# New DIY Battery Holder



## OverTheHill (Dec 3, 2004)

DigiKey have some single 18650 battery holders which is at the top of the picture.

Part # BK-18650-PC2-ND

They are made to mount onto a PCB and have a couple of small tabs running from the contacts through the base. One nice thing is that the contacts slide out so I snipped off the tabs before soldering on the leads.

I hot glued two of the holders back-to-back and then drilled some holes and soldered on some leads (quite fiddly). I now have a very nice and compact 7.4V battery holder which holds the batteries very snuggly. The nice thing about these is that you can configure them how you want

Regards,

OTH


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## jbflyfshr (Jul 24, 2006)

SWEET!

Options are always good to have...

Thanks for sharing.

JB


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## El34 (Jan 11, 2009)

Yes, thank you for the info.

I'm gonna get some and see if I can use these instead of machining my own, which is time consuming and way more expensive.

Digikey does not have much info on these like most other parts.
No technical drawings etc.

What is the plastic like?
Soft, hard, thin, etc???


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## HEY HEY ITS HENDO (Feb 23, 2008)

very nice! .... £1-75 each
http://www.digikey.co.uk/
it looks like LDPE same as the AA type battery holders


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## OverTheHill (Dec 3, 2004)

El34 said:


> Yes, thank you for the info.
> 
> I'm gonna get some and see if I can use these instead of machining my own, which is time consuming and way more expensive.
> 
> ...


The company they are made by are Memory Protection Devices Inc.

http://www.memoryprotectiondevices.com/

Actually tracking it down on their website is a challenge but here is the tech. drawing:

http://www.batteryholders.com/BK-18650-PC2.PDF

As Hendo says they're made of polyethylene like other battery holders.

Regards,

OTH


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## Vancbiker (May 25, 2005)

One fairly big thing I do not like about this design is there is no protection against incorrectly inserting a cell. That being said, I've ordered a dozen. Though I like the round 5 cell holders I have built, this is so cheap that I'll live with the possible reverse polarity issue.


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## El34 (Jan 11, 2009)

yeah, you know someone is going to install a battery backwards at some point.
I have installed batteries backwards in every device I have ever owned.

I don't really like battery packs, but people ask for them and so I make them.

I solder all my personal packs so there is only one way I can hook the pack to my lights and my charger. 

It's fairly easy to be in a hurry and install a battery backwards.

I ordered 10 of these to check them out.
My CNC'd 18650 battery holders are a major PITA to make and assemble.


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## OldMTBfreak (Apr 8, 2006)

EL I feel the same way. If I can possibly do it backwards, I will. I always solder my battery packs. Since I charge my batteries with a large lab power supply, this thing would blow those reversed cells up. In addition to ruining them. I need to keep those $15.95 cells happy! James


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## HEY HEY ITS HENDO (Feb 23, 2008)

"I need to keep those $15.95 cells happy!"
.....  no way man ....... what brand are they??


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## OldMTBfreak (Apr 8, 2006)

I always feel that: "if you want to play, you got to pay". http://www.batteryspace.com/li-ion1...lecell37v2600mah962wh--oemfromjapankorea.aspx


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## El34 (Jan 11, 2009)

Yikes,
$15+ each cell???

Please, no offense to you, but I am finding the cheap Chinese 18650's at $3+ per cell working out quite nicely.

I am always one to pay more for something I feel is really worth it, but in this case, I am getting huge results from Chinese 18650's for very little money.

Just throwing out info, no offense intended.


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## OldMTBfreak (Apr 8, 2006)

No offense taken. Since I want maximum run time with minimum weight, I just pay. Remember, you can't take it with you. Did you ever see a Brinks truck in a funeral procession? I feel that it was sorta like getting married; steady "female companionship" but at a price. lol


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## [email protected] (Mar 28, 2007)

Too bad I didn't read this post yesterday, before I ordered a bunch of driver parts from digikey :madman:

What about removing the stock contacts, doing a bit of creating nibbling to notch the end of each holder and installing these: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=209K-ND? If you're lucky they'll fit the slots already in the holder.

That would let you solder the connectors on the ends of the holder, instead of having to mess around with drilling holes and soldering in odd places.

