The Purpose of Battery Equalizing vs. a Battery Equalizer

battery equilizer

Deep-cycle battery banks are regularly recharged using a three-step charging algorithm (bulk, absorption, float). The bank is considered to be fully recharged at the end of the bulk stage, which uses a “gentle” high voltage charge that minimizes out-gassing. However, while battery ampacity may be substantially restored during the bulk stage, plates may not be fully desulfated, and the electrolyte may not be adequately mixed. Over time, these conditions lead to plate deterioration and reduced battery performance.

Battery equalizing (or battery equalization) is a periodic maintenance function primarily used for flooded-cell lead-acid (FLA) deep cycle battery banks. A higher-than bulk stage voltage is applied for several hours to vigorously agitate the electrolyte to complete desulphation and to stir up the electrolyte, equalizing its specific gravity from top to bottom. Applied periodically (~monthly) peak battery performance is maintained and battery life expectancy is improved. However, the battery bank usually out-gasses during this exercise, so the electrolyte levels must be monitored and batteries stored indoors should be vented to the outside.

Some RVs contain 24V electrical systems, where two 12V batteries are wired in series. This is a particularly handy configuration for efficiently powering large loads, especially via an inverter. However, some house loads (stereo, LED lights, etc.) may still be good old 12V items. When these loads are active, they typically discharge from a single battery, resulting in one of the series-connected battery’s state of charge being different from the other.

A battery equalizer is a device that is permanently wired into the RV’s electrical system. It can direct current from the second battery to help the 12V load battery power those loads, and it can vary charge current from the alternator to the two batteries. These two features help keep the battery states of charge “equalized,” resulting in better battery performance and longer life, and perhaps even preventing battery damage.

Give us a call at Inverter Service Center at 1-800-621-1271, and we’ll be happy to discuss battery equalization and battery equalizing purposes, procedures and products with you.

About the Author – Jim Goodnight – also known as “crewzer” — is a retired solar industry application engineer, product manager, and forum moderator and has previously written for Home Power and Solar Professional magazines.

Comparing Rechargeable Battery Technology

lithium ion battery chemistry

The most common rechargeable battery chemistry by far is the lead-acid battery (LAB), also known as the Planté battery, which dates back to the mid-nineteenth century. But, before delving into the details of this battery type, let’s first discuss an increasingly popular newcomer, the Lithium-Ion battery, or LIB.

LIBs have seen considerable development and application growth over the past several decades. Their energy density — meaning the amount of power stored versus the physical size — is relatively high compared to LABs, and they too are available in several varieties, each with its pros, cons, and optimal applications. Popular LIB applications include personal electronics, cordless power tools, and electric vehicles.

A newer LIB technology is Lithium Iron Phosphate (LFP or LiFePo), and it’s experiencing growing attention in marine, RV, and solar applications. LFP batteries offer high energy density, high current ratings, withstand deep discharges, and deliver long cycle life. On the other hand, they are sensitive to over- and under-charging, they typically require a battery management system between the charging source and the batteries, maintenance and replacements are not yet readily available, and the initial investment is very expensive. However, their compatibility, availability, and cost should all improve in the next few years.

The Most Popular Battery Type: LABs

Despite LIB inroads, LABs currently remain the most popular battery type for automotive and recreational use. LABs are dependable, their sizes and attachment points are reasonably standardized, new and replacement units are widely and readily available, there’s an established network for returns and recycling, and pricing is competitive.

LABs all operate essentially the same way: the internal lead plates and sulfuric acid (hence the lead-acid moniker) interact to create lead sulfate, diluted sulfuric acid, and direct current electricity when discharging. When recharged, the lead plates are restored (mostly) and the acid re-concentrated. The battery is once again ready for use.

LABs are generally available in two construction types: flooded-cell and sealed. Within each of these types, there are three application versions: starting-lighting-ignition (SLI), deep-cycle, and hybrid. Regardless of type or version, they share similar architectures, with three nominal 2.1V cells connected in series to form a 6V battery and six cells arranged to form a 12V battery. Batteries of the same size, type and version can be wired in series to increase voltage, or in parallel to increase Ampere-hour (Ah) capacity.

Flooded-cell LABs are the most well known. SLI versions are the starting batteries found in most vehicles. These versions excel at delivering the short bursts of high current needed to start an engine – particularly useful at low ambient temperatures – but their plate structure renders them unsuitable for deep-cycle applications.

Deep-cycle flooded-cell LABs are very good at delivering hundreds of moderate current discharge cycles when the batteries are well-maintained and discharges are limited to ~50%. Essential maintenance requires a four-stage smart charger, temperature compensation of target charging voltages, and periodic watering. Flooded-cell batteries can out-gas potentially hazardous concentrations of hydrogen gas while being charged, so adequate ventilation is a standard safety requirement.

Flooded cell hybrid LAB’s are a kind of battery “jack of all trades but master of none.” These are popular for marine engine starting applications when temperatures do not typically fall below freezing, yet they can still power a trolling motor or smaller marine or RV-type “house loads.”

Give Inverter Service Center a call at 615-285-1734. We’ll help you find a battery solution tailored to your specific needs. Or visit

About the Author – Jim Goodnight – also known as “crewzer” — is a retired solar industry application engineer, product manager, and forum moderator and has previously written for Home Power and Solar Professional magazines.