Automatic "Trickle" Battery Chargers

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Automatic \"Trickle\" Battery Chargers

I'm looking to keep the 12V battery on my generator charged. I've seen small 1/2 amp trickle chargers advertised that are supposed to have an automatic feature - they charge the battery then shut off. The battery shop owner says they are very unreliable and overcharge the batteries 50% of the time. He even states they will start fires. Any prior experience or knowledge about these units?

 

[rdricks]

Re: Automatic \"Trickle\" Battery Chargers

I use a 12v Trickle charger for my trailer battery - 12v deep cycle. I haven't had any problems, but I also do not leave the charger connected all the time. During the camping season I charge it up a couple of days before we leave. During the winter I put the battery on the charger about once a month to "top it off" then disconnect.

 

[JerryG]

Re: Automatic \"Trickle\" Battery Chargers

I have a trickle charger on my 166 hp 100 kw generator. I have had good luck with it. I recommend them to everyone with a generator especially automatic standby generators.

 

[Wingnut]

Re: Automatic \"Trickle\" Battery Chargers

I have 3 different 1/2A "automatic" trickle chargers. I use them for the little batteries that don't get used enough for them to keep the batteries in good shape: the snowmobile, the atv and the lawn tractor. I switch them off at times to the generator and the motorcycle (season permitting).
Since I've been using them, I've replaced far fewer batteries. Never had an overheat problem with the batteries ... but I am using the "smart" chargers that sense current and cycle properly.
I don't worry about the generator too much as I try to follow the instructions of starting and running for 1/2 hour ... no longer weekly but I try to stick to bi-weekly. That keeps the battery charged enough.
(I tend to use it for outdoor power quite a bit ... that way it's not just running, it's being used)

 

[rocky2]

Re: Automatic \"Trickle\" Battery Chargers

My boat has a three phase onboard charger, heavy charge, medium and trickle/shutoff. It’s about the size of a cigar box and will maintain up to 3 batteries of all types, gell, maintenance free, regular cell. If they're regular batteries, just be sure to check the battery water levels every month or so. The boat is plugged in at a marina April thru October and both batteries stay fully charged all season, unless something happens like the dockside circuit breaker tripping. To contradict what the guy at the battery place said about fires and lunching out batteries, if that were the case every cruiser docked should be burning up or replacing batteries on a regular basis. And I know that’s not happening. I just replaced the charger this season and it cost a little over a hundred bucks. At home you can screw it on a wall, run your power to it, and run the "to battery" wires with alligator clips.

 

[Mike_Dumond]

Re: Automatic \"Trickle\" Battery Chargers

Chris,
A 1/2 amp or 1 amp trickle charger won't over charge your battery by any great amount. However, a better approach, (especially if the generator is an emergency power source), would be to run your generator for a half hour or so every month. Keeps the battery charged and lets you know the generator will be operational when you need it.

Of course, this is just my opinion. I could be wrong.

 

[GlennT]

Re: Automatic \"Trickle\" Battery Chargers

I had a couple of riding mowers for awhile and it seemed that the battery on one or the other was always down when I wanted to use it, so I purchased a couple of "Automatic Battery Float Chargers" from Harbor Freight. Supposedly this item "maintains a full charge with overcharging" and "includes automatic safety shut off." I've used these float chargers for approximately a year and a half and they seem to do what is claimed for them. They were about $8 each on sale. I have no idea if and how a "float charger" differs from a regular battery charger.

 

[TimSullivan]

Re: Automatic \"Trickle\" Battery Chargers

Yes!!

I lost a 1962 TVR in a fire caused by a trickle charger. The car was stored in an old garage behind our home and the charger was set up to keep the battery charged.

The insurance company found that the battery was over charged and feed current back to the charger and started it on fire. Saved the garage but the car was a loss.

I still use a trickle charger in the winter but do not leave it on all the time.

 

[patrickg]

Re: Automatic

I have three of the little buggers and as they began to proliferate around here, I extended the wires with ring terminals that went to the batt and put a small set of batt clamps on so I could easily swap that one charger from batt to batt. Next I think I will install a polarized socket on each vehicle/thingy I want to charge so I can just plug the charger in at an acessiblel location and not have to raise the hood or climb under my dune buggy. Mine cost about $30 and are designed for permanent installation into a vehicle (poo to that!).

I have one on my mom's deep cycle battery for emergency lighting and power for her safe room. So far I have been pleased with these units (Shrader).

Someone asked what could go wrong with this sort of item. I won't attempt to address all the failure modes but I will describe a way for a unit to be designed/implemented incorrectly. First, let me say that charging a lead acid batt can cause it to outgas via electrolysis (consuming water from the electrolyte). This is especially true when the batt voltage is high and charging current continues.

