Equalizing Procedure Questions

OffGridMarty

Hi all, I have a new set of Trojan T105Plus batteries (not yet connected) and I have a few questions about equalization. This is my system (in use for 7 years now):

• 4x 12V 190AH Enersys batteries in series for 48V
• Morningstar Tristar 150/60 charge controller with temp compensation in use
• 4x LG 400W 2S2P panels
• Latronics LS3500W inverter

I'll be removing the 4x Enersys batteries and hooking up the 8x 6V 225AH Trojan T105 (Spec Sheet here) in series for 48V. After some researching I think this is how an equalization will happen:

1. System is in float on a nice sunny day
2. Check and fill with distilled water if needed and log SG.
3. Turn off loads
4. Start EQ for 1 hour
5. After 1 hour check the specific gravity for imbalances and do another hour if necessary.

Would it be better to do step 3 before step 2?

Things I've read say to check the SG periodically during the EQ. Should the EQ mode have stopped or am I popping the caps to check the SG with the batteries still in equalize mode and bubbling away?

Bonus Question: Outside of EQ can the SG be checked at anytime during bulk, absorption and float? If so, is it best to check during float? Or even better to wait for float and then shut off the system and check them while idle? Maybe before the system starts in the morning?

I'm using a HydroVolt to measure the SG and will be keeping a log. Thanks for any help!

Photowhit

Yes, Equalize only on a fully charged battery bank.

No need to turn off loads, equalizing takes relatively little energy.

Don't fill with distilled water unless you have exposed plates, you'll want to do that after. Doing it before may make a mess as the electrolyte will become veery active during this time.

I always like to suggest there are 2 types of equalizing (Some companies agree like Rolls)

There is monthly or quarterly Equalizing done for maintenance. Often people just allow there charge controller to do this automatically most will have a setting for this.

OffGridMarty said:

1. Start EQ for 1 hour
2. After 1 hour check the specific gravity for imbalances and do another hour if necessary.

Things I've read say to check the SG periodically during the EQ. Should the EQ mode have stopped or am I popping the caps to check the SG with the batteries still in equalize mode and bubbling away?

This looks like Corrective equalizing, when one or more cell's SG is out of balance with the rest. and it's the proper procedure for that. You can check SG at any point. You may find watermiser caps to allow a bit extra protection for the mist as well as helping reduce distilled water use slightly.

Checking the electrolyte's Specific Gravity (SG) should NOT require shutting downloads, some inexpensive inverters won't be able to handle the higher voltage, but most quality inverter will be just fine. The charge controller will keep the battery at the correct voltage on a fully charged battery. How charging works at the end of this.

Trojan Tips 5 - Equalization is Key to Extending Battery Life and Performance - YouTube

The voltage you are seeing is the system voltage and not the battery voltage. If you are connected to charging or a load it will effect the system voltage.

During charging, there are basically 3 stages of charging, Bulk, Absorb, and Float.

BULK;

First thing when charging starts you will be in bulk, the voltage rises from what ever the system voltage was to a set point, around 14.5 volts. At that point the Charge controller stops the voltage from rising. Higher voltage can damage sealed batteries.

ABSORB;

Once the battery hits the preset point the charge controller keeps it at that point. Your batteries are roughly 80% full. Flooded batteries will start accepting less current at 80-85% full AGM/Sealed may go a little longer before accepting less current.

On many controllers you can set this point, Some will have different presets for Flooded, and sealed batteries, or flooded, AGM, and sealed batteries. 

The charge controller has a couple ways to know when to switch to float, Most inexpensive Charge controller are just timed for 1.5-2 hours. Some will also see less current flowing through the charge controller and shut it down when minimal current is flowing through the controller. On more expensive charge controller. You can set battery capacity to give the Controller a better idea of when to stop. you can also set a longer Absorb time. Or set 'end amps' a amount of amps flowing through the charge controller to stop Absorb and switch to the final stage.

FLOAT;

Once the Controller has determined the battery is fully charged it reduces the voltage to a point where very little current is flowing to the battery. This will prevent the battery from over charging and heating up.

While in 'Float' the charge controller watch for voltage drop, which would indicate a load. If the voltage begins to drop the charge controller will allow as much current to flow from the panels/array to compensate and maintain the voltage. If the voltage can be maintained, the load will in essence be running directly off the array/solar. If the voltage drops below the preset float voltage, the controller may start a whole new cycle if it stays there for a period of time.

The system voltage drop you see at night when the sun goes down is the charge controller moving into a resting mode with no energy to contribute to the system.

The morning voltage may reflect a load present that is effecting the voltage level.

OffGridMarty

Thanks for your reply and useful tips Photowhitt. I've added these things to my understanding:

• Can check SG at any time during the charging and EQ process.
• Don't fill the water before EQ unless plates are exposed (but in best practice the plates should never be exposed)
• Don't need to shut down loads if enough power present for EQ
  
• 2 types of EQ: Maintenance and Corrective

Photowhit said:

Checking the electrolyte's Specific Gravity (SG) should NOT require shutting downloads, some inexpensive inverters won't be able to handle the higher voltage, but most quality inverter will be just fine.

My inverter shows the input voltage range as 42-68V and the EQ voltage of the T105 is 64.8V so I should be fine to leave the loads on during EQ. Taking into account the temp compensation, if I wanted to EQ when they were at 10°C (never likely though brrrr) then my amateur math would be:

0.005 volt per cell for every 1°C below 25°C x 24 cells = .12 rise in voltage per degree below 25°C

.12 x 15 degrees (for 10°) = 1.8V rise in temp compensated voltage

1.8V + EQ voltage of 64.8 = 66.6 temp compensated EQ voltage at 10°C

I hope this is correct, I'm usually bad with the maths.

mike95490

I've got a concern about the battery bank size.  Unless you are using a lot of power during solar hours.  And the inverter is rather large, and may have a huge idle power consumption.  Check out what the idle/standby power is for that inverter.

And remember, a long float charge, can eventually bring good batteries back into balance.  Every EQ cycle has a slight amount of damage that goes along with it, so keeping your absorb time optimized, is much better that just blindly running an EQ every 30 days.

OffGridMarty

mike95490 said:

I've got a concern about the battery bank size.  Unless you are using a lot of power during solar hours.  And the inverter is rather large, and may have a huge idle power consumption.  Check out what the idle/standby power is for that inverter.

Hi Mike, we bought the inverter with the thinking that something oversized for the job should mean that it needs to work less throughout its life. We monitor our usage and don't use much really, mostly when the sun is out. The inverter spec page shows the standby current as 40mA and the "inverter ON-no Load" as 0.33A. We've been using the 190AH bank with this inverter for 7 years and it's been going really well.

mike95490 said:
And remember, a long float charge, can eventually bring good batteries back into balance.  Every EQ cycle has a slight amount of damage that goes along with it, so keeping your absorb time optimized, is much better that just blindly running an EQ every 30 days.

Thanks for the tips. Fortunately we get enough sun that we usually float 2-6 hours a day and I also have a new 3000W array to set up soon too. I've read about the damage an EQ does and plan on only equalizing when the SG is low or out of balance. I've played with the absorb time with the current SLA's and have managed to eek some more time out of them. I'll have to play with it more often with the new batteries though. Thanks for the help!

JRHill

OffGridMarty said:

 I've played with the absorb time with the current SLA's and have managed to eek some more time out of them. I'll have to play with it more often with the new batteries though. Thanks for the help!

There's a lot to be said for using a "bit" higher/longer absorb voltage in your normal, day to day charging IF you take the time to arrive at what works for you by taking SGs and fine tune for your specific system. And you might be surprised that you won't use that much more water. I was able to keep the cells in line with one another to the point that an EQ was only a few times a year and that was just for maintenance and only a few hours.

