Victron DC/DC Charger "Max Bulk Charge","Absorp. Charge' Times?

[Wallowa]

Can't find a reference for what the "Bulk Max Charge" and "Absorp Charge" times should be set at....this is on a Victron Orion 12/30a Non-Isolated DC/DC charger for a BB 100aH battery.

If you could list your time settings and the logic behind them I would appreciate it.

Thanks,

Phil

 

[Jon R]

Hi Phil,

Those features are for optimization of the charging of lead-acid batteries, and are not needed for LiFePO batteries. My battery is a different brand with prismatic cells, but the chemistry is the same. My manufacturer just says “set everything at 14.6 volts, set absorption time to zero, and disable float.” You can’t quite do that with the Orion. I use 14.2 volts because I have a 204 Ah battery and don’t need to maximize capacity. So all voltage settings are at 14.2 and I have the absorption time set to the minimum (which I think is 1 hour on the Orion). I have the camper off the truck right now and the Orion apparently operates off of the truck voltage because I can’t see it on the Victron app to look at the settings.

 

[Wallowa]

Jon,

Thanks....when you say "Those features..." what are you referring to ? I set my absorp to 14.4 [712 100% charge is at 14.2 and balancing cells requires 14.2+ for 15 mins] and have the Orion absorp time at min...1 hour......the "Bulk Maximum Time" has me stumped....originally the default is 10 hrs; I reduced it to two hours...what is correct?

Lastly, am I correct in assuming that all my Victron charging devices [IP67, 100/30 MMPT and Orion 12/30 DC/DC] reduce the amperage going into my BB battery over time at specific voltages? In short, voltage will stay at rates set in settings, but amperage will decrease as battery approaches 100% SOC? What actually causes the amperages to decrease?

Thanks for the insights and recommendations!

Phil

 

[Vic Harder]

Phil, I believe Jon R is saying that THOSE (Absorb Charge & Bulk Max Charge) terms are relevant to Lead Acid batteries, and not really the right language to use when discussing LiFePo4 batteries. Yet the terms are still there because our charging gear can charge both types.

For LiFePo4 we don't care about Bulk/Absorb charge times. We use the settings (Absorb Voltage) to set the voltage level, but don't need an "Absorb" phase in the charge. Essentially, we Bulk charge and then float. 2 phases. Traditionally, good Lead Acid chargers go through more phases (bulk, absorb, float, Equalize) to ensure good charging.

Practically, that means we set Absorb time to be as short as possible and Equalize time or voltage low enough that it never kicks in.

Amperage going into the batteries decreases as the battery fills up, naturally resisting getting more charged up. Lithium batteries have far less such resistance than lead acid batteries, hence we don't need an absorb phase.

Make sense?

 

[Wallowa]

Vic...yes makes sense and thanks...but if we in affect only charge with the bulk phase, does the time of that phase make a difference? The setting on the Orion DC/DC lists it as a maximum time limit for bulk charging, so can it be set too low to accomplish the full charge needed? What triggers the bulk to end and switch to absorp? Battery resistance? I asked this question of BB and have not received an answer.

Thanks again to you and Jon.

Phil

Ps...A thought, if bulk charges at the max amperage, 30 amps in my case, then the Absorp tappers off the amperage based on battery resistance and while we can fast charge an Li battery, slower charge produces less heat and extends the battery life...or does the charge voltage determine the speed of the charge. The change from bulk to absorp definitely so far has never approached the 'maximum' bulk charge time limit, so perhaps amperage into the battery is solely controlled by the internal resistance which increase with SOC; while the speed of the increase in SOC is controlled by the charge voltage. Hell, I don't know!

 

[Vic Harder]

I would set my bulk time to unlimited... 14h or more. The trigger to absorb is determined by logic that matters not for Li batteries. Li batteries just suck up the juice until full (tail current) vs how Lead Acid batteries work.

 

[Wallowa]

Afraid to ask, but what does this mean: "The trigger to absorp is determined by logic..."?

 

[Vic Harder]

You sure you want to know? More info than I care to read right now...
BU-403: Charging Lead Acid - Battery University

 

[Jon R]

In the Orion, absorption is triggered by the battery voltage reaching the absorption voltage you set in the battery settings. Again, my battery’s seller recommends just setting the bulk, absorption, and float voltages to the same voltage, which should be close to but not more than the maximum charging voltage recommended by Battleborn (14.6?). If you don’t need the absolute maximum amount of storage the battery can provide, using a lower voltage than the max reportedly increases battery life. I use 14.2 as I said.

The maximum bulk time limit setting I believe is intended to allow the user to set a time limit to avoid excessive electrolyte boiling in a lead acid battery. This is not applicable to LiFePO so as Vic said set it to a high number. I used 8 hours. 8 hours x 30 amps is more than my battery capacity of 200 amp hours. Also, my truck is never going to run that long without shutting the engine down, which restarts the cycle anyway.

