mAh or Wh: which one really tells you something about a power bank?
A battery’s capacity is almost always given in milliampere-hours (mAh). But a mAh at 3.7 volts is not the same as a mAh at 7.7 volts. What you want to know is how much energy the capacity of the power bank, which is measured in watt-hours (Wh):
Wh = mAh × volts ÷ 1000
- HeatCore10k: 10,000 mAh × 3.7 V = 37 Wh
- PowerCore20K: 5,000 mAh × 7.7 V = 38.6 Wh
The HeatCore10k reaches its capacity at the voltage of a single battery cell (3.7 V). The PowerCore20K specifies its capacity at the voltage of the battery pack (7.7 V). If you convert both to Wh, you’ll see that they contain almost the same amount of energy, and that the PowerCore20K actually has slightly more.
What does that mean for your heating and battery life?
There are two things that matter to you: how long you stay warm and how warm your clothes get. The mAh rating on the box is a secondary consideration.
- Battery life: When used with the same 7.4V clothing and set to the same heat setting, both power banks last for roughly the same amount of time. The PowerCore20K has over 4% more energy on board, so it lasts just a little longer.
- Heat: The PowerCore20K also supplies 12 volts via USB-C. This means that the 12V versions of our heated jackets and body warmers, which operate at a higher voltage. Those garments do not work with the HeatCore10k.
In short: with the PowerCore20K, you don’t compromise on battery life and you have more options.
Charging: approx. 5.5 hours compared with 2 to 2.5 hours
You’ll notice the biggest difference when charging. The HeatCore10k charges via USB-C at 5V 2.1A and takes about 5.5 hours The PowerCore20K supports fast charging via USB-C Power Delivery (PD) and, when used with the VST Charge 20W fast charger, takes approximately 2 to 2.5 hours full again.
Handy if you realise in the morning that your power bank is flat, or if you want to head out again in the evening after an afternoon on the slopes or in the stands.
Connections and LED display
Both power banks have a 7.4V DC socket for your clothing and a USB port for charging your phone, for example. The PowerCore20K can do more:
- USB-C PD (input and output), up to 12V: fast charging and connecting 12V clothing.
- USB-A (output), up to 12V: for your phone or other device.
- DC (off), 7.4V: for all our 7.4V clothing.
- LED display: You can see at a glance how much charge is left. No surprises halfway through your walk.
Everything at a glance
| HeatCore10k | PowerCore20K | |
|---|---|---|
| Capacity | 10,000 mAh at 3.7 V | 5,000 mAh at 7.7 V |
| Stored energy | 37 Wh | 38.6 Wh |
| Suitable for | 7.4V clothing | 7.4V and 12V clothing |
| Charging | USB-C 5V 2.1A | USB-C PD up to 12V |
| Charging time | approx. 5.5 hours | approx. 2 to 2.5 hours |
| Exits | DC 7.4V, USB 5V | 7.4V DC, USB-C and USB-A up to 12V |
| Display | No | Yes, LED display |
Choose the HeatCore10k if…
- you only have 7.4V clothing;
- if you’re looking for an affordable spare power bank;
- you charge it at night and the charging time doesn’t matter.
Choose the PowerCore20K if…
- you have, or would like to be able to use, 12V clothing;
- you want to feel full again quickly (approx. 2 to 2.5 hours);
- you want to see how much charge is left;
- if you want the most power from a power bank.
Take a look at the PowerCore20K or the value pack containing 2 power banks and 2 fast chargers
Frequently asked questions
Does the HeatCore10k last longer because it has a higher mAh rating?
No. The HeatCore10k specifies its mAh at 3.7 V, whilst the PowerCore20K does so at 7.7 V. Converted to energy, that’s 37 Wh compared to 38.6 Wh. So, with the same clothing and heat setting, they last about the same length of time, with a slight advantage for the PowerCore20K.
Will the PowerCore20K work with my 7.4V jacket or body warmer?
Yes. The PowerCore20K supplies 7.4V via the DC socket, just like the HeatCore10k. You connect it in the usual way.
Does the HeatCore10k work with 12V clothing?
No. The HeatCore10k only supplies 7.4V to your clothing. For the 12V versions of our jackets and body warmers, you’ll need the PowerCore20K.
What’s the quickest way to charge the PowerCore20K?
With a USB-C fast charger with Power Delivery, such as the VST Charge 20W. It will then be fully charged in about 2 to 2.5 hours. With a standard 5V charger, it takes longer.
Can I charge my phone with these power banks?
Yes. Both have a USB port. The PowerCore20K also has a USB-C port with Power Delivery for faster charging.
Conclusion: the PowerCore20K is the better power bank
Don’t be misled by the mAh figure. In terms of energy capacity, the HeatCore10k and the PowerCore20K are virtually identical, with a slight advantage for the PowerCore20K. What’s more, the PowerCore20K charges to full capacity in just over half the time, works with both 7.4V and 12V clothing, and the display shows you exactly how much charge you have left.
Do you only have 7.4V clothing and are you looking for an affordable replacement? In that case, the HeatCore10k remains an excellent choice. For all other situations, we recommend the PowerCore20K . Take a look at all our batteries and power banks.
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