Float voltage for Firefly batteries

[FlyingScot]

From the Victron 100/30 manual:
1.9.3. Float
During this stage, float voltage is applied to the battery to
maintain it in a fully charged state.
When the battery voltage drops below float voltage during at least
1 minute a new charge cycle will be triggered.

From the Firefly manual:
Reset to bulk phase: for programmable charging sources, adjust the “reset to bulk phase” to occur if the battery voltage drops below 12.0V for >1 minute for the G31 or 4.0V for >1 minute for the L15+.

[FlyingScot]

Originally Posted by john61ct

That to me is like asking for a sledge hammer when standing in a fully stocked Swiss CNC-capable machine shop.

Easy to make your own using tailing amps to reset the BMV then counting AH down at a standard rate (.05C / 20-hr? up to you) in 10% DoD increments, resting isolated a standard time period before reading each V.

And then do a new one each year using the same settings, since the SoC vs Voltage will change

I think of it more as an quick check to make sure you SOC seems reasonable when they are new. Of course after time things change and you get more time with them and understand them better.

Having the mfg. provide this seems reasonable.

Nothing complex about doing them yourself but it's quite a bit of trouble to get an exact constant load and then rest them, then measure and repeat while still trying to have a functional boat. Then you have to trust the SOC display once you leave 'full' and all of it's internal tweaking.

[john61ct]

Originally Posted by FlyingScot

If there is another solution to not float the batteries without draining them, I'd like to do that.

That would be possible, using a cheap batt (starter?) to buffer the load-carrying float, maybe BMV to bring FF bank online if its voltage drops from bilge pumps.

But such complexity may be fragile, not financially justified by the extra FF lifespan

[john61ct]

Originally Posted by FlyingScot

Having the mfg. provide this seems reasonable.

I agree, but given it is guaranteed to be inaccurate and noobs don't understand that, reasonable for them not to as well.

Have you contacted Bruce or FF TS to ask?

[john61ct]

Originally Posted by FlyingScot

From the Victron 100/30 manual:
…
From the Firefly manual:

Very likely FF was using Victron then.

So there you go!

All clear now?

[FlyingScot]

Originally Posted by john61ct

I agree, but given it is guaranteed to be inaccurate and noobs don't understand that, reasonable for them not to as well.

Have you contacted Bruce or FF TS to ask?

Yes Bruce told me "The voltage is a really poor way to tell SOC, as it depends entirely on the load at the time. So you need the properly programmed monitor to track Ah's used to get an SOC while in use. "

And I agree with him, but still would like to have as the dummy check.

[FlyingScot]

Originally Posted by john61ct

Very likely FF was using Victron then.

So there you go!

All clear now?

This is what started my confusion. This didn't clear it up.
I read this as I should have the battery start charging again at 12v but this does not seem to work well in a solar charging environment. Having auto gen start at 12v makes a little more sense.

BTW, I really appreciate your contributions to this thread and others.

[john61ct]

Apparently Victron disabled the CCGX ability to terminate charge based on endAmps as reported by the BMV-712.

http://www.cruisersforum.com/forums/....php?p=2493303

[john61ct]

Originally Posted by FlyingScot

I hope to never plug into shore power again. Definitely not in Curacao where 110 VAC is available but only at 50HZ. Nothing worked well on my boat when I did this.

IMO throwing the baby out with the bathwater.

> I have a combo unit inverter charger (Xantrex RV2012GS with remote panel). I may eventually replace this

If terminating charging based on endAmps is important, check out Magnum + BMK remote. Not for accurate SoC, just the Stop Charging based on endAmps.

Or, maybe better to stick with Victron. Their PowerAssist feature rocks.

[FlyingScot]

Originally Posted by john61ct

IMO throwing the baby out with the bathwater.

> I have a combo unit inverter charger (Xantrex RV2012GS with remote panel). I may eventually replace this

If terminating charging based on endAmps is important, check out Magnum + BMK remote. Not for accurate SoC, just the Stop Charging based on endAmps.

Or, maybe better to stick with Victron. Their PowerAssist feature rocks.

You're right. I was being overly dramatic. I'll likely plug in somewhere so I can run the Aircon in the future. Just not where the power is 50hz.

I would like a new Victron. I'm kind of waiting on them to be upgraded with Bluetooth like the rest of their product line.

[john61ct]

Originally Posted by FlyingScot

This is what started my confusion. This didn't clear it up.
I read this as I should have the battery start charging again at 12v but this does not seem to work well in a solar charging environment. Having auto gen start at 12v makes a little more sense.

