Battery drop

[sailinglegend]

Originally Posted by john61ct

....
> Float is designed to finish off the charge safely.

> So float is really a finishing charge at a lower safer voltage.

No, absolutely wrong. Float is only there to **keep** the bank Full - carry loads, and counteract self-discharge.....

So if I am absolutely wrong why are you absolutely right?

All I'm looking for is some sources with the right information that we can all trust.

Since you agree that Float is not 100% full, then by definition Float is finishing off the charge. We have to blame the battery charger and battery manufacturers for all this confusion.

Originally Posted by john61ct

....As you say, going even 3+ hours holding Absorb too long is not a problem for FLA......

I didn't say that, I said: .... not a problem for 'open' FLAs.

As I suggested the majority of FLA's I see are sealed flooded lead acid - they would not be happy with your charging regime.

You can't just make up your own acronyms and shortcuts like >>.... means something different to >.....and expect everybody to understand what you mean to say. Your posts are very difficult to understand because of this, so please take more time before submitting shorthand messages.

It is very very seldom that you quote references to support why your ideas are correct. I'm challenging you again to quote your sources for your charging regime ideas and your acronyms.

[Twilite]

Originally Posted by Khiimori

Hi everyone.
I am having an issue with battery voltage drop over night. I can have the batteries fully charged according to a Victron BMV-700 battery monitor and a voltage of 12.7V also displayed on a solar control monitor. With only a fridge, VHF and MFD on during the night at anchor the battery voltage drops to 11.8V between 9pm and 5am.
The Victron battery monitor says the ah discharge is around 50 to 60 ah.
I have 5 x 142Ah lead acid batteries as service and 1 as a start battery.
The batteries were new in 2 stages, August and October last year.
I had the batteries equalise charged and tested in a shop last month and was told they are in good condition.
Any ideas as to why and more importantly how to test for the cause?


I am new to the forum so apologise if I have posted in the wrong area or missed a previous post on the same subject.

Doesn't sound like much of a problem to me Especially if you start out at only 12.7, and end at 11.8 running a mfd VHF and especially a refrigerator, and only dropping 9/10 of a volt after running all night. If you leave a charger on with enough amps going to the string, the floating voltage hould climb close to 14.2 . More amps are being drawn at the lower starting voltage than would be, starting with a

higher voltage..

[Pizzazz]

I am contributing so that you can get more opinions. The charging process has been perfected years ago:

1. Put in as much current as the battery will take, watching the voltage go to 14.4V (wet cells). Then hold the voltage there until the current drops to 1% of caapcity, wait 5 min then drop to a float voltage of 13.5V. All these numbers can be slightly different. The consensus here is to hold the absorption phase for a little longer if possible.

This means, you need to observe current, voltage and the shunt needs to be wired correctly (all loads and charger negative to one end, battery negative terminal to the other end).

You do not need to hot 100% charge every time. So, you can set your limit current to 2%, and manually force it to overcharge once a week to cleanse the battery.

Discharging below 50% is bad but only reduces lifetime by half even if done on a regular basis. Chronic undercharging is bad, gets harder to reverse with time. Occasional complete discharge is really bad, a battery can die in a single bad cycle.

I think this is all you need to know. Get the proper monitoring equipment, test your batteries one by one, I think you have a bad battery somewhere, get rid of the offending battery, practice your understanding on the remaining batteries, then replace the set and take care of the new set.

This is one of the issues with large battery banks, ie five batteries. Soon or later one battery will go bad. Before you figure it out, the bad battery will damage the rest of the set. So, now you need to replace the whole set.

[a64pilot]

Float is not meant to be a finishing charge phase, but there is usually some charge that occurs, may take days to get that last 5% in though, but if you tied to shorepower in a Marina, no problem.

It’s Solar and our alternators for those folks that don’t live attached to shorepower that it’s important to not drop to float too early.
My Outback 80 wont watch end amps and drop to float at the correct time, so based on Maine Sails recommendation I have set float voltage to absorption levels, so that it doesn’t ever drop to float, it stays in absorption as long as there is enough light to drive the voltage that high.

On a good day, I may have a hour or so of time that I could have dropped to true float, but not usually, in fact to ensure I’m 100% truly, fully charged every day it takes 30 min of generator run time in the morning, usually.
Catch is that in the morning you don’t know if your going to have a partially cloudy day or not, so just run the thing for 30 min.

Now don’t adjust float voltage to absorption levels on a boat that is left unoccupied on a mooring and not using any electricity, you may can then damage the bank over time.

However I look at it this way, the Lifeline battery is essentially identical to the Concorde aircraft battery, I’ve asked and been told that they are the same.
An aircraft’s alternator is really an automobile alternator and as such outputs between 13.8 and 14.2 V and does so as long as the engine is running.
Absorption voltage for a lifeline battery is 14.3V, the likely hood that .1 extra volt is going to hurt anything if applied for even a couple of extra hours is extremely remote I think, as all automotive batteries are “floated” at up to 14.2V.

However if left plugged into shore power for months, like most boats are, then a lower float voltage that is meant to maintain, and not charge is called for.

It’s not been that long at all that shorepower chargers were either off or on, there was no different voltages, and when on I believe there were about 14V.
I think the big, heavy 30 amp charger that was in my boat when I bought it outputted 14V, I never put a digital multimeter on it, but the analog battery gauge indicated 14V anyway.

