trim/tilt switch = engine power loss?

DonMacN · 27 July 2009, 22:15

couple of questions on electronic trickery! Sorry for the long lead-in (no pun intended

) but better to provide enough information I think.

I have recently (50hrs running hours) had a new 90hp installed. It came with 2 metre battery/power cables, not long enough to reach the battery so had to be extended by about another 2 or 2.5m.

This was done by getting extension leads properly made up by an electrical supplier with ring ends, then bolting these to the ring ends on the ones from the engine and trying to waterproof the joins with rubberising tape. This was how the old engine had been installed, so seemed like a fair enough approach.

So - problem started to develop between operating trim/tilt and the engine. If I used the switch the engine power died right away. It didn't stall or stop, but dropped away to nothing momentarily. As soon as the t/t switch was released, power came back on stream. Then, while out last week, engine just died completely, no power to starter, no power to t/t. Had to use the donkey to reach an alternative slip.

On the phone Honda had suggested a possible current loss to the engine, given the size of the t/t motor and its current draw, so I stripped the new cables out of their ducting and found that unfortunately the rubberising tape on the power leads was a cheap version or something because it seems to have worn away slightly on the bolt tops - there was never metal-to-metal contact - but it's possible there was sufficient moisture or salt build up to allow a current leakage. I dried and resealed the joins with loads of black vinyl tape (temporary only I hope) and it's all worked fine since. Happy - except for a mate who's a qualified mechanic who reckons a 12v system would never short out like this without being more 'spectacular' in terms of smoke/fire etc. Any thoughts??

Possibly related has been that my radio kept blowing fuses. Should be 3amp, but I'd had to go up to 7.5amp in stages and it was still going. The 'accessory' side of the battery is wired roughly in parallel, and the fuse to the radio was the 'first' one - ie shortest + to - route. If there was some sort of arcing going on with the main leads would this generate a power surge that might blow such a fuse??

At the moment all my 'accessory' wiring has been stripped out to see how the engine and t/t behave, and so far it's all going fine. Now need to re-introduce stuff to see if it works again.

Anyone know if Honda supply longer one-piece power leads as an option? Joining cables on the deck of a RIB used for diving really doesn't seem like such a good idea..

Thanks for any help.

Nos4r2 · 27 July 2009, 23:33

Quote:

Originally Posted by DonMacN

couple of questions on electronic trickery! Sorry for the long lead-in (no pun i---------------------------------------------------

Thanks for any help.

You've probably got a bad contact on the main battery lead to the engine where it was joined or at the join or the battery terminal.Disturbing it has probably improved the contact temporarily.

Is it soldered by any chance?

Your mate is right btw.

DonMacN · 28 July 2009, 08:11

cheers Nos,

The connections at the cable joint are new ring connectors bolted firmly together with an M8 bolt. They feel fine, no movement, and reasonably well-protected. I reckon they're OK.

THe ones at the battery are (from memory) those terminals where you insert the cable and then use two screws to hold it in place. Again, new stuff. That's no guarantee I guess.

I'll check them all again, but, if you don't mind my asking, why do you suggest this? Would this also = power surges affecting the accessory side??

doggypaddle · 28 July 2009, 09:40

A bad connection on the battery can cause all sorts of problems, depending on the type of alternator you have, if your battery becomes "out of circuit" due to a poor connection on the terminal then the voltage on the cables can "spike" causing fuses to blow, or your regulator to fail, then you will get overcharging and high voltages.
The worst case scenario is you have an alternator without a regulator,(smaller O/Bs only) these rely on a reasonably high internal resistance to limit the charge current into the battery to a sensible amount, the low resistance of the battery then keeps the voltage down at 12-15 volts. the alternators are designed to output 14 volts at about 1000 rpm so the battery charges at tickover, output voltage is proportional to RPM so at 4000 rpm the voltage with no battery attached could be as high as 50 volts, your radio wont like that

so in a word YES!

Ditch the jointed cables, any joint is a potential point for water to get in, replace them with some tinned welding cable 25/35mm sq with the crimp ends soldered on and sealed with self amalgamating tape or glue filled heat shrink (both ends) then put the loop through the battery terminal bolt. i prefer not to use the pinch screws, after a while water gets up the cable and turns it into a green corroded resistor

Nos4r2 · 28 July 2009, 11:27

^^^

What DP said...

However, I wouldn't solder the crimp ends on-vibration and a salty atmosphere does odd things to solder and self-amalgamating tape isn't a garuantee of a perfect seal forever.

