Surrette S-530 batteries small fraction of capacity

YehoshuaAgapao · February 2013

This is the scenario

Got them in late September

They sat on a palette for about 6 weeks. Voltage was 49.8 when installed and wired.

They were finally installed in early November and they and got maintenance charges from manually running the generator through the inverter every two weeks about.

In late December, the AGS was up and running, after the everything else was installed and passed inspection. Whenever battery voltage dropped below 50.0 the generator starts and charges them back up, about once per week.

Now after another month and a half, SRP is finally coming out to commission on Tuesday and I decided to run the subpanel off-grid today (Sunday) and tomrorrow (Monday). Batteries dropped to 48.5V after 2 hours of variable 0-0.8KW load and another 2 hours under 1.5KW load.

Batteries got their first equalization and watering yesterday (Saturday). They ate up 3 gallons of distilled water. Hungry. Did not see any exposed plates. Watered when they were on float on PV.

Battery temperature sensor is 15 degrees Celsius. This is the first deep cycle these batteries have been through.

You think my batteries my be sulfated? Or need more equalization (charge controllers only equalize for one hour)? Too new and need to be broken-in? Cold (15 degree battery temp) or some combination?

16 Surrete S-530 batteries, 800AH capacity, 38.4KW-h, but look like they are operating at 8KW-h

This is how the batteries are wired:

Charge controllers and inverter go to common DC bus bar in xantrex PDP. The Busbar has two battery lugs for two sets of inverter battery cables. Each string of 8 L16 batteries are in their own Lifetime X-Large deck box and each string has its own inverter battery cables. The batteries are landscape in two rows of 4 in each box. Inverter positive gets in on Batt#1 postive and goes around until Batt#8 negative and goes back to inverter negative.

BB. · February 2013

Re: Surrette S-530 batteries small fraction of capacity

Really a mixed report there...

The batteries should probably have been charged more in storage. But the resting voltage seemed roughly OK.

Your charging time sounds too short for just using the genset at one hour--Not sure it was equalizing or not (I guess you were not using the batteries during that time--Or were you charging with grid power too?).

However, the water usage indicates a fair amount of charging going on--Unless the batteries were not completely filled when shipped.

Battery should be very happy at 15C. I guess you are in the Phoenix Az area--So it can get hot.

Anyway... Probably back to the basics. What are your charging settings (bulk, absorb, equalize, timers, etc.). With this system, you have multiple settings for selling power, AC charging, solar charging, etc... And they can interact. So, what is the sell voltage and other settings.

What amount of charging current are you seeing for your bank? From solar? From AC Grid? From generator?

You have two parallel strings of batteries. Do you have a DC Current Clamp Meter (this one is not expensive and "good enough" for our needs). With a DC Current Clamp meter, you can measure the charging and discharging current for each string and make sure they are each sharing the current/loads/charging.

Do you have a good hydrometer yet? Would like you to log the temperature corrected specific gravity for each cell.

Also, use a volt meter to log the voltage across each cell/battery. With all of these tests, we are looking both for absolute values (how well the batteries are charged), and for differences (cells/batteries not balanced with their mates in the bank).

Usually, our first recommendation is to figure out the state of charge of the battery bank. And then get it fully charged quickly before any damage is done.

The major problems are sulfation (partially discharged batteries setting for days-weeks-months at a time and the lead sulftate crystallizes), running with plates exposed, refilling with tap/well water, and running a bank with two high of charging voltage (over equalization). Poor/bad electrical connections, bad cells (shorted or open) can also be a problem too--and cause other damage if not detected/corrected quickly.

A couple of battery FAQ's to read:

Battery FAQ
www.batteryfaq.org

You don't want your battery bank to set below ~75% state of charge for days/weeks/months. And if it is discharged below 50% SOC, you want to get it back recharged >90% in the next day or so (and hit >90% SOC a couple times a week).

Cycling below 50% SOC often can reduce battery life somewhat. Discharging below 20% SOC can permanently damage one or more cells in your bank.

I like to suggest a Battery Monitor--It makes it easier to see what is going on with your bank--But focusing on Specific Gravity and Cell/Battery voltages is probably key right now.

-Bill

YehoshuaAgapao · February 2013

Re: Surrette S-530 batteries small fraction of capacity

The batteries should probably have been charged more in storage. But the resting voltage seemed roughly OK.

I don't think they ever got below 49.5V.

Your charging time sounds too short for just using the genset at one hour--Not sure it was equalizing or not (I guess you were not using the batteries during that time--Or were you charging with grid power too?).

However, the water usage indicates a fair amount of charging going on--Unless the batteries were not completely filled when shipped.

When manual-generator-charging, I switched everything off, inverter, charge controllers, and all, when done since there was nothing for them to do. It generally charged for 45 minutes to one hour going immediately into absorption. When the AGS was installed and working, I left the inverter on which puts a small draw in the batteries. Charging times increased to 2 hours about with about 20 minutes bulk and the rest absorption. Until yesterday (Saturday), there was no float charging or equalization. The batteries were maintained for 5 months almost exclusively on absorption charge.

