Battery Charger Questions

[p00ches]

Recently bought a new charger, didn't think it worked right, returned it for another like it, and still am not satisfied. I'm now thinking operator error, and would like some other opinions.

The first one was putting out 15.1 volts (using my digital voltmeter), which is too high for my maintenance-free Deka's. The second one puts out 14.5 volts, still too high. The batteries are not discharged and draw about 2.5 amps in the 4,10,20, and 40 amp settings. They're connected in parallel, with the negative wires disconnected. When I switch to "equalize" I expect 15.2 volts, but get 13.3 volts, with both chargers.

They're Black & Decker VEC1093DBD "Smart" Chargers. My old 20 amp charger, by Vector, puts out 13.3 volts, and doesn't have an equalize function. Black & Decker told me the 15.1 volts is normal.

Is it me, or do I have another bad charger??

Thanks, ...Doug 2003 Journey, 330 Cat

[wa8yxm]

For one thing.. You need to calibrate the voltmeter before you get too upset. Though most of the digital voltmeters I have agree, and at least one is calibrated (There are two ways, onne is to measure the voltage of a FRESH dry cell, note that it is not 1.5, the other is a tad more expensive) there is still occasionally a "Way off" unit sold.

Alas, just off hand I do not know the voltage of a fresh dry cell, if you need it ask me NEXT WEEK, as I'll have unlimited broadband then.

[lwasouth]

Are you reading the voltage from the charger when connected to the batteries, on not connected. Unconnected voltage or open circuit voltage should be around 15+ volts
I would purchase a good 45Amp "Iota" RV charger and wire it in where the old OEM charger was located

[bachler]

Electricity; Is one of the most conterversal subject That can be used around a evening fire.. . 14.5 is what a battery should read when fully charged. A 15 volt battery charger, measured at the output Is acceptable. As a battery has a built in internal resistance. Now they reccommend a battery tender,(trickel charger) as most coaches do NOT have A trickel charger built in there system;; They have what is a very POOR excuse of a battery charger. Most of which if your battery is dead you will be dead before it will get your batterys charged. AS stated in a prior post DO NOT try to get an accurate reading with your volt meater. They are not accurate enough;

[clyon51]

It sounds to me BD doesn't know what their doing, providing your meter is correct. Or you have 2 bad ones.

Boost and equalize should be 14.2 - 14.5. Then down to 13.6 and then 13.2 for maintaining. If you are sure the 14.5 - 15v for your 2 12v batteries is too much, than you don't want this charger at all.

I have 2 Trojan 6v T-105s. Trojan says they like 15.1v, however PD and IOTA (2 top RV charger mfg) will not use more than 14.5v. Now, all auto alternators put out 14.1 to 14.5v, so your batteries can at least handle 14.5.

You didn't mention if your batts where starting or deep cycle. A good charger should have a setting for each.

[clyon51]

Originally Posted by bachler

14.5 is what a battery should read when fully charged.

Not true. When fully charged and right after removing the charger if it was putting out 14+v, the battery will show upwards of 14v.

However, this is a "surface charge" and will slowly degrade to the true voltage of about 12.9v, which can take 1-2 hours.

[BryanL]

Many battery chargers are intended to provide a quick charge on an auto battery. That is not optimum for most RV needs or batteries other than wet cell lead acid types.

You can get away with that type of charger if you are careful. That means making sure that nothing is attached to the battery that could be harmed by the charger voltage, making sure the current into the battery does not exceed manufacturer recommendations for charging, and disconnecting the charger before it overcharges the battery.

Some of the better chargers of this type will have settings for battery type. Manufacturers are reducing the differences such that most of the batteries normally used in RV's won't suffer if connected to a 'generic' multiple stage smart charger.

The 14.5 volt output is telling you it is a multiple stage charger as that is about right for a bulk charge stage. A charger that puts out less than 14 volts is likely a simple current limited only device that will take a lot longer to charge a battery.

The key is what happens after the 'bulk' stage when the battery voltage gets up to 14.4 volts or so. A smart charger will then switch to absorption mode until the current gets down to a low level. At that point it will switch to a topping or trickle charge at 13.2 volts or so. These charging stages will assure a complete battery charge (given time) and keep the battery healthy. Different types of batteries may have slight differences in recommended voltages from what I describe here but most of the time the differences aren't that significant.

In the RV context, there is also a maintenance mode that follows the multiple stage battery charging. This will keep the battery at a full charge without over-charging it and will also apply a sulfation inhibiting technique to help prolong battery service life. One of the best things an RVer can do for the RV batteries is to upgrade the OEM converter to one that provides this maintenance mode as well as multiple stage charging.

[hamguy]

Originally Posted by p00ches

Recently bought a new charger, didn't think it worked right, returned it for another like it, and still am not satisfied. I'm now thinking operator error, and would like some other opinions.

