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Author Topic: MMM Portgarth build  (Read 150718 times)

T33cno

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Re: MMM Portgarth build......LiPo power questions
« Reply #800 on: October 31, 2017, 06:17:26 PM »

My first LiPo arrived  :-))  I will order three more as they will be ideal for the Shannon me thinks.


BIG BIG question of LiPo experts! How do you know how much you can discharge these batteries. What do you do and how do you know when to stop . Is telemetry involved and if so how fanks  :kiss:
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T33cno

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Re: MMM Portgarth build.....LiPo learning continued
« Reply #801 on: October 31, 2017, 07:53:34 PM »

Seems I can rig my ship with telemetry  :-))  Spectrum DX6 has telemetry which requires a module to report main battery voltage. A TM1100 looks favourite.
This is purely to avoid damaging the batteries by over discharge. However the battery does not state what the safe voltage level is.
Assuming the Spektrum defaults for LiPo cells are generic this will illuminate the answer to my question when set to 4S


Do I really need this or is it safe to just watch for a noticeable slow down? or is that already too late
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T33cno

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T33cno

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Re: MMM Portgarth build
« Reply #803 on: October 31, 2017, 09:18:13 PM »

Works great and easily fit four. Look at that  8) paxolin O0
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JimG

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Re: MMM Portgarth build
« Reply #804 on: October 31, 2017, 09:30:37 PM »

Normally the LiPo voltage protection is done by the esc. You need a LiPo compatable esc as this has the voltage detection built in and will stop power to the motor when it reaches the minimum.  If the esc is not set up for LiPos then you can buy a battery checker which plugs into the balance leads. You get one with Leds and a buzzer for the alarm to tell you to stop using the battery.
Jim
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T33cno

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Re: MMM Portgarth build
« Reply #805 on: October 31, 2017, 09:34:04 PM »

Thank you Jim but my ESC is an action electronics p94 mixer 6 to 24 volt rated that I donít intended to change
Iíve just ordered the telemetry enable receiver  :-))


Edit if your method cuts power to the motor then surely the boat will be adrift
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JimG

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Re: MMM Portgarth build
« Reply #806 on: November 01, 2017, 01:13:32 PM »


Edit if your method cuts power to the motor then surely the boat will be adrift

Under power the voltage from the battery will drop below its resting voltage. Once the cut off works  and the battery is left for a couple of minutes it will partially recover enough voltage for the esc to work again. The boat can then be brought back under low power.

Jim
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T33cno

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Re: MMM Portgarth build
« Reply #807 on: November 01, 2017, 01:53:02 PM »

Ahh thanks that makes sense  :-))
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T33cno

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Re: MMM Portgarth build
« Reply #808 on: November 01, 2017, 06:33:08 PM »

I found this extremely well written guide with all you want to/need to know about LiPos
This also covers Low voltage cut out on some ESC's as Jim has kindly informed above  :-))


Safe discharge voltage is 3volts per cell BTW
https://rogershobbycenter.com/lipoguide/
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T33cno

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Re: MMM Portgarth build......Spektrum telemetry
« Reply #809 on: November 02, 2017, 06:53:40 PM »

I'm happy now. This receiver arrived very quickly from Leeds Model Shop. I bought the last one in stock  :-)
Transmitter now set for telemetry and 4s LiPo so 17 volt max 12 volt min with 60 second reports at 12 volts or less.

Now bound and tested connected to a 7.4 pack which immediately voice alerts 7.4  :-))
Great piece of kit with a bind button to save messing with plugs and a remote extension receiver too .
This also monitors receiver voltage as it is and can measure RPM plus temperature with extra leads
Since buying two batteries I've found much cheaper from eBay hobbyking. at leat £8 less per battery delivered.

https://www.ebay.co.uk/itm/RC-Turnigy-5000mAh-4S1P-14-8v-20C-Hardcase-Pack/131573104355?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20160727114228%26meid%3Dd61b5b7557bd4163b41e129359132834%26pid%3D100290%26rk%3D2%26rkt%3D4%26mehot%3Dag%26sd%3D391314963395&_trksid=p2060778.c100290.m3507
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T33cno

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Re: MMM Portgarth build
« Reply #810 on: November 02, 2017, 07:28:27 PM »

Modify time is far too short.