[Bleemus]

Just throwing this out there but why do you need an MFD on all night at anchor?

[sailorboy1]

Bet the op has tuned out by now

[a64pilot]

Originally Posted by Bleemus

Just throwing this out there but why do you need an MFD on all night at anchor?

Some use them for their anchor alarm.
My AIS and my NMEA bus are on 24/7, my AIS is my anchor alarm and I like seeing wind speed direction etc is why I leave the NMEA bus powered.

[Bleemus]

Originally Posted by a64pilot

Some use them for their anchor alarm.
My AIS and my NMEA bus are on 24/7, my AIS is my anchor alarm and I like seeing wind speed direction etc is why I leave the NMEA bus powered.

I have an app on my phone for an anchor alarm and for wind I just stick my head out of the hatch. Neither uses my house bank. To each his own.

[Q Xopa]

Originally Posted by sailinglegend

So if I am absolutely wrong why are you absolutely right?

All I'm looking for is some sources with the right information that we can all trust.

Since you agree that Float is not 100% full, then by definition Float is finishing off the charge. We have to blame the battery charger and battery manufacturers for all this confusion.




I didn't say that, I said: .... not a problem for 'open' FLAs.

As I suggested the majority of FLA's I see are sealed flooded lead acid - they would not be happy with your charging regime.

You can't just make up your own acronyms and shortcuts like >>.... means something different to >.....and expect everybody to understand what you mean to say. Your posts are very difficult to understand because of this, so please take more time before submitting shorthand messages.

It is very very seldom that you quote references to support why your ideas are correct. I'm challenging you again to quote your sources for your charging regime ideas and your acronyms.

Agreed that there are some 'high volume' posters that have created their own short hand. It makes their posts difficult to understand.

Usually these posters are quite well researched and contribute a lot. However they also seem to develop some very definite ideas they offer as facts that aren't always backed up by manufactuers or industry experts.

Of course a lot of this stuff is still being figured out and continually refined by manufactuers and experts.

Im all for hearing these ideas and why. But stating as facts and saying the other guys are wrong is not the best use of forum time.

[john61ct]

Originally Posted by sailinglegend

Since you agree that Float is not 100% full

I don't, I made it very clear, the proper profile configuration is that Float should not begin until that 100% Full point has been reached.

> not a problem for 'open' FLAs.

FLA means open, caps, hydrometer, adding water.

There are SLA that are not VRLA, but none are proper deep cycling batteries.

The two deep cycling VRLA are GEL and AGM, Firefly are a unique type of the latter.

> please take more time

write as I like I will. Feel free to ask if anything isn't clear, but usually a quick google will clear things up.

[sailorboy1]

I don’t worry about over charging (whatever that means) my open top FLA golf cart batteries. Adding a little water monthly isn’t much more trouble than just checking the levels.

Man the disadvantages of those old school golf cart batteries just keep adding up

[a64pilot]

I don’t think anyone says that wet cell golf cart batteries aren’t the way to go.
They just won’t fit in my battery box or I would have, I was faced with either trying to build a box that they would fit into, or finding a battery that would fit into the box, I went with Lifelines cause they will barely fit.
Way more money, and they have to be babied, but if you don’t mind babying them, then they are a quality battery.
More expensive though no getting around that.

The value of a Sam’s Club or Costco golf cart battery is very hard to beat.

My next bank may be Gels though, depending on availability and cost.

[sailinglegend]

Originally Posted by a64pilot

.... I went with Lifelines cause they will barely fit.
Way more money, and they have to be babied, but if you don’t mind babying them, then they are a quality battery.....

With Lifeline AGMs you don't need a battery box because they will never spill acid. You can probably shoot a bullet though them and they wouldn't leak because the acid is stored in the Glass Matt - that's why the Military like them!

I'm don't understand why everybody thinks they need to be 'babied' any more than any other Lead Acid batteries. Lifeline say that its best to charge them as soon as they are discharged, and they go on to say that applies to all lead Acid batteries and confirm that all the major manufacturers say the same thing.

Mine have lasted 14 years without any babying - just getting them 100% fully charged overnight on shorepower at least every 10 days, and also equalising about twice a year. If I go for three weeks without fully charging I will equalise then.

[Stu Jackson]

Originally Posted by sailinglegend

>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>


I'm don't understand why everybody thinks they need to be 'babied' any more than any other Lead Acid batteries. ...................... - just getting them 100% fully charged overnight on shorepower at least every 10 days, and also equalising about twice a year. If I go for three weeks without fully charging I will equalise then.

There have been folks with old wet cells who have gone around the world without solar and just an old internally regulated alternator running their bank between 50 & 85% who might consider the regimen you propose as "babying." "Shorepower every ten days..."

[sailinglegend]

Originally Posted by Stu Jackson

....running their bank between 50 & 85% who might consider the regimen you propose as "babying." "Shorepower every ten days..."

....But their batteries didn't last 14 years!!!!
I'm comparing my "babying" with others here who are suggesting getting to 100% twice a week instead of once every ten days.

My main comment was that any regime to add longevity to batteries applies to all kinds of FLAs not only AGMs.