Battery bank low capacity, 2 month of use

[Venezuela Solar]

Hi everyone, this is a favor for a friend who is initiating in the bussines of solar energy, he recently installed a system with the following specifications:

(1) Inverter-charger 6000w rated capacity 8000w peak
(8) 150ah 12v sealed lead acid batteries (gel)
48v, 4S 2P arrangement
2400w solar arrangement (8 modules of 300w) 4S 2P 50 voc
Charge controller double solar entry one for each series of panel (dont have the specs, but it can handle the solar arrangement)

Recently the batteries started to fail, the hole bank, during day time you can use almost everything like normal, on night time the batteries only last 40-50 minutes, we have checked 4 of 8 batteries with a 12v charger (asuming there was a problem with the charge controller or the inverter) and a 12v inverter with a load of 130w (two incandescent bulbs) and i have measure the Whs with a Wh meter (with a coil) and with a kil-a-watt meter (both on the AC side, we dont have any Dc meter for wh or amps yet) and the results are a range from 44wh to 60wh per battery (yes wh, not even a Kwh) charging voltage rises in about 30 min with 5 amps, resting voltage is at 13-13.2 on each battery studied, i would like to know your opinion on the subject, i think i can declare the batteries dead with no solution right?

Extra info:
Both the inverter and the charge controller look to be working fine, at least the voltage rise acordenly to the batteries voltage and on day time there is no problem using appliences

All equiment its chinese, branded Efrenar (spanish brand, but its chinese)

Only two month of use

I havent see any mistakes on the installer part (wires, sizes, conections)

Thanks a lot before hand

 

[gnubie]

Can you clarify the arrangement of the panels regarding VoC, ie what voltage is your overall solar array producing?

While it's not impossible (there are boost chargers out there) 50Voc (with a correspondingly lower Vmp) makes it challenging to charge a 48V battery. MPPT charge controllers want a fair bit of headroom to play with, Victron needs 5V > battery to commence charging and 1V > battery to continue charging; others need 2V > battery to continue charging.

 

[Supervstech]

What voltage exactly are the batteries rest voltage when you ran the kilowatt meter?

 

[Supervstech]

13.2 even is not a fully charged sla...

It needs to hit 14.4 really.
Does the charger you used have a sla setting? If you are only hitting 13.2v, the cells wont get fully charged.

 

[Ped]

57.6v must be hit everyday and held there until amperage drops below .5% of bank capacity.

 

[Venezuela Solar]

Can you clarify the arrangement of the panels regarding VoC, ie what voltage is your overall solar array producing?

While it's not impossible (there are boost chargers out there) 50Voc (with a correspondingly lower Vmp) makes it challenging to charge a 48V battery. MPPT charge controllers want a fair bit of headroom to play with, Victron needs 5V > battery to commence charging and 1V > battery to continue charging; others need 2V > battery to continue charging.

Sorry, the VOC of each module is 37v and the arrangement its two rows in series (4S each) and the controller have 2 different entries for each row, the overall voltege its around 148voc

 

[SCClockDr]

1. Where on the planet is this installation?
2. Need to employ a 1-1.2Kw load on each solar SCC's output during peak period to confirm they are producing the specified wattage.
3. What is the average daily consumption from grid records for the months you mentioned?
   1. During the months solar was available?
   2. During 1, 2, or 3 years for the same months?
4. 150ah X 2 = 300 / 2 (for being LA)= 150ah total.
   1. 150 X 48 = 7.2KWa total battery capacity from 100% > 50% SOC
   2. 1:15 duration @ 6Kw demand.
   3. 15-20 hours to recharge to 100% SOC
      1. Sealed lead acid can't be pushed to avoid gassing.

My initial assessment with some assumptions would be:

1. Insufficient battery capacity to fulfill the demanded consumption.
2. Insufficient charge time to bring the batteries back to 100% SOC.
3. Possible over voltage during the charge cycle causing out gassing.

 

[Steve_S]

Can't find any information whatsoever on "Efrenar" brand / label. If there is a link or something like a pdf manual, it would be helpful for the Solar Charge Controller. Being that Venezuela Solar is located in Maracaibo, Venezuela (per their user profile) I think solar access is pretty good provided no trees to block it ;-) In some ways, this is simpler to help because they use the same power standards are north America I believe.

