BATTERY TESTING FLOODED LEAD ACID

When testing batteries in the e-ride vehicle, it is importantto test all batteries. Proper performance of the vehicle depends on all batteriesbeing in good condition. Testing will determine if one (or more) of the batteriesneeds to be replaced.

BatteryDischarge Test

A. Thepreferred testing procedure is to use the Lester Electrical 72 Volt Battery DischargeUnit (Model 25680). This instrument puts a known discharge load (75 Amps) on thebattery pack until the battery pack reaches 63volts. A timer incorporated into thedischarger measures the time needed to reach that voltage level. capacity and remaining life can be determined fromthe test results. This item can be purchased from e-ride Industries as part#U5622A. Using the discharger is an easier more accurate method but requiressome up front cost. If you have multiple vehicles we highly recommend you topurchase this 72 volt battery discharger. Perform the test as follows:

1. Firstrefer to discharge unit operating instructions to fully understand the safetyand operation of the unit.

2. Turnoff the main battery disconnect.

3. Removeall access panels to the battery pack. (see section 2.2.1)

4. Hookup the negative cable clamp of the discharger to B- of the battery pack.

5. Hookup the positive cable clamp of the discharger to B+ of the battery pack.

6. Rundischarger as described in the dischargers operating instructions.

7. Whenthe discharger is running its test, randomly test each battery sequentially inthe pack individually with a multi-meter and record the readings. voltage should fall between 8.0 – 7.0 volts. 8.0is fully charged. 7.0 is completely empty. This will help give you an understandingof how each individual battery is performing. 

8. Thedischarger will draw constant amperage of 80 amps. It takes 90-120 chargecycles to achieve full battery capacity. A new seasoned battery pack operating at 80°F (26.7°C)should have 112 AH of capacity. At this load the discharger should run 1 hour24 minuets (84 mins).

9. Ifdischarge times are low, as described in the discharger instructions run thetest a second time right away. The discharger will operate for 3 more minuetswhich gives you enough time to get a final individual battery voltage reading.Compare individual battery voltages recorded. 

The results of the test cansometimes lead to several different conclusions about the battery pack andrequire varied action.  The followinggoes over the results and the conclusions to be drawn from them:

1. Ifdischarge time was 80 minutes or longer the issue is usually not with thebatteries.

2. Ifdischarge times are low, compare individual battery voltages recorded. If anybattery shows a 0.4 volt or greater variance, that battery is bad or nearingthe end of its useful life and should be replaced.  The voltage of a bad battery will drop morerapidly near the end of the discharge than that of a good battery.

3. Ifall batteries are within 0.30 volts of each other, but the discharge time islow, the batteries are approaching the end of their life and the whole set willhave to be replaced.

4. Othervariables that need to be considered in this test is the battery temperatureand Cycle life. If battery temperature is below or above 80°F (26.7°C)the overall capacity will lower or increase but the battery voltage shouldstill not vary 0.30 volts of each other. As for cycle life it takes 90-120charge cycles to fully season the battery pack. Cycle cycles below this canlower the capacity as much as 20%. In other words a new battery pack performsto 80% its rated capacity.

B. Ifthe Lester Battery Discharge Unit is not available, an alternate battery test canbe done using a multimeter to perform a voltage test of each battery. The mostinexpensive way to perform this test is to use the vehicle’s drive system asits load.  Perform the test as follows:

1. Chargethe batteries until the charger shuts off.

2. Removeall access panels to the battery pack. (see section 2.2.1)

3. Makesure you have no loose components in the vehicle that could fall into thebattery tunnel.

4. Itwill help to have two people to perform this test.  One person to drive the vehicle and the otherperson use the multimeter to measure and record the voltage.

5. Itis best to pick a course that is flat and long without many stops.

6. Recordwhat time the test started. 

7. Checkthe battery pack voltage every 10 minutes of driving.  As soon as the battery pack voltage reaches64 volts start measuring and recording each battery to the nearest 0.01 voltuntil battery pack reaches 63 volts which is zero state of charge.  At this point, record the time and the testis complete.

The results of the test cansometimes lead to several different conclusions about the battery pack andrequire varied action.  The followinggoes over the results and the conclusions to be drawn from them:

1. Ifdischarge time was 80 minutes or longer the issue is usually not with thebatteries.

2. Ifdischarge times are low, compare individual battery voltages recorded in step 7above.  If any battery shows a 0.4 voltor greater variance, that battery is bad or nearing the end of its useful lifeand should be replaced.  The voltage of abad battery will drop more rapidly near the end of the discharge than that of agood battery.

3. Ifall batteries are within 0.30 volts of each other, but the discharge time islow, the batteries are approaching the end of their life and the whole set willhave to be replaced.

4. Ittakes 90-120 charge cycles to achieve full battery capacity.  A new seasoned battery pack should have 112AH of capacity.  On flat, even terrain astock vehicle draws about 85 amps per hour at 25 MPH giving you 80 minutes ofdrive time. Totaling 33 miles per charge.

5. Othervariables that need to be considered in this test is the battery temperature,cycle life and amp draw. If battery temperature is below or above 80°F (26.7°C)the overall capacity will lower or increase but the battery voltage should stillnot vary 0.30 volts of each other. As for cycle life it takes 90-120 chargecycles to fully season the battery pack. Cycles below this can lower thecapacity as much as 20%. In other words a new battery pack performs to 80% itsrated capacity. And as for amp draw this requires higher expensive equipment tobe done accurately but what to consider here is if you are on a hilly terrainthe vehicle will draw more lowing your overall run time.

Hydrometer Test

A third option for battery testing isto perform a specific gravity test of the battery electrolyte using ahydrometer. A hydrometer measures the specific gravity.  An increase in the specific gravitycorrelates directly to an increase in battery state of charge.  A fully charged battery should read between1.250 and 1.280 at 80°F.  Never add acid to a battery to obtain ahigher specific gravity.

Performing the hydrometer test

1. Besure the batteries have sufficient water to cover the plates by approximately1/2” and are fully charged prior to beginning the test.  If distilled water must be added, rechargethe batteries before performing the hydrometer test.

2. Flipopen the cover of the battery filling float assembly.  Locate the white plug under the cover andremove it.  These holes should provideenough access to be able to perform all tests.

3. Usinga battery thermometer, record the electrolyte temperature of one of the middlecells.

4. Squeezethe rubber bulb of the hydrometer and insert it into the cell of thebattery.  Slowly release the bulb,drawing the electrolyte into the hydrometer. Fill and drain the hydro meter twoto four times before drawing a sample.

5. Whenthe hydrometer float rises off the bottom, adjust the electrolyte level so thefloat floats freely from the bottom but does not strike the top of the glasstube. Remove the hydrometer from the cell and release the pressure from thebulb.

6. Holdthe hydrometer vertically, ensuring that the float is not contacting the sidesof the barrel.  Hold the hydrometer ateye level and read the scale at the level of the electrolyte.

7. Recordthe reading.

8. Returnthe electrolyte to the cell from which it was taken. Close float cap andreplace the white plug.

9. Repeatsteps 2-8 on all cells.

10. Temperaturecorrect each cell reading. The readings obtained as described above must becorrected for temperature. Temperature correct each cell reading. For each 10°F (5.5°C)above 80°F (26.7°C) add 0.004 to the specific gravity reading.For each 10°F (5.5°C) below 80°F (26.7°C)subtract 0.004 from the specific gravity reading.

11. The specificgravity of all battery cells should be 1.277 + or - 0.007. If low cell readingsexist (see chart below), charge battery and take specific gravity readings again.

12. If specificgravity of any cells remains low after complete charging, battery should be replaced.