I know this is a dead battery question but there is more...
I have a remote off grid site with a 3 Kw array a single classic 150, Schnieder SW4048 and a couple DC-DC converters (48-12 and 48-24 volt) . This is a communications site that I have the ability to remotely monitor TNX to CCDM on a pi.
Back on December 26th 2021 after 10 days of no real solar production the site went off line. Today I was finally able to get to the site, I had to wait for the snow to melt. The battery bank 8 Rolls S6 L16-HC is sitting at 15 volts, the Classic 150 wasn't even powered on, the array showed 80VDC open circuit (it was pouring rain as well the site was in the clouds).
I didn't have a ton of time to try and figure everything out. I connected the solar array directly to the batteries thinking it might trick the Classic to come on, but that didn't work. all the radios came on while doing this and everyone though things were working, for a brief minute anyway.
I ended up pulling the Classic to bring it home and test it.
What is the chance the batteries can be revived? The batteries are less than 2 years old. up until the site went offline they mostly saw less than 10% DOD, occasionally 30-40% DOD a couple times a year. They were always watered during site visits, during the time they were in service I used less that 4 gallons of water for all 8 batteries. the site does see negative temps the morning the site went off line the BTS remoted a temp of 30f. they do site inside an insulted box, but the building in CMU type construction on top of a mountain! I check the SG in early December 2021 all cells varied between 1.25-1.265 the entire bank was 100% charged the battery temp was 55f at the time of testing
If the battery voltage dropped too low would this cause the Classic to power off and not come on even thought the solar array was making power? hence why it never charged the batteries?
Also I discovered that the SW4048 (which was turned off in December for the winter, no AC loads) cycled on when I applied array power to the batteries. has any one ever had this issue before?
I had thought I had a little more "fudge" factor this past winter. The previous winter (no outages) The average daily draw was around 1.2kWh. Last fall I added two PTP MW radios, this ran things up to 2.5 kWh. This year we are planning on adding two more PTP MW links which is expected to take our daily use age to 5kWh. I have already purchased another set (8) Rolls S6 L16-HC batteries, I was planning on using them as a second string with the current batteries. However in light of the current batteries condition I may be forced to buy and additional 8 L16-HC.
Already have a 10Kw Propane Generac to provide power the SW4048 and charge the batteries, ComBox and AGS as well.
Considering if it would be possible to revive the original L16's and use them as a 12VDC bank for the radio equipment.
I am curious to hear everyone's input, let me have it!
TNX Jim
Maybe time to switch over to lithiums that have heaters in them.
Some are designed to shut down if too cold but will warm back up using PV only first before charging again.
Too bad all that stuff shut down on you, but then the inverter came back on and messed things up worse ?
Was the no solar production due to snow covered PV or is that when the Classic failed ?
I guess you will just have to try and charge your batteries and then load test them to see what they will do now or if they got too sulfated up over time.
Larry
Possible lightning damage to electronics? Vic
Hi, jim, and the group,
Lead acid batteries can take one hell of a beating and still bounce back.
Assuming the electrolyte didn't freeze, fire up the generator and set the charger (The 4048 inverter/charger) to equalization and put the beans to the batteries. This may take several days. You didn't say how long they have been sitting at that low voltage? Days or weeks?
You didn't mention what the individual battery voltages were. There is a possibility that only one battery has failed, and pulled the entire string down
With that much radio equipment in the shed, I wonder why none of the low voltage disconnects didn't come on? As you might already know, the Classic had dry contacts that could be configured to close under low battery conditions. Easily interfaced into the radio system to give a heads up that something is amuck at the site.
Provided the batteries didn't set too long at such a low voltage, It's highly possible they'll bounce back after a few charge/discharge/equalization cycles.
And like Vic mentioned, a lighting strike seems quite possible considering all the backup systems failed.
Did you have a chance to test the Classic?
Besure to keep us posted
mike
I wish I could go the Lithium but for now that is price prohibitive. And those would have to be some really good heaters. Temps can be sub zero at times and easily sub freezing inside the building for days if not weeks!!
The last recorded voltage on 12/26/21 was 46 volts since then they dropped to 15 volts. I didn’t have time to check the SG.
Unfortunately I was dumb and didn’t have a LVDC on anything
What I did find kind of weird is the Pi last reported 46 volts. Then everything shut of. Despite the DC-DC converters have an input voltage range of 36-72 volts.
I don’t think there was any lighting. I have only observed lighting in a snow storm once. It is very rare
The site had received several feet of snow. The panels are fixed at 60 degree tilt and they are on a built g at the ridge line at 7300. So snow really doesn’t build up it blows off.
I will be interested to see what the SG of all the cells are.
I plan on taking up a generator and running that into the inverter to let it charge.
As for the Classic I hooked it up to a battery bank (12 VDC) it powered right up. Need to hook up a panel an see what happens
Any other thoughts?
