First Charging and top balancing Lifepo4

[Delfin]

Originally Posted by Flod

Yes i realized that myself as well and changed the setup after a few hours. Then I stopped completely after the responses in this thread. I now understand that it was a bad idea to only have the small 5A charger. I was thinking that this is a onetime job and I’ll never do it again so let’s go with the cheapest possible charger.

Worth noting that the drop off of charge current for LFP is extremely abrupt, at least for my bank. I'm underway, and just finished charging using just the alternator putting out 97 amps to a 600 Ah bank. I've noted that the lower the charge current, the lower the voltage where the acceptance rate drops off a cliff. Today, once the bank reached 28 vdc the time to drop from 97 amps to under 30 was around 1 minute. If I were charging also with the genset at 200 amps or so, the drop off would not have occurred until the bank reached 28.3 - 28.6 vdc. I find this intriguing and wonder if other users (not theoreticians) have observed the same thing.

In any case, I still suspect that with you using the small capacity charger, the point where the bank's acceptance rate drops is quite low, voltage wise.

[Delfin]

Originally Posted by john61ct

From their manual



Attachment 192694

Ah, I see where you got the .5% as the sacred value. From Trojan's 1 - 3%. Very helpful.

[Montanan]

Originally Posted by Flod

Yes i realized that myself as well and changed the setup after a few hours. Then I stopped completely after the responses in this thread. I now understand that it was a bad idea to only have the small 5A charger. I was thinking that this is a onetime job and I’ll never do it again so let’s go with the cheapest possible charger.

Just be sure to wire your bank correctly for both the charging AND the discharging circuitry, one must balance the resistance of the batteries and the leads and terminal connections. That article reveals the implications of doing otherwise.

As to a charging cutoff voltage, no one really needs to go to "full charge" which voltage is a manufacturer suggested value intended to balance between reasonable energy density and reasonable cycle life expectancy. The "suggested" voltage can be over a range of voltages depending on the specific chemistry of the battery. It is not a hard data point, it is a targeted compromise value, one can go higher and increase energy density and capacity stored, but trade off as to its cycle life. Full is a self defined metric and definitely not an exact number. Kind of like the gauge on your tank, F and E are neither Full nor truly empty.

Ditto as to discharge cutoff voltage.

At our company, it is a simple matter for us to reprogram the BMS and / or a charger to derive the energy levels we wish to deploy in our tool batteries or our EV batteries.

I am not certain as to Tesla's battery pack present parameters as to their ever updating software downloads but originally the battery packs were stated to be set to have a cut off at about 20% above the minimum voltage for depth of discharge and about 80% of the maximum voltage for the chemistry, basically deriving a pack utilizing 60% of its theoretical energy values. These days I suspect they have broadened the range of charging and discharging voltages so as to extend their operating range.

[john61ct]

Originally Posted by Delfin

Today, once the bank reached 28 vdc the time to drop from 97 amps to under 30 was around 1 minute. If I were charging also with the genset at 200 amps or so, the drop off would not have occurred until the bank reached 28.3 - 28.6 vdc. I find this intriguing

The lower the current rate, the less voltage "bounceback", the closer loaded voltage is to "true" resting.

True both for charging and discharging.

This is why, as Cpt Pat expresses so vehemently, extremely low C-rates need cutoffs closer to the median. High C-rates can go more extreme in the shoulders more safely.

Said another way, just for charging: low current has a much lower V::SoC ratio, you can overcharge at well under 3.45V.

High currents you can go all the way to 3.55V and stop, and your SoC will still be farther short of 100% Full, reflected in the drop while resting.

[BrissyBrew]

Can somebody please help me with this, appears to be a big difference of opinions regarding charging.

I am about to install a DIY 400AH Winston (8S cell 24V) system. Charging devices:
Victron 100/50 Solar Charge controller (PV array 1300W)
Victron 3000/24v 70Amp inverter charger.
30A DC to DC charger (enerdrive DC to DC charger for the alternator)

First of all I read about low current 0.05C - 0.033% (for me looking at 20A or greater for a single cell or 8S). Which means my original idea for initial top balancing of using a 10Amp power supply is out, even on a single cell but in a paralleled bank totally out it would need 160Amp charger. I did see if I could hire one nope not in Brisbane.

So for initial top balance
Charge to 3.35V stop the charging process, let the cells rest for a few hours, and measure the terminal voltage. When the resting open-circuit cell voltage reaches 3.35 volts you are done. Stop there!.

