Battery bank - wired correctly?

Ecobabe

Hi all

I have just started living off-grid and have had some problems with my power supply. If I do not turn a lot of lights and appliances on in the morning on a sunny day the power usually shuts off to the house. I cannot reset it, it will only turn itself on again when the sun sets. Another problem is when I use a single light at night the power flashes and I need to turn on more lights to keep the current steady.

I have uploaded a drawing of my batteries - are they wired correctly? I have no idea about these things but have been trying to research and feel a bit confused about series/parallel wiring. The batteries are 8 by 6 volt 225amp at 20hr. How many volts and amps is my setup?

Cariboocoot

Re: Battery bank - wired correctly?

Welcome to the forum.

What is the system Voltage supposed to be?

With eight 6 Volt batteries you could have:
12 Volts with four parallel strings
24 Volts with two parallel strings
48 Volts with one single string

The drawing looks sort of like 24 Volts with two parallel strings.
Look at method #2 on this page: http://www.smartgauge.co.uk/batt_con.html

Only instead of single batteries you have a string of four, and instead of four in parallel you have only two. The important bit is to draw the positive from one string and the negative from the other to try and keep current even between the two strings.

Blackcherry04

Re: Battery bank - wired correctly?

Yep, 2 strings of 24 Volts @ 220 x 2= 440 amp hrs. Sounds like your Inverter is going into standby and getting stuck and causing the flicker. You might to be able to lower the standby watts or shut it off by setting it at 0 watts. It may have a UPS mode that will shut it off. I last option would to keep a load on it to keep it pulled in. What kind of Inverter is it ??

NorthGuy

Re: Battery bank - wired correctly?

It would be good to know what is the inverter and if it displays some sort of errors when it shuts down. Could be a problem with inverter (or its settings).

This also could be because there's simply not enough power. Adding a generator to your system will help to avoid these problems.

halfcrazy

Re: Battery bank - wired correctly?

My guess is that the inverter is unhappy during the sunny time. Maybe the charge controller is charging to high and the inverter is shutting down on High DC voltage. Now at nite the blinking lights is do to Search mode. Most inverters have search mode and it will pulse waiting for a load to turn on. Some lights can be to small to bring the inverter out of search. Search is usually adjustable.

What inverter do you have? What charge controller do you have?

My main concern is that you "May" be over charging the batteries. I would first verify the battery manufacturer and then find out from them what to Bulk charge, Float charge and Equalize charge voltage are. Then call the Charge controller manufacturer for help verifying those numbers. Then move on to the Inverter

Ryan

Ecobabe

Re: Battery bank - wired correctly?

Blackcherry04 wrote: »

Yep, 2 strings of 24 Volts @ 220 x 2= 440 amp hrs. Sounds like your Inverter is going into standby and getting stuck and causing the flicker. You might to be able to lower the standby watts or shut it off by setting it at 0 watts. It may have a UPS mode that will shut it off. I last option would to keep a load on it to keep it pulled in. What kind of Inverter is it ??

Hi all,

Thank you so much for your replies, this is all very new to me.

The inverter is Selectronic Sine Wave Inverter SE12 24volt, 700 watt continuous; 2000 watt surge. I will try to add a photo

NorthGuy

Re: Battery bank - wired correctly?

Ecobabe wrote: »

The inverter is Selectronic Sine Wave Inverter SE12 24volt, 700 watt continuous; 2000 watt surge. I will try to add a photo

Very good photo, except it is turned 90 degrees.

There are several indicator LED lights on the left side (bottom on the picture). When the power goes off next time, look at these lights and record which ones are on, which ones are off, and which ones are flashing.

Ecobabe

Re: Battery bank - wired correctly?

halfcrazy wrote: »

My guess is that the inverter is unhappy during the sunny time. Maybe the charge controller is charging to high and the inverter is shutting down on High DC voltage. Now at nite the blinking lights is do to Search mode. Most inverters have search mode and it will pulse waiting for a load to turn on. Some lights can be to small to bring the inverter out of search. Search is usually adjustable.

What inverter do you have? What charge controller do you have?

My main concern is that you "May" be over charging the batteries. I would first verify the battery manufacturer and then find out from them what to Bulk charge, Float charge and Equalize charge voltage are. Then call the Charge controller manufacturer for help verifying those numbers. Then move on to the Inverter

Ryan

Hi Ryan

The charge controller is Plasmatronics PL20 N1271. I downloaded a user manual from the Internet, it seems to have a lot if adjustable settings but with only one button it is not the most user friendly device for a novice. I will try to add a photo. BTW, the Inverter doesn't appear to have adjustable settings.

Thanks,
Amy

Cariboocoot

Re: Battery bank - wired correctly?

Oh goody: 230 VAC 50 Hz power.

So if the battery configuration is as evaluated there should be no trouble keeping up with 700 Watts of output (about 30 Amps on the DC side).

Note that this inverter does have some status lights: are any of them indicating a fault when it acts up?
(AC overload, DC low Voltage, Temperature overload)

And of course we're going to want to know what is being used to charge the batteries.

