Battery Testers

© Brooke Clarke 2007 - 2022

State Of Charge
    Radio Shack 22-080 Household Battery Tester
    ZTS Mini-MBT
    ZTS MBT-1
    TS-183 Mil Dry Battery Tester
    PSM-13 belt carry Mil Radio Battery Tester
    TS-4403 LiSO4 Mil Radio Battery Tester
    TS-23  BA-1574/U Mercury battery Tester
    Drop Test
Capacity Testing
    Coulomb Counting
    Filament Flashlight Bulb
    Constant Current
    Constant Power
    Electronic Load
    Watt's Up
    Maha 777Plus
    Maha MH-C9000
     iMAX B6 LCD Screen Digital Lipo NiMh Battery Balance Charger
     1.5v~12v Battery Capacity Meter discharge Tester 3.7v 18650 lithium lead-acid
    BF-1L Battery Fixture (Single Cell)
    Foxwell BT-705 Battery Load Tester (see Brooke's Vehicles web page)
Internal Resistance
    EVB ESR/Low Ohms Meter
    HP 4328A Milliohm Meter
    ESR-Cap meter
    SM8124 Battery Impedance Meter
    SM8124A Battery Impedance Meter
Dynamic Resistance
Shelf Life 
    Cadex C7200
Flash Amps


There are a number of reasons why you might want to test the capacity of a battery.  For household type batteries it's good to know if it's the battery that has died or the device holding the battery.  When working with rechargeable batteries it's good to know the state of charge, i.e. what's the capacity.

I've found a number of cases lately where the Radio Shack battery tester shows in the middle of the green, yet the battery is not powering the device.

State of Charge

These testers estimate the remaining life of a battery.  For Carbon Zinc and to a lesser extent Alkaline this can be done by measuring the battery voltage while a light load is applied.  If the proper load is chosen for a given battery capacity the loaded battery voltage works well as an indicator of remaining life.  The idea is to determine the state of charge using as little of the batteries capacity as possible.

HP 66311A Mobil Communications DC Source

This test instrument was specifically designed to measure the power consumed by battery operated devices, like cell phones, and to measure the associated battery and battery charger.

Radio Shack 22-080 Hand Held Battery Tester

Radio Shack 22-080 Battery TesterAug 2007 - Added test jack table to TS-183 web page so that the Radio Shack load resistors could be compared to the TS-183 load resistors.  The Radio Shack tester showed a 9 volt battery as good yet the battery would not work in the postal scale.  The TS-183B showed the resistor as bad after abut 5 to 10 seconds.  There's a 100% difference in the load resistors for this voltage.  Need to check the others.

In addition to the test leads this battery tester also has metal contacts for a 9 volt battery on the front panel, the negative contact and be used on the bottom of AA, C, D battery and the red lead to make testing easier.  On the right side is a slot for button cells and part of the front panel can be depressed to make contact to them.  For most common batteries I have used this tester, but now am no longer as confident in it's abilities.
Range RS
Load R
Load R
1.5v 1 ma button cell

3v 1m Lithium cell

AAA & N 50 ma

AA  &  C  &  D  150 ma
Photo 6v

9 volt
12v 1k2

15v 1k5

22.5v 2k3


ZTS MBT Mutiple Battery TesterSince the above Radio Shack tester does not work very well I've been on the lookout for an improved tester.  ZTS makes a number of handheld battery testers and the Mini-MBT (Multiple Battery Tester) is what got.  They have a utility and a design patent.

6823274 Apparatus and method for testing remaining capacity of a battery, Nov 23, 2004, ZTS, 702/63 ; 320/125; 320/136; 702/64; 702/65; 702/79
uses voltage at end of resistor load pulse.  D515444 Battery Tester - packaging for the 6823274.

When a battery is connected it's immediately under load and after a few seconds the loaded voltage is read.  The capacity is based on the loaded voltage at the end of the test time.   The patent has data on the load resistance for 8 different battery types as well as capacity information in 20% steps for 3 & 6 Volt versions of the CR123 photo battery and for the 1.5 volt alkaline terminal.