Battery should be very happy at 15C. I guess you are in the Phoenix Az area--So it can get hot.

Phoenix is an oven in July

Anyway... Probably back to the basics. What are your charging settings (bulk, absorb, equalize, timers, etc.). With this system, you have multiple settings for selling power, AC charging, solar charging, etc... And they can interact. So, what is the sell voltage and other settings.

Grid tie gets commissioned on Tuesday. Just making sure everything is working and broken-in by then. Plus SRP is not familiar with battery based systems and somebody different is coming out for the commissioning and only their head engineer has any kind of understanding. The inspector initially freaked out with the lack of a PV meter socket (their ICA says no PV meter for battery based systems) and the word 'DC-coupled' (to distinguish from AC-coupled battery banks; Joel, the head engineer told me to take DC coupled out of the drawings because his staff just didn't get the concept and thought I was connecting DC directly into the grid) and simply said everything was wrong until I told him it was a battery based system and he had nothing but clueless ???s. SRP has had issues with AC-coupled battery based systems backfeeding into the grid because the person did not set up their diversion load correctly. I'll be happy that, especially on Saturday when I ran the PV without any grid or loads connected to the inverter (just DC and generator), nothing blew up or malfunctioned with 6.5KW of solar panels operating with only 300W of battery floating work to do because DC-coupled charged controllers can throttle right at the PV source while AC-coupled systems have to deal with a grid-tie inverter that runs on full throttle at all times. Except for this battery under-capacity issue, everything is working great.

What amount of charging current are you seeing for your bank? From solar? From AC Grid? From generator?

Today (Sunday) was a partly cloudy day, but the charge controllers were in float most of the day. After about 4PM, the batteries were in absorption most of the time. The solar array is awesome. At 4:30PM, it was putting out 1800W in the sun, and 400-800W when the clouds covered the sun. At 5:15PM the sunny production dropped to 1200W. Yesterday when I had the PV on but no loads on the inverter, the spent some time in absorption but floated most of the day. I did a single manual equalize yesterday after watering after they reached float. When the generator kicked on at 8:30PM, it was in bulk charge, and the inverter was in bulk charge putting out about 60A (available generator power after subpanel demand). I have eight circuits (four moved, plus 1 moved / split-in-two (chest freezer & family room), plus 2 new dedicated circuits for refrigerator & SHW pumps) on the subpanel, which includes the whole house except kitchen & dining room outlets, dishwasher, microwave, garbage disposal, laundry, and any 220V circuit (A/C, dryer, water heater, pool pump).

You have two parallel strings of batteries. Do you have a DC Current Clamp Meter (this one is not expensive and "good enough" for our needs). With a DC Current Clamp meter, you can measure the charging and discharging current for each string and make sure they are each sharing the current/loads/charging.

I have an Elenco ST-3030. It is a cheap Chinese true-RMS clamp meter similar to the one on your sears link. (paid $55 for it on Amazon.com). Works better on PV wiring than battery wiring but it works on battery wiring on a heavier load. I'll measure it when it is doing a heavy charge on the batteries tomorrow night (might be able to measure in the morning).

Do you have a good hydrometer yet? Would like you to log the temperature corrected specific gravity for each cell.

Not yet. I think hydrometers tell a lot but I figured to voltage would be plenty enough.

Also, use a volt meter to log the voltage across each cell/battery. With all of these tests, we are looking both for absolute values (how well the batteries are charged), and for differences (cells/batteries not balanced with their mates in the bank).

Only time I used a volt meter was the week when the batteries were installed but the inverter was not yet installed. It was 49.5V at the time. Never seen it below 49V until about 8:30PM saturday when the generator kicked on. They were in bulk charge (40-60A) for about two hours and absorption for another hour and a half.

Usually, our first recommendation is to figure out the state of charge of the battery bank. And then get it fully charged quickly before any damage is done.

The major problems are sulfation (partially discharged batteries setting for days-weeks-months at a time and the lead sulfate crystallizes), running with plates exposed, refilling with tap/well water, and running a bank with two high of charging voltage (over equalization). Poor/bad electrical connections, bad cells (shorted or open) can also be a problem too--and cause other damage if not detected/corrected quickly.

A couple of battery FAQ's to read:

Battery FAQ
www.batteryfaq.org

You don't want your battery bank to set below ~75% state of charge for days/weeks/months. And if it is discharged below 50% SOC, you want to get it back recharged >90% in the next day or so (and hit >90% SOC a couple times a week).

Cycling below 50% SOC often can reduce battery life somewhat. Discharging below 20% SOC can permanently damage one or more cells in your bank.

I like to suggest a Battery Monitor--It makes it easier to see what is going on with your bank--But focusing on Specific Gravity and Cell/Battery voltages is probably key right now.