Cariboocoot

Re: Battery bank - wired correctly?

That's an odd charge controller too. Appears to be "positive ground" with only one (+) terminal and separate (-) terminals for PV, Batt, and Load.

What it's showing on the readout doesn't make much sense either.

Why do I have the horrible feeling that the solution here is going to be "replace the equipment with better quality stuff"? :roll:

Blackcherry04

Re: Battery bank - wired correctly?

From you Inverter Manual Page 11 & 12. Here is how you adjust the Search. What HC said about the High Voltage, that you'll have to set on the Charge Controller

Auto Start Adjust LED (6) (red) Flashing
It is sometimes necessary to adjust the auto start sensitivity to overcome
what is called “Phantom Loads”. A phantom load is a load that tricks the
inverter into thinking it should be ON instead of in SLEEP mode.
The wiring of a house or a portable stereo system in standby are good
examples of a phantom load. These loads serve no purpose but yet can
increase battery drain by bringing the inverter ON. Hold the Mode button (7)
down until LED (6) begins to flash, (approximately 1 second) indicating you
are ready to adjust this setting. The SE12 will leave the factory with a setting
of 4 watts. Now press the Mode button (7) until the desired value is sought.
LEDs (1) – (4) will return to either Status or Voltmeter after 20 seconds.

LED (1) ON....16 watts
LED (2) ON....12 watts
LED (3) ON....8 watts
LED (4) ON....4 watts
ALL LEDs ON

Inverter will remain ON at all times. This could
be used if a fax machine or VCR is required to
stay on at all times. Be aware that this will use
more power from your battery.


Inverter shuts down during the middle of the day, and comes
back ON late in the afternoon

This is more than likely caused by high battery volts during peak charging
times from Solar Panels. Battery volts should never exceed 34 volts. If this is
the case, have your Solar Regulator checked.
.

Ecobabe

Re: Battery bank - wired correctly?

I have 8 panels on the roof, no idea how much power they produce. I do not have any paperwork for the system. Do I have to get on the roof and try to find labels on the panels? Or is there an easier way to find out?

When the power cuts out during the day I don't notice any of the warning lights on the inverter. Powering off and on does not help. I have suspected it may be the controller causing the cut out but it is only a guess

Cariboocoot

Re: Battery bank - wired correctly?

I hate to say it but you are going to need that panel info. It's a little hard to understand your system unless you know what it's made of, and if you don't understand it you'll just get one problem after another. Can you count the cells on them? They should be visible as individual dark shapes on the panel surface (sometimes it's hard to tell).

It is possible that the controller is allowing the battery Voltage to go "too high" as far as the inverter is concerned, causing it to shut down. This could be a problem with the controller, or a need for reprogramming it, or an incompatibility between the two (inverter unable to take high charging Voltages).

This also means you should get a digital multimeter and learn how to use it so that you can at least measure Voltage and know if it is high/low at any given point in the system. It would be a good idea to have a hydrometer to check the batteries' specific gravity with as well, and make sure the fluid level is at the right height.

NorthGuy

Re: Battery bank - wired correctly?

Ecobabe wrote: »

When the power cuts out during the day I don't notice any of the warning lights on the inverter. Powering off and on does not help. I have suspected it may be the controller causing the cut out but it is only a guess

The inverter may shut down because it is overloaded/overheated or because the battery voltage is bad or because the inverter is bad.

To see if the inverter is overheated, you can simply touch it and see if it's hot or not.

You can also measure battery voltage with a multimeter. Buy a multimeter, learn how to measure "DC Voltage" with it, then, once the inverter shuts down, measure on battery terminals where wires are going to the inverter - one lead to one terminal and the other lead to other terminal. Tell us the number.

westbranch

Re: Battery bank - wired correctly?

To add to North guy's comment, you should measure the voltage of all the batteries and post them as well as the total measured at the 'departure point' of the battery cables from the battery bank. Variation between the small batteries can also tell us something.
Resting voltage is best measured 3 hours or more after charging has finished.

hope this helps.

Ecobabe

Re: Battery bank - wired correctly?

I borrowed a ladder and checked the panels on the roof - a little bit scary lol.

The panels are 8 x 80watt, 1.5 cell each

BB.

Re: Battery bank - wired correctly?

Not sure what the 1.5 cell means... Usually looking for Voc/Vmp/Isc/Imp type numbers (really need Vmp/Imp).

Vmp will be around ~18 volts for a 12 volt array. And around ~35-36 volts for a 24 volt array. For Grid Tied panels, you may see Vmp~30 volts or something else.

I would guess you have 80 watts panels with Vmp~17.5 volts with Imp~4.5 amps... Two in series for ~35 volt Vmp array. 4 parallel strings.

One good sunny day, you should see:

4.5 amps * 4 = ~18 amps peak (maybe a few amps less) on clear/sunny days around noon with batteries needing charging (and/or heavy load on batteries). If the batteries are near fully charged, you may see a lot less current.

Guesses....

-Bill