Harbor Freight Battery Float Charger

[SDSeville]

Has anyone tried one of these Harbor Freight battery chargers? Seems like a cheap way to keep your battery topped off.

http://www.harborfreight.com/automat...ger-42292.html

[denL]

I bought one a few months ago and it seems to keep my Walmart Battery charged up.

[SDSeville]

I am just worried about over charging. It says it turns off automatically.

[Reel Kahuna]

The one I bought boiled my mc battery

[smokingcrater]

I am just worried about over charging. It says it turns off automatically.

I don't trust ANY charger connected to a battery continously. Put it on a timer so it only runs an hour or so a day.

[bassman284]

I don't trust ANY charger connected to a battery continously. Put it on a timer so it only runs an hour or so a day.

Me too. I've been on this forum for several years an have avoided the trickle charge/float charge debate but IMO they're a scam. Junk. DO NOT USE!!!. Get a decent 10 amp automatic charger and put it on your battery after a day's use and hook it up every month or two during periods of non use. You will probably find it doesn't drop off much. A continuous charge WILL cook your battery.

If you download the product manual on this one the first thing it says is don't use on deep cycle or AGM batteries. Also never tells you the output of the charger. I guess if you've got 10 bucks you don't need and a battery you really hate, this is the deal for you.

[Mi duckdown]

waste of money. batterys don't go bad sitting there unless you have a drain. or your billge pump is runnning alot.
at that point you have a leak.

[df909]

Harbor Freight is cheapo low end too. If you on'y want to use it once and don't care if it breaks the second time you try to use it, then get it at Harbor Freight.

[Marfark]

I have a similar one that I bought at Northern Tool for about ten bucks. I keep it connected to my car's battery and my motorcycle battery (with two jumper wires) for six months at a stretch while I'm working in Afghanistan. It works great. The batteries are fresh and ready to use. The only problem I've had was when my genius roommate turned off power to the garage. The trickle charger became a trickle drainer, and it destroyed my car's battery (the motorcycle battery wasn't connected that time).

I've checked the voltage while it's charging. It puts out 12.9 volts, which is about .1 volt over a fully charged battery, and about .6 volts lower than a typical alternator output. I've heard people say it will overcharge or boil a battery or something like that, but I don't buy it. Lots of over-the-road trucks with team drivers are on the move almost nonstop for weeks at a time, only stopping for fuel and food, all the while charging their batteries at 13.5-14 volts. It's not an issue.

[boaterinsd]

its not the going bad , but the normal discharge over time that it prevents. If it is discharged to the point and the battery gets cold enough it will freeze. A fully charged battery wont freeze. My Sears charger works wonderfully. No problems, i even have it rotating on the 2 boat and the RV camper battery I remove for its winter storage.

[JoLin]

Lots of over-the-road trucks with team drivers are on the move almost nonstop for weeks at a time, only stopping for fuel and food, all the while charging their batteries at 13.5-14 volts. It's not an issue.

The alternators on cars and trucks don't continuously charge the batteries. They're equipped with voltage regulators that cycle the charge on and off as needed. If the regulator fails the battery will either discharge or overcharge and be ruined in short order.

At the end of last October I filled, desulfated and charged the 2 wet-cell batteries on my Chris*Craft. I disconnected the battery cables and left the batts in place. Didn't touch them again all Winter. Yesterday I put the charger on the first and within 5 minutes the charger beeped and the diplay showed it was charged. The other batt took about 45 minutes, but the charge rate peaked at only 2.5 amps. Good batteries, fully charged, don't lose much even over several months of sub-freezing temperatures.

I wouldn't trust a trickle charger kept plugged in all the time.

My .02

[SDSeville]

Bassman was right. The manual says "Not recommended for deep-cycle batteries." Oh well... it was on sale for $5. Sounded too good to be true anyway.

[Boatist]

Just a little information about batteries and battery charging.

First all lead acid batteries self discharge.
Like most chemical reactions they discharge faster as the temperatures goes up.
A lead acid battery cell is 2.1 volts per cell and with 6 cells that is 12.6 volts.

Car and Truck Alternators do charge the entire time the engine is running.
The Voltage regulator will control the voltage output from 13.8 volts to as high as 15 volts. Some newer voltage regulators change voltage as the temperature changes.
The voltage regulator in my truck when the air is cold will be between 14.8 and 15 volts.
When everything is hot it will be between 13.8 volts and 14.0 volts.

Harbor Freight chargers. The low price Float Charges is very low amperage and battery voltage will stay at 13.2 volts. If you put it on a timer when the timer shuts off the red light stays on. While it is likely only a 20 milli amp drain it does come from the battery.

The 1.5 amp automatic charger voltage output will stay at 13.48 volts when the Yellow charging lights goes out. The Green light stays on if it is plugged into the ac outlet or connected to the battery. Again with power coming from the battery.

I do not believe either of these harbor freight battery chargers will damage the battery if left on charge the whole time. However I do not think it is necessary to charge a battery full time.
However the industry I work in (Computer Industry) charges the batteries full time. You can bet the server that runs this site and all important computers everywhere is running off a battery backup system that is charged 24 hours a day year after year.
They swap the batteries out about every 5 years before failure.

Unlike the regulated chargers above most trickle chargers do not control the voltage at all and after a couple of day battery voltage may be 18 to 20 volts and that is not good for your batteries.

[j_martin]

I have a couple of good battery maintainers. They switch on at about 12.4V, and switch off somewhere around 14.2. I tried the harbor freight ones, and one boiled the battery over the winter, one was dead flat and shot come spring, and 3 others worked fine. Odds aren't good enough to use that cheap junk any more.

Good ones cost between 20 and 75 bucks.

[John_S]

I don't advocate any trickle charger, or leaving any charger on continuous, but ones like HF, don't detect other fault conditions. If there is a problem with battery (such as bad cell) it just going to keep trying to charge regardless of amout of time. Just the dead batteris mentioned in this thread, related to trickle chargers, should be enough to keep away.