a few brief questions

[dudeman421]

OK. I have a 100w panel 90 ah 12v battery. What I have noticed is that I have estimated a capacity of only 50 AH on the battery. I am using around 24 amps/day. 1 amp running all day. What I have also noticed is that I have my high volt max set to 14 volt. and when it reaches this value, usually by noon it goes to float mode. I also notice my amps drop during this time from 3.5 to 1.7. my panel is rated at 5ish amps. I have my panel placed in an ideal location and measure the correct open voltage and current. My question is can I go with a larger or 2nd battery and still charge to full capacity since it may not go into float mode as soon. My readout on my controller says I'm producing from 20-25 amps a day, about my consumption, will increasing my usuage and capacity allow me to produce more ah. Also why is the battery so under what the rated capacity is. I have a Duracell battery marine deep cycle.. At the end of the day the battery has a full charge plus surface charge but estimating my usuage and the time it went at night things are coming up low. I have added in efficiency coefficients, dc to ac conversions and I'm not sure if I have a bad battery or if its normal to be that much underrated. I have not yet checked the at rest voltage but plan to do so tonight.

[Logan5]

Of 90AH you should not use more than 50% so you can only use 45AH, any further discharge and you damage your battery. Your array/panel is already under sized for your system, another battery is not recommended until you have more array.

[SunEagle]

I agree with Logan5. For a 90Ah battery you should have about 9 to 10 amps of charging. So 200 watt is about the right amount for that battery.

If you determine you use more watt hours a day then that 90Ah can safely provide you should increase your battery system size but also increase the solar array wattage accordingly.

[Sunking]

You have a PWM Controller robbing you blind. With a PWM controller

OUTPUT CURRENT = INPUT CURRENT

So a 100 amp panel Imp = roughly 5.5 amps. 12 volts x 5 amps = 60 watts from a 100 watt panel. You also got robbed by buying a battery panel as they cost 2 to 6 times more then GT panels $/watt.

A MPPT Controller:

OUTPUT CURRENT = Panel Wattage / Battery Voltage.

A 100 watt / 12 volts = 8.3 amps. In other words around 95 watts from a 100 watt panel

Anyway a 90 AH battery requires at least 9 amps of charge current. You need another 100 watt panel just to support the battery. However that is not enough for you. You are using more than a 90 AH battery can supply.

Good news is you get to start all over again. This time determine how many watt hours you need in a day, then you can design a system that actually works.

But here is what no one will tell you. Once you find out what it really takes, you wil realize it is just way to expensive.

[PNjunction]

Right - I hate to see a rebadged East-Penn Deka agm (Duracell rebrand) getting treated so badly.

For right now, you are running too low an absorb voltage. Change that to 14.6v pronto, not 14v.
No wonder you are dropping to float so soon.

My crystal ball says you are using a charge controller set for the "sealed" setting, which yes, is proper for a sealed GEL, (14v) but not for an agm. If it has no agm setting, then the "flooded" setting near 14.4 - 14.6v is more appropriate. In either case, see the manual for the proper *voltage* settings, and change the jumper / switch appropriately. Defaults or silk-screen markings are not always correct when it comes to choosing the proper voltage for your battery's chemistry.

Acquaint yourself with the following general charging procedures from East-Penn:

http://www.eastpenn-deka.com/assets/base/0139.pdf

Adopt the max-smoke model of solar charging with your daily cycling routine:
ALSO change your controller so that float is set just the same as absorb, that is 14.6v once again.

Basically, this forces the controller to never really drop to float voltages. You're going to need this extended absorb.
If your controller will not let you change your float voltage to high values, set it as high as you can, perhaps 13.8v might be the limit. Whatever it is, max it out.
Alternatively, if your controller allows for setting times for the various modes, make your absorb time extremely long, like 8 hours. The setting sun will be your timeout.

And, you really need a doubling of panel power. Or find a way to conserve.

To top it off (pun intended), get that poor Deka/Duracell to the nearest charger to get in probably the first real charge it has ever had in it's life.

Forgot to mention - you are cycling a "dual purpose" or even if heavy-duty trolling battery to near 50% DOD. You may only get a year out of it. ALL "thin plate" marine agm batteries, even if they have been beefed up to handle a deep discharge, or recover from it, do not have substantially longer life-cycles!

Unlike a "true" stationary deep-cycle (ie, Rolls, Trojan etc), when dealing with automotive marine dual-purpose or marine deep-cyclers, should not be taken below 25% DOD if you want to nurse 3 to 4 years from them from repetetive cycling. For that 90ah batt, that would be no more than about 22ah per day at your rate.

If you can't conserve, then at least double your panel power, and we'll see you at the battery dealer in about a year.