Easy OKR-T VV mod

[mv2envy]

Im having a little problem. I just finished my dual 18650VV using the 6A chip and my adjustability range jumpts from 7.1V to 8.2V. What did I do worng? The wiring matches the diagram on the first page to the T! Wrong pot or resistor maybe? I ordered fromt he links on page 1.

 

[bstedh]

Im having a little problem. I just finished my dual 18650VV using the 6A chip and my adjustability range jumpts from 7.1V to 8.2V. What did I do worng? The wiring matches the diagram on the first page to the T! Wrong pot or resistor maybe? I ordered fromt he links on page 1.

Are you able to post a clear picture of your board and wires? that would help a lot. The problem I had was a short in one of the wires going to my POT. I would do a continuity check between all the connection to make sure you don't have a short to ground somewhere. Also with an ohm meter check the resistance between ground and pin 5 as you change the pot setting and compare that against the voltage range on the spec sheet also posted somewhere in the thread here.

 

[mv2envy]

Nevermind I'm an idiot. I used a small interconnect board to mount the pot and resistor and forgot to cut the contact between the 2 legs of the resistor. It was as if the resistor wasn't there. Fixed now.

One more question please Is there a charging board I can buy that will charge 2 batts at the same time? My mod has a screw on cover so it will be a pain to charge the batts every night. I have only found charging boards for single cell applications on eBay.

 

[unloaded]

I couldn't find a board but you might be able to make something like this work:
Customize Smart DC Charger for 7.4V Li-ion Battery Pack with 5.5x2.1mm male barrel connector

 

[bstedh]

Nevermind I'm an idiot. I used a small interconnect board to mount the pot and resistor and forgot to cut the contact between the 2 legs of the resistor. It was as if the resistor wasn't there. Fixed now.

=] someone else just did the same thing over on the evercool post....

 

[bstedh]

I couldn't find a board but you might be able to make something like this work:
Customize Smart DC Charger for 7.4V Li-ion Battery Pack with 5.5x2.1mm male barrel connector

Would something like that work with protected batteries or would you need un-protected batteries to get it to charge correctly?

 

[mv2envy]

That charger could work but I would really like to do a built in USB charger. Much more universal that way. But if I cant find another way, I guess ill order one of those.

 

[mv2envy]

Found more info on that charger. Seems like it will work just fine. All I'll need to do is fit a barrel charge port from radio shack and I'll be set. Thanks!

Customize Smart DC Charger for 7.4V Li-ion Battery Pack with 5.5x2.5mm male barrel connector

 

[meatsneakers]

I use that charger for the mod I posted a few posts up and it works great on protected batteries.

 

[bstedh]

That charger could work but I would really like to do a built in USB charger. Much more universal that way. But if I cant find another way, I guess ill order one of those.

USB will not work. USB=5V and you need 7+ to charge batteries in series. Even than you want about 8.4V at the top end for fully charged batteries.

 

[mv2envy]

Just placed an order for that charger. Thanks.

 

[mv2envy]

Here is the finished product. A HUGE thanks to Mamu, the creator of this post (OP) and everyone els who helped!

Specs

Voltage range Im getting is 3.7V-6.5V

Radio Shack 1"X2"X4" Project box
2 AW 2900mah protected batteries
6A OKR-T regulator, Pot and resistor from the first post
Battery posts are from a dual size C battery holder from Radio shack
Voltage display from madvapes <---Works well!
Horn Style style switch from madvapes <------More on this piece of .... later!
threaded 510 adapter from madvapes <----pricey!!!!

Its not done yet. I still have to add a external charging port, a LED and replace that stupid ....ing switch with one that works every time I press it! And one that doesnt stick into the case as much. Do yourself a favor and dont buy this switch from mad vapes, its really cheap and will break in no time. Mine did.

Here are the pics, please let me know what you think

And one next to my brand new Reo Grand which came today

 

[mamu]

Sweet mod mv2envy!

LOL - I didn't create the "OKR-T" - bstedh and CapeCad shared the module and the wiring with us.

 

[mv2envy]

I replaced the defective switch, and added a led. The switch now sits flush on the box too.

 

[Rocketman]

That is a really nice looking mod. The box looks quite sturdy compared to a lot of snap together boxes.

I'll offer one comment.

The switch terminals appear to be very close to the cell. maybe an additional layer of insulation or a little protective epoxy to keep the cells from wearing a hole in the wrapper against the bare terminal.

Nice job on the mod.

 

[mv2envy]

Thanks Rocketman. I placed a piece of cut postcard between the terminals and the cell so they are not touching. I did that after the pics.

 

[Sinlak]

This is freaking sweet, once I got the cash for my tools im going to try and build this in an altoids can. Where would you hook up a Battery Voltage Indicator in this diagram?

 

[mv2envy]

You can hook up a voltage indicator and a LED if you wish to the 2 leads going to the atty connector.

 

[bstedh]

This is freaking sweet, once I got the cash for my tools im going to try and build this in an altoids can. Where would you hook up a Battery Voltage Indicator in this diagram?

It mostly depends on which voltage you would like to measure. If you are using the MV MM you have I believe 6 different measurements you can take. So you can measure each cell, cells combined, and atty output.

For basic output measurement you would go from battery negative to atty positive.

 

[jamess71]

Great thread and Beautiful mods. mv2envy, I love it. just add a charging circuit and I would call it the Ultimate Mod. ;-)