Is the Solar Controller capable of putting out the required volts & amps to properly charge the batteries is my 1st question ?
Second Question is exactly how much is needed for (8) 150ah 12v SLA batteries in a 48v, 4S 2P arrangement ?

2.4 kw of panel setup as 4s2p should be delivering at least 2kw average +/- a bit and 120VDC on average, which should do it but "just" being that the batteries are SLA. It certainly would not hurt to add more panels, even 600W would help makeup for poor production days (overcast/cloudy etc)

 

[Venezuela Solar]

What voltage exactly are the batteries rest voltage when you ran the kilowatt meter?

The resting voltage its at 13.2 after 24h, i left the batteries charging for 12 hours with 2-4 amps when i disconnect the batteries i goes to 13-13.2, this is after charging it with another inverter-charger with 10 amps, when the inverter says its full (30 minutes to full charge ) i plug it to the other charger

 

[Ped]

I thought they were 48v?

 

[SCClockDr]

2.4 kw of panel setup as 4s2p should be delivering at least 2kw average +/- a bit and 120VDC on average, which should do it but "just" being that the batteries are SLA. It certainly would not hurt to add more panels, even 600W would help makeup for poor production days (overcast/cloudy etc)

I'd just add one of the limiting factors with any LA battery is the 80-100% portion of the charge profile. More energy will not yield faster charging due to chemistry.
Without knowing the demand it is a crapshoot re recommendations. A 6Kw inverter is huge vs 7.2KWa of storage & 2.4Kw of solar.

 

[Supervstech]

I thought they were 48v?

The bank of 4 is 48v, but he is individually checking and charging the batteries to eliminate causes.

 

[SCClockDr]

I thought they were 48v?

48V built from 12V jars.

 

[SCClockDr]

@Venezuela Solar, do you have any grid usage data?

 

[Venezuela Solar]

1. Where on the planet is this installation?
2. Need to employ a 1-1.2Kw load on each solar SCC's output during peak period to confirm they are producing the specified wattage.
3. What is the average daily consumption from grid records for the months you mentioned?
   1. During the months solar was available?
   2. During 1, 2, or 3 years for the same months?
4. 150ah X 2 = 300 / 2 (for being LA)= 150ah total.
   1. 150 X 48 = 7.2KWa total battery capacity from 100% > 50% SOC
   2. 1:15 duration @ 6Kw demand.
   3. 15-20 hours to recharge to 100% SOC
      1. Sealed lead acid can't be pushed to avoid gassing.

My initial assessment with some assumptions would be:

1. Insufficient battery capacity to fulfill the demanded consumption.
2. Insufficient charge time to bring the batteries back to 100% SOC.
3. Possible over voltage during the charge cycle causing out gassing.

1) Location: Maracaibo, Venezuela really good sunny days, sun peak its about 1-2 pm, good production at 9 am even at 5-6 pm

2) Will do this test

3) My country its currently a chaos, there is no record from the energy company and my friend didnt track record of it, the continuos load expected its about 4000w, two 12.000btu air conditioner (110v), led lights, one fridge, once in a while a mocrowave

Thanks for the assessment, i believe its insuficient battery bank or one battery deffective damage the hole system

 

[SCClockDr]

Thanks for the response.
If possible, procure a grid style meter from scrap & get it installed. With pencil & paper record daily numbers from the grid & inverter. In your situation conservation is paramount I'd assume to preserve resources for food & meds. Will pray for you, your loved ones, & friend.

 

[SolarRat]

Gel batteries are very "fragile". They don't handle high draws or high charge currents well, and any off-gassing can't be replaced like it can in a FLA (the only LA's I'd use in a high demand bank).

If you can accurately weigh a brand new battery of the same make, and then weigh yours, you might find yours weigh many grams less from excessive off-gassing.

 

[Bigbillsd]

Are you able to measure the amps going into the batteries during the daytime? Do you have a web link for the controllers so we can look at the specifications? When I googled that brand of controller I found nothing. -Bill

 

[SolarRat]

the continuos load expected its about 4000w, two 12.000btu air conditioner (110v), led lights, one fridge, once in a while a mocrowave

The 48v 300ah 14.4kwh battery bank has about 7.2kwh usable. That will last less than two hours at your continuous load. How low have these batteries been taken? Were they often drained to the point of the inverter kicking off? If so, that would kill them fast.

 

[Bigbillsd]

Oh my, how did i miss the Air Conditioner comments. You need a lot more batteries! You have less than 2 hours of power @ 4000 watt draw.