Battery ??'s soc, voltage sg etc

shockman · December 2013

I've had my system working for a while now and not sure I understand the batteries. First off I'm confused with the volt readout on classic, if it reads 11.8v, and I put my meter on bat. posts I generally get about .3 (12.1v) higher. I have temp sender on batts and have also attempted to adjust the Classic to match batts v when installed. What I don't understand is if Classic is giving a temp corrected readout?, and where I should be taking my reading for correct voltage to adjust offset. When I originally set the offset I was getting different readings between battery posts, junction bar, and at the classic end of cables. Now I would expect a small loss of voltage at the charger versus battery post, but I was seeing like .3 to.5 diff. 0n a #6 cable 6ft long?? I'm not sure if temp sending unit needs any set up or if classic automatically knows what to do?? I'm not sure if my voltage settings are correct for float, absorb, eq. etc. if classic and batts aren't on the same page if you now what I mean. My concern is also that I seem to have trouble bringing SG up much higher than 1250 after 3hrs of EQ mode?? Can I correlate SG to actual voltage? How should I set offset on Classic? Does air temp in area of batts equate to batt temp or will they be hotter cause there working?? They are in an area under the house(root celler ish) that sits around 7 to 10 C at this time of year.
If I haven't confused you too much please add direction :>))
Marc

westbranch · December 2013

Re: Battery ??'s soc, voltage sg etc

What are the other numbers on the screen? amps etc...

shockman · December 2013

Re: Battery ??'s soc, voltage sg etc

Not at the cabin so can't answer

Cariboocoot · December 2013

Re: Battery ??'s soc, voltage sg etc

When you take the Voltage reading will also make a difference. During Float current is at its minimum and so V-drop through wiring will be as well. During Bulk current is at its maximum and so will the V-drop.

What you want to get right is the Voltage at the controller and battery when Absorb starts, so that this stage begins at the proper time. You can disconnect the RTS to check this against your Volt meter on the battery, but frankly any measurement is subject to the accuracy of the device doing the measuring. So if neither is accurate you're nowhere. It's all relative anyway.

You should not be bringing SG up with EQ mode; it is for correcting problems. Full-charged SG should be achieved in at least some of the cells by standard charging. If this isn't happening, something is probably wrong with the parameters.

Battery temperature is nearly always warmer than air temperature whether they are charging or discharging because the current flow within them generates heat. The RTS should be as 'internal' to the batteries as possible; not exposed to open air. The standard for the parameters is 25C, and colder will raise the Voltage.

There is no way to correlate SG with Voltage "on the fly", only with at rest Voltage.

I would be concerned about seeing 11.8 Volts even under load.

Are your sig specs correct? You have two parallel strings of 380 Amp hour L16's? That would be 760 Amp hours @ 12 Volts. As such your four 245 Watt panels are a tad low, but I'm really surprised you'd be discharging that much battery so far. It looks like you are using 4.5kW hours per day. At those levels you should probably have a 24 Volt system.

What have you got Absorb Voltage, Time, and End Amps (if any) set at?

shockman · December 2013

Re: Battery ??'s soc, voltage sg etc

I cant tell from memory what the voltage settings are but I don't think time and end amps have been set by me, I think that was left in the Classics hands. You have the set up correct, but I doubt I'm useing anywhere near 4.5kwh. Cabin has only been used on weekends for last couple of months, when not there I have only a small freezer plugged in that is in a unheated area, and the sat. box plugged in and on or I loose programing, and of course inverter inefficiencies. I'm thinking that parameters are not set properly as the batts regularly reach absorb, but seem to drop quite readly to 11.6,7,8V. However when I put volt meter on batts I'm usually .3 higher so have not worried too much about it till lately. I have also seen over 1000watts from panels on the few sunny cold days we've had lately.
I beleive the battery specs claimed 1265 or 1275 as full charge SG, however I seem to have trouble seeing that.
What I have seen with the hydrometer is that all cells seem pretty even.
I'm useing a clamp meter that was recommended on here from Sears.
I may also have trouble getting to Absorb with these cloudy days :>((
Next time out I will try to catch the batts at start of absorb cycle and reset controller offset, should I have RTS disconnected?? and what about loads??
I may also come on here for directions for setting time and end amps unless Classic default mode is properly taking care of that????

Cariboocoot · December 2013

Re: Battery ??'s soc, voltage sg etc

I think the default End Amps is zero, which is probably not what you want, and the default Time is probably 2 hours, again not good for such a large battery bank. Absorb Voltage should be 14.8 for those I think.

If you disconnect the RTS it will cause the Classic to read Voltage "the same way" as your DMM; with no temperature compensation. This is the best for checking how it reads compared to the meter at Absorb level, but be sure to reconnect it for proper functioning.

You may find it advantages to disconnect one string of batteries and charge them separately; it will allow more current to push the battery Voltage up quicker so that there's more time in Absorb. Set the Absorb Time to its maximum and watch the current during the Absorb cycle; you want to see where it plateaus and how long it take to get to that point. That will give you starting numbers for End Amps and maximum Absorb Time.

