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Wow the SV27 nitro kills my SV27 Brushless, why?

Old 08-04-2007, 08:27 PM
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m3cosmos
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Default Wow the SV27 nitro kills my SV27 Brushless, why?

We were testing both boat and this forum really had me believing that the electric is faster. But i guess the nitro version pass the electric version easily. Probably 7mph.

I actually got a great deal for my SV 27 nitro (missing engine no prop) so i purchased a grim racer 40X53 prop with the .18 CVR os engine. I do not know how the .18 os compares with the stock aquacraft but the nitro makes the electric look silly. After break with 15% in i'm going to run 35% fuel and hope to get a little more speed out of the nitro. I'm going to try 7 cells on the sv27 brushless and bring my GPS or radar gun to settle things straight

Would 7 cells close the gap with the SV27 brushless. I do not have 4200 batteries and stuck with the old fashion 3000 ish.

Old 08-04-2007, 11:14 PM
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Ron Olson
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Default RE: Wow the SV27 nitro kills my SV27 Brushless, why?

Try 14 cells and tell us how it went. I ran my Nitro version against FE Chris' BL Super-Vee 27 and we were very closely matched. I was only on my 3rd or 4th tank of fuel with a slightly fat needle.
Old 08-04-2007, 11:35 PM
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Dan S
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Default RE: Wow the SV27 nitro kills my SV27 Brushless, why?

you said the magic word,

the SV27 brushless is faster than the nitro version when equipped with the stock Aqub 18 and the stock prop.

Dan.

The CVR and the 40x53 prop made the difference.

Dan
Old 08-05-2007, 09:56 AM
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m3cosmos
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Default RE: Wow the SV27 nitro kills my SV27 Brushless, why?

I'm thinking about some IB4200 14 cells. Would that fry my stock ESC/motor? This hopefully the boats would be evenly matched.
Old 08-05-2007, 10:01 AM
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Default RE: Wow the SV27 nitro kills my SV27 Brushless, why?

I don't know as I've seen some talking about using 4800 cells.
Go over to the electric forum and see what they're up to.
Old 08-05-2007, 12:42 PM
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saleens7
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Default RE: Wow the SV27 nitro kills my SV27 Brushless, why?

it should take 14 cells...many have used 14 cells before with it (some did use IB4200's as well).... the batts wont kill the motor/esc....its the amps the motor draws....if the motor draws more amps than the esc can handle, it might fry it....if it would also pull more amps than the batts can take, the batts might get very warm (even hot) and it could cause some damage to the cells...one thing though, youll have to disable the BEC to run 14 cells...

another thing with IB4200 cells is that they self-discharge very rapidly (compared to other cells)...if you let them site for 2 weeks they could loose alot of capacity and if they drop below a certian voltage they might not be able to hold full capacity anymore...all cells self-discharge, its just the IB4200 does it faster than most others...although if you charge the cells every few days you dont use them, you should be fine...(its also best to charge them at 1C or below (IB4200's 1C rating is 4.2amps)...its also good for the first charge that you charge the cells at a low amp rating....like below 1 amp...(i remember being told .1 amps before)....although you can get away with chaging them at a higher amperage than that, it could help the cells last longer....
Old 08-05-2007, 02:50 PM
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m3cosmos
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Default RE: Wow the SV27 nitro kills my SV27 Brushless, why?

Wow, i didn't know all of that and thank. Self discharge really sucks. Perhaps GP3900 would be a better pic for my case. I like the BEC so perhaps running cheapo 8.4 NIMH would be ok?
Old 08-05-2007, 05:39 PM
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Default RE: Wow the SV27 nitro kills my SV27 Brushless, why?

you cant use BEC if you use more than 12 cells....you could use the cheapest cells you can find, but if you used 14 of them, you cant use BEC....the mah of the cell is what gives you run time and the amp draw of the cell....the more mah you have, the more run time you will get...as well as the more amp draw from the motor it can take...i beleive the IB4200's C rating is 10C....which means 42amps....so if your motor draws 42amps or less, you cells should take it....although people have been using these IB4200's in applications that pull way more amps than that.....although this will decrease cell life and if the amp draw is too much it could possibly damage the cell...another thing, never dump the cells (use them until the boat cant move anymore.)....if you dump them it could decrease the capacity of the cell.....once you start to see the boat slow down, pull it in...

i would just stick with 12 cells for now...that way you can still use BEC....youll still get speeds in the low to mid 30's on 12 cells....

another thing, if you buy new cells, when you first run them, the boat may seem a little slow....it usually takes a few charges and discharges of the cells before they run at their full potential....

you may not like self-discharge, but ive heard all cell do it, its just some do it faster than others....you could use the IB3600....its a very good cell...durable, reliable, and they have a much longer shelf-life (time it takes for the cell to completely self discharge)......

here are some other packs to look at (they will need deans connectors to work with the supervee esc)

http://www2.towerhobbies.com/cgi-bin...?&I=LXMND3&P=0

http://www2.towerhobbies.com/cgi-bin...?&I=LXNCR2&P=0

http://www2.towerhobbies.com/cgi-bin...?&I=LXLFW4&P=0

http://www2.towerhobbies.com/cgi-bin...?&I=LXLFW5&P=0 (7 cell pack)

if the packs dont have deans connecotors, but instead tamiya;s, you can use this adaptor

http://www.offshoreelectrics.com/pro...od=dh-gpmm3130 (if you do need them, buy two...one for each batt pack)

there is alot to learn about electric....i havent even learned half of what some know....
Old 08-05-2007, 06:00 PM
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m3cosmos
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Default RE: Wow the SV27 nitro kills my SV27 Brushless, why?

I'm not new to electrics but just do not know much about the new IB4200's. I did not notice that much self discharge with GP3300 cells and anything similar would be acceptable.

I have one of these 7.4V lipos for my brushless on road car.

[link]http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXLXR6&P=ML[/link]

If i get another one perhaps, the handling would be better and able to use BEC? The voltage is a tad higher at 7.4 but has anyone tried these on the SV27? I'm not so worried about purchase cost but if it dunks in water I really do not want to kill $280 worth of batteries.
Old 08-05-2007, 08:51 PM
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Default RE: Wow the SV27 nitro kills my SV27 Brushless, why?

i think BEC only works up to 3s lipo....so youll probably have to disable BEC, but even with the added weight of a receiver pack, it still might be lighter since the lipo is lighter than nimh

ive heard good things about GP cells as well....

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