New Victron MPPT Firmware

[noelex 77]

Originally Posted by RickG

I turn the controllers off and on again to make them go to bulk/absorb faster if I remember.

It is a pity to need to turn the controller off and on. I understand why this is necessary, but with a few tweaks I think you could remove the need to do this.

First make sure you have the tail current option off.

Try setting the absorption voltage of the solar controller a little higher than the absorption voltage setting on the alternator controller. This will prevent the Victron counting down the absorption time when the engine is running (and the conditions are not good enough to charge the battery on solar alone ).

This change will introduce a new problem in that after a long period of motoring the solar controller will still select the full absorption time, potentially overcharging the batteries, but unless you frequently motor for long periods I suspect this will rarely be an issue and the change will charge your batteries more appropriately.

The other option is to alter the rebulk voltage offset. This will cause the solar controller to initiate a new bulk phase more rapidly when the engine is turned off. Once again this will tend to overcharge the batteries and unfortunately this will apply on all solar charge cycles, not just when the engine is running. However by juggling the absorption time and rebulk offset voltage you may be able to achieve better results.

Finally, if you want the Victron to initiate a new bulk/absorption cycle (for whatever reason), there are some better solutions than turning the controller off and on. One option is to program the equalisation voltage to be the same as the absorption voltage. You can then select an “equalisation” cycle which is really a new absorption cycle for whatever time you want. This only works if your batteries don’t require equalisation or you are prepared to alter the voltage back to the correct setting when this is needed.

Note: The above comments only apply to recent Victron software. The older versions work completely differently.

[noelex 77]

Originally Posted by rudykruger

When a battery bank that's just flipped over to float on a partly cloudy day gobbles up 50A when I adjust the MPPT float voltage to 14.4V it's not there yet.

Maybe it's an impossible mission to set an adaptive absorption rule when clouds probably cause the net charging amps to drop low enough for long enough that float is "induced". Just speculating.

When you increase the charging voltage, the charging current will temporarily rise. To measure the tail current (or battery acceptance current) accurately you need to let things stabilise, but if this current is above the desired value for your batteries (and it sounds like it will be well above), then the absorption time should be increased.

It is important to realise the absorption time setting on the Victron controllers is not the absorption time, but rather the maximum absorption time that will be applied when the morning battery voltage is very low. For most cycles the actual absorption time selected by the controller will be much shorter than the programmed time. Thus selecting a 6hr absorption time on the Victron is more similar to selecting 2hrs for most controllers.

The algorithm (without measuring tail current) is never going to charge perfectly on every cycle, but the absortion time does compensate for the effect of cloud cover. The absorption time countdown is only active when the absorption voltage is met. An adaptive countdown timer such as Victron controllers have is normally better again, but the settings need to be correct. As boat systems are highly variable, the default setting are often a poor match, but few owners take the trouble to modify parameters.

[daveNZ]

Originally Posted by Jim Cate

The expert mode with my 100/30 keeps turning itself off. Is this a common flaw and is there a fix known?

Jim

I agree.....My Victron 75/15 also turns expert mode off, but as commented, the settings within expert mode persist.

I also wonder why you need to reconnect all the time, other blue tooth apps seem to manage to stay connected???

Lastly, when exiting Absorbtion mode, the current drops to zero (0.0) for solar output and battery. It seems to come back some unknown time later as the history shows the usual bulk, absorbtion, float times the next day.

[noelex 77]

Originally Posted by daveNZ

Lastly, when exiting Absorbtion mode, the current drops to zero (0.0) for solar output and battery. It seems to come back some unknown time later as the history shows the usual bulk, absorbtion, float times the next day.

When the absorption mode is finished, the output will be reduced to zero until the battery voltage drops to the lower value of the float voltage.

This is normal and all solar controllers behave in this way.

[rudykruger]

Originally Posted by noelex 77

It is important to realise the absorption time setting on the Victron controllers is not the absorption time, but rather the maximum absorption time that will be applied when the morning battery voltage is very low.

Unless you choose the option added last year in 1.42 and enhanced in 1.46 to specify a real fixed absorption time (which then becomes the minimum rather than the maximum absorption time).

[noelex 77]

Originally Posted by rudykruger

Unless you choose the option added last year in 1.42 and enhanced in 1.46 to specify a real fixed absorption time

Yes, there is now the option of a fixed rather than an adaptive absorption time, although this option is strongly discouraged.

The fixed absorption time will still only count down when the absorption voltage is maintained so in many ways it is not just a fixed time, but the time is not modified by the start up voltage.

[doublebubble]

Just wondering if I could get some advise on our Victron mppt controllers, we have two banks of 400ah, (4 x Lifeline GPL-L16T batteries), 770w of solar panels, 3 separate Victron mppt controllers, 2 x 100/30, and 1 x 75/15, each 100/30 run separate panel groups as does the 75/15, basically are all set up with default settings, but should I be adjusting any settings to improve the charging capabilities or not, e.g. auto equalization? We monitor the batteries via a Victron BMV700, the only thing I don't fully understand is the percentage of the tail current setting on the BMV, if this sounds confusing it's confusing to me, any advise would be greatly appreciated.

Regards Rod Lewis.

[rudykruger]

Originally Posted by doublebubble

Just wondering if I could get some advise on our Victron mppt controllers, we have two banks of 400ah, (4 x Lifeline GPL-L16T batteries), 770w of solar panels, 3 separate Victron mppt controllers, 2 x 100/30, and 1 x 75/15, each 100/30 run separate panel groups as does the 75/15, basically are all set up with default settings, but should I be adjusting any settings to improve the charging capabilities or not, e.g. auto equalization? We monitor the batteries via a Victron BMV700, the only thing I don't fully understand is the percentage of the tail current setting on the BMV, if this sounds confusing it's confusing to me, any advise would be greatly appreciated.

Regards Rod Lewis.

Concorde specifies their Lifelines are considered fully charged when charge current falls to 0.5A per 100Ah of rated capacity. That's 0.5% tail current in my book.

[doublebubble]

So would that equate to a tail current on the BMV to be set at 4% for total 800ah battery bank?

Cheers Rod.

[rudykruger]

No, it should stay as 0.5%.

If you had one battery, 0.5% would be 0.5A.

If you have 8 in parallel, 0.5% would be 4A total tail current.

But you noted earlier you have two 400Ah banks. Are they separated with their own set of positive and negative busbars for each 400Ah bank. Or are they combined?

[doublebubble]

They are separate banks but I can parallel them together which we do often which gives us 800ah altogether, correct?

Rod.

[rudykruger]

Correct about the 800Ah but I would doubt the accuracy of one BMV-700 handling two separate banks. That BMV's shunt only gives an accurate accounting of net amps in/out of the system if it is connected upstream of any loads. If you have two separate banks that are paralleled but each supplying 12V to various loads separately I suspect you will be bypassing the shunt with loads from one of the banks.

[doublebubble]

I'll put it another way, lets say both banks are paralleled together 24/7, both down stream of the shunt, all loads go through the shunt, 800ah what you suggest the tail current percentage be set at in the BMV, hoping I'm describing this right.

Rod.

[rudykruger]

Still 0.5%.

That's the simplicity of specifying tail current as a percentage, it stays constant.

In the Victron MPPT by contrast, when you enable Expert Mode in the battery setup area you have to specify tail current in Amps. There you have to do the math to calculate your bank's charge termination amps.

[doublebubble]

Boy o boy more black magic, is there a formula that is to used to determine that, I not sure what you mean by termination amps, apologies for being a bit vague.

Rod