15 replies to this topic

[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.

Edited by Jon R, 09 October 2021 - 04:26 PM.

[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

Edited by Wallowa, 09 October 2021 - 04:54 PM.

[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! 

Edited by Wallowa, 09 October 2021 - 11:24 PM.

[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