Solar System is now running loads

[RCpilot]

Today, I made the last few connections from the inverter to the small breaker panel I mounted next to the main load center. Most rooms in my home (12X70 Mobile) are on their own breaker so I decided to run the living room first just to see how it was going to work. The living room is actually a 12X20 add on room someone put on the place long before we bought it. I ran a 12/2WG from the inverter supplied panel to my Main load center and disconnected one circuit completely and wire nutted the three wires to the inverter supplied wire and turned it all on. So far so good. I turned a couple of lamps on, they have the CF bulbs in them, a-+ 39" wide screen LCD TV - 150W and a tower style computer that is running a 22" tube monitor. Funny though, the Forklift battery dropped down to almost 12 volts for about 15 - 30 min and then  came back up to 12.3 volts. Inverter is currently drawing 49 amps from the battery and has been holding 12.3 volts for over 4 hours now. If this was a new 1500AH battery I figure I should be able to draw 50 amps for around 25 hours or so right? I just don't understand the recovery of the battery. This is the first time since I got the battery (24V 750AH)(rewired to 12V 1500AH) that it has had a load on it. It's mostly been sitting all summer with occasional charges from a small car charger that really never brought it up much. I guess I will leave the load on it and start measuring the SG and see when it reaches between 60-80% capacity left.

[TomW]

RC;

Well, now your hooked.

The AH rating of batteries can be misleading. At least the "raw" rating. Personally, I figure that you can roughly use it to come up with ballpark figures for capacity.

One thing to remember is that a big battery bank is like a big gas tank in a car. You may be able to go a long way on a tank but you need to fill it with enough "gas" to get where you are going. A big tank allows you to "fill up" when gas is cheap [or power flows] so you do not need to waste power by dumping to protect the batteries because you have the capacity to store it.There are conversion losses all through the system, however so it is not 1:1. It can take a long time to pump a big bank to "full" but it also takes awhile to drain it to "empty". The down side to a big bank is the self discharge loss. I have seen this quoted anywhere from .1% to 1% per day and per month. I suspect it varies a lot by type, size and manufacturer.

Please note, I am not stating hard figures here. Mostly because not only does my math suck but opinions vary wildly.

I just added another 240 AH to my 24 volt bank bringing me up to 920 AH. It takes a good bit longer to pump it up but it also has better "bottom" allowing longer run times as well as never dumping excess power but storing it.

Cheers.

TomW

[DanG]

Start thinking DOD! It's very similar to Department of Defense...  "Depth of Discharge"

Batteries in general will last longer if you never try to get to the 'bottom'.

So - if you have 1500AH available you need to define just how low you will go.

Removing no/low percentages can also mean depending on incoming power as much as possible and saving discharging batteries for when solar-wind power is not available.

 

[RCpilot]

Yes, been hooked all summer! Agreed with the DOD comment. Determining the "Bottom" is my next obstacle. I don't really know how to do it. What voltage never to go under, what SG to never go under etc. I'm a newbie when it comes to all this RE stuff. So far I think I have done ok with my homemade setup but will depend on experts of this board to help guide me. The old battery I have may end up not having much capacity or it may be a good one. Today is going to be totally cloudy so I may end up having to use the inverter to charge the battery back up from "shorepower" or it may run all day with some loads on it. I don't really know where to stop drawing and start charging. I will try to get some more pictures of my "Final" setup today as it has changed from my currently posted pictures. In my living room I have a SmartUPS 2200 that I need to remove now that it shouldn't be needed anymore and that will save me some power as it is always charging it's own batteries. I will begin the quest to learn how to get more power out of what I have by killing "phantom" loads, etc. I tried contacting GNB last week and ended up with someone's phone number that I didn't have time to get back to. I wanted to try to get a spec sheet on my particular battery so I can learn more about it and to properly setup the Xantrex Prosine's charge curves. If anyone knows from this page which doc I need let me know. I have searched the site for my battery model and came up with nothing.


Exide Battery Spec Sheet Selection Chart


My battery has these numbers on it:


Model: M1601212513A


Cells: 12


Volts 25.2 (battery is now paralleled into a 12 Volt setup)


Weight: 1354Lbs


AH:  750 (Should now be double right?)
S/N: GHA2103


Thanks for the comments everyone!  Kelly

[RP]

Well done Kelly!

I wonder if the load caused a little warming of the electrolyte which may have "stirred" it up a little causing the voltage to rise after a short time.

[RCpilot]

Thanks RP, hope all is going well with you. I ran the battery basically with no charge for about 18 hours with anywhere from 30-50 amps on it and decided it was too low and set it to charge using grid power with the inverter. It took about 7 hours for the inverter to charge it back up but now, the voltage is sitting higher than it was before I started. So, I will make another run with some loads and see if it lasts any longer. Maybe a few fairly deep cycles will "Open" it up and the capacity will come up some more. Still learning.....
Kelly