This is one of my prototype projects that I completed a while ago, and finally got it back from the patent attorney, which took ages. This is my own project, and not an MGI project.
However, I thought I'd post up a thread about it, because it is a unique idea that solves the battery life issues with the Eotech sight.
And it doesn't add really anything to the weight or bulk of the sight.
It's a very clean package that uses unbreakable, flexible solar panel technology, and makes use of the existing Eotech support frame as the platform.
At this time, I've only tried it on the AA battery model.

Here are a couple of pics:




The solar charger recharges the batteries at a rate approximately twice as fast as the sight can pull down the batteries on the brightest setting. So, as long as you are out getting some sun on the unit, like on patrol, the sight will recharge more than is being used.
The batteries will never go dead with this application, until the batteries simply give up and can't accept charging anymore. Or unless you put the thing in a dark closet for months and let the rechargeable batteries self-discharge, which is what all rechargeable batteries do anyway.
So, a few hours of sunlight daily, or every few days, will keep this sight up and running indefinitely.
The solar charger is powerful enough to bring these batteries up from dead-flat to a working level in just one afternoon in the sun. After that, it will continue to charge the batteries every day in sunlight, even while you are using it, until the batteries become fully charged.
The charge voltage is set so that the batteries will never cook and be ruined, but will attain maximum charge.
I used NiMh batteries, to eliminate the charge "memory" that happens with NiCd batteries, and NiMh has no "memory" so it doesn't matter if you are charging up to full or anywhere in between. It doesn't affect the capacity of the battery to function well.

It's a totally passive system to the user. It just does its work without any need for attention from the user. As long as you're out on patrol, or in the sunlight, it will charge.
The location of the solar panel is up high on the protective arch, and will have good chance of exposure to sun in most any circumstance when the gun is not stored away.
Even a bright indoor light will do the charging too.

The unit is still watertight with this system, and there are no parts that compromise the integrity of the Eotech. Even in a massive destruction of the protedtive arch that would take out the panel, the batteries will still operate the unit, just as they would have before adding the solar panel. No capabilities have been reduced from the normal operation, but charging has been added.

In this configuration, the Eotech sight will virtually never go dead. Even if the batteries did go dead from long-term storage in a closet, this system will get them going again in one afternoon out in the field.

It's like a "fail-safe" system for the Eotech battery power.

The panels are not totally indestructable, but they are not glass, or any other material that could break on impact.  It can be dropped. The panel can even take some damage clear thru it, and still operate. However, it could be scraped heavily to the point that most of it is torn off the protective arch, or damaged beyond repair. Some care will be required to avoid this type of scraping and tearing damage on the top of the arch of the sight.
It is quite durable however, so pretty much unless you try to wreck it, it will do fine.
And in the unlikely event it was damaged too badly, as I previously mentioned it will not interfere at all with the normal function of the sight with the internal batteries.

The solar panel itself is about the thickness of 35mm film, encapsulated in a mylar laminate, and bonded to the top of the arch. So, added weight is no concern. It does not protrude out from the confines of the arch top, so there is no added bulk.
Small insulated wires leading to the battery compartment are protected inside the arch, until they enter the battery compartment behind the water seal. The method I used does not compromise the watertightness of the seal.

So, all in all, this is a clean, durable, and useful application to essentially eliminate any concerns about battery life with the Eotech sight, that is passive to the user, and doesn't present any compromises in weight or bulk.

I thought it was pretty cool. A fun invention project.
After I got it back from the patent attorney yesterday, the batteries were dead flat, because he had it in his closet for months. I just put it out in the sun yesterday afternoon, and by dinner time it was working like a champ.

Happy to answer any questions.


Edited to add:
Due to the amount of interest generated by this thread, I'm now doing this mod to your Eotech AA model that you send in to me to be modded. Contact me by IM or email if you want to get your sight modded for $100 plus shipping.

At this time I'm not set up for any production of this item.
I could make the mods by hand, to people's existing Eotech AA models.
I could probably do it for around $100 for parts and labor in my spare time.

The patent attorney stuff is expensive, but that's the way things go.
I'm not expecting anybody to pay for any of my attorney costs.

Also, while I can do some of this stuff in my spare time, I have to attend to my daily job. I don't have any production line or anything. It would be all hand-made, one at a time. So, if I get a pile of requests, there could be some waiting time involved for me to have a chance to finish all of them.

While it is not well-known by the general public, lead-acid and alkaline "non-rechargeable" batteries can also be recharged a few times. Probably to lower than max capacity, but it can be done, and people do it.
The key is a low charge rate, which this panel supplies.
So, even if it is not an optimal application with non-rechargeables, it can work to some extent with them, and wouldn't be likely to force overcharge leakage from them.
I'd suspect that even if a non-rechargeable set of batteries was in there, it would be fine for a while, until you could get some NiMh batteries into it.