SolarMusher · December 2013

Re: Battery ??'s soc, voltage sg etc

shockman wrote: »

I've had my system working for a while now and not sure I understand the batteries. First off I'm confused with the volt readout on classic, if it reads 11.8v, and I put my meter on bat. posts I generally get about .3 (12.1v) higher. I have temp sender on batts and have also attempted to adjust the Classic to match batts v when installed. What I don't understand is if Classic is giving a temp corrected readout?, and where I should be taking my reading for correct voltage to adjust offset. When I originally set the offset I was getting different readings between battery posts, junction bar, and at the classic end of cables. Now I would expect a small loss of voltage at the charger versus battery post, but I was seeing like .3 to.5 diff. 0n a #6 cable 6ft long?? I'm not sure if temp sending unit needs any set up or if classic automatically knows what to do?? I'm not sure if my voltage settings are correct for float, absorb, eq. etc. if classic and batts aren't on the same page if you now what I mean. My concern is also that I seem to have trouble bringing SG up much higher than 1250 after 3hrs of EQ mode?? Can I correlate SG to actual voltage? How should I set offset on Classic? Does air temp in area of batts equate to batt temp or will they be hotter cause there working?? They are in an area under the house(root celler ish) that sits around 7 to 10 C at this time of year.
If I haven't confused you too much please add direction :>))
Marc

.2 or .3V offset in bulk is not that much, you should try to check voltage on absorb and I'm pretty sure that your classic will be accurate with a .0 offset. If you choose EA to end absorb and want it to be accurate, I'd suggest you to add a whizbang with shunt from Midnite. It will read real amps to batteries no matter AC or DC loads. You 'll need the last firmware to get it.

shockman · December 2013

Re: Battery ??'s soc, voltage sg etc

Cariboocoot wrote: »

I think the default End Amps is zero, which is probably not what you want, and the default Time is probably 2 hours, again not good for such a large battery bank. Absorb Voltage should be 14.8 for those I think.

If you disconnect the RTS it will cause the Classic to read Voltage "the same way" as your DMM; with no temperature compensation. This is the best for checking how it reads compared to the meter at Absorb level, but be sure to reconnect it for proper functioning.

You may find it advantages to disconnect one string of batteries and charge them separately; it will allow more current to push the battery Voltage up quicker so that there's more time in Absorb. Set the Absorb Time to its maximum and watch the current during the Absorb cycle; you want to see where it plateaus and how long it take to get to that point. That will give you starting numbers for End Amps and maximum Absorb Time.

Okay if I'm out there and can see a sunny day coming I will run genset to charge up close to full before daylight so that I can let the classic take over. May do as u suggest and seperate batts, but I will be back with absorb stats and ?'s on what to set charger time and end amps to. .>)

shockman · December 2013

Re: Battery ??'s soc, voltage sg etc

SolarMusher wrote: »

.2 or .3V offset in bulk is not that much, you should try to check voltage on absorb and I'm pretty sure that your classic will be accurate with a .0 offset. If you choose EA to end absorb and want it to be accurate, I'd suggest you to add a whizbang with shunt from Midnite. It will read real amps to batteries no matter AC or DC loads. You 'll need the last firmware to get it.

I'm struggleing with voltage readings and you want me deal with shunted whizbangs and firmwhats!! hehehe rotflmao!! just kidding, thanks for the tip

shockman · December 2013

Re: Battery ??'s soc, voltage sg etc

okay I'm back!! have just had the better part of today with full sun, now I have questions about what happened!! I spent the last couple of days frustrated at trying to charge up batts, my inverter charger cuts back amperage too soon, like a good little boy, to get me anywhere if I go by SG!! It seems like my voltage is always higher than SG would indicate. Haveing run my big noisy gas hungry gen. to run supposedly my 100A charger for 2 days and still dealing with SG's in the mid 11's I had an epiphany!! why not use my Can. Tire digital charger that will run off my 1000w Honda! Well that worked as well as inverter and consummed 1/10 the fuel. But same problem starts at 35ish amps and before getting to 1150 Sg it cuts back to 20ish, ah a trickel charge again.
So today I watch Can/US game on Honda power and have charger going, low and behold after game sun comes out!! So by 11:30am Classic goes into absorb, showing 15.1V and 14amps going in, DVM show's 15.02 on batt poats, closest I've seen them in agreement, so I unplug temp sender and get 14.8 on Classic. Batt temp according to Classic is 13C, room temp where batts are is 9C. However I'm still only getting 1175 SG?? So after about 3 hours of absorb which holds at 15.1V and 14A, we go to float, which I tried to avoid by changeing ab form 2.5hrs to 4hrs but think I forgot to push enter! Sg after an hour and a half was 1.215, at end of absorb maybe 1.225. So couldn't figure out how to put Classic back into Ab, so I put it into Eq. and got another hour or so of high amps which ended when sun fell below horizon. Now I had SG 1.235. WHY do I always seem to have decent volt readings and low SG??
Is this enough info to set AB time and end amps?? I don't know what I'm looking for for these parameters?

vtmaps · January 2014

Re: Battery ??'s soc, voltage sg etc

shockman wrote: »

Now I had SG 1.235. WHY do I always seem to have decent volt readings and low SG??

SG of 1.235 is progress... you are beginning to get somewhere. You have exactly TWO things you can do: Time and Voltage. You can leave your voltages as they are and increase absorb time or equalization time. Or you can leave the time where it is and increase the voltages. Or you can do both. I recommend that you increase absorb time. Use solar and or generator... whatever it takes. If you can't get the SG up by increasing time, come back to the forum in a few days and we can discuss raising the absorb voltage.

shockman wrote: »

Is this enough info to set AB time and end amps?? I don't know what I'm looking for for these parameters?

No. We're not ready for that yet. Let's see what it takes to get the SG up, and then we can figure out how to keep it up.

--vtMaps

shockman · January 2014

Re: Battery ??'s soc, voltage sg etc

Okay I will increase Ab. time, however this AM I can't see across the lake (1 mile) and forecast shows no sun till Sat.

( so back on gen I go. I will be back out here in a couple of days and hopefully have sun.
Happy New Year to all!
Marc

Battery ??'s soc, voltage sg etc

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