I am thinking of using 70A charger in the multiplus to do the initial bulk charge at 8S terminate it lower then try topping up the cells individually. I just realise I am leaving cells at 100% SOC for a long time in this process which is a no no but like what's going to happen when I normally have them fully changer.

For normal operation
I can program the changers (also have a programable BMS for cell / secondary protection)
-Solar 1300W PV array but that is max in theory only, stop on voltage with no absorption? In theory sometimes it could be putting out more 20A, eg 50A that would I be better treating it is a larger current and have some absorption time (lower voltage)

30A DC to DC charger voltage with absorption time (at a lower voltage?)

Victron 70A inverter/charger absorption time (at a lower voltage?)

Your recommendations would be appreciated. I want to protect my investment in the battery bank.

Originally I thought I could do it by having voltage based termination and zero absorption rate, how I see a think to memory issues in lithium batteries. Totally confused.
I was thinking of setting the BMS cell protection to 3.55VPC for HV relay 2.8VPC for LV relay. Setting charging voltage for the pack slightly lower. Just not sure if I should put some absorption at lower voltage on my changing devices.

[mbartosch]

Welcome to CF, BrissyBrew!

Originally Posted by BrissyBrew

I am about to install a DIY 400AH Winston (8S cell 24V) system. Charging devices:
Victron 100/50 Solar Charge controller (PV array 1300W)
Victron 3000/24v 70Amp inverter charger.
30A DC to DC charger (enerdrive DC to DC charger for the alternator)

First of all I read about low current 0.05C - 0.033% (for me looking at 20A or greater for a single cell or 8S). Which means my original idea for initial top balancing of using a 10Amp power supply is out, even on a single cell but in a paralleled bank totally out it would need 160Amp charger. I did see if I could hire one nope not in Brisbane.

So for initial top balance
Charge to 3.35V stop the charging process, let the cells rest for a few hours, and measure the terminal voltage. When the resting open-circuit cell voltage reaches 3.35 volts you are done. Stop there!.

I am thinking of using 70A charger in the multiplus to do the initial bulk charge at 8S terminate it lower then try topping up the cells individually. I just realise I am leaving cells at 100% SOC for a long time in this process which is a no no but like what's going to happen when I normally have them fully changer.

I can understand your confusion.
Let me describe how I did this with our 400 Ah bank.

Big, Fat, Disclaimer: I am not saying this is a proper way of doing it, and I am not saying anybody should do the same. In hindsight, with now 4 years of active experience with the bank, having followed all related communication on this forum, and being an EE, I am still reasonably comfortable with my approach which worked well for me and proved to be sufficient for our installation. I know it is not optimal, but it did work.

And I know that several people will likely disagree with what I am saying here and probably diss me. By all means, listen to them (!) and make up your own mind. They may have a point, and I may have screwed up my bank (nothing happened, so far...). But note, however, that there may be guesswork and folklore involved in such discussion.

OK, at the time I built my bank I was not really aware of potential overcharging issues with low charging current. So I first charged the cells in parallel (16P) to 3.6 V, then arranged them in series (4P4S), discharged the pack to about 95 % using a resistor.

Then I performed manual top balancing of the 4P4S bank with a smaller 5 A lab supply set to 14.4 V (current limited). Yes, 5 A.

Obviously tapering charge current is useless with such fractional C charging. So what I did was actively monitor each cell voltage with a good volt meter and ignored charge current completely.

Watching each cell approach 3.6 V I used a 0.5 Ohm 25 W resistor and manually shunted away charging current from the cells with the highest cell voltage, trying to keep all cells below 3.6 V and getting them all to the same voltage level. This felt a bit like playing electrical whack-a-mole, but it worked well for me.
I repeated this process until all cells read the same voltage (3.6 V), then stopped charging.
Immediately discharged the pack to 65 %, dismantled and shipped the bank to the boat, rebuilt the pack there in identical configuration.

I measured the cell balance after 2 years while pushing for a 14.0 V pack voltage, and all cells were still in balance. No automatic balancing is done on my pack.

I performed two capacity tests over the years, both yielded 96 % (after charging to 3.45 V cell voltage and cutting off at 2.9 V). This result is good enough for me and in line with what I observed with brand new 18650 LiFePO4 cells which I recently tested on my bench at home.

Regarding your setup: You can probably use the Victron for bulk charging, they are programmable and can be configured to assist you in performing the balancing. You need to come up with a solution to the top balance yourself.

