| Author |
Message |
ChuckMC9 (Chucks) (66.167.165.180)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, January 23, 2004 - 9:02 pm: | |
Have read a lot about battery systems & some theory, but I have a simple question that I can't seem to dig out.
I have a temporary 12v deepcycle that I use for a 'work' battery which I charge once a week or so. I monitor voltage to know when I should top off, which I do at never less than 12.3v.
When I get it home and hook up to a 100/15/2A charger in 15A mode it will easily charge in a couple of hours, cutting off at 12.6v, which my charts say is a 100% charge.
Here's where I get cornfused: To give a little more oomph, I then put it in 2A mode where it can stay for 12 hours or more. I usually need to get back to work by then so when I disconnect, it's up to 14+v. (The 2A mode doesn't seem to have a cutoff)
Am I putting more 'juice' into it during the extra 2A cycle, and is that a good thing, or is the 12.6 or so at the end of the 15A cycle where I should stop?
*Is* there a point at which I should stop charging it in 2A mode? Sometimes I am concerned about boiling that you've mentioned.
When we speak of boiling, are we meaning that literally, that the unit gets hot to the touch and boils out the electolyte, or that the fluid is 'bubbling' chemically? I have heard fluid movement bubbling inside there once and got very concerned.
Gawd, hate to sound like such a novice here, so go easy on me.
And I tell you what - I won't tell you how not to prevent a heart attack again if you don't tell me how ammeters work on this thread! ;)
TIA, Guys. |
Richard Bowyer (Drivingmisslazy) (24.196.191.70)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, January 23, 2004 - 11:21 pm: | |
Chuck, in my opinion the full charge voltage on a 12 volt battery is 13.5 - 13.8 volts.
The two amp charger will put a surface charge on the battery a little higher than that. The surface charge can be removed by turning on the headlights for a few minutes, or just letting the battery sit for a few hours. It should drop down from the 14+ volts to the 13.5 volt range after removing the surface charge.
Richard |
Tom Caffrey (Pvcces) (65.74.64.127)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 24, 2004 - 1:51 am: | |
Chuck, the boiling is actually gassing at low temperature. When the battery is fully charged so that there is no more material on the plate to turn into acid is when the voltage ought to peak.
Very little heat will be produced by normal recharging because the absorbed energy is being stored in the battery. Continued charging after reaching full charge will mean that most of the energy will be converted to heat.
When that happens, battery voltage will begin to fall and gas production will increase a lot. That gas is EXPLOSIVE. If you run Hydrocaps on your batteries, most of the gas will turn back into water and fall back into the battery. The caps will get hot.
If you record the amount of power you use before you recharge, both with and without the topoff charge, you will get a pretty good idea how much power you add with the topoff.
If you observe the battery for peak voltage, you will learn when it is fully charged. There are a number of chargers on the market that use this principle to end their charge.
For what it's worth.
Tom Caffrey PD4106-2576
Suncatcher |
BrianMCI96A3 (65.40.154.171)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 24, 2004 - 9:15 am: | |
12.6 seems a little low for a full charge to me too.
I agree with Richard... although I'm sure he'd agree with me that a higher surface charge of 14V or so will not HURT anything, and only needs removing if you need to get a true measurment of the state of charge.
Brian |
BrianMCI96A3 (65.40.154.171)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 24, 2004 - 9:21 am: | |
Tom has the scientific approach nailed(grin)
Brian |
ChuckMC9 (Chucks) (69.3.74.80)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 24, 2004 - 10:44 am: | |
It's at 14.4v right now after being on at the 2A 'mode' all nite. The meter on the charger shows that it's charging at about 1A. There is a rice crispy sound coming from inside, but plenty of fluid. When caps are removed I see slow, light bubbling.
I think you're telling me that this is a normal situation right now. As i am writing this, the voltage slowly moves 14.3-14.4, and I'm guessing that it has peaked and that I should stop. Have never left it longer than this b/c got concerned that I was overjuicing it. I got a chart from homepower.com that shows charging voltage all the way up to 16+ volts, so I guess I'm in safe territory at 14 1/2 or so.
This temporary power solution is a good way to learn! When I get the 'real' system I'll know a lot about battery characteristics.
Thanks all!
-c |
Richard Bowyer (Drivingmisslazy) (24.196.191.70)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 24, 2004 - 11:59 am: | |
If you continue charging at this voltage you will overcharge the battery and it will start gassing.
The battery output voltage is fairly constant and will stay at 14.4 volts generally. Even 1 amp continous will cause damage. Once the current drops to this level you should remove the charger. After several hours, check the battery voltage and see what it is. From the information you provided, I would say that the battery if fully charged.
BTW, Brian and Tom are right on in my opinion.
Richard |
Jack.In.KC (65.26.97.148)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, January 25, 2004 - 1:08 pm: | |
Three stage charging: Below is a reference for the xantrex RV catalog. There is a description of three stage charging on page 16.
http://www.xantrex.com/support/docserve.asp?id=287 |
Stephen Fessenden (Sffess) (65.154.176.113)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, January 25, 2004 - 10:22 pm: | |
New fully charged batteries are 12.65 to 12.7 volts after equilibrating(losing the surface charge). 12.6 is a little low. I would not leave batteries at 14 volts or more except when they are accepting a charge. |
Tony (64.215.196.177)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, January 25, 2004 - 10:33 pm: | |
Hey Guys
13.6 Is what automobiles charge and everyone says that It Is OK. On My bus I was told that the house Batteries charge 15 Volts from the converter and it would be OK
so anything under 14.5 I let It charge and I have never had any problems, the 2-8D's that run the Bus charge 28 volts and I have had the batteries In It for 6 years, so I guess that Is OK also.
Tony |
BrianMCI96A3 (198.81.26.45)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, January 26, 2004 - 11:42 am: | |
Tony, you are confusing battery full charge voltage with alternator charging voltage!
Brian |
Loydd Fones (Tbird) (209.206.172.153)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 11, 2004 - 1:03 pm: | |
Full charge an a batt is 12.7v
If you will wait acouple hours after removing the charger it will read 12.7 to 12.8v after they equalize if it is fully charged.
Tbird |
BrianMCI96A3 (65.40.153.194)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 11, 2004 - 9:12 pm: | |
Loydd, it really all depends on the condition of the battery.
For example: I recently put a pair of 4D batteries on a trickle charger, after I pulled them off the charger the were left to sit for several days, today I measured the voltage in them and both were over just 13 volts... and in the past I've had battries that charged to well over 13 volts after removing the surface charge.
On the flip side, I'd seriously consider replacing a battery that at full charge could only reach 12.5 volts
Brian |
FAST FRED (65.154.177.83)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 12, 2004 - 5:50 am: | |
It takes about 1 V over full to push the energy into a "12V" battery.
So your charger stopping at 12.6 is very low, but was probably done so someone could not overcharge by leaving the unit on for a couple of days/weeks.
The 14V from the trickle charge is better if you want to "fill" up the battery , and dont over do it.
Probably would not overheat the batt , (at 1 or 2A ) but will use some water.
14V is NOT enough to Equalize a deep cycle batt , which needs a controlled charge of 15V or so.
For proper battery recharginmg , there are only two ways to go,
a really $mart 3 or 4 stage charger, V regulator , or inverter charger,
if you want to relax
OR
a dumb charger with a knowledgable operator , and a temp corrected hydrometer.
Do it which ever way you prefer,
FAST FRED |