Unexplained battery drains
 

Okay, not sure what is up with my SVX but it randomly drains the battery. It did it again yesterday and I've gone through about 6 batteries over the last year and a half because of it.

Most recently, it did it yesterday. I got a new battery in Nov, have been driving it just fine since then and even drove it too and from AWD Tuning last week without any issues and then yesterday it was dead as a doornail.

When Kuo was here, and we installed the new alarm and radio, I told him about it so he had some meter that measured the amount of drain on the battery when it was off and it read about .10-.15 amps which is pretty low and definitely shouldn't be enough to drain a battery in just a few days.

Any suggestions on what it could be?

Re: Unexplained battery drains
 

Assume your alternator is charging correctly...not too low and not too high, in 13.6-14.2 V range? 100MA to 150MA draw is considered a bit high by some but should take a few days to kill a decent battery. Suggest leaving the multimeter leads connected to the battery for at least 30 minutes and seeing what the draw is. I have in the past with a Dino Fiat pulled all the fuses to see if the draw dissappears and than added a couple back at a time to see what changes if anything. Yes, very time consuming. If with all the interior/engine compartment, aftermarket fuses out, there is still a significant draw, this points toward the wiring harness which can be near impossible (at least for me) to localize the problem.

Re: Unexplained battery drains
 

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For information on how to diagnose a parasitic drain on your electrical system, check HERE and HERE

Also make sure of any little things, like the trunk light going off when you shut the trunk light. I have seen them stay on, because you can't tell if its off when the seats are off. Just pull down a rear seat and check.


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Re: Unexplained battery drains
 

That's exactly what was wrong with mine. I found it when I had a pair of skis in the trunk and the seat down.
I just took the bulb out and problem solved.

Re: Unexplained battery drains
 

Check your ABS relay behind the passenger side headlight.
If its buzzing it will drain your battery quickly.
Unplug your power seat, it takes alot of voltage and will drain your battery if its trying to adjust your seat when you are not there.

Re: Unexplained battery drains
 

Thanks everyone, I have been reading through these responses and see if i can dig into this some this weekend. I did go check the trunk light and it was not on so that's one down at least.

Re: Unexplained battery drains
 

My suggestion is that .10 to .15 amp / hr is too much for a "dark power" drain. Let's bust down some basic math.. .15 amp / hr drain is 1.5 amp /hr for 10 hours. 3.0 amp / hr for 20 hours. 3.6 amp / hr per day.. If it sits for 5 days, that's 18 amp / hr , or, roughly 1/3 of it's capacity. Automotive batteries, are, almost exclusively, not designed to withstand that kind of cycling. An automotive battery is designed to crank an engine and then be immediately recharged to full capacity by the vehicles electrical system. They can easily last for 4 to 7 years... if they're never flattened.. Flatten it three or four times and they're toast, no matter how new they are. Dropping 30 % or more of a battery's charge, is absolutely damaging to it. As you noted.. six batteries in a year and a half.

Another consideration, is that, realistically, you don't get much warning when a battery dies. As most cars, with EFI and modern engine management, they start in a turn or three, there is often little warning of a battery's imminent demise. That's one of the reasons that alternators go at the same time as a battery. The alternator was working it's ass off trying to bring a flattened battery back to spec. Every time a battery is flattened by more than 10%, it takes a long step towards being junk. It's CCA ( Cold Cranking Amps ), and Reserve Capacity drop..

When I bought my SVX, the battery soon died. The previous owner had marked the install date on it, and it was less than two years old. I hit the web site of the local big box retailer, to source a replacement. At the end of the day, they would sell me a battery that fit, that had the ratings for the SVX, but they wouldn't give a warranty for it. To get a warranty for a new battery, I had to get one that that was rated to withstand being partially flattened over 400 times to 20 % capacity to have a warranty. It was also almost three times the price. It would seem that they knew that an SVX can be hard on a battery.

Check the specs...

http://www.canadiantire.ca/en/pdp/mo...l#.VPzzioHF9Q0

After sitting for over a month ( because I won't let it see salt ), alarm on, etc, it spun like it was just done running on a summer day.. and, at that time, it was -26 C ... -15 F..

It may well be, that the battery just didn't suddenly drain, but that it was just another battery giving up the ghost after being partially flattened one times too many, for a conventional battery. Also, as a stock alternator doesn't put out enough amperage at low RPM to charge with a full winter load ( seat heaters, rear window defroster, head lights, mirror heaters, high fan, headlights and running lights ), just because you went for a drive, doesn't mean that the battery got re-charged, especially if you were sitting at lights, in slow traffic, etc.. I've had mine die ( before I changed the battery), while running in the driveway, with electrical accessories running. I don't drive mine in the winter, unless the roads are clear of salt, and when I do, I make sure that it gets at least a 20 Km ( 12 mile ) run, with some highway miles near the end..