Often in a batt charger, a regular step down transformer like you might use in a power supply has rectifier(s) in its output to make pulsating DC to charge the batt. The RMS voltage of the waveform might be equal to the float value selected, say 14.2 volts. If the RMS is 14.2 volts then the peak is about 20 volts. During that part of the alternation when the output is between 14.2 and 20 volts the battery continues to charge some. This sort of circuit won't stop charging until the batt reached 20 volts and as that won't happen the batt gets overcharged and in the process gets "boiled dry" (actually looses electrolyte through electrolysis). A smarter circuit uses a SCR, triac, or whatever to turn the current off when the batt reaches the set value. Usually there is a little hysteresis designed in so the batt has to fall down a bit in voltaage before the ckt turns back on (like a low pressure turn on and high pressure turn off for a water well controller). Sometimes there is a LED that is on when charging and it will begin to blink rather than be on or off when the unit is cycling at the set point.

There are a lot of different ways to make one of these chargers that works without hurting your batt. As you employ a new one (a brand/type not familliar to you) monitor the electrolyte level and batt voltage frequently. If it doesn't overcharge voltage wise or cause the loss of electrolyte you can safely lengthen out the intervals between voltage/electrolyte checks. I would be happy to see the voltage level out at a value greater than 12.6 and would get nervous if this sort of charger got over 14 volts or so. I trust the units I am using, based on actual experience, to be safe to ignore for a few months at a time except maybe on the chipper batt (smallest one I have but havent used it there yet). Like others have said, I rotate one of the chargers between a couple three different vehicles depending on usage patterns.

Regarding the attached sketch: "A" is the positive alternation, "B" is the negative alternation, "B prime" is the rectified negative alternation. The dashed horizontal line is the DC voltage level equivalent to the rectified waveform compried of A and B prime. If the DC equivalent value shown by the dashed horizontal line (AKA RMS-root mean square) is 14.2 volts then the peak value of the two positive pulses is nearly 20 volts. Difficult to see in the drawing since I scaled it to show that 10 volts RMS is about 14 volts peak. The ratio stays the same with a sine wave voltage. The peak value is 1.414 times the RMS value. Battery chargers usually do NOT have filtration and their outputs typically are NOT smooth DC. So, should you venture to Radio Shack to get parts to build your econo-charger be careful that you don't overcharge your battery and dry it out. This can be done over time even with a charger that is capable of less than 1/2 amp of current, provided that it isn't designed properly. the quick and dirty charging circuits are fine for temp use but should not be left connected indefinitely as they will ruin a batt.

Patrick

 

[Ozarker]

Re: Automatic

Use the <A target="_blank" HREF=http://www.batterystuff.com/battery/solar_chargers.htm#saver%20plus>sun.</A>

 

[tsh3]

Re: Automatic \"Trickle\" Battery Chargers

I have a friend that used a trickle charger on a Porsche that he did not drive much.
Battery exploded and acid went everywhere.

 

[heehaw]

Re: Automatic \"Trickle\" Battery Chargers

i picked up a cheap timer from the hardware store, plug the trickle charger into the timer and let it charge for 10-15 min every day...been doing it for several years with not problems.
heehaw

 

[Jeff396]

Re: Automatic

I do the same trick with my radio control planes. After using them I hook their chargers up to a lamp timer and set it for the number of hours I think necessary to completely re charge them. Then the lamp timer will come on for 1 hour every day after that to keep them ready to go.

I have a Battery Tender for my Vette and Kubota and one made by Excide for my Bird. I have been using them for close to a year now without any problems. This thread has me concerned that maybe that isn't such a good idea. It sure is nice , though, to go out to the garage and know that the car will turn over after a long period of sitting idle./w3tcompact/icons/smile.gif

Jeff

 

[hazmat]

Re: Automatic

I've been using one of these <A target="_blank" HREF=http://www.boatus-store.com/browse/item.asp?IID=30385> Guest Battery Charger </A> on my boat. I used it at the slip for a year. Now the boat is on a trailer in the driveway. The charger is nice because it has fast & slow charge. I can plug it in for an hour or two & top off the battery before heading to the launch ramp. In fact, this reminds me, its been awhile since I plugged it in, probably time to top it off. No problems overheating the battery.

You do get what you pay for $8 at Harbor freight vs $100+ for a marine unit. I know, I know, the fact that it is "marine" adds 50% to the price, but you get the point.

 

[Anonymous Poster]

Re: Automatic

Saw a 1 amp Exide charger today at a Big Lots Store. It cost $5.99. Nearly bought it for storing the tractor and lawn mower over winter but I had some concerns. The timer idea sounds good. I think I will get both and try that.

 

[DUMBDOG]

Re: Automatic \"Trickle\" Battery Chargers

Check out the Harley-Davidson catalog. They had one that worked really well with a five year warranty. The big drawback was the price. goes with the name, i believe it was about $50.