I've been doing a similiar technique with 18650 battery cases from DX (will edit this to include a photo later). The cases are cheap enough and look OK, but have a tendency to pop open on a hard bounce, and the crack into little pieces if you drop them on something hard. Shoving them inside a length of 29 inch inner-tube helps, and keeps water out if you wrap the ends of the tube over the case.

The other alternative would be to glue the cases to some perfboard and wire stuff up directly to the contacts sticking out of the bottom of the holder. The drawings of the holder make it look like it has mounting holes. Are those any use? I would think and screw or bolt mounted there would interfere with getting the battery inserted correctly.

Mark


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## OverTheHill (Dec 3, 2004)

[email protected] said:


> Too bad I didn't read this post yesterday, before I ordered a bunch of driver parts from digikey :madman:
> 
> What about removing the stock contacts, doing a bit of creating nibbling to notch the end of each holder and installing these: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=209K-ND? If you're lucky they'll fit the slots already in the holder.
> 
> ...


It depends what you are trying to achieve Mark. Yes, drilling holes and soldering the standard contacts is a bit fiddly but you end up with a very neat battery pack with no external wiring or exposed contacts to short.

The holder does have two mounting holes and providing you used a countersunk head they shouldn't interfere with the battery when inserted.

Regards,

OTH


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## El34 (Jan 11, 2009)

I may cut some copper boards on my cnc if it looks like that would be a good way to form a cluster of these and have the wire exit out the center with some heat shrink for strain relief.

I like the center wire deal like on my CNC'd holders here.










Have to get a good look at them first.

I stock those battery clips that Mark linked to so I can tell you how and if they fit onto these holders when I get my grubby mits on them.


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## [email protected] (Mar 28, 2007)

I promised some pix of my cheesy battery holder in a previous post, so I figured I'd add them here.

Here's a shot of the DX battery case with clips installed:









The contact on the left is one of these: https://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=210K-ND

The ones on the right are the ones I mentioned before: https://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=209K-ND

The case is from DX: https://www.dealextreme.com/details.dx/sku.18074
There are some pieces of curved plastic designed to hold CR123A batteries you'll need to cut out of the way (a sharp pair of diagonal cutters works well for this).

To cut the notches in the top of the case, you can use a nibbler tool, or just an exacto knife.

Here's what it looks like closed:









A standard 26 inch mtb innertube cut into a 2 or 3 inch section makes a nice rubberband to keep the case closed. You can insert the whole mess inside a 6 to 8 inch long piece of 29 inch mtb innertube, and then fold the innertube over the ends. If you use velcro cinch straps to mount the final package to your frame or stem, you wind up with a fairly waterproof package. Plus as I've discovered riding on a few cold evenings recently, the innertube helps insulate the battery from the wind and cold a bit.

I look forward to seeing what El34 and others come up with as a way to use this battery holder.

And kudos to OTH for finding this. His 2 cell holder looks way better than mine (damnit!  ). And probably holds the batteries secure enough they don't rattle and create an open connection on rocky downhills (not that mine have exhibited this behavior yet).

Mark


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## Vancbiker (May 25, 2005)

El34 said:


> I may cut some copper boards on my cnc if it looks like that would be a good way to form a cluster of these and have the wire exit out the center with some heat shrink for strain relief.


My initial plan is to mount these holders back to back on a piece of 4mm polycarbonate. I'll mill grooves or slots in the polycarb for the wiring. That will allow the use of the original PCB pins on the holders and allow the wiring to exit the center of the holder assembly and be properly strain-reliefed.

Another thought I have is to make a "block" that would straddle the positive terminal keeping it just slightly below flush with the "block". This would then prevent a connection with an incorrectly installed battery.


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## El34 (Jan 11, 2009)

> My initial plan is to mount these holders back to back on a piece of 4mm polycarbonate. I'll mill grooves or slots in the polycarb for the wiring


I'm thinking along the same lines.
Have to see them in person and have a stare down session with them. 

Found this photo on the memory protection web site.
Hard to find these little buggers, they buried it in with the Sub-A holders


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## sdnative (Aug 10, 2008)

*Still like mine...*

Options are good, but I still like my design better 

At about @2.50 each, reduced cost (vs. Luminous) isn't too much of a benefit either, especially when you get into the larger multi packs. Then you have to bother gluing each part together. That type of plastic those single cell holders use melts easy too when soldering, a problem I noticed when I was using AA nimh packs.