The first one was putting out 15.1 volts (using my digital voltmeter), which is too high for my maintenance-free Deka's. The second one puts out 14.5 volts, still too high. The batteries are not discharged and draw about 2.5 amps in the 4,10,20, and 40 amp settings. They're connected in parallel, with the negative wires disconnected. When I switch to "equalize" I expect 15.2 volts, but get 13.3 volts, with both chargers.

They're Black & Decker VEC1093DBD "Smart" Chargers. My old 20 amp charger, by Vector, puts out 13.3 volts, and doesn't have an equalize function. Black & Decker told me the 15.1 volts is normal.

Is it me, or do I have another bad charger??

Thanks, ...Doug 2003 Journey, 330 Cat

I was the manager of the test equipment and standards lab for a major medical electronics company. They make pacemakers among other lifesaving apparatus. I have a degree in Physics and 30 years in the electronics manufacturing business. That said to define my bona fides, I will say that you are being blasted with bad advice and erroneous information.

1) Where did you learn that your charging voltage is too high. Bear in mind that the output of the charger most likely goes through an isolator which, depending on the construction, may insert an ~1V series drop to the system.

2) The nominal voltage for a 12VDC lead acid battery is 12.6V. Each cell is fully charged at 2.1 Volts.

3) All metrics should include a +/- because all, repeat ALL meters have error. It may be in the 5th decimal but more likely to be in the 1st or 2nd.

4) In order to charge a battery, you must force charging current into it. That means the voltage of the charger MUST be higher than the voltage of the battery.

So to answer your question, measure the voltage at the battery terminals. It should read something over 13.0 to 14.

For more information, see The 12volt Side of Life (Part 1)

Google Deka and get the proper charging information for your specific batteries.

BTW, I would suggest you buy a Precision Dynamics PD92XX as they are made for RV charging use and can keep your batteries keen for years and years.

JMHO

[krautkamper]

You indicated that you have the Trojan T-105 batteries. Those require a bulk charge voltage of 14.8 volts. If you measure 15.1 that is close and depending on the converter you have, should decrease as the batteries charge up. I second the opinion of lwasouth above: The best charger for those batteries is the IOTA in that class. It delivers the 14.8 volts necessary for the Trojans. Most of the others don't. They only deliver 14.6.

[John Hilley]

clyon is right. A fully charged battery will be between 12.6 and 12.8 volts depending on temperature and electolyte.

[Dave78Chief]

You said maintenace free Deka. Is that a wet cell battery or one of their AGM or Gel Cell batteries? Please note, the Black & Decker VEC1093DBD Equalization mode only works when the battery type is set to "WET". Additionally, the B&D documentation clealy states:

Do not use this mode on sealed or valve regulated batteries. This mode is
only meant for wet (unsealed/vented) batteries.

Again, you said "You said maintenace free Deka" which typically means it is sealed and not vented so I would question if you are supposed to use Equalization mode. In addition to the WET battery mode requirement, B&D implemented equalization as a protected feature in that you have to use a ballpoint pen (or equivalent) in order to use the equalization mode. The special Equalization mode is not the Battery Recondition button mode which operates differently.

While the Black & Decker VEC1093DBD is a 3 stage charger, B&D unfortunatly does not indicate in their documentation what their different voltage set points are for each of the 3 stages. However, if the amp rate is down to 2 amps then that in itself is saying the batteries are close to being fully charged (stage 2, absorbtion mode). Now, the B&D charger is primarily designed for the automotive battery industry, so the voltage values may be different than what is used in the normal RV converter industry. The 13.6VDC value used in the RV industry is dual purpose in that it is selected to support both RV loads (primary function) AND absorbtion stage battery charging (secondary function). Please understand that the RV industry absorbtion mode is equvilant to a normal car alternator regulator type of charging (Constant Voltage, Ramped Down Current) except that the automotive alternator operates at approx. 14.1VDC. So, for automotive applications like this B&D charger, a higher absorbtion mode voltage would not be unusual. It is the amperage rate at the set voltage that is of primary concern for this automotve based charger.

The B&D FLoat is also different from a RV Converter. One the charger reaches FUL status, it shuts off an monitors the battery. It will go into a 4 amp Absorbtion mode if it detects the battery level dropping. A RV converter maintains 13.2VDC at a few amps in Float. Both methods work but the approaches are different.

One final note, this B&D charger defaults to GEL cell when AC power is first applied (or cycled) to the charger.

Almost all of this information is taken directly from the Black & Decker VEC1093DBD documentation (http://servicenet.blackanddecker.com...VEC1093DBD.pdf)

Just remember, the automotive 3 stage charger is different than your standard RV converter due to their objects being slightly different.