Jim.
Quote from: MountianComm on June 08, 2022, 12:31:17 AM
I wish I could go the Lithium but for now that is price prohibitive. And those would have to be some really good heaters. Temps can be sub zero at times and easily sub freezing inside the building for days if not weeks!!
The last recorded voltage on 12/26/21 was 46 volts since then they dropped to 15 volts. I didn’t have time to check the SG.
Unfortunately I was dumb and didn’t have a LVDC on anything
What I did find kind of weird is the Pi last reported 46 volts. Then everything shut of. Despite the DC-DC converters have an input voltage range of 36-72 volts.
I don’t think there was any lighting. I have only observed lighting in a snow storm once. It is very rare
The site had received several feet of snow. The panels are fixed at 60 degree tilt and they are on a built g at the ridge line at 7300. So snow really doesn’t build up it blows off.
I will be interested to see what the SG of all the cells are.
I plan on taking up a generator and running that into the inverter to let it charge.
As for the Classic I hooked it up to a battery bank (12 VDC) it powered right up. Need to hook up a panel an see what happens
Any other thoughts?
Jim.
Hi, Jim,
It's an old cliché but it serves this example perfectly. "No sense locking the gate after the horse gets out." But seriously, you need to install a Low Voltage Disconnect. I'm not sure, but I think the classic can do that with the AUX contacts. It might be a matter of simply selecting the required menu. Of course the contacts inside the Classic won't handle the current, so an smaller control relay will be needed. I'm sure you can figure it out. Personally, I'd use a mercury displacement relay that is normally open. Those relays can handle huge currents, won't arc and spark when they open and close, either.
Apparently you can monitor the site remotely, and while I'm not a code guy, I'd grab a 13 year old and ask him/her to add a few lines of code to report a low battery condition. Sounds like you have a repeater on the side of the mountain. Ham radio? If you do, it would be easy to slip in a "L" at about 3khz of deviation to let the users know something is wrong with the power source. That's assuming your repeater controller is fancy enough to allow that.
It's so damn easy for me to come up with solutions to your problem while I sit in front of my computer. I don't have a clue what you got going in that repeater shed.
Once you get back up the mountain, take voltage tests of the batteries. Then SP of the cells. Look for bugled sides (from freezing) Frozen cells might not come back.
Run the trace inverter/charger full beans into the batteries. Monitor their temperature. Add water as needed. Hammer them hard. They'll get a bit feisty but they'll take it. The idea (plan) is the break off the sulfation on the plates. Depending on how long they have set discharged will determine if they can be recovered.
I haven't drank the Lithium Koolaid yet. Yes, they have advantages over lead acid. A well maintained lead acid battery bank will provide year after year of service. They do require much more maintenance than lithium.
Get a good refractometer and lean how to use it. Keep records of SG along with dates for each cell.
The number one reason Lead Acid batteries are murdered is by not getting them charged 100% as quickly as you can.
Wayback in the 80's when solar panels were so damn expensive, nearly everyone off grid was under sized when it came for PV. The result? The batteries sat 90% of the time at 50% or so state of charge. The batteries would soon sulfate, and without the ability to ramp up the voltage high enough, the batteries would fail at an alarming rate. If you got 2 years off of a set of golf cart batteries back then, you were the minority. A battery God!
You mentioned that the last voltage reading of 46V came on 12/26/21. Have the sat discharge for 6 months now?
Mike
Mike, short answer is yes, they have sat discharged for 6 months. They have discharged from 46 volts at the end of December to 15 volts now. I did not see any bulging on any of the cells when I inspected them.
About a 2weeks before this happened there was a pretty good storm lasted 5 days. The batteries dropped down to 50%SOC it took about 12 hours of good sun before they were back to 100%. roughly two days of charging. The batteries stayed above freezing (35-45F degrees during this storm) however the storm that did take them out the last temp I saw was 30F.
Headed to the site the end of next week. Plan is to run the Generator in to the inverter and see how well things charge up!
I dropped of the LVDC last trip. plan is to hook it up next trip. Going to reconfigure everything to accommodate a second Array (1.3 Kw) / 2nd Classic 150. Also considering a wind turbine!
TNX Jim
Quote from: MountianComm on June 18, 2022, 02:43:26 AM
Mike, short answer is yes, they have sat discharged for 6 months. They have discharged from 46 volts at the end of December to 15 volts now. I did not see any bulging on any of the cells when I inspected them.
About a 2weeks before this happened there was a pretty good storm lasted 5 days. The batteries dropped down to 50%SOC it took about 12 hours of good sun before they were back to 100%. roughly two days of charging. The batteries stayed above freezing (35-45F degrees during this storm) however the storm that did take them out the last temp I saw was 30F.
Headed to the site the end of next week. Plan is to run the Generator in to the inverter and see how well things charge up!