-Bill

Except for maybe the time the batteries sat on the pallet for 6 weeks (I read about some 'surface charge' that can give a falsely high voltage reading), I think they were at least 80% charged at all times. But that could have been false readings because of sulfation from sitting on the pallet for 6 weeks. The first charge on the generator was very short - under 30 minutes. Manual generator charges after that were 45 minutes to 1 hour, all absorption. After the AGS was operational and I started leaving the inverter turned on (in search mode), charge times increased to 2-3 hours every 2 weeks (Have 24hr voltage threshold for AGS set at 50V), with about 30 minutes in bulk and the rest in absorption. The batteries got no PV input until Yesterday (Saturday) and that was the first time they've ever been floated or equalized (Xantrex equalizes for only one hour though). Today was their first deep cycle. Was hoping they would at least until midnight before hitting 48V. Subpanel loads generally ran from 1.3 to 1.5 KW (lowest 0.7KW highest 2KW). I didn't see any exposed plates when watering, but if 3 gallons (about 8 oz per cell to fill them up) is a lot, then they probably were pretty close to getting exposed. I watered with distilled water jugs from Fry's.

Ralph Day · February 2013

Re: Surrette S-530 batteries small fraction of capacity

Please get yourself a hydrometer! Without one it's like trying to guess the amount of gas in your car's tank by looking down the fill spout instead of at the fuel guage (or using a dipstick). A local here has 16 S-530's and the last time I saw them they were almost water (the electrolyte sg). S-530's take a heavy charging regime, especially series parallel banked as yours must be. Plan on lots of charging via grid (cheaper than genset), or genset. With a hydrometer you will know their health and state of charge.

I check sg on every cell in the bank at the beginning of each month, then check water and add at the middle of the month. That breaks the job into 2 lots, about 15 minutes for each rather than at least 30 minutes to check sg and water at the same time. Also the electrolyte level is midway between most concentrated (before watering) and least concentrated (just after watering) at the sg check time. I started out without a hydrometer and probably lost 5 years of the expected life of my Surrette batteries. Go to a auto supply house and buy a cheap unit for $5. They work as accurately as more expensive ones, just make sure the float doesn't stick to the sides of the tube (don't use a plastic pointer type).

Good luck
Ralph

mike95490 · February 2013

Re: Surrette S-530 batteries small fraction of capacity

48.5V / 4 = 12.1v IF all cells shared the load. Attachment not found. So if this was a "resting" voltage measurement, you were definitely in the area where sulfation can occur.

http://www.windsun.com/Batteries/Battery_FAQ.htm#Battery%20Voltages

Vic · February 2013

Re: Surrette S-530 batteries small fraction of capacity

Agree with all: You MUST get and regularly use a good glass Hydrometer!

Also, voltage is a very poor indication of SOC. Voltage readings of batteries that have no charge of load on them are still affected by battery temperature. On 48 V systems, the voltage vs temperature is approximately --0.12 (120 millivolts) per degree C temperature change. So if you were measuring 49.5 V for batteries just resting (no charge and no loads at all), then this could represent a true voltage of about 48.3-ish V. So, this IS in the range of about 50% SOC.

Hope that you have the Surrette Battery Manual. It is important to set all charger and EQ voltages correctly. The EQ voltage should be temperature-compensated, and must be a MINIMUM of 61.9 V. The Hydrometer is an important tool to determine when to EQ, and during EQ, as it will indicate when the EQ needs to be terminated.

In commissioning a new battery bank, you would normally measure and record SG and resting battery voltage -- recording these in your Battery Logbook for future reference. Also the electrolyte levels would be noted and recorded. The comissioning EQ would then be started and monitored.

Three gallons is a lot of water, but if none of the plates were exposed, probably they were shipped a bit short of full.

The Surrette site has some important info regarding charging, and the link to the pdf Manual:
http://support.rollsbattery.com/solution/categories

This should be the Battery Manual link:
http://support.rollsbattery.com/solution/categories/688/folders/10484/articles/654-battery-user-manual-flooded-agm

You may have the Manual, but if you have not done so, read the solutions page links for a good background on your valuable battery maintenance.

Good Luck, and congratulations on the new system. Vic

YehoshuaAgapao · February 2013

Re: Surrette S-530 batteries small fraction of capacity

Agree with all: You MUST get and regularly use a good glass Hydrometer!

Will get one.

Also, voltage is a very poor indication of SOC. Voltage readings of batteries that have no charge of load on them are still affected by battery temperature. On 48 V systems, the voltage vs temperature is approximately --0.12 (120 millivolts) per degree C temperature change. So if you were measuring 49.5 V for batteries just resting (no charge and no loads at all), then this could represent a true voltage of about 48.3-ish V. So, this IS in the range of about 50% SOC.

Hope that you have the Surrette Battery Manual. It is important to set all charger and EQ voltages correctly. The EQ voltage should be temperature-compensated, and must be a MINIMUM of 61.9 V. The Hydrometer is an important tool to determine when to EQ, and during EQ, as it will indicate when the EQ needs to be terminated.

In commissioning a new battery bank, you would normally measure and record SG and resting battery voltage -- recording these in your Battery Logbook for future reference. Also the electrolyte levels would be noted and recorded. The comissioning EQ would then be started and monitored.

