I have a quick question about homebuilt battery tenders. If someone is using a small wet cell 12V motorcycle/tractor battery to power their T, will the homemade battery tenders made from the wall warts still work or are they too powerful for the small batteries? Thanks.
If the battery tender is a float charger (and the very name "tender" implys a float charger) it will not hurt even a small battery.
Float chargers work as a fixed voltage device, usually around 13.3 volts, but I've seen them ftom 13 to about 13.8 v. My personal opinion is that 13.3 volts is ideal.
I have made many of my own but nowadays its cheaper to buy them for as little as $8 from amazon or even Harbor Freight. I have also taken apart a harbor freight charger and the circuit is a common one and just fine for a float chatger.
Keep in mind that if you deeply discharge your battery a simple float charger may take some time to return it to full charge. Most of the cheap chargers max out at about 1 amp, so if your motorcycle battery is a 20 amphour battery (common) and you discharge it half way, it can take up to 10 hours plus to recharge it.
The good news is that a proper float charger can be left on a battery indefinitly - so no worries there!
You cannot interchange 6V battery and 12V battery and continue to use the same wall wart and same bulb. The unit I designed and many of you guys have used is for a 6V battery and uses a 9V wall wart and a 12V small bulb. The 9V wall wart and 12V bulb are easy to find. To make a 12V version of the same thing you end up needing to find a small 24V bulb and an 18V wall wart and those are not so easy. I think you need to look at commercial devices for limiting the current when needing a 12V flea power charger.
Looks like Bud and I were both typing at the same time but I am talking about a different type of charger than Bud is. His is a constant voltage type and will in fact charge the battery while mine is a much simpler constant current type charger and is often referred to as a "flea power" charger to just keep the battery "up" and free from self discharge on vehicles that are going to be stored until spring and have had their batteries charged first.
The term "Battery Tender" should not be confused with the flea power devices above. The "Battery Tender" brand will fry a 6 or 12 volt battery if left connected for significant periods of time regardless of claims by the manufacturer.
Ron the Coilman
I am looking for something that can keep the batteries topped up during periods of inactivity. I always like to keep them topped up, but I don't always have time to charge them. That is why I liked the "flea power" ones. Thanks.
OK then for us life skilled impaired spark chasers
I take it the 'Lizzard' brand is what would be defined as the constant voltage type? And that what is being said is that this type is probably OK during the season but for a winter over should be unplugged?
I just found out about 'Lizzards' this time last year and other than driving out the garage door and finding them trailing behind (do NOT install the connection on the drivers side is THAT message) I thought I was doing myself real good as where they keep the battery level the starter just loves for the 2-3 revs it takes to start the cars.
I'd like to really understand and if they should be unplugged for the winter that would be a service to the rest of us who use them.
I installed a lighter receptacle at each end of the ol' brass picup, and anchored a plug on a long cord at the end of the garage. I never bother unplugging it, as pushing the car out of the garage does that.
The other end of the cord is an automatic battery charger capable of 10A, but it keeps the battery at 13.8 indefinitely.
I have a battery minder,I got mine at Northern tool,bought a new motorcycle in Nov. 04,it has 7000 mi. on it and has same battery,the battery minder has been connected since new, never a problem,also a 05 Dodge with two orginal batteries ,keep minder on it also,don't drive it much,also three model A Fords with minders connected,never a problem!
Just a few notes here. Whatever "charger" you decide to use, make sure that the part that plugs into the wall is UL approved but also then make sure that if you unplug the device while the charger is still connected to the battery that there is absolutely zero drain on the battery back through the charger. This reverse battery drain issue is not uncommon on ordinary chargers that are not designed to be left in place 24/7. The reason it is important is that you might have a power failure back home in the garage while you are away on a tour and your "battery tender" can destroy your battery if it draws the charge off of it during a power outage and there is nobody there to disconnect the charger. There are a myriad of chargers out there and they change constantly. Most of the "fancy" ones that cycle the battery periodically do way more harm than good. There is more BS out there for batteries and by battery charger makers than almost any other market. This is a market that thrives on misinformation.