For normal operation
I can program the changers (also have a programable BMS for cell / secondary protection)
-Solar 1300W PV array but that is max in theory only, stop on voltage with no absorption? In theory sometimes it could be putting out more 20A, eg 50A that would I be better treating it is a larger current and have some absorption time (lower voltage)

30A DC to DC charger voltage with absorption time (at a lower voltage?)

Victron 70A inverter/charger absorption time (at a lower voltage?)

Your recommendations would be appreciated. I want to protect my investment in the battery bank.

Originally I thought I could do it by having voltage based termination and zero absorption rate, how I see a think to memory issues in lithium batteries. Totally confused.
I was thinking of setting the BMS cell protection to 3.55VPC for HV relay 2.8VPC for LV relay. Setting charging voltage for the pack slightly lower. Just not sure if I should put some absorption at lower voltage on my changing devices.

My opinion for set points:
- charging sources set to 13.8 V (you may find that you may have to fiddle with fine tuning the charging sources so a high current source like the alternator does not totally squelch solar charging, resulting in PV regulators going to float very early. I found that I had to set the setpoint of the PV regulator a tad higher than the alternator - which again goes against recommendations lately found on this forum. That's my take, I am not saying you should do the same, see above)
- zero or very small absorption time
- float is debatable. Some say no float, some set it to 13.2 - 13.3 V. I am in the latter camp for usability reasons. I watch the bank being used and have a brain, though.
- cell protection could be as high as 3.6 V IMO, you should not reach this with properly configured charging sources
- LVC I'd set to 2.9 V. Trigger an alarm 20 % SoC (based on a coulomb counter) and maybe on 3.0 V cell voltage. You will not have much time left if the 3.0 V alarm chimes, though, cell voltage is dropping rapidly after passing about 3.05 V

I have not yet seen any memory effect on my bank, I'd say don't worry about it.

[john61ct]

Originally Posted by BrissyBrew

I am about to install a DIY 400AH Winston (8S cell 24V) system.

To be clear, each cell is 400Ah, only one string, nothing paralleled, correct?

You could use a say 40A charge source,

A. get **each cell** to the same setpoint, slightly below your desired "maintenance Full" definition, much higher than what you would use for "normal cycling Full"

or even use the Winston definition.

Then

B. do them all in parallel until amps taper to (practically) nothing.

This is a (hopefully) very rarely performed procedure, so the extra stress involved holding such high SoC so much longer than you would usually want to, will not cause significant loss of lifetime cycles.




> Charge to 3.35V stop the charging process, let the cells rest for a few hours, and measure the terminal voltage. When the resting open-circuit cell voltage reaches 3.35 volts you are done. Stop there!

That would be fine, could do 3.34V as stage A above, then strive to get the whole bank to 3.35V **resting** in stage B all paralleled together.

In practice, once above say 3.345V paralleled, soon as the individual cells isolated and at rest - say two hours - are within 0.005V, or maybe 0.008V, you could then assemble the pack as serial.

The challenge then will be to ensure your charge termination algorithm at say 27.6V CV / Absorb keeps your normal charge cycling below that SoC point.


______

> I am thinking of using 70A charger in the multiplus to do the initial bulk charge at 8S terminate it lower then try topping up the cells individually.

That would be fine, prior to stage A above. Using 27.6V and holding Absorb / CV for say 10-15min will likely get you most of the way there.


You need to investigate - independently verify - how the BMS does its balancing.

Or just use it for protection only, just monitor the balance issue, keep your definition of "normal cycling Full" low enough may not need to re-do it even periodically.


IMO using 27.6V all the time is fine, as long as you are only going to your "normal cycling Full" when loads will soon be pulling the bank SoC back down, do not let them sit there for a large % of their life.


______

> Originally I thought I could do it by having voltage based termination and zero absorption rate, how I see a think to memory issues in lithium batteries.

I think that issue is overblown except when a single automated system is terminating charge at the exact same point every time.

Using a mix as we do in practice, almost every cycle will end at a slightly different "full" point.

If you are concerned, then as a regular maintenance protocol (analogous to equalizing a lead bank), bring your SoC up to a higher definition of 100%, your "maintenance Full" if you like as when top balancing above,

or even use the Winston definition

That will also be a good time (if you choose) to use your BMS for occasional active balancing, hold that high SoC for long enough to see if its (likely **very** low) balancing current has an impact on bringing the cells closer together.

But, again, only if you are concerned about this "memory effect" warranting that extra effort.

_____
> BMS cell protection to 3.55VPC for HV relay
I think fine. Consider lowering it a little at a time, if all your sources are reliably lower, but then you may need to raise it while doing the "maintenance Full" cycles.


