Head Unit to Leisure Battery issues

[crazymilk]

I have an aftermarket head unit in my T25 along with 2 x amps 2 x 6x9's and 1 x 10" Sub

I have a leisure battery hooked up to the main ignition battery via a Durlite VSR Spilt charger.
I seem to be having an issue that when the engine is not running the head unit and/or amps are cutting out and will not stay on (whatever the volume). As soon as I start the van there problem goes away and and everything is working fine.

I have checked all the wiring, both positive and earths - all seem good. I am using some heavy 18 gauge wire direct from the battery (with fuse of course) to the head unit, have the remote wires from the head unit to the both amps.

Anybody have any ideas why it keeps cutting out when the engine is not running?

[Jim San]

Is the LB any good?
Does it have any charge in it

[syncroandy]

Audio head units often have an 'ignition' and/or a 'key inserted' input which must be 'high' to enable the unit, you would need to wire these appropriately for your requirements. On a VW, battery + =red, earth=brown, ignition=black. The T3 has no 'key inserted' signal, so if you wanted that feature you would need to hunt about for a suitable CE1 ignition switch with an 'S' terminal (see recent thread on this topic).

[CovKid]

Thats a lot to be running off any battery on its own. Expect 30 mins running time even with the battery in the flush of youth.

[weegaz22]

Its probably something to do with the way the amps are wired, they usually have a signal wire going into them from either the headunit itself or the ignition that way they switch on and off and don't stay on when you get out the car and lock it up draining your battery, try it with only the ignition on, no engine running, if the amps are working then its probably coming off a switched ignition and you will need to change that to a signal wire from head unit itself or change it to something else

[crazymilk]

Thanks for the replies , very helpful so far.

The issue only occurs when the engine is not running, ignition on or of and it cuts out.
Leisure battery is new and has plenty of power.
Checked with a multi meter last night and split charger is working fine. 14+v while running
Engine running and no problem.

I have the remote wire from the head unit to the amps so thats ok.

I basically would like to to be able to run the stereo with the engine not running.

[CovKid]

How many amps is it all drawing, or summarise the total wattage. If the battery can't deliver what the amp needs, its possible it may be refusing to play. some circuits do that. I mention this as i never run my stereo other than when engine is running - and mine is only a basic one consuming less than 2 amps but left for any length of time (certainly an hour) it'll flatten my battery. Even a propex heater won't attempt to spark up if the voltage/current can't meet demand. Basic ohms law may solve this.

I'm wholly 12v so have to be very aware of what everything consumes. If I buy anything new, it gets tested via a watt meter. As a general rule, loud items or things that get warm demand a lot and manufacturers of 12v items have little to no incentive to factor in efficiency.

E D I T: To be honest, if camped I use a battery powered DAB radio or resort to the tablet for entertainment as I like to keep every bit of power I've got for spark on the Propex.

I suspect, if all is wired correctly, that the draw on the battery from head unit and amps combined is simply so great, it drags the leisure down to a level where the head unit or more likely amps, just cut out - depending on their construction. The power cables will also need to be beefy - all the way. You'd know for sure if instead of running just off leisure, you strap two batteries together in parallel. If it works then, you have your answer but totting up how many amps are needed to drive it all would be a more reliable indicator. You'd either have to seriously beef up the battery side (which brings with it additional issues and cost), or accept that you can only run the lot when engine is running, or at the very least bypass the amps when parked and just use the head unit if it has its own amp.

If you want to calculate it, use this page. http://www.ohmslawcalculator.com/ohms-law-calculator" onclick="window.open(this.href);return false;
Put say 12.5v in for voltage, and enter the total watts in the power box - that'll give a rough idea of your total amp draw.

A total of say 200 watts (as an example) would require some 16amps - not really viable for long even with two leisure batteries and like I say your present leisure battery may not be able to supply whats needed at all unless its being charged at the same time. Many fall foul of this. Hope that helps.

[crazymilk]

Thank you Cov - this is very helpful and much appreciated
I will check out the link you provided