Trickle-charger question....

[Dottore]

I have a couple of newish cars to store for 4 or 5 months. The place I want to store them has no electrical outlet, though I could run an extension cable in through a window.

Is there any fire risk in hooking up a trickle charger (unsupervised) for this length of time?

Should I take out the batteries to reduce risk?

Would just unplugging the leads (without trickle-charger) keep them alive for this length of time?

Any thoughts?

[Rick V]

A battery tender is designed to maintain a proper charge for extended periods of time, unlike a regular charger (even at a low rate) I would look into something like that for your needs. I have a 1/4 amp tender I use on my 911 when she goes to sleep for the winter and have had no issues.

[Dottore]

Originally Posted by Rick V

A battery tender is designed to maintain a proper charge for extended periods of time, unlike a regular charger (even at a low rate) I would look into something like that for your needs. I have a 1/4 amp tender I use on my 911 when she goes to sleep for the winter and have had no issues.

Would you have no hesitation in leaving a battery tender in place unattended for a period of several months? I just ask because it seems to me there could be a fire hazard.

[Seahawk]

Originally Posted by Dottore

Would you have no hesitation in leaving a battery tender in place unattended for a period of several months? I just ask because it seems to me there could be a fire hazard.

I use tenders for my farm equipment during the winter for months at a time, never had an issue.

Deltran Battery Tender, Brand Battery Chargers & Tenders, battery tender jr, battery tender plus

[widgeon13]

I was in a guys hangar the other day and he has 4 battery tenders hooked up to snowmobiles. Leaves them on all the time. If his places goes, so does mine.

[s_morrison57]

I worry about fire too and don't leave my tender on when I'm out of town, your probably safe but I worry about that kinda stuff so I just unhook the battery. Leave the tanks full of fuel and maybe a fuel conditioner might be an idea for that length of time.
Finn

[jcommin]

I use a trickle charger from Nov 1 to March 1 with no problem. I use the 12v outlet inside the car.

The other option is to take the battery out and store it inside using the charger.

[GH85Carrera]

I use a batery tender in the winter months. You want to use a smart charger not just a trickle charger. Mine never sits for more than two months max.

On many of the new cars the last thing you want to do is disconnect the battery. A new 997 will not even run if you disconnect and then reconnect the battery. You will be calling for a tow truck.

[wdfifteen]

Originally Posted by Dottore

I have a couple of newish cars to store for 4 or 5 months. The place I want to store them has no electrical outlet, though I could run an extension cable in through a window.

Is there any fire risk in hooking up a trickle charger (unsupervised) for this length of time?

Should I take out the batteries to reduce risk?

Would just unplugging the leads (without trickle-charger) keep them alive for this length of time?

Any thoughts?

For a period of a few months I remove the batteries, store them somewhere away from the cars, and connect them to a battery tender. It's safer and gives me an opportunity to clean the battery area in the car with bi-carb and clean the terminals.

[David]

I leave Battery Tenders on my 930 and motorcycles all the time and have no concern about fire.

There's some cathodic protection for a vehicle with a negative ground so there's a reason to leave the battery in the car and connected.

[VINMAN]

I leave a battery tender on my wave runner yr round. Never a thought not to.

[1990C4S]

Where would you expect a fire to start? At the battery? That's unlikely as there is no source of ignition.

The charging device itself might catch fire, but I think that is very unlikely.

I use a cheap $10 charger (not a chipped trickle charger) on a 'outlet timer' all winter. One hour per day. I keep the charger on the cement floor (not under the hood).

The reality is if you use a decent quality extension cord a decent charger (probably shouldn't use HF) then you should have no reason to lose sleep.

On the other hand an acquaintance of mine lost his entire house due to a 'dollar store' power bar catching fire in the night.

[Por_sha911]

Most newer cars have a memory in their ECU so do not disconnect the battery without checking the proper reference manual for each vehicle.
Get a low low amperage float (or smart) charger. It will cycle on and off at certain battery levels. Some "trickle" chargers are just love amp chargers that send a small current of power all the time. As others have said, for peace of mind, avoid the HF unit. Lots of info here: Battery Tender - Home of the Battery Tender Jr. - Batterytender.com
Setup the charger with the ring connections directly to the battery terminals (as opposed to the alligator clips) for a better connection.
If you're wanting to be uber safe, you can connect the charger to a GFCI wall outlet.

[Hugh R]

If you take the batteries out, store them on a piece of wood. The cold concrete will hasten their discharge.

[rick-l]

The V-I curbe of a trickle charger is shown below. I'm not real sure what is going to catch on fire. A GFCI will only protect you if you break the cover off the wall wart transformer and poke around in there.

Originally Posted by rick-l

harborfreight.com Itemnumber=42292

I went into harbor freight and they had these for $3.93 with the coupon that was by the front door. They easily had 500 of them sitting there.

It looks like the 7805 and R1, R2 and R_VR1 sets the output voltage to 13.75.
The charge current is set by R5 D1, D2( a generic LED not the one listed in the spice model) and the beta of Q1 which is a TIP41C.
Q2 (an S9013), R3 and R4 shut down the output isf the battery is below about 9 volts.

The plot is the current into the battery versus battery voltage.

It looks like if you have it attached to the battery and not plugged in it will draw about 50 mAmps, however you could change that by adding a diode and adjusting the resistors around the 7805.