Kindly please explain why you believe the Battery Tender brand by Deltran (if that is the brand you are referring to) will fry a 6 or 12V battery if left connected for significant periods of time. I am interested because I have both a 6V and 12V version of these connected 24/7 and have never had any problems.
I would love to be more knowlegable about these things instead of just believing what the manufacturer says (or does'nt say) on the packaging.
John or Ron or other, please elaborate what we should know so we will be more educated users/purchasers of these products. Maybe some do's/don'ts.
I have a cheapy H.F. small digital type that does 6V and seems to work but makes odd sounds (internal fan bearings?) so I am getting less happy with it.
Also have the "Battery Tender" brand float charger that seemed to work well on my 12V motorcycle battery in the Honda C-70.
Hate to open another kettle of fish , but I just built a magneto charger (no generator on my car)built exactly per John Regans old diagram and it is working very well so far. Perhaps I will need to use the charger less now. Is there any way to wire this so the charging shows up on the ammeter?
I had a battery charger set on the battery for our Mustang convertible. I hooked it up about December, then didn't really go to the garage until March or so... and my battery was dead. I had it on the lowest setting (2 amp?) and it was completely dead. 0 volts. Completely shocked me, I thought I could leave it hooked up.
Now, I just disconnect it and leave it on my wood workbench til spring, then charge it if it needs it.
Why would it have been killed on 2 amp charge- kind of like what Mike Green is asking?
Thanks in advance!
Because two different D-tran Battery Tenders croaked two different expensive 6 volt batteries for me after leaving them connected over a long period of time.
I do use a battery tender to recharge my 6 volt bench battery, but I NEVER leave it connected for more than 24 hours and then connect my flea power maintainers.
Ron the Coilman
The old fashioned battery chargers that are designed to charge quickly and often have a 2 amp setting are not float chargers and cannot be continuously connected to a battery.
If you want to know if your float charger or battery maintainer can be safely left connected to you battery indefinitely, do this: Connect the charger to the battery (we're talking about 12 V standard lead acid batteries) and leave it until you sure the battery's fully charged. Then measure the voltage accross the battery (charger still connected) with a digital meter. It should measure very close to 13.5 to 13.6 volts (6.25 to 6.3 V for 6 volt batteries). Slightly lower to 13.3 volts is OK. Battery size makes NO differance.
I have maintained 400 and 800 amp hour battery banks on yachts for over 5 years this way and after 5 years the batteries had lost very little of their original capacity.
Two guaranteed ways to ruin a battery: 1.leave it sit partially discharged for a while and 2. allow the electrolyte level to fall below the top of the plates. They will also last MUCH longer if you don't discharge them much below the 50 % level.
The float voltage for a 6V battery is NOT 6.25 to 6.3 since that is even below the open circuit voltage of a battery not on a charger. I think 6.75 to 6.8 is what you meant but usually 6V batteries can go higher on float so long as the voltage is temperature compensated to go up and down with battery temperature. Without that feature and careful control to keep the battery and the charger at the same temperature, I think you would be doing your batteries more good by just charging them up all the way and then hooking them to a constant current flea powered charged to just keep the self discharge neutralized while they are parked for long periods. In that mode the long term life of the battery is maximized.
I've had batteries that lasted 10 years. When not in regular use I put on a charger for a couple hours every other month, or so, and they've performed well.
Leaving something like that connected to a battery ALL the time is asking for a call from the fire department.
I have a friend who lost half of his steel warehouse because of some electrical problem with a semi tractor.
Why tempt fate?
You old radio guys know tube cathodes or heater filaments are rated at 6.3 or 12.6 volts. That's the voltage out of a fully charged battery after the surface charge from charging is dissipated.
6.9 and 13.8 are the voltages it takes for a charger to get the battery to full charge. That takes about 50ma on the typical car battery.
A limited current charger of, say 50 ma, is safer than a constant voltage charger, because a shorted cell can entice the constant voltage charger to overcharge the remaining cells, sometimes with disastrous results.
Regardless, I use an automatic charger.