Personally, I'd hook up the multi meter and start pulling fuses until I found what was pulling 3 amp / hrs a day.. Something just ain't right, or, something is just an electrical pig, and needs a switch put on it.

My Harley is the same way.. Brand new, 2014 Sportster, on it's second battery, because it'll flatten itself in three weeks if not plugged in. Dark power and the factory alarm system are the culprits. Ridiculous engineering that a brand new vehicle needs to be plugged in when not in use.. Next battery will be lithium - ion. Taking the Harley rep to task about that on the showroom floor was priceless.. But, the same take away.. conventional batteries are quickly destroyed by a small load that causes partial flattening.

Re: Unexplained battery drains
 

Interesting battery lore...thanks

Re: Unexplained battery drains
 

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I agree completely. I have found that aging wiring and deteriorating, fraying connections to be the prime culprit when diagnosing for an electrical drain. Relays and switches are next

Back in 1992, the stock 95A alternator was adequate, when electrical demands were minimal (no high-powered stereos, additional lighting and circuits, etc.) New wires had minimal electrical resistance, fresh connections and solid grounds, etc

After 20 years of heat, corrosion and general deterioration, our aging wires are carrying less current than ever. A standard alternator output is based on an 750 rpm idle and the alternator output can be as low as 35% of rated output at idle in a hot state. For a stock SVX 95A unit, that translates to only about 33A. Our stock idle is lower than that.


http://www.subaru-svx.net/forum/atta...1&d=1425951582


For comparison a high-output 140 A alternator is designed to put out 55% of it's rated output at idle. That's 77A


Increased internal alternator temperatures from extended idling can also contribute to lower electrical system output. As the alternator’s internal temperature rises, the alternator’s output capability is reduced, due to increased electrical resistance. With heat, and an idle speed of 600-700 RPM, it can be as low as 35% of the full-rated output. With enough electrical loads engaged, it is easy to exceed the alternator current (amperage) output.

SVX alternators are prone to this due to their mounting location, their close proximity and to the engine's heat and minimal clearance to the underside of the hood. The under hood mat also partially obstructs the cooling slots on the top of the alternator.


As the engine/alternator speed changes, so will the current (amperage) output of the alternator. As a vehicle slows, engine/alternator RPM slows, and the current (amperage) output of the alternator may not be sufficient to supply the loads, the vehicle system voltage will drop and the lights may dim.

Dimming of the lights is an indication that current is being pulled from the battery. If the battery is in a low state-of-charge (discharged condition), the driver will notice a more pronounced dimming than a vehicle with a fully charged battery.

When high current loads (A/C, blower fans, rear defroster, headlamps, cooling fans, heated seats, power seats, power windows) are operating or cycled “ON”, the alternator’s voltage regulator can delay the rise in output. This effect, usually at lower engine speeds, can take up to ten seconds to ramp up the alternator output. This is done to avoid loading the engine severely. To increase the current (amperage) output, additional torque is consumed by the alternator. The engine computer ECU will ramp up engine/alternator speed in small steps so engine speed variations are not noticeable to the driver


At this time of year, the loads placed on our electrical system are greatest. Winter driving at reduced speeds, and the need to use current-hungry applications, such as heating/defrosting, rear window and mirror defrosters, lights, etc. are with us almost always in multiple combinations simultaneously. Cold temperatures also place extra demands on the starter/cranking system.

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Re: Unexplained battery drains
 

I am no way close to your understanding of the electrical system but, am sitting here with a new battery that is being drained (I keep it on a battery tender to stop that) and a starter that works intermittently. Repeated click, clicks, then catches and starts. Related? Testing both fuse boxes comes up with no drain. The drain started before the starter problem.

Re: Unexplained battery drains
 

Gene,
the battery drain and the intermittant no start need not be related.
Naturally when the battery is drained it will not start, but the drain could be completely a seporate issue.

Re: Unexplained battery drains
 

That click sounds like the infamous clickity click issue. Solved by adding another relay between the starter and battery. Many posts and threads on that issue

Re: Unexplained battery drains
 

As a follow up, I had battery drain and a starter with the click, click, click before starting problem. I tested and could not find any drain on the system (both fuse boxes). Replaced the starter with a rebuilt one and, all is well. Maybe an instant drain by the faulty starter or a hot wire connection corrected? I also replaced the positive battery terminal. Was clean but, corrosive worn below normal.

Re: Unexplained battery drains
 

That's definitely a possibility. Another issue I've been having is that I get in and turn the key...all the lights come on but nothing happens. No click or anything. I turn it a few more times and then the starter engages.

It doesn't start slow or anything, it sounds like a nice strong starter, it just doesn't do it the first couple of times that you try to start it.

I thought it was my ignition switch going south, but maybe not?

Re: Unexplained battery drains
 

The dreaded click click. Sound like a candidate for the relay by-pass surgery. :rolleyes: