About fuses and choosing the appropriate fuse for your mod

[icky]

Thank you for keeping us safe.

 

[brugmanncues]

@ EDog13 - the DNA30 has max input current 12A. If using 4x 18650 batts in parallel, you would use 1x 3A fuse per batt (12A / 4 batts = 3A).


@ sphongled1990 - the SX350 has max input current of 12A (actually 12.5A, but close enough to round it down to 12A). For 2x 18650 batts in parallel, you would need 1x 6A fuse on each batt, or 2x 3A fuse on each batt - your option to choose 6A fuse or 3A fuse.


@ StereoDreamer - the DNA30 requires a batt that has a minimum of 12 amps continuous discharge current to operate effectively.

The purple Efest IMR 18350 batts (I have no idea how good they are as I haven't used or tested them) are rated at 10.5A 700mAh.

Using 2x in parallel gives you 21A 1400mAh. So these batts would be suitable for your vaping needs with the dna. At 1400mAh, you will be getting very short vape time between charges though.

Alternately, you could use 1 Sony VTC5 18650 batt and have 30A 2500mAh for your vaping needs - larger current cushion and longer vape time between charges.

@Mamu, I just checked the specs on the YiHi SX350 50W, it's showing a Max Input Current of 25A now. I also am planning on doing a parallel 18650 build with this. I have (4) PTC RESET 6V LO RHO 2920 7.00A fuses. Would 1 of these fuses to each battery + be good, or would I need something else?

Thanks,

Nathan

 

[mamu]

@Mamu, I just checked the specs on the YiHi SX350 50W, it's showing a Max Input Current of 25A now. I also am planning on doing a parallel 18650 build with this. I have (4) PTC RESET 6V LO RHO 2920 7.00A fuses. Would 1 of these fuses to each battery + be good, or would I need something else?

Thanks,

Nathan

That's impressive that it can do 25A. I hope it has batt safety built in.

1x 7A fuse on each batt for parallel batts would only be 14A total. You have good protection, but may get annoying inadvertent tripping or partial tripping if the converter needs to pull higher than 14A. You could do 2x 7A fuses on each batt for a total of 28A. That's on the high side for that converter, but you still have good protection from catastrophic failure of the batts. I don't know what the internal overcurrent limit of the converter is, but might be better to use 2x 6A fuses on each batt for a total of 24A to protect both the converter and the batts.

 

[brugmanncues]

That's impressive that it can do 25A. I hope it has batt safety built in.

1x 7A fuse on each batt for parallel batts would only be 14A total. You have good protection, but may get annoying inadvertent tripping or partial tripping if the converter needs to pull higher than 14A. You could do 2x 7A fuses on each batt for a total of 28A. That's on the high side for that converter, but you still have good protection from catastrophic failure of the batts. I don't know what the internal overcurrent limit of the converter is, but might be better to use 2x 6A fuses on each batt for a total of 24A to protect both the converter and the batts.

It comes shipped unprotected, but by removing the black wire and soldering to another spot on the board it gives you reverse battery protection. The link to the sx350 specs is here: Yihiecigar SX350

Now when you say 2x 6A fuses on each batt, would that be the 2 fuses parallel or series for each batt?

 

[mamu]

It comes shipped unprotected, but by removing the black wire and soldering to another spot on the board it gives you reverse battery protection. The link to the sx350 specs is here: Yihiecigar SX350

Now when you say 2x 6A fuses on each batt, would that be the 2 fuses parallel or series for each batt?

parallel for each batt - stack one on top of the other with ends matching and solder together - do the same for the other set of fuses, then solder one set to each batt.

 

[dabunnny77]

So, I'm wondering, can more than two batteries be used. Say, 4 or 5 LiPo 1200mah. If so, I think 5 2.5a fuses on five batteries would be good, but which one, I only really understand being around 12volts for my DNA 30

 

[dabunnny77]

ok, I think I found the right fuses. running 5 batteries in parrallel. My question is would it be ok with a dna 30 to have the total Ihold be 12.5 or 13 or should i do 11. If I do 11 Amps, what are the disadvantages?

