Breaking the bank

[Lowdown3]

Well it sucks but it was getting to be that time again.

This go around we got about 8 years service out of our battery bank.

First time around we had a "friend" that thought he knew everything "help" us PM the batteries one time. I reminded him before he started that the water only needed to be 1/8 of an inch over the plates. "I know dude!" was the reply. Honestly it was my fault for letting him anywhere near them.

10 gallons of water later, every battery was filled to the TOP with water!!! :mad: Needless to say it wasn't long before bad cells started showing up.

Needless to say on this second batch I haven't let anyone else near it.

When a battery gets a bad cell, it will drag down all the batteries near it, kinda "siphoning" power off from the nearby batteries. Maybe someone more technical can explain it better than that for me ;)

Needless to say, it's like having a length of chain that was super strong, but now you have a weak link. Worse than that, you have a weak link that saps the strength from the other links by it.

Sometimes this problem is hard to spot.

Here's a few signs and symptoms I've seen the couple times I have had these-

*You'll notice that even fully powered your system doesn't seem like it goes as long as it used to on this much power. In other words, if your normally have no power outages during days of full sunlight then all the sudden at 5pm your out of power.

*Disconnect battery connections isolating each battery from others and take an individual voltage reading. I've seen really bad batteries jump around like crazy, going from 4.5 to 5 to 6.3 to 7.8 in a 10 second period. Not ALL bad batteries will do that, but that's a big indicator that their is trouble with that battery.

*Your system voltage reads fine-WITHOUT A LOAD, but once a load is put on the system, even a small load, the system voltage drops DRAMATICALLY. Let's say your system voltage reads 26.7 without a load. You apply a 3 amp load to your system and it drops down to 23 volts in a matter of minutes.

These are all clues but not hard fast rules.

Once your using your system, living with it, regularly, you'll kind of get a "feel" to how things works. I know that sounds silly but it's the best way I can explain it.

You can't leave a battery with bad cells in your bank. Start by disconnecting any series and/or parallel connections you have on the battery. Once isolated, check the voltage and the water level. Often times a bad battery will suck water down like mad. Also I've noticed at times that the battery CAN feel a touch hot compared to others around it.

A lot of auto parts stores will offer free testing on batteries brought in. This can be a PITB when your talking about larger batteries and loading up a couple dozen of them, but it's usually a sure fire way to know for certain that a battery is bad.

I've heard that a product called "EDT" will "restore" old batteries. I did NOT find this to be true. I purchased a bunch of the crap and used it exactly as the directions described.

The batteries are the weak link in your AE system and the items that will need to be replaced from time to time.

Some things you can do to prolong battery life-

1. Set the low voltage disconnect (LVD) on your inverter to a higher setting. For example, the default factory setting on our inverter for a 24 volt system is 22.1 volts. That's pretty low voltage actually.

I reset it to 23.1 Doing this means the inverter will not LET the battery bank get discharged past that point. The inverter simply shuts down the system then. Conversely a decent inverter would automatically start a genset for you then also. I've chosen not to use that feature for various reasons.

Making it to where your batteries purposely CANNOT be discharged very far is another way to prolong their life.

Good battery maintenance including proper watering, equalization charges, etc. all helps as well.

I've always heard people say "well you should be able to get 10 years off those batteries" but upon further questioning, most are talking about using them for a backup system, not a system in regular use.

AE and tech guys- what other advice can we give folks about battery maintenance?

[Sanction]

I'm toying with a device I made my self from plans on the net called the Bedini Motor. Created by John Bedini. Although it doesn't charge the batteries the way it's claimed to do, it does have a very interesting result. It seems to condition the batteries. It de-sulfates the plates in the batteries and raises the voltage level. I have actually rejuvenated batteries back to life again. Running this device on your battery bank would prolong there life. I also recommend you purchase a second battery bank and do a switching back and forth charging the bank not in use. One of the worst things you can do is drain and charge at the same time. I hope that points you in the right direction. I will be posting a tutorial on my site on how to build the Bedini Motor, and the different ways it can be wired. http://modernhomestead.homeip.net:8080
It isn't posted yet but now that the bugs are worked out of the site I will be loading content.
Good luck!

