Does leaving unplugged charger hooked up to battery drain it?

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I store a car through the winter with the negative cable unhooked. This last winter I decided to just hook the charger up to the battery, and shut off the power to te building at the fuse box. That way, when I
do go into the building now and then, and turn on the breaker, the battery will get a shot of charge during that time, keeping it topped up. I just went in there and turned on the breaker, and it looked like the battery was drawing a surprisingly high amount of amps, almost as much as a dead battery would draw. The charger is a decent booster/charger, a Schauer I believe, not really a cheapo. Battery's not very old, maybe a 2 year old Die Hard Gold, and I suppose the battery could have gone bad. But is it possible that leaving the charger on the posts all the time was giving some continuity between positive and negative terminals, drawing it down the whole time?
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blowout preventer wrote:

Put an ohmmeter on it and find out for sure.
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On 3/14/2012 8:50 PM, blowout preventer wrote:

Some do, some don't. Most don't... Use an ammeter to measure any current draw with the charger disconnected, and see what you get... Anything over about 10 or 20 MA (careful that you don't damage your meter, start on a high range and work down) is too much.
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snipped-for-privacy@msn.com (blowout preventer) wrote:

The charger outputs through rectifier diodes[1], similar to the ones in your alternator. With the charger off (or alternator not running), these diodes are the only thing preventing reverse current flow.
A 'leaky' diode in your charger (or alternator), a 'parasitic' current draw in the car somewhere (glove compartment lights were bad about this on some makes/models through the years), or just a bad battery could all explain the issue.
Get out you amp meter, and have at it!
Good Luck!
Erik
[1] In my limited experience with battery chargers I've learned that they usually use the absolute cheapest diodes available... it's amazing they work as well as they do. But then again, charger diodes often have good size heat sinks, and aren't subjected to heavy use, large thermal shocks, vibration and all that like alternator diodes...
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(blowout preventer) wrote:

For a point of reference, my Schumacher XC-103 (which is a semi-automatic SCR instead of diode based charger with an LED display) draws 1mA from the attached 12v battery whether plugged in and not charging or unplugged.
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On 18/03/2012 10:46 PM, Daniel who wants to know wrote:

Look at a SCR as an upscale diode with a third lead to control current flow. Some "cheap" chargers might use the SCR gate to control current and that is the only real regulation they use. Cheap chargers rely on line voltage as the voltage reference.
I am not up on the models, but hope your XC-103 has more than a center tap transformer and just two SCRs. While good enough to get a car going, they are not good to really properly charge up a boat battery to completeness.
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On 3/21/2012 2:13 AM, Canuck57 wrote:

Wonder who told you that bit of swill? An SCR only works on an AC circuit, is never intentionally used as a diode, only as a switching device. Since an SCR won't turn off unless all power is removed, it cannot control a DC circuit (with the exception that SCRs are often used as a crowbar to short the output of a power supply when the voltage exceeds a design threshold.
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On 21/03/2012 6:15 AM, PeterD wrote:

Bullsh1t. SCRs can be used with AC or DC on input, but granted, more often AC to rectify 1/2 wave of the AC. You can use the gate to regulate AC or DC current, but the AC is 1/2 wave rectified.
An example is a DC to AC converter, putting 60 hz into the gate to chop the input DC into a transformer to step up to 120 VAC. Makes for dirty output but works and is common in DC to AC converters you might use on a boat.
SCR is a three lead device, it will do whatever the gate tells it. It is in essence a diode with a current limiter controlled by the gate. Feed in DC, oscillate the gate and you have chopped alternating on the output.
SCRs are NOT only for AC input. Just more BS on your part.
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On 3/21/2012 2:40 PM, Canuck57 wrote:

Once an SCR is turned on, it remains on until the current passing through it goes to zero. It cannot be turned off, an SCR works as an 'ON' switch that once turned on cannot be turned off. Therefore it is only useful in AC circuits or in applications where it must (or should) conduct until power is removed such as a power-supply crowbar protection circuit.
The fact that a battery is connected makes an SCR useless in a battery charger's DC circuit.
Post a schematic of one (an automotive battery charger with an SCR on the output) and I'll apologize, until then, I stick with my point.
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An SCR battery charger has a dual secondary winding, one center tapped, one standard. The standard secondary powers the electronics, the center tap of the other is connected to the ground (-ve) of the electronics and to the battery via a current sense resistor and optional ammeter. Each of the ends of the CT winding is connected to the anode of an SCR, the cathodes are connected to the battery +ve and a voltage sense lead to the electronics.
The electronic circuit "fires" the gates on the SCRs at the proper moment each half cycle to regulate the output voltage and current, IE for full output the gate is triggered at the beginning of that alternation, for less output it is triggered near the end.
The 0 crossing twice each cycle turns the SCR off.
As said this is exactly how the several hundred dollar Lester 24v charger that came with many Invacare electric wheelchairs functions.
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On 21/03/2012 6:15 AM, PeterD wrote:

http://www.sentex.ca/~mec1995/tutorial/triacs/triacs.html
There idiot, found a working circuit with a SCR, DC only, used as a solid state DC switch. See item C.
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On 3/21/2012 2:56 PM, Canuck57 wrote:

Meaningless. It is an ON only device just as my last reply says. No application in a battery charger, just a theoretical circuit.
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On 22/03/2012 6:57 AM, PeterD wrote:

You must be a democrat.
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On 3/22/2012 3:44 PM, Canuck57 wrote:

A democrat is one who would take an academic position and say it would work in a real world application! You took a circuit that was made to demonstrate exactly what I was saying, and tried to make it look like it supported your position...
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On 22/03/2012 2:19 PM, PeterD wrote:

Not at all, I was using SCRs in telecom for 48V DC, a practice application while you were still learning how to BS people.
SCRs are used in both AC and DC applications. Get over it, you were wrong.
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It is in fact a CT transformer and 2 SCRs controlled by a microprocessor, but so what? So is the stock Lester charger that comes with Invacare electric wheelchairs.
http://www.monsterscooterparts.com/24v-8a-dual-voltage-xlr-charger.html
Many electric pallet jack and forklift battery chargers are also SCR based.
True that an SMPS charger is easier on batteries but the SMPS Schumacher chargers don't have a jump start capability either.
The only problem with the XC-103 and I suspect all other models in the same line (XC-75, etc) is that the voltage setpoints are too high. For instance the book (which covers the 75 and 103) and my own testing confirms that it is:
From the book: Charge Voltage: Usually 14.7 volts (Gel Cell), if not, then 15.4 volts (AGM), otherwise it will be 16.0 volts (Standard battery).
http://www.batterychargers.com/Documents/0099001038WB-01.pdf
The problem here is that it should be 14.1 for gel, 14.4 for lead-antimony flooded, and 14.9 for AGM or lead-calcium flooded, hence whwnever I use it on car batteries and AGM I set it to gel, and I don't charge gel batteries with it at all.
The only rhyme or reason I can think of for this voltage discrepancy is that it has no temperature compensation and they wanted it to work even in freezing temperatures where the required voltage is higher. To the charger's credit it does shut down and show an error code if it thinks the battery is going into thermal runaway, which it would likely do on a hot summer day at those voltages if it were set to "normal" on a flooded battery.
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YES, Power flows back through the chargers transformer windings and will discharge the battery. Get a float charger, that's the best for the battery. All my stored vehicles, toys and mowers with batteries are stored with a float charger on them. Got 10 yrs. out of my bikes battery, it still cranked fine when I changed it, just didn't want to trust a battery that old on a long trip. BTW I don't even disconnect the vehicles from the battery when the float chargers on them. Quick discon. plug setups on the float chargers.

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Repairman54 wrote, "Get a float charger, that's the best for the battery. All my stored vehicles, toys and mowers with batteries are stored with a float charger on them. Got 10 yrs. out of my bikes battery, it still cranked fine when I changed it, just didn't want to trust a battery that old on a long trip. BTW I don't even disconnect the vehicles from the battery when the float chargers on them. Quick discon. plug setups on the float chargers. " ***************************** What exactly is a "float charger?" I presume that's not the same as a trickle charger. Could you post a link of where to get what you are using, or similar?
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It's also called a battery maintainer. Harbor Freight sells one for $9.99 and I have one on all my stored battery equipped toys and mowers, etc. . Also use a battery maintainer/conditioner by BatteryMinder that I rotate around the batteries during storage time.
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Repairman54 wrote: "Also use a battery maintainer/conditioner by BatteryMinder that I rotate around the batteries during storage time. " ******************************* Thanks for the info, I googled Battery Maintainers and saw many which claimed to be able to "de-sulfate" batteries. I wasn''t aware that could be done -- but I'm inclined to think it's legit since so many battery maintainers claim to be able to do it, one of which was made by Sony. A comparo indicated the BatteryMinder was the best one. But how is it possible to de-sulfate a battery? I thought they were toast once sulfated.
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