L 16 problems

peter

I'd appreciate any help or suggestions. I have 12 L16's wired for 24 volts in three strings for my off-grid home. I have always thought that I have taken good care of them, following good eq and watering cycles and recharging to full at least once a week. A few months ago the water level did dip low enough to expose some plates. But this didn't seem to have an adverse effect. I have two strings that are acting weird. I eq'd just those two strings last week and now that they are back on line they have slowly lost power. (my hydrometer readings show that they are nearly dead. These batteries are about five years old. All of the charging parameters appear to be correct and the trimetric is definitely not reading the right percentage of power compared to the hydrometer readings. Are there any tricks to revive them or is it time to buy new ones?

Solar Guppy

Re: L 16 problems

peter wrote: »

I have always thought that I have taken good care of them,

SNIP

A few months ago the water level did dip low enough to expose some plates.

You didn't take good care of them as its takes months to boil off enough water to expose the plates, which simply means you didn't check the cells regularly. Once you expose the plates, your battery's usually are toast, add in they are 5 years old and your probably end of life in charge/discharge cycles which is typical about 2K cycles

Having parallel strings also make it near impossible to keep all the strings balanced and properly charged, so when a string isn't getting charged, the other bank takes the full charge/discharge and has an early death.

Its not good to have strings with different ages either, the new batteries will take the brunt of the charge / discharge, the old battery's being starved of proper charging and will slowly die.

peter

Re: L 16 problems

What would be a better way to wire the batteries?

peterako

Re: L 16 problems

Please provide more information like eq. voltage, end voltage, resting voltage.
Maybe your hydr. meter is dirty.?
What is the connecting diagram meaning provide photo or drawing from the setup, this because in a serie parrelle setup, if you make a connecting mistake you load on serie more than others.

greetings from Greece ( other Peter )

peter

Re: L 16 problems

eq voltage is 31 for two hours, bulk voltage up to 29.6 volts, rest is 27 volts. The wiring scheme is four strings with batteries in the string wired positive to negative. A main wire goes from the negative post on each strings to the next string and then to the charge controller. Same thing with the positive. My family is from Samothrace originally.

peter

Re: L 16 problems

I'm sorry--three strings with four batteries in each.

audredger

Re: L 16 problems

Peter, The "best" is to have only one string or bank. Assuming your L-16's are 375ah then you have 1125ah total. a better choice would be to go to 12- 2v (L16RE-2V) in one string 1110ah or, 6- Surrette 4-KS-25PS 1350 Amp Hour, 4 Volt Solar Battery for a total of 1350ah @ 24v.

If you must run multiple banks, I do (24 L-16H's @ 24v), then the inter-ties between batteries all need to be the same length and same gage, the power cables, both positive and negative, need to be the same length and same gage and should go to a common point, bus bar, where the power to the inverters and from the chargers all take off. Each bank should also be fused.

When you check the water, you need to check every stinking cell! I had one cell in one battery go west on my system which in turn caused all four batteries in that bank to go bad! I was only checking one cells in each bank. I missed that one bad cell until it had done irreparable harm. I removed the four batteries in that bank and took them to the battery store, they charged them individually and discovered the bad cell! Being cheap, I bought one new battery and put the bank back into service. The three old compromised batteries proceeded to degrade rapidly, within days, and took the new battery with them!

In the summer, I check the water every week, high temps & high charge rates = water loss. Yes, I check every stinking cell, all 72 of them!

Batteries need to be maintained! I don't care whether you have LFP, LFYP, FLA or AGM's; they all must be maintained. Different maintenance and different degrees of maintenance but maintained non the less. Otherwise, open your wallet, wipe your butt with Grants or Queens, your choice, and flush!

When you replace your batteries, replace ALL of them! One large bank is preferable to multiple smaller banks.

If you would like; I will post some picture of how to wire a "balanced" six bank system..... it was a lot of work!

BB.

Re: L 16 problems

In order to have a balanced current through a battery bank with parrallel strings--you want to wire your battery bank such that every battery in the string has the same mount of wire (length/resistance) to the common bus point/load to ensure each battery/string takes its share of the load/charging.

Here is a good explanation about wiring a bank:

http://www.smartgauge.co.uk/batt_con.html

-Bill

peter

Re: L 16 problems

I have changed positions of my batteries once per year in the strings to avoid any damage to individual batteries---but the wiring into a common buss bar makes more sense. Thanks for the info. Should I pull the bad strings off line right now until I can afford a new bank of batteries?

BB.

Re: L 16 problems

The answer is probably yes...

If you have an open cell--then the string is not taking current and is useless.

If you have a shorted cell--then that cell is taking down the rest of the bank--worse than useless.

If you have a sulfated bank and/or failing cells (cracked, active material shedding, hard sulfate crystals that don't accept charging current, etc.)--just a useless string and is not adding to the function of your overall bank.

You could take the string(s) off-line, identify any bad cells/batteries and remove those from service... Take the rest of the batteries and reassemble a usable strings, or use the "extra batteries" as charged spares if others in the on-line string fail.

-Bill

audredger

Re: L 16 problems

Yes peter, pull the bad banks now! If you have or can borrow a 6v charger, charge each battery. Let them rest for a couple of hours and check the SG of each cell. You may have enough from the two "bad" strings to assemble one "good".

mike95490

Re: L 16 problems

Sounds like you also need to do a load analysis, and see if you should change anything.

From that many parallel strings, I'd say you should be running a 48V system, which would mean new inverters, but if you are trying to string too much in parallel, the problems will keep coming back.

Are your loads lighting? HVAC, cooking, yard lights? Consider replacing some appliances (fridge) with EnergyStar units.

niel

Re: L 16 problems

i'd be curious as to what you used to charge such a huge battery bank and was it at least at a 5% rate of charge? i do believe though that trojan specs 10-13% charge rates and is quite allot of current.

peter

Re: L 16 problems

I charged the entire bank with the generator (5000 watt) and my (10) 175 volt mitsubishi's today and then pulled and disconnected all of the cables from the bad strings. My system is now running off of the 4 good L16's. I am going to see which of the individual batteries in the bad strings lose voltage by tomorrow morning and check them with the hydrometer for any differences between them. they are all sitting at rest and holding 6.4 volts right now. As far as the loads that my system runs - water pumping from well (110 volt grundfos) laundry, dishwasher, tv computer, lights and small fridge.
Thanks, Peter

mikeo

Re: L 16 problems

As far as the loads that my system runs - water pumping from well (110 volt grundfos) laundry, dishwasher, tv computer, lights and small fridge.

I suspect depending on usage of your loads that you are cycling the battery bank pretty heavily. Five years on L16's would be a good life when cycled a lot even if maintenance is perfect. I suspect one or more of your aging batteries have failed in a string and pulled the good batteries down. That would cause the good cells to overcharge hence the high water usage beyond normal that caused the exposed plates. Hopefully you can pull two good strings out of the three and limp along until you buy a new battery bank. You might consider a rebuilt 24 volt forklift battery at around 1200 amp/hours 20 hour rate to replace your current bank. I was able to get my 940 amp bank for around $1200 delivered with a 1 year warranty from a major supplier GNB.

peter

Re: L 16 problems

Gets a little weirder. My "good string" starts to lose voltage as soon as the sun goes down and are all very hot in the battery box. I start to check voltages across the posts of the individual good batteries and I find one that is way lower and two of the cells are low form my hydrometer reading. Maybe all of the other batteries are good and this one bad one was not allowing power to flow through the string which would explain why this string looked so good even when checking it in the morning? I threw in one of the "bad string " batteries and voltage is back up to 25 and running fine.

BB.

Re: L 16 problems

The problems between shorted and open/sulfated cells can make things confusing... You may luck out and find that only a few batteries are "failed"--and you can get the rest of the bank working OK for now.

-Bill

peterako

Re: L 16 problems

Yes replace it is clear that the battery strings where not loaded charged on the same level. So repairing or using tricks to bring back online is a solution but whitout any warranty from success.
Please make sure that also every battery string has its fuse.

Greetings from Greece8)

peter

Re: L 16 problems

Thanks for all the help. This morning I have discovered that it seems only one battery is bad. I have eight on line and three charged batteries for back-up. I'll give this a few days and see what happens. I also re-wired so that the positive and negative of each string go to a common buss bar and then to the charge-controler/inverter. Peterako, I don't have fuses on the strings--what type should I get for this?

BB.

Re: L 16 problems

Here are some simple fuses and holders:

Inverter Fuses & Breakers

-Bill

audredger

Re: L 16 problems

I used these http://www.blueheronmarine.com/Inverter-Terminal-Fuse-Set-150A-7410 only 100amp

Bus bar: http://smg.photobucket.com/albums/v468/audredger/Battery%20Bank%20Rewire/?action=view&current=DSCN0050.jpg

Fuse in place: http://smg.photobucket.com/albums/v468/audredger/Battery%20Bank%20Rewire/?action=view&current=DSCN0054.jpg

I like the fuse at the battery, protects the wire!

peter

Re: L 16 problems

I'll have to get some fuses like that. I have been thinking, Maybe 8 l16's is a better match with my system right now since I only have ten 175 watt panels. I realize that the batteries are old but they reached full charge with the sun in about three hours and have been on float since then and we're doing laundry. With twelve batteries, I rarely saw the system get to float by itself except in the summer.

Solar Guppy

Re: L 16 problems

Getting to float is not an indicator of the charge stored. Old battery's get higher resistance and don't take the charge, they go to float very fast, a common misunderstanding