Which Charge profile is ok for LifePo4?

[John Frum]

After reading all manner of opinions on charge profiles is the following profile provided from this charger dongle the ideal for LPF?
https://www.iotaengineering.com/pro...ls-to-use-with-lithium-ion-batteries-with-bms

Where is the charge profile described?

 

[John Frum]

I found this

https://www.donrowe.com/v/vspfiles/pdf/iq-lifepo_owners_guide.pdf

Bulk is 3.675 volts which is out of spec high for lifepo4 which should be maximum 3.65 volts.
I'm guessing that there is no real absorption(constant voltage) phase.
Float is 3.4 volts which is ok.

Its far from optimal IMHO.
I worry that you will trip your bms on cell over voltage.
I would only use it you already have the converter/charger and don't want to spend money on a proper solution.
An quality inverter/charger will have a configurable charge profile is the way to go.

 

[Ampster]

......is the following profile provided from this charger dongle the ideal for LPF?

I could not tell what the values were for Constant Current and Constant Voltage so I would say it is not ideal. @smoothJoey was able to find more details and we reached similar conclusions.

Furthermore it mentioned trickle charge and under certain cercumstances trickle charging (also called Float) can be detrimental to Lithium batteries. I do agree with @smoothJoey , that a Float voltage of 3.4 might be okay under the right circumstances. It is a higher value than I would use however. More details would be needed. Also this device is apoarently designed to work with only specific models and one brand of charger so the details of those two components working as a system would need to be known.

 

[jbird526]

Where is the charge profile described?

Sorry, was sidelined and only just got back to the forums again.

Was going to provide the specs from Don Rowe but you beat me to it. I find it confusing how, assuming engineers are creating these solutions, that they are not within spec for LFP charging.

Thank you @smoothJoey and @Ampster for the follow up on my initial question.

So who makes the "perfect" inverter/charger and standalone charger for LFP? And here come the 10,000 opinions.....

Just kidding I really do appreciate all the opinions and information that are provided on the forums.

Do I just buy a Victron or Samlex and sleep well at night, not having to think again if they are kicking into bulk, absorption or float at the exact right voltage?

 

[John Frum]

Sorry, was sidelined and only just got back to the forums again.

Was going to provide the specs from Don Rowe but you beat me to it. I find it confusing how, assuming engineers are creating these solutions, that they are not within spec for LFP charging.

My guess is that there is no absorb mode so the engineers guessed that being 100mv over spec would just compensate for the path resistance between the battery and the charger.
They are probably also designing for Battleborn batteries or similar which I would guess are matched cells that not available to the diy crowd at prices that we would find attractive.

Thank you @smoothJoey and @Ampster for the follow up on my initial question.

So who makes the "perfect" inverter/charger and standalone charger for LFP? And here come the 10,000 opinions.....

Just kidding I really do appreciate all the opinions and information that are provided on the forums.

Do I just buy a Victron or Samlex and sleep well at night, not having to think again if they are kicking into bulk, absorption or float at the exact right voltage?

Perfect depends on the environment and the use case.
That is why its good to have configurabillity.
BTW I am using a powermax converter/charger which is a direct competitor to your iota.
I chose it because the converter/chagers are relatively inexpensive and have a reputation for being tough as nails.
The surprise for me was how loud the fans are.
Sales guy warned me but I've got the hearing on an aging roadie so I thought it wouldn't matter.
Thing howls like there is a full moon.

 

[jbird526]

They are probably also designing for Battleborn batteries or similar which I would guess are matched cells that not available to the diy crowd at prices that we would find attractive.

You are correct, was not posing the question specific to what "most" are probably doing here. What is the best profile and voltages for packs consisting of Eve or Lishen cells? The devil is truly in the details when it comes to tenths of volts. What inverter/chargers or just chargers can provide those? Maybe a sticky for those that can be agreed upon would be helpful? I defer to others in my ignorance.

 

[John Frum]

You are correct, was not posing the question specific to what "most" are probably doing here. What is the best profile and voltages for packs consisting of Eve or Lishen cells? The devil is truly in the details when it comes to tenths of volts. What inverter/chargers or just chargers can provide those? Maybe a sticky for those that can be agreed upon would be helpful? I defer to others in my ignorance.

Most of the digital configuration options are down to 100mv.
The bigger devil is in the use case.
As I see it there are 3 dimensions to the problem.
1=time
2=charge voltage
3=current
Its my understanding that the Goldilocks zone of charge current is .2c to .5c.
And for 100% SOC its between 3.45 and 3.65 volts per cells.
Too low of current and the SEI layer absorbs lithium that will then not be available to the chemistry.
As current increases so does the calendar aging intrinsic to the chemistry as expressed by heat.
Voltage stress increases with voltage but the charge cycle time duration decreases as voltage increases.
In other words there is a time component to all the stressors to a battery whether they are necessary or avoidable.
Finally a battery ages even if its not used.