Ok, I went for the new unblemished ones. I asked for the most recent arrivals and fully charged. They said fully charged is 6.4 and they brought 2 back from the warehouse and loaded them in my pickup. I got home and checked charge with a meter and it read 6.28 on each, the date was G-5 so they must have just gotten them in so you'd think they'd be fully charged. Does 6.28 warrant taking them back and asking them to bring them to 100% (6.4v) or is it close enough not to really matter. Don't want to be petty about it. I had to carry each up 4 floors (elevator's down) to my warehouse space so I'll have to go through that again unless they can charge and keep them till Monday. I should have gone to the warehouse with a meter and not trusted the guy I guess, but that's my nature.
battery purchase question
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SternWake
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dogear52 said:
I would not stress it. My USbattery group 31 12v fully charged rested open circuit voltage was 12.71 or 12.72, and Voltmeters can be off by a few hundredths.
Batteries 'should' leave the factory fully charged, however time is money, and getting that last 2 to 5% in can take hours. and i am sure that 95% is 'good enough' to leave the door for them
New batteries behave strangely until they get a cycle or two, in regards to top charging. My AGMs amps did not taper as quickly as they do after a few cycles. My Northstar AGM refused to hold the 13.0+ voltage until I did a 50% discharge and a 25+ amp recharge.
You do not yet have a charger for your new batteries? Since they are new, when you do get a charging source on them, now it the good time to take specific gravity readings and see how high it reads to establish your baseline.
Tweaking absorption voltage and duration on a solar charge controller is based on how long it takes to get SG back upto baseline.
One need not obsess over this, unless they are trying for maximum service life/cycle life from their batteries.
But there is a significant portion of battery cyclers out there who blindly believe the flashing green lights /full charge indicators of their charging sources without realizing the green light is a liar, and they are compromising battery longevity to some unknown degree by doing so.
If you do not have a plug in charging source for those new USbatteries, you should buy or borrow one.
This following link is a power supply, that has no self protection measures against overloading. It is rated at 30 amps but will do 38 amps( if the battery can accept that much, until it releases the magic smoke.
It is adjustable voltage, so unloaded, you can set it to 13.2v for float voltage and keep those new batteries from self discharging while you await the transition away from the apartment. The voltage on the model i had, and smoked for science, went upto 15.33V maximum.
Adjustable voltage is like adjustable pressure. The lower the battery state of charge, and the higher the set voltage of the power supply, the higher the amp flow. With the following power supply, one must keep the amp flow below 36 amps via the voltage knob, or it will release the magic blue smoke.
http://www.amazon.com/gp/product/B0...d_t=201&pf_rd_p=1944687622&pf_rd_i=B00ENFBXQS
I have a Meanwell RSP-500-15 that does have all the self protections and can do 40 amps at any voltage from 13.12 to 19.23v.
I found my USbattery 12v group 31 required rather obscene durations at high Absorption voltages to truly fully charge, and it behaved abysmally if it did not get the high 14's for several hours each day from the solar.
6v GC batteries are much easier to fully recharge. But for a few, 12v batteries simply cannot compare to 6v GC batteries in a deep cycle application. The 12v batteries in the common sizes for installation into vehicles, despite their sticker saying deep cycle, are not constructed anywhere near as durable as a true deep cycle battery, like a 6v GC battery.
I would not stress the 6.28v, but I would want to get them on a charging source as opposed to letting them sit and self discharge.
Also keep them cooler if you can while you make the transition away from stick and brick. No direct sunlight.
Optimistic Paranoid
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dogear52 said:
Just off the top of my head, given modern manufacturing techniques, I would think that full charge would be 6.4 volts, + or - a small percent. It might be that the manufacturer actually considers, say, anything from 6.35 to 6.45 to be fully charged, with 6.4 being the average. And your meter would also have a + or - tolerance as well, so if you're running into tolerance stacking, the battery might be a hair low (but still "normal") and the meter might be reading a hair low, thus your reading of 6.28.
If you really want to be OCD - and I don't say that critically, I tend to run a little that way myself - get a good hydrometer and double check the specific gravity on all the cells. Fully charged, each cell should be 1.265. The more uniform the readings are on all the cells, the better. The SG will tell the tale better than any voltmeter will.
Also, don't forget that lead acid batteries have a self-discharge rate of about 4% a week, so they started losing some of their charge as soon as they left the factory. That doesn't mean that there is anything wrong with them, that's just normal.
Regards
John
SternWake
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ccbreder said:
A battery warm off the charger will read high from surface charge voltage, and this surface charge voltage can take quite some time to bleed off. Even a non fully charged battery will read high for quite a while after it is removed from a charging source. This tricks many battery depleters into thinking their charging source is more effective than it actually is.
http://www.pbase.com/mainecruising/battery_state_of_charge
The Lifeline AGM I have in my possession took a week to go from 13.23 to 13.13v, and I even had drawn several AH from it for testing, and am not sure what it is going to eventually rest at.
Every battery, even from the same manufacturer, and right next to each other on the manufacturing line, can have a slightly different rested OCV voltage.
The Date code is important. A higher voltage on purchase of an older battery could indicate only that it was recently recharged.
The question is: did they know you were coming, voltmeter in hand?
Or do they decide to add to their electric bill by regularly top charging older batteries that have not yet sold?
Batteries self discharge faster in hotter temperatures, and faster as they age.
My old Flooded USbattery 31 has been taken out of service as a few cells gets way too hot on their bottoms when charging now, and it loses a few % per day just sitting there. It will be down at 12.53v in 5 days, and take 12AH before the automatic Schumacher shuts down, and the PD9245 can feed it 18AH in 4 hours at 14.56v.
