About fuses and choosing the appropriate fuse for your mod

[Cotay]

So it seems that nobody has the 2920L700SLPR fuses in stock. Current lead times are listed at 13 weeks from Digikey.

Are there any other alternatives that folks recommend?

 

[Cotay]

An update on these fuses. I am assuming the original failure I had was due to overheating while soldering. I have now soldered about 8 in place without a failure. As you apply the solder you can actually hear the fuse "click" (It is faint, but audible if things are quiet) and I use that as an indication I cannot linger with the iron much longer and back off as quickly as possible. Still, I have kept applying the iron a few more seconds after the click without any more failures. After you are done soldering, the fuse will be "Open" due to the heat, but after 10 seconds or so (A little water bath helps too!) it will "Click" again and works just fine.

Also, I installed two on a dual battery sled and tested for reverse polarity protection. Inserted one battery upside down and then connected the negative tabs of the sled - almost immediately "Click" and resistance through the fuse jumped very high - remove the connection from the negative tabs and another "Click". Even had instances when both fuses would open. Also left the batteries in this state for a longer period (60+ seconds) and they returned to normal operation.

That's my experience with them anyway!

Which version/part number are you using. I see that Digikey has several of them with different operating temperature ranges.

 

[NaCl_H2O]

Which version/part number are you using. I see that Digikey has several of them with different operating temperature ranges.

I used the MHP-TA15-9-77
RF2825-000 TE Connectivity | RF2825-000-ND | DigiKey

 

[ozen]

I used the MHP-TA15-9-77
RF2825-000 TE Connectivity | RF2825-000-ND | DigiKey

I use the same fuse and easy to work with compare to 2920L700SLPR

 

[Cotay]

I used the MHP-TA15-9-77
RF2825-000 TE Connectivity | RF2825-000-ND | DigiKey

Thanks! I'll pick up a dozen or so of these for my several builds.

 

[david4500]

6 amp version of the TE strap fuse:

MHP-TA6-9-85 TE Connectivity / Raychem | Mouser

 

[Cotay]

6 amp version of the TE strap fuse:

MHP-TA6-9-85 TE Connectivity / Raychem | Mouser

What's the advantage? I am by no means an expert with fuses, but I thought the 15A hold current of the MHP-TA15-9-77 TE Connectivity / Raychem | Mouser would be better for a DNA40. At least you only need one instead of two of them per battery, correct?

 

[studiovap]

I used the MHP-TA15-9-77
RF2825-000 TE Connectivity | RF2825-000-ND | DigiKey

has anyone found the trip times for this one? all the data sheets are kinda incomplete from my searches. I am looking at using them for a single 18650 mosfet build, as they are much cheaper than 2 in parallel of the littlefuse 7A, and also easier to source, but the speed of trip is important, some of these PTCs are 5plus seconds and surely damage will be done by then in my mosfet build.

 

[NaCl_H2O]

has anyone found the trip times for this one? all the data sheets are kinda incomplete from my searches. I am looking at using them for a single 18650 mosfet build, as they are much cheaper than 2 in parallel of the littlefuse 7A, and also easier to source, but the speed of trip is important, some of these PTCs are 5plus seconds and surely damage will be done by then in my mosfet build.

In my reverse polarity testing (two batts) the trip time was almost immediate. I did not do any testing to attempt to exceed the 30A trip current.

 

[studiovap]

My research has led me to believe that the MHP-TA15-9-77 is not a fuse as such, but a thermal sensing cut off, the link below seems to support this, so how effective is it for our quick trip needs?

http://www.batterypoweronline.com/conferences/wp-content/uploads/2013/06/TE.pdf

 

[david4500]

With a mosfet mod with those fuses, I've intentionally shorted the 510. The fuses stop the current flow just about immediately.

In the event of overcurrent/short, the fuses will heat up and trip at their thermal rating. Removing that fault, the fuses will cool and allow the current to flow as normal.

 

[studiovap]

With a mosfet mod with those fuses, I've intentionally shorted the 510. The fuses stop the current flow just about immediately.

In the event of overcurrent/short, the fuses will heat up and trip at their thermal rating. Removing that fault, the fuses will cool and allow the current to flow as normal.

Just read your posts on the BT forum, thanks David