Tenergy 12v 4200mah NIMH Testing

[icecube57]

I bought some 12v 4.2AH NIMH Packs for about $20 shipped. These come from All-Battery. (They were actually purchased on an Ebay Auction)
http://www.all-battery.com/sidebysi...enimhbatterypackmoduleswithtwoconnectors.aspx

Ive exercised 1 pack about 5 times. My data goes as follows.
These cells are rated at 4.2AH and 40A/10C discharge.

I started at 13.82v fresh off the charger.
Ended at 10.49v
I peaked at 4A on discharge
I discharged 2.45AH before hitting 10.5v
30WH was discharged.
I discharged the battery at 3.6A (using an inverter with a tower fan on high speed)
That was at .85C discharge
I discharged through my Watts Up Meter.

When i charged the pack it was charging at 1.7-1.8A peaked at 14.8v and it put 2.8AH into the pack.


My calculations im getting 60-65% of the rated capacity.

My charger is a burp style charger. It charges for 5-10seconds at 1.8A and it does a 10% pulse discharge for a faction of a sec. My meter was bouncing back and forth. This charger also has a temp prob so it goes by the Delta V and Temp. I tried to charge exposed and covered to see if it could detect Delta V or the temperature better. Exposed with rubberband holding probe on pack took a while longer to charge. Insulated it hit the Temperature threshold quicker and charged at a lower voltage.

The packs are charging up to 14.8v before terminating charge and they float charge at about 13.8.

Im doing tests on another pack with another charger that CC CV that still does the discharge pulse but doesnt show on my volt meter like it does with the other pack. Im also parallel charging (using two chargers on one pack). So the new data will show a charge rate of 3.5A which is about .7C. These chargers dont have a temp probe and they terminate charge solely on Delta V -5mv.

 

[icecube57]

I bought some 12v 4.2AH NIMH Packs for about $20 shipped. These come from All-Battery. (They were actually purchased on an Ebay Auction)
http://www.all-battery.com/sidebysi...enimhbatterypackmoduleswithtwoconnectors.aspx

Ive exercised 1 pack about 5 times. My data goes as follows.
These cells are rated at 4.2AH and 40A/10C discharge.

I started at 13.82v fresh off the charger.
Ended at 10.49v
I peaked at 4A on discharge
I discharged 2.45AH before hitting 10.5v
30WH was discharged.
I discharged the battery at 3.6A (using an inverter with a tower fan on high speed)
That was at .85C discharge
I discharged through my Watts Up Meter.

When i charged the pack it was charging at 1.7-1.8A peaked at 14.8v and it put 2.8AH into the pack.


My calculations im getting 60-65% of the rated capacity.

My charger is a burp style charger. It charges for 5-10seconds at 1.8A and it does a 10% pulse discharge for a faction of a sec. My meter was bouncing back and forth. This charger also has a temp prob so it goes by the Delta V and Temp. I tried to charge exposed and covered to see if it could detect Delta V or the temperature better. Exposed with rubberband holding probe on pack took a while longer to charge. Insulated it hit the Temperature threshold quicker and charged at a lower voltage.

The packs are charging up to 14.8v before terminating charge and they float charge at about 13.8.

Im doing tests on another pack with another charger that CC CV that still does the discharge pulse but doesnt show on my volt meter like it does with the other pack. Im also parallel charging (using two chargers on one pack). So the new data will show a charge rate of 3.5A which is about .7C. These chargers dont have a temp probe and they terminate charge solely on Delta V -5mv.

 

[icecube57]

When fresh off the charger they will not discharge at High Amps until pack is completely cooled down. Translation.... Trying to discharge over 10A straight off the charger it kicks off. The internal thermal breaker will trip and render the pack useless until it cools enouh to use. sometimes a gentle pop on the sensor will reset it. I might have to remove this because sometimes its barely luke warm and it trips. Its supposed to be 70C breaker.

Im also finding these packs are useless above 10A. I will have to parallel all 4 together to be able to discharge at 40A and not have a voltage sag from hell. Or trip the breaker. and instead of the 16.8 AH i will probaby only have 10AH usuable out of these packs because they all are coming up at 2.5AH. Maybe at a 0.1C discharge you can get the 4.2Ah but not at 1C.

 

[icecube57]

I paralleled the 4 packs i have to create a supposed 12v 16.8AH pack.

The packs are only good for about 2-maybe 3C individually. which is about 10A roughly
I say that based on my observation that it will maintain above 12v at those discharge rates for about 60% of the discharge curve

I started at 13.8V
I discharged at 15A down to 11v. This gave me 10.5AH
I reduced the current down to 4A. The voltage jumped back up to 12.03v.
I discharged at 4A down to 11v. This gave me 11.6AH
I reduced the current down to 1A. The voltage jumped back up to 11.73v.
I discharged at 1A down to 10.8v. This gave me 12.2AH

Grand total of
12.2AH
146wh
LV of 10.8
Peak Amps Drawn 17.8A
Peak Watts Drawn 219w



10.5AH was actually usable at a decent discharge rate.
You can limp home on the last usuable 1AH at 4-5A.
Anything past 11.5AH in this configuration isnt worth using because of the voltage sag.