I dropped of the LVDC last trip. plan is to hook it up next trip. Going to reconfigure everything to accommodate a second Array (1.3 Kw) / 2nd Classic 150. Also considering a wind turbine!
TNX Jim
Ouch!
Six months at extra low voltage sounds deadly to me. The Rolls batteries are brutes, and they may make a comeback. Fingers crossed!
Have you figured out what went fubar?
mike
I would say to top off the water level and do a higher than normal voltage Absorb or EQ for a while while watching the system of course.
Don't want to boil it dry but you might be able to de-sulfate the plates some.
Otherwise, you might want to get a hold of Steve Higgens at Rolls and see if he has some good ideas.
BTW, WHERE are people finding distilled water these days ? All of the stores I go to do not have any at all lately.
boB
Quote from: boB on June 18, 2022, 07:15:36 PM
... BTW, WHERE are people finding distilled water these days ? All of the stores I go to do not have any at all lately.
boB
Hi boB,
YES, since January of '21 Distilled Water supplies have been very, very spotty. It is a bit curious, that we went about 2 years of CoVID drama, without many supply issues ... then, this.
We customarily, in the past four, or so years we have bought distilled water at Wallmart, but from January '22, until now, there is NO STOCK there, or at supermarkets, more than half of the times that we are out looking for it.
My assumption, is that this is a low-margin item, which is heavy, and therefore it has low priority in getting space on scarce trucks.
You might also check hardware stores, like Ace, which would often have stock in gallons at about $2.60 ea, A bit higher cost, which was probably why they had any in stock.
73 GL, Vic
I hear that Winco may also have DW.
Will check later.
boB
Beware of "distilled" or DI water. I've lost my NiFe bank to a batch of water last December, store brand distilled ( Safeway grocery stores) I had a water tester which I used on "water store" water, till they could not keep filters cleaned and I started getting 5PPM water from them. So I switched to grocery store water, at 3x the cost, and bought a couple gallons each trip, then every 6mo, refill the batteries. Fine for 2 years. But then December came, filled the batteries and the bank was toast in 2 days, wouldn't hold a charge. Ran off generator for about a month, trying to figure out what happened, and
then finally tested the 'distilled water'. over 100ppm of mineral content. Safeway said bring the receipts and they would pay me back for the water.
Get a $15 TDS tester from amazon and test each jug of water before using it. (store bought or not)
Quote from: mike90045 on June 19, 2022, 06:18:28 PM
Beware of "distilled" or DI water. I've lost my NiFe bank to a batch of water last December, store brand distilled ( Safeway grocery stores) I had a water tester which I used on "water store" water, till they could not keep filters cleaned and I started getting 5PPM water from them. So I switched to grocery store water, at 3x the cost, and bought a couple gallons each trip, then every 6mo, refill the batteries. Fine for 2 years. But then December came, filled the batteries and the bank was toast in 2 days, wouldn't hold a charge. Ran off generator for about a month, trying to figure out what happened, and
then finally tested the 'distilled water'. over 100ppm of mineral content. Safeway said bring the receipts and they would pay me back for the water.
Get a $15 TDS tester from amazon and test each jug of water before using it. (store bought or not)
WoW !! What an experience ! I will definitely get one of thsoe TDS testers !
Thanks for the info
Quote from: mike90045 on June 19, 2022, 06:18:28 PM
Beware of "distilled" or DI water. I've lost my NiFe bank to a batch of water last December, store brand distilled ( Safeway grocery stores) I had a water tester which I used on "water store" water, till they could not keep filters cleaned and I started getting 5PPM water from them. So I switched to grocery store water, at 3x the cost, and bought a couple gallons each trip, then every 6mo, refill the batteries. Fine for 2 years. But then December came, filled the batteries and the bank was toast in 2 days, wouldn't hold a charge. Ran off generator for about a month, trying to figure out what happened, and
then finally tested the 'distilled water'. over 100ppm of mineral content. Safeway said bring the receipts and they would pay me back for the water.
Get a $15 TDS tester from amazon and test each jug of water before using it. (store bought or not)
This was eye opening to me when I saw a new bottle of distilled water tested and it was high in content. Anyone with flooded batteries needs TDS tester for sure
I went back to the site and took up new batteries. Pulled the old ones and brought them home. I didn’t have time to test the SG (left my hydrometer at the site). But individual battery voltage is 2.75 volts. I plan on testing the SG this weekend when I get home.
When the batteries went out I know it/they were at or below freezing and temps continued to drop. None of the cells are cracked or bulged. I did have temp comp enabled but I also noticed there is a minimum voltage setting for this! Mine was at 48 volts. Not sure if this was an issue. Also I had set my bulk absorbed to 58 volts. It should have ben 60 volts for the batteries. I didn’t have equalization enabled too. I had concerns about the DC-DC converts for the radios one of them has a voltage input of 44-58 volts. When I installed the new batteries yesterday I set the bulk/absorption voltage to 60 volts. Radios stayed on so the converter must be ok.
