Confused about SOC on TriMetric 2025A

Hi Everyone,

This is my first post and I'm a complete Newbie. I currently have a setup that has 12 6volt Golf Cart batteries connected in series/parallel to a TriMetric 2025A and a 5000W PSW Inverter. I also have a Rogue MPT 3024 waiting for my Panels to be completed. I use this setup for all the power needs of a small travel trailer. The biggest load in the trailer is the 3.2 cu ft refrigerator/freezer. I do not have any solar panels at this point (building them myself later this month) and charge my batteries from a 8000w AC generator and a Car battery Charger.

My confusion stems from the readings on the TriMetric. It will read 12.6v with -00.1 AH and 65 POC after the charger has been running for several hours. When I disconnect the generator and run off the batteries the voltage will drop to about 12.2v after 10-12 hrs of operating off the batteries. The AH will stay the same and the POC will drop 15-20%. I confirmed that the charger is working and the Voltage will increase once connected to the generator again. But, the AH doesn't change and the POC does not increase.

Appreciate the benefit of your expertise.

Comments

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Confused about SOC on TriMetric 2025A

    Welcome to the forum.

    Let's look at some of the aspects of your system, starting with twelve 6 Volt batteries. The Voltage reading you give indicate this is a 12 Volt system, correct? if so you have one big problem to begin with: trying to keep the current flow even in and out of six parallel banks of batteries. Related to this is the fact that would be about 1320 Amp hours @ 12 Volts. That bank would require about 132 Amps of charge current @ 14.4 Volts, or 1900 Watts of power to charge. Your vehicle alternator isn't going to do that. I don't know what you're using for a battery charger but it probably can't manage that either.

    Basically it looks like your batteries are chronically under-charged and may be hopelessly damaged already. Disconnect and inspect: check the specific gravity of each and every cell. Recharge them in 12 Volt groups of two batteries only. You probably don't have any method of applying an equalizing charge, but they probably need that as well. You need to read the Battery FAQ's: http://www.windsun.com/Batteries/Battery_FAQ.htm

    You also need to evaluate your loads carefully and determine how much power you really need. It is probably not nearly 8 kW hours of battery. Getting this under control will make everything else go a lot more smoothly.

    I don't know of any pure sine inverter that is 12 Volt and 5 kW. If it says "AIMS" on it, toss it in the trash and buy a real one. You probably don't need 5 kW of inverter either.

    If your system is 24 Volt (you mention a Rogue 3024) you still have these problems, only not so much so.

    As for making your own panels ... Do you want me to provide links to the three threads of the past week describing the frustrating nightmare that is this process? How much of a masochist are you? It is a prime criterion for making your own panels. :roll:
  • System2System2 Posts: 6,290 admin
    Re: Confused about SOC on TriMetric 2025A

    Thanks for the insight. I will let you know what the results of your suggestions are.
  • cptdondocptdondo Solar Expert Posts: 76 ✭✭✭
    Re: Confused about SOC on TriMetric 2025A

    I'm not sure why you need all those batteries. I have a small RV with an electric fridge, a computer based entertainment system, and a few other things. I have 2 T-135 batteries that provide all the power I need for 2-3 days of normal "boondock" use without any extreme conservation measures. I have a single 12V deep cycle battery that is the backup which provides 1 night of furnace and lights when the primary bank is exhausted. I could probably go 5-6 days if I went to significant lengths to conserve power.

    I have no idea why you need 12 golf cart batteries and all that power. I suggest you start with a power inventory; just how much power do you need? And where best to spend your money?
  • icarusicarus Solar Expert Posts: 5,355 ✭✭✭✭
    Re: Confused about SOC on TriMetric 2025A

    It sounds like you have toasted the batteries, probably due to a number of mistkes, some of which 'coot mentioned.

    Additionally, your battery charger is not right for such charging. ~1500 ah of battery is going to need a minimum of 150 amps, and should have more like 300 amps of cahrge current. Additionally, auto type chargers do not handle bulk/absorb/float/eq charging very well.

    I suggest before you don anything else, you read, and understnd the following links:

    http://www.windsun.com/Batteries/Battery_FAQ.htm#Lifespan%20of%20Batteries

    http://www.batteryfaq.org/

    My guess is you have 1000 lbs of lead scrap at present.

    Sorry to be the beare of bad news.

    By the way, welcome to the forum. There are some very sharp folks here who have forgotten more about PV than most of us will know. Newbies do well by listening to their advice. I might lso second 'coot's notion that if you are expecting to charge 1500 ah of batteries from home made panels,, the chances are slim. I would also add, why so many batteries? We live full time off grid with only 4 T 105s. (granted we have a propane fridge)

    Good luck and keep in touch.

    Tony
  • System2System2 Posts: 6,290 admin
    Re: Confused about SOC on TriMetric 2025A

    Thanks for all the replies. I took Coots advice and paired down the batteries after confirming that the specific gravity was good on each of the individual cells. I got the batteries second hand for a really great price so I bought them with the idea that I may not need all of them now but as my load increases I could put them to use. Also, I live in this travel trailer all year round I have no other habitat. I have looked at the information in the forum a couple of times and while I can follow it in general I'm sure I am missing a lot of the nuances of the material. As for building the panels it's something that I want to do as a learning experience and as a skills development project. I realize that the charger I am currently using doesn't do the proper job and it is a stop gap until I get the panels built and connected to the Rogue Controller. Thanks again for all the comments and I am sure I will be posting again soon.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Confused about SOC on TriMetric 2025A

    If you're going to hang on to those extra batteries you'll have to check them and recharge them periodically (at least once a month) so they don't die from self-discharge. Batteries have a finite life whether or not they are in use. Kept charged and not used they could hang around for a long time. Left on their own they'll be scrap metal inside of three years.
  • System2System2 Posts: 6,290 admin
    Re: Confused about SOC on TriMetric 2025A

    Thanks Coot for the tip on the batteries, and thanks to everyone who replied. That's consistent with what I read in the battery info and other pieces online. I will update the forum on my panels once they are complete. In the meantime I will continue to absorb the info from the other posts..
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