Lishen, EVE, Basen 280AH: Which values/parameter do you use for MPPT/DC2DC

[CaptainRivet]

Hi Lishen,EVE,Basen 272/280 AH users,

What values/parameters do you use in your MPPT, DC2DC and end of charge voltage BMS?
There cells are basically identical as proven by so many threads and data sheets and are a very common choice if you wanna have max AH for the buck.There are a lot parameters/values around for home storage/offgrid or RV use that are proven to work well but rarely any on boats. Boat usage is very different to offgrid/home storage or RV, so which Parameter/values worked well for you for MPPT, DC2DC (or regulated alt) and end of charge voltage.

If you could state your bank size and solar size that would be helpful too.

[markcouz]

I use 3.45v per cell in series.

The amount of energy available between 3.45v and 3.65v which is often regarded as 100% SOC is very little so I am not sacrificing much.

By leaving some headroom it allows my active balancer plenty time to top balance on a daily basis while the bank is sitting in float (usually around 12.30/1pm).

[markcouz]

...200Ah 48v and 400Ah 12v.

[markcouz]

... 2.2kw

(apologies, it appears that my reading comprehension is failing!)

[hjohnson]

I let my BMS run the whole thing.

It’s configured to go to 3.65v/cell for a brief period, if the SoC has dropped below 80% or it’s been more than a week since the last time that high, and then backs off to 3.45v/cell if the cells are all in balance. Typically it’s only at 3.65v for less than a few minutes, before it backs down the knee to 3.45v.

It will then hold that 3.45v until the next cycle

[lmxr]

All chargers are set to 14.0 V absorption, except for the mains charger, which delivers 14.1 V (can't be modified). The BMS measures the battery (tail) current and turns the chargers off when it thinks they are full similar to described in https://nordkyndesign.com/charging-m...battery-banks/.

Bank: 840 Ah
PV: 400 Wp
Alternator: 55 A continuous

[Statistical]

3.45V per cell bulk/absorb voltage (so 13.8V for "12V" battery). Anything higher charges faster but doesn't increase capacity and puts more stress on the battery.

If you don't believe it charge at 3.65V then once fully charged disconnect all charging sources and loads and wait at least 8 hours but ideally 24. Voltage will be back down to 3.4V per cell. That is the resting voltage at full SoC for LFP. Anything higher is simply temporary surface charge.

[wholybee]

I don't see any reason the selected voltages should be any different than other brands (Winston, Calb, Sino). If you have settings for those, you can use them with the Lishen/EVE/ Basen and that will be fine. People use voltages that are all over the place for various reasons, but as long as you don't overcharge them and provide a way for them to stay in balance, it isn't going to make much of a difference.

Charge to between 3.45Vpc and 3.65Vpc. At 3.65Vpc use no absorption time. At 3.45Vpc use about 10-20 minutes per 100Ah. Charging to 3.65V gets them to 100% the fastest, charging to 3.45Vpc takes longer but provides more time to balance and arguably provides a longer cell life.

If your cells will stay in balance without balancing every cycle, then you can charge to even lower than 3.45V, or omit the absorption cycle. But you still should still occasionally charge to 3.45Vpc+ to check them.

As soon as 100% is reached from above, start the discharge cycle. Don't let the cells sit at 100%

[Simi 60]

Originally Posted by CaptainRivet

. Boat usage is very different to offgrid/home storage

Ours is pretty much identical to off grid home usage as our boat is our off grid home.
The batteries don't know or care that the home is floating

As such, I took my advice on building our batts and setting the charge parameters from a guy walking the walk AND talking the talk, living off grid, with essentially the same battery, mppt and inverter charger as ours.
And the spec sheets and parameters he linked to from the manufacturers

https://diysolarforum.com/members/st...720/#resources

The Genset/charger is and dc2dc chargers will be set to slightly lower settings letting solar do the finish.

This is on a 840ah @ 24v EVE 280k batt
2.5kw of solar with midnite classic 150 mppt controller
Victron multiplus 5000/120 inverter charger
70amp (2x sterling 35amp @ 24v) dc2dc on a 105 amp 36si alternator

[tanglewood]

Originally Posted by hjohnson

I let my BMS run the whole thing.

