battery drain

[aki 0]

hi guys my 74 ah battery goes flat after about 4 days is this normal? ive checked the drain with a multimeter and its 0.07amp with 0.05amp caused by my alpine head unit!! does this sound normal or is my head unit causing the problem (ie is it faulty?) i dont know where the other 0.02 amp is going but my best guess is the alarm, ive pulled all the fuses and the only drain is the radio circuit! surely it doesnt need much current to store my presets and the time?!any ideas?

many thanks andy

[junkie 0]

Depends if its a Gel battery or not and could also be a sign the battery is starting to fail, or a bad earth if you have recently been behind the headunit etc.

[dr_mat 0]

70 mA will drain a *fully charged* 74Ah battery in 44 (forty four) days..

 

So either your battery is nowhere near fully charged (voltage at the battery terminals would be 12.6V if it's fully charged), or you have far more drain than 0.07 Amps... (Or your battery is fooked!)

 

OR you're misreading your multimeter! 0.7 amp drain (700mA) will drain the same battery from fully charged in four days... ;)

[junkie 0]

Off topic but what does the 74ah and 55ah etc mean on the battery and how does it affect the car, start up or running etc?

[dr_mat 0]

"AH" = "Amp Hour". Which means the battery will deliver the EQUIVALENT of 74 AMPS for one HOUR before going flat. (or 37 Amps for two hours, or 18.5 amp for four hours .. or .. you get it .. )

 

What difference does it make? Pretty much none whatsoever, normally. But when the battery starts to get drained, the larger capacity battery will sustain it for longer before going flat.

[soother 0]

I have the same thing going on for the past 3 years iv never worked it out. :sad:

[borarob 0]

i have this issue - getting round it now by using a maplin solar trickle charger - on offer at the mo for 9.99!

[aki 0]

hi

you were right it was me missreading my multimeter ive got a constant drain of 0.8/9 amp and i was right it is my headunit! the problem was whoever fitted it used the constant live for both the stereo and the stereo memory if that makes sense!? ive removed the headunit and frankly its a shambles with a nightmareish collection of bullet connectors so im now going to wire it up propery to the ign live which dies when the key is removed and only wire the memory to the constant live! so basically my headunit was live all the time even though the face was off! mindyou the ign live cable is smaller than the constant live also anybody know where the ign live is fused? going to put an inline one in anyway just wondered tahts all im hoping that its going to cure my battery drain

many thanks for the help

sorry for the delay......im a bit slack!!

andy

[dr_mat 0]

Even if it's still live but turned off it shouldn't be pulling nearly an amp of current! Not a healthy setup..