System redesign to drop in LFP

[donradcliffe]

Originally Posted by rgleason

I think the problem with directly paralleling LFP with FLA is that they are different chemistries and if the FLA develops a short there is an instant meltdown including all the power from the LFP!

Having experienced a FLA battery with a shorted cell in a large FLA bank, I have to take issue with your "instant meltdown" scenario. If a cell shorts to zero volts, what really happens is that the remaining 5 cells in that battery operate at a higher voltage. If you have a LFP bank paralleled at say 13.5 volts, the cell voltage is 2.7V and the cells will outgas, but the entire battery doesn't go short circuit. It is more like if goes into equalization mode. The shorted cell is going to get warm, but you have hours, not milliseconds, to deal with the problem.

[rgleason]

Sometime ago a sailor who designed a system for himself using Precision Smart Fet's (I will remember the website eventually) working with a company that had programmable FETs to build his system that had 3 different smart FET's for a complete BMS for LFP.

Battleborn is rebranding these Precision Fets (with their own programming settings) and selling them for their battery systems:

• LiFePO4 Battery Isolation Manager (BIM) They utilize only voltage I believe, and the settings are specifically for Battleborn Batteries. Depending on respective voltages, they connect the starter and house batteries for a period of time and then disconnect. $172 I do not know if they comply with ABYC.
• Battery Guardian AutoSelect (BGA) $172 Protects battery from draindown.
• Battleborn has diagrams for these devices. I have not studied the system and do not know how it works, but I believe it is similar to the Sailor's system above from years ago.

Battleborn video at "The Basics of Lithium Battery Power for Sailboats and Other Marine Applications | Marine 101" at 19:04 Alternator Charging 101
This kind useless video simply states that you need to protect your alternator from a BMS disconnect, suggesting use of the Wakespeed, or alternatively a DC-DC charger. They avoid the issue of communications from the LFP battery needed for the external regulator. I find the Battleborn solution to be expensive for what it does (or rather what it doesn't do).

[rgleason]

The boat was Mai Tai and the 3 smart programmable Mosfets were by Perfect Switch in California. They are different than the ones above.


PS: Don, I would prefer to wait and see what the pros say.

[TxCoastSailor]

Originally Posted by phantomracer

That's what I was thinking. However, talking to Balmar tech support, they mentioned it is possible, if the LFP batteries are fully charged, that during initial bulk charge on start up, which is a min of 6 minutes, could be enough to trip the BMS on occasion, even if programmed properly.

Sounds to me like you need a different alternator regulator. Try the Wakespeed 500.

[hjohnson]

Originally Posted by TxCoastSailor

Sounds to me like you need a different alternator regulator. Try the Wakespeed 500.

Something like the WS500 is only really advantageous when you have a BMS that can communicate and integrate with it. This is what I have on my boat and it’s great. But it realistically doesn’t give you nearly as much if you’re using the usual dumb self contained drop-ins.

[more]

o my good again.
LIFEPO4 battery some have BMS and if you pick good quality BMS like
JK SMART BMS 4S 5S 6S 7S 8S 12V 24V BATTERY WITH 2A ACTIVE BALANCE
https://www.aliexpress.com/item/1005...8daUSjvUY&mp=1

or similar he triggered cut off only charging when is programed disbalance between cell.discharging still work.

second your alternator connect to battery separator first charging starter battery like main and second port is for service battery.

if battery BMS trigger disconnect something is wrong with battery.

and buy proper battery cell like winston. i still use after 5 year in charter winston cell 200Ah without BMS. but 200AH EVA CEll have BMS because this is lower quality battery. i pay 200 ah 12v 250$ bms 100$ but still after 3 years working good

but i have this JK BMS 48v and this is excellent BMS.

[more]

Originally Posted by CarlF

With my two years using KiloVault drop-ins I have never come close to a BMS shutdown because I am conservative about the voltage settings and charging and discharge amos

1. Kilovault specs a low 14.1v absorption charge. This is far below the level that would shut down the BMS. A advantage of the Kilovault BMS is that it does cell balancing at 14.0v so there’s no reason to ever go to 14.4v. The battery delivers the full rated AH at 14.1 voltage. But only my Victron solar charge controllers are set to 14.1 as they can be set to zero absorption time.

2. The alternator regulator is set to an even lower 14.0v absorption so that it shuts off early. The batteries can easily take 6 minutes at 14.0. My Victron Multi which has a minimum absorption time of one hour is set to the same 14.0.v. Kilovault techs approved this.

.

again semi wrong ,AL case LIFEPO4 4/8/16 S usually go in disbalance because thiny 5-8mm bolt use for connecting cell low torque. (bad connection,heating bolt and tinny connection spot. and their start disbalance. sometime 5A active balancer can do job. winston cell use m10-12 bolt high torque.But also and winston cell bolt must be checked by time.
kilvault is topband battery china.
https://www.topbandbattery.com/Products/3592.html

https://www.youtube.com/watch?v=T19hu6gRF5U

[maine-cruiser]

Originally Posted by rgleason

Bill can you describe your system more completely, or do you have diagram? I am interested.

