Larger battery, no other gimmicks please

Which mode is your light using during those 4 hours? How old is your varia?(wondering that maybe battery life decreased during a long usage time)

I own my 515 since beginning of this year. 

I've never had until now issues with the battery on rides over 5 hours(6, 7, also 10+h). It's true that, if planning longer rides, I make sure before the ride the varia battery is around 100%.

As for the mode used - I'm using SmartBikeLights data field to control the lights. For example it's "day flash" when a vehicle approaching around 350-400m away. It's solid when applying hard breaking. In rest it's OFF all the time. Manually set to "peloton" when I have another rider behind me. 

With this, up to now never reached into low battery on longer rides. Before having the data field installed to control my light, I've used it in "day flash" all the ride but I do not remember if I had rides longer than 5h. 

L>E> Of course, it would be nice and I would really appreciate if there will be a version with larger battery but with the same specifications (e.g. no camera). 

I have a similar problem with the battery. I'm using smart light (automatic). Varia was replaced once, but the battery life is the same. It's about 8 hours. It's far away to suggested 16 hours. 

The Varia radar is a great invention, unfortunately after four years of heavy use, my battery died after just an hour. Garmin's policy does not provide for repair, only a discount on new equipment. And I don't like to produce e-waste, so I changed the original battery to a 18650 cell. There was a "hump" from the 3D printer, but the capacity of 3000mAh (compared to the original 1400mAh) compensates for it.

Great idea! I'm thinking about something similar, do you have more photos of your replacement?  

Below are some photos. Unfortunately, I'm not a machinist :/
The most difficult thing is to disassemble the radar, it is glued together. Only force here. Then you can seal it with silicone.
It is also worth noting that the original battery is of the LiIon HV type, charged to 4.3V. That's why you must use one! (e.g. Samsung ICR18650-30A). I also used the protection circuit from the original battery, commercially available are usually 4.2V, and the radar shows an error on charging.

Thanks for the photos :)

If you have a 3D printer, it is also possible to print the entire "back" of the radar and leave only the original front red part? Just wondering... So maybe even 2 batteries can be placed here? And it will double its capacity.

Designing and printing the entire "back" is beyond my capabilities. There's a USB connector that needs sealing, and a very precise switch that's also sealed.

The Op probably lives in an area of high traffic and the radar is always detecting cars using more battery.  Another suggestion was to give the user an option to turn the radar off, light on.  I think Garmin can do it and make the warning in the upper right red if the unit is off to protect themselves legally. 

KS0524 Would it be possible to provide the 3D files?
If so, thank you very, very much!