Battery Problems

[addimaui]

I am looking for some advice re low capacity on my Lifeline AGM bank. House bank is two 4Ds for what should be a total of 420 amph. we tied up to a marina in Nassau, charged to batteries to 100% (per link 2000) with observed 14.2 volts. Disconnected the charger, and watched the system discharge. After 28 hours and 124 amph consumed, voltage was 12.10, which is just below Lifeline's 50% discharge level of 12.2 v. I did run the inverter and tried to consume a fairly consistent output of power, but no heavy use.

I understand the 35% of capacity concept, but think that if the batteries were charged to 100%, with the 14.2 v level, which corresponds to Lifeline's 100% level, that I should have at least another 40 to 60 amph available.

My next move may be equalization - 15.5 v for 8 hours.

I appreciate any advice.

Addi
S/V Koana

[Rick]

Be wary of Lifeline claims regarding Amp-hours. I have never measured one which met the claims. The best 4D that I have measured got 200A-h but it was not a Lifeline.

Be wary of using terminal voltage as a valid indicator of anything but a GROSS indication of state-of-charge and voltage has NO validity as to state of capacity.

Like all deep-discharge lead-acid batteries, AGMs and gel-cel batteries benefit from and acceptance voltage of 14.4 V @20 deg C. Keep in mind that the 14.2V recommendation is made because the manufacturers do not have any idea what type of charging system is used and just when a "trip-to-float" is made. With your Link 2000 you have a very good idea when to trip to float from 14.4V.

Before entering an equalize mode first charge your battery bank with the highest acceptance voltage that you can "fool" the charger into making: set the battery type that gives the highest voltage and set the lowest temperature (if your charger has temperature setting) to get the higer value. Watch the charge current to observe an ever decreasing value under this condition. If the current stays quite high drop the voltage in one tenth of a Volt increments until you observe the decreasing charge current with time. After the charge current decreases to below 20A for both batteries make sure that they are near ambient temperature and rest them if they are not. Then increase the voltage and do it again.

Finally use the equalize mode after resting the batteries for several hours (on float) and, again, look for a decreasing charge current. If the batteries have recovered lost capacity (and are very near ambient temperature) you will notice that they will not charge accept much current even at 15.5 Volts. It is the lack of charge acceptance in conjunction with high terminal voltage at ambient temperature that you are looking for as an indication that you have recovered lost capacity. This may take several charge cycles and time, so have patience.

Another indicator to use is to start this whole process by taking a delta-V divided by delta I measurement using a heavy load like a microwave oven driven by your inverter (obviously with no shore power) for 5 minutes. From a float mode turn of the charging and ac with a pitcher of water in the microwave write down the initial battery current and at what voltage. After 5 minutes quickly note the current and voltage again.

Perform the above processes and after the battery is rested at float make the 5 minute microwave load test again. Compare the two values of delta-V divided by delta I (the change in voltage over the 5 minutes divided by the change in current over that time). Each time that you recover lost capacity the delta-V divided by delta-I value will decrease. When it no longer decreases AND the battery indicates a low charge acceptance (on the order of less than 100mA per 100A-hr rating of the bank) THEN you have done just about all that you can do for the charge equipment that you have.

[addimaui]

Rick, very much appreciate your post. I have been tricking the system somewhat, but did not push accept v above 14.3. Also have to trick it to get to a 15.5 v equalization. I will follow your routine and hope for the best.

Addi

[EngNate]

I agree, Lifeline's AH ratings seem a little liberal, about 15% in my personal opinion (actually I have some history of observations to go by). By that estimate you should be expecting 360AH from your 2 - 4D's. AH capacity rating is based on a 20-hour discharge, that is, a continuous demand of 5% of rated capacity, 18 amps for your bank. Higher demands reduce the total amount of energy available while lower demands increase it to a point. The Link meter uses an algorithm to take this into account, but excessive demand in relation to the bank size can outpace the algorithm (and severely degrade battery life and performance). The highest peak loads really should not exceed 20 - 25% of bank AH rating. Check that the selection of Peukert's Exponent in the Link setup menu is correct - see the manual. Also make sure the settings are correct for battery type & esp. charged %. Note, the Charged V setting has no bearing on the charging voltage. Leave it at the default 13.2. With a Heart inverter/charger, be sure that Power Share is not set down at 5, or accessory loads may prevent reaching full charging voltage, which needs to peak at 14.2 - 14.5, depending on temperature, while the current falls to 2% of AH (individual situations vary). If you have a Heart inverter/charger in the system and the temperature probe was not installed, do it now.

