T-slim charging

Haha. I do not. Did you get the optional tampon dispenser?

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I bought used and that feature wasn’t available yet. So I built my own. For my wife.

But I have one in my truck. It’s called a toolbox. Cause I’m secure in my manhood. :slight_smile:

Ladies if you take offense to this please direct your flames to Sam.


My father raised me right and taught me many useful skills. When I left home at age 18, he gifted me a well-stocked toolbox. I miss him. :heart:

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Sally7, please PM me with your address/GPS coordinates. In the event of a ZA (and I repeat: it’s just a matter of time), we will get to your home as quickly as possible. If you are still alive, you may join us. If not, your stash will be greatly appreciated.

The first solar charger I bought was a cheaper (& flimsy) version I picked up at the auto parts store. It was my mom-solution for my daughter’s excuse of no phone battery/no place to charge. It didnt survive a fall from the top of the stands at a football game, but this one is much tougher, or maybe she’s more careful.:grinning:

I have had my Tslim for 3 months. I love, love, love it. As for charging it, if you are comparing it to the batteries in your other portable devices don’t. It’s worlds ahead. The rechargeable battery amazes me. I charge it every 2 or 3 days and it takes me about 10 minutes. Camping? I use a portable charger. However, that is only because I don’t like it to get below 70%. I haven’t tested it out, but I believe I could likely go weeks.

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.

Thank you,
AKA: YouTube Diabetic Opinion, and Gadget Review Videos

Gadget Review Videos URL

Diabetic Opinion URL


One word:


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LOL, thanks. I think :sunglasses:
I may not post often but when I do I try my best to make sure the information is accurate so people are not miss lead or given the wrong information. It takes more time, but I think it’s worth it if it helps others. And I just happen to have a lot of experience with electronics and different batteries. So the topic mixed happened to mix in two areas I was familiar with.
When the pump was in its first year some were concerned about the charging temperature and I did a video on this. I think now that I have more years of learning electronics and better equiptment for testing I might have to redo this video and include some of this topic also.
Wow, I just watched this video again for the first time in over three years. I should redo this now that my electronic review channel is much more profesional and better video and audio. The new one needs to get rid of the hand help camera motion. Those were the good old days with using a cell phone camera and no tripod :unamused:. When I do a new a better one I will remove this one and update this comment if I remember.


Please do!!! This sounds like something our members should know about!


My comment was meant to be a compliment, so you’re very welcome! :grinning:

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Wow. Thanks so much @ScottD for sharing this valuable and as @rgcainmd mentioned, thorough information. Really appreciated! :blush:

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Your welcome.


Scott, this is one heck of a good post. Thank you!

You welcome, glad you liked it.

400 watts is a lot to pull from your vehicle cigarette lighter. If you do connect enough devices, you could blow a fuse depending on your vehicle. I do like the vehicle power inverters for their convenience for some devices but really not necessary in this case. In any event, just be careful how much power you pull through it.

When considering switching to the Tandem t:slim X2, I was initially of the opinion of @rgcainmd and thinking replaceable batteries would be better for a pump. That is what we were used to - the standard AA lithium battery. Easy to get anyway and always a good supply kept on hand.

However we found our reality (after switching onto the Tandem t:slim X2) was more of what @ccc mentions when they say it was found to actually be less of a hassle.

Here is a nice article from the Tandem Diabetes website in regards to charging preferences from a (likely non-scientific) survey done on their user base:

For portable charging, we use @Sam19 suggested approach of the portable batteries. We carry portable batteries. We also use a dual USB charger in our vehicle that plugs into the cigarette lighter. These are all standard outputs and are not a problem at all with the t:slim as well as being able to keep the Dexcom receiver charged, the iPhone, the Android, all the gear.

My choices for charging all these devices (on-the-go, vehicle, home):

The Anker products I have bought, tested and abused and fully trust them.
The mini USB portable charger is probably using a Panasonic 18650GA battery, good stable strong betteries that will last.