The Orion manual provides a good discussion of what all the settings do. I recommend reading it if you haven’t. Use the on line version on a decent size screen. The paper manual was really small print.

 

[Wallowa]

Yup, read the manual several times, what you two have provided fills in the holes not explained in the manual...I will cease and desist future inquiry into the mystery of all this....the voltage I also use is at the low range of what BB recommends 14.2V [14.2-14.6V]...the reasoning behind the length of time the bulk will run [since both bulk and absorp are at the same voltage] in my case with a 100aH BB would be at a 'maximum' of 3 hours...30 x 3 = 90A; thanks for that Jon...actually see the bulk amperage drop rapidly in much less time since I have used very little from the BB so I assume the bulk is also truncated by the BB as it approaches 100% SOC...then absorp reduces amps even more...seems to be a curved reduction in amperage. Only blip in my programming will be to occasionally run a charger to 14.4 V for 15-20mins [BB recommendation] to balance cells in BB; solar would be the logical one for this.

So yet again, thanks for your patience in answering my myriad of questions...it has been appreciated.

Out Here....
Phil

 

[Wallowa]

You sure you want to know? More info than I care to read right now...
BU-403: Charging Lead Acid - Battery University

This was at that LA battery site:

https://batteryuniversity.com/article/bu-409-charging-lithium-ion


Details of what we have been discussing...thanks.

Phil

 

[Jon R]

Hi Phil,

I didn’t mean to discourage you from asking questions by referring you to the manual. I just had looked at it to make sure I provided correct information and saw some good explanations of some of the things you had asked about that I thought might help. I’m happy to continue trying to help.

Jon

 

[Jon R]

In bulk charging the charger is supplying whatever voltage is necessary (up to the voltage limit you set for bulk charging) to deliver the rated current of the charger.

When the battery voltage rises to the absorption limit you set, the charger switches to constant voltage charging at the set voltage (“absorption”). The current will tail off as the battery’s charge state increases and the equivalent resistance rises. How long it stays in absorption can be based on how long it was in bulk charging (“adaptive absorption”), or a hard time limit, or a current level (expressed in percent of battery capacity on these chargers).

It then switches to float, which is also constant voltage charging, but potentially at a lower voltage than absorption depending on your setting. The current will be whatever the battery draws at that charger voltage.

The charger will reset and start bulk charging again when the battery voltage drops below a set level.

 

[Wallowa]

Ron,

No worries, I did not take your post as a wave-off.....Ask Vic, I am like the "Energizer Bunny" and I just keep going...

My Orion DC/DC does not have a bulk voltage setting...only Absorp and Float...BB says not to use the "adaptive" so I setting the charge times....

New Twist:

Just checked my 712, DC/DC, MPPT and BB....first thing I noticed was a 'green' steady light on Orion [means float charge is on], never saw that before....means it is on...and 'blue' was flashing to indicate Bluetooth... showing "Float" on DC/DC .....Victron Connect 712/BB showed a higher voltage in BB than yesterday by quite a bit...13.35 yesterday vs 13.88V Today...what? Tundra battery on Battery Tender and AGM battery showed 13.3V...disconnected fuse to DC/DC and green light out....noticed that I did not have the DC/DC disconnect set to "Smart Alternator" but to "User'; switched to "Smart" and Shutdown default settings appeared [14V 'start' and 'delayed' 13.3V @ 120sec with 'shutdown' 13.1v] and green light went out...with fuse closed and tender on.

Yesterday I had the Hawk out draining the water and ran the DC/DC..Solar to about 14.4V...on a long time...when I turned off the Tundra Ignition, the DC/DC recognized that and stopped any current to BB.

I will fiddle with this and see where it is going....in 15Mins today after shutting off the 'green' light BB from 13.88 to 13.83. Now 1 hour + and BB @ 13.73V.

Will let you folks know as the saga continues....

Phil

Ps...The DC/DC was set to "Charge" and not "Power" setting...

 

[Jon R]

Sorry, i wasn’t thinking it through when I wrote that. In bulk charging the voltage is limited to the absorption voltage setting. When the voltage in bulk charging rises to that set voltage it switches to absorption mode.

 

[Wallowa]

Sorry, i wasn’t thinking it through when I wrote that. In bulk charging the voltage is limited to the absorption voltage setting. When the voltage in bulk charging rises to that set voltage it switches to absorption mode.

Got that...so the voltage at the start is usually very close to absorp voltage setting, hence bulk full bore amperage output will be relatively brief...will pay closer attention to that cycle next time I start the Tundra...thanks.

All good...can say for certain my BB is at 100% whether I like it or not! Seems to have balanced and topped off.