BTW, I really appreciate your contributions to this thread and others.

No worries, fun stuff.

Well there are some unclear areas maybe, but I think at least we clearly understand what they are.

As Donald Rumsfeld would put it, no more Unknown Unknowns, at least the Unknowns are all Known.

As a thought experiment.

If you had the engineer who programs the Victron firmware available, what specific Qs would you ask her?

Noelex?

Getting those - or suggestions - precisely formulated, may help advance things along.

[john61ct]

Originally Posted by FlyingScot

I'll likely plug in somewhere so I can run the Aircon in the future. Just not where the power is 50hz.

My (maybe silly here) suggestion is to have charger(s)

that are happy with any mains power worldwide

be the **only** thing that connects to shore power.

And then run all boat-mains loads run off appropriate inverters.

IOW no load devices run directly off shore mains.

That should not be taken to mean high-current loads run for long time periods should/will be run off the battery bank.

As in aircon, should only be run when the bank is supported by ICE (big alts or genny) or shore power.

Unless your boat carries submarine-style battery banks. 8-)

[FlyingScot]

Originally Posted by john61ct

No worries, fun stuff.

As a thought experiment.

If you had the engineer who programs the Victron firmware available, what specific Qs would you ask her?

Why can't we have the MPPT & BMV talk to each other and maintain 0 amps going in and out of the battery? Call it "Steady State".

Example: Battery is 'full' as determined by tail current. Roughly 10 amp load on the system. Solar is capable of producing much more than 10 amps but is limited to exactly what is needed, or maybe just a little more. I start up a larger load, automatically the BMV tells the MPPT's to reach the new steady state.

We could get fancy and apply this to a shore power charger as well.

This would be my ideal.

This could be setup to maintain 100% SOC or a lower SOC as desired.

Originally Posted by john61ct

My (maybe silly here) suggestion is to have charger(s)

that are happy with any mains power worldwide

be the **only** thing that connects to shore power.

And then run all boat-mains loads run off appropriate inverters.

IOW no load devices run directly off shore mains.

That should not be taken to mean high-current loads run for long time periods should/will be run off the battery bank.

As in aircon, should only be run when the bank is supported by ICE (big alts or genny) or shore power.

Unless your boat carries submarine-style battery banks. 8-)

I strongly considered this scenario but space/packaging and current setup of wiring has the combo Charger/Inverter. Even if I upgrade, I'll stick with Victron combo units. My current combo unit 100 amp charger (I've seen 80+ amps from it) has 14.4 / 13.4v settings. I'd prefer less float voltage, but 13.4 should be OK for sometime per the docs.

As a former Trident Submarine MM, and cross trained for the Auxiliary Electrician Forward watch, I can tell you first hand that a Submarine battery bank and my battery bank are on vastly different scales.

[john61ct]

Yes, but so is what's required to run aircon, vs what most people think or are willing to install.

My WAG is one hour per 100AH ballpark.

Good writeup, no time to digest now, maybe others will chime in.

[hellosailor]

Scott-
" a Fluke 365 true RMS meter. Weirdly the Fluke, despite it's price and quality, only reads down to .1 volt. It's more of a clamp on meter with removable jaw. As best as I could estimate there is a 0.05v difference between"
Nothing weird about that, but it does touch on the often ignored issue that when you are trying to get picky about 12VDC charging, you need ACCURATE instruments, not just PRECISE ones.
Fluke rates that meter as being accurate only to 2% on DC scales, with an additional possible error of 5 LSD (least significant digits). Even though the rated resolution is 0.1V, that means if the true voltage is 12.05VDC, the meter could display anywhere from 12.10 volts to 12.00 volts--and it would still be "just" off by those last 5 floating digits. And that's without accounting for the fact that 12.05 volts could be shown as 11.81 to 12.30 volts, simply because of the 2% accuracy limit of the meter.
Add them up, and that meter could read 11.76 to 12.35 volts, and the real voltage would still be 12.05. While most Fluke meters will easily exceed their specs, there are other models that would be more accurate, and many that are also factory certified and calibrated. Without vaguely annual calibration--you can really trust any meter once you start getting into tight measurements.
I'm sure that if you contacted Fluke and said "I want a factory calibrated meter that shows me DC voltage to four digits without any error" they'd find you a FIVE digit model at a considerably higher price, and tell you to put a piece of tape over the rightmost digit because even the best meters do have some float (usually 2-3 digits) on the LSD.

Fluke is arguably the most respected brand of meters, but they still don't make a model that carves numbers in stone.(G)