Is There a Point to Float with LA/Liveaboard/Solar

[john61ct]

Originally Posted by a64pilot

Bulk time is determined by charge source size, a tiny charger will stay in bulk all day, a big charger maybe only a few minutes.

Correct

>> Now if we have a charge source that you could set to return a percentage of removed amps and it return 105% of used amps

Ah now I see what you mean.

But no AH counter is accurate enough to be trusted to regulate the charge cycle.

Only endAmps is precise enough. IOW,
> track acceptance rate and terminate at a set rate, then you’ve got something that you can set and it will vary with one day to the next.


> A timer is a shotgun at best, in my opinion.
Timer doesn’t work on shorepower chargers, and then charge rate in known and doesn’t vary, with Solar it does, it you can’t meet it work on shorepower, what chance do you have on Solar?

It is a challenge yes, but as I said, the only reality 99.9999% of charge sources have to work witg.

[noelex 77]

Originally Posted by john61ct

The best timer algorithm is based on a percentage of the time it took to get from start to Bulk.

I believe that's the Victron option you mean.

Some of the Victron battery chargers use this type of algorithm, but none of the solar controllers as far as I am aware.

[john61ct]

I just pointed to manuals that I believe will show otherwise.

[john61ct]

Sorry quotes got mangled

victron "Absorption time multiplier" algorithm

https://www.google.com/search?q=vict...r%22+algorithm

If someone more interested than me could put an "if then and or but not" logic flow pseudocode together explaining all the variables involved, that would be helpful for everyone.

[CatNewBee]

Originally Posted by noelex 77

Some of the Victron battery chargers use this type of algorithm, but none of the solar controllers as far as I am aware.

My MPPT 150/100 smart solar does magic with absorbtion time. On my LFP bank it stays 20 seconds to absorbtion instead of the programmed 15 minutes. Have no idea why they think they should smart out the user settings.

[noelex 77]

Originally Posted by john61ct

I just pointed to manuals that I believe will show otherwise.

The absorption time mutiplier used by the Victron solar controlers is based on the start up voltage. This seems to be exactly what the manual shows on your link.

I cannot see any reference to the time taken from start to bulk. The Victron absorption time multiplier for the solar controllers is based on start up voltage, not on the time taken to reach a particular voltage.

Originally Posted by john61ct

The best timer algorithm is based on a percentage of the time it took to get from start to Bulk.

If you think the manual shows this could you please point out where.

[john61ct]

The start up determines what multiplier is used.

What do you think the multiplier is multiplying?

AFAIK it is "time spent in Bulk" * X = "time spent in Absorb"

I have seen other SCs that let the user set the multiplier directly as well.

But Victron also has a Minimum and Maximum Absorb Hold time, that would override this setting right?

This may be worth starting a new thread.

[john61ct]

Originally Posted by CatNewBee

My MPPT 150/100 smart solar does magic with absorbtion time. On my LFP bank it stays 20 seconds to absorbtion instead of the programmed 15 minutes. Have no idea why they think they should smart out the user settings.

Not designed for LFP, the SC assuming you're already fully charged?

Maybe test with lead at varying SoC starting points.

[noelex 77]

Originally Posted by CatNewBee

My MPPT 150/100 smart solar does magic with absorbtion time. On my LFP bank it stays 20 seconds to absorbtion instead of the programmed 15 minutes. Have no idea why they think they should smart out the user settings.

Yes, the Victron controllers do not use a conventional absorption timer. Even more unusual the reported absorption time is not dependent on maintaining the absorption voltage.

The algorithm is very different to most solar controllers. It will be interesting to see how well it works in practice and to figure out exactly why it makes the desicions it chooses.

Does anyone have any idea the bulk return voltage of the Victron controllers? The manual makes no mention of how the controller decides if another bulk cycle is needed.

[a64pilot]

All these issues that are being pointed out on timer based chargers are why in most instances I agree with Maine Sail, that is that they should manually be set so that they remain in absorption voltage.
No one rule is true for every set up, there are outliers. If your array can make 100 amps by 0900, then likely your an outlier. I think on an average Winter day if Fl, I’m breaking even by about 0900, meaning I’m not discharging, but I’m not doing any real charging either.

Just as another example, look in the Lifeline Manual, it says that for a battery that is 40% discharged, if charged at .1C it will take 7 hours to fully charge.
For me that is 66 amps, at no time will my array make 76 amps for seven hours. The additional 10 is to cover house loads.
I think I have an average bank, and above average Solar, average guy can’t make .1c on Solar, ever. 10% of bank rated capacity out of a Solar system ain’t bad actually.

[john61ct]

Average bank, at 660A?

Not, I bet the vast majority of House banks are well under half that. Maybe for those over 30 foot?

With 660A I'd want 1200+W of solar.

Much less likely be frequently running the genny in the morning before solar charging starts.

[john61ct]

And recognize that LFP with hardly any trailing amps until the very Full point, changes the equations dramatically.

[john61ct]

Originally Posted by noelex 77

Does anyone have any idea the bulk return voltage of the Victron controllers? The manual makes no mention of how the controller decides if another bulk cycle is needed.

Nitpicky I know, but Bulk vs Absorb is not up to the regulator, but the SoC/chemistry of the bank.

Maybe if based just on voltage, it always starts at Bulk anyway.

But a good algorithm for that would be able to raise Voltage as soon as loads started drawing significantly from the bank.

Which again would require coordinating with a shunt / BM

[a64pilot]

Yes, but you don’t float LFP, so that has nothing to do with conversation.
And yes, I’d say average cruising Boat is over 30 ft. Seems from what I see here many are 50 and over.
I can fit 1,000W, and that is more than most on a 40’ average boat.
I’d like 2 kw and a 1,000 AH bank, but if wishers had horses.

To clarify the post about .1c. You don’t need it for the last half day of the charging time of course, you need it at the very beginning, but that’s not when Solar can deliver it. The time when Solar is most effective does not correlate with the time a lead acid bank can most use it, further extending charge times.

[a64pilot]

Originally Posted by john61ct

But a good algorithm for that would be able to raise Voltage as soon as loads started drawing significantly from the bank. BM

When charging, your loads don’t come from the bank, they come from the charge source, unless you exceed its capacity, then you draw from it and the bank.