 

[Anonymous Poster]

Re: Automatic

This is what you need:

<A target="_blank" HREF=http://www.probike.co.uk/im050004.htm>http://www.probike.co.uk/im050004.htm</A>. This is probably what Harley is selling out of their catalog. I think the parent company is Motion Pro, but the chargers are called batterymate. I use their larger versions ($500) for my shop and they seem to make a good product. The little charger (Optimate 3) shuts itself off when it senses 12.6 volts and turns itself on again when the voltage drops. It also can sense sulfated batteries and somehow apply enough voltage to restore sulfated plates (they claim). I dont know what the little one costs, but I bet it is a good product. My mechanics have been abusing my big chargers for years, and they seem to take it without any fires. Knock on wood. /w3tcompact/icons/hmm.gif

 

[Anonymous Poster]

Re: Automatic

whoops. That link was to a U.K. website. Here is a better one.

<A target="_blank" HREF=http://www.motionpro.com/>http://www.motionpro.com/</A> Also, it looks like the parent company is Tecmate not Motion Pro. You get the idea anyway. /w3tcompact/icons/smile.gif

 

[GlennT]

Re: Automatic

Hazmat--I agree about "getting what you pay for." I perhaps should have added that I remove the battery from the mower (which also gives me an opportunity to clean it off and check the posts) and it rests on several layers of cardboard near my workbench where I can check it periodically. So far, the battery has remained charged without indications of overcharging. For $8 I can afford to pitch the charger if it doesn't perform satisfactorilly. As indicated in another posting, a solar panel would work for a limited time, but I suspect it would overcharge if left unattended for an extended period. I have a single solar panel which maintains the 12 volt, deep-cycle battery on my Apollo gate opener. This panel connects directly to the posts of the battery and has performed nicely except for the time when I tried to operate both the gate and a small electric-fence unit off of the same battery. Even then, it took almost three months of continuous use to discharge the battery to the point where we noticed that the gate operation had slowed down significantly.

 

[desulfator]

Re: Automatic \"Trickle\" Battery Chargers

Most of the ills (failures) suffered by a lead acid batteries are the result of the plates sulfating. A desulfator will bring the battery back to like new condition.

Desulfators work by hitting the battery with high voltage, high frequency pulses. They will remove sulfate deposits that ordinary chargers can not remove.

Plans for homemade desulfators can be found at this link (parts kits are available as well as assembled and tested units).
http://shaka.com/~kalepa/desulf.htm

Here is an extract from an FAQ I've written at the following link
http://shaka.com/~kalepa/faq.htm

For the complete FAQ go to the link above


Q: What is battery sulfation and why does it cause battery failure ?

A: Each time a battery is discharged some of the sulfuric acid in the electrolyte is combined with the negative plate material and converted to lead sulfate crystals which form on the positive plates. These crystals interfere with the chemical reaction neccessary for proper battery operation. When the battery is recharged MOST (but not all) the sulfates are reconverted back into sulfuric acid. This is why a discharged battery will have a low Specific Gravity (SG) reading. Over time the sulfates which are not reconstituted as acid form stubborn patches of large crystal growths that will grow and eventually choke the life out of a lead acid battery. These crystal growths if not stopped will act like ice expanding the cases (bulges), breaking the plates and plate and cell interconnects and causing shorts.

Q: Why does a battery die when it sits ?

A: All lead acid batteries will self discharge forming sulfates in the process. The degree of self discharge will depend on temperature, plate chemistry, and how clean the battery is and how it is stored.

Q: Is there any truth to storing a battery on the ground being a bad idea ?

A: Yes, When stored on the ground the battery will assume the same temperature as the ground. When warmer moist air comes in contact with the battery case, moisture can condense out (like an iced drink in the summer) and increase the amount of self discharge across the top of the case (between the posts). To see this in action take a voltmeter and attach one lead to a post (of a dirty battery) and drag the other lead across the top. You will note an increasing voltage as the probe heads to the other post. To reduce this aspect of self discharge always store batteries on a shelf or on some form of insulation.

Q: How long does it take to desulfate a battery ?

A: That would depend on the degree of sulfation, how clean the tops of the battery is (another route of self-discharge paths), plate chemistry, temperature of the battery and size of the battery. Generally speaking gell cell batts will respond in a week, car starter batteries in a month or so, deep discharge depends on its condition.

Q: How does this pulser compare with commercial units ?

A: All reports received to date suggest this design works faster than what is commercially available.

Q: How much current does this circuit draw ?

A: Normally from 0.040 to 0.050 Amps

Q: Do I need to use a battery charger with this circuit ?

A: Not if the batteries are being charged on a daily basis such as in service in a photovoltaic system or car starter battery