Electricery

[Randonneur]

This is a trolling post  

I'm thinking of adding a trolling motor to the Paradox as I hate carrying smelly, inflammable petrol on board and a dead weight on the transom.

In my quest for something off the shelf, I'm overwhelmed with choice.
So I call on the great and wise, particularly Pauly and Alistair, to chip in with some numbers that I can base my search on.

What motors do you have (lbs thrust). What capacity battery do you have and what is the typical range on eg the Thames raid.
For Paul.  What ESC do you use and what difference does it make to efficiency and run time.

I'm also considering 50 -100 W of Solar with MMPT, to see me through the summer.

The motors I've looked at are from dirt cheap to eye wateringly expensive, like the Minn Kota Riptide 55 Saltwater.
Whilst a marinised motor would seem best if regular use was made in the briny, I foresee more regular usage of the motor in fresh water, and a good rinse after use if I have to use a freshwater unit in the sea. Does that seem like a fair compromise until I'm sure this is the way forward (and astern)?

TIA

[Paul H (admin)]

Pete,

Lets assume the Paradox drag is similar to the Lynx 14 drag. I have 2 x 85AH leisure batteries feeding a 24V PWM speed controller.

Initially a 20A 24V Bicycle speed controller, but that overheated after a few years probably because of its small case and limited surface area. I have upgraded to a 40A/50V speed controller with better heatsinks. Both were bargains on Ebay.

I had a bog standard freshwater motor for a few years, eventually the brushes gave out and after opening it was full of oily water and the bearings were knackered. But it was cheap enough to replace with a Minn Kota freshwater motor. Al reckons the briny versions are identical but use stainless bolts! Originally 30lbs now 32lbs thrust. It might be worth opening them every year or so, to drain out water and re-grease the bearings.

Jeremy thought the 24V system hit the sweet spot, reduced current and less discharge compared to one battery. In turn that would give a better range per battery, and it did.

Most trolling motors use resistors in speeds 1 to 4, only 5 is a direct motor connection. So the PWM controllers are essential and increase range considerably (up to 3 times possibly).

I charge 3 times down the Thames: Shifford Lock, Abingdon Lock and the campsite at WallingFord.
You need a Y splitter as the Abingdon Lock island only has one 240V outlet; having said that it was no problem to organise a shift system 2 years ago with a canal boat owner.

The cheaper MPPT controllers are a rip-off and consume a lot of standby current. Ideally you want a stupid Steca controller with a 3 colour led; it also has one of lowest standby currents. Last year I had a fancy digital voltage readout controller and left it connected to one panel and one battery.

Over the winter the panel voltage died and the standby current slowly took the battery down to 6.2V !! . My fault, I now have a dead battery; but it was the first battery I bought. Never let them drop below 12.6V

If fact, we should design our own controller. Minimal standby current, fixed float voltage is enough. Two diodes and a 15V regulator will give about 13.6V, almost zero discharge current but 10% is wasted when charging - you get the idea.

For monitoring the batteries an LCD voltmeter module and simple push button would be my choice.

Down the Thames a diode would be sufficient, as the PV voltage/current is unlikely to be too much for the battery.

-Paul

[Alan]

A second hand Minn Kota? There is one on ebay right now which looks good, 28lbs thrust.

I had a Minn Kota 32 on a short fat heavy grp dinghy a few years back and I remember that it drew 190W at full power. Your Paradox being longer, heavier but thinner (maybe) might take a bit more say 240W or 20A from a 12v battery. You might be able to travel for 4 hours on a 110Ah leisure battery (27kg) taking 80Ah from it. So if you can work out how many Wh you can get from a particular solar array you can take the 240W as a ballpark figure to guess how many hours of "free" travel you could get in a day.

The motor on ebay has a membrane switch control which makes me think it has a pulse width modulated speed control, not resistors, so nothing to be improved there but some people have fitted a model aeroplane propeller and a fairing around the horrible round vertical shaft to increase efficiency.

[Paul H (admin)]

On the subject of power consumption, near Lechlade I could push MilliBee along as low as 50 Watts but that only gave a slow speed, so slow I dropped to the back of the pack. But it's not a race!

I measured that with a common RC volt/amp/power meter. Maximum power was about 325 Watts with the bicycle controller, but I keep away from the higher powers to keep the batteries healthy.

-Paul

[alopenboat]

On 20 Feb 2018 at 10:30, Randonneur [via UK HBBR Forum] wrote:

>
>
> This is a trolling post  
>

I have a Minn Kota 28lb thrust with a single 80AH AGM battery. I
measured it at approximately 3 knots, consuming 30 amps at speed 5
and 2 knots, consuming 15 amps, at speed 4.

I have a 20 watt solar panel which keeps the battery fully charged
while running/charging echo sounder, gps, vhf, laptop, phone and
lights but needs a couple of days to charge up after running the
motor for an hour or so.

Where I expect to use the motor for any distance I carry an on-board
petrol generator. I have only done this a couple of times as it is a
pain.

I can't really recommend it for driving the boat for any distance
though I found it very useful for getting up the river Frome to Ridge
Wharf against the current (Poole Harbour).

As for the Thames Raid, I sculled most of the way (but as it is with
the current that is not so hard) using the motor only where it was
raining or against a nasty head wind. With a couple of spare
batteries it would probably be possible to motor the whole way as
there are now several charging points along the way.

--
Sail when you can, row when you must, motor only
when you have to be at work in the morning.