Be sure there are no loads able to 'go-around' the Link shunt. The battery side of the shunt has no connection whatsoever, except the negative(s) of the battery/bank being monitored, and the appropriate meter connection.

I've many times observed discrepancies between a Link and my DVM, a Fluke 87, rated .05% and factory calibrated once since I've had it. Improper wiring practice can affect the Link accuracy.

Battery voltage-to-charge level references are open-circuit, no load at all when measured. Allow a short time for voltage to settle after the load is removed. It's an approximate indication of charge remaining, and most useful, with the Link, as historical data from periodic tests to estimate remaining service life and performance.

I'm not going to put forth an argument, but I am against equalizing a battery/bank that is properly installed, configured, and charged, especially gel's and AGM's - just thought I'd mention it. If you do it, monitor battery temperature continuously. I'm not sure if the Link will display it under one of the function settings, just put your hand on them at regular intervals.

NEA

[Rick]

I'm one of the patent holders on the Link10/E-Meter design and can assure you that the algorithm WILL track peak or continuous current loads beyond 20% of the A-hr rating of the battery (the point at which the Peukert effect becomes significant) all the way to an extreme level.

Such monitors are designed to accommodate heavy pulsed or continuous loads such as encountered by that of electric vehicles. In fact we instrumented hundreds of electric vehicles an recorded data for the DOE and verified such algorithm veracity.

Again, and again, I point out that AGM and gel-cel batteries are merely a subset of the general class of lead-acid batteries. All lead acid batteries designed for deep discharge and high current loads can be equalized. There are a few caveats regarding the process (which, by the way, almost no charger on the market is designed to do properly and, therefore, must be approximated using the existing constant voltage controls that do exist). By definition (in the lead-acid battery world) the equalization process requires a constant current controlled source capable of a voltage compliance slightly exceeding 17V for a 12V battery. Who has that in their boat?

As long as excessive gassing (that which overwhelms the recombination capability for VRLA batteries...AGM and Gel-cel are two of the types...) and excess temperature buildup are prevented there is absolute safety in performing the process. I have "brought back from the dead" many VRLA batteries by doing so. I must point out that I have never had to use the process when the charging system uses at least a 3-step process having at least 14.4 (preferably more using the Amp-hour law) Volts at 20 deg. C. and "tripping" to float voltage at an appropriate time. When charging in this manner cyclical gradual capacity loss is prevented and the internal cell resistance stays low during cycle recovery.

[kimberlite]

can you equalize a lifeline sealed battery.
i currently have 12 group 27 sealed lead acid batteries in series parallel for a 24 volt bank.
fair winds,
eric

[kimberlite]

sorry--they are noyt lifeline but they are delco lead acid.
thanks
eric

[Rick]

Read my comments regarding the concept that ALL lead-acid batteries can be equalized as long as excessive gassing or temperature rise does not occur.

[Rick]

Your situation is typical of a few scenarios which lead to the development of affordable 3-step charging sources beginnning in the early '80's.

Your batteries are being killed by undercharging. Yes, you can charge them manually out of the boat using a relatively low cost automotive charger and a Variac to control the unregulated charger's output. The "automotive" charger needs to have a 16V (or more) ouput capability. Some of them only go to 15V or so and that's where the Variac comes in because they allow you to boost as well as buck the input voltage to manually control the output voltage. You need a good voltmeter and ammeter as well to observe the status of the charge regimen.

Otherwise, buy a "portable" 3-step charger having the highest voltage setting that you can find. In my opinion you should have one that will put out at least 10A at 14.4V or higher and charge your batteries one at a time. Keep in mind that with a wimpy charger you can usually bring up your batteries to exhibit a standing voltage indicative of a "full charge" yet that does not mean "full capacity", does it?