The four battery types that the MBT will test are:
Cell Type
1.2 volt
AA, AAA, C, D, N
CR123, CR2, CRV3
I checked the same battery that the Radio Shack tester showed in the green and this tester either shows it as bad or on the second try it failed to start the test, meaning it's dead.
Also checked some CR123 cells that have been here for years.  They test at different levels.  I haven't made any controlled discharge tests to see how accurate this tester is, but at a first look I like it.
ZTS Mini-MBT InsideThe Mini tester uses a socketed 18 pin micro controller without a seperate MUX IC and without an external crystal.  The circuit board is soldered to the positive and negative battery terminals and so can not easily be removed.  There's a 4 post 0.1" header for testing the unit, but it's between the PCB and back cover so is not accessible after the front cover is removed. 

Instead of using a switch like on the Radio Shack tester, this one uses 4 different positive battery terminals and a common negative test lead.  There's a groove around the tester to hold the lead and a pocket for the short probe body on the left side not shown in the photo.  The On button is on the right side.

There are two lower priced ($30) models this one (Mini-MBT) and the MINI-MBT9R.  The difference is that on this one the lower left terminal is for the CR123 Li-MnO2 primary battery and on the other one it's for a Rechargeable 9 volt battery.  I specifically wanted to try the CR123 battery test since I use these in some of my products (5BA, 90BA Battery Adapters).

The TS-183 works the same way.  You pick the test jack to match the battery instead of using switches.  The load is permanently associated with the jacks.  For example on the TS-183 jacks 1, 2, 3, & 4 are for single cell batteries and 1.40 V is the 80% indicator.   Jack 3 is for a "D" Zinc Carbon battery and uses a 6 Ohm load.  The ZTS tester is using a 9.1 Ohm for alkaline cells with a 80% voltage of 1.41 V.  ZTS could eliminate the whole relay circuit and thus lower the cost of the tester since one of the connections to the cell under test is by the probe.  That's to say whoever is testing the battery has to hold the probe on the cell   If there was a socket holding the cell then the relay has some merit, but in this case it's not likely someone will "forget" and keep holding the probe on the cell for an extra hour or more.

There are some  aspects that could be improved. 
These are nit picks.  This is be far the best battery tester I have.
They make more expensive testers that can test a longer list of batteries.


U.S. Patent 6823274 shows on the front panel.

ZTS MBT-1 Battery Tester

Runs on 4 AA batteries.
3.6 V Lithium-Ion
1.5V Button Cell

1.2 V NiMH
1.5 V AA Lithium
3V Lithium Button
6 V 28 Series
3V Lithium
1.5 V Alkaline
12 V Alkaline
9 Volt Alkaline


Army dry battery tester.  Works by measuring loaded voltage.


The set can be carried on a belt and tests radio batteries, Vietnam era.  Uses high current load to activate Magnesium batteries.


LS 91 & LS 94 State of Charge Tester for LiSO4 primary batteries BA-5590/U, BA-5598/U and BA-5588
4725784  Method and apparatus for determining the state-of-charge of batteries particularly Lithium batteries, Feb 16, 1988, 324/427 ; 320/149; 320/150; 320/162; 340/636.15
Uses pulse loading and voltages measured at various times in relation to the load pulse as well as temperature correction.  Capacity depends on manufacturer as well as model.


Tests the BA-1574/U Mercury battery used in the SDU-5/E Emergency Survival Strobe Light and the flash rate of the strobe.
BT-2 - Tests BA-1568/U as used in the PRC-90 Survival Beacon Radio and others, BA-1113/U used on the URC-64 Survival Radio, the K308A battery  used on the RT-10 Survival Radio, and the  BA-1574/U used on the SDU-5/E Emergency Survival Strobe Light.

Drop Test

The idea is to drop a AA battery with the + end up on a reasonable hard surface.
This may work for other Alkaline cells?
A good battery will make a thud sound, no bounces and may stand up.
A bad battery will sound metallic, bounce and fall over.
How To Test a AA battery, Easiest Way For Any Battery Fast, Easy!
The comment about testing with a volt meter is wrong.  A no load test does not mean anything.
For a meter test to mean something the battery needs to be loaded.  See the TS-183.  Even load testing does not work well on modern batteries.

Capacity Testing

The idea here is to drain the battery using a known load until it's voltage is down to the end voltage and record the delivered Amp hours, or better delivered Watt hours.  Note that when the battery starts the test it's voltage is highere than at the end where the voltage is the pre assigned ending voltage.  So the early amp hours are at a higher voltage than the ending amp hours.  The early Watt hours are higher than the ending Watt hours.  So reporting the run time using a load resistor or constant current source is not as accurate as reporting the delivered Watt hours.

The results for a given battery will be different as a function of the load. 

