Battery future w/ grid tie

Thomas

Is it worth the time to try to condition and build AGMs for nightly use, say a volt or two higher than the factory setting? meanially

niel

Re: Battery future w/ grid tie

i'm not too sure what it is you are talking about here, but if you mean to put the charge voltage a volt higher than the factory recommends---don't do it. this is equivalent to putting 25 gallons of gas into the filling tube of a car that holds 12 gallons, but not only are you wasting the electric, you are also destroying the battery in the process. only charge batteries as recommended. it matters not when the battery power is being used as they are only capable of their current capacity rating if not abused or not too old.

Thomas

Re: Battery future w/ grid tie

I am so sure I am not the only one that has heard not just a few stories but downright conflicting information. As I belive I have sifted thru some of it to these conclusions. Batteries are integral, so correct at will...
1. a charging voltage/current ,varies by battery type
1. PV Array state of chargeing % watts today is not the same % watts tomorrow, Voodo, Van Allen,Arlo Guthrie, Magic 'UV and the weather apply.[barometric pressure,dew point and relative humidty/temperature. The precise determinitive relationships aeffecting solar PV performace do escape me though, I dont have the education for it, juct the diction.
2. start/stop points for this voltage/current bulk/absorb/float /load
3.SOC variables, 13 volts today is not 13 volts tomorrow, charge/use history applies
What I want to do is have my batteries at fully charged untill theyre needed by my grid tie at around 4pm
how much can I push that if at all? high end the battery voltage running w invrter load at 15A=about 13.6, which is good to great I think. This is all fine because my batteries wont budge from 12.6-13.6 anyway. Can the nominal operating hence nominal resting voltage be inched up safely? I am waiting for a xantrex c-35 I may need aload controller, the inverter one is low at 11.5 and gobbles everything up that comes down, so I want it off untill a certain voltage, problem is real and usable volts....12.6-13.6 no matter what settings are applied.

niel

Re: Battery future w/ grid tie

volts are volts. period.

it is pointless to try to put more into an agm battery than it is capable of holding and trying to do this can damage the battery. the battery manufacturer should state at what voltage to switch to absorb and what voltage is good for a float charge. they should also give you upon request if there is a maximum current rate (usually by percentage) that one can feed the battery without damaging it too. i think most agms are capable of at least 1/4 c rate. if the battery is fully charged it would switch to a float charge to maintain the battery at full readiness. if you don't charge it all of the way then it's not because the voltage was not set high enough for it just didn't get enough amp hours to bring it to full charge. this could also be because you are draining off much of the charge current to run loads while trying to charge it up. once it is charged it will be ready to power things even many days later without being connected to your solar charging system as agms have a low self discharge rate.

btw, some agm manufacturers list an eq charge for their agms, but i do not recommend it as normal routine maintenance. this is an excess charge as well that would work to bring all cells equally down in capacity and should only be done as a last resort on troublesome agm batteries imho.

again, putting the voltage too high on agm batteries will damage them as this will cause gassing and pop the relief valve. the water lost by doing this will not be able to be replaced and as such capacity will be lost every time it occurs. there is no substitute for doing things right and if you were advised to raise the voltage on an agm battery above manufacturer's recommendations then maybe you should not ever listen to that person again.

Thomas

Re: Battery future w/ grid tie

Thing is though today being the first day of sun in about 5 days and my inverter/battery relationship falling apart about 2 days ago, and at fully charged the batterys wouldn't take the inverter w/out signifigant to 100 % help from the panels. This would lend me to the conclusion that volts are not really volts, some are pencil/pen/marker...this could honestly be explained some other way too. for all I know. O.K. you are right about pushing the reccomendations, even if the preceeding observation lends to continueing voltage...
My agms I believe should be charged @rate of 14.4v with 17 volts. That equals the panels 245 watts.
Float charge maybee set to 13.6 w load for consequenting line voltage of 12.2 to 13.6 this seemed lik a lot to me. I could even set the lvd lower...but that would mean more of these probs I think
look.....my batteries are new generic golf cart, on the aveage numbers I have applied, I got them from thebatterygeek on e-bay, if one average UB sla 35Ahr charge current is reccomended at 12.5 Amps, what is two? I dont know! I have 2.The last thing, the last thing I need is rplacing batteries...

niel

Re: Battery future w/ grid tie

i think you are totally confused and may be trying to take in too much at a time.

it is true there are losses and other factors that necessitate voltages at or higher than 17v from pvs. this is to deliver the needed 14.4v with some reliability. don't worry about the understanding part of it as you certainly are not an electronics technician. without knowing your loads or if they are on during the charging process your battery should normally range with 1.75a for a 5% rate to 10.5a at a 13% rate for charging. for each 35a battery this will generally hold true and it is a good idea to have the discharge rates similarly in that range, but isn't written in stone. also, to preserve battery life you should not drain the batteries beyond 50% so a 35ah battery is good up to 17.5ah. you can draw less to get even better battery life, but going beyond 50% not only shortens the cycle life, but you could damage the battery as well. it is allot to take in and comprehend, but take it slow and eventually it'll start to click.

there is allot of reading you could do with the faqs that our host has assembled on this part of their website,
http://www.windsun.com/
it may help you get some things into a better perspective.

Thomas

Re: Battery future w/ grid tie

the average rate my inverter draws all day is 14a average. my battery bank on the load controller after dark doesnt work all that well, when it has the 'room' to start up is goes right to the pv-inverter level of 14a. the set up use to regulate a little bit, vary in amp load to inverter , lately its been at 14a all the time. Yes I am confused and trying to take in a lot, just a way of sorting, dis sort ating... what is a good voltage to establish 50% as at anyway? my guess is 12.6= 100% right
10.5=0 right?
12.6-10.5=2.1 right
2.1/2=1.05
12.6-1.05 =11.1 as 50%
I have it set to stop working at 12 and start working at 13.6, and float charge at 14, which it rarely gets to w/ the load on, usu. stays around 12.4 w/ load on.
my inverter is my only load, and hopefully will stay that way.
the inverter swings real high-low, hopeing that a xantrex charger will help this some.