[Rick]

Unless you have a high output current relative to the Amp-hr rating of your battery bank (as do some remote home installations costing tens of thousands of dollars) available from a photovoltaic array you need to have a controller set to float voltage all of the time unless you are manually monitoring the "exposure" of the bank to current. Otherwise you will most often gradually gas the battery bank if near full because the controller will perhaps never reach 14.2V quickly enough to avoid significant gassing.

When looking for a controller for a pv array that has a rated current near 18V for a 12V nominal battery you will get more power from the array using what is called a peak-power-point tracking regulator having a float voltage set point. All of these types of trackers are necessarily high frequency switch mode modules which dissipate almost no energy in converting the panel voltage to the desired battery voltage. So far the marine market does not seem to have these types of controllers being advertised. Look for them in the alternative energy market.

Non peak-power-point tracking pv regulators all dissipate energy which, otherwise, is better put into the battery when needed. If you look at the output current versus voltage curve of any pv panel you can, point-by-point multiply the current times the voltage and plot another curve on top of the other and notice at just what voltage (from the pv panel) the maximum current is for maximum solar exposure. A peak-power-point tracking regulator will allow you to extract the maximum energy for ANY solar exposure,not just maximum.

Yeah, they cost more.

[Rick]

Yes, ferroresonant chargers, in general, do not deliver proper voltage regulation accuracy necessary for your battery banks. That is not to say that they COULD NOT do so it just means that in order to achieve the necessary accuracy the ferroresonant ouput rectified needs to be followed by a voltage regulation circuit.

The original concept behind the ferroresonant technology allowed a relatively low cost "rough" regulation directly from the transformer parameters itself, which were never that good yet better than an "ideal" transformer/rectifer with no regulation following the output.

With the advent of consumer consciousness regarding the need for three-step highly accurate voltage regulation charging approximating the "Amp-hour-law" charging regimen (not that many are aware of that fact) competing chargers with accurate 3-step regulators have essentially "wiped-out" the ferroresonant charger sources. Note that Pro-Mariner (a popular ferro-resonant charger source) has swithed towards the more modern technology in their latest chargers. Aside from all of the previous info, ferroresonant chargers are "known" as being "the big buzzers" making abnoxious noise all of the time.

[Rick]

I am a former "Xantrex engineer" and am happy to say that their original existence was compromised by VERY competent design engineers making products to succesfully compete with the likes of Hewlett Packard in power supply applications. I am also a former Hewlett Packard engineer.

The Truecharge series is good yet do not confuse such "offshore production" with their original "made in Canada" quality. This does not necessarily mean a lower quality it merely means that the original engineering specifications may, or may not, be as equally managed, in my opinion from my experience. To be sure, in general, they are good products, and for sure a good value. They give you relatively small size, weight, and wide input voltage and frequency variation for an output regulation. Wish that they are a little more "settable" for different applications. For the money you will not go wrong. Yes, there are other products that also do well.

[Rick]

Sorry my spelling "check" is undisciplined (my fault only).

[richardm]

Originally Posted by knottybuoyz

Hey Rick

I managed to track down some info on my battery charger as well. It's a Technomin (I believe Canadian Made but no longer in business) "Technovolt" ferro-resonant design. Output voltage is stated at 13.8 nominal. I'm assuming this may also be part of my problem of under charged deep cycles although the documentation says that the unit is designed for all float applications and there is no need for equalization. There are no controls that can be set. I'm assuming, and hope you can confirm, that this is antiquated technology and probably the cause of reduced battery capacity problems. I've had a look around the web at mppt controllers as you suggested and they're too expensive for this small setup.

Rick

I have a Technovolt charger onboard and thought this info may be helpful. I am currently reviewing my charging system. I will attempt to post the document but first I have to convert it to pdf format then to ascii. In the meantime I can email the pdf version of the manual to anyone in need.

richardm

[btrayfors]

Rick,

Do you have any knowledge of or experience with so-called pulsing devices which are touted to de-sulphate battery plates and obviate the need for equalization?

There are a number of such devices on the market -- more coming all the Some of these are combined with battery chargers, others are meant to be standalones.

These devices all purport to greatly extend battery life, to rejeuvenate old, nearly dead batteries, etc.

What do you think of them?

Thanks,

Bill