So I am looking for a very dependable and reliable battery maintainer for a vehicle that is being stored all winter, and I will have very limited access to both the building and car.

I don't want to lose everything, and want to keep the battery going over winter I just got it going. I hope to drive it here and there, but on a daily basis I won't be able to oversee the operation so to speak.

I remember a member here lost everything from one of these devices, that was several years ago and hopefully technology has improved.

I've been running the Battery Tender brand of battery maintainers for many years. Between my lawn mowers, my cars and my son's car, I currently have 9 Battery Tenders running.
Never ever had an issue with the Battery Tender brand.

In that situation it woyld be better to disconnect the battery and bring it home.

While I haven't had anything close to an overheating or fire problem - knocking on wood as I type this - Rhinodart's fire photos chill my spine.
I've had as many as 7 maintainers going at once.
Best of the ones I've bought were Schumachers & Duralast (AutoZone).
This year I've just disconnected the 2 Road Runner batteries, but am running maintainers on the 2 later models that have computers.

I have a battery tender .75 amp unit on my sportster, my fury I've had need to start it about every 2 weeks so I can pull it out and work on other stuff in my garage..... The last 2 years I've been able to park that at moms house in her garage, and with no charger/maintainer at all it started right up without a jump after sitting 6-8 months...

For about 10-12 years I’ve been using battery tenders and BT jrs. Lately one crapped out (sort of) by no longer going into full float. I just switched to NOCO Genius 1s and so far so good. I like wall warts as opposed to corded on both ends.

I had been using Battery Tenders for many years until I had one short out and burn up. The case was totally warped and very hot.
I called corporate and reported the issue, they didn't seem very concerned sent me a new one.
Then a week later their chief engineer called me in a panic and wanted me to send the defective unit back for evaluation but it was already tossed into the dumpster.
Then I learned about desuflating process, won't use another Battery Tender gave the new replacement unit away. And I upgraded to the Battery Minder, great investment.
Here is the one I bought from Amazon..

Just my $0.02...

https://www.amazon.com/BatteryMINDe...y-Motorcycles/dp/B00D7HZ6FC/ref=sr_1_28?

I still use Battery Tenders but do not put the negative clamp on the battery. I leave the ground connected to the battery and put the negative on a clamp on a body ground. I have had some issues with battery tender not working correctly if I put both clamps on the battery...

I totally agree. Hopefully we won’t be reading about this in another thread down the road. Ask Rhinodart.

Put it in a small fire proof box.

Bring the battery home and keep it in a warm spot is the best thing you can do. Stored right it should hold a charge for a long time.

I have let past old cars I've owned sit from October to March or April and the battery still had enough juice to spin the engine over with plenty of speed. If you have batteries that need to be put on a charger several times a year you need to get a better brand of battery when those are used up.

I just unhook the battery on my B'cuda and leave it in the car all winter. Usually just hook it up in the spring and start the car. My 18 Mustang I start once /month during winter....too many computer relearns to disconnect it. At work we had a pole barn full of cars with Battery Tenders on them.....Fire inspector came through and said Had to take them all off.

I’ve never fooled with one and I get at least as long a life as the battery is rated for. U hook the cable for the winter is all I do. always hear about issues with these tender things. My latest battery is an odyssey and it the best battery I’ve ever had. Claim is it will go two years without a tender and not lose a beat. Both springs so far it fired the car like lightning first try.

I’m no exprert, but I think it’s a “vintage Mopar vs. modern Mopar thing.”

Vintage Mopar, I suspect can do well without a tender while in winter storage.

Modern Mopars have a continual micro battery drain due to all the advanced micro circuits and such.

A good tender on such will keep it topped off, so to speak.

It’s the “up / down” storage charge factors that are very hard on their batteries.

My 2020 Challenger Scat Pack is stored in a drywall insulated garage, which is house attached.

It’s on a Deltran 1.25 amp tender for the winter.

Battery Tender Plus 12V Battery Charger and Maintainer: 1.25 AMP Powersport Battery Charger and Maintainer for Motorcycles, ATVs, UTVs - Smart 12 Volt Automatic Float Charger - 021-0128 https://a.co/d/ec44JJn

Same I use, never an issue

Disconnect the battery and you have no drain.