I tend to spend a little more money on my cigarette lighter charger then $10. You do get what you lay for, and when they fail from to much heat you can only hope they fail open in a way that cuts all the power or else you ignore have 12 volts instead of 5 volts for the USB going to the device you are charging.
Concidering the cost of the pump, the phone or tablet you might be also charging from this USB port. The more power they can provide the hotter they run. Not remember they sit in the car on a hot summer day so it’s already hot meaning more likely to fail if you try to charge something draining s lot of power like a tablet.
I suggest staying away from the cheap USB wall chargers and the cheap car USB chargers. I have taken enough of them apart to know what one scare me and it’s usually the cheap ones at the front of the stores at gas stations, pharmacies, convenience stores that scare me the most.

I’ve also taken apart the good ones like Belkin, Apple, Samsung and have seen the difference. I recently took apart one of the apple little square ones, I even sawed through a surface capacitor and I couldn’t get it to fail after I did that. It still works even under the heaviest load it’s designed to run.
My girlfriend also was using one of these to charge her Samsung phone and said the charger isn’t working. After looking into it I found out the charger was turning off because it detected a short in the micro USB cable, the charger was fine, the cable was bad, but the fact it turned off to save the phone from further damage was great.
Same with a 6 port anker 60 watt USB hub from Amazon. I thought a USB port dies, but it was smart enough to see a bad cable and turn off just that one USB port and keep the others running. After replacing the cable and unplugging the USB charging hub, then plugged it back in the port came ba back and still run OK today.

As for inverters, don’t buy cheap. I’ve seen them blow up in front of me without the proper protection it should have had. A 400 watt inverter would probably over draw the cigarette lighter. My little 60W inverter for a cigarette power lighter adapter draws 8 amps. I would check the manual for you car, or sometimes it’s written on the outlet for the max power that can be connected to the lighter plug.

Wow, so I looked at that unit and on top it says the input power is D.C. 12V, 39.2 Amps. That’s 470 watts of power this inverter can pull when used under full constant load.
Most car lighters for power are marked, or it’s in the manual. The average on most of them say max power 12V/120W.
So take 120 watts and divide it by 12 volts and you get 10 amps.
Most inverters on a stage are only about 90% efficient, meaning it will always draw more then it give you in total power of watts. When you invert DC electricity to AC electricity their is always a loss of power. That’s why your unit drains 470 watts but is only rated to give you 400 watts.

If you pulled the full power of your inverter over a cigarette power lighter plug at 39.2 Amps I would hope a fuse in the car would blow. If it doesn’t blow or if the line isn’t fused it will melt the wires and cause a short in your cars electrical system and even probably a fire.

The most inverted power I would pull from a car outlet would be a 75 watt inverter because of the loss of power the inverter would also need to use to convert the power. These are designed to be hooked up directly to a battery, I don’t know why they give a lighter plug for a unit that big.
Also unless you buy an inverted that’s $500 the cheaper ones do what’s called a modified sine wave. A lot of recharagble devices like laptops don’t like this modified AC power from an inverter and can damage the laptop or other recharagable devices. Read the manual, it should say all this. I know my MACBook laptop doesn’t like the power from my battery backup when the power goes off in the house. A uninterrupted power supply from a company like APC for inside homes have the same modified AC power signal.
Be careful, or you could end up damaging your laptop.

Now that’s I said all this, I will also say if your only pulling 70 or 80 watts total from what your plugging in when using the cigarette lighter plug then this might be OK. The inverter will only pull up to thenstated 39.2 Amps if it needs it, so if you keep what you have plugged in low then it might be alright. But you need to know how much wattage each device you plug in uses.

A permanent solution will be a good inverter.

I saw another product on Amazon that looked particularly nice. And cheap.

$19 on Amazon.

The concept is put 4 AA batteries in it and it has a USB output to be able to provide charging capabilities for any device which charges via USB port. For example a Tandem t:slim X2 pump.

Couple this with a package of AA batteries which can be purchased with a 10-year shelf life for about 50 cents per AA battery and this is a decent power backup solution for smaller devices which can sit on the shelf a long time while still be ready in an unexpected situation.