Trojan batteries

[sailaboutvic]

If you select adaptive absorption time the adjustment is automatic, but it is based on the programmed absorption time so it is important to set this correctly.

In the perfect system the absorption time would be adjusted for every cycle. There are controllers that will do this (my previous Outback controller was set up in this way). I think this can also be done with Victron controllers but requires extra (expensive) hardware.

While the above is ideal the adaptive absorption time will adjust this parameter so that it close enough on most cycles. However initially you need to adjust the absorption time correctly for this to occur. The correct setting varies considerably from system to system.

So here the big question
T125 6v in parallel what the setting to sset those batteries ?
And have the setting I been using mean my batteries have been under charge ? Ie when the mppt says there on flat they not been ? .
Don't leave it to Noelex only , lets have everyone option , let see if there at less two answers that match .

 

[sailaboutvic]

Here two photos just taken .
The mppt show it's on float , current going into the batteries is 9.4v
The next photo is the BM .
That show the batteries only except 0.8v .
To me that means 8.6v is being used on the load and because the batteries full it only want to except 0.8v is that correct ?

 

[Graham376]

Some controllers allow for different bulk and absorption voltages. The Victron controllers always select the same bulk and absorption voltage.
The controller is in bulk until the battery voltage has reached the bulk/absortion voltage. Once the battery has first reached this voltage the controller will show you are in absorption mode. If the voltage becomes low enough the controller will switch back to the bulk stage.
So it easy if he blue (bulk) light is on the battery voltage has not yet risen to the set absorption voltage or has risen to this level but has subsequently dropped back below the re-bulk voltage (which an also be set by he user).
If the yellow (absorption) light is on the voltage has previously risen to absorption voltage and has not subsequently dropped back below the re-bulk voltage.

OK thanks understand the bulk/absorption bit but, what's the advantage of "adaptive"? It appears that under the normal setting, the absorption time automatically adjusts regardless of the time setting, as indicated below, soon after I installed the new panels and regulator. How many hours do most set for absorption?

 

[noelex]

The way to set the right adsorption time is to monitor the battery return amps.

This is current entering the battery which will be different to current leaving the solar panels. You will need a battery monitor or a clamp on multimeter to read this.

You also need to monitor the battery voltage.

As the absorption phase progress and the battery becomes more charged the current the battery will accept will be reducing. When this current drops to the correct value the absorption phase should be terminated and the charger should drop to float.

The correct value is set by the manufacturer. An average figure is 1% of the battery bank size. So 4 A for a 400 AHr bank.

If the battery is at the adsorption voltage and the current is less than the 1% figure the absorption time is too long and should be reduced. If the controller is dropping back to float while accepting more than the 1% figure the absorption time should be increased.

Ideally the above should be checked over a few cycles, but once the absorption time is set correctly this will work reasonably over a wide range of different battery cycles.

 

[noelex]

So here the big question
T125 6v in parallel what the setting to sset those batteries ?
And have the setting I been using mean my batteries have been under charge ? Ie when the mppt says there on flat they not been ? .
Don't leave it to Noelex only , lets have everyone option , let see if there at less two answers that match .

Unfortunately there is not one absorption time setting that is correct for all systems. My batteries on this new boat are essentially the same type as on my old boat but my absorption time is about double.

The only way to determine the correct absorption time is to follow the steps in the previous post.

 

[lw395]

Here two photos just taken .
The mppt show it's on float , current going into the batteries is 9.4v
The next photo is the BM .
That show the batteries only except 0.8v .
To me that means 8.6v is being used on the load and because the batteries full it only want to except 0.8v is that correct ?

So, you are running an 8.6A load? What are you using all that current for, in daytime?
Is you problem really quite simple, you use a lot of power and the batteries get a hard (short) life?

Does your battery monitor talk to the MPPT controller? Does that actually work? Otherwise how can the MPPT know when the battery is full, if you're pulling 8A from the system?