Coulomb Counting

By measuring the current and the elapsed time the product of them is how many coulombs (Wiki) have flowed.  Most modern rechargeable batteries use coulomb counting to determine State of Charge and that can be translated into remaining run time.

Baiway BW-TF01N Ver 6

Fig 1
Baiway BW-TF10N
Fig 2
Baiway BW-TF10N

This is a stand alone coulomb counting circuit available on eBay lu_cytime208 with a title of "Capacity Tester Indicator for 0V-30V Lithium LiPo / LiIon Battery LCD Display" for about $30. 
It can be connected into either a discharge circuit to measure battery output or into a charging circuit to see how much charge in put into the battery.  Note that you always put more charge into a battery than you can extract.  That's to say the efficiency is always less than 100%.
This unit has no provision to turn the load on or off.  It is not a load tester nor is it a charger.  The Set Voff voltage is used to control when the TF01N goes into sleep mode.  The idea is to build this coulomb counter into a battery pack so it's state of charge can be monitored and to minimize the power used by the TF10N.  There is an internal current shunt that can be used for currents up to 3 Amps and after that an external shunt can be used up to 50 Amps.
It has no provision for an external power source, but rather runs on the battery pack it's connected to and that pack needs to have a voltage of more than 8 volts (up to 50 Volts).


A fixed resistor is the load.  The load current decreases as the battery voltage goes down. 

QS-906 eBay title: .5v~12v Battery Capacity Meter discharge Tester 3.7v 18650 lithium lead-acid

14 Sep 2016
This unit came from the same eBay seller as the first non functional one,
but this one has a resistor marked R020
 instead of a resistor marked R200 like the first (improperly assembled) unit.

See below for battery fixture.
QS-906 eBay
                    title: .5v~12v Battery Capacity Meter discharge
                    Tester 3.7v 18650 lithium lead-acid
Discharging an eneloop.
More later .. . .
2.65 AH vs. label capacity of 2.45 AH.
roughly works without calibrating.
Fig 5
QS-906 eBay
                    title: .5v~12v Battery Capacity Meter discharge
                    Tester 3.7v 18650 lithium lead-acid
Testing 18650 battery:
15 Ohm 5W resistor (4.1v / 15 Ohm = 273 mA) close to the 300 mA spec
for this Li-Ion battery rated at 1500 mAh,
which tests between 1450 & 1470 mAh (0.777 mAh shown)
K&J Magnetics parts to make connection to battery use 6-32 flat head screws.
0.625" dia (RA22CS-P) and 0.25" dia (R422CS-P)

This is also known as a ZB2L3 ZHIYU Battery Capacity Tester External Load Discharge Capacity Test (I have one of these on order 29 AUG 2016)
The current sense resistor can clearly be seen with matching markings on the PCB and resistor of R020.


This is a battery capacity tester that uses an external resistor as the load to drain the battery.  The load resistor has nothing to do with the device calibration.  Once properly calibrated the load resistor can be changed and the readings will still be correct.

Load Resistors

The load should never exceed 20 Volts or 6 Amps because of the MOSFET switch. The MOSFETs are in parallel so the current can be higher, but I doubt as high as 12 Amps.
There may be a firmware limit of 15 Volts or 3.1 Amps.
The current through the resistor will vary from a maximum value set by the fully charged battery voltage and resistance.
For example an eneloop AA battery may start out at 1.4 Volts with a 7.5 Ohm resistor for a current of 0.187 Amps.
The power dissipated in the resistor is V * I or 1.4 V * 0.187 A = 0.261 Watts.
Since the supplied resistor is rated for 5 Watts this is no problem, but for more powerful batteries a resistor with a higher power rating may be required.

Circuit Description

The tester uses a micro controller mounted under the 4-digit 7-Segment LED display.
An 8205s (pdf) Dual MOSFET each FET  speced: 28 mOhms RDSon with a max rating of 20V or 6 Amps are connected in parallel and switch the load to battery positive (see Fig 2). 
The battery current is sensed by R2 (0.2 Ohms) between the negative battery terminal and ground. 
The battery voltage is sensed by (a guess - hidden circuit under display) a voltage divider R3 & R4.
Just above the Ah LED is a 0.1" pitch 4-hole pattern that's probably for in circuit programming of the uC. 
The LM1117 (TI) Low Dropout voltage regulator is set for a nominal 3.3 Volt output (3.29 actual).
The uC is hidden so don't know make or model.

