Melted Battery Terminal

Our power shut off rather abruptly around 8pm this past Wednesday. The convection oven was running so I thought perhaps a perfect storm of the water pump and fridge compressor kicking on at the same time may have managed to trip our main breaker. Going outside to check out on our electric panel I was met by a disconcerting burning smell emanating from the battery bank enclosure. Opening up the box I found one of the terminals smoking and significantly melted. Shutting everything down we used candles for the rest of the evening.

Melted cable and battery terminal

The next morning I pulled the battery with the melted terminal out of the bank and confirmed that it would definitely not work in its current state.

Yes, definitely not going to work. I would learn later that the melted part of the terminal is called the flag and it is possible to replace it but more on that later.

Next came a series of phone calls:

  • Northern Arizona Wind and Sun (the distributor I bought the batteries from)
    • Me: These Rolls Surrette batteries have a 3 year warranty. Is a melted terminal covered?
    • Them: I don’t know I can contact the manufacturer.
    • Me: How long will that take?
    • Them: Possibly a couple of weeks.
  • A Rolls Surrette Distributor in San Antonio
    • Me: Do you have and Rolls Surrette L16 445 amp hour batteries?
    • Them: We’re out of stock. Some may come in around the middle of March. I’ll check if our Corpus Christi branch has any and call you back.
  • Rolls Surrette (The manufacturer)
    • Me: Would a melted battery terminal be covered under the warranty?
    • Them: Probably not as it most likely melted due to a loose connection. However, the old flag can be ground off and a new one welded on. Call the Rolls Surrette distributor in Dallas.
  • The Rolls Surrette Distributor in Dallas
    • Left a message and still haven’t gotten a call back

I did a google search for industrial batteries in my area and made some more calls asking if they had L16 batteries

  • The first one didn’t know but took my number and said she would call me back.
  • The second one had never heard of an L16 battery
  • The third had some smaller 220 amp hour batteries and one 390 amp hour battery.
  • The fourth one had nine 390 amp hour batteries.

As my options seemed limited I decided on the fourth one even with the downside of having a smaller capacity battery. A battery bank’s total capacity is limited by the smallest capacity battery in the bank.

Eight 6-volt 445 amp hours batteries in series have a capacity according to the following formula:

48 Volts X 445 Amp hours = 21360 watt hours or 21.36 kilowatt hours

Seven 6-volt 445 amp hour and 1 6-volt 390 amp hour batteries in series have a capacity:

48 Volts X 390 Amp hours = 18720 watt hours or 18.72 kilowatt hours

So, I lose out on 2.64 kilowatt hours or realistically 1.32 kilowatt hours since I wouldn’t discharge the batteries below 50%.

Meanwhile, Northern Arizona Wind and Sun had emailed me back torque specifications for the Rolls Surrette battery terminals and said that they would send me a replacement flag. So, I decided to hold on to the old battery rather than turning it in for a core charge.

Around 11 am I broke off my battery hunt to meet the county septic inspector. More on the septic system in another post but not to keep you in suspense, we passed.

With that taken care of I headed to the north side of town to pick up the battery. The store manager was personable and pretty chatty so we had a good natter about batteries and solar power setups. When I’m ready to replace this battery bank, (hopefully not sooner than 5-7 years from now) I think I’ll check in with him.

I wedged the 60 lb battery safely in my back seat so if I made a hard turn I wouldn’t end up having to clean sulfuric acid out of the upholstery. I didn’t think about it but I was also carrying a 5 gallon canister of diesel and a 15 pound propane tank. Maybe I should get one of those hazard diamond stickers for the Honda Fit.

Back at the cabin I fabricated another battery cable to replace the cooked one. The terminal on another battery had some corrosion so I cleaned it off and then installed the new battery. The charge controller and inverter fired up without a problem and we were back in business. There’s only a minor issue that system is still not reporting a state of charge. That’s a percentage approximation of remaining battery power. Calculating remaining power in battery is a bit of dark art and the state of charge can be wildly inaccurate so not a huge loss. I do miss out on the smug satisfaction I get when I see it tick up to 100% on a sunny day and then going around and turning on every light and electric appliance in the house with careless abandon.

This was the only corroded terminal. I cleaned it off and covered it in dielectric grease.
The replacement
It looks like an A&M color scheme has crept into my Texas Tech motif