These are the settings. Equalize: 64, Bulk: 57.6, Absorption: 57.6, FLoat: 52. All are default flooded settings except float, which is lower because of the table in the manual. I have 2 battery temperature installed, one in each box, though the right box is on the negative terminal and needs to get fixed as it reads 1-1.5C lower than the other one. But the connections were done by Hercules and I can't get it loose.

I'm thinking the batteries need more EQ.

Three gallons is a lot of water, but if none of the plates were exposed, probably they were shipped a bit short of full.

Was running about 8 oz per cell. Was filling a 16oz coup 3x per 2 batteries.

Good Luck, and congratulations on the new system. Vic

Thanks

YehoshuaAgapao · February 2013

Re: Surrette S-530 batteries small fraction of capacity

The grid-tie will be operational on tuesday so I can have it equalize all night if I need to. Didn't want to equalize on generator. I equalized on PV on saturday but it was for just a single 1-hour cycle. The batteries had no other EQ. I'm thinking they need more of that as they were basically just absorption-maintained for 5 months.

Blackcherry04 · February 2013

Re: Surrette S-530 batteries small fraction of capacity

YehoshuaAgapao wrote: »

The grid-tie will be operational on tuesday so I can have it equalize all night if I need to. Didn't want to equalize on generator. I equalized on PV on saturday but it was for just a single 1-hour cycle. The batteries had no other EQ. I'm thinking they need more of that as they were basically just absorption-maintained for 5 months.

Once you get your Hydrometer it'll tell you where you need to go, sounds like you have a good plan already. It looked like your Absorption Voltage might be a little low, the more you can do with the Voltage and Time the less problems you'll have. Also when you do a EQ, just keep on starting it for another hour at a time since It's programed for only one hour. New batteries take from 30-50 cycles to settle in and get easier to predict.

BB. · February 2013

Re: Surrette S-530 batteries small fraction of capacity

Equalization is not really a charging/replacing power used in a battery bank--Instead, it is typically used to "equalize" state of charge levels between series connected cells. If you have 5 cells at 100% State of Charge and one cell at 80% state of charge, then that battery really only has 80% useful capacity.

Equalization is purposely "overcharging" the the "full" cells so that you get enough leakage current through the those cells to recharge the low cells.

In general, cells start at nearly the same charge levels, but can drift over time (month or more). And equalization, by itself (overcharging) is "hard" on battery life (erodes plates, can accelerate positive grid corrosion, etc.)... Normally, you only equalize for an hour or two-three when needed (or every 1-4 months or so, depending on battery brand) for best battery life.

Until you get a hydrometer--You really do not know what is going on with the battery bank.

-Bill

Vic · February 2013

Re: Surrette S-530 batteries small fraction of capacity

Hi Y A,

Believe that your EQ voltage is HIGH -- at the high range of that recommended. Unless the bank is in need of serious EQing, would think that something in the mid 62 V range would be good... like 62.5V but Temp Compendated.

If you can go to the Auto Parts store, as recommended by Ralph, in the next day or so, why not wait (a day or two) before doing the next EQ? This will let you know the SG situation, and the variation of SG between all cells. In the past, Surrette (and other mfgs) recommended EQing, generally, when the SG variation exceeded a certain amount. The last I saw from Surrette was to EQ when the variation was 25 points or more (which is a lot).

Vfloat is a bit low, but for GT, this may not be an issue. Your Vabsorb seems fine as a starting place, although, all of the off grid Surrette banks here are running in the 58.3 - 58.5V range at this time. GT stystem can have somewhat different charging vs Selling strategies in some situations. These considerations may affect the charging voltages a bit. Vic

NorthGuy · February 2013

Re: Surrette S-530 batteries small fraction of capacity

YehoshuaAgapao wrote: »

The grid-tie will be operational on tuesday so I can have it equalize all night if I need to.

Xantrex XW will only equalize for 1 hour. If you need to equalize for longer, you can set the float voltage to 62 (or whatever you fill appropriate for equalization). This way you can keep equalizing for a long time. When your SG stops changing and you need to stop, adjust the float voltage back to 52.

BB. · February 2013

Re: Surrette S-530 batteries small fraction of capacity

Chris has a lot of experience with big Surrettes.

ChrisOlson wrote: »

The saga with our bank goes back to when we bought it. I had the absorb set at 28.8 (we had a 24 volt system then). I could never get the SG's up. So after three months I called Surrette and they gave me an absorb voltage of 31.0, minimum time 2-4 hours. It took a full month of absorbing them at 31.0, plus equalizing every time we had enough power, plus using the generator when we didn't, to finally get the SG's up to 1.255. I've been absorbing at 31.0 (62.0 now on our 48 volt system) and never had a problem since, and that was two years ago.

My experience with Surrette batteries is more the norm than the exception. Everybody that has them has found out they will sulfate and die if you use the same settings as you would for Trojans (or follow their published charging voltage recommendations).

So the first thing I'd do is fully charge them (what you think is fully charged) and check the SG's. If they're low, you got a problem, buddy, and you're in for a long baby sitting session with your batteries to bring them back. You can call Surrette and the first thing they'll tell you to do is a corrective equalization at 16.5 volts.

