I used to pull the motorcycle battery in November, and leave it hooked up to a battery tender until early April-ish timeframe. The battery lasted 6 years; twice as long as my truck battery.

I'd agree with everyone else that chimed in on the smart battery tenders.

quote:

Can I leave a trickle charger hooked to a car for 2 weeks unattended?

Properly done with the proper equipment, yes, of course. Lead acid batteries are left on chargers for years at a time with no ill effects. Swing by one of your local telephone company central offices and check it out.

The very first answer to this post (and several others) is the correct answer. You have to know whether your particular charger is self regulating or continuous charge. They are not all the same. If it is self regulating you can leave it hooked up and charging for long periods of time. Otherwise, no. Checking the owner's manual or looking the charger info up on line by the model number would be how you find out if you don't know.

With a proper charger. One that knows how to ramp down to a maintenance charge when the battery's topped-off.

When we had two boats, 30' sailboat and 18' powerboat, I had three batteries to keep maintained through wintertime. I'd remove them from the boats, top each of them off separately, hook them in parallel and attach the trickle charger to keep them topped-off.

Worked fine.

quote:

Originally posted by 46and2:
Probably, but I wouldn't.

Is there really a battery that is so sensitive that it can't take 2wks of sitting?

Yes, older daughter got in trouble and has an intoxalock installed, it drains the battery in a couple of days.

I am mostly worried about fire danger.
Self regulating seems the best way to go.

quote:

Originally posted by lbj:

quote:

Originally posted by 46and2:
Probably, but I wouldn't.

Is there really a battery that is so sensitive that it can't take 2wks of sitting?

Yes, older daughter got in trouble and has an intoxalock installed, it drains the battery in a couple of days.

I am mostly worried about fire danger.
Self regulating seems the best way to go.

Self-regulating or just disconnect the neg. cable while you're gone and reconnect when you return.

quote:

Originally posted by lbj:
Yes, older daughter got in trouble and has an intoxalock installed, it drains the battery in a couple of days.

Ah. Well, problem. That drain may well muck with the charger's smarts and cause it to cook the battery. Dunno.

quote:

Originally posted by comet24:
...just disconnect the neg. cable while you're gone and reconnect when you return.

I don't think this will work well on modern vehicles -- those with onboard memories, like the radio/sound system, anti-theft systems, and maybe the engine computers as well. If they die it isn't always something that can just be turned on again, they will require reprogramming.

quote:

Originally posted by lbj:
Yes, older daughter got in trouble and has an intoxalock installed, it drains the battery in a couple of days...

Is it her car we're talking about? If so, I'd check with the manufacturer of the intoxalock before doing anything.

So here's the deal with battery chargers and maintainers. As a preface, batteries do not have a charge level indicator like a gas tank has. There is no "full" level. But the voltage of a battery will change as it charges discharges. For example, a "12 volt" car battery may be at 11.9 volts or 14.4 volts. So chargers and maintainers that are "smart" will monitor the voltage of the battery, and when that voltage reaches the high end of acceptable, it assumes the battery is "full".

Batteries will have some natural discharge rate, even when not hooked up to something. That rate is generally pretty low. When hooked up to something, such as an automobile, the discharge rate will be the natural discharge rate, plus whatever current draw is being used by the vehicle. Either way, there is a certain amount of battery being drained.

Most chargers these days are what people call a "smart charger". They will charge at whatever rate, say 1 amp, 3 amps, 5 amps, 10 amps, etc., until the voltage reaches a certain level. Then they switch to "maintenance mode", and charge at .1 amp (100 milliamps) or something of that nature. These are fine for most applications, as the vehicle has a discharge rate that exceeds that "maintenance mode" level of charging. So eventually the battery will drop below the set voltage level and will kick on, charging at a higher rate until the voltage reaches the higher level, and then it will switch back to maintenance mode.

What you may not realize is that even most "smart chargers" keep charging, although at a lower rate, once they detect that the battery is fully charged. If the battery is small, like a motorcycle or lawn mower battery, even this maintenance level of charge may exceed the discharge rate of the battery, and with enough time it will cook it and ruin it. Especially if it's a small battery and not hooked up to anything with additional draw.

There are a few, but still very few, chargers that are not only "smart", but practically "genius". They're so smart that when the battery reaches a certain voltage, they stop charging altogether, until the voltage drops below a certain level.

Here is a link to one brand of "Genius" battery chargers:

https://no.co/products/charging/multipurpose

The manufacturer of the intoxalock recommends a trickle charger when the car s not in use for weeks at a time.

I think I will use a self regulating trickle charge and have in on a timer for 12 hours a day.

Thoughts?

Honestlou is correct with his statement.

I prefer the Deltran Battery Tender, you can get them at most motorcycle shops, I sell them at a Harley Davidson dealership for about 40 dollars.

I use them on the bikes, the one collector car that is driveable and the lawn tractor.

The timer would be ok. I just plug mine in and let them go. THe battery in my '02 Electra Glide is five years old, the car's battery is a WalMart Johnson Control top of the line and is seven years old.

My JD X Series, when I got it my S-I-L, a Deere trained tech said it would last one season, maybe two if lucky. Bought it March '10, battery lasted until the end of mowing season of '15.

Your results may vary, I have to say that.

Is this the Deltran you all are posting about?

http://www.autozone.com/test-s...y-charger/756181_0_0

I have one like that and a Battery Tender Plus, for my diesel tractor. The "Plus" has a higher maximum charge rate, I believe.

quote:

Originally posted by lbj:
Is this the Deltran you all are posting about?

http://www.autozone.com/test-s...y-charger/756181_0_0

No. That's the Deltran Battery Tender Junior. The difference is that it "Automatically switches to float / maintenance voltage after fully charging the battery." The 'maintenance voltage' is not as good as a pure float voltage. I had a boat battery go bad quickly on this model of Deltran, and then learned that it is inferior to the Deltran Battery Tender Plus.

The Deltran Battery Tender Plus is a true smart charger with a pure float voltage stage. It "Automatically switches from full charge to float charging mode." It's a bit more expensive but I've had motorcycle batteries last six years on them.

It may sound like no difference but I won't have the "Junior" model again.

quote:

Originally posted by FRANKT:

quote:

Can I leave a trickle charger hooked to a car for 2 weeks unattended?

Properly done with the proper equipment, yes, of course. Lead acid batteries are left on chargers for years at a time with no ill effects. Swing by one of your local telephone company central offices and check it out.

These have a regulator and to my knowledge, the battery tender does not.

The Central Office battery backup has maintenance preformed from time to time.

The model Deltran Battery Tender I is the Plus; 12V 1.2a.
http://products.batterytender....ry-TenderR-Plus.html

The one you linked, different feature; 12V 750mA
http://products.batterytender....unior-12V-0-75A.html

quote:

Originally posted by 46and2:
Probably, but I wouldn't.

Is there really a battery that is so sensitive that it can't take 2wks of sitting?

This.

 
We have used the Deltran Battery Tender Plus on several "vehicles" for over 10 years. My wife's Sequoia, which gets driven once a month, my Kubota tractor, which gets out once every few months. The chargers are always on, and have the electronics to monitor the charge and adapt the charge. Best thing we ever used.
 

quote:

Originally posted by arfmel:
A "battery tender" brand battery maintainer won't hurt anything. I leave a vehicle on one for months at a stretch.

I do as well and would recommend that for lbj.