.
I double-checked the instructions and I did hook up the charger properly. I am having someone recharge the batteries at the 10-Amp setting and then will measure the terminal voltage. If it is below 12.7 volts after this, then we will return the batteries for a refund.
-- Jeremiah Jetson (email@example.com), November 29, 1999.