MilliBee electrics - for 2012 Raid

classic Classic list List threaded Threaded
27 messages Options
12
Paul (admin) Paul (admin)
Reply | Threaded
Open this post in threaded view
|

MilliBee electrics - for 2012 Raid

This post was updated on .
One for Jeremy - will this controller be ok with my electric outboard? (with resistive controls)

http://www.virtualvillage.co.uk/12v-30a-pwm-dc-motor-speed-control-regulate-rc-model-003601-054.html

I'm not sure if it will have current limiting but 30A is enough as the lowest speed takes about 8A.

The easy approach is to leave the outboard alone and run it at the full throttle settings and use the controller to vary the speed.

http://uk-hbbr-forum.967333.n3.nabble.com/Compact-DIY-generator-Honda-tp3596138p3602445.html

-Paul
Jeremy Jeremy
Reply | Threaded
Open this post in threaded view
|

Re: Motor Speed Controller

It'd probably be OK, Paul, but some of the ebike ones are around the same price and I know they have current limiting, so may be a better bet.  They also work at a higher voltage though, so may need their low voltage cutoff circuit adjusted to work down at 12 V.  Then again, you can always choose to run at a higher voltage with a throttle stop, as the controller will make a very efficient buck converter.  The advantage of this is the the current in the feed from the batteries to the controller is much lower, meaning lower losses in the wiring and better battery life from the reduced discharge current.  The latter point can be pretty useful with lead acid batteries, as they exhibit a pretty sharp decrease in usable capacity with discharge rate - lowering the current gives you  more usable Ah - because of Peukert effect.

This one: http://www.ebay.com/itm/NEW-36V-500W-Brushed-Speed-Controller-E-bike-Motor-Scooter-Supply-Kit-30A-/390350541633?pt=LH_DefaultDomain_0&hash=item5ae2b49341 is rated similarly to the one from Virtual Village, but is slightly cheaper and definitely has current limiting (although it may need to have the low voltage detect adjusted).

Ebikes use a voltage output throttle, so a pot can just be hooked up to the three throttle wires to give a speed control, or you can use a cheap ebike Hall twist grip throttle (http://www.ebay.com/itm/Black-electric-bicycle-scooter-bike-throttle-grip-china-mini-moped-/220867428897?pt=LH_DefaultDomain_100&vxp=mtr&hash=item336cb98221).

The current limit can be tweaked on these if need be, by trimming the value of the internal shunt resistor, so if you find you need more or less than the nominal 24 A then it's easy enough to adjust.
Paul (admin) Paul (admin)
Reply | Threaded
Open this post in threaded view
|

Re: Motor Speed Controller

Thanks Jeremy,
Is there an internal pot to adjust the undervoltage? I imagine the design is generic and parameters are tweaked for different voltages.

Sent from my HTC

Timmo Timmo
Reply | Threaded
Open this post in threaded view
|

Re: Motor Speed Controller

In reply to this post by Jeremy
There are days when I really wish I understood this!

Electrics make sense, electronics is another world.

Tim

On 22 Apr 2012, at 09:11, Jeremy [via UK HBBR Forum] wrote:

The latter point can be pretty useful with lead acid batteries, as they exhibit a pretty sharp decrease in usable capacity with discharge rate - lowering the current gives you  more usable Ah - because of Peukert effect.


Paul (admin) Paul (admin)
Reply | Threaded
Open this post in threaded view
|

Re: Motor Speed Controller

In reply to this post by Jeremy
Jeremy,
There is a 24V model with a 28A limit that is more suitable:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=130586585402&fromMakeTrack=true&ssPageName=VIP:watchlink:top:en#ht_4646wt_985

http://www.yi-yun.com/Product_Detail.asp?ID=96

I have 2 dissimilar batteries, an 85Ah leisure battery and a new, unused 65Ah car battery intended for my Mondeo before I scrapped it. I know the car battery won't deep cycle but apart from the Raid it will sit unused, so I might as well use it.


Timmo - we could explain the electronics after a few beers on the Raid.

-Paul
Port-Na-Storm Port-Na-Storm
Reply | Threaded
Open this post in threaded view
|

Re: Motor Speed Controller

In reply to this post by Timmo
And there are days I'm really glad I don't.
Jeremy Jeremy
Reply | Threaded
Open this post in threaded view
|

Re: Motor Speed Controller

In reply to this post by Paul (admin)
adminHBBR wrote
Thanks Jeremy,
Is there an internal pot to adjust the undervoltage? I imagine the design is generic and parameters are tweaked for different voltages.

Sent from my HTC
Usually there are a couple of fixed resistors in the voltage sense circuit (if the controller has one - not all do).  Adjustment is by swapping resistor values.
Jeremy Jeremy
Reply | Threaded
Open this post in threaded view
|

Re: Motor Speed Controller

In reply to this post by Paul (admin)
adminHBBR wrote
Jeremy,
There is a 24V model with a 28A limit that is more suitable:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=130586585402&fromMakeTrack=true&ssPageName=VIP:watchlink:top:en#ht_4646wt_985

http://www.yi-yun.com/Product_Detail.asp?ID=96

I have 2 dissimilar batteries, an 85Ah leisure battery and a new, unused 65Ah car battery intended for my Mondeo before I scrapped it. I know the car battery won't deep cycle but apart from the Raid it will sit unused, so I might as well use it.


