Twenty-two months ago I added a new 230ah 48v Trophy battery to our solar system. That coincided with a major upgrade to the entire solar system we have here at the glamstead. The system seriously changed our lifestyle in several ways; 1) air conditioning all night if needed, 2) bathroom electric baseboard heat 24/7 in the winter, 3) and double the AC power along with 240v capability. The system purred along flawlessly…until about 5 months ago.

Sometime in September (last year) I just happened to be in the utility room and I noticed that all batteries were charging, but the two Elite batteries (205ah 48v) were not displaying the same number of lights on the State of Charge (SOC) indicator. One was at 83% and the other was at 67% SOC but both were charging. I thought it was nothing more than a balancing issue so I basically ignored it. Ooooppppssssss…

A week later I was again in the utility room to get a tool on a cloudy day and I noticed that the lights were once again doing the same thing but not charging…it was 100% overcast. Now it got my attention. Fast forward 5 months…problem with one of our Elite batteries. From my best guess it is now at about 70 – 75% total capacity of the other Elite battery. Meaning it is now a 145 – 150ah battery. Not good, but not life endangering either. Obviously the battery has one or more weak “cells” in my way of thinking, the other cells are still doing their job.

Let me do a quick recap…I have 3 batteries in my solar system; a single 2-year old Trophy battery that is 230ah, and 2 Elite batteries that are 205ah each, totaling 640ah or 37.7kwh. Decent sized battery bank for an off-grid home. The two Elite batteries were bought at different times, 1 in early 2021, the other in late 2021. The Trophy battery was added in December 2022. All batteries match charging parameters (+/-.1volts).

I initially thought the batteries would eventually balance, match similar SOC, and maintain that for the most part. I was wrong. Each battery acts independent in charging and discharging…which actually turned out to be a blessing. The Elites generally discharge slightly faster than the Trophy and generally lag when charging. But no problems overall with maintaining a nice amount of power in the bank. Well, until I noticed the one Elite having an issue.

A visit to the shop where I bought them was warranted…for a warranty claim. (yes, pun intended) Ah, problem…the commie company in China that made the batteries was no longer around and not available to stand behind the warranty. That’s what I get for “bargain shopping” critical components. Yes, I did know what I was getting into at the time…money was an issue.

So here is where I’m at…battery bank is now at about 590ah vs 640ah. Let’s call it an 8% loss of power storage…maybe 10%. And on top of that…a weak battery with no idea for sure how long it will last. The good thing is that each battery is acting independently and doesn’t “draw-down” power from the other batteries to maintain the weak one. I guess it is a combination of the batteries’ BMS controllers and the design of the LifePo4 chemistry. But, I am still left with a somewhat bogus battery.

The owner of the shop where I bought it is also a very good friend of mine and felt terrible about the problem…but I was not the only person in the same boat…but he couldn’t stand 100% behind the warranty without the manufacturer supporting him. Unfortunate, but understandable. Given that he is a trustworthy person we came to a deal…he would do a “cost only” sale…and would do a trade for the amount due for something I had that he wanted and I could easily live without. Done! But here is where it gets interesting…

200Ah batteries are not cheap as of yet, although 100ah batteries have come down dramatically…now $800 – $1,000 all over the place. I will be the proud recipient of two of the new MidNite MNPowerflo5 Lithium Iron Phosphate server rack battery (100ah, 51.2v, 5.1kwh). The charge parameters are close enough to my existing batteries that there will be no issues. But WAIT you say! These are 100ah batteries not 200ah batteries…they won’t work!!! Ah, they will.

You see I will place the 2 new batteries together and parallel connect them together, then connect them to my Victron PowerIn bussbar unit. My system will then see the 2 new batteries as a single 200ah battery. And, each batteries BMS will control the batteries as needed during charge/discharge operations.

Here’s what the new battery bank will look like…

So a logical question would be…So these two new batteries replace the one existing weak battery? Nope!

The “weak” battery is still fully functional/operational at this point…just not maintaining its full capacity. So I will keep the weak battery in the bank and simply add the two new ones. Yup, that takes me from about approximately 590ah (30kwh) to 770ah (39kwh). Not bad, eh? And yes, I will keep a close eye on the weak battery and remove it from the bank if I notice it harming overall system operations.

Moral of the story…sometimes a problem turns into a blessing.

Also…I want to add into this conversation a point that I cannot stress enough. If you are going to have solar, especially if off-grid, it is essential to have some knowledge about how solar works…including the equipment specs and the general theories of each process step. Why? Can you imagine if a retail guy had installed the system, and I had the same problem, what would/could have been the outcome?

I can tell you this…based on people I know who were in trouble situations (i.e. not enough panels, not enough batteries, etc.) most solar companies would try and sell you a whole new system, or at least part of one) and make it sound like the only viable option. Why? Because an unknowledgeable solar system owner would have no idea that the real problem was only a single weak battery…an $1,800 fix vs laying out 10’s of thousands of dollars for stuff not needed.

Yeah, I can’t help myself…I will post about the install/upgrade and include pictures. And FYI…I got my hands on 6 more compatible solar panels so you know what that means…a new array for the system in the near future!!!

Related Articles –

• Third Battery Arrived – Trophy 220E-1
• Third Battery Arrived – Trophy 220E-1
• Great Solar Upgrade – Day #1

Q & A Time…Ask me a question or send me a message…

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