Fig 2 Input Schematic
                    Battery Tester Input Schematic

Internal connection between R (J1-4)and +In (J1-3).

Guessing at R3, R4 Voltage divider.

R2 is the battery current sense resistor.

Q1 & Q2 in parallel to switch load to ground.

For all the parts except R2 the marking on the part
matches the nomenclature. 
But for R2 the PCB is marked: R020
             and the part is marked: R200
Photo here shows a resistor marked R020.


Battery and Resistor disconnected.

Step 1.

Display shows: 0A0u (zero Amps and zero Volts), Q1 & Q2 are open so there is no load on the battery.  The battery voltage drives the microcontroller ADC.
Battery removed and either left open or shorted.  Which works best is TBD
When OK is pressed the zero calibration for both battery voltage and current is stored (but not saved)

Step 2.

Display shows: 100u (10.0 Volts). Q1 & Q2 are open so no load on battery or heat in resistor.
Remove battery.
External 10.0 Volt power supply to battery +In and -In terminals.
When OK is pressed the voltage at ADC V-In is measured and a ratio stored to get to 10 Volts.

Step 3.
Display shows: 200A (2.00 Amps). Q1 and Q2 are turned on. So if resistor installed it will heat because of the internal connection between R (J1-4) and+In  (J1-3).  But the resistor can be removed during calibration to avoid overheating it.
Remove battery.
Connect positive source of 2.00 Amps to -In (J1-2 in Fig 2 above) and the ground to J1-1 (bottom R).
When OK is pressed the voltage drop across R2 is measured and stored.
Note the circuit impedance is a few tenths of an Ohm so the current source does not need to have a high voltage compliance, like was needed if you mistakenly try to calibrate using the battery terminals for this step.

Step 4.
When OK is pressed the above values are checked for reasonableness (how is a mystery) and if they seem OK they are saved in EEPROM in the uC.

Note this cal only needs to be done one time.


With the load resistor and battery connected power up the QS-906.
Press (+) or (-) to see the termination voltage and then press (+) and/or (-) to set the termination voltage.
Then press OK to start the test.
The first Ah display should be zero.
The first A display should be the battery starting voltage divided by the load resistor value.
The first V display should be the battery fully charged voltage minus a little for the effect of the load because of internal resistance.

Error Codes

Err1: the battery voltage higher than 15V
Err2: the battery voltage is lower than the termination voltage setting.
Err3: the battery is unable to support the load current or of the test lead resistance is too large.
Err4: the current is too large (current is more than 3.1A.

Example (29 Aug 2016)

eneloop AA cell after calibration using short in step 1 as above.  Results before test finished:
Ah:  3.076 [ended at 7.761 a little more than 3X the actual value]
A:  0.665 (current still reads 4.01 x too high)
V:  1.24 (DMM: 1.277 V, implies a current of 1.277 / (7.5 + 0.2) = 0.1658 A
Still not reading correctly.  Maybe because of the R2 value problem (PCB: R020, resistor R200).


A way to fix the current calibration is to change the current used for the cal and tweaking the value to get the current to read correctly.

I'd like to use this to test BB-2590 military batteries that are 4 cell Li-Ion, i.e. fully charged at 16.8 Volts, so a bit above the 15 V firmware limit.
So . . . . by cheating on the voltage calibration by say 17 V / 15 V and after finding the correct current for a normal cal change that by 15V / 17V.
This would require modifying the cutoff voltage by 17/15, but then the Ah would read correct.

Fig 3 Checking Current
Power Supply on + & - battery terminals
Note PS= 4.50 V, measure 3.94 V because
of resistance of test leads. 
QS-906 eBay
                    title: .5v~12v Battery Capacity Meter discharge
                    Tester 3.7v 18650 lithium lead-acid
Fig 4 Checking Voltage
Load resistor disconnected.
PS on + and - battery terminals.
PS= 13.76 Volts (just under err1 voltage), measure= 13.98 V.
Note:  err1 only happens when tester in run mode.
In startup mode I increased input to 18 Volts and the tester
displayed it without any error message.
QS-906 eBay
                    title: .5v~12v Battery Capacity Meter discharge
                    Tester 3.7v 18650 lithium lead-acid

29 Aug 2016 resolved Prior Problems - only read for background
Under $5 including shipping from Hong Kong.  It does NOT work as it should, needs updated firmware.

