Automotive Settings Maintainer - 9V Battery

[gathermewool]

I'm sure you've all seen these, but the question is: do they work?

I drive my 08 STI every few weeks, and want to put my battery on a maintainer for a week to revitalize it, but don't want to lose my setting while the battery is disconnected. I live in an apartment complex, so I can't just run the cables safely up to the car with out some one possibly tripping or vandalizing/stealing them.

Since my car shuts off the accessories, including the 9V lighter socket, I won't be able to use the 9V plug-into-socket job. If a 9V battery will safely maintain ECU settings for a week+, my plan is to buy a 9V connector from Radio Shack and fab up my own version of the "Settings Maintainer."

Thoughts?

 

[Chris142]

The 9V battery thing will save the settings long enough to change the battery out. If you take too long doing that it will drain the 9V battery and you will lose your settings.

No way that a 9V battery will last a week

 

[fsskier]

If you drive the vehicle long enough to fully charge the battery, what "revitalization" do you expect by putting it on a maintainer?

It seems that it would be way easier to start your car and let it run till warm then to connect a savings setter, then unbolt the battery, carry it in the house, charge, then reversing the process.

Remember, an underhood light, an open door with dome lights, etc all will kill your savings setter battery just about instantly.

Then, all is for naught!

 

[AuthorEditor]

Unless you're deep cycling that car battery, I don't see what good it would do to put it on a separate charger. In any case, can't you just hook up the battery while it is in the car? Is this for desulphating the battery? A car batteries life is usually pretty much maximized by just letting it charge up in the car in a normal manner. Normal starts use hardly any capacity so there isn't much danger of sulphation. On the other hand, if the battery is getting weak, maybe it is just time to replace it.

 

[Familyguy]

They work, but only for an hour or two, at best.

 

[The_Jeff]

I think you'd be better off getting one of those VW solar panels that plug into the cigarette lighter and wiring it in parallel to the 9v battery for some extra runtime. You want the battery there to soak up voltage transients though.

It's going to be wear on your battery tray, clamps etc to be always ripping the battery in and out of your car though.

 

[gathermewool]

Originally Posted By: AuthorEditor
Unless you're deep cycling that car battery, I don't see what good it would do to put it on a separate charger. In any case, can't you just hook up the battery while it is in the car? Is this for desulphating the battery? A car batteries life is usually pretty much maximized by just letting it charge up in the car in a normal manner. Normal starts use hardly any capacity so there isn't much danger of sulphation. On the other hand, if the battery is getting weak, maybe it is just time to replace it.


I bought the STI as a leftover at the end of '08, so the battery probably sat in the car for a long while on the show room floor. Now it sits for weeks in the winter before being driven (especially with all of the salt we've had on the roads latly.) When I do drive it, though, it's almost always for a good, long drive - 1-1/2 hrs to see the gf, 4 hrs to see the family, etc. The battery isn't bad enough to replace (free under warranty,) but noticeably weaker than it was last winter. I'm also not wasteful enough to kill the battery to get a free warranty battery, either.

With a multimeter, it still shows high 11.X Volts before I start'er up, but she cranks slowly - again, compared to last year. I have a batteryminder - the kind where the inverter plugs into the wall and is said to be able to desulphate a weak batter - and wanted to use it to "condition" the battery for a week maybe once or twice a year. Any suggestions on this would be great, too.

It wouldn't be a big deal if I lost the settings; I was just curious about how long a 9V battery might last, and if any one had done this. I would obviously set the dome light to remain off. If the capacity of the 9V is good enough for a few days, I can always parallel a couple of them together and try that as well. Again, I'm asking more out of curiosity than a gotta-make-this-work kind of thing.

 

[gathermewool]

Originally Posted By: eljefino
I think you'd be better off getting one of those VW solar panels that plug into the cigarette lighter and wiring it in parallel to the 9v battery for some extra runtime. You want the battery there to soak up voltage transients though.

It's going to be wear on your battery tray, clamps etc to be always ripping the battery in and out of your car though.


I was thinking of this, but New England and its overcast skies aren't very good for this kind of battery maintenance, at least not for the capital invested. This is why I have the battery minder (besides the small boat deep cycles I plan to charge for my dad before the crabbing seasons starts.) I figured a once or twice a year week-long "conditioning" was a pretty good plan. I'm always open to options, and always here to listen to others' advice

 

[The_Jeff]

If walmart still has those $15 lawn tractor batteries that's probably a good price/value option. I rebuilt a computer UPS with one... it was the same price as a much smaller gel cell. You could set it up on the floor and either (both?) charge it up driving around or use your whizbang gadget indoors.

(This is when someone will point out I don't want hydrogen gas in the house... I like to live on the edge.

)

 

[gathermewool]

That's a (edit: darned) good idea. At such a low charge rate would there really be very much H2 generated?

 

[andyd]

How big of a deal is it to re-set what you want? The battery in your car is like mine, mine just does not have the amp hrs. Playing the radio with the car off will kill the battery in less than 2hrs. But if I dont mess with it, it will start after sitting for 2 weeks. It has been fine all winter so far. I should prolly get a new one before my road trips.

Have you tested the alternator?