The thing is, most people fail to read the fine print in Surrette's propaganda and it says right in there that 14.4 for a 12V battery is MINIMUM if long absorb times are available. Well, they got a formula for those long absorb times and it's ridiculous - more hours of sun than you get in a day. The fine print says that if short absorb times are more the norm (real world off-grid) then the absorb voltage has to be increased.
--
Chris

What we would call equalization voltage is really what Chris has seen as needed for Absorb on the Surrettes to get them to a "fully charged" State of Charge.

I would suggest that a "high" absorb voltage gives you some light "fizzing" (or light glug-glug-glug) and equalizing a fully charge cell is like pouring out carbonated soda--very significant bubbling/"boiling".

At this point, undercharging your bank is probably more of a risk vs over charging.

With a hybrid inverter system (like the GT)--Setting th volt volage a bit (closer to 53+ volts) may be a better setting for your bank (the XW Inverter will dump enough current to keep the battery voltage at the "float" voltage).

I know there is an automatic "sell setting" of some sort--Perhaps an XW expert here can go through their suggested setup.

-Bill

YehoshuaAgapao · February 2013

Re: Surrette S-530 batteries small fraction of capacity

Autozone don't sell hydrometers. Neither does Home Depot. NAPA has plastic ones that have red/yellow/green or 25/50/75/100% on them. Probably have to wait to order it online. Anybody know a good brick-and-motar place to get a not-dumbed-down hydrometer so I can use it tonight after work and share the readings?

System has been doing well today. Generator shut down at 3AM last night for low load. The batteries were at absorb-finish and went down to 48.5V by 9AM, which is about 4-5KW-h of drain, which still seems like a very poor battery capacity

These the AGS settings i'm using for normal use:
Voltage On: 24hr: 50V, 2hr: 49V, 30min: 48V, 2min: 47V. No voltage off threshold, turn off at float.
On load: 10A, Off load: 8A
Quiet time: 6:30AM to 6:30PM.

These the AGS settings i'm using for today because it was overcast and raining and solar production was between 250 and 1000 watts:
Voltage On: 24hr: 50V, 2hr: 49V, 30min: 48V, 2min: 47V. No voltage off threshold, turn off at absorb.
On load: 20A, Off load: 16A
Quiet time: 10:30AM to 2:30PM.

No generator runtime today according to my sister. Sun was coming out when I went to lunch.

waynefromnscanada · February 2013

Re: Surrette S-530 batteries small fraction of capacity

YehoshuaAgapao wrote: »

Generator shut down at 3AM last night for low load. The batteries were at absorb-finish and went down to 48.5V by 9AM,.

What was that "absorb-finish" voltage? And how long were the batteries held at that voltage before the generator shut down?
I'm almost certain your batteries are not getting properly charged.

YehoshuaAgapao · February 2013

Re: Surrette S-530 batteries small fraction of capacity

BB. wrote: »

Chris has a lot of experience with big Surrettes.

What we would call equalization voltage is really what Chris has seen as needed for Absorb on the Surrettes to get them to a "fully charged" State of Charge.

I would suggest that a "high" absorb voltage gives you some light "fizzing" (or light glug-glug-glug) and equalizing a fully charge cell is like pouring out carbonated soda--very significant bubbling/"boiling".

At this point, undercharging your bank is probably more of a risk vs over charging.

With a hybrid inverter system (like the GT)--Setting th volt volage a bit (closer to 53+ volts) may be a better setting for your bank (the XW Inverter will dump enough current to keep the battery voltage at the "float" voltage).

I know there is an automatic "sell setting" of some sort--Perhaps an XW expert here can go through their suggested setup.

-Bill

I increased the absorption aggression level to 60V, which was the manual recommended absorption voltage for 0-16 C. 62V (double of Chris's 31V) is in the equalization voltage range.

I observed the behavior. As soon as it got to 57V it climbed rapidly to 60V wihin a period of 15-20 min. It is in absorption now. Amps are dropping at a pretty good rate of speed. I clamp metered the battery cables. Each cable set are within 0.2 amps of each other (absorbing at 48A at the time of measurement).

BB. · February 2013

Re: Surrette S-530 batteries small fraction of capacity

Sounds better.

By the way, I believe some (all?) of the battery voltage readings on the XW are temperature compensated to 20C... I.e., if the battery is at 0C. then -0.005 volt per Degree C.:

(0C - 20C)*(-0.005 per C) * 24 cells = +2.4 volts offset

So, if your XW meter reads 60.0 volts at 0C battery bank, then the actually battery voltage (measured with a DMM) should be 62.4 volts.

I am not sure with the XW--But some charge controllers are known to temperature correct some voltage settings (like absorb and float) and not temperature correct others (like equalize setting).

As always, I like to use an accurate digital volt meter to do "sanity" checks what the battery voltage is vs what is reported by the Charger/Inverter hardware (and their set points).

In theory, when you see the charging current fall to ~1-2% of the battery bank's AH capacity -- I.e., a 200 AH battery bank * 2% = 4 amps -- Then the battery should be full and you can terminate the Absorb charge.

