Battery life when parked/stored

[Sahara]

Trying to get an idea of this to figure out if I need to have my '02 wired for a battery maintainer (previous owner moved the battery to trunk but there's no way to ground a traditional alligator clip battery tender at least as far as I can tell) or if it can sit alright on its own. Assuming no outside interventions and a healthy battery how long would you expect your '02 to retain enough juice to start the engine? It's already gone one week without any issues, as a few weeks ago I had it put up due to bad weather for almost eight days then took it for spin when the weather cleared. Unfortunately it's been garaged since thin I want to know if I'll be able to start when we get another break in the weather. It makes me nervous because the P/O's trunk battery setup not only disallows the trickle charger but I suspect there would be no place to ground jumper cables so if the battery drops below engine start levels I'd have to pull it out completely to charge it. 

 

ETA: I know I can google this for a generic answer but given that the 2002 has far fewer power vampires (alarm system, clock, etc.) than a modern car I suspect the answer will be fairly specific to the '02 or at least cars of its era. 

Edited November 30, 2018 by Sahara

[Healey3000]

Hi,

 

Mine sat for four months while I fiddled around with installation of an electric cooling fan and a few other things.  I had disconnected the negative cable through all this and was fully expecting to hear nothing when I turned the key.

 

To my surprise, the thing cranked over like there had never been a hiatus and the car fired up after a few cranks.  It's an AGM battery under the rear seat, about two years old.  ETX-30, I think.

[g_force]

Leaving it for a week or two at a time is no big deal.  I've left my non-power vampire cars for as long as 2-3 months. 

 

It is still better for your battery to use a tender if you're not going to drive the car regularly.  I think if you use a permanent connection type tender - not the alligator clips - you can mount it directly to the terminals on your battery.  The issue with attaching alligator clips to the terminals is that it could spark and blow up hydrogen your battery has off-gassed, thus literally blowing up the battery.  The permanent type tenders leave you with a connector on the end of a few foot long pigtail that you then plug into a corresponding connector on a wire from the tender.  There's no spark when you connect it, or at least if there is, you're 3 or so feet from the battery and at low risk of it igniting.

 

There's also the type that plug into your cigarette lighter.  I hear, but have no experience, that they work well.

Edited December 1, 2018 by g_force

[dlhoovler]

My car sits with the negative terminal off every winter inn an unheated garage, and it has never failed to crank and start in the spring (4-5 months). That's with a cheapo Walmart lead-acid 26R battery and no charger, trickle or otherwise.

-Dave

Sent from my phone.

[M3M3]

1 hour ago, Sahara said:

It makes me nervous because the P/O's trunk battery setup not only disallows the trickle charger but I suspect there would be no place to ground jumper cables so if the battery drops below engine start levels I'd have to pull it out completely to charge it. 

this is not making a lot of sense.  it should be easy to put the leads of a maintainer DIN plug wire permanently on the battery terminals and run somewhere easily accessible.

 

or if you are concerned with power draw, just put a battery cut off switch in the battery lead.

[Sahara]

31 minutes ago, mlytle said:

this is not making a lot of sense.  it should be easy to put the leads of a maintainer DIN plug wire permanently on the battery terminals and run somewhere easily accessible.

  

or if you are concerned with power draw, just put a battery cut off switch in the battery lead.

If I can connect the leads to the positive and negative terminals of the battery without having to find a ground in the trunk then it's not the issue I thought.

[2002#3]

A permanent lever-type disconnect between the NEG post and the NEG cable works for me and might work in your trunk battery.  Lever up when working on the car or when storing the car for hours, days, weeks, or months.  No battery drain and battery stays charged.

 

Larry

 

 

[esty]

2 hours ago, dlhoovler said:

My car sits with the negative terminal off every winter inn an unheated garage, and it has never failed to crank and start in the spring (4-5 months). That's with a cheapo Walmart lead-acid 26R battery and no charger, trickle or otherwise.

-Dave

same here

[NYNick]

I just went off the reservation and bought a Lithium Ion battery for the Tii. Guys are doing it with good success in the Porsche world and it's lasting them years with zero issues. It weighs about 3 lbs versus a regular battery that weighs 35 lbs, and will be under my rear seat. That's a lot of weight savings in a 2002!

 

I will keep you posted as to how it all turns out.

[John_in_VA]

I used a Battery MINDer for ~10 years until it died.  Replaced with the CTEK MUS 4.3 12V Battery Charger (56-864) -  https://smartercharger.com/products/batterychargers/ctek-multi-us-4-3/

[MikeD]

I have left mine sit for 7 months and it starts right up.  Have done this multiple times and have had no problems.

[TobyB]

Lead acid batteries self- discharge over time- how long is almost entirely dependent on the battery, and there's 

no way to know what it's doing inside there.  They keep getting better, too, as I get older.

I always try to get a floater on it every month or so, just for good luck.  And habit, too, 

as the more recent cars have draws that can't be turned off.

 

Lithium SHOULD last for a year+ in good shape.  Those things still scare me just a little bit-

I was blowing them up in little airplanes 10 years ago, and haven't quite gotten over it!

 

t