ESC question

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26 June 2014 at 19:07 #49922
Karl Hemming
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@karlhemming34605
Hi guys,

I have just got myself a perkasa torpedo boat, she has a length of 93cm x 12cm beam. She's fitted with a MFA marlin 12v motor with a 50mm 2 bladed prop. I am going to use a 12v 7ah lead acid battery for power. This is the first time I've done a boat this big so I have no idea what esc to use.

Any help would be great!

Karl
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26 June 2014 at 19:07 #2403
Karl Hemming
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@karlhemming34605
26 June 2014 at 19:27 #49923
Dave Milbourn
Participant
@davemilbourn48782
Karl
1. Forget the lead-acid battery. It's far too heavy for a planing model. It will perform more like a canal narrow-boat than a fast patrol boat – although it will do so for hours and hours…………..You need a 10-cell pack of NiMH cells. **LINK**
2. Buy a Microgyros FR40 speed controller. **LINK**
3. That's it.

Dave M
26 June 2014 at 21:55 #49928
Karl Hemming
Participant
@karlhemming34605
Many thanks for that Dave,

I was wondering, could I run two 6v 3300mah 5 cells instead. Seems to work out almost 20 quid cheaper that way.

Being a cheap sod, every penny counts!

Karl
26 June 2014 at 23:25 #49929
Dave Milbourn
Participant
@davemilbourn48782
Yes, if you wire them in series, but you won't get run times as long as with the 5AH cells. "You pays your money" etc.

DM
27 June 2014 at 08:50 #49931
CookieOld
Participant
@cookieold
Hi Karl , I am also building a 1:24 scale Perkasa and was unsure what Motor & Battery to use . I got a lot of really good advise off people on this forum inc DM . The general opinion was to go with Brushless and Lipo,s . I was lucky enough to bump into a chap with a Perkasa at a local lake who is running with a brushless set up and it goes really well with good run time as well. The set up i will be using is 2 brushless motors / 2 brushless esc,s and 2 Lipo batterys this will cost around £ 160.00 all in . I know it,s quite a lot of money but i figured it,s best to do this rather than fit the 3 brushed motors i have already bought only to be dissapointed , I will find us for the brushed motors and esc,s on another project i hope. Please keep us informed on your choice.

Cookie
27 June 2014 at 11:52 #49935
Dave Milbourn
Participant
@davemilbourn48782
I have to point out that there are two different-sized Perkasa kits available; Cookie has the big one and Karl the smaller one. I'm pleased that Dave appears to have found a brushless solution for his four footer. The smaller one needs less HP and so a brushed motor setup, whilst not ideal, is more practical (unless you use a lead brick for a battery!!).

DM
2 July 2014 at 19:53 #50063
Karl Hemming
Participant
@karlhemming34605
Good Evening Gentlemen,

Ok in the end I got hold of a JP 50A Marine esc. I took your advice Dave and got a 3700mah nimh battery pack. Still have a bit more work on the superstructure as when I bought her she was in a bad way but alas we are getting there.

Many thanks for the advice guys

Karl
2 July 2014 at 20:44 #50064
Dave Milbourn
Participant
@davemilbourn48782
Shame about the ESC, though.
3 July 2014 at 07:55 #50065
CookieOld
Participant
@cookieold
Hi Dave , As i have said i am going to use the brushless set , But the brushed ESC,s i have already bought are the JP 50 amp that Karl as bought and i intended to use these on a future project so i am alarmed that you seem to have issues with these . What,s wrong with them in your opinion as i might be able to exchange them for a better one.

Cookie
3 July 2014 at 07:57 #50066
ashley needham
Participant
@ashleyneedham69188
cookie. i hope that the brushless solution you have choisen works out. As you have not run the brushed motors you will not have anything to compare it against.

out of interest, how did you arrive at the right Kv and power rating for the brushless motors?

Ashley
3 July 2014 at 08:47 #50069
CookieOld
Participant
@cookieold
Hi Ashley , I got a lot of good advise off people on this forum , all saying that brushless was the way to go then by chance when down at the pond there was a visitor with luck would have it a Big Perkie . He at first went with the brushed set up very similar to the one i was going to use he used a 12v SLA to power his center 850 motor and 2 12v Nimh 5ah sticks for his 2 outer motors , he told me he got good performance but only 10 mins good run time . So he went over to brushless the performance is great ( catches pidgeons ) and he gets a good 20 mins run time . He uses 2 brushless motors and 2 ESC,s and 2 LIPO batterys . He said he would email me the kit he used for me to copy . Once i get the info i will pass it on to you, sorry i cant give you a precise account of how he arrived at the right Kv and power rating . Your thread about having some sort of ref data regarding brushless set ups in different applications is a realy good idea it would take the guess work out of it .The guys set up worked really well but he said he did not know enough about brushless to say it was the best set up he just hit lucky with it. Anyway Ash as i said i will pass it on when i get it.
3 July 2014 at 08:51 #50070
Dave Milbourn
Participant
@davemilbourn48782
I've handled several of these ESCs. They most certainly won't take 50A continuous current; indeed 20A was about as much as they'd be happy with. They only run at 40% power in reverse. In the absence of an ACTion unit which will do the job at a reasonable price – plus the facility of BEC and LiPo battery support – I'd have gone for the Microgyros FR40 every time. It's a very nice little unit; will do 2v – 26v; has low battery alarm/cut-out; choice of four operating frequencies etc etc – I don't know how he makes them for the price. It's cheaper than the JP 50A and it's 100% British-made.

Mind you, once that lazy item Iain Lewis pulls his finger and his soldering iron out and produces the new ACTion P108 then all other bets are off.
3 July 2014 at 09:20 #50073
CookieOld
Participant
@cookieold
Thanks Dave , Have to say i have heard rave reveiws about the Microgyros FR40 since buying my JP , were can these be bought and a what price.
3 July 2014 at 10:10 #50074
Dave Milbourn
Participant
@davemilbourn48782
**LINK**

I think they're £25 but don't quote me. BTW it's best to phone Mike; he's not a great fan of E-mails.

Dave M
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