Fig 1  After OAOu:Short, 100u:10V, 200A:2A Cal
actual current is 1.37V/7.5Ohm = 0.182A, Display current is 0.659Amp, Why?
QS-906 eBay
                        title: .5v~12v Battery Capacity Meter discharge


An external 5W 7.5 Ohm resistor is switched to the battery when the OK button is pressed and switched off when the battery voltage drops below the limit voltage indicated by Pnnnn.
After the battery is connected press + or - to change the value of P and when correct press OK to start the test.
YouTube video of QS-906 circuit running.

Maybe calibrated for Voltage (10V ref) and Current (2A ref)  So the tester can calculate the current given the loaded voltage.  If the test leads have too much resistance:
Err3: the battery is unable to withstand the load discharge current resistance is too large or line.

I have not yet figured out why some of the error codes appear or how to do the Calibration.  If you know more contact me.

The tester has NOT been calibrated and the default cal is way off.
When testing a Panasonic eneloop pro AA battery with the 7.5 Ohm load resistor the tester shows: 1.69 A at 1.28 V equivalent to a resistance of 0.757 Ohm load.  So way out of cal.

But when the same battery (fully charged) reads 1.409 V open circuit and 1.403 V with the 7.5 Ohm load applied.  Actual current is V / R = 1.403 / 7.5 = 0.187 A = 187 mA

The battery internal resistance is (1.409 - 1.403) / 187 mA = 0.032 Ohms.
Short current current might be = 1.403 / 0.031 = 43 Amps (but not likely).
Tried cal (holding down all 3 buttons then connecting power.  After start up displays: ---- (indicator for Calibration mode), 0.004 (maybe offset voltage) , OAOu (maybe zero Amps & zero Volts)
when OK is pressed the display changes to: 10.0u when OK pressed again display is 200A, and when OK pressed again reverts back to Ah -> A -> V -> Ah cycle.  Doing the cal requires a power supply that can deliver both 10.00 Volts and 2.00 Amps.
But after trying to do the cal first with 10V and 1A and twice trying 10V and 2A the cal fails, i.e. when testing the eneloop shows 1.8 Amps, way too high.
Also tried with current in negative direction, but still get 1.8 Amps on the eneloop, not the 0.187A is should be.  Maybe some factor of 10 error?

Note: with the supplied 5W 7.5Ohm resistor when the input is 10 Volts the power in the resistor is 13.3 Watts, and when 2.0 Amps are flowing the voltage drop across the resistor is 15.0 (the max rated input voltage) and the power in the resistor is 30 Watts.
This means the calibration must be done very quickly.

Maybe the Ah display is showing 10X the actual capacity.  Will test an eneloop to completion to see if it comes our near 2.4 Ah X10 = 24 Ah.
The QS-906 shows 1.36 Volts and the DMM reads 1.348 Volts on the screw terminals.  Shows 1.741 Amps Voltage drop across the 7.45 Ohm resistor is 1.308 for a current of 1.308 / 7.5 = 0.174 Amps

Note current is reading 10.0057 X higher than actual, so it looks like a 10x error.
Next to see how the battery capacity compares with the MH-C9000 (tested at 1.0 Amp load, but can be rerun at  something closer to 0.174A.)
If 2.4 Ah capacity and 0.174A load then  13.8 Hours to discharge.  About 12:30 now.
About 1:00, was not watching, the mode indicator LED is flashing for Ah, A and V instead on being on steady.  Displays: 1.003 Ah, 1.692A (actually 0.1692A) and 1.31 V (cutoff set to 1.20 Volts).  Do not understand whey flashing.  Will let run longer to see if V display (and DMM) go down to 1.2 V.  Load resistor has 1.264V voltage drop ( 0.168A) so still connected.

At about 11:00 pm the voltage was 1.24 V so not done.  Next morning very fast flashing and the capacity shows at 19.71 Ah.  Pressing OK twice shows the voltage as 1.26, i.e. the cell has recovered a little.  Pressing OK some more times to restart testing shows: 0.000 Ah, 1.583 A & 1.23 V.

So, it looks like the reported capacity might be 10x the actual capacity.  Now testing an eneloop at 200mA discharge to see what capacity it has.eneloop has 2480 mAh capacity when discharged at 200 mA, so the19.71 Ah (divided by 10 = 1.97 Ah is still way off.