 

[icecube57]

I paralleled the 4 packs i have to create a supposed 12v 16.8AH pack.

The packs are only good for about 2-maybe 3C individually. which is about 10A roughly
I say that based on my observation that it will maintain above 12v at those discharge rates for about 60% of the discharge curve

I started at 13.8V
I discharged at 15A down to 11v. This gave me 10.5AH
I reduced the current down to 4A. The voltage jumped back up to 12.03v.
I discharged at 4A down to 11v. This gave me 11.6AH
I reduced the current down to 1A. The voltage jumped back up to 11.73v.
I discharged at 1A down to 10.8v. This gave me 12.2AH

Grand total of
12.2AH
146wh
LV of 10.8
Peak Amps Drawn 17.8A
Peak Watts Drawn 219w



10.5AH was actually usable at a decent discharge rate.
You can limp home on the last usuable 1AH at 4-5A.
Anything past 11.5AH in this configuration isnt worth using because of the voltage sag.

 

[Russell]

Thanks for sharing the results of your testing. I considered using these packs a while back but now I'm glad I didn't. Your data shows they certainly don't deliver the goods and while they are cheap they become a hassle once you cable up enough in parallel and series to meet the power requirements of an E-bike.

For a robust, cheap and easy to use battery pack it's hard to beat Bosch Fatpacks!

-R

 

[icecube57]

Going to try and do a 30-40A discharge if i can find a big enough load without trippinh my inverter. They can probably give 20A a piece maybe 30 but not at 12v they will probably sag around 10.5v to 11v on individual packs. My inverter doesnt like doing high loads at low voltages thats why i cant do a true indivitual pack test unless i build a lamp rig.. But with the packs all in parallel It can sustain the voltage higher and longer for my inverter . I actually powered my computer and a tower fan for 45 minutes at a 15A draw. Couldnt get the monitor into the equation. I can power it but sometimes i cant handle the surge..... Older 21inch CRT... funny it can power a 27 inch CRT TV fine... Cant do much with 400w inverter. Its supposed to pull 30-40A at full load. We will see.

Currently Im gang raping the pack on the charger. I have 4 1.8A chargers. Its putting out about 7.2A total..... and im charging in parallel. OMG !!! YOU SHOULDNT DO THIS!!!!!The packs have those Thermal breakers that will stop the charge current for the whole pack on both terminals(charge and discharge plugs) if they get to hot. And the chargers have thermalcouples to sense the rise in temperature. Ill keep an eye on voltage. One it hits a certail level Ill kick the switch down to a lower setting unless the charger does it for me.

Each pack has their own individual charging leads and discharging leads. The chargers are plugged to each pack individual charging lead... but the discharging leads are still connectd in parallel. With the breaker in all 4 packs. I really cant over charge them.

 

[icecube57]

Got finished charging my pack. All chargers terminated within a few minutes of each other. The pack was quite warm. I put it in front of a fan for a few minutes. I started discharging at 25-30A. It was taking it like a champ holding at 11.75v. I think its acceptable. Unfortunately i didnt let them sit on infont of the fan long enough. Internal breaker tripped after 10 minutes. Will recharge and try again.

 

[icecube57]

Bad Test Data. Deleted Post Contents.

 

[icecube57]

Loads were taken using a Watts Up meter and a Black and Decker 400W inverter. The test results have different cut off voltages because when the inverter hits a certain voltage it alarms for you to reduce the load. When I reduce the load I can continue to discharge.

My last results were bad. The battery did not fully charge. I put the battery back on the charger and left over night.

Discharge started at 13.8v

7.3AH delivered at 35-40A continuous before hitting 11.v
Reduced load to 28-30A.
9.5AH delivered at 28-30A continuous before hitting 11v.
Reduced load to 21A.
10.05AH delivered at 21A continuous before hitting 11v.
Reduced load to 17A
10.3AH delivered at 17A continuous before hitting 11v.
Reduced load to 13A.
10.7AH delivered at 13A continuous before hitting 10.6v
Reduced load to 8A.
11AH delivered at 8A continuous before hitting 10.75v.
Reduced load to 5.55A.
11.2AH delivered at 5.55A continuous before hitting 10.86v.
Reduced load to 4A.
11.3A delivered at 4A continuous before hitting 10.5v
Reduced load to 1A.
12AH delivered at 1A continuous before hitting 10.59