12v 95a/h lead acid batteries

Not commenting on what's going on, just making sure we're all "singing from the same song-sheet".

As I understand it, you have:

... with 1- connected to 2+, and 24V out taken from 1+ and 2-. Is this correct?

[BTW, you said "by connecting 6 in series side by side ..." . If my understanding is correct, that should've read "by connecting 6 in parallel side by side ..." ]

Hi Vinc,

Congratulation on your efforts to use a solar photovoltaic system.

About the batteries. You did connect them OK, but let me repeat it:

12 batteries, divided in two groups. Batteries 1 to 6 have negative poles connected together, as well as positive poles (that's parallel connection). This is Bank 1, an equivalent battery with 12 V voltage but with more that 550Ah capacity. Batteries 7 to 12 are connected like in Bank 1 , giving you the Bank 2.

Now connect the two banks in series, the positive of Bank 1 to the negative of Bank 2. The equivalent battery (let's call it BAT), is a 24 V / 550 Ah battery, having the negative pole to the negative pole of Bank 1 and the positive pole to the positive pole of Bank 2. You don't touch the connection between Bank 1 and Bank 2. BTW, all the wires connecting the parallel and serial configurations have to be thick, with good electrical connection to the batteries poles.

BAT has to be charged from your solar panel. This one has to provide a voltage larger than 24 V and the adequate current in order to charge BAT. It is good if the solar panel gives you 28V with some 21 A capability. In an ideal world, bringing this to BAT should charge it during the sun exposure (say about 8 hours) and this charge would be sufficient for your daily load.

But I think that your batteries (each 12v/95Ah) are unevenly charged.

This is the problem that you have to solve.

Now, I am just speculating: For the charging part, it is better to have your 12 batteries a bit different connected. Six groups of 24V/95Ah. (you make such a group connecting in series two 12V/95Ah batteries). Then this six groups will be connected parallel. So you have, again your BAT, but differently "internally" connected. Your problem is not over, yet, but using resistors, you can control a little bit better the individual charging current. Of coarse, all these can be avoided with a good charging device between the solar panel and the BAT (or batteries).

Hope that helps you, and please, let me know how it goes, I am interested (where is your house?).

Are your panels charging 24VDC? Or they are charging individual banks of 12 VDC? If so, it could be an unbalance in the charge. Maybe the addition of some diodes to make sure all batteries banks are receiving power in the right way. I agree with connecting the batteries two by two. It would make easier to check a defective battery too. Keep us informed. Nice to hear you are using this system. How about the price and return you are observing?

Your 6 batteries in a bank are connected in parallel, not series. Bank one and bank two are then connected in series to give you 24 V.

A potential problem with 6 batteries in parallel is that if one of those 6 batteries goes bad, it will cause the other 5 to discharge quickly as they try to charge the bad battery.

What is the voltage output of your solar cells? If it is 24 volts, then the solar cell output would be connected to the same terminals used for your inverter. You'd need diodes and a charge regulator. I didn't follow what you wrote in 3/. If you are connecting the solar output to just one bank of your two banks, the the other bank will not charge.

Within a single bank, it doesn't matter where you connect a 12 V charger: any positive terminal and any negative terminal will work. However, ordinarily, you would want to consider the two banks (once connected -1 to +2 per John's diagram) as a single very large 24 volt battery, and do any charging at 24 volts using the terminals +1 and -2.

Your battery bank is storing 13600Wh but you only charge about 3000Wh per day. It sound to me that you are over discharging the batteries. Check the electrolite levels with a hydrometer, it should be 1260, if not follow the instructions on how to recover the batteries. It might ne nessesary to force charge them from another source.

Christo

Checking battery volatges with a good voltmeter will show the state of the charge (assuming all batteries are of the same make and type).....

There are battery websites that will tell you what voltage is equal to what level of charge....

I also feel that your charging is at fault......

Also, next time, please post a circuit diagram yourself, it will save us guessing! as your description was so wrong it would not work at all!!

This is just speculation on my part but it might be a good idea to track the output voltage of your solar array through out the day. I suspect that you will find that the voltage from the solar array is insufficient to charge both banks most of the day but sufficient to charge one bank during that part. Around noon though sufficient light shines to partially charge both banks. To solve this you may need a more clever charge circuitry design (switching supply?) to more evenly distribute your converted solar energy.

Hi,

Boss, congrats for helping mother nature.

Please post a PHOTOGRAPH or connection diagram

Check your system as follows,

1. Hold Solar Panel one by one facing SUN and measure voltage... it should be 12 X 1.5 minimum at full SUN. If not check connections soldering clean ends of lugs.

2. Now check short circuit current with full SUNLIGHT. It should be within 10% of what is given on panel, say 1.5Amp min for 50 Watt.

3. f ALL ok you will get 2 X 12 X 1.5 = 36 V ..OK to charge 24 V battery

4 For 6p X 2s or 2s X6p battery bank with 95AH per battery you need total 24 X 50 Watt panels for normal discharge 10.5 v to full charge 14.2 v. Obviously you have 50% panels and you can discharge battery to 11.5 v that means inverter shall be set to cut off at 11.4 X 2 volts.

5. Solar panel works as a Power source with GOOD Sunlight, but it consumes power with NO/BAD light. You must have a DIODE or amanual disconnector or agood solar charge controller. CHECK it up.

6. Now Battery. Get only oen pair of battery mark 1A, 1B stickers. Connect 1A+ to Inv +, 1A- to 1B+, 1B- to Inv-. Sitch on, power on Inv from grid, chrge battery for min 18 hours with well ventilation or putting battery in water tub with water level habelow battery termilan. Make sure electrolyte level in all 6 X 2 cells is half inch above plates. If Inv is only inv use other charger OR with solar panels..2s X2p first day and 2s on second and third day.Use blocking diode REPEAT for all.

7 Ceck battery indidual cells , voltage shall be 2.0 to 2.2 v. If you observe any cell below 2.0 check density 1260 and consult nearest battery repairer.

8. Connect 2s X6p as it will require small size and length connections , wire size min 6 or max 10 mm sq.

9. With 12 X 50 X 3 to 5 Hr GOOD Sunlight you will get 1800 to 3000 Wh. Allow for losses in Electronics and Battery and u will get 1500 to 25oo Wh from Inverter. and your PC of 550 W say 500 W will work for 3 to 5 hours.

10. So, BOSS this is how , what you have, what you will get , if ALL IS OKAY.

11. Connect Inv and you should get 500 W load for 6 to 8 hours with good attempts

DONT EXPECT SMOOTH WORKING UNLESS YOU STUDY AND GET PROPER YHINGS.

My guess and suggetion to yor need are,

1. If you can ADD 12 X50W panels for full charge 10.2 to 14.v charge

2. wiyh 12 panels set Inv Low setting at 11.4v X 2, get Inv mfr help or use Digital Voltmeter 0 _ 30V and stop using when you reach 22.8 v

BEST LUCK. write to me your results or call for any more details. Once again Congratulations for use of RE Energy.

Sunny Regards.

Y.S.Kulkarni

Consultant, RE Project, INDIA +91-94 224 754 11

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