What is an Amp Hour Meter?(And why the heck do we need it anyway?)

"FEW BATTERIES DIE A NATURAL DEATH...MOST ARE

MURDERED"

----Unknown Industry Representative Source: Sunelco Planning Guide

• With proper care, quality batteries that are sized correctly for your application will last for years. 

• If abused, an expensive battery bank may last only months.

• Taking out too much power without recharging is what kills most batteries. 

• Also, batteries that are low will freeze easily, while a fully-charged battery is good to at least 30 below zero.

• "Deep-cycle" batteries are designed to resist damage from repeated deep discharges (50% to 80% of capacity used up)...but will still last significantly longer if discharged by only 20%

3 Types of Battery Metering3 Types of Battery Metering1.1. VoltageVoltage Cheapest but least accurate.Cheapest but least accurate. Measure DC voltage across the main positiveMeasure DC voltage across the main positive

and negative terminals (where the inverterand negative terminals (where the inverter

and/or solar panels are connected to the batteries). and/or solar panels are connected to the batteries). As batteries age, the voltage reading gradually lowersAs batteries age, the voltage reading gradually lowers

2.2. Specific GravitySpecific Gravity• Accurate, but messyAccurate, but messy• You'll need a good battery hydrometer--it will look like a foot long You'll need a good battery hydrometer--it will look like a foot long

glass turkey baster with a glass float and thermometer inside.glass turkey baster with a glass float and thermometer inside. • Open up one cell on each battery and suck out enough acid to float Open up one cell on each battery and suck out enough acid to float

the floatthe float (Wear goggles and rubber gloves!  Keep baking soda and water handy in case you spill!)(Wear goggles and rubber gloves!  Keep baking soda and water handy in case you spill!)

3 Types of Battery Metering3 Types of Battery Metering

1.1. Amp Hour MeterAmp Hour Meter• Measures the flow of current into and out of the Measures the flow of current into and out of the

batterybattery

• As you use power, the meter counts how many As you use power, the meter counts how many amp hours are used. amp hours are used.

• As the battery is charged, the meter goes As the battery is charged, the meter goes backwards, toward zero. backwards, toward zero.

3 Types of Battery Metering3 Types of Battery Metering

1.1. Amp Hour MeterAmp Hour Meter• Measures the flow of current into and out of the Measures the flow of current into and out of the

batterybattery

• As you use power, the meter counts how many As you use power, the meter counts how many amp hours are used. amp hours are used.

• As the battery is charged, the meter goes As the battery is charged, the meter goes backwards, toward zero. backwards, toward zero.

Think an Amp Hour Meter as Think an Amp Hour Meter as a fuel gauge for your battery banka fuel gauge for your battery bank

Think an Amp Hour Meter as Think an Amp Hour Meter as a fuel gauge for your battery banka fuel gauge for your battery bank

The meter consists of a wooden back, a long wooden needle(14" long), which pivots on  a nail.  To the bottom of the

long wooden needle is a surplus computer hard drive magnet glued on

with super-glue.  You can get the magnet out of most computer hard drives, or...we

sell them, between $1 and $12, depending upon the scale of meter you

have in mind. 

A SIMPLE AMMETER

Here is a simple way to make a reliable, safe ammeter for ... ?  I use mine to monitor power coming into/out of my batteries.  Undoubtedly one could make many modifications; it would not be too difficult to convert this to a full function multi-meter.  Mine shows DC amps, plus or minus 15.  This meter is simple, and reliable enough to serve many applications.  With just a little work, it could be a fine addition to any shop, or living room.

http://www.otherpower.com/otherpower_experiments_ammeter.html

Tri-Metric 2020 Battery Monitor Amp-Hour Meter

• For 12-24v systems (48v with adapter)

• Reads volts, amps, and amp/hours on an LED display

• Can also display “percent full”• LED light flashes when batteries are

fully charged• LED light for when batteries have

very low charge• Records voltage history• $175-$189 ($30 adapter)

Trace TM-500 Amp Hour Meter

• For 12-24v systems (48v with adapter)• Reads volts, amps, and amp/hours on an LED display• Easy installation with custom shunt cable• Provides estimated battery life information• Shows days since full• Highest and lowest voltages• $195 - $250 ($40 adapter)

Xantrex Link 10 • For 12-24v systems• Scrolls through Volts, Amps, Amp-hours / kilowatt-hours

and Time Remaining w/ multi-color bar graph• Easy installation with custom shunt cable• Provides estimated battery life information• Shows days since full• Highest and lowest voltages• Reports kilo-watt hour consumption• “Sleep” mode• $250 with shunt $210 w/o

WHY??

• Maximize the life of your batteries

• $200 compared to replacing a quality battery bank is cheap.

• You can tell the condition of your batteries at a glance

• You wouldn’t drive a car long distances w/o a fuel gauge, now would you?