Battery

[udect]

What is the good battery brand for solar panel. 12v battery.
Please help me to fin this, Because I try to make solar panel.
If you have eny link to boy it please sent me(ebay or...)

[Mike90250]

There are many deep cycle battery manufactuers. It's likely more important that you find a local vendor who carrys deep cycle or golf cart batteries, and use them for your first set of batteries.

First to find out, what are the loads you are trying to power, in watt hours (watts per item x hours in use)

[udect]

I Decide to use 20, 20W bulbs 6 Hours. (20*20 * 6)= 2400 for day, (this is maximum) Please can you help me to find good battery.
Thanks for you reply Mike

[Mike90250]

Great. 2400 watts draw daily. For longest battery life, you only want to deplete 20 - 25% off the battery, so 2400 x 4 = 9600 wh in the battery.


At 12V, that is a 800AH battery
at 24V only 400ah
@ 48V only 200ah of battery capacity

It's best to not wire batteries in parallel, but instead, increase the voltage and wire them in series, so 8 ea, 200ah golf cart 6V batteries in series would work just right.

You would need the same 8 batteries wired 2 series/ 4 parallel in a nightmare mash up of wire, to get 12V at 800ah

To recharge the batteries, you need to harvest 4800wh from the sun, daily. Yeah, it's a lot of PV, but adding all the losses in, that's about what you will need. Here again, a 48V system is more efficient than a 12V system.
With 4 hours of sun (assumed) you would need a 1440 watt PV array.

[Sunking]

Great. 2400 watts draw daily. For longest battery life, you only want to deplete 20 - 25% off the battery, so 2400 x 4 = 9600 wh in the battery.


At 12V, that is a 800AH battery
at 24V only 400ah
@ 48V only 200ah of battery capacity

It's best to not wire batteries in parallel, but instead, increase the voltage and wire them in series, so 8 ea, 200ah golf cart 6V batteries in series would work just right.

You would need the same 8 batteries wired 2 series/ 4 parallel in a nightmare mash up of wire, to get 12V at 800ah

To recharge the batteries, you need to harvest 4800wh from the sun, daily. Yeah, it's a lot of PV, but adding all the losses in, that's about what you will need. Here again, a 48V system is more efficient than a 12V system.
With 4 hours of sun (assumed) you would need a 1440 watt PV array.

I get the feeling this person is not going top like your answer as it is not the oe he/she was looking for. Seems to be a common theme for the last few days.

[Mike90250]

I get the feeling this person is not going top like your answer as it is not the oe he/she was looking for. Seems to be a common theme for the last few days.

Provide your answer so he has a choice

[liquidDog]

I'm also buying my first batteries. I'm going with the Costco golf cart batteries. They are 6V 225Ah. Two batteries = 12V, Four batteries = 24V. (I'm going with two banks of 24V)

I looked at the 12V marine batteries at Autoparts stores, but they are not really deep cycle (won't last long) and still just barely beat the price of the Costco batteries. ($79/ea as of earlier this month)

[Mike90250]

.. Four batteries = 24V. (I'm going with two banks of 24V)
...

Here's an article about the troubles and corrective actions for batteries in parallel.
http://www.smartgauge.co.uk/batt_con.html (connect batteries on diagonal )

[liquidDog]

I'm reading that article and trying to make sense of it. Is the basic gist that the battery cables coming from each battery bank should be equal length and connected at a single point at the parallel connection with the goal of matching resistance of the two cables?

I'm having trouble visualizing how this would eliminate the problem of one bank having higher resistance (either through a failing cell or etc) and ending up with a lower voltage than the other bank. What I have seen with Lipo batteries is to charge at full throttle and balance every three or so charges. But I'm new to Lead Acid so balancing large banks is something I haven't messed with before. I'm not sure I see a solution other than having monitoring on each bank.

[Mike90250]

With lead acid, keeping cables matched is the best solution. This helps prevent batteries from getting un-ballanced, and when they do (normal cell variation) a light equalize cycle gets them back into shape.

When cable resistance is mis-matched, the result is the bank with the least resistance, gets "worked" harder, and ages faster, and as it ages, it pulls the other bank down with it. The diagonal connections help reduce this. That's also why we say, don't mix old and new batteries, use batteries only from one lot.....