Battery question

[joshnz]

On a solar site we have two 12V 200Ah Sla battery's in series.
We have two 24v solar panels rated at 190 Watts each in parallel.

Here are the questions
1. Minimum Voltage , I think it will be 22 volts.
2. With these panels and battery's I think it will take 22 Hours to fully charge.


200Ah + 10% / 10Ah is this correct?

[budm]

Re: Battery question

To charge 12V batteries, the voltage source from charger needs to be around 13.75V, the voltage source cannot be lower than the batteries voltage.

http://batteryuniversity.com/learn/a...d_acid_battery

http://batteryuniversity.com/learn/a...ased_batteries

http://batteryuniversity.com/learn/a...ar_and_turbine

[Trick Fix]

Re: Battery question

@joshnz,Please,Slowly,
two 12V 200Ah Sla battery's in series is 24V 200Ah,--is Corect?
Ideal charge is 10% of capacity.
This means 20Amp --- 10% of maximum capacity.
Maximum Voltage during charging does not exceed
(for two 12V batteries connected in series) _______________max 28 V.
to charge will any practical good.

Beware the charging current to the batteries lasted longer,

Greetings,

[joshnz]

Re: Battery question

Oh i should have mentioned panel oc voltage is 45volts and have charge controller.
Panels provide 5 amps each at 35v

[Trick Fix]

Re: Battery question

As I understand it, you have the something like this schematic:

[Trick Fix]

Re: Battery question

Two 12v 200Ah ACU in series, to be charged with a 10% is
20 Amps for a period of 15h (to be 100% full).

+5h is "throwing" energy conversion power in Chemistry.(utilization factor)

If you are charged only with 10Amp, then time should be extended to 30h
to be charged to 100%.

Of course all this is true if the batteries were fully discharged.

Best Regards,

[joshnz]

Re: Battery question

As I understand it, you have the something like this schematic:

Exactly.
only thing is there is no diode to stop panel getting voltage from other panel.

battery voltage is currently at 24V

We may be going up there in the next two weeks to add third panel site is 940 meters above sea level takes some time to get up there.

[Trick Fix]

Re: Battery question

Good luck to you there!,

If you get stuck or something does not go right, pick up,
I heard all their knowledge and be able to activate to help you,

....everyone Welcome ! :-)

[joshnz]

Re: Battery question

Here are the voltage statistics.
18th of April

last 30 days

[joshnz]

Re: Battery question

On a solar site we have two 12V 200Ah Sla battery's in series.
We have two 24v solar panels rated at 190 Watts each in parallel.

Here are the questions
1. Minimum Discharge Voltage , I think it will be 22 volts.
2. With these panels, charge controller, battery's I think it will take 22 Hours to fully charge.


200Ah battery capacity + 10% for charge losses / 10 Amp charge current

we are taking around 1 amp 24/7.

[Trick Fix]

Re: Battery question

SORRY - You're not just insane! :-)
Who else is so perfectionist analyze the battery voltage?
This is unprecedented! -----Perfekné!

I can not believe that someone so much invested in this scenario,

In any case, I admire Enerjiji that you invest in this all,,,

I enjoy it, as there are such exibiconisti,
:-)

[redwire]

Re: Battery question

I have used these graphs before. For the time since April 6, battery about 12.5V down to 12.0V which means the system is not doing well.
I would say your battery is too small. Voltage comes up quick in full sun, almost too fast. Lots of charging when sunny.
Look at the night-time voltages (dips). You can tell how heavy the load is by looking at the slope of the night-time portion. It's quite steep, meaning the load is too high for the battery size. That would be my guess.

[kc8adu]

Re: Battery question

or they are already badly sulphated.
voltage setpoint may be too low.
i would CAREFULLY equalise them.like 15v at low current 24h and watch the temp.

[joshnz]

Re: Battery question

Charge controller holds them at 27 volts and is meant to equaize them with a 30v boost before float charge

[joshnz]

Re: Battery question

1 amp out of 200 is small in my opinion

[redwire]

Re: Battery question

jopshnz, I designed remote-site solar systems that failed and I had to helicopter in at $1,000/hr, land in muskeg and fix them. It's no fun. Important to really look at the data and have the right parts when you go in...
What I will talk about is based on rough % state-of-charge verse battery voltage. Attached is a graph, it might be slightly off from your SLA but shows my viewpoint. Assuming around 20C temp.

When the system was doing well in March, daytime charging peaks are 27.5V which is great (100% charged), and night-time dips 25.4V falling to 24.8V so I estimate the pack is down to 70% by sunrise.
Some rough math: 14hrs of darkness, 30% of 200Ah is 60Ah (consumed) gives about a 4.3A load.
At this point, I would suspect
- You have night-time parasitic current drain, backfeed to the solar arrays or the charge controller (I hope it's not a Morningstar), or your load is simply drawing more current than expected.
- The battery is failing and is no where near 200Ah capacity, like kc8adu says, it could be sulphated.

In sunlight, the battery voltage (after April 13) 24.5V jumps up to 26.0V, saying 55% capacity at sunrise and 100% charged an hour or two later. This recovery is too quick and indicative of a battery problem. In full sun your panels put out 10A total?

I think the battery is performing poorly and adding another panel would not help.
It's also important the data acquisition system is properly grounded (single point), so the readings are accurate. Charging current can artificially inflate the charge voltage numbers if the grounding is wrong.

[joshnz]

Re: Battery question

Average temp will be 10 deg c.
will get snow in next few months.

[joshnz]

Re: Battery question

We have 3x 6.5 Watts
And one 2.5 Watt device.

i have uploaded a layout of the site.
Poe router is data recorder.

also uploaded chart from today.

[redwire]

Re: Battery question

From the graph, it looks like the system can handle poor sun/cloud for about 5-7 days before the batteries get low, and about the same time to recover.

I just the feel the battery is working too hard. Either the load is higher than expected or the battery capacity is smaller than expected.

The RB750UP router is rated for 2.4-3.6W, and I'm not sure about the AP and bridge models but 24W total seems reasonable.

More stuff to check:
I would ensure both batteries are very similar (model, age) and were equalized before being put into service. One might be doing most of the work. Yes the charger is daily equalizing "the 24V pack"- overcharging one while the other is still undercharged. Are they Powerstar? 200Ah is a 130lb beast, huge.

The charge-controller temperature sensor.
I ended up putting batteries on styrofoam to insulate them from the metal enclosure. Daytime sunlight would heat up the cabinet and the charge-controller would backoff charge voltage but the batteries were still cold.
Is the charge controller set up for gel-cell or flooded types? What make is it.

[joshnz]

Re: Battery question

Charge controller
EP Tracer 2210RN

Batterys are same make model should be same age, yes very heavy hurt my injured shoulder moving them from trailer to site 30 meters away.

Don't know the brand of the batterys i would have to ask.

Owner asked me if we should goto 260ah.

Also there a camera rated at 3 watts,