Tried calibration:

1. Short, 0A0u -> OK
2. 10 V, 100u -> OK
3. 2 Amps, 200A -> OK
but when fresh eneloop battery installed the displayed current is 0.669 Amps, much higher than the actual .174 Amps (384 % off). 
The next day the display shows:
Ah: 7.125 (clearly much higher than 2.4 the actual capacity)
V: 1.26

Filament Flashlight Bulb

The resistance of the bulb changes in a non linear way with the battery voltage.  The bulb gets dimmer as the battery voltage gets lower.  How dim does the bulb need to get to say the battery is dead?  Kind of a fuzzy feely thing maybe not the best capacity test method.

Constant Current

When a constant current load is used the delivered Watt hours are directly proportional to run time.  This is the most constant load type. 

Constant Power

Switching Mode Power Supplies, like used in most modern battery powered devices consume what's pretty close to a constant power in Watts.  This means at higher battery voltages they draw smaller currents than when fed lower battery voltages.  This is the oppsite of the resistor load.

Electronic Load

A transistor or other device can have it's resistance varied electronically and so acting as a programmable load.  The mode of operation can be as simple as looking like a resistor, or a more useful mode looking like a constant current.

Amrel EL1132 Electronic Load

This is a bench top electronic load test instrument that can be set to look like a constant resistance, current, power or voltage load.  By using a computer to control the load and read back the battery voltage and current almost any test sequence can be accomplished.  There is a low voltage limitation of  2.5 Volts.

ZPB30A1 "Constant Current Electronic Load 9.99A 60W 30V Battery Discharge Capacity Tester"

The quoted title of this paragraph is the same as the eBay title for this made in China tester.  eBay seller ayanhu81 (about $20).  The same seller also has a "Four Wire Battery Holder Battery Resistance Test for 18650 26650" that works with the capacity tester.  See a nicer BF-1L 4-wire battery holder below.
Note this unit has no charging capability, it's only a constant current load or capacity tester.  Can also be used to test sources like wall warts, power banks, &Etc.
Technical Review -
Youku video (Mandarin): Use as Constant Current Load -
Youku video (Mandarin): Use as Battery Capacity Tester -

Fig 1
                  Constant Current Electronic Load 9.99A 60W 30V Battery
                  Discharge Capacity Tester
Input power: 12 VDC <= 0.5 (0.1 typ)
DC power connector: 5.5 x 2.1 mm.
Power up display: 03.0u Volts & 0.21 Amps
Fig 2 as received was in Constant Current Load mode (Fun 1)
                  Constant Current Electronic Load 9.99A 60W 30V Battery
                  Discharge Capacity Tester

The top display stays fixed on Volts

Before inserting the power plug,
hold down the red button, then plug in power.
Turn knob so that Fun 2 appears, then press knob.
unplug power.

Now unit will come up in Battery Test (Fun 2) mode.

The other parameter that shows up after the Function is the beep mode on or off.
Fig 3 after changing into Fun 2: Battery Capacity mode
                  Constant Current Electronic Load 9.99A 60W 30V Battery
                  Discharge Capacity Tester

1.00 Amp constant current load, 14.4V cutoff

The top display rotates between: Voltage, Ah & Wh . . . .

This battery is a 4S Li-Ion BB-2590 (BT-70791BK1).
Probably 225 Wh, but we'll see.
Note the voltage displayed (16.07) matches what I read with a FLuke 87 DMM (16.07), so for a 1 Amp load and these short wires the IR loss is about zero.
Fig 4 At end of capacity test
                  Constant Current Electronic Load 9.99A 60W 30V Battery
                  Discharge Capacity Tester

Note the State Of Charge bar graph on battery shows 1 bar here and in fig 3 above shows all bars.

Tester reads 6.747 Ah, 15.18V & 102.4 Wh

Test was run with 1.00 Amp load & cutoff @ 14.4V.

Watt's Up

This is a handy gadget that not only measures voltage and current but also has an internal clock so that it can count coulombs.  This allows displaying Amp Hours and Watt  Hours.  It's a natural to have power pole connectors on the input and output.  A battery might be the input and a motor might be the output, or a battery charger might be the input and a battery on the output.  For measuring voltages below maybe 4 volts an external power supply is needed.  There's a 3 male pin connector next to the SOURCE wires where an external battery can be connected to power the Watt's Up when testing below 4 Volts.

wu100v2_user_manual.pdf  (at RC Electronics)

Watts Up
                      Coulomb counter
                        Up with Aux Battery

Watts Up Coulomb counter
Aux battery connected to allow working with voltages below 4.
With test leads shorted there's a reading ov 0.05 volts.
Org : gnd, Red:+9 drawing 5 ma Brn: Reset when grounded.
Aux cable at PowerWerx

Maha 777Plus

Ni-Cad, Ni-MH or Li chemistry charger discharger with LCD readout of parameters.  Does packs.