 

[dabunnny77]

ok, I think I found the right fuses. running 5 batteries in parrallel. My question is would it be ok with a dna 30 to have the total Ihold be 12.5 or 13 or should i do 11. If I do 11 Amps, what are the disadvantages?

So, I think i got the right ones, voltage adds up to 12.5 and everything else matches perfectly. its going to look crazy, 10 tiny fuses on 5 batteries, Ill post pics when its done.

 

[CraigTime]

For the DNA30, you would use 1x 6A fuse, or 2x 3A fuses, on each positive when using dual parallel batts.

Now I'm confused. I thought we should use two fuses in parallel? I'm building a dna30 mod and it will use one removable 18650 battery. A Sony vtc5. What/how many fuses do I need?

 

[mamu]

Now I'm confused. I thought we should use two fuses in parallel? I'm building a dna30 mod and it will use one removable 18650 battery. A Sony vtc5. What/how many fuses do I need?

For one batt you would use 2x 6A fuses.

 

[CraigTime]

For one batt you would use 2x 6A fuses.

Ok. Thank you!

 

[dabunnny77]

So, here is a pic so far. I Havnt gotten the craddle and screen holder, and I need to clean up the wiring but I couldn't help but put it together... Too much excitement to wait.

 

[mamu]

Well done and congratz with your mod, dabunnny!

 

[CenTexVpr]

So I am building a mech mod and will use 1 18350 battery. Want to use a pptc battery strap fuse as the positive contact. I had seen someone using this set up in the past. They stated they were using a 6 amp fuse. My question is was 6 amp the hold current or the trip current?

 

[wiizy]

I want to build a dual 18650 DNA 40 box mod
I need some suggestions for fuses
the Output Current, instantaneous peak is 23 amps
the Output Current, continuous is 16 amps
any help would be appreciated, thanks

 

[mamu]

For a fuse, you would look at the max Input current - which is 16A for the DNA40 and choose a fuse (or combined fuses) with a total Ihold equal to or close to that value.

If you're looking to use a fuse for reverse polarity protection, the DNA40 has reverse polarity protection, so if you're using a SINGLE 18650 batt, there is full reverse polarity protection for both the DNA and the batt.

If you're using DUAL 18650 batts, the DNA is protected from reverse polarity damage, but the batts are NOT. If you put one batt in correctly and the other batt in backwards, there will be immediate heat and then smoke and venting from the batts and possible fire from the short you created.

So for dual 18650 batt mods, the modder should provide some form of reverse polarity protection for the batts via either fuse that is capable of providing reverse polarity, or a P-FET on each batt.

Of the several fuses I have on hand that I tested for reverse polarity protection, I've found 2 that do protect:

LittleFuse smd 7A - 1x on each batt for dual parallel batts for a total of 14A Ihold - 2920L700SLPR

LittelFuse smd 4.5A - 2x in parallel on each batt for dual parallel batts for a total of 18A Ihold - 1210L450SLWR (these are uber teeny tiny and difficult to work with)

I haven't done extensive testing though with these fuses and TC mode with the DNA40 to see how compatible they are so don't know yet if will cause issues. I'm currently putting the DNA40 in a mod and am using the 7A fuse - 1x on each batt - and see how it goes.

 

[mamu]

Also, you need to pay attention to how you wire, as shown in the pic...

 

[wiizy]

For a fuse, you would look at the max Input current - which is 16A for the DNA40 and choose a fuse (or combined fuses) with a total Ihold equal to or close to that value.

If you're looking to use a fuse for reverse polarity protection, the DNA40 has reverse polarity protection, so if you're using a SINGLE 18650 batt, there is full reverse polarity protection for both the DNA and the batt.

If you're using DUAL 18650 batts, the DNA is protected from reverse polarity damage, but the batts are NOT. If you put one batt in correctly and the other batt in backwards, there will be immediate heat and then smoke and venting from the batts and possible fire from the short you created.