Your correct of course. 6.75 to 6.6 is the proper float voltage for a 6 volt battery. Apparently in my dotage I can no longer divide by 2. ;o)
Your also correct that temperature is important and 13.6 volts can be to high at high ambient temps. Thats why I prefer to reduce float voltage to 13.3. It is sufficient in my opinion and has served me well even through summers in Houston, TX.
Technically batteries stacked in racks have to have the top rack maintained at a slightly lower voltage than the lower racks due to temperature gradient.
On the whole though, I have had much better luck with constant voltage floating than with constant current. To each his own.
I had this on my site for a long time:
Partly extracted from the MTFCI Forum, Nov. '03
Tim M: He went to un-hook the new 12v battery from the charger .... KA-BOOM! It sounded like a pistol went off in the shop. When he unhooked the charger, a spark set off the hydrogen fumes from the battery and blew the caps off and the side out. I was hollering, "Is it in your eyes?" but he couldn't hear me because he was deaf from the explosion. Got him out to the hose and washed his head (told him to get the baking soda but he wouldn't); just burned his forehead a little. He was happy today that his hat is OK.
Doogie: we set the battery on the charger, and forgot about it for about a week. Boiled it dry almost. I never bothered to check. Turned the key and KA-BOOM! Battery exploded.
Alan P: While working on my riding mower, I leaned over to crank it and BANG !! Blew the entire top off the battery, showering me with plastic and acid, The force of the explosion ruptured my left eardrum and cancelled a much anticipated dive trip to the Keys. Gave me a healthy respect for lead-acid batteries, and the explosive properties of hydrogen.
Marvin: Yes it can and will happen. I am a slow learner as I have blown up 5 of them: 6 volt, 12 volt, and one 24. I am still in one piece but lucky. I was leaning over the 24 and all that saved me was it blew the bottom and sides out and not the top. My hearing isn't too good anymore.
Bove: I learned that lesson when I was 15. I charged batteries with a Nash generator driven by an electric motor. All I did was remove the wire from the battery after charging and BANG! The battery side was blown completely off and I ran to the cellar sink. I survived just fine and never did that again. One should learn something every day.
Jackie Z: Took the three mile drive down to Wally World one hot summer afternoon in my '77 Granada. Was in the store about an hour. When I got into the car and hit the switch, I heard the starter pull in and then there was one loud THUD and the right hand front corner of the hood jumped up. I then had no further electric power. I found that the battery case top was now seperated from the body of the battery on two sides.
Ed, MI: For you tough folks out there, these batteries aren't filled with hydrocloric acid, the stuff in your stomach, but SULFURIC acid, which is much, much, stronger stuff. You play and you WILL pay.
BG: I left a "no maintenance" battery on my Sears 6-amp charger for several days, and it blew while I was away. Made quite a mess. Does anybody have an idea why this happened?
Ricks: Fixed rate chargers are bad news. Once a battery is fully charged, it takes only a few milliamps to keep it up. . It will absorb additional current, but that all goes into heat, and into breaking down the water into hydrogen and oxygen - in the perfect ratio to explode. 2.3 volts per cell is the magic number not to exceed if you want to keep your battery a long time, and not boil out the water. That's 6.9 volts for a 6 volt battery, and 13.8 for a 12 volt battery. Automatic chargers are the only good ones. Schauer had the first good patents, having bought them from my late neighbor nearly 40 years ago. . Chargers are like comparing a third brush generator to a modern one. If a charger doesn't say "Automatic," use it only for metal plating and de-rusting.
When an automatic charger is connected to a fully charged battery, there is almost no current flowing, and no spark when disconnected. . Nevertheless, always interrupt current flow a safe distance from the battery. Unplug the charger from the wall first.
For safety sake, and for the life of your battery, use only Automatic chargers. . Don't even use a trickle charger or "Battery Maintainer" unless it says Automatic - and its detailed description specifies "float charge" or less than 100 milliamps final current. They get ridiculous prices for those battery maintainers, and for less money you can get a 6 or 10 amp Schauer Automatic that will safely maintain a battery indefinitely.
I've mounted cigar lighter receptacles out of sight on the front and rear of the old brass picup, and under the front bumper of the wife's saloon, so I can keep either one or both fully charged. . I then have an anchored cable going to the Schauer Automatic. As the car leaves the garage, the cable drops safely to the ground.
