Model Boat Mayhem - Forum

Mess Deck: General Section => Chit-Chat => Topic started by: Andy H on November 29, 2010, 09:34:09 PM

Title: battaries
Post by: Andy H on November 29, 2010, 09:34:09 PM
Hi all,

This may appear simple to most. Can some explain the difference between the following;

a battary that is.............. 4.8V , 1200mAh........... & a battary that is........4.8V , 2100mAh
Title: Re: battaries
Post by: dougal99 on November 29, 2010, 09:45:47 PM
The mah value of a battery is the milli amp hour rating so a 1200 mah battery would supply 1200 ma for 1 hour or 600 ma for 2 hours or any combination. Consequently a 2100 mah battery will provide 2100ma for 1 hour etc. Basically the larger the mah value the longer a battery will last before a recharge is required. The motor/prop combination will take the amperage it requires, so the larger the battery mah value the longer it will last with a given combination.

HTH

Doug
Title: Re: battaries
Post by: Andy H on November 29, 2010, 09:49:21 PM
Hi doug.....thanks for your reply....so does the voltage drop during the time frame....andy
Title: Re: battaries
Post by: Andy H on November 29, 2010, 10:19:10 PM
As a by the way thing.........

I have a 6V 2000mAh battary powering my deck lights.....which are:

2 6V grain deck light bulbs.....1 port & 1 starboard 12V grain bulbs.....& 2 12V grain mast light bulbs

what should I expect from this in terms of brightness and length of time

Title: Re: battaries
Post by: BigA on November 30, 2010, 01:02:35 PM
Voltage will decrease with time - close to the end of a discharge cycle, NiMH packs show a drop that is more gradual than equivalent NiCd packs. The running time will depend on the current drawn by all of the components - motor, lights, etc. Without knowing these, it's difficult to estimate how long you'll get from a pack. The higher voltage (12V) lights are not likely to be as bright as the lower voltage (6V) ones, as they are only being supplied with 6V from the pack.

A.
Title: Re: battaries
Post by: malcolmfrary on November 30, 2010, 01:21:49 PM
The 6 volt lights will glow gently.  You might not be able to tell whether the 12 volt lights are working.
Think of the mAH figure as gallons of fuel.  The more gallon, the longer the run before refuelling, but equally, recharging (filling) at the same rate will take proportionally longer.
Title: Re: battaries
Post by: Colin Bishop on November 30, 2010, 02:06:17 PM
I find that 12v grain of wheat bulbs on 6 volts look quite accurate. Ship navigation lights are in practice quite dim compared with the other lights on board.

Colin