Note that charging current from the charge controller may not be the same amount as the current going into the batter bank (i.e., 10 amps charging current may be 6 amps going to DC loads and 4 amps going to charging battery). A Battery Monitor or current clamp meter on the battery cable will tell you that.

-Bill

YehoshuaAgapao · February 2013

Re: Surrette S-530 batteries small fraction of capacity

By the way, I believe some (all?) of the battery voltage readings on the XW are temperature compensated to 20C... I.e., if the battery is at 0C. then -0.005 volt per Degree C.:

(0C - 20C)*(-0.005 per C) * 24 cells = +2.4 volts offset

So, if your XW meter reads 60.0 volts at 0C battery bank, then the actually battery voltage (measured with a DMM) should be 62.4 volts.

I am not sure with the XW--But some charge controllers are known to temperature correct some voltage settings (like absorb and float) and not temperature correct others (like equalize setting).

As always, I like to use an accurate digital volt meter to do "sanity" checks what the battery voltage is vs what is reported by the Charger/Inverter hardware (and their set points).

These are the voltages from CC1 to CC4 and the inverter: 61.11, 61.2, 61.17, 61.18, 61.45.

Battery temperature readings are 14.8C on the left box (connected to CC1) and 14.9C on the right box (connected to CC2). It is about 5C outside currently, a little warmer in the garge, probably 5C.

Absorption current is currently 13.6A. Battery bank is 800AH (2 strings of 400AH). The batteries have been in absorption for 1.5 hours. The inverter has been cutting out the absorption charge at 8 amps (1%). I increased the max absorb time from 180 min to 240 min since Surrette seems to like longer absorb times but this just makes it absorb to 8A instead of 16A, which is just a few minutes longer.

The inverter is currently charging off of the generator (Kicked on a little after 9PM for low battery voltage - 47.8V after 3.5 hours). Assuming everything goes as planed tomorrow with commissioning, this is my last night of off-grid operation. I do intend to use peak load shave (at 0A, effectively taking the subpanel off-grid during load shave hours) during SRP EZ-3 peak hours (2-5PM) so the batteries will get occasional light cycling during cloudy weather.

Note that charging current from the charge controller may not be the same amount as the current going into the batter bank (i.e., 10 amps charging current may be 6 amps going to DC loads and 4 amps going to charging battery). A Battery Monitor or current clamp meter on the battery cable will tell you that.

When I clamp metered the battery cables, I clamped just right at where the cable goes onto the positive battery terminal. I don't have any DC loads other than charge controller idle usage, 4 server fans on the battery boxes (12V 180 ma Delta AFB1212M, running at 9V because they create aux overload faults @12V on startup because startup current is 270ma, manual allows as low as 7V; 1 each charge controller, 2 each battery box, more for the phoenix oven than hydrogen) and the LEDs of a lightning arrestor.

YehoshuaAgapao · February 2013

Re: Surrette S-530 batteries small fraction of capacity

Absorption current is now at 12A, About 2 hours in absorption.

9.7A, about 3 hours in absorption. The higher absorption voltage is making absorption last a lot longer. The voltage at the inverter is still at 61.45V. Generator is happy and very quiet (because it is running at 30% load and is an inverter-generator). About 1100 watts going into the subpanel and 600 watts to the batteries.

2:30 AM, about 3.5 hours in absorption - fluctuating up and down between 8.7 and 9.0 amps. Can hear occasional sound of a sizable bubble coming up to the surface and popping. BTS temperature at 14.5 (left box) and 14.6C (right box). Still at 61.45 volts.

2:45 AM. fluctuating between 8.5 and 8.8 amps.

Just finished absorption. Voltage once charge is done is 54.7 but is falling quickly. 54.3 and falling. 53.5, still falling decent speed but not as fast. Fans shut down (Have them set to turn on at 56.5V, Off at 54V). Generator is still running. That won't shut down until house load goes down to 8A. It is currently 9A. Battery voltage is at 53.0 now (10 min after charger shut off).

3:15AM: Generator just shut down (house went under 8A for 1 continuous min). Battery voltage was at 52.7V just before then.

I did change max absorption time from 180min to 240min on sunday. Usually it stopped absorption at 15-16A but now it goes to 8A (or lower). Bank size is still set at 800AH. Manual says 2% or time limit. Mine isn't stopping at the 2% anymore. 3AM is about the 4 hour threshold as it went from bulk to absorb at about 11PM (generator started about 9PM so it was in bulk charge for just 2 hours)

BB. · February 2013

Re: Surrette S-530 batteries small fraction of capacity

I was also suggesting measuring the voltage of each cell / volt battery (if you cannot measure the cell voltage). Looking for differences--Ideally each battery (cell) voltage should match every other one in the bank. If you find a "high" or "low" voltage in any of the measurements, you need to look further to see what is happening (i.e., measuring specific gravity, checking cables/connections, etc.).