Dave

[bachler]

Lets not go to the words,, ;;; NOT TRUE ;;;; Unless you can prove it; In printed facts;;; A wet cell on a Battery Is Between 2.2 and 2.4 Volts. X 6 cells= (12 volt batt)14.4 ,,This will vary in the dry/jell cell unit. The average Internal resistance of a wet battery , That we could find in our Electric, Engineering school, was around .07 amps, I want to make it perfectly clear. There is NO way to Measure that, and it will and does very; . The bottom line is 14.5 volts is about where the volt meter should be With the charger hooked up to the battery.. If anyone dissagrees Please SHOW me the Paper work . Because I do not want to give out wrong Information... . IT's about as reliable as saying . Current flows From Posative to negative ;;;; OOPS it flows from Negative to possative.. Just who cares. Just as long as the light comes on when I flip the switch..

[Qwert66]

Great thread - seems that someone can get fully charged up with little to no energy input. I want that charger !
LOL

[Dave78Chief]

Both correct if used in the correct context. Is the battery at rest voltage different from the battery charging voltage? Yes

Fully charged battery at rest will be with surface charged removed and will be approx 12.6VDC (at 75 deg ambient). This is the value you use to establish the actual battery percent of charge.

Voltage at battery during charging can vary from 13.2 VDC up to 14.8VDC depending on the given charger, charger mode, or on some chargers, the user varible settings.

For wet cells:
A car alternator circuit is a constant voltage / varible amperage charger that runs at 14.1VDC. This voltage is a constant value and the alternator amps are reduced or increased to maintain this voltage value. A large number of rigs charge the house batteries while driving so 14.1VDC is the charging voltage while driving.

A old style linear converter (pre 3 stage) will typically output only 13.6VDC charging. This value boiled many a battery dry in the 1970-1995 time frame

Modern 3 stage chargers:
Bulk Mode - Will output 14.6VDC to 14.8VDC at a constant current (charger dependent; a 45 amp cannot put out the amperage of a 60 amp charger). Once the battery voltage reaches this setting (14.6VDC to 14.8VDC), the charger reverts to Absorbtion mode. Bulk mode is used to bring the battery up to 90% capacity quickly however staying at this voltage level will result in very high battery gassing and risking explosion. Many chargers have temerature sensors attached to the negative battery post to ensure the battery does not get to hot (excessive boiling).

Absorbtion Mode - Charger output is typically dropped to 13.6VDC (13.8VDC on some). Amperage is ramped down to prevent overcharging the battery. Voltage is intentionally reduced in order to prevent excessive gassing of the battery. Absorbtion mode is a dual purpose mode. Used to maintain normal system loads (fridge, lights, etc.) and top of the last 20% charging of the battery.

Float mode - Normally set to 13.2VDC with only a couple of amps. Intended to be used to maintain the battery when in storage. Entry into this mode is in various ways depending on the design by the charger (converter) mfg. Some use a time delay after entry into Absorbtion mode (say 36 hrs), others use length of time at minimum amperage draw, while others use a combination of both. Bottom line here is, that you want the voltage at 13.2VDC in order to prevent excessive battery gassing. The 13.6VDC/13.8VDC value of the old linear chargers boiled the batteries dry fairly quick (ergo, the advent of the 3 stage charger).

Please note that high end inverter/chargers allow you to customize your 3 stage battery settings where converters typically do not allow that. They also allow chages to support AGM/GEL type batteries.

Converters and Inverter/chargers are designed to be a compromise between being a power supply for your coachs DC loads and perform battery charging. It is this multiple function requirement that drives differences in design. As I stated above, a normal car battery charger is designed for an automotive application, not an RV converter application.

In the end, you have to put statements about charging in their correct context to properly convey the meaning.

Dave

[clyon51]

Originally Posted by bachler

Lets not go to the words,, ;;; NOT TRUE ;;;; Unless you can prove it

I don't need to prove it, you can do that yourself. Take a 12v battery or 2 6v. Fully charge them, then wait 2 hrs for the surface charge to disapate. (In the books you read, they will explain that). Now take a reading, it will be 12.6 - 12.9v at 75 degrees, depending on the battery. I couldn't care less what a book says, 45 years of practical experience is what I go by.

[BryanL]

seems that someone can get fully charged up with little to no energy input. I want that charger !

yes indeedy! It amazes me how riled some can get looking for differences and reasons to find fault rather than trying to fit everything together in a big plan ...

In the end, you have to put statements about charging in their correct context to properly convey the meaning.

Worth emphasis, I think. -- especially with batteries as the device itself isn't anywhere so definitive as one might think.

