Topic: 9.6 V battery fuses

[johnw]

I've decided to put an in-line fuse between my batteries and my UA5. I did a search and couldn't find much other than it is reccomended. Saw pretty much the same thing on the "other" board. Before I go and screw things up, I wanted to make sure I have this right.

1) The fuse should be placed on the red (+) wire on the battery, not the adapt-a-cable.

2) The fuse should be an in-line replaceable or resettable type.

3) The fuse should be around 650 mA.

Would the following (slow blow .75) fuse work?

http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=270-1062

Or would this (fast .75) be better?
http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=270-1004

Would a blade style fuse be better? What stores in town would be likely to carry a blade style fuse or even better a resetable style that is between .5 and 1 amps?

[leegeddy]

>>I've decided to put an in-line fuse between my batteries and my UA5.

a very good idear.  no more BOOOM!

>>1) The fuse should be placed on the red (+) wire on the battery, not the adapt-a-cable.

yes. place the fuse inline closest to the power source.

>>2) The fuse should be an in-line replaceable or resettable type.

i prefer replaceable, personally.

>>3) The fuse should be around 650 mA.

the manual says the ua5 draws 450mA. i'd go with the lowest possible ampere fuse.

>>Would the following (slow blow .75) fuse work?

i prefer fast blow fuses.

>>Would a blade style fuse be better? What stores in town would be likely to carry a blade style fuse or even better a resetable style that is between .5 and 1 amps?

RS carries .5A blades and blade-fuse holders. they are cheap and are usually rated for lower voltage.

marc

[johnw]

I was thinking - if I add the fuse to the battery, won't the fuse blow every time I charge it? I'm using the rapid charger that does 3A in 90 minutes. Or does the positive current flow through the black wire when charging? Sorry if that's a dumb question - I obviously have no clue how battery charging works. I asked the guy at Radio Shack about this and he had no idea. He told me to just add it to he adaptaplug part. I told him that most people seem to add it to the battery.

[leegeddy]

>>I was thinking - if I add the fuse to the battery, won't the fuse blow every time I charge it?

i hope i'm following your description correctly.  i'm assuming that you have 2 pieces to the wire assembly.

you have a 9.6v RC battery that terminates in a molex type of a connection, right?

your charger terminates in the opposite sex connection. so when you're ready to charge, you just hook them up and let it charge.

your lead to the UA5 is a DC plug on one end and same sex plug (as your charger) on the other end.  you only have one place to splice in your fuse.... between the DC plug and the plug.  the fuse is not in the charging circuit.

>>I'm using the rapid charger that does 3A in 90 minutes. Or does the positive current flow through the black wire when charging?

equal amount of current flows through the entire circuit. what goes out must equal to what comes in.

>>Sorry if that's a dumb question - I obviously have no clue how battery charging works. I asked the guy at Radio Shack about this and he had no idea. He told me to just add it to he adaptaplug part. I told him that most people seem to add it to the battery.

no worries. it's good to be sure that your gear bag doesn't smoke at a gig!!

hope this aligns correctly.........

-O--------------------[    ]---------------->>              >>---------------------[[[[[[[]]]]]]]]]
dc plug                      fuse                     connector      connector                     battery

and you have your chager like this:

[[[[[[[[[[[]]]]]]]]]]]]]]]]]---------------->>
    charger                        connector

marc

[johnw]

Ok - I was thinking that the fuse should be between the molex plug and the battery casing, not between the molex plug and the DC plug. If I put a fuse on the battery, I was worried about the fuse blowing during charging. But if the fuse is on the DC plug end, then there is no fuse between the battery and charger.

[recordista]

Fuses are one of the many types of OPD (Overcurrent Protection Device) options available to you.  You need to differentiate between protecting your batteries and protecting your load(s).  If you're planning on disconnecting the two, they each need protection (from different things.)

Your electronics need protection against drawing more current than they can safely dissipate.  Something like the fuse you mentioned (I'd use a fastblow) is about right.

Your batteries need protection against a dead short across their output or from an internal short (or deep discharge) causing them to draw too much from a high current charging source.  PTCs (Positive Temperature Coefficient thermistors) are ideal for this.  They're not fast enough to protect sensitive electronics but are self-resetting, compact, and inexpensive--so you can bury them inside a battery pack and not have to worry about them.

Digi-Key carries several lines of  Raychem models that work well for this sort of thing.  I size them about 50% over the maximum safe charging current (or maximum load expected, whichever is larger) for the battery in question, so 4A for a typical 12AH SLA.

[rowjimmytour]

I just put my battery pack together for my UA5 and used a in line fuse w/ 5amp fast actin' fuse 250 volts. Well this do the job or should I buy another kind of fuse because I am confused on how to calculate volts>mA. Thanks in advance.
Peace

[leegeddy]

I just put my battery pack together for my UA5 and used a in line fuse w/ 5amp fast actin' fuse 250 volts. Well this do the job or should I buy another kind of fuse because I am confused on how to calculate volts>mA. Thanks in advance.
Peace

i'd switch out that 5amp for a much lower one, if i were you.  i can't recall how much current the UA-5 draws (under 1/2A, probably). so i'd go with a 500mA or 750mA fuse for better protection.

marc

[rowjimmytour]

I ended up changin' the fuse for a 1/2amp 250v fast actin' one. I hope this works because I just got orfered a new UA5 comin' friday!