Maha MH-C9000

Intended for Ni-MH AA or AAA cells.  Only tests single cells, not packs.  Four independent channels and can do different things to each channel.


Multipurpose Charger Discharger Cycler for a number of chemistries with plenty of adjustments.  One battery at a time.  Can do packs.

iMAX B6 LCD Screen Digital Lipo NiMh Battery Balance Charger

1.5v~12v Battery Capacity Meter discharge Tester 3.7v 18650 lithium lead-acid

BF-1L Battery Fixture (Single Cell)

This is fixture was laser cut from clear acrylic and the saw tooth bed has markings for 34, 44, 49 & 65mm long cells.  It is a Kelvin fixture with separate wires for forcing current and sensing voltage.  The negative terminals are spring loaded. Fastech BF-1L

BF-1L battery Fixture with standard AA cell on 44mm setting
BF-1L battery
                  Fixture with standard AA cell on 44mm setting
BF-1L battery Fixture w/o a battery
BF-1L battery
                  Fixture with standard AA cell on 44mm setting

Internal Resistance

Any resistance inside a battery will generate heat during charge or discharge.  It also limits the maximum current a battery can supply.  Classically secondary batteries, like lead acid, are used for high current applications because of their very low internal resistance.  I tried to measure the internal resistance of a Leclanché Battery with a Fluke 87 DMM and burned out the internal fuse because it could supply much more current than I expected.

This is very similar to, if not identical to, to concept of ESR (Wiki Equivalent Series Resistance) in capacitors.  A high ESR means that the capacitor can not do as good a job as another capacitor with a much lower ESR.

The use of an amp meter to "Flash Amp" test No. 6 dry cells is based on looking for both charge and low internal resistance.


Table of Maximum Available Current for RC rechargeable battery packs nominally 7.2 Volts.
Internal Resistance is approximately Nominal Voltage / Flash Amps - "D" cell 1.5 V / 13A = 0.12 Ohms (but the resistance of the Flash Amp meter needs to be subtracted.)
Ryobi Tire Inflator Battery Internal Resistance - both are "18 V, 4.0 AH";
Not much different?

PBP005 20.7 0.0451 459
"Hi Performance"
0.0432 474
Black & Decker LST522 String Trimmer - these are all standard batteries, comparing 2.5 AH with 4.0 AH batteries.

SM8124 (20R) Battery Impedance Meter

SM8124 Internal
            Battery Resistance Tester
I let the smoke out of my ESR-Cap meter when trying to measure the internal resistance of some 7.2 Volt RC batteries, so found this unit from eBay seller hkwisefield (eBay search for Internal Battery Resistance Tester).

The top switch is Off-Ohms-Volts and the bottom switch is 100V/200mOhms-20V/2 Ohms- 2V/20 Ohms.
There are two wires to each test probe (i.e. Kelvin connections) to cancel test lead resistance.  But only a single terminal.
The test signal is about 1 kHz at more than 1 VAC.
By using an AC test signal the meter can use AC coupling for the resistance measurement keeping DC out of the test circuitry.
The AC test signal also has the advantage of not being influenced by voltages caused by thermal differences at metal junctions.

To replace the 9V battery peal the rubber case from the top side just enough to get to the battery compartment.

PS this meter is also called "20R" and there is a very similar meter called SM8124 that's for measuring UVA and UVB light.

For a practical application see testing RC Car 7.2 Volt battery sticks for Maximum Current by measuring battery resistance.

SM8124A Battery Impedance Meter

The "A" version adds Kelvin connections to replace the single terminal connection used on the SM8124 version.  So now each probe has two spring loaded terminals.  This should improve the accuracy by eliminating the probe to DUT resistance.
Have this on order (Dec 2021, Rcvd: 2022 Jan 5)  in the hope of testing the internal resistance of some tool batteries, like the Riobi and Black & Decker.
eBay title "Battery Resistance Voltmeter Internal Impedance Meter LCD Rechargeable SM8124A" from seller tangzhimin1008.
Came in a hard carry case which I like better than the soft carry case shown in the eBay ad.
Uses a single 9V battery.

