Charge Controller

[Naeem]

Dear Guys,

I have installed off-Grid system of 3KWp (300 Wp module each) and 4 batteries (GEL 12V, 100A.h) with morning star controller (Tri-Star 60A).

first time the controller failed ( FET transistor failure ), this lead to heat in batteries and bad smell goes out from them. after that I have re-install a new controller with the same specifications, after some time the same bad smell goes out and the controller suffered from the same problem.

So the question is that can the batteries (if it is destroyed) affect the controller and ruin it.

 

[GoldDigger]

Dear Guys,

I have installed off-Grid system of 3KWp (300 Wp module each) and 4 batteries (GEL 12V, 100A.h) with morning star controller (Tri-Star 60A).

first time the controller failed ( FET transistor failure ), this lead to heat in batteries and bad smell goes out from them. after that I have re-install a new controller with the same specifications, after some time the same bad smell goes out and the controller suffered from the same problem.

So the question is that can the batteries (if it is destroyed) affect the controller and ruin it.

Naeem,
You may have a badly designed system.
1. One 300w panel does not make a 3kWh system, since no place on earth has ten solar hours per day (equivalent of ten hours of full noon sun)
2. GEL batteries are not suitable for solar applications as they cannot safely be charged at higher than a C/20 rate. Your 300W panel with an MPPT controller could produce C/12.
3. Once you have caused a sealed cell to vent heavily it is ruined and should be replaced. GEL cells can be permanently damaged by overcharge even if they do not vent.
4. I do not see a good explanation for your CC failing because of damage to the battery. Is the temperature too high?

 

[BillK-AZ]

You do not state the nominal system DC voltage, it could be 12, 24, or 48 volts with four batteries. I assume you have the batteries in series for 48 volts. Full sun would give you 60A for charging a 100AH battery bank. Not a good design, consult your battery supplier to determine a recommended charging current.

In any event, if you have a 3,000 peak watt PV array, and batteries with about 4.8 KWH total capacity, you have a very excessive array to battery ratio. With this situation, battery life will be very short.

With a good charge controller that limits the charging voltage to the proper value for the battery temperature, the battery should only accept a suitable charge current. Kind of like automotive systems that can have 125A alternators, but with limited output voltage.

If batteries are over-charged and hot, they can go into a thermal runaway situation and destroy themselves. A Tri-Star controller should limit the charge current to its nominal in the usual situation of higher voltage PV arrays charging lower voltage batteries. If it is set for the wrong nominal output voltage, it can severely over-charge the battery bank, especially with such a high ratio of PV power to battery capacity.

You need to carefully monitor the battery voltage and charge current to be able to determine what is happening.

 

[Naeem]

Naeem,
You may have a badly designed system.
1. One 300w panel does not make a 3kWh system, since no place on earth has ten solar hours per day (equivalent of ten hours of full noon sun)
2. GEL batteries are not suitable for solar applications as they cannot safely be charged at higher than a C/20 rate. Your 300W panel with an MPPT controller could produce C/12.
3. Once you have caused a sealed cell to vent heavily it is ruined and should be replaced. GEL cells can be permanently damaged by overcharge even if they do not vent.
4. I do not see a good explanation for your CC failing because of damage to the battery. Is the temperature too high?

1. the system size is 3KWp means 10 panels of 300Wp modules.

2. Gel batteries as common know is sensitive to overcharging but better for temperature reaction, I have used Gel batteries more than once, but this is the first time I suffer from matter like this.

3. I think it should be replaced agree with you.

4. As I know the batteries can't destroy the CC but the CC can destroy the batteries by causing overcharging if any failure happens. So this is what I am searching for.

 

[Naeem]

You do not state the nominal system DC voltage, it could be 12, 24, or 48 volts with four batteries. I assume you have the batteries in series for 48 volts. Full sun would give you 60A for charging a 100AH battery bank. Not a good design, consult your battery supplier to determine a recommended charging current.

In any event, if you have a 3,000 peak watt PV array, and batteries with about 4.8 KWH total capacity, you have a very excessive array to battery ratio. With this situation, battery life will be very short.

With a good charge controller that limits the charging voltage to the proper value for the battery temperature, the battery should only accept a suitable charge current. Kind of like automotive systems that can have 125A alternators, but with limited output voltage.

If batteries are over-charged and hot, they can go into a thermal runaway situation and destroy themselves. A Tri-Star controller should limit the charge current to its nominal in the usual situation of higher voltage PV arrays charging lower voltage batteries. If it is set for the wrong nominal output voltage, it can severely over-charge the battery bank, especially with such a high ratio of PV power to battery capacity.

You need to carefully monitor the battery voltage and charge current to be able to determine what is happening.

yes this system is configured for 48V system (4 batteries in series).

To be more precise, this system is sub-system into other 3 systems, all systems have the same configuration, but this is the only one has this problem.

I have agreed with you that the size of P.V is much more than the battery bank, but this is not a reason to destroy batteries or charge controller

 

[GoldDigger]

yes this system is configured for 48V system (4 batteries in series).

To be more precise, this system is sub-system into other 3 systems, all systems have the same configuration, but this is the only one has this problem.

I have agreed with you that the size of P.V is much more than the battery bank, but this is not a reason to destroy batteries or charge controller

Is that Morning Star CC a PMW or MPPT type? I know that Morning Star makes both.

If it is a PWM CC, then overpaneling can indeed cause the CC to fail. Possibly the system in question has lower wiring resistance or more favorable panel angles compared to the others and so is producing a higher instantaneous current at the CC input.

Do you know what part of the CC is failing? If it is the input stage transistors of an MPPT CC or the pass elements of a PWM CC, then it suggests overcurrent as the cause.
If the battery side gets short circuited, it will draw more current from the panels (but only up to the difference between Imp and Isc), but will also probably cause either type of CC to shut down completely on undervoltage.
For a 48V system, I do think that it is most likely that you are using an MPPT CC. How are your ten panels wired? Five strings of two or two strings of five?