Timmo - we could explain the electronics after a few beers on the Raid.

-Paul

The Yi Yun should be fine, it has a 20.5 V low voltage cut off, but this can be tweaked, I believe, by adjusting the value of an internal resistor.
Jeremy Jeremy
Reply | Threaded
Open this post in threaded view
|

Re: Motor Speed Controller

Just to add a comment about the batteries, Paul.  If you wired them in series for discharge (you can charge them in parallel) then my guess is that you may only be drawing around 6 - 10 A or so at 24 V when cruising (assuming you need around 150 to 250 W for cruise speed).  

A car battery, although not good for deep discharge, will probably deliver around 60 to 70% capacity, maybe more, at this low current draw, so my guess is you might get around 4 to 6 hours or more out of it.  If you disable the low voltage cut-off on the controller (but monitor the battery voltage) then when the car battery gets discharged you could switch the batteries to parallel configuration and use the remaining capacity in the leisure battery (albeit at a higher discharge current).

This might just give you around 6 to 8 hours run time, maybe more.  If you were to do some mods to your motor, as MCDenny did here: http://www.boatdesign.net/forums/boat-design/efficient-electric-boat-27996-17.html#post305142 then you could significantly increase your range, I believe.
Paul (admin) Paul (admin)
Reply | Threaded
Open this post in threaded view
|

Re: Motor Speed Controller

Jeremy,

Are all the e-bike controllers switched mode? (e.g. higher motor current than battery current). If so that 24V controller will be an interesting experiment. I'll be carrying Al's genny so at discreet moments well away from the HBBR pack it could charge the batteries en route - perhaps a 24V charger is worth getting, also my solar charger auto adjusts between 12/24V.

I'm not sure about fitting a wooden 10x6 prop like Denny because there are plenty of tree roots along the Thames waiting to smash it to pieces! I fitted a steel pin to my 2.5hp prop to stop endless breakages of shear pins - the nylon prop takes on the tree roots and wins every time.

In the next post I'll reveal my secret weapon, something that can generate 7A at 25V if I can fit it to MilliBee.

-Paul

Paul (admin) Paul (admin)
Reply | Threaded
Open this post in threaded view
|

How to mount a solar panel

Chaps,

I want to mount this 5ftx3ft solar panel on MilliBee's cabin for the Raid. All suggestions are welcome on mounting the panel:



Flush with the cabin rear it overhangs the cabin front an inch or two, with plenty of clearance to the gunnels. Aluminium angle brackets are the simple approach for a flat mounting which is conventional for solar boats.

However it would be clever if the panel could rotate towards port or starboard to catch the sun - I know we all love an engineering challenge.

Peak power is 25V at 7A directly facing full sun, that might move MilliBee at 1 or 2 knots but it will at least reduce the need for battery charging and it will be endless fun watching peoples reaction.

Illusion hit the TV in style...who knows...

cheers
-Paul
Paul (admin) Paul (admin)
Reply | Threaded
Open this post in threaded view
|

MilliBee electrics - for 2012 Raid

The Chinese bike controller is wired up to my electric outboard and working well. Two 12V batteries provide 24V into the controller which gives 12V to the outboard.

Technical details
------------------
Test measurements in dustbin full of water:

Battery Current  |  Motor DC/AC Current (Amps)
2.65                     11.5  /  1.2
3.5                       13.5              Motor voltage 6.7 Volts*
4                          14 / 1.52
6                          18 / 2
6.9                       19.4  / 2.05    Heavy wash - motor looked powerful

All measurements +/- 5% and I could not read above 20A. The controller seemed to compensate for water turbulence so motor current was not steady and difficult to read. AC current >0 indicates the PWM is not 100%. The controller case felt cool so its working close to 99% efficiency (as expected)

*87 Watts from battery, 90 Watts into motor so the measurements make sense within 5%


Non-technical summary
--------------------------
It worked!  Batteries last longer when discharged slower - so sharing the load on two batteries this way is more than "twice as good" as one battery.

Also the cheap outboards control speeds by switching resistors in series with the motor to slow it down. Those resistors get hot and waste valuable power. Jeremy thinks there will be 20% extra range with an efficient electronic controller - the worst case for my outboard is 33% wasted at the lowest speed.

On the 2009 Raid I just about limped into Shipham lock on one battery. With two batteries and efficient control progress should be better. Also with a charge overnight hopefully the 2nd day will be silent electric also.

-Paul
Timmo Timmo
Reply | Threaded
Open this post in threaded view
|

Re: MilliBee electrics - for 2012 Raid

I need to ask a dunce question.

Am looking forward to some basic electronics education while on the raid but for the moment:

I have a 12 Ah 12 volt battery

An iPhone battery is 1432 mAh which I think is the same as 1.432 Ah.

Does that mean I can charge the iPhone (from flat) just over 8 times from that battery using the charger lead I use in the car and no other electronics stuff?