I needed a single holder myself though, so good to finally get a source. Thxs


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## OverTheHill (Dec 3, 2004)

Vancbiker said:


> My initial plan is to mount these holders back to back on a piece of 4mm polycarbonate. I'll mill grooves or slots in the polycarb for the wiring. That will allow the use of the original PCB pins on the holders and allow the wiring to exit the center of the holder assembly and be properly strain-reliefed.
> 
> Another thought I have is to make a "block" that would straddle the positive terminal keeping it just slightly below flush with the "block". This would then prevent a connection with an incorrectly installed battery.


I'd like to see your mods when done Vancbiker (and El34 of course :thumbsup: )

Regards,

OTH


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## El34 (Jan 11, 2009)

The labor savings is the big ++++ for me
Anything that cuts my labor way down is worth a bunch to me.

It takes +15 minutes to cut out one of my 4 x 18650 holders on the CNC
Then the assembly labor is roughly 15 minutes.
Even if the parts end up costing more, the labor is a huge savings.

But this is all jumping the gun, I may not like them once I see them.


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## El34 (Jan 11, 2009)

Got the 18650 battery holders in today.

I removed the stock PC board terminals and took a shot of one of the clip on solder terminals I stock. The stock terminals just pull straight up. The plastic has a groove that the terminals slide into and that keeps them from moving. Nice feature.

You would have to remove about 5mm from the top of the holder to be able to have the clip on terminals be low enough so that they contact the center of the battery.

Not really something I want to do, but in case someone wants to know, here ya go.

I'll be using messing around with using the stock terminals and some sort of PC board.

I may just start off with a 4 battery in line experiment since that would be much easier than a 4 battery back to back pack.

Here's some small pics


















Here's links to larger pics
https://www.el34world.com/Misc/bike/images/IMG_2098.jpg
https://www.el34world.com/Misc/bike/images/IMG_2099.jpg


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## Vancbiker (May 25, 2005)

OverTheHill said:


> I'd like to see your mods when done Vancbiker


My first use of these holders is in this thread...

http://forums.mtbr.com/showthread.php?p=6372852

So far I am pleased with these. I am still thinking of some way to polarity protect them. Though I have never put batteries in backwards in anything:lol: , I sometimes loan my stuff to others.


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## mtb_robs-x (Dec 13, 2009)

definitly need more options for 18650 battery holders !

good to know digikey has some.

any good single / double cell chargers ? 

and ones you get into , parrallel cells, it gets tricky, but for low current, and low wattage,
the flexibility is still king. for the nimh , don't think, anybody is using battery holders,
and then have a load of chargers,.... but with li-ion, I do see a small comeback, so there is some potential. 
For me, I'am working on battery bottle, and fitting the square holders in a circle/ bottle,
is not quiet working out, and then the charger, etc,...
so for a 2cell backup, or helmet light, this will work nicely. but for the big lights,
the charging aspect is the killer.


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## Cat-man-do (May 16, 2004)

El34 said:


> Got the 18650 battery holders in today.
> 
> I removed the stock PC board terminals and took a shot of one of the clip on solder terminals I stock. The stock terminals just pull straight up. The plastic has a groove that the terminals slide into and that keeps them from moving. Nice feature.
> 
> ...


So EL, you think you might start using the DK version battery holders and selling them on your website? Just curious..Anyway, at least these are cheap and look pretty light-weight.

*SDnative* wrote:


> Options are good, but I still like my design better


I'll soon have one of your holders in my grimy little mitts. Can't wait to see how well they work.


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## El34 (Jan 11, 2009)

Hey Cat,
I have some of them here but I have not had time to figure out a design using them.
I can sell the raw battery holder if you need some?


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## Vancbiker (May 25, 2005)

*Second build*

Here is a picture of my second build with these holders before the final assembly to show how I used them. There will be a total of 8 cells in a 4S2P configuration. This arrangement is really simple to wire in this layout. The clear plastic piece has holes tapped in it to screw the holders to and there are slots to allow wiring to accomodate other battery configurations (4P2S or 8P)

I'll put up another picture when it is complete and wired. I am waiting on some short 4-40 screws to assemble it.


