Battery and alternator questions

[trollbait]

Over the winter I've had the battery in the HHR die on me twice. So I'm planning ahead on what to replace it with, but I have some questions that my google-fu isn't handling.

First of all, the HHR battery is mounted in the rear with the spare tire. It is vented to the outside. How much does a battery regularly vent, and hazardous are the fumes? Where do batteries without hook ups for venting tubes vent from? Are there holes that vent lines can jury-rigged too, or does the entire thing need to be vented?

Since I EOC, I would like to get a dual purpose or deep cycle battery. Finding one that has the vent hook ups as been problem, and space next to the spare might be tight. An AGM battery might be ideal, but they require a lower float charge, and I haven't had luck on finding out how to adjust it, if possible, or what exactly the HHR is even putting out.

If, for what ever reason, I'm stuck with an OEM battery, would using two to spread out the strain of FASing be worth the effort?

[Jay2TheRescue]

Generally battery gasses are not a problem, unless there's something wrong with your alternator and its overcharging the battery. You can get a gel cell for the car, they are sealed and don't have vents, but they are expensive. Just about any lead acid battery is going to require vents.

[trollbait]

With what I knew, I wasn't to concerned with fumes. I could always seal up the cover of the spare well and drill a couple of vents. Just better to get some other opinions.
I took a look yesterday and the vent line was already broken. Not having seen a new battery, I don't know if it was a part of the car, or of the battery the snapped.
An OEM battery starting cost starts at around a $100. Like the ecotec oil filter and Prius 12 volt battery, the price is likely do to the vent hook up and limited specific application for the battery.
The hassle now is finding another battery that meets my required specs without going through a car model search.

[theholycow]

$100 isn't too bad. Around here you pay $65 at Walmart or $80 at a parts store for a cheap battery.

[trollbait]

They range up to $150, and I found an Optima yellow top on Amazon for $172.

[trollbait]

Just remembered the scangauge has a voltage display. The lowest reading on it is 13.8vlts, which is the highest an optima can take as a float charge. And I'm not sure when the voltage climbs if it the system is ramping up into charge mode for the battery.

[JanGeo]

Be better to figure out why you keep killing batteries than to just be replacing them. Most lead batteries are not going to vent anything if they are below 14.25 volts and if you find that your dead batteries are running dry then check for over charging. EOC is going to be draining the battery and depending upon how long it can add up to a lot of amp hour cycling of the battery. Might be a good idea to measure the draw under those conditions.

[trollbait]

This is first battery that has given me problems in a vehicle that is regularly EOCed. This is the second battery that has been placed in the car. The first was replaced under warranty do to a bad cell. That was before I took possession of the car 3 years ago.

I'm sure EOCing is shortening its life. It is just a starter battery, and not meant for repeated deepish cycling. At moment, I'm not worried about the battery stranding me. The couple times it left me in a jam, may actually have been the computer overriding the ignition. It has a battery saver mode that prevents the starter from firing up when the battery is below a certain threshold, 10 volts I believe. I've backed off EOCing to be safe, because I have seen the voltage dip that low.

While I don't feel pressed to replace it now, I want to be ready for when the time comes to replace it with a dual purpose battery that can shrug off the EOCing. The first hurdle is the venting. Not that I'm worried about fumes. In fact, I just noticed the vent line is broken, and may have been since I got the car. The vented requirement just eliminates the ease of basic part look up menus.

The second hurdle is the float voltage. I have found the optima product that will work. Except it, and all AGM batteries, can't tolerate the higher float voltages that car charge systems equipped with traditional lead acid batteries might put out.

[GasSavers_Erik]

How long do you EOC? I think you'd need to go at least 5 minutes with your headlights on to drain the battery down low enough to shorten its life.

But if you live in the mountains, then a 5 minute+ EOC is very possible...

[Jay2TheRescue]

If you're going down a mountain, you're better off to DFCO down the mountain. Battery is not depleted, and the engine braking helps keep your brakes from overheating.