Alternatively, if an iPad battery is 6930 mAh ( 6.39 Ah?) could I charge that once and the iPhone 3 times.

Or is it all a lot more complicated!

Comments and corrections welcome.

Tim.

On 13 May 2012, at 16:45, adminHBBR [via UK HBBR Forum] wrote:

> The Chinese bike controller is wired up to my electric outboard and working well. Two 12V batteries provide 24V into the controller which gives 12V to the outboard.
>

Paul (admin) Paul (admin)
Reply | Threaded
Open this post in threaded view
|

Re: MilliBee electrics - for 2012 Raid

Timmo,

Yes your calculations are right - take a pat on the back!

However running a battery flat can shorten its life - depending on the battery type it should be charged around 40%, some deep cycle batteries can go as low as 20%. Electronic devices typically have a cut-off voltage of 10.5V - if the battery drops that low the device cuts off to avoid further damage.

Fear not - wait for the next posting!

-Paul
Paul (admin) Paul (admin)
Reply | Threaded
Open this post in threaded view
|

Re: MilliBee electrics - for 2012 Raid

I seem to have created the Mother of all floating battery chargers:



Why do boats turn into junk magnets? She was tidy enough for the Queen a few days ago.

She doesn't look too bad from the side and the solar panel will clear lock walls by at least one foot:



Remember those chunky stainless hinges on Illusion's rudder? they are soon to be recycled to secure the panel at the front. The rear will lift up to clear the companionway and the idea was inspired by the raised cabins on Broads yachts.



Apart from charging all our IGadgets it should provide a significant contribution to the outboard - making the batteries last longer, extending the range.

-Paul



Alan Alan
Reply | Threaded
Open this post in threaded view
|

Re: MilliBee electrics - for 2012 Raid

This post was updated on .
I'm looking forward to hearing how you get on with solar. I'm guessing that you will not need any charge controller as the most you can deliver to your batteries is 12.5v/7A. As the batteries go above 12.5v while charging approaching 13.8v, the current will reduce considerably so overcharging will be impossible. Unless a certain person knows better.

If you want to spend more money and waste more time how about this: A Neodym wattmeter (cheapest Modelmaniacs £20) could be connected between your panel and battery permanently to display instantaneous watts, volt, amps and amp-hours total from your panel over the whole trip. This device also has a servo tester included and I have used one to control the ESC of my own 24v 750w outboard. It's not waterproof though and mine no longer has a display after being out in the rain.

alan
Jeremy Jeremy
Reply | Threaded
Open this post in threaded view
|

Re: MilliBee electrics - for 2012 Raid

The charge controller on my electric boat uses an MPPT to get a bit more charge from the panel under varying conditions and has a pair of power meters, one reading the solar panel voltage, current, power etc and the other reading the battery discharge voltage, current power etc.  Here's a picture of the unit resting on top of my lithium battery pack (which has it's own battery management system built on to the end, with an individual cell voltage display).

Randonneur Randonneur
Reply | Threaded
Open this post in threaded view
|

Re: MilliBee electrics - for 2012 Raid

In reply to this post by Paul (admin)


On Sun, May 13, 2012 at 10:13 PM, adminHBBR [via UK HBBR Forum] <[hidden email]> wrote:
I seem to have created the Mother of all floating battery chargers:

Well I love your optimism.
I just live in hope that the sun shows it's face a few times!




Paul (admin) Paul (admin)
Reply | Threaded
Open this post in threaded view
|

Re: MilliBee electrics - for 2012 Raid

In reply to this post by Alan
Alan,

There is a solar charge controller. It's a cheap Chinese model but having a float voltage does protect the batteries from overcharging between voyages, plus every 28 days it applies an equalisation charge, LEDs show the battery state and it can switch an anchor light on from dusk-dawn automatically - not bad for £12.

It's a 24V system into the motor speed controller and the solar controller auto switches between 12V and 24V. So it will charge at 24V and I've ordered a switched-mode 24V/12A mains charger which is just 195mm x 105mm x 5mm, ideal for permanent installation.

Good idea about a Neodym wattmeter - but I'm more interested in current/voltage from battery to motor controller.

Will the Neodym measure negative currents?  A current panel meter between battery and the 24V rail can show positive when charging and negative when running the motor e.g. it will show the net current out of the battery. I can switch off the motor for a few seconds to see the charge current etc.

So ideally it reads +/- current like a panel meter, but its a good package at £20 though, boxed and ready to go.

cheers
Paul

Edit: Making the whole system 24V means the solar panel or genny can charge both batteries at 24V as I motor along. So the batteries will stay in series always, the 12V supply for cabin lighting will be from one battery.
Jeremy Jeremy
Reply | Threaded
Open this post in threaded view
|

Re: MilliBee electrics - for 2012 Raid

AFAIK, none of the RC model type wattmeters measure negative current, which is why I opted for two of the cheap Turnigy ones (one on the charge feed and one on the battery discharge) in my box.  I fitted them inside a waterproof housing, with a new clear screen bonded over the displays.

The only wattmeter like this I know of that works both ways is the Cycle Analyst, from ebikes.ca.
12