On many late model vehicles doing a battery disconnect can be way more complicated.

Deltran 1.25 amp battery tender is good. That being said if you put the car away with a fully charged battery (12.7 volts with no loads) it should be fine for several months if there is no draw on it.

I work in the commercial and industrial uninterruptible power supply industry.

We use a lot of batteries. Some things to consider based on my observations and talking solely about lead acid type batteries.

If the batteries go 6 months or more between charges the likelihood of thermal runaway increases. Thermal runaway is when the battery overheats under use (charge or discharge) to the point it goes up in flames. That said, does it happen all the time? Nope. But if it happens you know the customer is going to blame us and potentially cost the company millions of dollars in damages.

The device we use to maintain and charge these batteries costs way more than anything you are going to use, even our cheapest model. They are as scienced out as possible and are continuously monitored and updated to prevent issues, see the millions of dollars mentioned.

We recommend 5 year replacement intervals for the VRLA batteries, similar to a maintenance free, and 20 years for flooded cells, similar to old school add water type batteries. Now these are in climate controlled environments using state of the art technology with regular testing and maintenance. Something you in your garage cannot match.

With all of this there is still the, very, occasional issue with thermal runaway. So, I would never leave my battery on any kind of continual charge, especially unmonitored and unobserved.

I would go thru whatever monkeyshines I needed to unhook my fully charged battery during storage. I would attach a charger when I came back to prep it for the driving season and disconnect when I left, if I were the type to store a car for the season. I real life, I just drive them.

But what I never do is leave them on a charger and walk away.

Basic problem with the Battery Tender products is that they don't have a current/thermal shutoff...
So if something is shorted the Battery Tender should shut down, rather than continuing outputting a voltage and eventually overheating/shorting out..
In my personal case, I caught it early enough before it started a fire.
The product is built in China and its basic design should be modified to include a current/thermal shutoff..
But then its price would likely double..

Just my $0.02...

Incredible.....
I just got this notice from Hagerty...
"All it takes is a battery to get overcharged, or a wire to get rubbed a few too many times and cause an arc and suddenly there’s fire. It often happens silently and causes damage quickly.
Check your chargers or tender regularly to see if they are warm to the touch or otherwise defective. If possible, unplug them when not needed as it will minimize the risk of something melting down without you being there to catch it."

Just my $0.02...

It is a risk versus reward.

Reward is a few more months of battery and risk is multi thousand $ fire or death.

In the fine print of the insurance policies have they slipped in “no battery tender” wording?

My hot rod runs a walmart battery gussied up with some decals and fake red caps.

I just disconnect it and remove it from the car and set it in the warm basement for the 3 or 4 months of winter. So far no issues.

I used to run a battery tender but I've decided the (very small but potentially catastrophic) risk is not worth the marginal benefits on a cheap-o battery.

Yeah, cause that is the difference. Ask Rhino if insurance made him completely whole. That it replaced all the personal stuff that mean nothing to insurance policies but everything to you. Did it recompense him for all the aggravation and time he spent dealing with it and, God forbid, had a loved one died what price could you ever put on that?

CTEK

CTEK - 40-206 MXS 5.0 Fully Automatic 4.3 amp Battery Charger and Maintainer 12V

I used a battery tender on my race car for years when its home in the trailer but last year the green light was on indicating good when in fact the battery was bad and had to be replaced . I don't use the tender much anymore maybe on my winch battery once in awhile.

I use a CTEK MUS 4.3 POLAR battery charger/maintainer. Works great, no issues at all.

https://smartercharger.com/products/ctek-mus-4-3-polar

The battery charger/maintainer sold by Mopar Parts is manufactured by CTEK.

https://store.mopar.com/oem-parts/mopar-battery-charger-82213378ab

the charger i am using now is one of those pulse types that is supposed to do ????????
anyway, i just hook it up and charge away when i'm in the garage.
then, to make sure i unplug it when i go in the house, i have it hooked to a bright orange 14ga outside extension cord that is plugged into an outlet that is next to the door into the house. i can't miss that, so that works for me.

What about the battery chargers for tools? Are they safe to leave plugged in?

