Bison 55 electric outboard review

[MINESAPINT2]

Bought one about 18 months ago and used it with 85 amp battery - no problems. Bought a new 110 amp battery and the outboard failed within a week. Phoned fishing mad who advised the switch will have melted due to using 110 amp battery (apparently other users have experienced same problem). However the instruction manual stated battery requirement as "minimum 50 amp". I bought a new switch and fishing mad also supplied a thermal circuit breaker to reduce the chance of this happening again. Fitted switch and everything seems OK but not been on the water. Interested to see what happens when afloat as maximum power consumption is 52 amp and circuit breaker is 50 amp. I suggested to fishing mad perhaps I should not use maximum power (5th speed) but they say this should not be necessary. They did say they do not recommend a battery bigger than 85 amp despite the instruction manual stating minimum 50 amp and also said had I used a 200 amp battery the switch would have fried much sooner. When I carried out the repair I could see the switch had indeed melted, it is a pity the switches are not made from a more suitable grade of plastic although I have to accept these outboards are cheap as chips so perhaps I got what I paid for.

Minesapint

 

[Murv]

Interesting. I was thinking yesterday that I'm quite impressed with mine.
I bought a real cheapy thing off ebay a few Years ago, but it failed quite early on leaving me with a long paddle back against the tide. All the paint dissolved from the motor as well and it looked as if it was falling to bits.
Not wanting to pay Yamaha etc money, I went for a slight upgrade with a Bison (63 or 65) a couple of Years ago and it's been absolutely fine. The clamp screws need regular greasing, and I noticed yesterday that the paint is just starting to lift where the shaft clamps to the motor, but it's faring pretty well considering it just gets slung in the shed after each use.
I do use a 85AH battery though as it's what I had.
As you say, cheap as chips so if it failed tomorrow, it owes me nothing.

 

[RupertW]

How does the amp hours of a battery make any difference to current that flows - the engine sounds very badly designed if it can draw enough power from a 12v battery to make anything melt or fail. It could fry something equally from a 20ah bank as from a 600ah bank, surely?

 

[Kelpie]

That's what I was thinking as well- it's like saying your engine failed because you hooked it up to a larger fuel tank. Weird!

How many hp is one of these motors equivalent to?

 

[JumbleDuck]

How does the amp hours of a battery make any difference to current that flows - the engine sounds very badly designed if it can draw enough power from a 12v battery to make anything melt or fail. It could fry something equally from a 20ah bank as from a 600ah bank, surely?

That's what I was thinking as well- it's like saying your engine failed because you hooked it up to a larger fuel tank. Weird!

How many hp is one of these motors equivalent to?

Maybe a smaller battery shows a bigger voltage drop at full power?

 

[Murv]

How many hp is one of these motors equivalent to?

There are conversions you can do online, but they're pretty feeble compared to a petrol.
My 63/65lb thrust pushes a 10' tender against the tide at a reasonable pace, maybe 3 knots or so, so possibly 1hp, something along those lines?

 

[MINESAPINT2]

Maybe a smaller battery shows a bigger voltage drop at full power?

I was confused about this and guessed the 85 amp battery could not maintain the full power of 52 amps for long enough to damage the switch. I guess the 110 amp will provide 52 amps for a longer period on full power. However I noted when I fitted the new switch that the spade terminal in the vicinity of the melted plastic was a fairly loose fit, all the others needed a good push to get them on. I should make clear that the owners manual for this motor recommends the fitting of a 50 amp circuit breaker which I did not do until now. Perhaps this would have saved the switch had I carried out the recommendation from the outset.

Minesapint

 

[lpdsn]

Sounds like he was just making it up. And there's a lot less polite way of putting that.

Seriously, his assertion effectively is that the product will only work at the specified voltage for a short period and relies on a voltage drop caused by the draining of the battery for safe operation with vitually no margin in the design for that criteria being exceeded. God knows what effect he'd claim ambient temperature would have. Maybe even a high CCA would be fatal.

Much more likely there was just a fault.

However, they'd have a valid point about a circuit breaker. Can't see that that would do much more than limit the damage though.

 

[lw395]

I was confused about this and guessed the 85 amp battery could not maintain the full power of 52 amps for long enough to damage the switch. I guess the 110 amp will provide 52 amps for a longer period on full power. However I noted when I fitted the new switch that the spade terminal in the vicinity of the melted plastic was a fairly loose fit, all the others needed a good push to get them on. I should make clear that the owners manual for this motor recommends the fitting of a 50 amp circuit breaker which I did not do until now. Perhaps this would have saved the switch had I carried out the recommendation from the outset.

