The pump logs charge times and percentages. It logs when the battery drops every 20%, when you start to charge it and when you stop charging it. This should give you a good idea of the average battery life. I spent a lot of time on this and hope it helps. Don't get concerned or think the pump is complicated from these logs I'm sharing, it's not, it's easy to use and learn. Most T:Slim pump users don't even look at these logs, but the techie and engineer in me like to look at these sometimes. Some good information can be found like how often I charge the pump and how long it takes to charge.
More details and suggestions answering question about charging can be found under the logs I posted explaining what these logs mean.
It may be a little long, but we are talking about a very expensive pump that your life depends on.
For a baseline I use 0.72 units an hour.
I use a total of about 245 units to 260 units every 5 days. I mention this because changing the cartridge and priming may use a little more battery life.
NOTE: Unlike most people I only change my cartridge and refill my pump every 5 days. This is NOT recommended, the recommended way is change the cartridge and refill every 3 days. But I also know Novolog is good for 6 days once it's extracted from the vial according to the novolog data sheet. I am in no way suggesting you do this yourself.
The more you use the pumping then the less battery life you may see. And the less usage then the more battery life. Just like using a cell phone, the battery may drain faster the more you use it.
Since I never really checked the logs before to figure out battery life and usually just charge it when it alarms at 20%, I figured I would look at them and share them with everyone. You will notice I don't always charge it up to a full 100%, I sometimes just put a little more charge on it.
11/26 - Last full charge to 100%, this charge started with 35% at 1:46am to 100% at 2:53pm. So it charged 65% in just over 1 hour.
12/1 - battery logged drop to 60% at 3:46pm
*12/3 - Changed the cartridge, this may take a little more battery with priming.
12/4 - Battery charge start with 40% at 6:33pm to 85% at 7:09pm
12/5 - battery logged drop to 80% at 11:37am
12/7 - battery logged drop to 60% at 11:59pm
*12/8 - Changed the cartridge, this may take a little more battery with priming.
12/10 - battery logged drop to 40% at 6:25pm
*12/13 - I decided to charge it a little when it alarmed at 20%. Also confirmed in Alerts and Alarm logs.
12/13 - battery charge started with 20% at 12:17am, and ended with 45% at 12:45am
12/14 - battery logged drop to 40% at 11:48pm
*12/14 - Changed the cartridge, this may take a little more battery with priming.
12/15 - battery logged drop to 40% at 5:23am
12/17 - battery charge started with 25% at 3:03am, and ended with 100% at 4:17am
*12/19 - Changed the cartridge, this may take a little more battery with priming.
12/20 - battery logged drop to 80% at 8:00pm
12/21 - battery charge started with 75% at 7:41pm, and ended with 100% at 8:18pm
12/25 - battery logged drop to 80% at 6:18pm
12/28 - battery logged drop to 60% at 1:33am
12/29 - it was at 55% before I started checking logs, it dropped to 45% because I just spent and hours looking through all the logs.
NOTE: All my personal chargers or USB ports when charging in the above logs are rated for 1000mA of current or higher. This may or may not affect the speed of the charging if you have a charger that is 500mA or a computer USB 2.0 port rated for 500mA. I never checked, but now I plan to do some testing to see if a higher current charger affects the charging time and speed. I'll post my results once the testing is completed.
Like most mobile devices the screen takes up most of the batter, so checking the logs kept the screen active for an hour. I have my screen to turn of off after 30 seconds. On average for me the battery seems to drops 20% every two day, or about 10% daily for my usage.
I had one week it discharged faster from starting a new medication that caused my sugar to spike above 450 for a few days, so I was bolusing every 2 hours, and one night with no sleep that night. Needless to say this took more from the battery power.
As for battery USB portable chargers I find most of them are good for charging the pump. I wouldn't buy the $3 special at the dollar store or eBay. Spend a little more that way it has protection and is reliable. If you can find a battery bank that is UL listed this would be the best and I think it was also a requirement Tandem had to follow for the charger they provide with the pump. UL listed just means it was thoroughly tested and is less likely to cause a voltage spike that could damage the pump and has protect and controls to maintain the required 5 Volts for the USB port charge.
DO NOT USE THE CHEAP ONES FROM THE GAS STATION OR OTHER PLACES LIKE THIS. You would be risking a $6,500 pump to save a few dollars on a charger and it's not worth it. This goes for all chargers, car chargers, battery bank chargers and wall chargers. I wouldn't even risk these cheap chargers with my cell phone, and definitely not with my pump.
I recommend one that can charge at least at 1000mA (or 1 amp), but a 500mA battery pack will also work it just might charge a little slower. The charger provided with my pump are both rated for 1000mA output current and UL tested and listed.
If you decide to use one rated for a tablet like an iPad at 12W (or 2.4 Amps) this would still be ok. You can not force current into a device charging, mobile devices including the pump will only draw what it need based off the battery charging circuit algorithm. The algorithm changes depending in the kind of battery used in the mobile device. I won't get into details on this, it can get complex and long winded.
The main point is higher current won't hurt the pump. Higher current over 1000mA may not charge the pump any faster like charging a tablet would. So you don't need the more expensive 2.4A USB portable battery pack unless you want to use it for your tablet also. The main thing is that the charger maintains the required 5 Volts on the USB port. Cheaper battery banks sometimes drop down under 5 Volts when charging something and could damage the pump if the voltage drops to low, or of the voltage spikes to high. So don't buy the $3 special battery banks, it's not worth the risk.
Also even the best chargers performance can be impacted from the quality of the USB cable. Again don't buy the $1 special cables. If you looking for quality cables at a good price you can search Amazon for "Anker Micro USB cables". I have tested these cables and many other including the Amazon branded cables and these are good cables and a good price. Cheap cables will also slow down the charge current and you may notice other micro USB devices charging faster with better cables.
If others are wondering how to see these detailed logs, they can be found in OPTIONS > HISTORY > COMPLETE then you can look at everything for each day.
Ok, well I said enough and spent a lot of time on this, I hope this doesn't go to waist and helps some people. If I have time I will do my charging testing video and post it on my YouTube channel. I'll return and share that URL when it's done.
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