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## OverTheHill (Dec 3, 2004)

Vancbiker said:


> Here is a picture of my second build with these holders before the final assembly to show how I used them. There will be a total of 8 cells in a 4S2P configuration. This arrangement is really simple to wire in this layout. The clear plastic piece has holes tapped in it to screw the holders to and there are slots to allow wiring to accomodate other battery cofigurations (4P2S or 8P)
> 
> I'll put up another picture when it is complete and wired. I am waiting on some short 4-40 screws to assemble it.


Neat. Have you tackled the "insert cell the wrong way round" problem yet Vancbiker?


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## Vancbiker (May 25, 2005)

I have not come up with a polarity protection modification yet. Might do that tomorrow since I am waiting a couple days for the hardware to show. I think it will be pretty easy to add a plastic block around the positive terminal that prevents the flat negative end of a cell from making contact


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## zemike (Sep 3, 2007)

Oh, I have asked https://www.memoryprotectiondevices.com/ 2 years ago if they could make a 4x18650 holder. Their answer was:


and minimum order was 5000 pcs.


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## El34 (Jan 11, 2009)

Nice Job Vanc,
You are making some good progress.

I had a litle time last week to fool around with them also.
I was able to solder together a 4 cell holder together, but it is 2 cells + 2 cells, back to back.
Not very easy to do, and I am not really hapy with the results.
I was thinking that this back to back config would fit into water bottles better.

It would be so much easier to lay them out flat as you have on some sort of backer material_. _I thought about using some copper clad circuit board material, but have not had the time to do any further experiments. Black HDPE plastic may work better and look beter than copper clad board.
Back to the drawing board.

keep up he experiments


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## Vancbiker (May 25, 2005)

*All done*

I am liking these holders. This goes together easily. The center plastic piece is 6mm Lexan. It is wired 4S2P and can be loaded with 4 cells or 8 cells depending on how much run time you need. This is planned to strap under the top tube, so I thought the long layout would be better than a more "cube" layout. The downside is there are fewer choices in bags to hold this shape. I dug up a bag from an old Motorola cell phone I had from the early 90's. It will work after I add a bit of foam to it (phone was about 50%larger than this battery!).


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## OldMTBfreak (Apr 8, 2006)

Hi VCB, will the phone bag keep the water out. I guess you could put the battery assy into a plastic bag.


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## Vancbiker (May 25, 2005)

I would rate the phone bag as only slightly water resistant. If I was going for a night ride in the rain, I would put the battery in a plastic bag and tape it around the opening. I rarely ride if it is rainy though. 

I don't have any experience with the 18650 cells getting wet. Do they tend to be sensitive to that? Since the cells have to come out of the holders for charging, everything gets a chance to dry out the. Maybe that works in my favor.


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## OldMTBfreak (Apr 8, 2006)

Well, the water seeps into the protection circuit (in the end of a protected cell) and f's it up. I think a plastic bag should get the job done. Just be sure to give the batteries a chance to dry throughly. I solder my batteries together, then wrap with clear vinyl tape, then encapsulate with "plastic-dip". Where I ride, I usually have mud and water to fight. YMMV James


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## jaybee258 (Mar 26, 2010)

Hey guys, some great ideas here,- great reading. We have just lost a battery pack from a DX LED bike light, due to water in the protection circuit.. I like the idea of 'Plastic Dip'. What is that and how does it work?

I like the idea of just soldering the batteries together. So simple! Great if you can charge all your batteries together. I charge my batteries in pairs in a two way charger and plug it into an energy monitoring plug. The charger indicates fully charged after 2 - 3 hrs, but the charging current continues to decline for 6 hours giving a fuller charge. I guess this charger could be used with a group of 4 parallel batteries for a 5hr charge. I am interested to hear other views on charging. Reports of explosions makes me cautious, or are protected batteries safe? Charging batteries together in groups has got to be more dangerous as there will always be a weaker battery.

On the issue of inserting batteries the wrong way round, I guess protected batteries would help here. Does the individual protection just limit the current, or is it a safety fuse and renders the battery useless?

