DiveDiversions
Contributor
Xtar was kind enough to reach out and offer me some of their new 21700HP – 5000mAh 25A batteries to review. Having had Xtar product and batteries in the past I was happy to accept and do a review on them.
The batteries are 21.5mm (0.846”) by 74.8mm (2.944”) in width and length respectively, and weight 73 grams (2.57 ounces) each, although when I weighed them, they were slightly lighter at 70 grams (2.47 ounces).
The batteries are protected cells that means that they are approximately ~5mm (0.196") longer than unprotected cells. For majority of lights and other common low power portable devices this shouldn’t pose a problem, but for high current devices that typically use unprotected cell this extra length could be an issue.
The nominal Voltage is 3.6volt with a discharge cutoff at 2.5 volt.
And a capacity of 5000mAh with a massive max discharge current draw of 25A! (That’s impressive for a protected cell)
Other details from the Xtar website:
I don’t have the means to test these batteries using a dummy load to test the full stated current delivery of these batteries, but I thought I do something more real life in the way of testing.
What I have set up is the following:
The batteries are connected in series to produce a voltage of 7.2 volts and are connected to a DC-to-DC boost inverter to step up the input voltage to 24 volts. Connected to the inverter is a very high RPM fan (the likes of what you see in a Dyson product, the thing has a very impressive airflow)
The inverter unfortunately has an input current limit peak of 12 Amps but also has a very low input voltage of 4 volts, so it can’t test the full current but can test down to the cutoff voltage.
Specs of the inverter:
Here is a video of the test being performed (4 minutes of riveting viewing
)
And the results from that test
Not sure what happened around the 21:30 minute mark, I suspect that the input voltage to the inverter dropped enough that the inverter dropped the output voltage and thus reduced the current draw.
It could have also been a thermal protection as the inverter is only rated for 12 Amps for a short duration (21 minutes is short, isn’t it?
), saying that, the inverter wasn’t overly hot, the batteries were far warmer given they just had their life drained out of them.
After further testing, it is the inventor dropping the output voltage when the input voltage drops to a certain voltage, so nothing to do with the batteries.
So given this, there was potential for the batteries to provide another ~3 minutes at the same current, that would equate to almost 24-25 minutes runtime at that power.
The other thing to note is that the low voltage cutoff didn’t activate at 5 volt (2 x 2.5 volts in series), I’m not sure the tolerance on this and I didn’t want to take them down to far so ended the test just past the 5 Volt mark.
All up I’m impressed with these cells, such high current through a protected cell is novel and provides a nice safety aspect when compared to unprotected cells and would recommend them for high current applications.
The batteries are 21.5mm (0.846”) by 74.8mm (2.944”) in width and length respectively, and weight 73 grams (2.57 ounces) each, although when I weighed them, they were slightly lighter at 70 grams (2.47 ounces).
The batteries are protected cells that means that they are approximately ~5mm (0.196") longer than unprotected cells. For majority of lights and other common low power portable devices this shouldn’t pose a problem, but for high current devices that typically use unprotected cell this extra length could be an issue.
The nominal Voltage is 3.6volt with a discharge cutoff at 2.5 volt.
And a capacity of 5000mAh with a massive max discharge current draw of 25A! (That’s impressive for a protected cell)
Other details from the Xtar website:
- Charging voltage: 4.2±0.03 V
- Charging current: 2.5 A
- Storage voltage: 3.6 – 3.9 V
- Over current protection: 25.5 – 35 A
- Operating temperature: -20 – 50 °C
- Storage temperature: -20 – 50 °C
- Internal resistance: < 23 mΩ
- Cycles: > 500
I don’t have the means to test these batteries using a dummy load to test the full stated current delivery of these batteries, but I thought I do something more real life in the way of testing.
What I have set up is the following:
The batteries are connected in series to produce a voltage of 7.2 volts and are connected to a DC-to-DC boost inverter to step up the input voltage to 24 volts. Connected to the inverter is a very high RPM fan (the likes of what you see in a Dyson product, the thing has a very impressive airflow)
The inverter unfortunately has an input current limit peak of 12 Amps but also has a very low input voltage of 4 volts, so it can’t test the full current but can test down to the cutoff voltage.
Specs of the inverter:
- Input voltage: 4-35V
- Output voltage: 5-35V
- Output power: long-term within 100W, peak 150W.
- Input current: within 10A for a long time, peak 12A; ß I’m pushing this
- Efficiency: 96% (measured by 12 to 19V4A)
Here is a video of the test being performed (4 minutes of riveting viewing
)And the results from that test
Not sure what happened around the 21:30 minute mark, I suspect that the input voltage to the inverter dropped enough that the inverter dropped the output voltage and thus reduced the current draw.
It could have also been a thermal protection as the inverter is only rated for 12 Amps for a short duration (21 minutes is short, isn’t it?
), saying that, the inverter wasn’t overly hot, the batteries were far warmer given they just had their life drained out of them.After further testing, it is the inventor dropping the output voltage when the input voltage drops to a certain voltage, so nothing to do with the batteries.
So given this, there was potential for the batteries to provide another ~3 minutes at the same current, that would equate to almost 24-25 minutes runtime at that power.
The other thing to note is that the low voltage cutoff didn’t activate at 5 volt (2 x 2.5 volts in series), I’m not sure the tolerance on this and I didn’t want to take them down to far so ended the test just past the 5 Volt mark.
All up I’m impressed with these cells, such high current through a protected cell is novel and provides a nice safety aspect when compared to unprotected cells and would recommend them for high current applications.
