recovering battery abuser another mistake?

[MoncSail]

I recently purchased 2 new Trojan T-1275 12V 150ahr@20hr batteries. They replaced 2 Trojan 30XHS batteries only 2 1/2 years old. Batteries+ convinced me that I abused the batteries by sulfating them beyond repair. So, I am now bound and determined to follow Trojan recommendations, and purchased a brand new battery charger, a ProMariner ProNautic 1240P. The main feature I was looking for is to be able to equalize the batteries, only when needed, using Trojan recommended 15.5Volts. The 1240P has that key feature. However while installing the charger I became concerned about how the charger changes from an absorption phase voltage to the float voltage. Trojan recommends that this switch be made when the current at absorption voltage falls to 2% of the 20hr capacity of the battery. If I am reading the literature correctly this is critical to determining a full charge and thus critical to the life of the battery. When setting up the charger, charge voltages are set based on battery type, but I see no way for it to determine the battery capacity, therefore the critical switch point from absorption voltage to float voltage. ProMariner support, while patient with me at first only stated "absorption time is self-calculated due to battery type and condition and is not adjustable. When pressed for more detail, I was told "this is proprietary information"

So, my question to the community is can a charger accurately determine when a battery is at full charge, when it "knows" only the battery type/charge voltage, the current the battery is accepting, and time. I hope I have provided adequate information for discussion. If I need to provide more detail, let me know.

[djmarchand]

I don't know of any battery charger that you can set to switch to float "at a charging current of less than 2% of rated capacity". All switch to float based on voltage sensed, not current. Some high end inverter/chargers let you adjust the switch voltage.

Trojan's statement is a little suspect anyway. You can always cram more amps into a battery no matter what the state of charge is- just increase the voltage.

But battery chargers do work and don't trash batteries. And the float voltage will slowly over time build up the last few percent of charge. Periodic equalization is your best defense against sulfation anyway.

So, I think you are obsessing over something that you can't control. And if you could the price would be higher than the batteries.

David

[sailorboy1]

There has to be a "regular" smart charger that will do it, as my solar controller will do it.

[harmonysimone]

I love the title of this thread - I am bound and determined to not be a battery abuser (didn't realize they had so many needs!) and hope to learn a bit by following along. Sorry I can't contribute much in the way of knowledge.

All the best,
Harmony

[donradcliffe]

Originally Posted by djmarchand

I don't know of any battery charger that you can set to switch to float "at a charging current of less than 2% of rated capacity". All switch to float based on voltage sensed, not current. Some high end inverter/chargers let you adjust the switch voltage.


David

You need to get around more--2% is the default setting on the Xantrex Link system which uses current, not voltage, but you can adjust both the percentage and the bank Ahr capacity. The Balmar smart engine regulators use time at absorption voltage to switch to float, but if you think you want more charging, simply turn the ignition switch off and then back on and the time resets.

[zboss]

Originally Posted by djmarchand

I don't know of any battery charger that you can set to switch to float "at a charging current of less than 2% of rated capacity". All switch to float based on voltage sensed, not current. Some high end inverter/chargers let you adjust the switch voltage.

David

My mastervolt does that. There is a setting called "Return Amps" for the absorption phase before it switches to float. This setting allows you to not only configure the input amperage as a % of battery capacity but also the time required that the input amps must be below that threshold.

For the original poster... be sure that your Bulk and Absorption voltages are set to 14.8 and 13.2 for float. My Mastervolt had to be configured to those values.

Also, I had to get custom Genasun controllers configured to support those voltages, since they are set at the factory.

[T1 Terry]

In reality, you need to measure state of charge in each cell via the specific gravity of the acid to get a true balance in a lead acid battery. The charging voltage must be gentle enough not to stripe the active material from the plates but high enough to stir the acid up to stop the acid stratifying, water at the top, concentrated acid at the bottom.
Lead acid batteries a such a pain in the butt trying to treat the way the manufacturers want them treated so they will get their claimed cycle life I can't uderstand why people still bother using them. I could understand when there were no other choices, but these days..... why???

T1 Terry

[djmarchand]

Battery manufacturers make up these absurd requirements so that they will have something to deny responsibility when they fail.

Buy good batteries from a major source like Sam's Club who will honor the warranty themselves. But no retailer or battery manufacturer is going to warrant a battery for more than a year.

Lead acid batteries are 1/3 the price of AGMs and that is why I buy them. But I only buy golf cart batteries which I know are true deep cycle. I haven't owned a boat long enough to know when they fail. I owned one for 6 years and the Trojan GC batteries were still going strong.

David

[MoncSail]

Thanks to everyone for the comments. I think we have a pretty good discussion going.
David, without a doubt I can be obsessive about, well almost anything, just ask my wife, guys on the dock,and people I work with. I am surprised that it comes through in just one paragraph. It is in part how I learn. In this case I have bought what should be one of the best (Trojan), and have egg on my face around the dock for getting less than 3 years of light duty service out of an expensive product. I have done a good bit of reading about the care and service of flooded lead batteries, and most information that I trust is similar. Charge at 14.7-14.8Volts until the current reaches 2% maybe 3% of capacity. Less than this, you sulfate, more than this wears the battery. So, now I have purchased a new battery charger that seems to have good press,but I am concerned, and the manufacturer is not providing the information that makes me feel better about my decision. I am hoping that someone here can explain how a charger algorithm might determine correct absorption time when it only knows battery type, the current the battery is accepting, and time. Thank you in advance for your help.

