Rapid battery drain after not using car for 3 months

[Kumar 1]

I was out of country for 3 months and when I returned the car battery is dead. I took the battery out, charged it overnight (using CTEK 5A 8-Stage battery charger) and it charged fine. I used the car for the day but 2 days later the battery is again low and won't start.  I charged it again today for few hours until it showed ready on charger and was able to start the car but few hours later it wont start again.

Not sure if the battery is gone bad now and needs to be replaced or I need recharge it few times to resurrect it.

The battery is about 3-years old (Bosch DIN75)

[LemonHunter 583]

Easy check to confirm, fully charge, whack it in the car, put a multimeter across it, crank it over, if the voltage drops under 10 its almost certainly buggered, below 8 for sure. 

[M3AN 4016]

Or disconnect it, fully charge it and check the voltage 24h later... if it's dropped, even by a few volts, it's dead.

I'm dealing with the same situation. PITA.

Edited October 26, 2019 by M3AN

[LemonHunter 583]

So I can get euro batteries like 30% cheaper than retail, good brand too, hit me up with your DIN

[LemonHunter 583]

Like this case DIN75

Oddly I can only get a DIN73 or a DIN77

What are they normally? $400 to $500

I can do $220 for a Neuton Power DIN77

[M3AN 4016]

No 65's?

DIN65ZL Automotive 680cca

[LemonHunter 583]

DIN66 Same dimensions I think but 620cca

$190

https://yhipower.co.nz/catalog/neuton-power---euro-auto-102336.htmx

Edited October 27, 2019 by EUROLESS

[M3AN 4016]

I'm evaluating mine in detail this weekend (328 went from full to dead flat in 120 mins on Thur ?). Car is only drawing 0.035 amps when off so that's okay. But it only dropped 0.1 volts last night when disconnected so further investigation required tomorrow.

I did get a Bosch 65/680 online locally for $250 just the other week (for the M3) which I think is a pretty sharp deal. What's the shipping for that Neuton in NZ? It might be fine for the 328 and probably better than a Repco.

[LemonHunter 583]

Shipping is from the depot closest to you, so probably $10ish

I'm still a fan of load testing, sometimes without a load they settle in the low 12's happy enough. 

Measuring internal resistance helps, but load test is the true test. And the load of starting a car is a pretty good one. I usually test batteries as close to their initial current rating as I can. 

[M3AN 4016]

My weekend diagnostics are suggesting it's the alarm draining the battery... and alarms are terrible to diagnose... ?

 

[Kumar 1]

42 minutes ago, M3AN said:

My weekend diagnostics are suggesting it's the alarm draining the battery... and alarms are terrible to diagnose... ?

 

So how do you diagnose whats draining the battery ?

[Gaz 1061]

E61 have energy diagnosis available via ISTA. Making sure the battery is correct for the car and registered is the first step and then seeing where the voltage drain from

[LemonHunter 583]

1 hour ago, Kumar said:

So how do you diagnose whats draining the battery ?

One method is to put a multimeter in series with the battery and start pulling and replacing fuses, in theory one of the fuses will stop the drain, then you can further diagnosis that circuit. 

[M3AN 4016]

5 hours ago, Kumar said:

So how do you diagnose whats draining the battery ?

As Charlie says, using a multimeter to measure current draw from the battery. If you search for "measuring parasitic loss" you'll find heaps of helpful info. In my case the alarm was (apparently) easy to isolate because with everything off my current draw was acceptably low (0.035 amps) but the battery drained rapidly when the alarm was set.

Now, it could also be something connected to the alarm, not the alarm itself (e.g. door lock actuators, glass break sensors, siren, etc, etc) but I've yet to dive into that. I use a battery isolator so for the next week or so I'm opening the trunk, setting the alarm (to lock the doors), isolating the battery and then closing the trunk. This way the doors are locked, the battery can't drain and I can still open the trunk.

More fun next weekend... ?

 

[Kumar 1]

On 10/27/2019 at 11:12 AM, M3AN said:

Or disconnect it, fully charge it and check the voltage 24h later... if it's dropped, even by a few volts, it's dead.

I'm dealing with the same situation. PITA.

I have fully charged it and 24 hours later the voltage dropped to about 10.7v (and it remained same even after 48 hours). I tried the "recond" option in the charger which looks like a desulphation process but don't think it has helped much. I will charge it again today and test again.

[M3AN 4016]

10.7v is stone cold dead.

If you have a charger with a very low amp output (like 2 amps) then set it to that setting and let it run in recondition mode (will need to charge to full first). It'll take a while but it's worth a shot.

 

[Kumar 1]

I got CTEK MXS 5A 8-Stage battery charger. Not sure if you are saying I should try using a lower Amp like CTEK 0.8A charger ?

[M3AN 4016]

No, don't get another charger. It's just that some chargers allow you to select the amount of amps to provide and occasionally using the lowest setting to charge will trickle it back to life.

Give it a couple of full rejuvenation cycles (until the charger tells you it's finished), that's probably the best you can do at this stage.

 

[Eagle 1662]

Try connect another 12v car battery source to it via jumper leads and leave it for 1hr to give it some surface charge before charging