Resistance test drive (measured with Fluke 87V DMM)

Fig 1
SM8124A Battery Impedance Meter

EVB ESR/Low Ohms Meter

EVM ESR meter modified with
        no protection diodes, added resistor & switchYou can use one of the hand held capacitance ESR meters to measure the resistance of individual cells and of battery packs.  But first a couple of modifications need to be done.
(1) The two large protection diodes need to be removed from the PCB.  They are located near where the banana jacks are wired.
(2) A SPST normally open push button switch is added near the tip of one of the test leads and in series with the lead.  Across the switch place a 470 ohm resistor.  When the probes are first connected to a live battery the 470 Ohm series resistor pre charges the internal non polarized blocking caps without hitting them with a really fast rise time pulse, thus tending to protect the internal circuitry.

To make a measurement first do the calibration by:
Then to make a measurement:
The meter I'm using from EVB in Portugal, is the same circuit designed by Bob Parker and sold by Dick Smith Electronics  in Australia as a kit.  I saw mention of battery testing at Hints for techs using Bob Parker's ESR meter(kit)...  and an email from Bob suggested the switch and resistor to reduce the likelihood of damage to the meter.

I'll be using it to test the battery packs for my 5590BA Battery Adapter.

HP 4328A Milliohm Meter

I haven't tested the 4328A on a battery but it's my recollection that it's rated for up to 150 Volt batteries.  More modern meters are limited to 42 Volts because of human safety considerations, so there's still demand for the HP 4328A meter for testing between 42 and 150 Volts.

ESR-Cap meter

The ESR-Cap meter can easily measure internal resistance.  See the example table of data.  But the early versions without internal protection circuitry can be damaged if an attempt is made to test a capacitor charged to a very high energy level or connected in reverse polarity.

Dynamic Resistance

This is a concept first patented (3873911) by Champlin for testing lead acid storage batteries.  He choose a square wave test frequency of 100 Hz and measured the battery internal resistance.

Snap-On patented (5773978) an improved version where they used better circuitry to get more sensitivity and resolution.

Snap-On patented (7657386) a Battery Service System that connects to the battery but checks the alternator and starter.

1. System Test
2. Battery Testing & Charging
3. Starter Test
4. Alternator Test
5. Noise Test
6. Multimeter

Shelf Life

New for me Oct. 2007 are the "Ready to Use" rechargeable batteries.  Sanyo eneloop brand in AA Ni-MH format.  Capacity of 1.9 to 2.0 AH.  Testing capacity can be typically done in less than 24 hours, but shelf life may take months or years.  See the eneloop Ready To Use battery web page for the test plan.

self-discharge (Wiki) causes most rechargable batteries to loose charge just sitting.
% / month
15 to 20
2 to 3
Ready to Use Ni-MH

Also see the paragraph on Li-Ion battery maintenance and the associated video.


A battery analyzer has the capability to both charge and discharge a battery and make measurements of it's parameters, so is more than either a battery tester or a battery charger.

Cadex C7200

Cadex C7200 is a 2-bay battery analyzer mainly built for Ni-Cad, Ni-MH, lead-acid but also can do some Li-Ion battery stuff.

The HP 6633A can work in two quadrants and so can both charge and discharge a battery so software could be written to use it as a battery analyzer (or a battery simulator).

YouTube - 6632B battery test software - 6632 is 20 V @ 5 Amps, the 6633 is 50V @ 2 Amps. testing 1850 3 Ah cell.

Christie makes a number of battery analyzers, like TS-3997/U NSN: 6625-01-227-9615.  This appears to the a relabeled CASP/2000 battery tester aimed at Lead-acid and Ni-Cad aircraft batteries.  Not Li chemistries.

Flash Amps

This is the current a battery can source when a load of 10 milli Ohms is applied for 200 milli seconds.  So far the only mechanical relay I've found that can handle 40 Amps (needed for "D", "F" and No. 6 dry cells) with a contact resistance will below 10 milli Ohms  is the one used in car starter motor circuits typically rated for 400 Amps.  Solid state devices have way too much resistance.  A method of getting the required load is to connect just under two feet of 14 AWG copper wire across the terminals.  The problem is only connecting it for 200 milliseconds and then disconnecting.  If left connected longer serious problems with the battery or load may occur.


Back to Brooke's PRC68 home, Products for Sale, Battery, Battery ChargersBattery Patents, Leclanche, No. 6 Battery,   Military InformationPersonal Home page

page created 13 Oct 2007.