Voltage Question

[Bigbear]

I have a morning star 30, 4-130 Kyocera, 8- Basement Watchdog batteries, the larger one that I believe to be about 120 amphr.  We have run on six of these batteries for a couple weeks now, and by morning, after showers, TV, lights and a 3 min. run of a hair dryer set on med, and small fan run all night the Morning Star says half full.  The voltage was at 12.2, the night before it would settle down to about 12.5 .  I thought by adding 2 more batteries, it might still read full by the time we left for work.  The morning voltage reading now is about 12.3 and still drops down to the half full light.  Am I doing something wrong, or just asking to much of only 8 batteries.  Thanks, BEAR  

[Titantornado]

I'm certainly no expert on the subject, so take it with a grain of salt.  

I think you're relying way too much on the indicated voltage of the batteries, and that's not a great indicator of actually battery capacity. And the Morningstar controller uses the same method to determine battery capacity, and can be easily fooled. (via voltage drops in wiring and connections)   Flux just posted a few thoughts about battery condition vs. voltage just a few days ago here: http://www.fieldlines.com/comments/2006/8/15/142422/138/3#3  If you really want to know what state they are really in, ya got to take a hydrometer reading.

[Clifford]

It sounds like you are sucking a lot of power.  It is possibly that you are coming close to the full capacity of your system.

Many controllers will monitor both input & output, but they must be able to handle the amps...   Perhaps that is an advantage of getting a big combo controller/inverter.  Although, I also don't like running my inverter when I don't need it.

Make sure you are actually able to get the batteries over 13V (or more) during the day.  I have damaged a couple of my batteries by keeping them between 11.5 and 12.5V last winter.

Every once in a while you may bump into BIG used Telco/UPS system batteries.  I believe that John can still find some large UPS batteries in Kansas City:

http://www.fieldlines.com/story/2005/9/27/19944/7027

I got some large EXIDE batteries facilitiated by him.  They are NICE, although it is taking me a while to get them back up to full charge.