The hydrogen and oxygen that explode batteries are released only when a battery is charged at too high a rate, or overcharged. Otherwise, you would be adding water all the time.
* Jump-starting: always connect the hot side first, then connect the cold side to the bumper or engine - away from both batteries.
* Charger: always connect to hot side of battery, then cold side, then apply charger power.
* Disconnecting battery: Don't touch hot side - just disconnect cold side, preferably away from the battery. Once the cold side is ungrounded, no current can flow.
* Make sure all hot battery connections in your car are covered by insulators at all times. This will protect from the wayward wrench.
* Inspect your battery for signs of leakage - liquid splatters or corroded terminals. Those are sure signs of dangerous overcharging.
*One more precaution: a battery can develop a short in a cell at any time. When that happens, The remaining cells get overcharged - even by an automatic.
PS, Marvin, my distant cousin from Montana, passed on several years ago.
Mr. Regan, you noted you had designed a "Flea power charger." Do you produce this device? and if not where is the circutry described. You mention a "wall wart?" What is that? This long term storage is a problem I have with batteries. My current approach is to check battery voltage frequently and drive the cars as often as I'm able.
Amazon currently has the 6V CTEK chargers at $34.59 with free shipping (U.S.).
I have no experience with the CTEK 6 volt chargers, but my 12 volt
7002 model does everything that itís claimed to do, and does it well.
Iíve been using it for 4 years on a Ford F150, and my son in law has
no complaints with the 3300 used on his Corvette for two years or so.
Neither of these vehicles get out much.
CTEK website is here . . .
I have the 6v and 12v CTEK chargers also and they have both worked great for me.
I don't produce the small so-called "flea power" charger but they can be built easy enough. All you need is a 9V DC wall power module that is rated about .2 amps DC. Since you will be leaving it plugged in - make absolutely sure it is UL approved and not something you have doubts about. Besides that you need a very small 12V dc bulb. I think the one I used is either a 1516 or is it 1615. I can't remember but the idea is to get about .05 to .075 amps to flow continuously through the battery while it is in storage to prevent any self discharge. Your current method is in fact ideal since the idea is to basically keep your battery fully and completely charged at all times without overcharging it. The flea power chargers can be built for less than $5 but only work on 6V batteries since a 12V version requires 18V module and 24V small bulb and both of those items are not commonly made. 9V power modules can be found powering old calculators or at almost any surplus store. They rarely cost more than $3-$4. Don't get a super powerful one since they put out too much voltage. The module does NOT have to be a regulated unit just look for one rated between .15 and .25 Amps DC.
This is the flea power I made useing Johns instructions. Works good for me. At the time, Johns instructions called for a #1816 12v .33 amp bulb, that is what I used. Les
What is the small black box above the light in your photo? Is it just a junction block? And which wire did you hook to the red clamp--the one from the light?
Joseph, That is a junction block. On mine, the red clamp goes to the junction block. When you hook the clamps to your battery, the bulb should just glow. If the bulb is bright, just reverse the clamps. It all depends on how you hook the transformer to the junction block. Les
In the FWIW dept...
http://www.harborfreight.com/automatic-battery-float-charger-42292.html?ccdenc=e yJjb2RlIjoiNTQxNDYyMjkiLCJza3UiOiI0MjI5MiIsImlzIjoiOC45OSIsInByb2R1Y3RfaWQi%0D%0 AOiIxMTQxIn0%3D%0D%0A&utm_medium=email_direct&utm_campaign=5111b&utm_source=1003
Some say it is good, others point out the drawback.
I don't see a UL mark on the power module, Some have warned about the same thing I warned about namely that if you have this on your battery and the AC power goes off, the charger will then drain your battery. I have no first hand knowledge of this charger but just reading the reviews. I CAN tell you that both of the BATTERY DISCONNECT switches that are advertised on the same page are in fact "TROUBLE with a capitol T and that rhymes with P and that stands for Pool..." but everything there is certainly cheap enough to be attractive to us T people. An unattended battery charger is not a place to consider price as being important until after you have found a few chargers that will in fact work safely and then are choosing between them.