Automatic Battery Float Charger

Comments about Cen-Tech Automatic Battery Float Charger:

used on my tractor battery that was barely strong enough to turn it over. it was a good battery just was weak from sitting over winter. i left it on the float charger for a week and its back up to its normal charge.

Comments about Cen-Tech Automatic Battery Float Charger:

Bought two of these for my two motorcycles.... 2 weeks later (should have check sooner) went out to two completely dead batteries. Charged the batteries and tried again with these floats, thinking maybe I did something wrong, but nope, batteries steadily lost charge. As much as batteries cost, do yourself a favor and buy something you know will work.

Comments about Cen-Tech Automatic Battery Float Charger:

These chargers are FLOAT chargers. They are NOT designed to charge batteries from a discharged state. (These chargers are capable of only 1/2 amp at 14+ volts.) They are designed to maintain a fully CHARGED battery in its fully charged or current state, not charge a discharged battery. They do this by monitoring the battery voltage via the circuitry in the little square box in the charge line, and providing a charging voltage just a little bit higher, 0.2 to 0.6 volts, than the at-rest voltage. A fully charged lead-acid battery has a voltage around 12.9 volts, and is "fully discharged" at around 11.4 volts. (These values are based on the specific gravity of the battery acid and vary depending on the chemistry of the battery, i.e, flooded, gel, glass mat, sealed, etc.) Below 11 volts, this charger should not do anything other than possibly discharge the battery. Reading all the comments, the chargers worked properly. They did the job they're supposed to, MAINTAIN the charge in a battery, although they could probably use some circuity to prevent totally discharging the battery. One user actually turned the float charger into a regular charger by inserting a diode into one of the lines. This effecively disables the circuitry in the little control box and allows the charger to apply its full voltage, around 14+ to the ends of the cables instead of the maximum 13.2 volts when the control circuit is working. The diode prevents it from discharging the battery, but also disables the "float" feature, and can overcharge the battery. Basically, the chargers were working as advertised.

Comments about Cen-Tech Automatic Battery Float Charger:

I was looking for a battery maintainer for my weekend car, which goes untouched for weeks at a time. After all the stories about dead batteries, I thought this would be a good cheap solution.

I hooked it up and let it charge. During charging, the power adapter get pretty hot. Once the battery is fully charged, it cools down.

I was happy with this unit until I decided to check the floating voltage. To my surprise, it showed 14.5 volts. I returned the unit since the manual says maximum output of 13.2 VDC. The second unit I got, it showed 14.4. I exchanged it again and the final voltage was 14.1 VDC.

I kept the last unit but I only plug it in for about 12 hours every other week now.

I am giving it 1 star because after 3 units, I did not get one within specs. I cant use the device as intended and be confident it will not kill my battery.

If you disagree with this post, please post your final voltage.

Comments about Cen-Tech Automatic Battery Float Charger:

These destroyed EVERY battery, regardless of standard, deep cycle (flooded or mats), and amperage. Inconsistent output from <9VDC to 17VDC.
Exchanged failed units with same results. These are a trash product that has cost me HUNDREDS in ruined batteries and a good deal of time. HF should be ashamed to continue to sell these products

Comments about Cen-Tech Automatic Battery Float Charger:

seems to work fine, but the light is always red so you never know if the battery is charged or not. Most charger's LED turns green so you know it is fully charged.

Comments about Cen-Tech Automatic Battery Float Charger:

I bought two of these to keep my tractor batteries charged up during the winter. I keep one on the tractor with the snow plow and that baby fires right up in 15 degree weather! Very Pleased with this product.

Comments about Cen-Tech Automatic Battery Float Charger:

The issue of battery drainage can be cured by installing a pair of diodes on the output wires. I used 6A - 50V diodes because I had them on hand (normally about $3). They need to be soldered in the wires before the clamps and well insulated. Just slide a length of tubing over the wires before soldering the diodes on, then seal the ends of the tubing with silicone to keep water out.

Comments about Cen-Tech Automatic Battery Float Charger:

After checking my battery (11.0 volts), I attached the charger per instructions. Checked back 24 hours later to find battery at only 11.1 volts- not good. Then checked the output of charger to find it at .o95 amps. Believing the unit to be defective, I exchanged it for another one. The second one showed .101 amps output. Unless I got the only 2 bad units in existence, I have to conclude that this unit is too weak to be useful as a charger or as a maintainer. Thankfully Harbor Freight refunded the price, and I bought another brand name charger which performed as advertised. My advice is to avoid this charger. You need a charger capable of at least 1.5 amps to be effective. Most output 2 amp or more.

Comments about Cen-Tech Automatic Battery Float Charger:

Several people have noted that it draws current from the battery if not plugged in. That's a fact, and it could drain your battery to zero if you leave it connected but unplugged, and you don't realize it for a long time.

On the other hand, mine produces open-circuit voltage (carefully checked with high-quality instruments) of 14.16 volts. That's much too high for typical storage batteries, which should float at 13.2 volts. If used (plugged in) for a long time, it could overcharge and ruin a battery. Of course, they might all be set differently, but there's no way to adjust the voltage once it's sealed.

Mine's going right into the trash. If you must use one, check the battery voltage frequently with a high-quality digital voltmeter and don't let the battery voltage rise much above 13.2 volts. Don't just set-and-forget for the winter; you might get an unpleasant surprise in the spring.