So another bit of info......
2 of these 5000mah LiPo weigh 1020grams
1X 9AH pb weighs 2574grams
So using four Lipo reduces weight by 3 kg approx
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T33cno

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Re: MMM Portgarth build
« Reply #811 on: November 03, 2017, 11:27:15 AM »

WARNING!
This AR6600T receiver is not liked at all by my Action electronics. The P94 mixer was erratic and thinking it was faulty I fitted a new spare. The same problem persisted so I swapped back to my original receiver and all is now OK again.
Also for some reason the rudder channel does not activate/react to the stick to operate my bow thruster AE P93
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Paul2407

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Re: MMM Portgarth build
« Reply #813 on: November 03, 2017, 06:45:51 PM »

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T33cno

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Re: MMM Portgarth build
« Reply #814 on: November 03, 2017, 08:21:41 PM »

Cool  :-))  receiver won't be wasted I'm sure it will suit the Shannon although as yet I've no idea what ESC's I'll need  %%
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Paul2407

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Re: MMM Portgarth build
« Reply #815 on: November 03, 2017, 09:04:24 PM »

no I've no idea, I do like the idea of the Shannon, I had a 37ft sports cruiser years ago with twin Hamilton jet drives so know quite a lot about jet drives and to say I was very impressed with them was an understatement, but I had to sell to buy a house  :(( but really looking forward to your Shannon build
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T33cno

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Re: MMM Portgarth build..... my Samson post solution
« Reply #816 on: November 05, 2017, 03:45:39 PM »

I didn't want something that would have no strength or be repeatedly dislodged. The bulwark is not strong enough with the small point of contact. So......
I chose two brass tubes of a size that suited my eye that fit each other.
The thinner tube I fitted through the deck down to the hull. This is fixed with fusion adhesive.
I used set squares to ensure perpendicular.





The second tube I have cut to a height and bunged one end with beech dowel and sanded off. Drilled a 2mm hole for the brass peg. Used 2mm styrene for the securing plate that will not need to be glued to the gunnel. So it is demountable for painting or whatever else.













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Tafelspitz

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Re: MMM Portgarth build
« Reply #817 on: November 05, 2017, 08:42:24 PM »

Fantastic!  :-))
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T33cno

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Re: MMM Portgarth build
« Reply #818 on: November 05, 2017, 08:47:21 PM »

Thank you :-))
It's a very long road is it not  :o


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Tafelspitz

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Re: MMM Portgarth build
« Reply #819 on: November 06, 2017, 07:03:53 AM »

Yes, long indeed, and very winding in places  O0
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We live in a society exquisitely dependent on science and technology, in which hardly anyone knows anything about science and technology.  Carl Sagan

Paul2407

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Re: MMM Portgarth build
« Reply #820 on: November 06, 2017, 09:44:06 PM »


Worth taking your time Andy seeing the results so far and if the rest turns out anything of the same quality as the stuff you have already produced it's more than worthwhile waiting for  :-))


And just think you got to get some practice in before you start on that fabulous Shannon build  O0
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T33cno

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Re: MMM Portgarth build
« Reply #821 on: November 06, 2017, 09:50:42 PM »

Apparently the Shannon is designed to be as easy to build as an Airfix kit. That is straight from the horses mouth  {-)  Adrian
The Maltby will exercise all my acquired knowledge  :-))
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Paul2407

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Re: MMM Portgarth build
« Reply #822 on: November 06, 2017, 10:26:14 PM »

Ah The Maltby a boat I've read a lot about but yet to ever see one  :(( and unsure exactly what it looks like but I think it's looks a little like the Portgarth?
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T33cno

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Re: MMM Portgarth build
« Reply #823 on: November 06, 2017, 10:29:09 PM »

Ah The Maltby a boat I've read a lot about but yet to ever see one  :(( and unsure exactly what it looks like but I think it's looks a little like the Portgarth?


http://www.modelboatmayhem.co.uk/forum/index.php/topic,36015.0.html


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Paul2407

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Re: MMM Portgarth build
« Reply #824 on: November 06, 2017, 10:36:13 PM »

Yeah that is the one I was thinking of, but I think it's looks an easier build than the Portgarth (maybe wrong) just doesn't look as complicated but looks can be deceiving, whatever though I'm sure you will make a grand job of it
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