How long should the starting battery hold its charge?

[SoquelDude]

Hi!

I'm recovering from foot surgery and haven't started up my Vanagon for over 2 weeks. The van has a GW LiFePo4 house battery with a Wagan EL7410 charger. The radio and all interior lights run from the house battery, and the exterior lights run off the starting battery.

I asked my wife to start the Vanagon up today and it was dead. Yup, 2 weeks is a long time between charging cycles, but I would have hoped the starting battery (about 4 years old) would have enough power to start the engine.

What are other folks' experiences with this?

BTW, both the starter and alternator are fairly new. What other draws are there on the starting battery when it's not charging?

Thanks!
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'90 Vanagon Westy GL, AT, EJ22E conversion (1993 2.2L Legacy Engine)

[Shonandb]

A battery in decent shape with no parasitic draw should hold a charge for more than a month. I leave my car at long term parking at the airport for 3 weeks to a month at a time and it starts no problem, even in the winter. Was a light or something left on?
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76 Westy with a 2.5L Subaru SOHC + Vanagon (010) Automatic Transaxle
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Previous 1973 Panel Bus:
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[zerotofifty]

A lead acid battery with no load on it should have ample charge after 2 weeks to start a car.

You have a problem. 1. battery not being fully charged, fault in charging system, 2. a bad battery, 3. a fault with your starting system 4. and/or a parasitic load that is discharging the battery. 5. Bad battery connections

Number 3 can be checked by jumping the battery with a good battery, if she then starts, then assume the starting system is good

Number 2 can be checked by charging the battery, then do a load test on it after some time.

Number 1 can be checked by measuring the voltage output of the charging system


Number 4 can be checked with an amp meter, or even a light bulb in series with the battery terminal to battery cable

Number 5 can be checked with a visual inspection, look for dirt and corrosion, loose clamps on battery posts

A good battery should be able to sit for a couple months and still start the car assuming no parasitic loads, and it was fully charged prior, everything in good shape.

[Ahwahnee]

Yes, a proper starting battery shouldn't have a problem being unused for 2 weeks... or two months... or a year (if there's no draw).

You can have it charged and load tested but quite possibly it cannot come back so you're left with getting a new battery then testing for phantom draws.

How old was the subject battery? How cold was the garage?

[dhaavers]

Aftermarket stereo?

Voltage gauge?

USB charging port?

I could keep guessing, or maybe provide a list of accessories in your van…

- Dave
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86 White Wolfsburg Westy Weekender
"The WonderVan"
<EDITED TO PROTECT INNOCENT PIXELS>

[jimf909]

[tdivan82]

Dead in two weeks indicates a problem. Battery health meters are inexpensive, to rule out a failing battery. Modern cars with all their computers and electronic gizmos consume a little current even when off. Older vehicles like this however, should have almost no parasitic loads.

One way to troubleshoot this, is to put your multimeter into Current mode (Amps) in-line between the battery negative cable, and the negative terminal. There should be no more than a few 10's of milliamps, at most.

If you have hundreds of milliamps, start pulling fuses one by one, and watch the meter. If you find one that causes a large drop in current, you've found the guilty circuit. Identify what's on that circuit to find the culprit. You can disconnect devices from the circuit one by one while watching the meter until you've found it.

As mentioned, aftermarket stereos are a frequent cause. I've also seen engine swaps where the ECU was incorrectly run to constant power instead of switched. Failing electrical components can also sometimes have a constant draw, saw that with a seat motor once in a newer VW. But yeah, first find which circuit is causing it, then which device on that circuit.
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- George
'82 Westy TDI

[kamzcab86]

While everyone is correct, 3 years is the average life of a modern starting battery (average; there are exceptions!). So, at 4 years, yours is at, or nearing the end of life, at which time its ability to hold a charge decreases. You can try to charge it and load test to verify.
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~Kamz
1986 Cabriolet: www.Cabby-Info.com
1990 Vanagon Westfalia: Old Blue's Blog
2016 Golf GTI S
"Real knowledge is to know the extent of one's ignorance." - 孔子

[SoquelDude]

[SoquelDude]

[SoquelDude]

[SoquelDude]

[SoquelDude]

[zerotofifty]

That little light above the glove box once and a while gets bumped into on position in my van, the result can be a dead battery. that light has probably be accidentally turned on more times than intentionally. I ought to remove the bulb, but I am lazy.

[4Gears4Tires]

My BMW e39 540i has a large AGM battery. It regularly goes 6 months between starts. Poor car just gets ignored. Even after 6 months of sitting outside in the cold, it turns over that v8 no problem. I have no idea how old that battery is either.

I'd be looking into electrical drain if a battery only lasted a month.
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'87 Syncro Ferric Oxyhydroxide Superleggera Edition
'85 Westy Sciuridae Domus Edition

[jimf909]

[jlrftype7]

As an a side note, I don’t know WHY our battery is still testing good after being installed in November 2018, but there it is… I’ll take it..
NAPA battery , stock group #.
Let us know what you find with your electrical system.
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'68 Westy- my first VW and vehicle/Bus- long gone.- sold it to a traveling Swiss couple....
'67 Type 3 Fastback, my 2nd car- gone
'69 Semi-Auto Stick Shift Beetle-gone
2017 MINI Coopers, our current DDs
‘84 Tin Top - Hilga....Auto

[MarkWard]

It has been my experience that starting batteries seem to die without warning compared to the old days. In the old days, you could "hear" a weak battery. Now I've had a battery start the engine in the morning and next restart be stone dead. No audible warning at all. These were all batteries that had some years on them. Charging and cranking systems tested fine. This would include my wife's Camry, our Dodge Durango and even the Vanagon.

[dobryan]

This will not solve your problem but I find that putting one of those small 10W solar panels on the dash when I am not using the car/bus for a while really helps keep the battery topped up. Of course this assumes it is parked outside and not facing North...
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Dave O
'87 Westy w/ 2002 Subaru EJ25 and Peloquin TBD

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[Red Ryder]