OffGridMarty

Thanks for your reply

JRHill said:

There's a lot to be said for using a "bit" higher/longer absorb voltage in your normal, day to day charging IF you take the time to arrive at what works for you by taking SGs and fine tune for your specific system. And you might be surprised that you won't use that much more water. I was able to keep the cells in line with one another to the point that an EQ was only a few times a year and that was just for maintenance and only a few hours.

That sounds ideal, and I hope to one day achieve such a high level of battery-fu.

JRHill

OffGridMarty said:

That sounds ideal, and I hope to one day achieve such a high level of battery-fu.

After two banks of FLAs over 11 years with two systems my battery-fu is now battery-never-mind. Thanks to lithium the system is as close to maintenance free as I could ever imagine. Or for the DW if something should happen to me. I still have T105s on the well but when they are done I'll plug the well into the house and be done with a 2nd system. It's really something to be considered if you have some of the same concerns. Once the high and low battery voltages are under control/reliable there's not much to do but squeegee the panels. Which is never. 

OffGridMarty

I researched lithium but decided against it for now. My current bank was $1200 and has lasted for 7 years, and could probably go another year if I wanted to abuse them. This new bank was $2500 and I hope to get 10 years out of them. Maybe after their toast I can upgrade to the Fallout Atomic Home Generator.

What happened with your previous battery banks?

JRHill

OffGridMarty said:

What happened with your previous battery banks?

The first one, all batteries (RE16-A) reached EOL pretty much at the same time with low SGs at 5 years. I traded them to a guy for 5 100' rolls of 60" Red Brand non-climb horse fence. I felt kind of bad that I took advantage of him but he was elated. The 2nd Bank of RE16-B had two blocks with 1 cell in each fail a month apart at 4.5 years. SGs on the rest were holding OK but showing their age. I wasn't going to buy new Trojans so against all advice I replaced them with the cheapest L16s I could find (Intersttate). Their specs had a bit lower Absorb V but needed half again more time. It didn't work very well. After adding the PHIs I ended up selling L16s off in pairs to people with 12v systems.

Photowhit

OffGridMarty said:

I researched lithium but decided against it for now. My current bank was $1200 and has lasted for 7 years, and could probably go another year if I wanted to abuse them. This new bank was $2500 and I hope to get 10 years out of them. Maybe after their toast I can upgrade to the Fallout Atomic Home Generator.

What happened with your previous battery banks?

I'm going into my 12th year on a forklift/traction battery. 12-85-13 (12 cells, 85 amps per positive plate 6 hour rate, 13 plates of which 6 are positive... or a 24 volt 510 ah at 6 hour rate or roughly 660 ah at a 20 hr rate or about 16.5 kWh.

It has been remarkably resilient.  It was poisoned in it's 2nd year. I worked security where I lived, and had a cells go very dark and murky. It remained testing as one of the better cells for a couple years, but adventually became clearer and I suppose what ever someone stuck in the cell became adhered to the plates. It was still coming up to a high SG until a couple years ago. Now is just a dead cell, so I'm not charging correctly for 11 cells, when the sun goes down it's basically passing through so voltage goes to about 23.8-24 volts.

The battery it's self has surprising amount of capacity! Went 5 days with very little charging this winter and it kept the 20 year old fridge and lights computer running. I'll swap it out in the next year, if I knew how resilient it was going to be I'd have replaced the cell 3-4 years ago, likely $6-700 today. Runs on my Prosine and Magnum inverters but the Exeltech doesn't handle the low voltage well.

NAWS use to sell Crown forklift batteries, said it wasn't uncommon for them to last 20+ years. They do require a bit more maintenance and marginally more distilled water. I was using 4-6 gallons a year, but since the cell is gone, I'm basically over charging the remaining cells(IMHO) and use a gallon every couple weeks. Equalizing every month.