So for dual 18650 batt mods, the modder should provide some form of reverse polarity protection for the batts via either fuse that is capable of providing reverse polarity, or a P-FET on each batt.

Of the several fuses I have on hand that I tested for reverse polarity protection, I've found 2 that do protect:

LittleFuse smd 7A - 1x on each batt for dual parallel batts for a total of 14A Ihold - 2920L700SLPR

LittelFuse smd 4.5A - 2x in parallel on each batt for dual parallel batts for a total of 18A Ihold - 1210L450SLWR (these are uber teeny tiny and difficult to work with)

I haven't done extensive testing though with these fuses and TC mode with the DNA40 to see how compatible they are so don't know yet if will cause issues. I'm currently putting the DNA40 in a mod and am using the 7A fuse - 1x on each batt - and see how it goes.

you sir, are a gentleman and a scholar, thank you

 

[mberlinger3]

For a fuse, you would look at the max Input current - which is 16A for the DNA40 and choose a fuse (or combined fuses) with a total Ihold equal to or close to that value.

If you're looking to use a fuse for reverse polarity protection, the DNA40 has reverse polarity protection, so if you're using a SINGLE 18650 batt, there is full reverse polarity protection for both the DNA and the batt.

If you're using DUAL 18650 batts, the DNA is protected from reverse polarity damage, but the batts are NOT. If you put one batt in correctly and the other batt in backwards, there will be immediate heat and then smoke and venting from the batts and possible fire from the short you created.

So for dual 18650 batt mods, the modder should provide some form of reverse polarity protection for the batts via either fuse that is capable of providing reverse polarity, or a P-FET on each batt.

Of the several fuses I have on hand that I tested for reverse polarity protection, I've found 2 that do protect:

LittleFuse smd 7A - 1x on each batt for dual parallel batts for a total of 14A Ihold - 2920L700SLPR

LittelFuse smd 4.5A - 2x in parallel on each batt for dual parallel batts for a total of 18A Ihold - 1210L450SLWR (these are uber teeny tiny and difficult to work with)

I haven't done extensive testing though with these fuses and TC mode with the DNA40 to see how compatible they are so don't know yet if will cause issues. I'm currently putting the DNA40 in a mod and am using the 7A fuse - 1x on each batt - and see how it goes.

How should I go about fusing a 1s2p lipo that comes presoldered? I was thinking of a pair of 8A fuses on the positive bullet connector input to the board. Would this work or is that defeating the purpose? I want to stay away from soldering anywhere near the lipo.

Fuse link
http://www.digikey.com/product-detail/en/MF-R800-0-99/MF-R800-0-99-ND/2561470

Here's what the battery looks like (ignore the sx350)

 

[NaCl_H2O]

For a fuse, you would look at the max Input current - which is 16A for the DNA40 and choose a fuse (or combined fuses) with a total Ihold equal to or close to that value.

If you're looking to use a fuse for reverse polarity protection, the DNA40 has reverse polarity protection, so if you're using a SINGLE 18650 batt, there is full reverse polarity protection for both the DNA and the batt.

If you're using DUAL 18650 batts, the DNA is protected from reverse polarity damage, but the batts are NOT. If you put one batt in correctly and the other batt in backwards, there will be immediate heat and then smoke and venting from the batts and possible fire from the short you created.

So for dual 18650 batt mods, the modder should provide some form of reverse polarity protection for the batts via either fuse that is capable of providing reverse polarity, or a P-FET on each batt.

Of the several fuses I have on hand that I tested for reverse polarity protection, I've found 2 that do protect:

LittleFuse smd 7A - 1x on each batt for dual parallel batts for a total of 14A Ihold - 2920L700SLPR

LittelFuse smd 4.5A - 2x in parallel on each batt for dual parallel batts for a total of 18A Ihold - 1210L450SLWR (these are uber teeny tiny and difficult to work with)

I haven't done extensive testing though with these fuses and TC mode with the DNA40 to see how compatible they are so don't know yet if will cause issues. I'm currently putting the DNA40 in a mod and am using the 7A fuse - 1x on each batt - and see how it goes.

Great info - thanks!!