[Lowdown3]

I'm talking about 20 L16's with a current retail price of about $300. each, having two separate banks isn't an option for me unfortunately ($6,000. each X 2 = $12,000)

An equalization charge acts in the same way you are describing the de sulfator (I think that's what they are called). You should EQ your batteries at least once a month. MPPT charge controllers will do this automatically and standard charge controllers like C40's will do it at the push of a button. On the AC side, your inverter will run and manage an EQ charge via your genset.

[Rmplstlskn]

You mean you can't just scavenge batteries from junk vehicles like they do on "The Colony?" lol!

My only tip is: Use DISTILLED WATER to refill a battery... not De-IONIZED! A long story of when I was an Operator at a large water plant decades ago and they were using De-IONIZED water to fill all their battery banks... Uh, IONS are NEEDED for proper battery operation... hello! I can only imagine how much money was wasted buying new batteries all the time...

Rmpl

[trkarl]

When first commissioning the bank it should be equalized until the sg stops rising. Then label each cell and take a sg reading and record it. This gives you a base line to compare to in the future. After every full equalization the sg of each cell should be recorded. This way you will be able to catch a problem early on.

If you find that after what you think is a full eq that one cell's sg is slowly dropping each time then you know most likely that cell is being deficit charged and will be the first to cause a problem down the road. You may need to eq longer or set the absorb voltage higher or for a longer duration etc.

[Lowdown3]

When first commissioning the bank it should be equalized until the sg stops rising. Then label each cell and take a sg reading and record it. This gives you a base line to compare to in the future. After every full equalization the sg of each cell should be recorded. This way you will be able to catch a problem early on.

If you find that after what you think is a full eq that one cell's sg is slowly dropping each time then you know most likely that cell is being deficit charged and will be the first to cause a problem down the road. You may need to eq longer or set the absorb voltage higher or for a longer duration etc.

Excellent post! Thank you!

I have a heckuva time reading those SG gauges, any recommendations on a good one?

[Sanction]

I'm talking about 20 L16's with a current retail price of about $300. each, having two separate banks isn't an option for me unfortunately ($6,000. each X 2 = $12,000)

Well, I don't know your power requirements, but if you run fine on half the batteries you could split the bank and alternate the charging that way. It's just a suggestion, charge and discharge at the same time sulfates the plates quickly. All though I will be using what ever batteries I can get my hands on, the proper care will make all the difference.

[Lowdown3]

Definitely. And to be honest, I'm more than happy getting 8 years out of these, considering daily use. However if I can squeeze that into 10 years I'd be more happy ;)

[trkarl]

Excellent post! Thank you!

I have a heckuva time reading those SG gauges, any recommendations on a good one?

Here is the one I use.

http://store.solar-electric.com/frhdprhy.html

I have a couple as back up also because they are delicate and you will end up breaking one. I have.
Note it is also important to get one with a thermometer in it to compensate for the error in readings based on temp.

Much higher or lower than 77 degrees and the reading can be off by 5 or more points. I know this doesn't sound like much but over the course of several years the results add up.

Also as far as your bank goes if you are going to parallel a couple of L-16s why not just buy one string of industrial batteries? You should get a lot more life out of them and maintaining one string is much less time consuming than several.

But then again if one cell fails then your string fails. That is why I also have a 12v string of the same batts as my 48v string and I cycle it. This way if one cell fails I can remove it and replace it. Always think about back up. In a shtf there may not be any.

[monkeybird]

How long can you store a battery bank that has not been used. Do they wear out?

[trkarl]

How long can you store a battery bank that has not been used. Do they wear out?

They eventually wear out. A lot of people with hybrid AE systems have their batts on float until the power goes out. While usually they will have a longer life timewise than if you cycled them every day, they usually won't have the same cycle life as if you cycled them every day. One thing you need to watch if you keep them sitting without cycling is they will stratify. That is the heavier acid will separate from the water and the bottoms of the plates will disintegrate. This is why they need to be cycled every so often.

