Model Boat Mayhem
Technical, Techniques, Hints, and Tips => Batteries & Chargers => Topic started by: Brian60 on February 23, 2014, 01:58:51 pm
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Hey that rhymes :} Anyway I have no experience of using these things so if anyone can help....
I have a lipo battery that I bought on a whim, its marked 25c lipo 7.4v 1200mAh (2s1p) 8.88Wh
I know its 7.4v :-)) what does the rest mean?
I also want to use it in my sailing smack- but only if its going to have enough power- it will be powering two servo's and the receiver, one normal servo for the rudder and one sail winch for the sails. Is it going to be powerful enough for that? Bearing in mind 30 minutes sailing would be the max I would want anyway.
It has 5 wires attached, two (red/black) heavy duty cable, I aasume these go to whatever its powering? then 3 fine wires 2 black 1 red, what are these for?
Can I just hook it up to my standard charger via the heavy duty red/black cables?
Should I just consign it to the parts bin and stick with a 6v gel cell? this will be a permanent fixture, ie once it is in, there will be no getting it out,it will be sealed under the deck and part of the ballast way up in the bow.
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Hi,
The answer lies in your last paragraph - its not suitable for this intended use, as you need to remove it from the boat to charge.
Why? Well, the red/black cable are the connectors to load, and also the re charging connectors. The 3 fine wires are for balance charging, these connect to a dedicated lipo charger - no, you cant use your standard charger, they need a specific lipo charger.
And, they should be charged under observation for safety, they have been known to fail VERY spectacularly - look on u tube!
For info, the rest of your questions:
25c = discharge max current is 25 x capacity, in this case 1200ma (1.2a)
2s1p = 2 cells wired to give 7.4 v. Each cell gives 3.7 v under load (hence 7.4v) and have to be charged so that they are equal (balanced) voltage otherwise there could be a risk of a higher charged cell discharging into the lower cell which can be fatal for the battery.
My opinion? For this application, stick with the gell cell.
Ian
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7.4v is a tad high for a receiver.
Another reason to go gel cell.
If at all possible make the battery remove able.
If a cell goes down the battery will have to be replaced.
Ned
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Right then weigh the gell cell or simply make it a permament fixture in hte yacht....what you need is one of these
http://www.componentshop.co.uk/6-0v-aa-2600mah-hump-battery-pack.html (http://www.componentshop.co.uk/6-0v-aa-2600mah-hump-battery-pack.html)
I used to sail a marellhead for over 8 hours with one with NO problem at all..........Yes you will need to make a compartement for it ...FAR better than a Gell cell
Dave
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That is exactly what I use in my Marblehead
and my Victoria and after three years they
are still as good as new.
Ned
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Thanks for the info guys, i'll consign it to waste {-) I'll stick to the gell cell that I have, its a small unit from Maplin and doesn't weigh that much more than 5 AA's.