> 2.8VPC for LV relay.
Too low IMO, unless heavy winching or something requires it.

For good longevity, if discharge C-rates are kept below say 0.3C (150-200A), I'd use at least 23.9V

And not as a functional LVC, use "user level" adjustable LVCs on circuits to set non-essential and/ or high-amp loads to even 3.2Vpc to buy time for safety / nav Essentials circuits.

[Q Xopa]

Originally Posted by john61ct

To be clear, each cell is 400Ah, only one string, nothing paralleled, correct?

You could use a say 40A charge source,

A. get **each cell** to the same setpoint, slightly below your desired "maintenance Full" definition, much higher than what you would use for "normal cycling Full"

or even use the Winston definition.

Then

B. do them all in parallel until amps taper to (practically) nothing.

This is a (hopefully) very rarely performed procedure, so the extra stress involved holding such high SoC so much longer than you would usually want to, will not cause significant loss of lifetime cycles.




> Charge to 3.35V stop the charging process, let the cells rest for a few hours, and measure the terminal voltage. When the resting open-circuit cell voltage reaches 3.35 volts you are done. Stop there!

That would be fine, could do 3.34V as stage A above, then strive to get the whole bank to 3.35V **resting** in stage B all paralleled together.

In practice, once above say 3.345V paralleled, soon as the individual cells isolated and at rest - say two hours - are within 0.005V, or maybe 0.008V, you could then assemble the pack as serial.

The challenge then will be to ensure your charge termination algorithm at say 27.6V CV / Absorb keeps your normal charge cycling below that SoC point.


______

> I am thinking of using 70A charger in the multiplus to do the initial bulk charge at 8S terminate it lower then try topping up the cells individually.

That would be fine, prior to stage A above. Using 27.6V and holding Absorb / CV for say 10-15min will likely get you most of the way there.


You need to investigate - independently verify - how the BMS does its balancing.

Or just use it for protection only, just monitor the balance issue, keep your definition of "normal cycling Full" low enough may not need to re-do it even periodically.


IMO using 27.6V all the time is fine, as long as you are only going to your "normal cycling Full" when loads will soon be pulling the bank SoC back down, do not let them sit there for a large % of their life.


______

> Originally I thought I could do it by having voltage based termination and zero absorption rate, how I see a think to memory issues in lithium batteries.

I think that issue is overblown except when a single automated system is terminating charge at the exact same point every time.

Using a mix as we do in practice, almost every cycle will end at a slightly different "full" point.

If you are concerned, then as a regular maintenance protocol (analogous to equalizing a lead bank), bring your SoC up to a higher definition of 100%, your "maintenance Full" if you like as when top balancing above,

or even use the Winston definition

That will also be a good time (if you choose) to use your BMS for occasional active balancing, hold that high SoC for long enough to see if its (likely **very** low) balancing current has an impact on bringing the cells closer together.

But, again, only if you are concerned about this "memory effect" warranting that extra effort.

_____
> BMS cell protection to 3.55VPC for HV relay
I think fine. Consider lowering it a little at a time, if all your sources are reliably lower, but then you may need to raise it while doing the "maintenance Full" cycles.


> 2.8VPC for LV relay.
Too low IMO, unless heavy winching or something requires it.

For good longevity, if discharge C-rates are kept below say 0.3C (150-200A), I'd use at least 23.9V

And not as a functional LVC, use "user level" adjustable LVCs on circuits to set non-essential and/ or high-amp loads to even 3.2Vpc to buy time for safety / nav Essentials circuits.

From what little I know, this all sounds reasonably sound. It sounds like what most of the well respected users and professionals are doing.

So how do you know all this? What are your Bona fides?

One question, when you say "Using a mix as we do in practise". Can you elaborate on your practise?

Or is that more of a metophoric 'we'?

[BrissyBrew]

Thank you for the replies.
Confession:I hope I don't get booted from the forum but the battery bank is for Motorhome/Land yacht. People on this board are way more knowledgable than the RV forums which I find a little more wild west and less professional input.

Clarifications:
The cells are Winston each single cell @ 400AH, in which I using 8 cells in series for a nominal 24V pack.

Changes:
3.0V as LV relay set point as suggested.

System setup:
Zeva BMS (it has some active balancing but really only resistor shunts I think way too small to make much difference on a 400AH cell) actually the BMS I can turn balancing on and off. Does have cell monitoring display 0.005 resolution.

