Back in the summer of 2015, I published a post and video detailing how I test and maintain my RV batteries. I have the cheaper “wet cell type” golf cart batteries. They are a tried and true power source for boondocking but do take a bit of effort to keep them performing at their best and prolong lifespan.
At the time one thing I left out was a process called “Equalization.” It wasn’t until I installed the sophisticated Bogart battery monitor/solar controller combination that I gained the ability to equalize my batteries. You’ll find many of the better quality solar controllers will have an equalization function.
What is Equalization of Lead Acid Batteries?
Here is a quote from the Bogart solar charge controller technical manual:
Equalization is a process of overcharging a battery that in the past may have been undercharged. Undercharging can cause “sulfation” of the battery which will cause it to lose some capacity to hold energy. Equalization is an overcharge that can help restore the damage done by undercharging. For example, you might want to do this if a reading with a hydrometer of the specific gravity of the battery electrolyte is lower than what the battery manufacturer recommends.
In real-world dry camping situations, we often can’t get our battery banks fully charged each day, sometimes for days at a time. Solar does a great job, but once multiple cloudy days show up, our batteries fall short of a 100% recharge.
Running a generator through a charge controller would take too long and who wants to listen to one all day. Also, many campsites have limited generator running hours. So often, we have to be satisfied with less than a full charge at the end of the day.
Over time the lead-acid battery lead plates will sulfate and reduce our battery banks total capacity. Equalization will remove the sulfate crystals that build up robbing capacity. It also causes the batteries to vigorously bubble which stirs up the liquid in the cells remixing the water and electrolyte that can become separated over time.
Here is a link to an in-depth article on Battery Equalization I found. Also another one from the US Battery company. Note: You’ll find a section of the PKYS.com article has an important caveat. Equalization is not without its drawbacks and should only be performed when necessary.
Equalizing the batteries is a tool that can be used to rejuvenate tired batteries or to prevent batteries from becoming tired. As a tool it is a double edged sword of course, this removal of the outer layer of the plates reduces their size and volume and thus their longevity. The material removed will fall to the bottom and may eventually short out the plates. I find that the best way to decide on whether to equalize and how often is to consult the information from the relevant battery manufacturer. You will find different opinions even among battery manufacturers on the way equalization is to be carried out. – http://shop.pkys.com/Battery-Equalization_ep_44.html
When and How I Equalize
I like to do thorough testing of my battery bank about once or twice a month, pulling the caps and testing each cell with my hydrometer. If I find some of the cells are falling out of the good zone and into the fair zone, I run a manual equalization using my Trimetric battery monitor. I’m finding that I need to equalize roughly every three months when we are heavily boondocking, much less if sitting on full hookups.
My Trimetric monitor works in tandem with its companion Bogart SC2030 solar charger controller. They communicate via a telephone setup data cable. The Trimetric displays the days since I last equalized. Here is the process as described in the Bogart Controller’s technical manual
How to initiate or terminate the equalization process: 1. Use the SELECT button to observe the “Days Since Equalize” display. This is one of the “Extra data” items shown at the bottom portion of the front panel label of the TM2030. The display will show “dSE” (Days Since Equalized) alternating with a number of days. 2. Hold the RESET button down for about 5 seconds to reset the Days to 0.0. If they are already 0.0, then this step need not be taken. 3. With 0.0 showing in display, push RESET again for about 5 seconds—it will show “Equ”. This initiates the equalization described above. If it is desired to terminate the process, use SELECT to again get to this display, which will be show “Equ” unless the equalization step has ended push the RESET button for 5 or so seconds and it will go to “0.0” thus terminating the equalization. To lengthen the process, you may then restart at any time.
When I equalize the batteries, it can take several hours or more. During that time I want to have full sun on the panels. So what I do is pick a day when I know I will have a fully charged battery bank early in the day. Then if the forecast is for sunny weather, I initialize the EQU mode and let her go. Usually, it will take anywhere from 3 – 5 hours to complete.
Once completed I remeasure all the cells and generally find they have all returned to the good zone on my hydrometer, measuring in the 1.265 specific gravity range as expected for a lead-acid battery. We are ready to continue our boondocking adventures with tip-top battery life. 🙂
Lead acid batteries are full of sulfuric acid which is a nasty substance to get on your skin, clothes or in your eyes. Also during the equalization process, the batteries will bubble and produce more gas than usual. Here are a few safety precautions I take:
- Wear old clothes – battery acid drops will eat holes in clothes
- Wear eye protection
- Wear rubber gloves
- Leave the battery box and storage bay door wide open for max ventilation
- Check and make sure the batteries aren’t getting too hot
- Hang around and monitor the process
Video Detailing Testing and Equalizing My RV Battery Bank
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