Setting Charge Profiles for Lithium - Help

[UFO]

I am in the process of upgrading to a lithium bank and looking at both of my MPPT controllers (yet to get to the Mastervolt charger) there are a LOT of settings that can be set and predictably the Victron has Different settings to the Renogy.


I have attached screen grabs of both MPPT settings screen as well as the data sheet for the batteries I will be getting.


I will be getting a marine electrician to help me with the install, but I want to get my head around the settings and what they should be set at, so input from those who know would be appreciated.

[donradcliffe]

Equalization is a lithium battery killer, so set the equalization voltage as low as it will let you and the equalization time to zero, IN ADDITION to telling the controllers not to equalize. The jury is still out, but I set my boost/bulk/absorption voltages to 14.1, and others recommend 13.8. Float recommendations that I have seen are 13.4 to 13.6.

[UFO]

There quite a few others settings on there as well anyone any idea about any of these?


Things like:


Absorption Duration

Maximum Absorption Time
Tail Current
Boost Charge Return V


and quite a few more.....

[smac999]

absorption time is 0 for lithium. duration and max


also turn off the temp compensation.

[T1 Terry]

I generally set chargers without battery voltage sensing to 14v bulk/absorption if the cable from charger to battery is heavy gauge and short, 14.1v if the cable is borderline or the cable run is long. If you have votage sensing on the charge controller, then 13.9v for bulk/absorption. Float I set at 13.7v for a system in full time use, 13.6v to 13.4v for a system not regularly used.
Absorption time should be set at "fixed" if that is available and 20 mins max if you have a reasonable capacity battery, 400Ah or bigger. Tail current usually a percentage figure, 1% of a 400Ah battery is 4 amps and this is the point the charger switches from absorption mode to float mode. The aim is to have the battery drop into float mode before any cell starts to suffer voltage run away from the 3.45v - 3.5v mark to the 3.6v mark and the charge cut being triggered.
If your BMS doesn't have cell voltage monitoring and high cell/low cell voltage cut .... good luck with getting a long cycle life ..... but set everything at a very conservative level, 13.6v end of charge and 12v load isolate .... You won't get the full capacity with those settings but you will at least still have a battery with reasonable capacity after 5 yrs.
Basically, if you don't still have the full advertised capacity measured at the manufacturers amps load after 10 yrs full time use, either you bought poor quality batteries or you have a poor quality BMS system.

T1 Terry

[T1 Terry]

Missed one, boost voltage return .... generally used for batteries that sit unused for long periods so it can be set low at around 13v, but really the charger should still be able to put out the full capacity even at the lower float voltage so this should never be triggered unless a long spell of poor weather has lept the solar harvest low.
Things like a Victron BMV need the battery to return to fully charged every so often to calibrate the true 100% SOC point because this can wander out of spec with very small current drains and the small drain of the BMS itself .... strangely enough, the Victron BMV can't actually measure the BMS and the BMV drain, it is only a trickle and "noise" on the circuitry of any active system can be seen as a discharge or charge current by the BMV if the min charge/discharge current is set too low

T1 Terry

[UFO]

Originally Posted by T1 Terry

I generally set chargers without battery voltage sensing to 14v bulk/absorption if the cable from charger to battery is heavy gauge and short, 14.1v if the cable is borderline or the cable run is long. If you have votage sensing on the charge controller, then 13.9v for bulk/absorption. Float I set at 13.7v for a system in full time use, 13.6v to 13.4v for a system not regularly used.
Absorption time should be set at "fixed" if that is available and 20 mins max if you have a reasonable capacity battery, 400Ah or bigger. Tail current usually a percentage figure, 1% of a 400Ah battery is 4 amps and this is the point the charger switches from absorption mode to float mode. The aim is to have the battery drop into float mode before any cell starts to suffer voltage run away from the 3.45v - 3.5v mark to the 3.6v mark and the charge cut being triggered.
If your BMS doesn't have cell voltage monitoring and high cell/low cell voltage cut .... good luck with getting a long cycle life ..... but set everything at a very conservative level, 13.6v end of charge and 12v load isolate .... You won't get the full capacity with those settings but you will at least still have a battery with reasonable capacity after 5 yrs.
Basically, if you don't still have the full advertised capacity measured at the manufacturers amps load after 10 yrs full time use, either you bought poor quality batteries or you have a poor quality BMS system.

T1 Terry

Thanks Terry


BMS will be



https://123electric.eu/products/123smartbms-gen3/


Pretty certain it will look after my batteries for me


The bank will be 1120Ah - 1% for tail current is 11.2 amps which seems pretty high??

[T1 Terry]

Originally Posted by UFO

Thanks Terry


BMS will be



https://123electric.eu/products/123smartbms-gen3/


Pretty certain it will look after my batteries for me


The bank will be 1120Ah - 1% for tail current is 11.2 amps which seems pretty high??

Quite a neat looking BMS system, I'll have to get a few to do beta testing on various capacity and battery voltage systems.
Set the top of charge voltage to 3.6v in any one cells and the system load cut to 2.8v in any cell.
Why such a big capacity battery? I'm not sure if you can set the charging down far enough but even 0.5% would have shift to float voltage at 5.5 amps and that really is trickle charging in such a high capacity battery.

I'm hoping you have built the battery with cells in parallel to build capacity and those groups in series to build voltage .... what voltage battery have you built?

T1 Terry

[UFO]

Originally Posted by T1 Terry

Quite a neat looking BMS system, I'll have to get a few to do beta testing on various capacity and battery voltage systems.
Set the top of charge voltage to 3.6v in any one cells and the system load cut to 2.8v in any cell.
Why such a big capacity battery? I'm not sure if you can set the charging down far enough but even 0.5% would have shift to float voltage at 5.5 amps and that really is trickle charging in such a high capacity battery.

I'm hoping you have built the battery with cells in parallel to build capacity and those groups in series to build voltage .... what voltage battery have you built?

T1 Terry

Thanks Again


Maybe 1% 11 amps will be OK, Just seemed rather large at first to me.



Yes it will be Built 4P4S with 280Ah cells - 12V.


Its big as I have a family of 4 and we will be living on the boat. I also want to be able to run my hot water heater (pulls 135Amps at 12v) for an hour a day without the generator. I will also heat water via the Generator when I am making water, but that may not be everyday.


I'll have to see how the 1KW of Solar goes, hopefully as I will be running the Genny to make water it will be enough.

[T1 Terry]

Are yes, trying to convince the kids that electrical energy is a limited resource is a battle you just can't win .... they remain kids until they move out and have to pay the power bills themselves, then things change :lol:

Installed an 1200Ah @ 24v system for an off grid house and 10kW of solar ..... the kid managed to flatten the battery over night by turning the swampy air cooling on full blast and going to bed with every thing imaginable turned on ... possibly to prove it could be done, who knows :lol: Learned the hard way, no coffee or breakfast, internet, TV, games consuls .... nothing until I told him how to reset the system and then had to wait for the solar to get the battery back up enough to hold the system on when he turned everything back on again :lol:

T1 Terry