morning star ts60 mppt

We can try--What type of alarm are you getting? What is your system configuration (solar array size, series/parallel connected panels, battery bank voltage and Amp*Hour rating)? How are you using the system (emergency backup, daily cycling, etc.)? How is the battery bank (voltage, specific gravity, state of charge)?

If your batteries are discharged (below ~75% state of charge)--You need to get them recharged soon. Lead Acid batteries do not like to sit when discharged (and do not like deep discharging either).

Unfortunately, there is usually not very much that can be repaired in the field for the electronics. We did have one controller where the two-color LED fell out during shipment and it was put in "backwards"-- And green became red (controller was fine, just the LED colors where reversed).

I should also add--Check wiring and wiring connections. Loose/corroded/broken connections can cause faults too.

-Bill

If your alarm is at 21 volts (Battery Bus Voltage--And not MorningStar's alarm code #21)--Then your batteries are "dead" (or near dead). In general, older lead acid batteries that have been taken "dead" will fail in days to a couple of weeks (new is less than one year old, older is 3 years and older). The longer a battery bank sits (uncycled) below ~75% state of charge, the faster the bank will sulfate (and eventually, die).

Note: a 24 volt lead acid bank should not be taken below ~50% state of charge very often (longer cycle life) and never below ~20% state of charge (various reasons). Lead Acid battery bank voltages are not very accurate for estimating state of charge--But, roughly, (at room temperature) avoid taking your resting voltage much below ~24.0 volts (hours of 'resting'), and your under load voltage much below ~23.0 Volts (under normal loads--High surge current could take a partially discharged bank down to 21.0 volts for a few seconds).

So--Next question, why did the bank go to 21 volts? Was it too much load current*hours of discharge? Bad Weather? Too small of solar array/amount of sun for your loads? Failed solar panels/bad wiring connections/failed solar charge controller/failed battery bank?

At the very least, try to get your battery bank charged quickly (genset, utility power on AC battery charger). At a minimum of 5% to 10% (better) rate of charge. The longer they sit at "dead", the less likely you will be "lucky" to bring back your bank.

-Bill

Hmmm...

For most charge controllers, connect the battery bank first and the solar panels second.

If you do the opposite, it can confuse the charge controller.

-Bill