[DML] Re: How to figure battery life
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[DML] Re: How to figure battery life

Well first you need to know - what capacity has your battery ?
(that's the number before the "Ah" - called Ampere-hours)

then you need to know how much current you are sucking out of the 
battery. Just from the number of LED's alone you still don't
know how much they draw - You can drive a LED with 1, 10 or 
even 1000mA. Then it's the question - are they in series
or in parallel ? -> easiest way is to measure the current
you draw from the battery.

Then there's another not so simple question: how much charge
does the battery need to still be able to crank the car ?
10% 20% ? 30% ? (we leave the temperature problem out here
as it would make it even much more complicated).

you have a 50Ah battery fully charged (we assume it has no
tolerances...which is impossible...)

You draw continuously 1A

We assume you need 20% charge to still be able to start the car
50Ah * 20% = 10Ah -> you have 40Ah left for the LEDs.

40Ah / 1A = 40h - > 40 hours.

Headlights on: 2*55W / 12V = ~10A
40Ah / 10A = 4 hours and you have to push the car (or even 
less as I was only calculating the H4 low beams without the rest)

just the doors open with bulbs -> 5W/ bulb = 30W/12V = ~3A
40Ah / 3A = ~13h 

Doors with LED's that draw 20mA each -> 6*20mA = 120mA
40Ah / 120mA = ~300h

Hope this helps to calculate your own figures.

Elvis & 6548

> I'm trying to figure out how long a fully charged battery will 
> What is the mathmatical formula for doing it? All my lights (except 
> headlights) are LEDs. The tail & front market lights have 45 
> the side markers have 3 diodes, license plates have 6 diodes, door 
> markers (assuming I keep the doors open) have 6 diodes.
> So with doors open and parking lights on (headlights off) how long 
> my batter last from a full charge?

To address comments privately to the moderating team, please address:

For more info on the list, tech articles, cars for sale see www.dmcnews.com

To search the archives or view files, log in at http://groups.yahoo.com/group/dmcnews 
Yahoo! Groups Links

<*> To visit your group on the web, go to:

<*> Your email settings:
    Individual Email | Traditional

<*> To change settings online go to:
    (Yahoo! ID required)

<*> To change settings via email:

<*> To unsubscribe from this group, send an email to:

<*> Your use of Yahoo! Groups is subject to:

Home Back to the Home of PROJECT VIXEN

Copyright 2006 ProjectVixen.com.  All rights reserved.

Opinions expressed in posts reflect the views of their respective authors.
DMCForum Mailing List Archive  DMCNews Mailing List Archive  DMC-UK Mailing List Archive