[sailinglegend]

Originally Posted by MoncSail

... I am hoping that someone here can explain how a charger algorithm might determine correct absorption time when it only knows battery type, the current the battery is accepting, and time. Thank you in advance for your help.

On a boat a battery charger doesn't know what current the battery is accepting because the boat could itself be taking a lot of the current for lights/fridge etc.. So a battery charger is designed to "Charge" a battery and not "overcharge" it. So all chargers and solar controllers will drop down to “Float” after a certain time period, 1-3 hours, probably well before the batteries are fully charged - this is the “Charging Gotcha”. The trick is to spot when the charger drops to float and see what current is going in to the battery - via your correctly wired and installed battery monitor. Then turn the charger completely off and back on which will force it back into absorption mode at about 14.7v. When it has stabilised check again to see what the charge current is. When it is 2% at this absorption voltage that is when the charger should have dropped to Float - so you have to lengthen the absorption time of the charger in the setup until this check gives you 2% @14.7v. This will take at least a week to get anywhere near right. If your charger/controllers don't allow you to change the setup this then buy ones that do - or manually turn the chargers back on when they have dropped to Float.

This is the reason many batteries never get fully charged and their life shortened, especially solar chargers, because after they drop to Float there may not be enough hours left in the day to fully charge at the lower Float voltage.

A battery is finally fully charged when the current going into the battery is 0.5% of the Ah capacity of the battery at the absorption voltage. So for a 200 Ah battery this will be a current of 1 amp. To measure this the charger will have to be forced back into absorption mode because it will have dropped down to float long before this.

[sailorboy1]

[QUOTE=sailinglegend;1501383 So all chargers and solar controllers will drop down to “Float” after a certain time period, 1-3 hours, probably well before the batteries are fully charged -[/QUOTE]

My Outback solar controller has a setpoint for both time and current at absorption. Nothing stops me from setting the time to be forever and letting it only go to float when current drops to a certain level.

[sailinglegend]

Originally Posted by sailorboy1

My Outback solar controller has a setpoint for both time and current at absorption. Nothing stops me from setting the time to be forever and letting it only go to float when current drops to a certain level.

Your outback and I believe BlueSky controllers can have the option of a shunt and an extra controller that measures the current that is actually going into the battery and it will then also act as a Battery Monitor. This then tells the charger when to drop to float.

As I said "On a boat a battery charger doesn't know what current the battery is accepting..." - your charger needs the extra hardware to do this and can then give you the option of setting the current to switch to float and and forgetting about the time at absorption.

This is a fantastic system and every charger/controller should have this expensive option, but unfortunately they don't. I fear if they did then 90% of the shunts would be wired incorrectly and most people would be in the same position as with the "Charging Gotcha". Link also tried the same thing controlling a Freedom charger, but it also suffered from a "Charging Gotcha" because of its bad algorithm. Search Google for "link charging gotcha".

Any posting on here has to try and give a general picture - without writing a book - so somethings have to be left out.

[sailorboy1]

Originally Posted by sailinglegend

This is a fantastic system and every charger/controller should have this expensive option, but unfortunately they don't.

was a standard feature of a $500 solar controller, I didn't know it could do it till after as I chose it for different reasons

[MoncSail]

This continues to be a very good discussion, and I am learning a lot. Thank you all. Sailinglegend, I have had a kind of underlying theory that a friend & I have discussed and you may have blown it out of the water, considering the house current requirements. My thoughts are that since we can pretty accurately determine capacity of a battery by putting it on a known load for a period of time and comparing the voltage at start, and at the end of the time, why couldn't someone smarter than me determine a similar curve going back the other way. A specified charge over time results in a charge voltage, indicating state of charge. Not withstanding house loads. Giving the charger manufacturer the benefit of the doubt, they tell me "it (charger) keeps it at this level for a certain time, calculated by battery type and battery condition". So, if I take them at their word, the charger determines condition, but how with limited information. I think this is a worthwhile conversation to continue. How might a charger algorithm might determine correct absorption time when it only knows battery type, the current the battery is accepting, charger voltage, possibly battery voltage, and time.

[Stu Jackson]

Originally Posted by MoncSail

My thoughts are that since we can pretty accurately determine capacity of a battery by putting it on a known load for a period of time and comparing the voltage at start, and at the end of the time, why couldn't someone smarter than me determine a similar curve going back the other way. A specified charge over time results in a charge voltage, indicating state of charge. Not withstanding house loads.

Because it simply doesn't work that way. What goes OUT is easy: amperage times time. What goes back IN is determined by the battery acceptance.

Battery Acceptance by Stu Battery Acceptance


If it was that easy, somebody woulda done it already!