 

[gathermewool]

It's a brand new car, and the alt is putting out good voltage. If I DD the car, it starts fine every day. It's just a stock battery, nothing special. I'm not saying it's overly weak, but the car will crank very noticeably more slowly after sitting for a few weeks. I've already got the battery minder, and I'm interested to see if it does actually "condition" the battery. Unfortunately, the days of <20F days will become fewer as spring approaches.

 

[AuthorEditor]

To properly condition (desulphate) a battery requires charging at higher than normal voltage (probably around 14.2 volts) for a certain amount of time, while carefully monitoring gassing and water level. The problem is that you can't really do this with maintenance free batteries. This is why many deep cycle applications, such as boat batteries, use standard wet cell type batteries with screw caps with very heavy plates and lots of electrolyte capacity. Excess charging will generate hydrogen gas (explosive) and will evaporate electrolyte, which must be topped off at the end of the cycle. Do this in a well ventilated area and don't make sparks around the battery while charging! In a situation like yours I would just recommend putting it on a cheapo trickle charger every month or so for a day or two, or at least one day before you want to start it. No need to take the battery out of the car when charging. I personally feel that three years is about it for a regular car battery. Letting it sit uncharged for a year or two probably shortened its life substantially. You can get up to about 5 years on a very good battery that is used and charged regularly. I would recommend replacing it before you get stranded somewhere, and using the starter motor on low voltage will hurt the motor too.

 

[AuthorEditor]

I should have added that the conditioner will probably do some good even to a maintenance free battery. They can stand some boiling off of electrolyte as they have some excess. You will probably find some increase in capacity, which may be enough to let you limp along for awhile.

Also, 9 times out of 10, you will see improved performance if you clean the battery posts and the connections if it hasn't already been done recently. A little bit of corrosion on there can be the difference between a robust starter sound and a weak one, plus it also limits charging.

 

[gathermewool]

Originally Posted By: AuthorEditor
To properly condition (desulphate) a battery requires charging at higher than normal voltage (probably around 14.2 volts) for a certain amount of time, while carefully monitoring gassing and water level. The problem is that you can't really do this with maintenance free batteries. This is why many deep cycle applications, such as boat batteries, use standard wet cell type batteries with screw caps with very heavy plates and lots of electrolyte capacity. Excess charging will generate hydrogen gas (explosive) and will evaporate electrolyte, which must be topped off at the end of the cycle. Do this in a well ventilated area and don't make sparks around the battery while charging! In a situation like yours I would just recommend putting it on a cheapo trickle charger every month or so for a day or two, or at least one day before you want to start it. No need to take the battery out of the car when charging. I personally feel that three years is about it for a regular car battery. Letting it sit uncharged for a year or two probably shortened its life substantially. You can get up to about 5 years on a very good battery that is used and charged regularly. I would recommend replacing it before you get stranded somewhere, and using the starter motor on low voltage will hurt the motor too.


Thanks for the advice. If it doesn't start strongly in a few weeks when I try I'll give "conditioning" it with the battery minder a trial shot. If after another three-week or so stint it's not perfect I'll intentionally kill the battery and get a new one from the dealer for free. I hate to waste, but I think you're right. It's not worth possibly being stranded over the next cold weekend down at the gf's place.

 

[qship1996]

11.xx volts is basically a DEAD battery, completely discharged!!!!

 

[AuthorEditor]

My crude rule of thumb is that if your charged battery, after sitting for three days or less, and assuming the posts and connectors are clean, isn't spinning the starter at its normal speed then it needs to be replaced. If it takes 30 days before you hear a slow down in the starter, you may be able to nurse it along for a few more months. But, a good battery should be able to spin that starter right up even after sitting in your car for 30 days.

 

[gathermewool]

Originally Posted By: qship1996
11.xx volts is basically a DEAD battery, completely discharged!!!!


So you'd consider 11.xx = 11.99 to be dead? My battery wasn't at 11.99Vdc; I'm just using that as an example. It was closer to 12 than 11, but I used 11.xx because I'm not certain of the exact voltage.

Originally Posted By: AuthorEditor
My crude rule of thumb is that if your charged battery, after sitting for three days or less, and assuming the posts and connectors are clean, isn't spinning the starter at its normal speed then it needs to be replaced. If it takes 30 days before you hear a slow down in the starter, you may be able to nurse it along for a few more months. But, a good battery should be able to spin that starter right up even after sitting in your car for 30 days.


The last time I drove the car was this past Friday. If it's nice out I'll check the voltage and take her for a spin this weekend. Weather.com says it'll be in the 40s, so if it cranks slowly at all I'll know something is wrong. I still want to test out the "conditioning" claims of the batteryminder, but I'll be prepared to take'er out to pasture if need be.

Thanks again for the advice, guys.

 

[brianl703]

Originally Posted By: eljefino
(This is when someone will point out I don't want hydrogen gas in the house... I like to live on the edge.

)


Those batteries don't produce much hydrogen gas. If they did, you'd be adding lots and I mean LOTS of water to them.

 

[tonycarguy]

If the resting voltage is under 12.2v, the battery on its way to battery heaven. It's equivalent to leaving the headlights on overnight -- even if you recharge it, you don't know how much life is left because lead acid batteries do not like deep discharges. It is sulfated for sure. Don't take a chance, it will leave you stranded suddenly. Replace it.