Fuses Blowing

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29 November 2013 at 11:28 #45303
Tim Cooper
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@timcooper90034
Can anyone offer advice about blown fuses?

I took my Model Slipway Tamar for its second run the other day, everything was going well, just doing a big turn in the middle of the pond when everything stopped. No power at all! Unfortunately my recovery device (tennis ball on a fly fishing line) failed but the park attendant had some waders I could borrow. Back home I found the 25 amp fuse on the Action Power Board had blown. All the other fuses on the board and around the boat (15 amp) were Ok.

The set up is 2 x 600 motors, 35mm brass props, and 2 x 9.5 v batteries in parallel.

Am I looking for a short circuit ? The batteries were freshly charged but I had no problem a few weeks before, and I had already completed a maximum speed run on this day.

I wonder if I might be better changing the batteries to 2 x 8.4v packs?

Thanks

Tim
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29 November 2013 at 11:28 #5281
Tim Cooper
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@timcooper90034
29 November 2013 at 11:36 #45304
Dave Milbourn
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@davemilbourn48782
Replace the 25A fuse and check that everything still works as it should. Which type of 600 motors have you fitted?

Dave M
29 November 2013 at 17:37 #45308
Malcolm Frary
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@malcolmfrary95515
While a fuse blowing usually indicates a problem to be found and fixed, they can just get fed up and die. If you can grab a high current meter (car ammeter from a scrapyard in the old days, when you could get such things), finding out just what current is being taken is generally a good thing.

If one of the 15A fuses was passing current at its max, while its mate was taking rather less, the weak link would be the 25A one, carrying the total of both others.
30 November 2013 at 14:05 #45312
Tim Cooper
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@timcooper90034
I have changed the 25 amp fuse and everything seems to be working Ok. Haven't had the boat back in the water yet.

The motors are Graupner 600 ECO supplied by Model Slipway with the kit.

Tim
30 November 2013 at 14:25 #45313
Dave Milbourn
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@davemilbourn48782
These motors are rated at 7.2v and so you may have momentarily exceeded the combined current consumption. While I wouldn't recommend using a 30A main fuse if you choose to do so then there's not much I can say………….

I recommend Speed 700BB Turbo 12v motors for this model. They will turn a 4-blade scale brass prop easily (40mm dia). Part # is G6317 and they are currently in stock at Gliders of Newark. **LINK** You might also try A Model World who are usually cheapest for Graupner items. Knock three times and say Dave sent you……………….

DM

Edited By Dave Milbourn on 30/11/2013 14:26:12
30 November 2013 at 16:46 #45315
Tim Cooper
Participant
@timcooper90034
Thanks Dave

Not sure I like the 30 amp fuse option either. That might just produce a fire in the middle of the pond! Although I have a Robbe Dusseldorf Fire Boat! I will have to get motors on the Xmas list.. Is dropping down to 8.4v Power packs another option?

Thanks

Tim
30 November 2013 at 19:10 #45318
Dave Milbourn
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@davemilbourn48782
It's not a bad idea but it will cost more than a 30A fuse (which would blow if there were to be a repeat performance). You could go back to using the plastic props which came with the kit; they will be a finer pitch than the brass ones.
A neater idea would be to fit an on-board watt-meter to monitor just how much current the motors are drawing. It may be that this was an isolated incident e.g. weed.
I'm convinced that the motor change will do the trick, although you'll need some 12v packs (3S LiPo).

Fun, this hobby, innit?

DM
1 December 2013 at 10:40 #45324
Tim Cooper
Participant
@timcooper90034
Thanks Dave

I might try to find the plastic props that came with the kit. My wife says she will buy me some waders for Xmas just in case.

Do you think the brass props would be Ok with Graupner 600 Turbo (I think) 12v I have fitted to the Berrnhard Gruben I'm building at present. These will run from 12 v SLA batteries?

Tim
1 December 2013 at 13:06 #45328
Dave Milbourn
Participant
@davemilbourn48782
Tim

The 12v Speed 600 BB looks way too fast for any sensible scale props without a gearbox, and they're not much cheaper than the 700 ones I would recommend. I always advise folk to avoid using SLA batteries in a performance hull – L stands for lead! Use NiMH or LiPo packs for light weight and current output.

Dave M
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