New Rolls Surrette l16's Not holding charge

Sdavison

I feel like I'm going crazy! I have a 24volt outback 3500 system that is charged by PV. today I finally upgraded from t105 batteries to rolls Surrette l16's (455amp I believe)

They got a full cycle today 4 hour absorb and 1 hour float cycle. The moment the sun went down and with very little load they just started dropping in voltage.

I could use help please. This makes no sense!

Scott

Vic

Hi Scott,  Welcome to the Forum.

The following  Link is for the Surrette Battery Manual:

https://www.rollsbattery.com/wp-content/uploads/2018/01/Rolls_Battery_Manual.pdf

Page 9 describes how to place a new battery bank into service.

Assuming that your new batteries are Flooded Lead Acid (FLA) batteries,   you should follow those instructions and charge settings.

In the past,  Surrette suggested a Commissioning Charge and EQ for a new bank.

What voltage did you use for Absorb. 

Also assume that these are NEW batteries (?).

Later,   thanks for any additional info,    Vic

BB.

Welcome to the forum Scott,

I think these are your batteries:

https://www.solar-electric.com/rolls-surrette-s6-l16-hc-deep-cycle-battery.html

4x 6 volt batteries in series? Any Parallel strings?

Details matter here... What are the charging settings (absorb voltage setpoint, float set point)?

When you had them on 4 hours of absorb, did you take a voltage reading on the battery bus?

Have you compared your settings to the Rolls manual?

https://www.solar-electric.com/lib/wind-sun/surrette-manual.pdf

Rolls tends to specify higher charging voltages for their flooded cell batteries (~30.00 volts @ room temperature, vs 59.50 volts for other brands of FLA batteries).

Do you have a hydrometer? Have you measured and logged all of the cells (as received, when "Full", after corrective Equalization Charge--If needed)?

https://www.solar-electric.com/search/?q=hydrometer

At the end of the absorb cycle (4 hours), what was the charging voltage/current? (End amps from Rolls is around 2-3% of battery bank 20 Hour AH capacity--i.e., 100 AH = 2-3 amps rate of charge near end of absorb cycle)

What is the battery bank voltage when you are "concerned"... Around 25.4 to 25.8 volts is usually "full charge" for a resting FLA battery bank (vs ~29-30 volts when charging and 27.00 volts "float").

Where (roughly--Nearest larger city) is the system installed?

What size solar array do you have (3,500 Watts)?

On a cool/clear spring/fall day, your system would output a typical (best case maximum--a few days a year) around:

• 3,500 Watts * 0.77 panel+controller derating * 1/30.00 volts absorb charging = ~90 Amps

And the typical Outback FM80 Controller, would be limited to 80 amps maximum (it is normal to "over panel" an MPPT charge controller to allow for hot panels with reduced Vmp-array/Pmp-array).

Anyway--More questions than answers at this point.

-Bill

mcgivor

Sdavison said:

I feel like I'm going crazy! I have a 24volt outback 3500 system that is charged by PV. today I finally upgraded from t105 batteries to rolls Surrette l16's (455amp I believe)

They got a full cycle today 4 hour absorb and 1 hour float cycle. The moment the sun went down and with very little load they just started dropping in voltage.

I could use help please. This makes no sense!

Scott

The key question is what voltages are you reading, it would be normal to see a rapid drop from ~27.2V float to ~25.6V  without any loads  as soon as the array is not capable of passing current to the battery,, any loads wI'll increase the drop.

Sdavison

Y'all are amazing. Just read the manual five times and reset all the parameters on the mate controller.

There was no way the batteries got 10 hours on an absorb cycle to get started.

I'm actually going to run a 10 hour cycle tonight with the generator and check it with hydrometer in the morning.

I'll update you on the progress. Amazing knowledge on this forum.

Thanks