This system is "self-regulating" to the extent that as the battery voltage increases near max, the amount of charging decreases due to the "evening out" of the difference between the charging voltage and the battery voltage.
This isn't one of those "battery burner" quick-chargers.
It's a trickle charger.
The working charge voltage is just over 3v, so when you put a pair of 1.5v alkalines in there, the full voltage of the batteries is almost level with the charging voltage. So nothing dramatic is going to happen.
In fact, the alkalines will take some charging as they run down, for a few times.
During that time, it would be advisable to find some NiMh type batteries to replace them with.

Quoted: Quoted: I always find my EOTECH DEAD And this is what makes the idea of a solar charger so silly. The fact that you are relying on an optic to begin with that places such high demands on a batteries. Aimpoint has it right. Add new battery before your one year deployment then turn it on and forget about it.

Yes, I've worked on something for Aimpoints too, but I felt it was unnecessary with the newer versions.

However, some people prefer Eotechs.
This is designed for their needs, and for people who have them in regular use..
If you like your Eotech, and are concerned about the battery situation, this is a way to help.

Quoted: Awesome I always find my EOTECH DEAD

You have a problem then and need to call the company.  Mine I have never had a set of batteries go bad although I replaced a set two years old just because.

Good job Tom!

Quoted: Without going into too much detail, could this system be made into a stand-alone kit for home installation? You could sell the system as a kit and also offer installation depending on the requirements of the customer. A solar powered optic would certainly swing me toward the Eotech over the competition. ZM

Yes, it could be done as a kit.

Quoted: Man, just when we think you have thought of everything, you think of something else. You are turning into the Edison of modern firearms. And I know you will show this baby to us at SHOT, right?

I certainly hope to be at the SHOT Show this year.
I actually had it at SHOT last year, but only displayed it to a few people.

Quoted: Quoted: Quoted: I always find my EOTECH DEAD And this is what makes the idea of a solar charger so silly. The fact that you are relying on an optic to begin with that places such high demands on a batteries. Aimpoint has it right. Add new battery before your one year deployment then turn it on and forget about it. I guess there's no plans to make a solar charger for night vision and thermal sights?

I hope the mil folks or for that matter the EO folks give you a good size check to buy your patent!

Quoted: I guess there's no plans to make a solar charger for night vision and thermal sights?

I can do this for virtually any application that can use a form of rechargeable battery.
I just need to have the data on the electrical requirements, and a place to laminate the panel on the housing.

In other applications, I have laminated larger panels like these onto Crane/LMT type buttstocks, and provided battery charging for the batteries that are in the battery storage tube.
Other applications are also possible.
Call me to discuss.

Quoted: I hope the mil folks or for that matter the EO folks give you a good size check to buy your patent!

Victor,
If you think that something like this solar charging would be a benefit for items that you sell, please contact me and we can talk about what can be done to suit your needs. I can make something for almost any application that uses rechargeable batteries, and I have enough experience in this to be creative for the special needs of  the application.

Quoted: Whatever happened to the idea of a centralized energy source to power all the devices that need electric power, opics, lasers, NV/thermal devices, etc. that heretofore use their own batteries and have their own battery housing?  I think the solar recharging can be of huge service if the centralized power pack ever comes to light.  Imagine if the EOTech, lasers, NV/thermal devices doing without their bulky battery housing, they can be made much smaller, and we wouldn't have to carry all kinds of batteries with us

This application you see here, and some others, was the preliminary work toward the centralized power source of which you speak.
I needed some experience in powering various devices, and I did that by doing on-board charging as the initial foray.
I've worked on some things to integrate it all together too.I have a variety of other stuff on the drawing board to distribute power, and keep it all waterproof for SEAL and commando use.

The issues involved are the interconnecting circuitry, and the needs for a variety of voltages/currents for the different devices vs the battery storage capacity and charging capacity.
It can be done.
It is cumbersome in the AR15, because of the layout.
Also, I'm not wealthy and have to do this stuff out of my back pocket, and that pocket is not deep. I'm basically just a working stiff that sells some stuff on ARFcom for commissions.

As it turns out, the individual charging systems that are integral with the device provide an inexpensive and viable solution that isn't too complex, and isn't weapon dependent.
I can take this concept as far as anyone needs.
I've been doing solar power in many applications from homes and businesses, down to specialized applications like this, for years now.

Quoted: Are there any solor panels that don't have the white "box" outlines on them? Some people may not like the grid pattern this puts on the guard. What about the "memory effect" seen in other recharging cells.  I understand this will be  unlikely, but I think people may want to hear it from you.

I have never seen any panels without the grid pattern.
These are the cell junctions, and are pretty much inherent in solar panels with the existing technology.

The "memory effect" isn't present in the NiMh battery chemistry, which is why I selected that chemistry for this use.
The NiCd batteries do have "memory effect" which can reduce the effective capacity of the batteries if full charge/discharge cycles are not used.
NiCd batteries can be used in this system, but I felt that the elimination of the memory effect by using the NiMh batteries was more important than the slight improvement in self-discharge rate available from NiCd.
This is a "shallow cycling" design which would have adverse affects from "memory effects" present in NiCd batteries.

Quoted: That really neat! How about making solar rail panels?  You using one rail panel per device that needs to be charged.

Can do.

i am in when it's ready im or email me. this is somethingi'have been wondering about being possible for awile.