Probably not.

My fire was due to a 19.2V Sears cordless drill battery. I had one in the charger fully charged and put the dead battery in the charger when I found out it was completely dead. It only took 5 minutes to catch the garage on fire beyond any chance of putting it out. Apparently the dead battery had a dead short in it and the charger thought it was charging the battery, instead in got hot real fast and ignited papers and old broadcast sheets I had sitting next to the charger. I had it plugged into an old power strip straight into an outlet that went right to the breaker box. I DO NOT leave a battery being charged without me being there to watch it, especially for the first few minutes I plug it in. The insurance company (State Farm) did me good. The only things I did not get reimbursed for was my used and NOS parts since I did not have receipts for them, which was a significant loss! However they did pay for every one of my tools, but I had to buy them first then give them the receipts. I also had a collection of factory brochures from the 40's to the 90's that was lost, they paid me $5K for them, who knows how much I had in them over the years. The nightmares and agrivation still goes on today, I will never get fully over it...

I found out the drill chargers STILL draw a current with no battery plugged in, ALL stay unplugged till I need them. Another thing, key fobs on cars that have the push button starters. IF they are hung up within 30-50 feet of car the battery in fob will die. Seems inside that 50 feet the fob and car ‘talk’ to each other continuously till battery dies. Never leave it in car

A ready to be discarded microwave might offer a lot protection as an enclosed charging station.

I got in a habit of keeping chargers unplugged many years ago and after so many stories I’m glad I did. I think one was warm one day without a battery in it is why I started doing that.

The key fob thing is interesting. The spare key to my wife’s car is kept in a cabinet probably 25 feet away from the garage spot. I use it when I take it out about once a week. Today the car flashed the low battery warning again, I thought I must be getting junk quality batteries. Maybe not. I’ll move it and see how the new battery does. At my last house the batteries went forever, we had a detached garage then. Thanks.

I have noticed that the newest power tool battery chargers have changed design
and moved the 120AV to DC low voltage “switching power supply” to the wall plug,
where it can be made more flame resistant cheaper because there is less material.

It also makes the larger Lithium battery holder where wet dirty human hands touch often free of 120V AC and lowers lethal shock risk.
Old design long wall cord that had 120 AC becomes lower DC voltage.

I am speculating their insurance companies made them make that redesign.

I don't see any real advantages here of wall/outlet mounted with those changes except maybe lower manufacturing costs.
Maybe better convection cooling of being on an elevated vertical surface rather than a flat surface?
I personally discount the concerns of wet/dirty/120V aspects.

Happy New Year Moparts , The US Coast Guard has the on FIRE and BURNING Vessel "Genius Star XI ", anchored 2 MILES off the shore from Anchorage Alaska filled with Dangerous and
Unstable Lithium-Ion Batteries . At least when that Flaming Vessel finally Sinks , it's 2 miles from Beautiful Dutch Harbor ! Genius Star XI has been Burning since Xmas Day !

My fearless New Year prediction:

Just like the “bad guys with tech smarts”
quickly figured out how to unlock the doors and start the car
by hacking into the computer BUS network
at a relatively easy spot like the headlight,
another bad guy will figure out how to
set the perfectly good Li batteries on fire with a BUS network command code.

I've been using a schumacher automatic with desulfator for years with no issues. Battery always out of car and cord plugged into gfci and isolated far away from flammables and battery sitting on concrete in open spot. Batteries are roatated as they peak out and sometimes charger is unpludded when everything is topped off. I check with load tester once a month or so and top off when under 12.v static and 10v under load.
Battery tenders are not regularly used and relegated to small out buildings housing tractors and lawn equipment.
Rechargable tools, name brand and only plugged in using the NON rapid charge charger only when I am home.
Fire alarms in all sructures repote buildings mounted near eave vents.
Most important. Anytime I'm away they are all unplugged.

North Vietnam origin Lithium batteries, says AP, and that CO2 gas flooding of the affected cargo compartment did not stop the fire.
Previous reports say that at a certain temperature Li batteries “generate their own oxygen.”

https://www.aol.com/news/cargo-ship-carrying-burning-lithium-202847562.html