Acquired Falling apart off-grid system, need advice

[OzSolar]

That may only be accurate with starting batteries. I don’t know - just that resistance load testers seem to show low capacity for deep cycles vs starting batteries which have thin plates to make 600A cranking demand on starting a car.

No part of my suggestion was to test capacity. It's a pass/fail test.

So if Solar lead acid batteries can survive Vermont winters I’m totally not going to red tag OP’s system that’s working still.

I disagree. Just because it hasn't already had a melt down doesn't mean it's not about to.

Here's some reasons I would red tag the entire system immediately.

-a battery cable corroded in two with one end just flapping around in the wind waiting for something with feathers to bump it into another battery terminal
-several more severely corroded battery connections about to fall apart
-no battery box so countless exposed connections waiting for some unsuspecting person or thing to get something conductive across them
-no class t fuses on the inverter homeruns so there's several hundred(?) feet of wire with no overcurrent protection
-no means of over current protection the PV positive wires directly fed to the batteries so there's another several hundred feet of wire with no overcurrent protection.

I'll stop there.

 

[Bobert]

it’s hard to beat free. If it was me I would make sure all of the batteries had electrolyte clean all the connections and replace any bad cables. It’s possible you may be fine with what you have. Get what you need to maintain your bank. Be sure you are being safe and the education will be worth the effort with the possibility that you could get a solar system thrown in for “free” I can’t see what over current devices are hidden behind the junction boxes but you should make sure proper safety is in place.

 

[John Frum]

it’s hard to beat free. If it was me I would make sure all of the batteries had electrolyte clean all the connections and replace any bad cables. It’s possible you may be fine with what you have. Get what you need to maintain your bank. Be sure you are being safe and the education will be worth the effort with the possibility that you could get a solar system thrown in for “free” I can’t see what over current devices are hidden behind the junction boxes but you should make sure proper safety is in place.

Free can be a honey trap.

 

[RCinFLA]

Long term float charging on lead acid batteries can corrode positive plates grids causing high internal resistance for battery. Long term float charging without any periodic discharging can stratify acid and water in electrolyte degrading the lower sections of plates that get exposed to higher acid concentration. Absorb charging gas bubbling of electrolyte stirs up the electrolyte preventing stratification of electrolyte acid and water.

Golf cart batteries are particularly vulnerable to this.

If off grid system, there is typically enough daily discharging and recharging to prevent too much positive grid corrosion.

Most common failure modes for lead acid batteries are 1) hard sulfation of negative plates due to lack of fully charging over long time period, 2) corrosion of positive plates grid due to continuous float or overcharging, and 3) allowing electrolyte to drop below plate edge surface. First causes drop in capacity, second causes high resistance causing a lot of voltage slump with load current, third causes cell shorts.

During charging, negative plates give off hydrogen gas and positive plates give off oxygen from splitting water (H2O) in electrolyte. This causes the water loss and dropping of electrolyte fluid level in battery. Do not allow electrolyte to drop below surface edge of plates. This will damage the dry exposed top area of plates and can create cell shorting. Need to constantly replenish water loss in electrolyte due to charging and requires constant maintenance in off grid systems. Keep a lot of jugs of distilled water on hand.

This is the reason positive plates get corroded from being bathed in oxygen. Also need to be careful of hydrogen and oxygen escaping gases during charging in a confined space that can create an exciting event.

 

[12VoltInstalls]

No part of my suggestion was to test capacity. It's a pass/fail test.

Right. And often a deep cycle battery will fail a resistance load test because they are designed around cold cranking amps testing.

Just because it hasn't already had a melt down doesn't mean it's not about to

That’s a huge leap!

battery cable corroded in two with one end just flapping around in the wind

i believe he came here to receive guidance to up-maintain and secure his neglected system. So all your points are already in his mind. The train left the station.

I know that I sound disagreeable. Sorry for that. That’s not my motivation.

He has a solid, functioning system that he wishes to expand his knowledge to get the maintenance up to date and insure the system is dependable and safe and that is the perspective I’m using to evaluate what I would do in his circumstances. I’m trying to avoid writing his checks for him from my armchair while he goes broke with his fantastic brand new 50kWh battery bank

 

[justgary]

I’m trying to avoid writing his checks for him from my armchair while he goes broke with his fantastic brand new 50kWh battery bank

I agree with everything you said, except that I think that every forum member (of any online forum) has a duty to spend the money of other forum members. That is truly the reason that people join forums; they can't figure out how to spend their own money!

OP - Remember the tips from @sunshine_eggo and record your settings first. Then you can shut down the system for maintenance. You may want to do it in stages so that you can turn it back on as required for power. Be very mindful of cable ends as you loosen them. A sheet of plywood over the batteries near where you are working might help prevent a short.

 

[Nobodybusiness]

It’s working now. Why is a little maintenance time a bad thing?!!?‍

I don’t think it’s a lost cause. I think since it’s working now:

…that a little preventative maintenance will give quite a bit more service life.

Because it’s working now

… there is no triage.