[bachler]

Thanks;; For all the information. In my 73 years of experiance ;; the Instructor Once told Me..About people and there experiance and there exact knowelage;; They siad you can take all there information along with $10.00 and get a cup of starbucks.., I ask Well how much is there Information worth then ?????? If you want the facts call DYNO battery In Sesttle. They make there own batteries , My batteries for the motorhome #32 lasted 9 years. At a 14.5 charging rate. But as you can all see. I"M wrong, WHY because a poster said so;; HA HA

[clyon51]

Originally Posted by bachler

My batteries for the motorhome #32 lasted 9 years. At a 14.5 charging rate. But as you can all see. I"M wrong, WHY because a poster said so;; HA HA

Bachler. I never said anything about the charging rate or that 14.5v was not acceptable. Quite the contrary actually. Somewhere our wires got crossed and that is very common when communication is written.

The Only exception I took was to your statement that " a battery is fully charged when it's a 14.5v." If you meant something different, I had no way to know that.

There is no way I know to determine the exact state of charge (100, 75, 50%) while a charger is connected to a battery via a volt reading. Yes certain chargers can indicate a state of charge.

To hopefully clear up where I was coming from and I hope you agree on this point. If I walked into NAPA with volt meter in hand and asked for a fully charged battery, if it tested at somewhere in the vicinity of 12.7 volts and was holding, I would take that battery as being fully charged.

My only point was to prevent someone from thinking if their battery was indicating 14+v while connected to a charger, that it was not an indication of a 100% charged state.

If I'm wrong here on my general points, someone please correct me.

[wa8yxm]

Originally Posted by bachler

...... The average Internal resistance of a wet battery , That we could find in our Electric, Engineering school, was around .07 amps, I want to make it perfectly clear. There is NO way to Measure that,...... If anyone dissagrees Please SHOW me the Paper work . ......

No need to show you the paper work Just a Dictionary will do, epically if it's an electrical/electronic one.

AMPS: is a measure of current flow.. OHMS is how you measure resistance.

Other than that I find no fault with your math but.. I have not attempted to confirm it and like you I only have the approximate voltage in "Memory". (You gave a range).

My suggestion to the O/P.. Forget the portable chargers, Get a decent converter like a PDI 9200 or an IOTA with IQ4 Technology.

[hamguy]

Originally Posted by bachler

Lets not go to the words,, ;;; NOT TRUE ;;;; Unless you can prove it; In printed facts;;; A wet cell on a Battery Is Between 2.2 and 2.4 Volts. X 6 cells= (12 volt batt)14.4 ,,This will vary in the dry/jell cell unit. The average Internal resistance of a wet battery , That we could find in our Electric, Engineering school, was around .07 amps, I want to make it perfectly clear. There is NO way to Measure that, and it will and does very; . The bottom line is 14.5 volts is about where the volt meter should be With the charger hooked up to the battery.. If anyone dissagrees Please SHOW me the Paper work . Because I do not want to give out wrong Information... . IT's about as reliable as saying . Current flows From Posative to negative ;;;; OOPS it flows from Negative to possative.. Just who cares. Just as long as the light comes on when I flip the switch..

I am not trying to pick a fight but I have seen this misinformation printed quite often.


I'm sorry, but a wet cell battery is NOT 2.2-2.4 volts. And if you claim the a resistance of 0.07 AMPS, you display a poor knowledge of electronics. For the 'paperwork' see- From Wiki - Lead acid batteries





These are general voltage ranges for six-cell lead-acid batteries:

• Open-circuit (quiescent) at full charge: 12.6 V (2.1V per cell)
• Open-circuit at full discharge: 11.7 V
• Loaded at full discharge: 10.5 V.
• Continuous-preservation (float) charging: 13.4 V for gelled electrolyte; 13.5 V for AGM (absorbed glass mat) and 13.9 V for flooded cells

1. All voltages are at 20 °C (68 °F), and must be adjusted −0.0235V/°C for temperature changes.
2. Float voltage recommendations vary, according to the manufacturer's recommendation.
3. Precise float voltage (±0.05 V) is critical to longevity; insufficient voltage (causes sulfation) is almost as detrimental as excessive voltage (causing corrosion and electrolyte loss)

• Typical (daily) charging: 14.2 V to 14.4 V (depending on temperature and manufacturer's recommendation!)
• Equalization charging (for flooded lead acids): 15 V for no more than 2.205 hours. Battery temperature must be absolutely monitored.
• Gassing threshold: 14.4 V

For those that understand Wiki is NOT the world's authority on anything see-

BatteryStuff Articles | Guide to Understanding Flooded, AGM, and Gel Batteries

Quoting - 6.Battery Testing can be done in more than one way. The most accurate method is measurement of specific gravity and battery voltage. To measure specific gravity buy a temperature compensating hydrometer, to measure voltage use a digital D.C. Voltmeter. A quality load tester may be a good purchase if you need to test sealed batteries.

For any of these methods, you must first fully charge the battery and then remove the surface charge. If the battery has been sitting at least several hours (I prefer at least 12 hours) you may begin testing. To remove surface charge the battery must be discharged for several minutes. Using a headlight (high beam) will do the trick. After turning off the light you are ready to test the battery.