Know Your Battery’s Water-Fill Level
Anyone who has a set of deep-cycle flooded lead-acid batteries knows that proper maintenance includes checking the water level in each cell, after a full charge. Although it’s easy to carefully add water to each cell, many people get confused as to how much water to add. Too little, and they’ll be having to add more sooner than is necessary. Too much and it runs the risk of overflowing when the batteries are charging.
The proper method recommended by most battery manufacturers is to add enough water so that the cell plates are completely submerged, but not so much that the water is up to the battery case cell cap vents. The proper fill level, according to battery manufacturers, is approximately 1/4-inch below the fill well bottom. (See photo example)
Battery manufacturers also recommend using only distilled or deionized water and to use a watering gun or pitcher to fill each battery cell. Ensuring your batteries are properly watered will add life and provide optimum performance from your deep-cycle batteries. For more information on battery maintenance, visit www.usbattery.com.
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I have two Interstate deep cycle rv batteries 3 yrs old. Notice they don’t hold a good charge lately. I keep the battery save switch off when not in use. I’ve been confused about the water level and after reading your post I realized I was filling too much water (almost io to the top) Could this be the issue?
Hi Bobby, Adding too much water shouldn’t cause an issue unless over-filling is causing the cells to overflow. Any significant overflow could cause loss of acid and this would impact the batteries’ ability to hold a charge. If you have a hydrometer, you should check the specific gravity after charging to make sure they are charging fully. Our engineers were wondering how long do the batteries generally go between uses, and what kind of charger are you using?
I’ve had my two US Battery six-volt batteries (US 145XC) for almost seven years now and have maintained the water levels on them yearly and put a maintenance charger on them during winter. They have served me well. MUST check the levels, and only use distilled water.
what is causing my batteries to sizzle? Could it be the water level is to full?
Hi Karen,
The most likely reason is due to charging. Gassing/bubbling is normal during the end phase of charging as the voltage is at the highest point. The gassing/bubbling mixes the electrolyte to ensure it is homogeneous throughout the battery. If the battery is bubbling when charging hasn’t recently occurred then it could be a short in one of the cells. It would be really obvious since the bubbling would be in only one of the cells. 99% of the time the bubbling is happening for the right reason.
Hey there, I have 6 12v batteries I fill 3 sections each with water.. running in parallel.
I’m in the north where we have far below freezing temps all winter. Do I need to remove the water completely from each section for the winter? Will u still be able to use to batteries for lights in the cabin over the winter? Cheers!
Hi Wes,
Make sure to top off all 6 cells of each battery to the proper fill line using only distilled water. Our engineers do not recommend that you remove the electrolyte during the winter. However, they do recommend limiting your depth of discharge based on your ambient temperature. Using the freezing point chart below and your average ambient temperature, determine your state of charge lower limit. If you discharge your battery below that state of charge, you risk freezing your batteries. Frozen batteries are typically permanently damaged.
Best,
-Mike Wallace, Creative Manager
Hey, I got a brand new 12v pre charged battery for my quad and it didnt work, I tried charging it and still nothing. I took it apart and found that there was barely any water. I filled it up and charged and it held a voltage. But, when I put it in my quad it didnt turn over and smoke came out of my battery. Any idea on how and why this happened?
Hello Noah,
Thank you for choosing US Battery for your quad! We’re sorry to hear about your premature battery failure.
Our engineers need some additional information to accurately diagnose your situation:
1. Battery model
2. Date code
3. Voltage before trying to turn it over.
4. If your battery is a flooded lead acid, please provide the specific gravities of each cell. You can use an EZRED battery hydrometer they are cheap and easy to use.
Please send this information to our Product Engineer Matthew Ealy mealy@usbattery.com
Best,
-Mike Wallace, Creative Manager
I have an Interstate 24f 750 CCA battery that I bought in November of 2018. It is a 6 year battery. As of 9-21-2021 it will not hold a charge. I put a battery charger on it for and after an hour the indicator of the charger show it fully charged. I turned the key and the car cranked right up and then turn it off. But when I went out an hour later to see if the charge held, it did not and it will not crank up. I hooked the battery to the battery charger and the indicator on the charger showed that the charge had gone down again. So recharged for fan hour. After that hour it showed fully charged. Then I took it off the charger and waited an hour. After that hour it would not crank up. I hooked it to the battery charger and once again the indicator showed the charge had gone way down. Why is it not holding a charge? I checked the water level in the 6 chambers. It is a tiny bit low. I live in southern Georgia so our winters are very mild. Could it be the battery is shot and just needs to be replaced? Thank you for any comments or suggestions. Mark.
Hi Mark,
Our engineers believe that you’ll most likely need to replace the battery, especially since it is losing its charge and then recharging quickly. If you have not used a hydrometer to check the specific gravity of the cells, you should check them. Each cell should read at least 1.265 after a full charge. If you don’t have a hydrometer they are pretty inexpensive, this E-Z Red hydrometer works well.
Best,
-Mike Wallace, Director of Marketing
I have 2 brand new Everstart 29DC deep discharge batteries for use in an Inverter/Charger system. The fluid levels as purchased are just high enough for the fluid to touch the bottoms of the fill wells so that the reflection from it distorts due to capillary action. Is this the proper level, or should it be raised 1/4 inch?
Hi Tom,
I would recommend contacting Clarios/Johnson Controls, they manufacture your batteries. For our products, the water level would be too high, but they may have different recommendations for their products.
Best,
-Mike Wallace, Director of Marketing
Purchased 4- US12VRX with date code A2X on 2/17/2022. The inside of the batteries are black like old batteries would look like. Fill caps were white to start and after the first charge they were all black. Is this normal or is there a problem.
Thanks
Hi Brent,
The inside of each battery cell is already black and grey when they leave our facility, that is their natural color. White or light-colored groups would be a sign of mossing or sulfation. Both would lead to decreased performance or premature failure.
The black material settling on the bottom of the caps is the oil leaching from the separators. It will not cause any performance issues. The oil can be cleaned from the caps if desired.
Best,
-Mike Wallace, Director of Marketing