That’s like my lawyer’s full time residential off grid system here in Vermont: one battery change in 25 years. So if Solar lead acid batteries can survive Vermont winters I’m totally not going to red tag OP’s system that’s working still.

He asked.
We gave our opinions based upon our past experiences.

Time will tell.

 

[OzSolar]

Right. And often a deep cycle battery will fail a resistance load test because they are designed around cold cranking amps testing.

That’s a huge leap!

i believe he came here to receive guidance to up-maintain and secure his neglected system. So all your points are already in his mind. The train left the station.

I know that I sound disagreeable. Sorry for that. That’s not my motivation.

He has a solid, functioning system that he wishes to expand his knowledge to get the maintenance up to date and insure the system is dependable and safe and that is the perspective I’m using to evaluate what I would do in his circumstances. I’m trying to avoid writing his checks for him from my armchair while he goes broke with his fantastic brand new 50kWh battery bank

I simply offered my advice, supported by sound reasoning and 30+ years in the industry. I shared what I would do when I get called into a system in this state. Believe it or not, I'm very careful to balance the cost of fixing it "right" the first time vs. the odds of hacking it back together just to keep the first cost low but getting numerous expensive callbacks that I'd have to charge the customer for.

 

[Mattb4]

I simply offered my advice, supported by sound reasoning and 30+ years in the industry. I shared what I would do when I get called into a system in this state. Believe it or not, I'm very careful to balance the cost of fixing it "right" the first time vs. the odds of hacking it back together just to keep the first cost low but getting numerous expensive callbacks that I'd have to charge the customer for.

Perspective of a person hired to do a job versus someone doing it themselves. Your approach would give you a good reputation and repeat business. It is like giving advice on a Forum. It is best to try to stick to giving safe ways of doing things versus what I who might have more experience and knowledge can get away with.

Now hold my beer.

 

[12VoltInstalls]

Be very mindful of cable ends as you loosen them.

Rubber table- or chair-leg feet; big ones; taped on to the terminals one by one as you take them off is a good way of doing this. Hard to find but I got some somewhere once- square, and big enough to fit.
I only have eight batteries and haven’t had an “event” but I’ve scared myself a couple of times thinking a little drop accident was going to make something happen. I use red tape on pos(+) and white on neg(-) to keep my ADD in check. Black on neg(-) would be fine, too.

 

[sunshine_eggo]

??

Welcome to the forum.

Oh my, I wish I there. Being on sites like this resurrecting orphaned systems is my happy place.

I'm with you on this, but for a noob, getting something of this scale right and succeeding is enough to turn someone off this and future efforts completely.

Yes, you need to turn off all the power sources. I don't see any disconnects at the charge controllers. Hopefully there's some combiner boxes at the array.

If it was me I would skip initial SG testing by using one of these battery testers from Harbor Freight. All it's going to do is tell you if a battery is good or bad, not how good. Bad = immediately falls into the red zone on the meter the instant you push the button and needs culled. Anything that doesn't fall into the red zone can put in the "maybe" pile for SG testing later following the below instructions. If you use my method first you'll get down to only 25,000 or so cells to test. LOL

I almost went there, but C and D grade batteries are likely to fail. In my experience, batteries falling in those bins with consistent but low SG are good candidates for improvement.

Keep in mind you only need four good batteries to get to your 24v, not saying that's ideal but I'm making sure you get the theory. If you could end up with 12-16 good batteries you'd have about ~10-15 usable KWH which might be all you need while you figure out what you're trying to do with this system overall.

Truth.

Also you don't have to hook all the solar charge controllers back up initially. If it was me I would use one or two them dedicated to resurrecting the iffy batteries after got the system up and running again in a bare bones triage mode.

Good advice. I should have included this.

 

[sunshine_eggo]

It’s working now. Why is a little maintenance time a bad thing?!!?‍

I don’t think it’s a lost cause. I think since it’s working now:

"working" is subjective. My 4S2P T-1275 Trojan bank was working, but when I scrutinized it, I discovered one string was in horrible condition. Zero batteries from the one string are recoverable. 2-3 cells deaths per 12V. They were neglected due to my infrequent time on site, but they likely weren't neglected to the degree these were.

The OP does not appear to have any experience with this or similar systems and wouldn't know what to look for. Just because alarm bells aren't going off doesn't mean something is working like it should.

Running every one of those batteries for any significant period of time with exposed plates may not render them completely inop, but they should not continue to be used.

…that a little preventative maintenance will give quite a bit more service life.

Preventative maintenance only works on something that can be fixed.

… there is no triage.

That’s like my lawyer’s full time residential off grid system here in Vermont: one battery change in 25 years. So if Solar lead acid batteries can survive Vermont winters I’m totally not going to red tag OP’s system that’s working still.

This is a false equivalence. Cheap Interstate batteries with overwhelming evidence of serious neglect can't be compared to your isolated case.

Concerning your lawyer, 100% certain that those batteries were very well maintained. 90% certain those batteries were not regularly discharged to 50% - likely only 70-90% SoC. 1000% certain high quality batteries made 25 years ago would have lasted longer than "high quality" batteries made today. Not sure if you've noticed, but lead-acid in general isn't what it used to be.