Has anybody tried out these holders yet at $20?

http://www.batteryspace.com/Battery-holder-Li-Ion-18650-Battery-Holder-1S4P-With-2.6-long-20AWG.aspx


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## scar (Jun 2, 2005)

That battery holder from BatterySpace is wired for 1 in series, 4 in parallel. Output will be 3.7 -4.2V.


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## El34 (Jan 11, 2009)

Plasti Dip is made to dip your tool handles into
Some sort of semi rigid plastic compound

I have dipped several 4x18650 battery packs and it works great.
Follow the instructions on the can.
you have to dip down and back up at a certain speed to make it coat and stick properly.

All my battery packs are 18650's solderin in parallel. 
The chargers I use all charge parallel packs just fine.
Even the cheapo DX chargers work great.

I have charged series/parallel packs without any problems on my fancy chargers


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## sdnative (Aug 10, 2008)

jaybee258 said:


> Hey guys, some great ideas here,- great reading. We have just lost a battery pack from a DX LED bike light, due to water in the protection circuit.. I like the idea of 'Plastic Dip'. What is that and how does it work?
> 
> Charging batteries together in groups has got to be more dangerous as there will always be a weaker battery.
> 
> ...


Yes, those DX packs seem to die fast.

Yes, I prefer to do single cells myself.

I have holders here that I think are much more flexible and can be wired exactly as you may need. You can read all about them here >>> http://forums.mtbr.com/showthread.php?t=544415

....price is cheaper to! :thumbsup:


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## Whitedog1 (Feb 3, 2009)

sdnative said:


> Yes, those DX packs seem to die fast.
> 
> Yes, I prefer to do single cells myself.
> 
> ...


thats correct sdnative, but you dont have a pcb installed on your holders!
With pcb's it would be much easier to charge the pack without beeing worried about burning them!


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## sdnative (Aug 10, 2008)

Whitedog1 said:


> thats correct sdnative, but you dont have a pcb installed on your holders!
> With pcb's it would be much easier to charge the pack without beeing worried about burning them!


But, that's what smart chargers and protected cells are for 

If you want to charge as a single pack, you then wire the holder for using a balance charger.

With the setup I run you have no chance of damaging your cells or anything else downstream, plus you get the benefits of more configuration options.


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## mike1980 (Nov 6, 2008)

sdnative said:


> But, that's what smart chargers and protected cells are for
> 
> If you want to charge as a single pack, you then wire the holder for using a balance charger.
> 
> With the setup I run you have no chance of damaging your cells or anything else downstream, plus you get the benefits of more configuration options.


+1

a smart charger as it makes it easy to spot a bad cell.


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## Whitedog1 (Feb 3, 2009)

I agree with the protected cells! great point - i missed that!

but i dont understand the part with the smart charger.?


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## mike1980 (Nov 6, 2008)

I used the wrong word, when I said smart charger I meant balance charger, I fail to see how a charger can be labelled smart if it isn't able to monitor individual cells.

A balance charger has balancing leads,ie. 5 leads for 4 cells the charger can 'see' each individual cell and therefore is able to individually top off cells so they all have the same voltage. As a bonus they usually have an lcd display so you can see individual voltages, level of charge put into the cells etc. The Turnigy Accucel-6 is a popular budget charger.

A regular charger can only see the battery as a whole so its possible the cells could have varying levels of charge ie. if three cells were at 4.1v and one at 4.2v then the charger would sense 16.7v and so keep charging despite one cell being fully charged.


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## Whitedog1 (Feb 3, 2009)

ok, now i am with you! It is like an rc hobby charger for the rc batteries - they all have this balance leads!

If I use some sort of holder and protected or unprotected 18650 cells i don't have this balance leads! - in this case it is easier to use protected ones...


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## jaybee258 (Mar 26, 2010)

Thanks guys, I have been looking for this info for ages. Great websites too, full of info help and good prices.

I am going for the 6 cell holder from sdnative because it will work in parallel with any number of cells that I have got charged up at the time. 4 will be normal use, but could use 6 on a long ride. Fantastic.

The modified charger from E134 is the biz. Charge single cells, or a group of cells together. Its all so simple when you know how.

Now that Plastidip must have a lot of uses too....

Cheers


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