Need help understanding my BAE PVV 2v 1800ah Batteries

[Glenpk]

Hi Everyone,

My family and I are the proud new owners of an amazing property in the New England, NSW. It has been set up off grid and is somewhat of a dream come true.

Unfortunately I have minimal experience in off grid living and despite many hours of research remain quite bewildered. The basics:-

1) Batteries 24 x BAE PVV 2v 1800 -
2) Inverter Xantrex (now Schneider) - XW4548 -230-50
3) Panels Kyocera KD-135SX-1pu
4) Time in operation estimated 8-10years


I have a few questions which I hope the combined wisdom of the forum may answer:-

1) My batters have a c10 1440Ah and c100 1900Ah. On my inverter which figure to I enter?
2) I generally understand that in a 3 stage charging cycle I there is the bulk, absorption and then float. Can this happen from solar inversion or does it need a AC qualified load.
3) What should I set the bulk and absorption rate at - the date sheet suggest 2.33v o 2,4v which is 55.2V to 57.6 - I have set lower to avoid damage and hopefully trigger absorption without luck.
4) Float charge on the battery data sheet is is 2.25v - I believe I am safe with 54v?
4) Do I equalize GEL batteries - the battery manual suggests yes (which I guess would be right) but the manual suggests no. If yes the fact sheet suggests 2.33-2.4v which appears low noting its the same voltage as the bulk and absorption level.

General performance - so far the system is doing everything we want it to. However I am concern that the batteries are damaged (left to sit a few year before we bought the place.)

This week end past we hook a 1amp generator and ran it. Charge voltage now peaks at about 55.2V in the day - although by morning is about 49.6v.

From my reading I suspect that the batters have discharged and wondering if an equalisation might help?

Otherwise I am not sure how best assess the health of the batteries and how long they may be for the world.

Generally we run a fridge - freezer and a few appliances such that there is standby draw of 230w per hour. The regular cup of tea throughout the day. We use wood for heating and gas for cooking. There is a TV an associated comforts for night.

In short I believe the system we have is likely significantly larger than our needs and I am keen to out off the (inevitable) re-investment into new batteries as long as practical.

I say a thank you in advance to any thoughts

Yours

Glen

 

[sunshine_eggo]

1) Batteries 24 x BAE PVV 2v 1800 -
2) Inverter Xantrex (now Schneider) - XW4548 -230-50
3) Panels Kyocera KD-135SX-1pu
4) Time in operation estimated 8-10years

If #4 means you have old batteries.

1) My batters have a c10 1440Ah and c100 1900Ah. On my inverter which figure to I enter?

C10 means you can discharge 144A for 10 hours.
C100 means you can discharge 19A for 100 hours.

You're probably somewhere in between.

If they're 8-10 years old, I'd enter 1440Ah.

2) I generally understand that in a 3 stage charging cycle I there is the bulk, absorption and then float. Can this happen from solar inversion or does it need a AC qualified load.

I don't entirely understand the question. PV panels are usually connected to a solar charge controller (SCC) that charge the battery.

If you can link a manual for your hardware, I can probably come up with something better.

3) What should I set the bulk and absorption rate at - the date sheet suggest 2.33v o 2,4v which is 55.2V to 57.6 - I have set lower to avoid damage and hopefully trigger absorption without luck.

57.6V absorption. If you're not hitting absorption, you may not have sufficient charging capability.

4) Float charge on the battery data sheet is is 2.25v - I believe I am safe with 54v?

Good.

4) Do I equalize GEL batteries - the battery manual suggests yes (which I guess would be right) but the manual suggests no. If yes the fact sheet suggests 2.33-2.4v which appears low noting its the same voltage as the bulk and absorption level.

Never in the way that you would with flooded.

In this case, you might have your normal absorption charges to 2.33V/cell with an equalization run to 2.4V/cell every 30 days. Gels live longer with lower charge voltages. I would likely choose that scenario.

General performance - so far the system is doing everything we want it to. However I am concern that the batteries are damaged (left to sit a few year before we bought the place.)

That is almost certainly the case. Assuming an idealized loss of 2%/month, it likely dropped below a healthy voltage at about 6 months and began sustaining damage for the next 2.5 years. After 3 years, it's almost certain that it was notably below 50% charged.

A sustained equalization charge to 2.4V/cell would have been in order before reactivating the system.

This week end past we hook a 1amp generator and ran it. Charge voltage now peaks at about 55.2V in the day - although by morning is about 49.6v.

1A? 230VAC @ 1A = 230W? Can you clarify how many amps were going to the battery? A battery of that size should be charged with at least 70A, preferrably 2X that.

49.6V is not too bad. You're likely not discharging below 70-80% SoC based on the voltage. What you should do is:

1) When the battery is at peak voltage and charging, measure all 24 cells and confirm they are very nearly the same voltage.
2) repeat #1 first thing in the morning before any charging.

From my reading I suspect that the batters have discharged and wondering if an equalisation might help?

Regardless of performance, the 3 year sit demands an equalization charge. it should be done after the battery follows a normal bulk/absorption/float cycle.

Otherwise I am not sure how best assess the health of the batteries and how long they may be for the world.

It's very difficult to do without testing the capacity of the cells.

Generally we run a fridge - freezer and a few appliances such that there is standby draw of 230w per hour. The regular cup of tea throughout the day. We use wood for heating and gas for cooking. There is a TV an associated comforts for night.

In short I believe the system we have is likely significantly larger than our needs and I am keen to out off the (inevitable) re-investment into new batteries as long as practical.

For such a large bank, it appears you have relatively light loads.

Start loggin at least weekly performance data to establish trends. Morning charge voltage and temperature. If your system does not have a shunt that correctly displays % state of charge (your inverter might), then you can log reported SoC and low voltage. If you see that over time, the morning SoC is the same, but your voltage is inching lower over time, with no change in usage, that's a sign of degradation.

 

[Glenpk]

Dear Sunshine_eggo

Thank you for taking your time with such a thorough response. It really is appreciated.

This is the link to the inverter:

https://solar.se.com/us/wp-content/uploads/sites/7/2021/11/xw_hybrid_ic_install_guide_975-0384-01-02_rev-d_eng.pdf

My issue on the 3 stage cycle is that we don't seem to be able to go past the Bulk stage. The charge status is showing "Invert" but we were able to get to absorb (at least for a few minutes) with our little honda EU 10i Generator

https://cf.hondappsv.com/files/OM/OM000195GLOBAL/36ZT36310_Eng_print.pdf

I suspect the first thing to be doing is getting this evening and morning voltages checked - when you say very nearly do I look at 1 2 or 3 decimal places (2.2 to 2.3, 2.22 to 2.24, 2.222 to 2.224)?

Yours

Glen

 

[sunshine_eggo]

Do you have one of these circled items?



Voltages compared at 2.XX

 

[Glenpk]

So indeed,

It is a Xantrex MPPT 60-150

https://www.rpc.com.au/pdf/conext_MPPT_60_manual.pdf