 

[400bird]

It seems the OP is gone. Too overwhelmed by that battery bank.

Oh my, I wish I there. Being on sites like this resurrecting orphaned systems is my happy place.

I'm not buying it. You just want to go to Hawaii ?

 

[sunshine_eggo]

Shuddering at the thought of 144 SG readings... Alternate easy mode:

Add distilled water to ensure plates are covered.
Fully charge system.
Remove all loads and chargers from battery - physical disconnect if possible.
Remove at least one cable from each 4S string to break all parallel connections. See red "X"s:


Measure voltage of all 6V after 3-7 days.
Anything under 6.2V is likely unusable or needs recovery efforts.

 

[OzSolar]

He has a solid, functioning system

I say closer to timebomb. I'm not going to debate "how solid" or not all of that unprotected wire between the batteries, charge controllers and inverters is. You can keep trying to. Just one thing goes wrong and that entire battery bank will be dumping energy somewhere it shouldn't be until the fault clears or the battery bank is dead. ??

Now hold my beer.

Will do! And your truck keys as well, just in case...

I'm not buying it. You just want to go to Hawaii ?

You're on to me. Ha. Haven't been there since my Navy days but I've already got a month of "work" in Puerto Rico lined out plus another gig in southern Patagonia before before it turns back to winter down there to do so this system will have to sort itself without me this time.

 

[12VoltInstalls]

lead-acid in general isn't what it used to be.

I have noticed

 

[12VoltInstalls]

unprotected wire between the batteries, charge controllers and inverters

Those are problems, yes.

I’d still go through it and correct things one by one. But that’s me; other people have different tolerance.

Concerning your lawyer, 100% certain that those batteries were very well maintained. 90% certain those batteries were not regularly discharged to 50% - likely only 70-90% SoC. 1000% certain high quality batteries made 25 years ago would have lasted longer than "high quality" batteries made today

Big giant 6V golf cart batteries. 4. First set went about 15 years. I don’t know what she’s done recently but I’d say she’s about due for another swap if she didn’t do it already.
I think she hammers the batteries pretty hard most winters. Iirc she at least doubled or maybe tripled the panel watts soon after the battery swap with two 1.4kW? arrays. No grid for a mile or two, but has a phone line run from the road that carried a lightning strike. The event produced new panels and equipment because the cordless phone wallwart backfed everything and smoked it. Interestingly, the mile+ phone line itself survived.

Anyway, I see your points- though you may recall my advice to start with was for him to get a hydrometer and evaluate. I need to find mine. My batteries have done a strange thing I have never heard of ever: after changing from a bad 8P battery arrangement to a balanced 4P2P my electrolyte loss over time became basics zero. Typically I’ve lost water over winters but I didn’t last winter. I topped up a couple in April-ish but over the summer all batteries lost no fluid level !! but I’m not holding 13.1V anymore. Unloaded they drift down to 12.6 or so. A good boy would hydrometer them every couple months:|

I say closer to timebomb

A matter of one’s outlook.
People trade out vehicles because they need a new timing chain, or the motor smokes a little, or sometimes even when the brakes are bad. Because they think it’s a sign that the vehicle is worn out, like a pair of shoes. I see things like that as basic maintenance to get another 150k-miles out of it. You see a disaster in that system, I see stuff I can fix. (I’m buying a Grand Cherokee today with a knocking, essentially about-to-blow motor. I have bought a replacement motor with 160 compression. I’ll have a nice clean comfortable rig for 10 hours labor and 1/5 of the cost of buying off marketplace. The seller thinks of it as a lost cause. I see it as an opportunity.)

 

[KITROBASKIN]

12VoltInstalls gets my vote.
I just looked. The thread starter was on the forum a little while ago. Seems like he should be asked if he has a way to measure voltage, continuity, and is willing to fill the batteries above the plates. If distilled water is scarce, can he use clean rainwater?

I would do a basic brushing/cleaning of the terminals and the surface of the batteries, checking for loose connections. If it was crystal clear where the wires broke, I would use something like the copper Burndy SERVIT Split Bolt connectors to connect them again. Let it roll for a while and see what the system does. Wish I had this plopped in my lap, but understand others would not.

 

[KITROBASKIN]

After a while, I’d remove the connections one at a time to each battery, checking voltage. Taking out the fallen will hopefully buy time to save up for more batteries or flip the property. And the owner needs to know how to keep the proper strings for proper voltage. Every month I would check fluid level, being careful at all times to not complete unintentional sparky circuits.

 

[OzSolar]

I would use something like the copper Burndy SERVIT Split Bolt connectors to connect them again.

What?? This is a poor and total hack suggestion. The only solution is to make a completely new battery cable.

The OP knows they have a mess on thier hands, per the title of the thread. (take this moment to refer back to it).

You can turn this into a popularity contest if you want but in the interest of helping the OP let's just stick to the facts and not offer votes.