-Bill

Vic · February 2013

Re: Surrette S-530 batteries small fraction of capacity

BB Bill,

Regarding Chris's situation;

Have stated my personal opinion in the past, that his NEED to do Absorptions at a low EQ voltage is very uncharacteristic of ANY of the off grid Surrette banks that I have seen -- those in use here, and those of others in the area. (these are all Flooded Lead-Antinomy batts)

Chris has mentioned that this was necessary due to the Calcium Grid, which is very unusual as a flooded RE battery construction. This is common for Starting batteries -- Float service with little water consuption (generally, IMHO).

The last paragraph of the quote in BB Bill's post #13 above is essentially a description of an "Opportunity Charge", common for off-gridders during Winter, but at a very high "Absorb" voltage. (62 V is in the low range of recommended EQ V by Surrette).

The reason that I am belaboring this point is that this is very possibly NOT the best advice for the vast majority of RE users of Flooded Surrette batteries. We all need to opportunity charge on occasion, but EQing on each Absorb seems extreame for most Lead Antimony batteries -- the most common Surrette Flooded RE battery.

I do completly agree that overcharging is better than undercharging. AND, that if a bank is not getting charged well, that the Absorption stage duration and voltage is the first/best place to start trying to correct the situation.

Am not trying to grind on anyone, but, as mentioned before, we are using about 58.4 V for Absorb on Surrrette FLA here, with NO indication of stratification. This is the within 0.2 volts common for the other Surrette banks in use by neighbors as well.

Opinions. Off the Soap Box for now. Vic

BB. · February 2013

Re: Surrette S-530 batteries small fraction of capacity

Not a problem Vic--We want the best information possible for the readers... And I have made more than my share of "less than the best" suggestions.

-Bill

YehoshuaAgapao · February 2013

Re: Surrette S-530 batteries small fraction of capacity

Vic wrote: »

BB Bill,

Regarding Chris's situation;

Have stated my personal opinion in the past, that his NEED to do Absorptions at a low EQ voltage is very uncharacteristic of ANY of the off grid Surrette banks that I have seen -- those in use here, and those of others in the area. (these are all Flooded Lead-Antinomy batts)

Chris has mentioned that this was necessary due to the Calcium Grid, which is very unusual as a flooded RE battery construction. This is common for Starting batteries -- Float service with little water consuption (generally, IMHO).

The last paragraph of the quote in BB Bill's post #13 above is essentially a description of an "Opportunity Charge", common for off-gridders during Winter, but at a very high "Absorb" voltage. (62 V is in the low range of recommended EQ V by Surrette).

The reason that I am belaboring this point is that this is very possibly NOT the best advice for the vast majority of RE users of Flooded Surrette batteries. We all need to opportunity charge on occasion, but EQing on each Absorb seems extreame for most Lead Antimony batteries -- the most common Surrette Flooded RE battery.

I do completly agree that overcharging is better than undercharging. AND, that if a bank is not getting charged well, that the Absorption stage duration and voltage is the first/best place to start trying to correct the situation.

Ok I'll put the absorption voltage back to normal until the hydrometer shows up from Amazon next tuesday (Autozone don't have any, NAPA only has dumbed-down, plastic hydrometers, both pushing the tester meters now). I'll leave the timer at 240min (default was 180). The batteries have gone through 2 four-hour absorption charges at this setting, essentially two light-duty extended-duration equalization. Maybe they fixed some of the sulfation, since that is what it looks like what my problem is. I'll also check to see if that undos the Xantrex ignoring the C/50 stop point. I'm thinking I should be at 60-65% of capacity from the batteries being new and the temperature being a little low but it they appear to be running at 25-30%.

Blackcherry04 · February 2013

Re: Surrette S-530 batteries small fraction of capacity

YehoshuaAgapao wrote: »

Ok I'll put the absorption voltage back to normal until the hydrometer shows up from Amazon next tuesday (Autozone don't have any, NAPA only has dumbed-down, plastic hydrometers, both pushing the tester meters now). I'll leave the timer at 240min (default was 180). The batteries have gone through 2 four-hour absorption charges at this setting, essentially two light-duty extended-duration equalization. Maybe they fixed some of the sulfation, since that is what it looks like what my problem is. I'll also check to see if that undos the Xantrex ignoring the C/50 stop point. I'm thinking I should be at 60-65% of capacity from the batteries being new and the temperature being a little low but it they appear to be running at 25-30%.

Once you receive your hydrometer and start using it you'll find whats the right charge regimen for YOUR system. Finding it involves the right amount of Time, Voltage and Current. Using any hard and fast rule is not the best. Something that works for someone that doesn't use their system the way you do is not going to work, to many variables from one system to the next.

YehoshuaAgapao · February 2013

Re: Surrette S-530 batteries small fraction of capacity

The Deka Hydrometer (the traditional straight glass tube and rubber bulb, with thermometer) will arrive on saturday assuming no delays.

Haven't been able to monitor in the afternoons, but both grid-tied mornings have been on absorption charge. There are no significant DC loads running overnight and nothing in the logs suggesting that there was any grid loss. The amperage on the absorption is very low. {system harvest watts}-{subpanel load watts}-{sell watts} is only about 600 (absorbing at 10-12A). There are two charge controllers at 59V about and the other two at 57.5 about and it switches around. I have bulk, absorption, and grid support all set at 57.6V in all 4 charge controllers and the inverter, which should enables 'enhanced interactive mode'.

