Milo-DNA20D mod step-by-step how-to

[Chornbro]

If you are getting from Hobbyking they have a USA warehouse and the 2200mah are in stock there last I checked. You have to find the one that is marked USA warehouse. The 97mm is ONLY the grey foil area, the tabs are another ~10mm in length. But I believe you can fold them back along the pack to save some space; I would say 100mm is about as tight as you want to go for just the battery.

As for trusting these, there haven't been too many reports of well-built mods having problems with LiPo packs but they are inherently less safe than for example IMR batteries, and even ICR round cells because of their metal casing. The Groove's LiPo pack getting punctured was apparently the reason for the failures/fires.

As for whether Turnigy is a reputable brand, it is a low cost Chinese brand but it appears to be fairly well regarded. They do have the hobbyking contract which is apparently a pretty big thing. The RC guys run into their share of issues with Tunigies (and other LiPo brands) but their battery packs tend to see more physical abuse than ecigs would tend to see. For them, the hard case packaging makes sense, but even those can fail due to crash impacts.

In the end you are sacrificing some safety for price and power with any LiPo. But I believe most builders are at relative peace with that if they build well and put in their own safeguards (fuses, boards that have low voltage cutoff, chargers that work, etc.)

Awesome response, thank you! I think I'm going to go with the same batteries that Mamu used so that I can use the Hammond 1590 case.

Mamu, were you able to find the 2x 1200mah 25c lipos anywhere in the US?? Or did you get them from ebay/Honk Kong? $15 shipped for a pair... 3 weeks shipping... I can live with that.

 

[mamu]

I've bought these lipo batts for Milo and also Stealthy from this ebay seller and usually get them within a few weeks: rchobbyparts

These batts are aok, although I did get a few duds from the 2nd batch I bought. The 1st batch was aok and the 3rd batch was aok so reckon it's just luck of the draw.

I've also used the Storm lipo and helipal.com has fast shipping: Storm 3.7v 1200mah 25c lipo battery pack

It's cheaper if you buy the 7.4v pack and de-solder the pack and re-solder in parallel: Storm 7.4v 1200mah 25c lipo battery pack

The lipo batts I've had great results with are Spider (progressiverc.com - USA seller), Storm (helipal.com), Gens Ace (hobbypartz.com), ZOP Power (Hobbymate.rc - USA seller), and Turnigy (hobbyking.com - has a USA warehouse).

Just look for lipo batts that meet the height and width that you need and are also high drain. Lipo batts with low internal resistance are preferred, although you can't always find that info.

 

[Chornbro]

It's cheaper if you buy the 7.4v pack and de-solder the pack and re-solder in parallel: Storm 7.4v 1200mah 25c lipo battery pack

This is the route I ended up taking... Even though they're probably from China anyway, they're shipping from the US. $20 for 2400mah of LiPo juice... I'll take it! since these already have leads on them, I dont need the special aluminum solder/flux, correct? Like I would need if I were soldering directly onto the tabs??

Also, I forgot to pick up a charging board from Evolv... any objections to using this one? $6 will get me three of them... just in case : ) 1pcs Mini Lithium Battery LED 5V USB 1A Charging Board Charger Module | eBay

Also, the fuses are out of stock on mouser... can I pick these up locally? Elsewhere online? Radio shack or something? Searched the part number, no luck

 

[dr g]

That charger would be fine and is a great alternative to the Evolv board if you have the space and dont mind mini usb

 

[Chornbro]

That charger would be fine and is a great alternative to the Evolv board if you have the space and dont mind mini usb

Definitely wanting Micro USB... significantly more expensive... $7 shipped from China. Oh well =\

Is this adjustable charging feature difficult to use?

Went with this one.

http://www.ebay.com/itm/121126264728

 

[dr g]

I believe you would have to change one of the resistors on the board. but i don't see why you would want to do that anyway.

 

[Chornbro]

I believe you would have to change one of the resistors on the board. but i don't see why you would want to do that anyway.

Well, if I don't need to change anything, I'm not going to. This will be my first build, so this how-to thread seemed like a perfect fit. Relatively middle-of-the-road in terms of difficulty, but still a great looking and functional (hopefully) mod. Have a Darwin thats been my go-to for years. Love Evolv stuff.

Here's what I have...
Dna20, 2x 1200mah LiPos, Hammond 1590ABK, charging board, tactile switches, drill bits/press, soldering iron.

Need atty connector, finishing washer, fuses, wire, front cover, epoxy. Maybe a Dremel, although I might attempt this with hand tools. Missing anything?

Anyone know if I can get the fuses and wire at a local spot? Radio Shack maybe? They were sold out online.

 

[mamu]

Radio Shack carries hookup wire, but no PTC fuses. Any PTC fuse with around a 3A hold and 5-6A trip would be suitable for parallel - look for low resistance ones, or for one fuse look for around a 6A hold and 10-12A trip plus lowest resistance.