I'd dip the cable in vaseline then just crimp it on using proper hydraulic crimps before using self-amalgamating tape on it.

doggypaddle · 28 July 2009, 11:46

I should have mad myself more clear.......crimp the ends on then solder! just to fill the gaps in. good quality solder is fairly impervious to salt water, what causes problems usually in my experience is not using tinned wire,
the lead solder copper interface creates a galvanic cell and corrosion sets in, if the wire is tinned this cant happen. Glue filled heat shrink is good to use and vaseline by the bucket load

jyasaki · 28 July 2009, 16:43

Your VHF fuse problem is a red herring, assuming it's a fixed mount unit. A 25 watt VHF will draw 5 to 7 amps (or possibly more) when transmitting on high power. If you had a 3 amp fuse, well, there's that problem. Look in the users manual and fuse it appropriately. If it blows again, then you can say there's another cause.

For the battery thing, I always try to minimize electrical connections between high-current things. A little resistance due to looseness, corrosion, or whatever will drop a lot of voltage. A loose gound does all kinds of wacky stuff (and can, in some instances, damage the alternator assembly.)

Might spend a bit and do it up right in a single run. (sorry, just noticed doggypaddle said the same thing.) Skimping versus doing it right often leads to spending more to correct problems.

jky

DonMacN · 28 July 2009, 17:28

thanks gents.

I had thought to replace the power cables with a single run. Checked with my dealer today and Honda don't supply this part. They have given a spec. for the cable though (which doesn't mean an awful lot to me at this stage!). I'll need to google: "AV20, 170amp, flexible moulded twin-core. 350/0.30mm, OD9.5mm, X-section/Core 75mm2, 170amps." I think the second sentence says more or less the same as the first? Any ideas of suppliers, or is the tinned welding cable to the same spec.?

On the radio side, I did also wonder if it was a 'red herring', however.... I definitely did check the manual during the installation, and I' certain I'd have used the correct rated fuse (I'm not that daft, am I??

. However I've just checked the Standard Horizon website, and for that model it does say it draws 5.5amps when transmitting on High. I've also got the remote mic and an additional speaker connected, all of which probably do push up the draw a little. However, however, the fuse has also gone when I haven't been transmitting..... It may even have gone the last time when the radio wasn't even switched on.

Just can't be certain of that because the radio's fixed inside the console and usually operated with the remote mic.

DonMacN · 28 July 2009, 17:39

hmm.
Just googled that cable spec and it seems to maybe be AV20, 170amp, flexible moulded twin-core. 350/0.30mm, OD9.5mm, X-section/Core 25mm2, 170amps??

The original one on the engine is a nice twin moulded thing - can't seem to find that on the web - though maybe that's too much to hope for... sure it doesn't make any difference to its function - indeed maybe a red one and a black one is a much better idea.

doggypaddle · 28 July 2009, 18:59

Quote:

Originally Posted by jyasaki

Your VHF fuse problem is a red herring, assuming it's a fixed mount unit. A 25 watt VHF will draw 5 to 7 amps (or possibly more) when transmitting on high power. If you had a 3 amp fuse, well, there's that problem. Look in the users manual and fuse it appropriately. If it blows again, then you can say there's another cause.

jky

unless the loose battery terminal fecked the alternator and the voltage is going above the safe limit for tha radio, triggering a voltage crowbar on the input to the set blowing the fuse? some good quality 12 volt kit will have a crowbar that shorts the input at say 18 volts to blow the fuse and save the set. if you see what i mean.

jyasaki · 29 July 2009, 17:02

I do understand, doggy.

Would make more sense to simply kill power if it exceeds the input limit, though (which I think is a more normal design these days. Saves wiring.)

OP said he was using a 3 Amp fuse, and it blew. There was a reason for that (wrong fuse). Get things set up right, then start troubleshooting. That was all I was saying.

If the fuse blew with the VHF off, I'd carefully check wiring after the fuse but before the radio. The current that blew the fuse had to be going somewhere.

jky

doggypaddle · 02 August 2009, 22:17

Quote:

Originally Posted by jyasaki

I do understand, doggy.

Would make more sense to simply kill power if it exceeds the input limit, though (which I think is a more normal design these days. Saves wiring.)

OP said he was using a 3 Amp fuse, and it blew. There was a reason for that (wrong fuse). Get things set up right, then start troubleshooting. That was all I was saying.

If the fuse blew with the VHF off, I'd carefully check wiring after the fuse but before the radio. The current that blew the fuse had to be going somewhere.

jky

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