What size fuse for HEQ5 ciggie plug

[DarkKnight]

Hi all,

The specs say 11v to 15v DC 2amp (tip positive). I'll be powering it from a 38AH Gel battery.

I've asked this question elsewhere and been given conflicting advice. One poster said his mount kept blowing 2amp fuses and he uses 3amp with no problems.

Another poster recommended either a 5amp or a 7.5amp fuse which seems a bit  high to me, but then I am an electrical dumbo.

I don't want to fry my mount motors so I would really appreciate some definitive advice.

Thank you in advance.

[malc-c]

I use a 13.8v PSU with a digital display.  With both motors running in a slew and cameras running the current peaks as 1.2A, but my mount has a belt conversion.

If you want to fuse the supply try a 2A quick blow fuse, if that keeps blowing then fit a 2.5A.  But that's the issue, you want the fuse to blow in the event of an overload, so if the mount runs fine on a 2.5A fuse then increase the load by stalling the motors (prevent the scope from moving wilst slewing for a short while) and hope the fuse blows.  In normal tracking use the motors draw around 400ma, so if you then stall the mount the curent needs to exceet 2.5A to blow the fuse...

Best suggestion would be to get a cheap digital multimeter (anything from £5 upwards), and measure the current your mount draws, and then look for a solution that matches the needs.

[Alien 13]

I agree with Malcolm but even a correctly chosen fuse will still blow at some point due to fatigue, a useful addition is to fit a cheap volt/amp panel meter to the mount but it would require breaking into the cable.

Its also worth remembering too that in winter the inrush current to the mount will be greater.

Alan

[DarkKnight]

Thanks for the replies.

I'd like to know what fuse is in the factory HEQ5 cigarette socket plug.

[malc-c]

After a bit of googling, seems it's possibly a 5A fuse

http://stargazerslounge.com/topic/146527-important-prevent-your-eq6-board-from-frying/

[Lonestar70]

Hi Kev,

I can confirm it is a 5A x 1 1/4" quick blow fuse... just looked at mine.

Best regards.

Sandy.

[DarkKnight]

After a bit of googling, seems it's possibly a 5A fuse

http://stargazerslounge.com/topic/146527-important-prevent-your-eq6-board-from-frying/

Thanks. I must have been using the wrong search terms when 'googling' .

[DarkKnight]

Hi Kev,

I can confirm it is a 5A x 1 1/4" quick blow fuse... just looked at mine.

Best regards.

Sandy.

Cheers Sandy. 

Exactly the info I was hoping for. 

[malc-c]

Interesting that 5A fuses have been recommended.  I have a belt driven HEQ5 with an explorer 200P, ST80 guidescope and QHY5 camera attached.  The mount is powered from a bench supply with a digital Volt and Amp meter, and showed that when both motors were slewing it peaked at 1100mA (1.1A), with a constant draw of just 1A.  The RA drew 600ma when slewing, the DEC just 400mA. (the cameras were not being used, but the canon 400d draws 100-150mA at idle)

This is quite interesting compared to the old EQ5 that I had.  This would draw around 1.8A when slewing, with each motor drawing 900mA each.  Not sure if it was down to the gearing, or the motors that causes the current to be higher than the HEQ5.

Hope this info helps, and mabe fitting a 2A quick blow fuse would be a better option for an HEQ5.