Alastair Law
Yeovil, England.
<http://www.little.jim.freeuk.com>

[Randonneur]

OK.

Thanks for your thoughts on the matter.
I think something with a bit more thrust would be more appropriate, (something around 40lb).
I'll probably go for one of the cheaper clones, like the Bison (about £100 for a 40# one) and 100 or more Ah batteries.
I'll be sculling, paddling or sailing the majority of the time, so the motor is just there for when I need to make a brew whilst on the move.
I'll add an ESC  and look at adding about 50W of solar to keep me in touch with civilisation between shore power hook ups?

[alopenboat]

On 28 Feb 2018 at 4:48, Randonneur [via UK HBBR Forum] wrote:

>
>
> OK.
> Thanks for your thoughts on the matter.
> I think something with a bit more thrust would be more appropriate,
> (something around 40lb). I'll probably go for one of the cheaper
> clones, like the Bison (about £100 for a 40# one) and 100 or more Ah
> batteries. I'll be sculling, paddling or sailing the majority of the
> time, so the motor is just there for when I need to make a brew whilst
> on the move. I'll add an ESC  and look at adding about 50W of solar to
> keep me in touch with civilisation between shore power hook ups?
>

Be sure to let us know what speed vs current you get with a 40lb
thrust.

Are you intending to store it below when not in use? That's what I
do. I made a neat stowage on the stbd side of the forward stateroom.
Then found the motor was about 3 inches from my compass.

--
Sail when you can, row when you must, motor only
when you have to be at work in the morning.

Alastair Law
Yeovil, England.
<http://www.little.jim.freeuk.com>

[Paul H (admin)]

That sounds fine Pete. 50Wp of solar will charge most things.

The key decision is 12V or Jeremy's and my recommendation of 24V.

The latter needs 2 PV panels and somewhere to mount them. I'm assuming you will solar charge the traction batteries and charge gadgets from them.
Or you could have a small 12V battery for gadgets and 2 traction batteries for 24V.

I never tried one 12V battery with an ESC, but it would deliver twice the current with a greater DOD.

You could see how it goes, but on my first Thames Raid I quickly realised 85Ah was not enough for MilliBee.

Cheers
Paul

[alopenboat]

On 28 Feb 2018 at 7:41, Paul (admin) [via UK HBBR Forum] wrote:

> > You could see how it goes, but on my first Thames Raid I quickly
> realised 85Ah was not enough for MilliBee.

I, on the other hand, managed quite well with 80Ah. That was sculling
where convenient and using the motor mostly where it was raining or
there was a significant head wind. I had no solar panel but found
that there were sufficient charging points at the overnight stops.

--
Sail when you can, row when you must, motor only
when you have to be at work in the morning.

Alastair Law
Yeovil, England.
<http://www.little.jim.freeuk.com>

[Randonneur]

On Wed, Feb 28, 2018 at 2:41 PM, Paul (admin) [via UK HBBR Forum] <[hidden email]> wrote:

That sounds fine Pete. 50Wp of solar will charge most things.

The key decision is 12V or Jeremy's and my recommendation of 24V.

The latter needs 2 PV panels and somewhere to mount them. I'm assuming you will solar charge the traction batteries and charge gadgets from them.
Or you could have a small 12V battery for gadgets and 2 traction batteries for 24V.

I'm working on the details. I'm assuming your Minn Kota is nominally rated at 12v, but you run with PWM at 24v?

I will be normally mostly yulohing, so I'd hope to keep the motoring to the bare minimum. 

But I need to be as independent from shore power as possible, and I tend to run a lot of gadgets too :-) 

this is my blueprint, but I may half the capacity and see how I get on!

https://daveskaife.wordpress.com/2014/11/03/my-electrical-system/

[Randonneur]

Meanwhile, in sunny Florida, this is currently taking part in the Everglades Challenge.

One up on Paul?

Or if that's not your thing, some more raid boats here.
https://www.facebook.com/travis.haggard.54/posts/1685651184789787

[alopenboat]

On 3 Mar 2018 at 9:29, Randonneur [via UK HBBR Forum] wrote:

> I will be normally mostly yulohing, so I'd hope to keep the motoring
> to the bare minimum. But I need to be as independent from shore power
> as possible, and I tend to run a lot of gadgets too :-)
>

Whenever I am on the move I run, directly from the boat battery, an
echo sounder, Navionics on a phone and a h/h gps. I also
intermittently charge my vhf and laptop and run nav lights and
ballast pump. I find my 20W solar panel more than keeps up with it
all.

On the other hand, an hour of motoring takes a couple of days to
replace.

--
Sail when you can, row when you must, motor only
when you have to be at work in the morning.

Alastair Law
Yeovil, England.
<http://www.little.jim.freeuk.com>

[Paul H (admin)]

Pete

Yes the motor is 12V but the PWM is 24V to be battery friendly.
The bike controller was current limited to 20A @ 24V  so that ensured the motor was not overdriven.

That blueprint is almost identical to what I installed. Shop around for circuit breakers instead of fuses.
Add a switch or push button for the voltmeter to avoid the steady drain - the solar controllers tend to have a high quiescent current also.

The cheap controllers can be unreliable. Pick the simplest or splash the pension lump sum on a Steca controller.
For example:
https://m.ebay.co.uk/itm/STECA-SOLSUM-10-10C-10A-12-24v-Solar-Charge-Controller/322569414308

Paul