Dual Bus: I plan to implement a dual bus system so in the advent that charging is disconnected loads are still connected to drain SOC, or if LV relay is tripped loads are disconnected and charging is still possible. Exception to the rule is the inverter/charger is going to be on the load side of the bus. I am looking at putting a secondary relay in and driving the victron inverter/charger disconnect off the HV relay, but dont plan to be plugged into shore power that often

Usage:
AC off the inverter are my high current consumers, induction cooker, hot water (it is also a heat exchanger unit), air con (split cycle inverter 400-1200W), inverter fridge running 24/7.
DC stuff is pretty low draw stuff a couple computer fans 24/7 LED lights, extraction fans.

Given possible memory effects?
Do I need to worry about shallow cycling, like reach full charge charging stops, current draw runs it down soon starts charging and tops up quickly. Solar charge controller and constant loads being the culprit.


Currently thinking of using the 10A Power supply to do initial charging until cells hold 3.35V. Then topping off any cells that need the extra juice.

[Montanan]

Originally Posted by BrissyBrew

Thank you for the replies.
Confession:I hope I don't get booted from the forum but the battery bank is for Motorhome/Land yacht. People on this board are way more knowledgable than the RV forums which I find a little more wild west and less professional input.

One can cruise & sail on water, ice or land. Welcome aboard the forum.

Most all of the forum members are proud owners of RVs.

Recreational Vessels.

Land sailing, also known as 'sand yachting', 'land yachting' or 'dirtboating'.

[rvlandlubber]

Its definitely worth spending the extra time to get your initial balance correct.
One thing to be aware of is that the cell voltage imbalance is only observable at cell votages above around 3.5v.
To test how well your initial balancing has gone, I would assemble the pack and use the zeva cell monitoring to monitor the cell voltage differences during a charge cycle. (disable its balancing function first).
For the purposes of the test 28.8v (3.6v/ cell).
I would be happy with anything less than 50mV cell difference.

[john61ct]

Originally Posted by BrissyBrew

Zeva BMS (it has some active balancing but really only resistor shunts I think way too small to make much difference on a 400AH cell)

Just use the per-cell monitoring.

If you use below-the-shoulder top voltages for normal cycling

no need to turn balancing off, in effect disabled anyway


they may never need rebalancing, or at least for years.

But watch, frequently / closely at first.

> Given possible memory effects?

Already fully addressed above.


> Do I need to worry about shallow cycling, like reach full charge charging stops, current draw runs it down soon starts charging and tops up quickly. Solar charge controller and constant loads being the culprit.

Yes, when you only need to cycle say 10% of capacity or less, better for longevity to do so in the lower SoC ranges rather than always going to Full.

Again, repeat after me, sitting at Full is stressful, to be avoided!

IOW only go to Full **when you need to**. In that scenario, when you see it won't be sunny, or unusually big / long loads will be needed shortly.

Now, that's coming from IMO gaining extra bank longevity is worth going to some trouble.

Given the bank may last decades anyway, others say fuggedaboudit who cares.

Your rig, your choice.




> Currently thinking of using the 10A Power supply to do initial charging until cells hold 3.35V. Then topping off any cells that need the extra juice

covered above, but do both stage A & B above as well, not done until isolated and resting cells V are precisely balanced

[senormechanico]

Originally Posted by mbartosch

Welcome to CF, BrissyBrew!



I can understand your confusion.
Let me describe how I did this with our 400 Ah bank.

Big, Fat, Disclaimer: I am not saying this is a proper way of doing it, and I am not saying anybody should do the same. In hindsight, with now 4 years of active experience with the bank, having followed all related communication on this forum, and being an EE, I am still reasonably comfortable with my approach which worked well for me and proved to be sufficient for our installation. I know it is not optimal, but it did work.

And I know that several people will likely disagree with what I am saying here and probably diss me. By all means, listen to them (!) and make up your own mind. They may have a point, and I may have screwed up my bank (nothing happened, so far...). But note, however, that there may be guesswork and folklore involved in such discussion.

OK, at the time I built my bank I was not really aware of potential overcharging issues with low charging current. So I first charged the cells in parallel (16P) to 3.6 V, then arranged them in series (4P4S), discharged the pack to about 95 % using a resistor.

Then I performed manual top balancing of the 4P4S bank with a smaller 5 A lab supply set to 14.4 V (current limited). Yes, 5 A.

Obviously tapering charge current is useless with such fractional C charging. So what I did was actively monitor each cell voltage with a good volt meter and ignored charge current completely.