Any suggestions on settings here? I don’t have equalization enabled. I am a little concerned about excess water use. There are about 5-6 months I can’t drive to the site. Never had exposed plates on the set that failed.
If I can revive this set of batteries I am thinking about using them as a 12 volt bank for radios/repeaters. I was thinking about getting a KID to charge them with. But instead of solar input I would connect this to the 48volt new battery bank. I want something that will handle all the charging. I would imagine that if I did this the KID would be in float 99% of the time.
Jim.
Quote from: MountianComm on June 21, 2022, 03:16:33 AM
I went back to the site and took up new batteries. Pulled the old ones and brought them home. I didn’t have time to test the SG (left my hydrometer at the site). But individual battery voltage is 2.75 volts. I plan on testing the SG this weekend when I get home.
When the batteries went out I know it/they were at or below freezing and temps continued to drop. None of the cells are cracked or bulged. I did have temp comp enabled but I also noticed there is a minimum voltage setting for this! Mine was at 48 volts. Not sure if this was an issue. Also I had set my bulk absorbed to 58 volts. It should have ben 60 volts for the batteries. I didn’t have equalization enabled too. I had concerns about the DC-DC converts for the radios one of them has a voltage input of 44-58 volts. When I installed the new batteries yesterday I set the bulk/absorption voltage to 60 volts. Radios stayed on so the converter must be ok.
Any suggestions on settings here? I don’t have equalization enabled. I am a little concerned about excess water use. There are about 5-6 months I can’t drive to the site. Never had exposed plates on the set that failed.
If I can revive this set of batteries I am thinking about using them as a 12 volt bank for radios/repeaters. I was thinking about getting a KID to charge them with. But instead of solar input I would connect this to the 48volt new battery bank. I want something that will handle all the charging. I would imagine that if I did this the KID would be in float 99% of the time.
Jim.
Jim,
Lead-Acid batteries live in their own little world. Each brand/manufactuer has slightly different needs when it comes to voltages used for absorption, float, and equalization.
So to shuck it down to the cob, 60V is a tad high for absorptionâ€"you'll go though a lot of water. The equalization voltage I use here is 60.2V. My batteries go into absorb at 58.9V and the Classic holds that voltage for two hours.
I float my 16 US BATTERY L-16HC nominal 48V at 54.2V
I never did like automatic equalization. The stars never align correctly! When the time comes to auto equalize, it's raining. Or, the batteries are low and can't reach the equalization set point. You do need to equalize this battery at least once per month. Equalization keeps the sulfate from building up on the plates, and of course balances the voltages between cells.
An automatic watering system would take care of the batteries' need however I'd be worried that the whole shebang would freeze during the winter.
Have you determined the cause of failure? At the price of batteries, I'd like to know what happened to kill off several thousand dollars worth of batteries before I replaced them.
Mike
Quote from: MountianComm on June 21, 2022, 03:16:33 AM
I went back to the site and took up new batteries. Pulled the old ones and brought them home. I didn’t have time to test the SG (left my hydrometer at the site). But individual battery voltage is 2.75 volts. I plan on testing the SG this weekend when I get home.
When the batteries went out I know it/they were at or below freezing and temps continued to drop. None of the cells are cracked or bulged. I did have temp comp enabled but I also noticed there is a minimum voltage setting for this! Mine was at 48 volts. Not sure if this was an issue. Also I had set my bulk absorbed to 58 volts. It should have ben 60 volts for the batteries. I didn’t have equalization enabled too. I had concerns about the DC-DC converts for the radios one of them has a voltage input of 44-58 volts. When I installed the new batteries yesterday I set the bulk/absorption voltage to 60 volts. Radios stayed on so the converter must be ok.
Any suggestions on settings here? I don’t have equalization enabled. I am a little concerned about excess water use. There are about 5-6 months I can’t drive to the site. Never had exposed plates on the set that failed.
If I can revive this set of batteries I am thinking about using them as a 12 volt bank for radios/repeaters. I was thinking about getting a KID to charge them with. But instead of solar input I would connect this to the 48volt new battery bank. I want something that will handle all the charging. I would imagine that if I did this the KID would be in float 99% of the time.
Jim.
The Classic has a Minimum and Maximum voltage setting.
Perhaps if your Maximum voltage setting was too low, the temperature compensation couldn't raise the voltage high enough when the batteries were cold to charge them all the way.
On my first solar setup I learned how to ruin a deep cycle battery that got cold with a controller that had no temperature compensation. That was a small system in an RV with single battery but taught me a good lesson !
When the batteries are cold and the temp compensated absorb voltage raises , I don't think that translates to using a lot of extra water than normal.
Larry