The best thing to do if you want to store them is find a manufacturer who will sell them to you dry. Then store them in a cool location. Also you will need to store the electrolyte.
Then you would need instructions for activating them when you want to start using them.

Surrette sells them dry on special order. Here is how to activate them http://surrette.com/content/tech-faqs#dry

[monkeybird]

Thanks for the link. The issue of not having battery power for your Solar System if TEOTWAWKI is truly TEOTWAWKI. While 8 years sound like a long time, what do you do afterward. Having backup batteries that are not yet activated sounds like a great solution.

[Lowdown3]

Thanks for the link. The issue of not having battery power for your Solar System if TEOTWAWKI is truly TEOTWAWKI. While 8 years sound like a long time, what do you do afterward. Having backup batteries that are not yet activated sounds like a great solution.

Yes that's definitely an issue.

One thing we have been able to do even with the bad batteries, is to do our larger power loads (like loads of laundry) when the sun was up, the power showing good (cause more power was going in than coming out with the bad batteries). However once it gets to be about 5-6 pm it's all done.

In the PAW, I would first do like I said in the OP- break the bank, go through and try to route out the bad battery or batteries. That being said, in a 24 volt system, one bad battery means you have to take out a string of FOUR (six volt batteries). If you had FIVE bad batteries it would mean taking two strings of four out for a total of 8.

If the bank was completely tanked, you could use it as a short term, i.e, when the sun is shining, storage tank. With the sun up and a lot of power coming in, the bank fills up quick, then you would have to do pretty much ALL your electrical loads during the day while the sun is shining. In that way, you'd be kinda using the battery bank as a pass through versus it's normal use as a storage vessel.

Here again we see the old Russian concept in action- "There is a certain QUALITY about QUANTITY."

In other words, if your bank is only 8 batteries in a 24 volt system and you have one bad batt, your down to FOUR batteries. It's for this reason I'm seriously considering expanding our bank to 24.

Thanks for putting that link up TR. I've asked numerous times about finding "dry" Trojans and even the state distributor thought I was nutty for asking. It's evidently not that common a thing.

[SamT]

In a previous life I had to perform Regularly Scheduled Mainenance on a large battery bank. 6 KW hours large.

Safety First:
Safety shield and goggles for your face and eyes!
Nitrile or Rubber gloves!
Acid resistant apron! Chemists, rubber, or baking soda water soaked leather.
5 gallon bucket of baking soda water!
Eye rinse facilities!
Fire extinguisher!

Monthly Checks:
Corrosion; Pull all terminals, insure Battery terminals and inside of connector is shiney metal. Insure no corrosion on cable to terminal connection. If corrosion is present, Clean off connection grease with brush and hot soapy water or solvent, dip in agitated near boiling water saturated with baking soda until no more bubbles are found. Thoroughly work terminal grease into exp[osed cable and connection area. Check cable resistance connector to connector with ohmmeter set at 1 ohm scale. (I forget the allowable resistance. Check several new cables, (shiney to shiney,) to determine proper resistance. It should be around .03 ohms IIRC.)

Cells; Wipe tops of batteries clean. Gently rock battery for three minutes to agitate electrolyte. Pull cell caps and carefully wipe with clean rag away from opening insuring that no debis falls in cell. Add water to bring level up to bottom of filler neck. Replace caps and gently rock battery for three minutes. Check electrolyte with hydrometer. When electrolyte is at proper density and fill is at or above bottom of filler neck, add water to bring level to near top of slot in filler neck. If large disparity of electrolyte density between cells, replace battery.

Water, in order of preference; Distilled, RO, Deionized, Sediment and Charcoal filtered, Sediment filtered cooled water from hot water tap, Sediment filtered potable water, Sediment filtered non potable water, In emergency only any available water.

Perform 6 month and annual maintenance. Perform maintenance on 1/6 and 1/12 of batteries each month.