PTC fuses

I buy wire, heat shrink tubing, resisters, caps, etc at allelectronics.com

 

[Chornbro]

Radio Shack carries hookup wire, but no PTC fuses. Any PTC fuse with around a 3A hold and 5-6A trip would be suitable for parallel - look for low resistance ones, or for one fuse look for around a 6A hold and 10-12A trip plus lowest resistance.

PTC fuses

I buy wire, heat shrink tubing, resisters, caps, etc at allelectronics.com

Thanks, Mamu...

So, if running 2 in parallel...
http://www.digikey.com/product-detail/en/RGEF300/RGEF300-ND/1045838
or
http://www.digikey.com/product-detail/en/0ZRA0300FF1C/507-1304-ND/1560159

if running just 1...
http://www.digikey.com/product-detail/en/AGRF600-2/AGRF600CT-ND/3587521
or
http://www.digikey.com/product-detail/en/RGEF600/RGEF600-ND/1045834

Sorry for 21 questions... I'm out of my league when it comes to fuses. Safety is important to me, want to get it right!

Lastly, would 1 fuse cut it or do you recommend 2? 1 would be easier... but obviously you used 2 in your setup, so I'm guessing thats the preferred method...

 

[adventuredog]

Can one of you recommend a source for high quality F 510 connector? Thinking about rehoming the guts of a Vamo... which needs new threads.

 

[Chornbro]

Can one of you recommend a source for high quality F 510 connector? Thinking about rehoming the guts of a Vamo... which needs new threads.

Picked mine up at madvapes... All kinds of varieties.

 

[mamu]

Thanks, Mamu...

So, if running 2 in parallel...
Invalid Request
or
Invalid Request

if running just 1...
Invalid Request
or
Invalid Request

Sorry for 21 questions... I'm out of my league when it comes to fuses. Safety is important to me, want to get it right!

Lastly, would 1 fuse cut it or do you recommend 2? 1 would be easier... but obviously you used 2 in your setup, so I'm guessing thats the preferred method...

Any of the fuses you linked to are fine.

Two fuses in parallel doubles the hold and trip current, but halves the resistance. By halving the resistance the fuse minimally affects the circuit which is the primary reason for using 2 fuses in parallel. Another reason for using two 3A fuses in parallel, rather than a 6A fuse, is that they are smaller in size than a 6A fuse.

The 6A fuses you linked have lower resistance than two of the 3A fuses in parallel, so go for it if you want as you have the space in Milo for a larger sized fuse.

 

[Chornbro]

Thanks, Mamu! I went ahead and snagged a handful of the 6A fuses.

Looking at wire on allelectronics.com ... solid or stranded/braided?

 

[mamu]

Thanks, Mamu! I went ahead and snagged a handful of the 6A fuses.

Looking at wire on allelectronics.com ... solid or stranded/braided?

Doesn't matter solid or stranded - whatever you prefer to work with. Just remember to always apply a dab of flux then a dab of solder to tin bare wire ends. This will make soldering a connection to the wire more secure.

 

[Chornbro]

So... Flux, dab of solder to wire end, then dab of solder to make the connection to whatever else?

Special silver solder for the batteries? Or since they're already wired, use regular solder?

 

[billfirth3]

can you pm me the pdf for some reason I can't get it to load...please

 

[Chornbro]

Do you recommend flux even when using rosin core solder? 99.3 Tin/.7 copper

 

[mamu]

Sorry guys - I spaced that there were posts here that needed answering. Senior moments are getting too frequent lately.

So... Flux, dab of solder to wire end, then dab of solder to make the connection to whatever else?

Special silver solder for the batteries? Or since they're already wired, use regular solder?

Sometimes you need to solder to the side of the tab that has had no solder on it, so it's good to keep the aluminum solder on hand. Or, if you don't have it on hand, you could carefully scuff up the tab (I use a craft knife and carefully scrape the tip of the knife across the surface of the tab back and forth a few times), then solder the tab with regular solder.

can you pm me the pdf for some reason I can't get it to load...please

right-click on the file name, then click "save link as" to save the file to your computer.

Do you recommend flux even when using rosin core solder? 99.3 Tin/.7 copper

I use 60/40 rosin core solder and still always apply flux before soldering a connection. You will need to swipe a bit of flux across the pin holes of the DNA20D before soldering a wire into the hole in order to get a good connection - without flux applied to that hole you'll have problems.

 

[dr g]

FWIW I don't add additional flux and just go with the rosin core on the DNA20 holes, no problems yet. As long as you are getting a good joint it should be ok. But the flux might help some, I'll try some next time. Just not that keen on the need to wash it off.

 

[mamu]

There is some kind of poly coating over the entire board so I've had difficulty in getting a secure connection into and through the hole if I forget the flux. Just apply a dab of flux over the hole using the tip of a round toothpick just before soldering the wire in. No need to wash it off.