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battery and charger choice

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howie55:
hi every one
I feel I am sitting in a minefield of information I am receiving from friends and companies all given in good faith, but of which I am confused and could do with help, the system I will be putting into my yacht which is 58" long with a beam of 15" and keel carrying 8lbs of lead, is a Spectrum DX5 transmitter, Receiver Spectrum 500, motor is a M500, ESC is Viper 15, Servo Winch is Hiteck HS785 HB, Battery 7.4V Li-Lon 1500mA, I am unable to find a charger with a bayonet end fitting with a female connection to place in the boat to allow me to charge the battery in situ
advice I have been given is the battery may not be big enough also, I should be looking at lead acid again I have no knowledge of what battery and which charger will be compatable together.
I have included two photos of my yacht, scratch built to my own plans and loftings,
looking forward to any advice you may give me 

Stavros!:
component shop will be able to supply a charging lead BUT BUT BUT it is not good practise at all to charge any batt inside a modle boat especially a lipo due to the fact you can not monitor the condition of it a lipo should really be charged without it being in a sealed metal container or alternativly in a lipo safe bag




Stav

dodgy geezer:
All batteries provide electricity, and all chargers provide electricl output, so it can sometimes be a bit hard to decide which is the most appropriate...
 
There are a few figures which describe batteries which might help you compare things:


Voltage - the 'pressure' at which batteries provide electricty. Your radio needs around 5v (provided by the BEC), your motor needs 6-12v. A 7.4V battery is fine.
Capacity - the amount of power in a battery, measured in amp-hours. 1.5 (your 1500 ma) is ok for a small radio. I would like more for your sail winch, and you defintely need more for your motor if you want to run it for any length of time. I might suggest 4 Amp-hours (4000ma) at a minimum, but a lot depends on how often you want to use it. If your motor draws, say, 3a, then you would have less than 30 mins run time on the motor alone with no radio. Might be ok if you use the motor very infrequently, but I would like a larger safety margin.
Discharge Rate - how much power the battery can put out at one instant - measure in Amps. This is often not well understood, since batteries are often designed fo two quite dissimilar functions: putting out a lot of power rapidly, or putting out a little power for a long time. You can pick a battery with high voltage and a lot of power, but if it puts it out very slowly it may not run a high-drain unit like a motor very well.  You probably need something that can put out a minimum of around 15A (start-up current) to run an M500 effectively. Which your 1500ma Li-ion should do...


Lead Acid batteries typically have good capacity, good voltage and a fair discharge rate. They are heavy and bulky, but that may not be an issue for a big yacht.
Ni-MH or Li-Ion are a good choice for your application - Li a bit more expensive than Ni.
Li-Po batteries are typically optimised for light weight and high discharge - they can also be a bit temperamental to charge. Your application does not need this.


I would consider your requirement in the light of the above info, then phone up Component Shop and ask for their recommendation.


A multi-purpose charger like the iMax B6 (and its clones) will usually offer multiple connector options. I would re-iterate Stavros!'s advice to take the battery out for charging - It's a good idea to disconnect all batteries if they are not being used to avoid the dreaded 'Black Wire' disease, and they should be regularly inspected all over for signs of damage, corrosion, etc...
 

chas:
You say you're getting confused, I'm not surprised, too much conflicting information can do that so I'll try and cut through all that.
1) listen to what Stavros is saying, dont try and charge the battery in the model, do it properly and safely.
2) You've been told the battery is too small, it probably is, the sail winch alone will use an appreciable amount of power leaving very little for the motor.
3 i wouldn't consider a lead acid, they're bulky and heavy, this will change the trim of the model and will lose power quickly under the load you are going to use.
4) contact component shop, ask about a 6 cell (7.2 volt) ni mh battery and multi charger as recomended by D G

ChrisF:
Overlander Batteries do some good smart chargers as well. You need one that will charge different battery types and carry out different functions not only charging e.g. balance charging, storage charging etc.

As has been said the capacity of the battery is too low for this use.

Chris

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