It’s configured to go to 3.65v/cell for a brief period, if the SoC has dropped below 80% or it’s been more than a week since the last time that high, and then backs off to 3.45v/cell if the cells are all in balance. Typically it’s only at 3.65v for less than a few minutes, before it backs down the knee to 3.45v.

It will then hold that 3.45v until the next cycle

What BMS? That seems very high. Most cells don't want more than 3.6V, and most people try to stay distinctly below that.

[tanglewood]

Originally Posted by CaptainRivet

There are a lot parameters/values around for home storage/offgrid or RV use that are proven to work well but rarely any on boats. Boat usage is very different to offgrid/home storage or RV, so which Parameter/values worked well for you for MPPT, DC2DC (or regulated alt) and end of charge voltage.

How is boat use different from off-grid or RV, and how does that impact charge parameters?

[hjohnson]

Originally Posted by tanglewood

What BMS? That seems very high. Most cells don't want more than 3.6V, and most people try to stay distinctly below that.

It’s a REC ABMS. I can program/configure it for whatever voltage thresholds I want. The battery lives most of its life between 13.2v and 13.6v. It only hits the 14.5v very briefly (minutes) before dropping back to 13.9. The only time it stayed high for any meaningful period of time was on the initial charge up of my bank as it balanced out the cells.

These numbers are all set as per the battery data sheet. After 18 months, the battery is still balanced to within 0.005V.

[CaptainRivet]

Originally Posted by tanglewood

How is boat use different from off-grid or RV, and how does that impact charge parameters?

First and main difference: if you are totally out of power offgrid/RV you sit in the dark and pull out a candle and read a book, nothing happens.

On a boat: it can sink because exactly then a seacock or a hose breaks. You draging to shore and cannot pull up the anchor...and a lot more situations like this where you need power to simply survive.

Offgrid is in general very overpaneled as you have simply enough space for plenty of solar panels but bank is small in comparison so they charge with 0.5C or more. Discharge is typically 0.2-0.3C.
Boat every relative shade free centimeter is premium, so you have small amout of panels but a big bank in comparison, C-rate charge is typically 0.05 till 0.2C, discharge even lower with some peaks to 0.3C when you cook via inverter or AC powering up.
Due to this offgrid cycles the bank deeper and more often while a boat its less deep and many more microcycles.

Offgrid you have one charge source solar and sometimes a gen.
a boat has plenty: solar, alternators, windgen, aquagen, generator

Offgrid you have a fixed and stable location where you can optimize your whole system to the given parameters and surrounding.
Boat is unstable, rocking around and constantly changing location means everything is changing constantly.

And all this leads to different charge parameters to fit the setup and situation.
On a boat i wanna have the bank charged with max speed, i don't know what the next day brings...
But charging with 0.05-0.1C is basically extremly slow charging comparable to absorbtion phase (read the Nordkyn article linked above in the other post) in regards of eg overcharging in absorption.
On the other side if i have bad weather on passage the alternators pumping in constantly amps in over days 24/7 or if you are a motoryacht.

So yes i need charge paramters that take that all into account and thats why i was asking which parameters do you use.
And not only the end of charge voltage but also the parameter in all your charge sources like MPPT, DC2DC or regulator.

Also cells from different manufacturers have in theory the same lifepo4 chemistry but build different internally and to different specs.
So they have a slightly different behaviour which you can easly see on the topics in the DIY solarforums and others.
Eg Winston need from time to time a 3,65V charge or they get out of balance, yes an active balancer can cover this up but if you have only passive balancing thats what will happen.

EVE, Basen, Lishen on the other side don't like high voltages and start to bulge if you do, my buddy that has the NPO building powerwalls and EVs recommend not to go over 3,55V end of charge due to this.
So you have a lot of moving targets to shoot at and one side is the theory that eg statistical brought up and the other side is what you use and worked well for you on your boat.