Crown cr430 charging recommendations

Rick-nzRick-nz Registered Users Posts: 2
Hi all,

I originally got into the solar hobby when we had a 7.1 earthquake and were without power for a week. since then I have slowly been growing my system which started off as 2x 85w panels, 1000w pure sine wave inverter and 195ah 12v agm battery which was enough to run a small fridge and run a small tv for a hour a day.

We are in the process of doing a major revamp of our wee solar system. We have a hydrometer on the way as well as a vfx3024e, hub 10 and mate3. We have just picked up 4x cr430's, This is my first taste of wet battery's and want to make sure I do it right. So I would like some help with the recommended voltages to start with for charging them.

Cheers
Rick

Comments

  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    Re: Crown cr430 charging recommendations
    Rick-nz wrote: »
    We have just picked up 4x cr430's, This is my first taste of wet battery's and want to make sure I do it right. So I would like some help with the recommended voltages to start with for charging them.

    Welcome to the forum,
    I just looked at the data sheet for those batteries. They don't give recommendations for RE type charging. RE batteries are a niche market... most deep cycle batteries (golf cart, floor scrubber, forklift, telecom, etc) are charged from the grid. The grid offers unlimited time and energy to charge the batteries. Every time you charge the batteries from the grid, you charge them all the way. This is NOT how you will be charging your batteries.

    The charging profile that Crown recommends is not possible with RE equipment. btw, many battery manufacturers use the terms 'bulk' and 'absorb' differently than RE equipment manufacturers such as Outback.

    You are very fortunate to have flooded batteries... you can figure out for yourself (use hydrometer) what works. You have only two variables to play with: absorb voltage and absorb time. Your goal is to find out what is the minimum voltage and minimum time that will get the SG up to 1.275.

    High voltages and long times at high voltage are hard on batteries. Therefore you don't want to do any more of that than you have to. On the other hand, too low a voltage or too short a time will lead to sulfation, the commonest cause of battery abuse. One thing that is important is to prevent stratification from progressing. You do this by 'overcharging' the battery at high voltage to cause gassing which stirs the electrolyte.

    The tall batteries, such as your Crowns, really need to be stirred. Stratification occurs during both charging and discharging. Stratification is only broken up by gassing. Partial State of Charge (PSOC) charging, typical of RE systems, ratchets up the stratification with each partial charge and discharge.

    In a stratified battery, the sulfuric acid is concentrated in the lower part of the battery. The electrochemical potential at the bottom of the plates is higher than at the top of the plates and that means the bottoms of the plates are discharging themselves into the tops of the plates. It takes higher voltage from your charger to charge the bottoms of the plates. Stratification corrodes and sulfates the lower portions of the plates.

    Crown's daily charging recommendations call for a long initial phase of charging at a relatively low voltage, followed by a finish charge at constant current. Constant current will drive the voltage very high... up to 32 volts daily. (RE chargers don't do constant current). This daily finish charge helps stir the electrolyte. Even with this daily stirring, Crown recommends a weekly equalization (which really stirs it up).

    You probably won't be able to get SG up to 1.275 on a daily basis, and even if you can, it's not necessarily a good thing because of the long times at high voltages. A lot depends on how low the SOC is. The lower the SOC, the more important it is to get to 100% in a day. For typical, shallow RE discharging, you should drive the SG up to 1.275 a couple of times per week.

    My advice:
    1) read about hydrometers... there are a few things to learn about using them.

    2) get a battery monitor... you will learn to correlate voltage and current (especially 'end amps') with SOC and SG.

    3) read about how to commission the battery bank... use a generator if necessary.

    I have no personal experience with those batteries (I'm still on my first set of batteries). I would venture to guess that absorb voltage of 29.6 would be a good starting point for those batteries.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • Rick-nzRick-nz Registered Users Posts: 2
    Re: Crown cr430 charging recommendations

    Thanks vtmaps for your help.

    i see you recommend a battery monitor for the batteries. do you have any experience with the outback flexnet dc, I take it this would tell me just about everything apart from sg?

    Cheers
    Rick
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    Re: Crown cr430 charging recommendations
    Rick-nz wrote: »
    i see you recommend a battery monitor for the batteries. do you have any experience with the outback flexnet dc, I take it this would tell me just about everything apart from sg?

    No, I don't have the flexnet DC:cry:

    Its a good unit, but not without its idiosyncrasies. Check out the Outback forum. This thread discusses some of the issues... there is a bug that is of little consequence UNLESS you are trying to use automatic generator start (AGS):

    http://www.outbackpower.com/forum/viewtopic.php?f=28&t=7448

    Kent Osterberg & Tallgirl (both of whom occasional visit this forum) have contributed to the thread and they are very very smart.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • Chuck46Chuck46 Solar Expert Posts: 95
    Re: Crown cr430 charging recommendations

    I am using these batteries right now. When I installed them I called the factory and had a long discussion with one of their service engineers. They had no time recommendations and suggested the same process with a hydrometer. Voltage recommendations were absorb 29.7 float 26.5 and equalize 31.2. I found my best ending amps at 10 and time at 6.7 hours. It does not reach the full absorb each day and floats every 3rd day on the average. To come to this I measured sg every hour until I reached the 1275. According to the engineer 1275 to 1280 is fully charged. It took me several months to get things working well. Hope some of this helps

    Chuck
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