rye

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hi
i just finished this boat http://www.rcuniverse.com/forum/m_6109290/tm.htm
it has a 12 volt 7amp gel cell battery that is 5,25 lb ,i would like to get a battery that weight is a lot lighter with some more power right now it gets about 15 minutes i have 2 900 viper motors and a sc480 esc thanks ps how long do i charge the 7amp 12 volt gel-cells for the charge is http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXL3
thanks rye

mrasmm

probably go with 3s lipo's that are 7Ah or something, so it is really close to the simular rating, all depending on how many amps the motors draw, and how much run time you need. I dunno that much about saftey issues with lipo's on the water, or if there are any special considerations that way. You could also go with NiCD's or NiMH's, but I dunno how much weight savings you would have.

Also a lipo will need a lipo charger, and you will have to read up on the saftey info, and they can be kinda pricey. Also I dunno how many amps those motors can draw cont, so I can't really tell you how many C's you need, but hopefully they shouldn't be drawing over 70A between the two.

Lipo's are gona be pricey at that 6Ah 3s lipo is gona run you atleast 170 bucks
http://www.commonsenserc.com/product...roducts_id=208

that might not be what you are looking for. Anyways it would be helpful if you would reply back how many amps can the motors use cont, how much surge, what is your ESC rated at, and how much run time do you want.

rye

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here what i got i dont know much on this http://206.206.85.209/xtdoc/Details....w&store=mhzusa
esc 240amp surge thanks rye

rye

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found the esc spec-http://www.modelcontrol.com/sc480.htm

Tim@MRC

You could always go with 4 - 7.2 volt 4200 mah NiMH batteries and run 2 in series and 2 in parallel. This would give you 14.4 volts( a little more speed) and 8400 mah ( a little more run time). Or even 4 - 8.4 volt and run 2 in series and 2 in parallel. With a 977 you can charge 2 batteries at a time at 5 amps so this would cut down on your charge time.

Tim

rye

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thanks tim
how much weight is that and what size would all that be and if i go that route where do i get them and could i get a drawing on how to wire all this ,i am a real dum-dum when it comes to this thanks rye

Tim@MRC

Each battery weighs about 1 pound, give or take. Here is a quick and dirty diagram. I would definitely use a Dean’s plug or equivalent. Actually, below are links to ones already made up, you would need 2 parallel adapters and 1 series adapter.

[link]http://www.bphobbies.com/view.asp?id=A0320181&pid=B1858542[/link]

[link]http://www.bphobbies.com/view.asp?id=A0320181&pid=B1858541[/link]

rye

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hey thanks does it matter who make the 4200 or where can i get them and could i use this to charge them thanks
http://www2.towerhobbies.com/cgi-bin...?&I=LXXG87&P=7

Tim@MRC

As with most things, you get what you pay for. So while I wouldn't necessarily get the most expensive pack, I wouldn't get the cheapest either. Also, using 4200 mah was only a suggestion. You can certainly use 3600 - 3700 mah and still be ahead of the 7 Ah gel cell. I would expect that you would pay around $45 - $60 per battery for the 4200, and around $40 - $45 for 3600 - 3700 mah. I've seen batteries offered with the Deans connector already on them, so you might want to look into that.
As far as the charger goes, I really don't like "Pulse" chargers. Batteries tend to get a little hotter while charging, and I've heard an audible buzzing sound coming from batteries being charged on a Pulse charger. Now this is just me, but I don't think batteries should buzz while being charged.

Tim@MRC

One more thing, this is a forum for MRC chargers. So of course I'll recommend that you use the one of the fine MRC chargers that we offer. The 977 would do just fine, as it has 2 outputs that can charge at 5 amps per side, it has a 4 amp discharge on channel A, and it comes with a 10 amp power supply.

[link]http://www.modelrectifier.com/search/product-view.asp?ID=1908[/link]

rye

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thanks tim
ill be intouch soon rye

Tim@MRC

No problem...anytime.

Tim