Minesapint

I would think that the loose switch contact was not making proper contact. A bit of resistance and so it gets hot and gets worse. You don't need many amps for this to happen.
At these currnets, all the contacts need to be properly tight and clean.

The capacity of the battery is not important. My motorbike battery is only 6Ah, but it chucks out 90A for a short while.

If it's taking 52A at 12V, that's 624W. If it was 80% efficient, that would be 2/3Hp.

 

[Tranona]

.

If it's taking 52A at 12V, that's 624W. If it was 80% efficient, that would be 2/3Hp.

The problem is that even if the motor is producing that power it is not converted into thrust because of the small high speed prop. Good for mixing your cocktails quickly but not for pushing a heavy flat bottomed dinghy. On the other hand an Seagull with low power output but a big slow turning prop will do the job.

 

[lw395]

The problem is that even if the motor is producing that power it is not converted into thrust because of the small high speed prop. Good for mixing your cocktails quickly but not for pushing a heavy flat bottomed dinghy. On the other hand an Seagull with low power output but a big slow turning prop will do the job.

Some truth in that, but I think it the OP's view, it does the job?
No propellor is every 100% efficient, how small are the Bison props? Much smaller than a Yamaha 2hp prop?
One horse will move a canal barge much faster than either a Yam 2 or Seagull I think.
An actual bison might be better still, but only if there's a towpath.

 

[MINESAPINT2]

Does anyone know the amperage rating of these outboard motor control switches, apparently they are used by lots of manufacturers. Additionally they have 6.3mm? (old one in the shed, will measure later) blade connectors, does anyone know the amperage rating for a 6.3mm blade.

Minesapint

 

[MINESAPINT2]

There are conversions you can do online, but they're pretty feeble compared to a petrol.
My 63/65lb thrust pushes a 10' tender against the tide at a reasonable pace, maybe 3 knots or so, so possibly 1hp, something along those lines?

Just found a statement on line

1hp is equivalent to 550lbs of work per second. Although they say there is no direct comparison.

So I guess my 55lb outboard is one tenth of a horsepower?

No doubt it is feeble compared with a 2hp outboard and is much heavier when the weight of the battery is taken into account but given 2 identical dinghys I would not be able to keep pace with the electric powered outboard with a set of oars.

Minesapint

 

[Murv]

Just found a statement on line

1hp is equivalent to 550lbs of work per second. Although they say there is no direct comparison.

So I guess my 55lb outboard is one tenth of a horsepower?

No doubt it is feeble compared with a 2hp outboard and is much heavier when the weight of the battery is taken into account but given 2 identical dinghys I would not be able to keep pace with the electric powered outboard with a set of oars.

Minesapint

That's interesting, guess I was way off then! I suppose it's the issue of once you've reached hull speed of a displacement dinghy, then more power isn't much help.
My little 2.5 is certainly a bit faster, but it's just so much easier with the electric one.
I always used to row to my mooring, but after a particularly eventful journey against a strong wind and tide (45 minutes of rowing for a 1/4 mile journey) I switched to a motor!
I was working on the boat on Monday, coming back against the near gale and a strong tide was absolutely no issue at all for the bison. I wouldn't have even tried it if I only had the oars.

 

[cpedw]

Just found a statement on line

1hp is equivalent to 550lbs of work per second. Although they say there is no direct comparison.

I should lose that online source.

Horsepower is a measure of power in the same way that Watt is. One HP = 746 Watt.

The original definition of HP is 550 foot.pounds/second so a force of 550 pounds moving at 1 ft/sec is exerting 1 HP. If it goes faster, the force of 1HP goes down e.g. 55 pounds at 10 ft/sec is also 1 HP.
More simply, a force of 1 Newton moving at 1 m/sec is exerting 1 Watt.

Electrically, 1 Volt at 1 Amp is 1 Watt but putting an electric Watt into an outboard will be sure to get less than 1 mechanical Watt out to the dinghy.

Derek

 

[JumbleDuck]

The original definition of HP is 550 foot.pounds/second ...

Watt himself did measurements on the work output of horses, and concluded that the average horse could keep up 22,000 ft-lb per minute. He then bumped that up to 33,000 ft-lb per minute (your 550 ft-lb per second) so that purchasers of an "8hp" (say) Boulton & Watt engine would be pleasantly surprised at how much better it was than eight horses.