What is the maximum voltage that you bulk/absorbtion charge your house battery at.

[fuss]

I am interested to know the maximum voltages that are actually truthfully being used to bulk/absorbtion charge house banks.
I realise that there are different types, flooded, gel, agm etc but this would have made the poll more complicated.
Some people might have different maximum voltages at the end of the bulk phase from the voltage used during absorbtion.

So in order to keep it simple I have said the maximum voltage and also I have put the equivalent 12v and 24v values.

 

[halcyon]

You do not state what type of battery, they all vary, what suits one is totally wrong for another.

Brian

 

[fuss]

You do not state what type of battery, they all vary, what suits one is totally wrong for another.

Brian

Yes, thats true but then I would have had to have 3 polls....
What is the maximum voltage that you bulk/absorbtion charge your AGM house battery at.
What is the maximum voltage that you bulk/absorbtion charge your GEL house battery at.
What is the maximum voltage that you bulk/absorbtion charge your WET CELL house battery at.

I thought about doing this but I thought it was a bit over the top and might annoy some people. 3 polls looks a bit like i am trying to take over the forums.

 

[Billjratt]

I wonder why you're asking, as it's something we accept with the equipment we use.
I don't think there are many nowadays with the external rheostat fitted.

 

[Gumpy]

My main charger is run from the laptop and the voltage used depends on the power source and temperature.
If I am on my mooring (as I am for 6 months a year) where the batteries are on float (27.4 at this time of year) 99% of the time its set at 28.6 using adaptive charging and with the temperature compensation for this time of year gives 29.6, in the summer its nearer 29. I use Adaptive because it doesnt overcharge the batteries after a power cut as they are never less then 95% charged when the power returns and a long absorbtion period would not benefit them.
If I am running From the genset when away in the summer its set to 29.6 and no adaptive charging just bulk then an absorbtion period of 2hours this gives 30.4 at this time of year and just under 30 in the summer.
One final point just to stir things up I run a full equalistion charge when the batteries are on float about every 6 weeks at 32v.
Charger is Victron combi 3000/24/70A with a Heart interface as backup and to do the EQ charge. Batteries are 5 years old 8 x 200Ah 6V in series parrallel and straight lead acid.

BTW its not on the boat in the avatar but my 20m barge

 

[Stu Jackson]

Rather than guess, one needs to ask that question as it is specific, as mentioned, to the type of battery. I recommend that you look at this manual from Balmar, who make alternators. This manual includes a good discussion of best battery charging regimens as well as a table on page 9 of all different types of batteries.

http://www.balmar.net/PDF/2005-mc-612-manual.pdf

There are literally thousands of other sources, but this table is a very good side-by-side comparison.

 

[fuss]

Rather than guess, one needs to ask that question as it is specific, as mentioned, to the type of battery. I recommend that you look at this manual from Balmar, who make alternators. This manual includes a good discussion of best battery charging regimens as well as a table on page 9 of all different types of batteries.

http://www.balmar.net/PDF/2005-mc-612-manual.pdf

There are literally thousands of other sources, but this table is a very good side-by-side comparison.

Yes, it is specific to the type of battery, but the poll shows some interesting real life situations.
For example some people are bulk/absorbtion charging their battery at greater than 14.9v (29.8v) which makes me wonder if this causes any problems with any dc devices.

Another interesting observation, looking at the Balmar manual, is that the maximum Bulk primary program setting that Balmar use is 14.6v (29.2v) which referring to the poll is less than 50% of what people are using in reality.

I bulk charge at 14.8v (29.6v) and if I could be sure that no devices would be damaged then I would probably increase this a little.

Another interesting observation, looking at the Balmar manual above, is that there is an equalize setting that can be set up to 16.5v (33.0v) and there is no mention of warnings about damage to devices if equalizing (only warnings about damage to batterys) and as this equalizing is done using the alternator, it is not possible to switch off all devices using the master switch. So it looks like Balmar don't think this is a big problem, and maybe it isn't, however I feel that if I did this on my boat then I probably would damage something.

 

[Maine Sail]

With many multi-stage regulators and chargers there is not a bulk voltage setting just absorption and float. While some have it, like the top of the line Balmar regulators, it is a less common voltage setting. There are three or four stages but bulk, with many chargers, does not usually have a voltage setting as it is raising the internal voltage through current to get to the absorption voltage set point. Obviously some chargers & regulators are smarter than others. Not all "smart chargers" are created equal. Some use time only and some use time + calculations of time spent + voltage attained to possibly extend the time in a particular stage of charging if needed.

In bulk mode the charger or regulator is usually outputting max accepted amperage until the voltage rises to the absorption voltage set point, or a time limit is reached. When the voltage rises to this set point, usually around 75-80% of charge, the charge voltage will be maintained at the absorption voltage setting, lets say 14.6 for wet cells for a period of time depending upon the "smart charger" or time + calculations to see if it needs more bulk or absorption charge time. As absorption voltage is held steady, the accepted current of the batteries gradually declines until the charger goes into float mode.

Unfortunately many so called "smart chargers" apply simple pre-determined time settings to absorption time and some do this with bulk too. "Smarter" chargers use a variable absorption time which is based on how long the charger was in bulk mode or calculated time + algorithms.

The question is not just as simple as how much voltage do you apply in absorption or bulk mode. It should include temperature sensing too and battery type because 14.6 may not be right for your deep cycle wet cell batteries when it is 105 degrees in the shade and you could be cooking them......