 

[Graham376]

Vic, as a matter of interest, are you relying on your monitor to determine state of batteries or, have you done a discharge test with a known load to determine capacity? Why not take one pair off-line at a time and do that?

 

[noelex]

Here two photos just taken .
The mppt show it's on float , current going into the batteries is 9.4v
The next photo is the BM .
That show the batteries only except 0.8v .
To me that means 8.6v is being used on the load and because the batteries full it only want to except 0.8v is that correct ?

This shows your batteries accepting 0.8 A at the float voltage. Unfortunately this does not tell us what the batteries would accept at the much higher absorption voltage.

 

[sailaboutvic]

So, you are running an 8.6A load? What are you using all that current for, in daytime?
Is you problem really quite simple, you use a lot of power and the batteries get a hard (short) life?

Does your battery monitor talk to the MPPT controller? Does that actually work? Otherwise how can the MPPT know when the battery is full, if you're pulling 8A from the system?

We on the move so it all the Instruments, auto pilot, fridge and freezer when they come on and there an iPad on charge .
Bm doesn't talk to the mppt , why would it , it's a battery monitor.
I guess for the little I know that the mppt knows when the batteries are full because it monitor the batteries voltage.

Over the winter mouth we used 95Ah from when the panels stop charging to when they start again , so no we not usei g too much power for a 488ah bank 50% 240ah

 

[sailaboutvic]

Vic, as a matter of interest, are you relying on your monitor to determine state of batteries or, have you done a discharge test with a known load to determine capacity? Why not take one pair off-line at a time and do that?

Did a discharge test , look back you find the Info I posted .

 

[GHA]

To me that means 8.6v is being used on the load and because the batteries full it only want to except 0.8v is that correct ?

Not correct, as noelx said - you need to know what current is going into the batteries at the higher absorption voltage, also seems a bit early to be in float if you really want the batteries to be fully charged.

 

[sailaboutvic]

The way to set the right adsorption time is to monitor the battery return amps.

This is current entering the battery which will be different to current leaving the solar panels. You will need a battery monitor or a clamp on multimeter to read this.

You also need to monitor the battery voltage.

As the absorption phase progress and the battery becomes more charged the current the battery will accept will be reducing. When this current drops to the correct value the absorption phase should be terminated and the charger should drop to float.

The correct value is set by the manufacturer. An average figure is 1% of the battery bank size. So 4 A for a 400 AHr bank.

If the battery is at the adsorption voltage and the current is less than the 1% figure the absorption time is too long and should be reduced. If the controller is dropping back to float while accepting more than the 1% figure the absorption time should be increased.

Ideally the above should be checked over a few cycles, but once the absorption time is set correctly this will work reasonably over a wide range of different battery cycles.

John we about to enter port soon and it getting very windy now need to reef , I come back on your advise if that's ok.

 

[noelex]

Let me use my system today as an example.

My Victron MPPT controllers are set to adaptative absorption time of 2 hours which I have previously determined is about correct.

Today the battery voltage at the start of the solar day was above 25.2 v so the absorption time is 17% of 2 hours which is just over 20 mins.

As expected the app shows my absorption time for the day so far has been 21 mins with 3 hours 34 mins on float (it is not yet 1pm. don’t you love these long days )

The important question is what current was the battery accepting just before the controller transferred to float. As it happens my battery monitor is right next to where I am sitting and I noted the current was around 4.5 A when this occurred today. As my battery bank is 600 AHr this is a little less than desired 1% or 6A. This means the absorption time was a little too long for this cycle. However, the current drops back very rapidly so this result was close enough. It is also better to slightly overcharge rather than uncharge the batteries. Nevertheless if this overcharging is consistent I will slightly cut back the absorption time setting.

 

[noelex]

John we about to enter port soon and it getting very windy now need to reef , I come back on your advise if that's ok.

No problem.

“First fly the plane” is great saying from my flying days that is just as applicable to sailing.

 

[sailaboutvic]

Not correct, as noelx said - you need to know what current is going into the batteries at the higher absorption voltage, also seems a bit early to be in float if you really want the batteries to be fully charged.