Watching each cell approach 3.6 V I used a 0.5 Ohm 25 W resistor and manually shunted away charging current from the cells with the highest cell voltage, trying to keep all cells below 3.6 V and getting them all to the same voltage level. This felt a bit like playing electrical whack-a-mole, but it worked well for me.
I repeated this process until all cells read the same voltage (3.6 V), then stopped charging.
Immediately discharged the pack to 65 %, dismantled and shipped the bank to the boat, rebuilt the pack there in identical configuration.

I measured the cell balance after 2 years while pushing for a 14.0 V pack voltage, and all cells were still in balance. No automatic balancing is done on my pack.

I performed two capacity tests over the years, both yielded 96 % (after charging to 3.45 V cell voltage and cutting off at 2.9 V). This result is good enough for me and in line with what I observed with brand new 18650 LiFePO4 cells which I recently tested on my bench at home.

Regarding your setup: You can probably use the Victron for bulk charging, they are programmable and can be configured to assist you in performing the balancing. You need to come up with a solution to the top balance yourself.




My opinion for set points:
- charging sources set to 13.8 V (you may find that you may have to fiddle with fine tuning the charging sources so a high current source like the alternator does not totally squelch solar charging, resulting in PV regulators going to float very early. I found that I had to set the setpoint of the PV regulator a tad higher than the alternator - which again goes against recommendations lately found on this forum. That's my take, I am not saying you should do the same, see above)
- zero or very small absorption time
- float is debatable. Some say no float, some set it to 13.2 - 13.3 V. I am in the latter camp for usability reasons. I watch the bank being used and have a brain, though.
- cell protection could be as high as 3.6 V IMO, you should not reach this with properly configured charging sources
- LVC I'd set to 2.9 V. Trigger an alarm 20 % SoC (based on a coulomb counter) and maybe on 3.0 V cell voltage. You will not have much time left if the 3.0 V alarm chimes, though, cell voltage is dropping rapidly after passing about 3.05 V

I have not yet seen any memory effect on my bank, I'd say don't worry about it.

I could have written this same post, except I did it with a 200 aH bank.
I also did more or less the same thing with a 700 aH, 24 volt bank for our home's grid tie.
The boat's cells were HiPower, purchased in (I think) 2012. They are still perfect as the day they were installed.
I purchased them "used for testing" from Witzgall, another poster on CF.
I love these cells !
The house grid tie has Winston 700 aH cells, purchased from Balqon who has since gone out of business. They are doing nicely, although a couple of cells are a bit "better" than the rest. Higher voltage by about 0.02 but barely.
I have no problem with any of them.

I purchased 700 aH at the time for the price of 400 so a happy camper.
I have come to the conclusion that the "delicate" nature of charging LiFePo4 is over emphasized. If anyone wants to show me I am mistaken, I'm willing to help, but so far I think it's a red herring.
I set my fixed voltage adjustable alternator to 13.7 the Bluesky 2512iX mppt to 13.8 and float to 13.2-13.4 depending on if I'm aboard or not and LIFE IS GOOD....




Oh and an aside, cell voltages only REALLY diverge above about 3.5 and below 3.0.


John, why don't you advice, instead of all your internet readings and theory?
Of course, as all readers of this and other LiFePo4 threads will notice from john61ct, <<CRICKETS>>

[john61ct]

Originally Posted by senormechanico

I have come to the conclusion that the "delicate" nature of charging LiFePo4 is over emphasized. If anyone wants to show me I am mistaken, I'm willing to help, but so far I think it's a red herring.
I set my fixed voltage adjustable alternator to 13.7 the Bluesky 2512iX mppt to 13.8 and float to 13.2-13.4 depending on if I'm aboard or not and LIFE IS GOOD....[emoji2]

That is all good, no one is saying anything's "delicate".

But for those with say a stock alt pumping 14.4V, having drunk the "drop-in koolaid", need to be educated that doing so will lose a lot of lifetime cycles.

Those actually reading these threads do already understand those big issues, only finer points are still getting debated anymore.

chirp chirp

[nebster]

Originally Posted by BrissyBrew

Dual Bus: I plan to implement a dual bus system so in the advent that charging is disconnected loads are still connected to drain SOC, or if LV relay is tripped loads are disconnected and charging is still possible. Exception to the rule is the inverter/charger is going to be on the load side of the bus. I am looking at putting a secondary relay in and driving the victron inverter/charger disconnect off the HV relay, but dont plan to be plugged into shore power that often

Do you plan to have a generator as well?