6 month:
Use resistive or auto parts shop type load tester per instrument directions. Replace any batteries that fail.

Annual:
Remove 1/12 of your batteries to test location and test for extended load life. See "Test Load Setup" below. Replace any batteries that fail to meet your loading requirements. You know that you want your battery bank to provide X hours at Y amps before it falls below your invertor's cutoff voltage, Z, and you have M batteries. For example, If X is 36 hours, Y is 50 amps, Z is 23 volts and M is 24 batteries. Each battery in each bank of 4 must provide 12.5 amps times 36 hours before falling below 5.75 volts. IOW, 450 Amp hours @> 5.75V.

Load Battery at 1/8 total required amp hours, (56.25A from example,) for 8 hours or until Voltage drops below Calculated Z, (5.75V in example.) Note that the assumed numbers in this example means that your battery will be heated by 337.5 watts for 8 hours.

This is a severe test. It will slightly reduced the lifespan each time it is performed. It must be used when it is mandatory that your battery bank must provide its designed load time. If it is allowed that you may be without the use of the B-bank for the time it takes to find and replace that one battery that is drawing down the b-bank, you can skip it.

Finally:
Reconnect cables to batteries using terminal grease on battery and inside connector, coat entire terminal and connector.


Test Load Setup:
Explosion Resistant Barrier; Stack CMUs, AKA cinderblock, to height needed, place 2x2 wood stick in each column of cells and fill columns with sand or dry dirt. Cover with 3/4" ply and place at least 4 CMUs on top. Build 3 sided barrier or use posts to support corners of top not on barrier. The important parts are that this is a soft barrier and will keep material from going vertical and possibly landing you, the operator.

Battery cooler; large washtub or split 55 gal metal barrel. If using flat bottomed cooler, set battery on dowels to allow water flow underneath. Keep water level at 1" below battery top. Use easily visible temp guage to insure water temp is under 140* for entire test.

Test Load; Large washtub or open top 55 gal barrel. Using a method that will allow you to lower and fix at a variable depth, attach with insulators, a 2 sqft steel anode plate above the barrel. Attach rated battery cables to the barrel (-) and the anode plate (+) insuring a good shiney metal to metal contact. Use plenty of terminal grease or Copper Coat brand automotive gasket cement. Fill the barrel with water and add table salt while stirring vigorously until no more salt will dissolve. Using hot water is prefered. Let cool before using Test Load. You won't have to replace salt unless you notice a build up of deposits, then clean and start over with fresh salt and water.

Instrument Center; Mounting plate, wood or plastic, non conductive. 2 copper bolts w/ copper nuts and washers to thru connect cables to battery and to load. Voltmeter and automotive slip over type ammeter. Connect voltmeter between cable connector bolts, watch the polarity! Slip ammeter over one cable and fasten all to mounting plate so everything will stay in place ;) All connections should be permanent except to battery under test.

Usage; With Anode plate above water, place battery in coolant, connect cables to battery. Slowly lower anode plate into test load until ammeter shows required load current. Fix in location. After 15 minutes, raise anode plate out of water and check all connections for heating. Lower anode plate and continue test. After one hour, raise anode plate out of water and recheck connections and battery temp. Repeat half way thru test and check water levels. You can skip this if you can observe water temp guage in cooling system. Keep a weather eye on the temp as well as the voltage meter.

Replace or not???? I would suggest that you purchase a nonfilled replacement any time the battery did not meet the full 8 hour test, but leave the battery in service. Mark it for the total amp hours it provided the required voltage, then replace it as soon as you see that it will be needed more than that. After the "emergency," put it back in service til it dies and store the slightly used replacement.

Properly servicing a 24 unit battery bank takes about 8 hours. If you are "Manpower challenged" I would perform it on 6 week/9 month/18month intervals or even on 2/12/24 month intervals, but no less. You can also load test more than one battery at a time, as long as you provide sufficient cooling. The load barrel can handle any load that doesn't actually boil the salt water as long as you monitor the level and current and the cables can handle the load. Pay special attention to any connections for heat level.