P .. until the latest update the victron only had Absortion voltage, so there was no way I could set a time only voltage,
So what's one to do?

 

[Richard10002]

I know many won't agree with me here and they probably right not too has they had a better experience with Trojan but Just keep this in mind if your planning to buy Trojan batteries .

We for many year cruised using cheap batteries £100 touch lasting three to four years then just replacing them for more chep batteries it was working out about £100 per year .
Under three years ago we decided it time we brought some thing better and there been many report how good trojan batteries are and how long they last people ,
So we brought four 6v T 125 given us a usable AH 245 ,
We gone out of our way to look after them , topped up every month, keeping regular check on them and on the deepest discharge we not used more the 20% before fully charging them .
I went out of my way to get good info out best to look after them .
Less then three years on after many test over the last few weeks to check their SOH its working out we have 95 usable AH That's working out £280 per year .

NOW I'm not say Trojan are rubbish but maybe to think carefully before changing from cheap batteries to expensive once.

I had a similar experience with Trojan, (and Rolls), despite being quite anal about looking after them. I have a NASA BM2 monitor, along with a Smartguage, charged to 100% every 2nd day, if not every day, and used low steady tail current to decide on 100%, NOT Smartguage reading 100%.

I have no doubt the failures were to do with me, and not the batteries, but I don't know what more I could have done.

If I were sticking with Lead Acid, I would revert to the buy cheap policy.

 

[noelex]

P .. until the latest update the victron only had Absortion voltage, so there was no way I could set a time only voltage,
So what's one to do?

The later software versions allow for far more user adjustability, but absorption time could always be changed.

However, the way the software deals with absorption time changed completely (about version 1.45 from memory). The technical details are complicated but the bottom line is the change completely altered the correct absorption time.

The new system is much more accurate, but the correct absorption time setting following this software update will be a fraction of the old setting as the way the absorption timer counts down is now quite different. On my system the adaptive absorption time needed to be altered from around 6hs to 2 hrs for the same net result.

 

[vas]

Vas man to man , you said you equalised your once a month , have you actually seen the voltage go to 16.5v? Or have you just set them to equalise come back after some hours seen the equalise setting gone through it time and they back on float .
Cos I actually constantly watch the voltage for some hours and not seen the mppt rise the voltage more then 14.7v , with panels given 80v

sorry, didn't notice that on my mobile before Vic.
YES, when I do set for a MANUAL equalise, and obviously do that when the panels are capable of giving some Amps to the batteries, for that hour voltage is 32.something. So yes, it does work, hope you're not trying to do that in the evening!

V.

 

[lw395]

We on the move so it all the Instruments, auto pilot, fridge and freezer when they come on and there an iPad on charge .
Bm doesn't talk to the mppt , why would it , it's a battery monitor.
I guess for the little I know that the mppt knows when the batteries are full because it monitor the batteries voltage.

Over the winter mouth we used 95Ah from when the panels stop charging to when they start again , so no we not usei g too much power for a 488ah bank 50% 240ah

The MPPT does not monitor the battery voltage, except during the 'bulk' charging phase.
The MPPT controller sets the voltage.
The controller does not know the battery current, it only knows its own output current, because it cannot tell how much of its output goes to the battery and how much goes to loads. One way around this is for the battery monitor to communicate with the charge controller. I don't use Victron kit so I don't know if this should be happening.

 

[sailaboutvic]

Ok back to do battle , hopefully the knowledge people here will bare with me and maybe I and ovths may learn some thing , as it seen it's not only me who lost looking at some of the reply that's been posted .

Noelex I need to go through your posting slowly but before I do
this is how I understand batteries , happy for people to correct me .


Once Bulk charge reach 14.6v it goes into abs , at that point the Voltages start to drop but the current keep poking into the batteries until the batteries accept 3 Amps or less at that point it goes in float charge the voltage at that point is around 13.3/13.4v
Now am I correct if all these factor are reach the battieres must had reach float charge and are fully charge ?
If not why not please