Battery dies in storage - Smart Car of America Forums : Smart Car Forum

Westfield 11 · 10-20-2008, 09:43 AM

Everytime we come back to LA from AZ the battery in our cabrio is too low to start the car. This time the whole dash panel was black. This happens when we leave the car for 5 to 6 weeks and it is becoming a real pain to pull back the carpet and wrestle the styrofoam footwell out of the car for access. Any tips on how to disable some of the "always-on electronics" that are draining the battery?

BTW where is the fuse box?

I went and permanently installed leads for a Battery Tender, but that is a band-aid and not a solution. Also how many times can the battery stand a total discharge before it dies? It doesn't seem to be taking much of a charge this time, I assume this is a warranty item?

**jwight** · 10-20-2008, 09:47 AM

Just my opinion, but use the battery tender. It's not really a band aid fix; most modern cars have "always on" electronics and there's no way around it. For comparison, our Corvette owners manual says 4 weeks max is all we can expect out of the battery if the car isn't driven. We put the battery tender on during winter storage.

rawlusÂ® · 10-20-2008, 09:49 AM

a battery tender is a solution, not a band-aid.
a deep discharge will usually require a day or two on a battery conditioner to get things right again, a jump start and the on-board alternator will usually not be enough to bring a completely dead battery back to fully-functional working order.
perhaps the easiest thing would be to purchase and install a simple battery disconnect. (assuming you have covered, secure storage for the vehicle)

Smartfor2guy · 10-20-2008, 10:12 AM

I Agree that the battery tender is a permanent fix. Other than that, a battery disconnect or cable removal is a possibility.

Dunerunner · 10-20-2008, 10:19 AM

Use the battery tender, don't use a battery disconnect. All on-board memory, clocks and ECU volatile memory will be lost using a disconnect. You can always wire a connection plug to the fluids access area and connect the tender there. Be sure to permanently connect at the battery and chassis ground.

Old smart · 10-20-2008, 10:48 AM

Quote:

Originally Posted by Westfield 11

... Also how many times can the battery stand a total discharge before it dies? It doesn't seem to be taking much of a charge this time, I assume this is a warranty item?

An automotive-type starting battery does not take kindly to successive re-charges from a low state. Its thin plates warp, "sulphate" and gas-off, and the active lead separates from the supporting grid during hard charging. I use two types of wet-cell batteries in my other pursuits: a "starting" battery and a "deep-cycle" battery, both switchable to the 12VDC bus. The starting battery produces a quick shot of high amperage and is for engine starting only. As long as the engine is running it gets topped before running low, probably never more than 10% down. It is generally kept isolated from the bus when not in use. The deep-cycle is the vessel's "house-battery" and is capable of nearly total discharge down to about 20% remaining, but at a lower amperage draw, and can be re-charged to full capacity hundreds of times. Its fewer internal plates are much thicker than a starting battery. It is always on the 12VDC bus. But for long periods of inactivity, the both get a float charge from an electronically regulated, "smart" battery charger. My use is marine, but the RV folks will know about this too.

If the dealer suspects that the battery is allowed to completely discharge time-after-time, they may not cover it under warranty. No automotive battery can tolerate that for long.

eqwalker · 10-20-2008, 11:17 AM

Agree with the above posts. A battery tender is, what I believe, to be the answer. I had to put one on my motorcycle as well as the Corvette during the winter months. Any longer than about 3 weeks is all I would chance without a battery tender, or starting it for a while.

fmaxwell · 10-20-2008, 11:51 AM

Having owned numerous battery float chargers, including the brand name Battery Tender, I can say without reservation, that I'd choose the Yuasa SmartShot any day:

It's simply a better battery maintainer, by far. It charges a low battery quicker. It maintains a charged battery better. It combats sulfation better. And this is coming from someone with three motorcycles and a boat.

For a good review, though a few years old now, see:

Five Battery Maintainers' Performance Compared

**jwight** · 10-20-2008, 02:29 PM

Can't remember who makes this one but it's inexpensive, compact and does the job: Corvette Battery Storage Float Charger, 12 Volt, Automatic

fmaxwell · 10-20-2008, 03:35 PM

Quote:

Originally Posted by jwight

Can't remember who makes this one but it's inexpensive, compact and does the job: Corvette Battery Storage Float Charger, 12 Volt, Automatic

I think that it's a Battery Butler:

BATTERY BUTLER - Battery Float Charger, Battery Load Testers & Jump Starters - www.batterybutler.com

As long as the battery is in good condition and fully topped up when you start, it should work okay.

The inexpensive float-only chargers (unlike multi-mode pulse chargers such as the Yuasa) can't really recharge a discharged battery, reverse sulfation, or do anything to revive weak batteries, but they are much better than letting your battery discharge continuously.