battery drain on excursion

Hello all, New to this site. Forgive me if this has been asked before, but i wasnt able to find the answer through a basic search? I own a 2002 excursion diesel 7.3 (2)Batteries are around 40 months old Viper remote start Milion d223b Jl audio 1000/1 Jl audio 12w7 Dc power 185 High Output alternator I had a local stero guy install a milion d223b head unit in my 02 Excursion a year ago. About two months ago i started noticing my batteries starting to get weaker when firing up my beast. On friday my beast was complety dead, i started googling for a parastic draw on my batteries after watching many videos on how to properly perform one i narrowed it down to my head unit. Once i unplugged the wiring harness the draw fell to around ~40 ma. I then cut the constant battery wire at the head unit to the wire hareness plugged in the head unit and checked again for the battery draw and it stayed at ~40 ma.. My question is do i need to have the constant battery wire connected? I temporily connected the constant battery wire with the backup 12v wire and now the radio only turns on when the lights are on and all my presets are gone? Please help out this noob.......love this site. Thanks in advance. 02EX

Your batteries may simply be at end of life. Have them tested. I assume your HU turn off with ign or acc off (ie, so const +12V and switched +12V are not BOTH getting +12V when supposedly off "off".) 40mA IMO is high but, but some alternators alone consume 12mA just sitting there. If your charging voltage at the battery terminals sits between 13.8 to 14.4V (preferably 14.2-14.4 for good battery life) at typical RPM & loads, then your alternator is probably charging ok. I assume you are using a battery isolator? Permanent paralleling of batteries shortens their life.    

hi, for the current draw, i agree 40mA may seen a bit high. disable/disconnect the remote start and recheck. the draw may reduce slightly. as for the batteries in parallel, the big 3 automakers here wire the batteries that way on the diesel powerplant models. mark

I know of older duals that series-switched 12V diesels for 24V starters, but parallel 12V for double the current into the same power 12V starters is simpler as well as being less than half the battery "strain", tho they should still follow normal battery isolation when not being used - even if they don't do it as OEM. Maybe OEM have matched batteries or found that their batteries last long enough... But one bad battery will bring down a good battery so vigilant monitoring is suggested (eg, weekly voltage - & temperature tests if AGM), but auto-isolation overcomes that and means you can test each battery's voltage and hence determine if partly discharged or collapsing cells, or even a bad alternator.    It still unnerves me when I hear of permanently paralleled AGM batteries that do not have temp sensing or other monitoring or alerts - even if people aren't dumb enough to mix new with old.

oldspark wrote: Your batteries may simply be at end of life. Have them tested. I assume your HU turn off with ign or acc off (ie, so const +12V and switched +12V are not BOTH getting +12V when supposedly off "off".) 40mA IMO is high but, but some alternators alone consume 12mA just sitting there. If your charging voltage at the battery terminals sits between 13.8 to 14.4V (preferably 14.2-14.4 for good battery life) at typical RPM & loads, then your alternator is probably charging ok. I assume you are using a battery isolator? Permanent paralleling of batteries shortens their life.

Here is my update.....on my parasitic draw. Just to be safe I replaced both batteries yesterday and i didn't have any starting issues this morning. The Hu is off when the ign or acc is off. The ~40 ma draw seems to be consistent with what i have been reading on the net. To my knowledge im not using a battery isolator? 02EX

Ween wrote: hi, for the current draw, i agree 40mA may seen a bit high. disable/disconnect the remote start and recheck. the draw may reduce slightly. as for the batteries in parallel, the big 3 automakers here wire the batteries that way on the diesel powerplant models. mark

Ween, I will test my draw with disabling my remote starter and alternator this weekend. 02EX

Had family visit me for the week, so i apologize for going idle on this thread. I still need help.....Hu will only power on when I turn on my lights? How do i get around that without connecting the constant 12V wire (which was causing my parasitic draw). 02EX

So it is the HU's const +12V that is drawing 40mA when the HU is off with the HU +12V switched input off or disconnected? If so, the HU is bad or a bad design or there is some other wiring fault causing this. When the const +12V is cut, the HU will lose its memory. (Exceptions are when the ON switched +12V can also hold memory, or if the HU has some internal capacitance or battery to hold the memory for a while.) Memories should only take a few mA if that. My Alpine draws ~120mA with both const & switched = 12V so I can't leave the switched +12V permanently oonnected. Because I want IGN independence, I wired ACC/IGN +12V thru a diode to a relay coil to switch switched +12V to the HU. Also the HU's remote on (output) via a diode to the same relay. Hence once the HU is switched on (with IGN), it will stay on until turned off at the faceplate. (I also intend to fit switches to return to normal "IGN off HU off" operation, and one to bypass the need for IGN altogether.)

oldspark wrote: So it is the HU's const +12V that is drawing 40mA when the HU is off with the HU +12V switched input off or disconnected? If so, the HU is bad or a bad design or there is some other wiring fault causing this. When the const +12V is cut, the HU will lose its memory. (Exceptions are when the ON switched +12V can also hold memory, or if the HU has some internal capacitance or battery to hold the memory for a while.) Memories should only take a few mA if that. My Alpine draws ~120mA with both const & switched = 12V so I can't leave the switched +12V permanently oonnected. Because I want IGN independence, I wired ACC/IGN +12V thru a diode to a relay coil to switch switched +12V to the HU. Also the HU's remote on (output) via a diode to the same relay. Hence once the HU is switched on (with IGN), it will stay on until turned off at the faceplate. (I also intend to fit switches to return to normal "IGN off HU off" operation, and one to bypass the need for IGN altogether.)

oldspark, It's definitely the const +12V wire that is causing my parasitic draw (see picture below)I temporally connected it again and my meter read ~5.21 (please advise if I set the centech multimeter correctly) Here is picture with const +12V connected. and here is a picture of the the const +12V unplugged. Is there a way I can get around this parasitic draw while still keeping my pre-sets and preferences on the HU? It also sucks having to turn on my lights for the HU to power on the way i currently have it connected? btw as you can tell I'm a bit of a noob with the lingo, pictures or videos for me are a big plus. Thanks 02EX

I question the +ve lead socket. Usually that furthest left socket is unfused for 10A, or in your case, 20A. The mA ranges use the normal (fused) socket but in your case, the 2nd left "fused mA" socket. The proper socket can make a big difference. IE - a DMM spec'd with 1% accuracy on a 20A scale can mean 1% of 20A = 200mA which means your 5.21mA could be anywhere from -195mA to 205mA. If the 5.21mA is correct, then the drain is ok. 5mA is typical of a LED or less, and 1/50th of a typical Automotive relay or 3W bulb. IOW negligible. (Even some alternators consume over 10mA "parasitically".) And no - you can't get around that parasitic draw. That is the current required to keep the HU's memory and any supervisory stuff (USB connections etc). IMO HUs should have non-volatile memory (that does not require power) for at least tuning (with a reset button). The only issue is if that draw varies - eg, my Alpine which when off draws ~120mA-140mA if BOTH const & switched +12V are connected but only a few mA if only one is connected. Hence I can no longer wire BOTH to +12V like I used to do, and hence the relay that connects the switched to const (whenever it is energised by IGN or ACC +12V, or a manual switch, or the HU's remote output).