Battery topping in garage with no AC power

[JHZR2]

Hi,

My truck is parked in a garage with no chance of having AC power available for a battery maintainer. Solar maintainers are not a good option there either. My thought is that if I took a low self-discharge lead acid battery, and connected with fused alligator clip leads, then there would be double the stored capacity, meaning that parasitic loads cannot take my battery down as low, even if my truck sits for a month and a half.

mismatched batteries would ensure that the stronger reserve battery would keep the other one topped up, and I cannot imagine that, say a 10A fused lead would be strained, even if one battery had a volt difference versus the other.

I can easily take the reserve battery home now and again and recharge it fully.

Any issues with this idea?

Thanks!

 

[Bluestream]

If you can take the reserve battery home for charging, why not just take the main battery home? Or take it out all together and leave it where it can be charged...

 

[JHZR2]

Because often I use the truck every week to every other week, but it is also sporadic. It is a hassle to have to unbolt the battery, and the two cables, versus a quick alligator clip and a battery with a handle. Given that it will never really cycle, and will always be in controlled environment, I believe it will last, and Im willing to pay for convenience here.

I may even look to get one of those 20 year-rated telecom UPS batteries...

 

[brianl703]

No windows in this garage at all? If it does have a window, stick a solar charger in the window and extend the cord to reach your truck.

 

[brianl703]

Originally Posted By: JHZR2

I may even look to get one of those 20 year-rated telecom UPS batteries...


I don't think that will pay for itself.

 

[tinmanSC]

Have you had trouble with this in the past?

 

[JHZR2]

Yes, I have had the battery go flat once because of the sitting (for a few months), and one other time I had a shorted cell, likely due to the same thing.

I have, for example, a used group 49 battery (big diesel) which still holds charge and is in good shape, that I could use if it would do the trick. I think it would, but are curious what others think...

 

[fdcg27]

I have had vehicles sit with no effort to maintain the battery for a couple of months, and they crank right up when I need them.
For example, I just swapped the '99 Accord for the BMW Saturday, and it had been sitting in the garage for at least ten weeks, and it started with no effort at all, albeit in warmer weather.
I did make sure that I would be driving it at least twenty brisk miles when I first ran it, to help evaporate moisture from the oil, as well as to fully charge the battery.
The M1 15W-50 comes out next week, incidentally, and will be replaced with 0W-30 AFE.
If the thing will never sit for more than six weeks, and if it has a good battery in it, I don't think you'll have any problems.
Just run it long enough when you do use it to bring the battery to a full charge, and I really don't think you need worry about excessive self-discharge, or parasitic losses to the vehicle itself.

 

[JHZR2]

I always do, but after a while (last battery I think had 6 years on it), they go bad. It is six years of very little actual usage. That is because while the vehicle will fire right up no problem, the battery chemistry IS changing. A car will crank with a battery that has an OCV of 12V. Maybe a diesel wont start, but a gasser should crank and start if in half decent chape.

Im looking to do a bit better given the usage of the battery. If kept on a float charge, garaged, etc., the battery would likely last much longer due to its use profile.

 

[JHZR2]

Originally Posted By: brianl703
No windows in this garage at all? If it does have a window, stick a solar charger in the window and extend the cord to reach your truck.


Actually no. And the roof angle (flat roof) and trees around make it not very good for solar.

Thats why I figure doubling stored capacty means that the actual depth of discharge due to self and parasitic discharge will be half as much, and the chemistry will remain in much better shape. Since it will be at optimal temperature and a very narrow voltage range, far better maintained by using a second (larger) battery to keep it topped up, it should stay in better condition longer.

Not sure if power electronics control would be smarter though

 

[fdcg27]

Six years is not a bad lifespan for a battery.
Are you going to spend more on a second battery than you'll save extending the life of the vehicle battery?
Also, consider the hassle factor of having to tote the second battery home for periodic charging.

 

[Bluestream]

Just take a spare battery with you when you use the truck. If its gone dead, jump it. It should go 60 days at least before going dead, or its on it's last legs anyway

 

[Eddie]

I think a good battery will maintain more than enough charge to sit for 6 weeks in NJ and start the engine.

 

[raaizin]

Depends on the car. I have an 2007 Audi A6 and if I dont drive it once or twice a week the battery will die.I had a 1996 corvette that would stay parked for 2-4 weeks at a time especially in winter and never had an issue.

 

[wrcsixeight]

A Flooded battery will self discharge 12 to 15% a month at an average od 75 degrees F. Thr higher the temp, that faster the self discharge. The older the battery, the faster the self discharge.

AGM batteries like Odyssey, Diehard Platinum, and Optima will self discharge 2 to 5% in the same time frame.
Odyssey will have ~25% more capacity than a 6 pac style battery of the same footprint.
When You park the vehicle, Disconnect the negative cable from battery. An AGM battery can last well over a year like this.

You will lose your radio presets And the computer might take a little while to relearn your engine.

 

[fdcg27]

I don't mean to be critical, but manufacturers intend that a car should be able to sit for a month or so and still start.
Nobody wants to leave their car at an airport for a week or two, and then come back to find it unable to start.
Could you have a bum battery, or a short to ground somewhere in your car?
The car should be able to sit for some weeks and still start without issue.

 

[Chris142]

I'd take one of the cables off when it's sitting unused. No draw that way.

 

[Pop_Rivit]

Originally Posted By: JHZR2
Hi,

My truck is parked in a garage with no chance of having AC power available for a battery maintainer. Solar maintainers are not a good option there either. My thought is that if I took a low self-discharge lead acid battery, and connected with fused alligator clip leads, then there would be double the stored capacity, meaning that parasitic loads cannot take my battery down as low, even if my truck sits for a month and a half.

mismatched batteries would ensure that the stronger reserve battery would keep the other one topped up, and I cannot imagine that, say a 10A fused lead would be strained, even if one battery had a volt difference versus the other.

I can easily take the reserve battery home now and again and recharge it fully.

Any issues with this idea?

Thanks!


Put a working battery in the truck and you don't have to worry about a jerry rigged charging system.

I let my pickup sit for months at a time without an issue. I last ran it in early September; I started it and used it last weekend after almost 2 months. No battery issues whatsoever with the Interstate battery that I installed in April.

 

[meep]

1. wrcsixeight is dead-on. i'd call this recommendation #1

2. a second paralelled (alligator-clipped) battery, assuming it's a flooded cell, will discharge at the same rate, so you might as well forget the wires and just jump-start with it, then charge it.

3. stock ECU memory load should not be enuf to kill the starter battery... self-discharge is your main worry, unless you have added unswitched loads to the vehicle.

4. using a higher capacity starter/deep cycle combo battery can work wonders because of higher AH capacity and ability to cycle lower. Did this in an old RAM1500 van that was hard to start/run in the northern winters and it was GREAT.

5. I'm dreaming of a used mower engine, an internally-regulated GM alternator, belt drive... small 50amp charger to prep the battery with prior to starting car. or go to harbor freight and buy one of those 700 (900?) Watt 2-stroke gensets and a basic old-school battery charger, they've been on sale for under $100. $120 problem solved.

M

 

[wapacz]

Get a battery isolator and switch it off when you leave. Other than that maybe a marine starting battery which is a cross between a deep cycle and a marine battery.