By Greg Illes
Sometimes batteries seem ridiculously simple—we tend to see them as either working or dead. But there is way more than meets the eye in this 2,000-year-old technology. [According to panasonic.com: The “Baghdad Battery” – ceramic pot battery and the world’s oldest “ceramic pot battery” was discovered in the remains of Khu jut Rabu, a village in the outskirts of the Iraqi capital Baghdad. This battery is more than 2,000 years old.]
RV batteries are made with lead plates interleaved with lead-dioxide plates. The plates are immersed in sulfuric acid, and the electrochemical reaction creates the battery effect. The whole bundle is wrapped up in a big plastic box with the electrical terminals on top.
As current is drawn from the battery, a chemical change occurs which causes both plates to begin to change into lead sulfate. Normally when the battery is recharged, the lead sulfate layer is converted back into lead and lead dioxide.
This is where a major wrinkle arises. After extended use or even prolonged storage, some of that lead sulfate begins to change from a fine-grained powder-like state into crystals. The crystalline structure prevents the lead sulfate from changing back into lead and lead dioxide, and the battery is described as “sulfated.” This is literally the beginning of the end of a battery’s life. When enough sulfation builds up, the battery plates become increasingly unable to perform their function – the battery becomes a very expensive, acid-filled boat anchor.
Because a battery in storage has a self-discharge component, it is common to find heavy sulfation occurring in fresh batteries after extended storage. Frequent discharge/recharge cycles are actually good for a battery because it does not provide time for the sulfate crystallization to occur. You can avoid the worst of sulfation influences by keeping batteries fully charged as much as possible, and never storing a discharged battery.
Once sulfated, batteries at one time were relegated to the recycle bin. However, there are affordable devices that deliver a specialized pulse-charging current. These battery chargers and maintainers (sometimes called desulfators) are sold by a number of vendors. A predominant player in this area is BatteryMINDer®, providing multiple models priced from $50-$300. See Amazon.com and automotive websites for details and reviews.
Keeping your batteries connected to a desulfator while stored is one of the best methods to prolong battery life, not to mention that it will keep your batteries at full charge for your next use.
For a lot more detail on batteries, there’s a terrific write-up in Wikipedia.
Photos: Greg Illes
Greg Illes is a retired systems engineer who loves thinking up RV upgrades and modifications. When he’s not working on his motorhome, he’s traveling in it. You can follow his blog at www.divver-city.com/blog.
##RVDT1972
I can recommend a YouTube channel called “Sweet Project Cars”, a lot of smart stuff there. One thing I saw was how he takes care of batteries.
https://youtu.be/KzOQH1twpI8
An excellent description of the science/chemistry behind sulfation in lead-acid batteries & how to minimize it.- http://www.bogartengineering.com/amp-hrs-based-charging-control.html
Should be titled taking care of lead acid batteries
Batteries are a 2,000 year old technology?🤣 You been watching the history channel again 🤔
Thanks for your comment, Gary. Here’s a quote from panasonic.com: “The ‘Baghdad Battery’ – ceramic pot battery and the world’s oldest ‘ceramic pot battery’ was discovered in the remains of Khu jut Rabu, a village in the outskirts of the Iraqi capital Baghdad. This battery is more than 2,000 years old.” Have a great day. 😀 –Diane
Does the sulfate you describe only happen in a flooded cell battery and not in an AGM battery?
Hi Crowman, thats a great question as I was thinking the same, hopefully we will get our answer!
Snoopy
Sulfation affects all lead-acid batteries – flooded, AGM, Gel. Lead sulfate is a byproduct of the discharge process. If not converted to sulfuric acid promptly by recharging, the lead sulfate will become a permanent coating on the plates and reduce battery capacity.
Thanks Ken!
Snoopy
Glad you cleared this up wasn’t sure if it was just flooded cell.
The last sentence in the first paragraph says it all: “2,000-year-old technology.” The development of Lithium ion batteries came to a head in 1990. Lithium batteries are so much better than lead acid for several reasons. If you are spending thousands of dollars on an RV, spend a thousand more and get 2 Lithium batteries. You’ll be glad you did.
My trailer has three batteries, Can I use one tender or do I need three?
If your batteries are connected in parallel or series, you only need one tender
20 years of teaching automotive technology classes, I have been through this lecture many times yet, it still amazes me to see even experienced mechanics mis-diagnose battery problems. A simple DVOM will tell you a lot about a battery.
As a newbie here…
What is a “DVOM” and how does one use it?
DVOM= digital volt, ohm meter. An accurate way of reading the volts and current flow and resistance of an electrical circuit.