trickle chargers?

I should be using trickle chargers (couple 6 volt and several 12 volt); what are pluses and minuses and what units and sources are recommended? Herb(GA)

Yea, I bought a small one that cost maybe $20. It puts out about 1 amp. Has a red and green  LED light on the outside. Connnect up the clamps and let it set for months.. Charges slowly on red, when its charge it goes to green... will set for a few days, then back to red... holds voltage VERY CONSTANT........ about the size of a pack of cigaretts.

I've found that some are better than others, but in most cases, I feel most comfortable using an ordinary motorcycle battery charger (1A) on a mechanical timer, that's on a mechanical timer... here's how I do it:

I have several battery chargers, connected to several battery chargers.  The batteries are from my boats, for my generators, and for my motorcycles.  The chargers are all fed from a power strip.

Powering this power strip is a mechanical timer, set to run for fifteen minutes in a full day's revolution.  This timer is powered by a second timer, which is set to run for eight hours a day.

Combine them, and you'll find that the mechanical timer only advances eight hours each day... so the other timer takes three days to make it's circle.  That's fifteen minutes every three days... which is more than sufficient to 'hold' any battery.

Why do it this way?

Well, because I found that many of my trickle chargers, in operation, weren't any better than, and oftentimes worse than running no charger at all.  When the 'charged' light is on, it's discharging the battery.  While that happens, there's a resistor bridge and measurement circuitry drawing current to run the charger's logic...  so the charger is generally charging what it's discharged.  In the event of a failed charger, that little light, and the voltage sensing circuitry depletes the battery, and when you finally figure it out, the battery has been dead flat, and frozen... for a month or more.

By running the chargers the way I do, the only discharging is what occurs internal to the battery, which isn't much.  Fifteen minutes every three days is ample, and with the two timers in series, I can dial that up or down any way I see necessary.  It's crude, but incredibly effective.

Compare the prices of a trickle charger and a 6 AMP "smart" charger. The smart charger would be more versatile. If you can find one for $20 more, I'd go with the smart charger.

I know there are fans of trickle chargers but I am not one of them.

Leaving some electrical device (charger) plugged in to another electrical device (battery) all winter long in an out building or garage that I don't check on everyday is too much risk for a fire or other issue for me.


I have those turn knob style battery disconnects on my older stuff. When not going to be used for awhile make sure the battery is fully charged, unscrew the disconnect and the battery should still be fully charged when needed as there was no electrical circuit to drain the battery. The battery in my '59 Chevy is going on 12 years old (knock on wood) and some others are at 7+.

Never figured out why you need to "maintain" a battery with a trickle charger, if you disconnect it and it is fully charged there is no reason for it to lose it's charge. Sure I have to reset the clock on 2 of the cars but not a big deal, and I know someone for some reason needs the battery connected ALL the time but I don't on any of my stuff.

Edited by iowallis - 29 Sep 2018 at 8:48am

DMiller's post is why I mentioned smart chargers. A good one won't overcharge. It should switch to the "float" mode once the battery is charged. At float the charger applies about 13.3 volts, which keeps the battery charged while not boiling the battery. Even a 1 AMP charger can boil a battery if it is applying too high of a voltage.

Has anyone had experience with the ones you can get from Harbor Freight at $5 a pop when they are one sale or with a coupon?  They are only for 12 volt, but I've put them on my 4 wheelers and a vehicle not used much over the winter and they seem to do their job.  Dave

I have a couple solar charger in my building and move the m around to different batteries all year round

Edited by jaybmiller - 30 Sep 2018 at 7:52am

Look at one similar to this:

https://www.batterystuff.com/battery-chargers/battery-tender-6v-12v-battery-tender-plus-high-efficiency-charger-022-0211-dl-wh.html

It's a bit more pricy than the $5 ones some have mentioned and it's Made in Asia, but you'll pay an arm and a leg for more charger. Note that this one does 6 and 12 volts.

https://www.ebay.com/itm/Deltran-Battery-Tender-Junior-Jr-12V-Battery-Maintainer-Charger-New-021-0123/331960260648?epid=1411813777&hash=item4d4a5f9828

When overcharged at battery does NOT boil. It just looks like its boiling because the overcharge energy is causing the water to dissociate into elemental oxygen and hydrogen with the perfect ratio (two parts hydrogen gas to one part oxygen gas) for the biggest bang if ignited. And those gases are fairly easy to ignite. The gases bubble in the electrolyte and that does look like it is boiling but it isn't nearly hot enough to boil.

Gerald J.

When I look at some of the links for battery maintainers listed here, I find the price is close to, and sometimes more than, a smart charger.

I would not trust my $125.00 battery to a $20.00 charger/maintainer/whatever until I've monitored the voltage every hour for the first two days with a very accurate digital voltmeter. If the voltage remains at 13.6 or higher after a couple of days, the battery is eventually going to cook. Halve that voltage number if you are dealing with a 6 volt battery.