I have never seen battery voltage go under 50V (I have the recharge volts set to this) in one day before, usually takes at least 1-2 weeks, though during that time, it was just the generator, inverter, and batteries connected to each other (waiting on SRP, running long-term off-grid is expensive, just did it over the weekend to get ready for commissioning and just the thrill of doing it). Maybe the inverter switches to invert mode when the charge controllers wake up but in the early morning the solar doesn't produce enough to feed the subpanel and draws from the batteries. Not sure if the inverter can 'invert' and 'passthrough' at the same time, i'll look it up. If not this could explain the absorption charge. Otherwise my battery health could be getting worse...

NorthGuy · February 2013

Re: Surrette S-530 batteries small fraction of capacity

YehoshuaAgapao wrote: »

There are two charge controllers at 59V about and the other two at 57.5 about and it switches around.

The voltage that XW SCCs display is the voltage that they're measuring. If they're connected to the same batteries, it should be all the same. So should be XW6048. If it's not and SCCs that are producing show higher voltage that the ones that are not producing, that would suggest that there's a voltage drop between SCCs and batteries. (59 - 57.5) is 1.5V. At the low amperages during absorption this is a huge voltage drop. I would check the connections and make sure that the wires between SCCs and batteries are of correct size.

YehoshuaAgapao · February 2013

Re: Surrette S-530 batteries small fraction of capacity

Combiners to the PDP have #2 AWG. Wiring distance from combiner to PDP is about 25 feet. Max wiring distance from panels to combiners is 90' and are run on #6 in flex in the attic. Gets converted #6 because the SCC manual says max #6 (though that is probably both directions in a single conduit) so the positive is spliced from #2 to #6 through the breakers and the negative is spliced blocked in the junction box in the opposite side of the wall (positive comes that way also, without splice). The 57 and 59V jumps around different controllers. It is not constant, but always in pairs, and the pairings are random. The 57 and 59V are battery-side voltage.

Battery cables are 4/0, with separate cable set going to each battery box. Battery voltages between controllers do read very close (within 0.1V) at night and don't jump around every 30-60 sec like in the past two mornings.

There is a significant current difference in each controller - 3 tilted panels (roof+7", never shaded) on #1, 6 tilted panels (roof+7", behind A/C & closer to chimney; standoffs fortunately raised them out of A/C shading for winter

) on #2, 6 flat (Roof-15"; E/W) panels on #3, 12 tilted (15" on near-flat patio roof) panels on #4. #3 is always jumpy on input voltage in the morning because of the shade on one panel by the neighbor's tree.

NorthGuy · February 2013

Re: Surrette S-530 batteries small fraction of capacity

YehoshuaAgapao wrote: »

The 57 and 59V jumps around different controllers. It is not constant, but always in pairs, and the pairings are random. The 57 and 59V are battery-side voltage.

The battery cannot be at 57V and 59V at the same time. It's either 57V or 59V. So, if you see two XCCs displaying different voltage at the same time, something is wrong. If you have a voltmeter, you can measure voltage directly at the battery. You can then compare the measured voltage to the voltage that SCC displays. If they are different then there's some problem with either SCC or the connection between SCC and the battery. So, if you do see a significant difference (such as 1.5 - 2V), it is worth investigating.

This is important because SCCs use the voltage to charge the battery. If SCC has a wrong voltage, it cannot charge the battery correctly.

YehoshuaAgapao · February 2013

Re: Surrette S-530 batteries small fraction of capacity

I woke up early and decided to check on the batteries. Found the inverter doing an absorption charge, at 6A. The bank size is set at 800AH, ReCharge at 50V. I think there is something buggy with the inverter.

I voltmetered all the batteries. The right box is perfect, every battery the same. The left box has first two batteries in the series string are 0.4 volts higher than the other 6. There is white crud growing on the battery terminals in both boxes, mainly on the opposite side of the battery terminal where the nut is. This crud wasn't there last week (batteries got put to true use last saturday).

Blackcherry04 · February 2013

Re: Surrette S-530 batteries small fraction of capacity

Sounds like you have one more day and then you can use your new hydrometer and figure out whats going on. Based on your whole story, it won't be surprising to see some higher than others.

White Crud, I don't know about that. Check your Vent caps, if they are the kind that vent on the side, you can clock them around 180 degrees so the vent holes point away from the terminals. That keeps the corrosion away somewhat. Batteries aren't easy or cheap, use them or lose them.
.

BB. · February 2013

Re: Surrette S-530 batteries small fraction of capacity

You need to clean all the terminals and put anti-corrosive grease/compound on each terminal. There are water miser caps that help filter out the electrolyte mist and keep the battery tops a bit cleaner.

Water Miser Battery Caps

Not having enough ventilation or charging at a bit of high voltage at the end of charge cycle (this is when the batteries generate a lot of hydrogen gas/mist) could make the corrosion problem worse.

-Bill

Surrette S-530 batteries small fraction of capacity

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