My friend Goboatingnow posted a diagram that I worked on in this thread
https://www.cruisersforum.com/forums...ml#post3682941
The goal was to have an easily established procedure for emergency operation when the LFP or BMS failed and to be ABYC compliant.
This thread generated a lot of discussion and thought. This diagram was based upon great input from Goboatingnow, Hjohnson and Wholybee. It is somewhat similar and derived from the system that Hjohnson has on his boat. After costing it out I found that it would be more $ than I could afford for the purpose.

Later s/v Jedi Nick who is very active and knowledgable in this forum posted another good diagram which makes the Alternator the primary charge source https://www.cruisersforum.com/forums...ml#post3681055

Since doing the diagram and thought process that Goboatingnow posted, I have some other ideas for a system, which I may more completely develop, but right now I find this drop-in approach very interesting.

We need to develop a really simple system that complies with all aspects of ABYC, and I can't understand why Dropin manufacturers refuse to add canbus communications with a remote alternator regulator (Balmar or Wakespeed or Nordkyn, or ??) which will alert and send a simple signal (NO/NC contact) to the regulator to shutoff the alternator field.

This simple improvement would make a huge difference in safety and operation of LFP. How many years will we have to wait?

The other essential improvement would be to beef up the BMS FETS and wiring so that Alternator charging at good C rates is reasonably achievable with some factor of safety.

My problem is also finding the space below for the batteries and BMS.

I will attempt to attach the schematic that I used. I derived this from a Victron schematic. It could be simplified. For instance the Cyrix relay is probably redundant since all the charge sources are properly programmed for LFP. In the four seasons I've used this system I don't think the BMS has ever issued a charge disable signal. The programmed charge sources reach the absorption voltage and go to float.

Bill

[phantomracer]

Originally Posted by TxCoastSailor

Sounds to me like you need a different alternator regulator. Try the Wakespeed 500.

The point he was making, and what I am worried about, which may be an irrational fear... is that once the battery gets 'full', not over charged, just 'full', there is the possibility the BMS will disconnect. Thus losing my navigation/AP/everything. As it is now my AGM(Firefly) have no issue getting 'full' pretty quickly '100%' on the Smartgauge.


Again, might be an irrational fear. This is new to me,



Apparently this is why others have suggested a buffer battery, in parallel, through an argofet, or with a DC/DC charger


In any of the cases, from what I understand, I can't start from the LFP bank, so i have no backup to the starting battery, which means I might need a second starting FLA/AGM battery as a backup (or jump pack or something)



All this is making me consider throwing in 2 6v GC-2 wet cells in might be a better choice when my batteries give up the ghost!



I do want to get on the LFP bandwagon, but there doesn't seem to be much consensus, or is too complicated, to use drop-in LFPs to make it a near failsafe system

[The Yacht Rigger]

Originally Posted by phantomracer

The point he was making, and what I am worried about, which may be an irrational fear... is that once the battery gets 'full', not over charged, just 'full', there is the possibility the BMS will disconnect. Thus losing my navigation/AP/everything. As it is now my AGM(Firefly) have no issue getting 'full' pretty quickly '100%' on the Smartgauge.


Again, might be an irrational fear. This is new to me,



Apparently this is why others have suggested a buffer battery, in parallel, through an argofet, or with a DC/DC charger


In any of the cases, from what I understand, I can't start from the LFP bank, so i have no backup to the starting battery, which means I might need a second starting FLA/AGM battery as a backup (or jump pack or something)



All this is making me consider throwing in 2 6v GC-2 wet cells in might be a better choice when my batteries give up the ghost!



I do want to get on the LFP bandwagon, but there doesn't seem to be much consensus, or is too complicated, to use drop-in LFPs to make it a near failsafe system

We do a lot of lithium system installations, most of which end up being 24v or 48v main banks, with a smaller "buffer bank" - often utilizing the original AGM batteries with DC-DC chargers to charge from the lithium bank. Then we convert as much as possible in terms of high draw appliances and systems to the higher voltage for direct draw on the lithium bank. The lithium bank is charged by solar, shore power, and high output externally regulated alternators.

We're using Arco Zeus regulators now, they will protect the alt in case of a shut down, as well as offer really good power curve charging profiles to keep the engine load ideal - and of course monitor battery voltage and temp settings.

Also the Zeus does generator mode, a completely unique setting for an external regulator - allowing you to charge incredibly fast with the engine in neutral while on anchor. https://theyachtrigger.com/arco-zeus...tor-regulator/

[sailingharry]

Originally Posted by The Yacht Rigger

Also the Zeus does generator mode, a completely unique setting for an external regulator - allowing you to charge incredibly fast with the engine in neutral while on anchor. https://theyachtrigger.com/arco-zeus...tor-regulator/

We keep hearing that. My ancient Balmar regulator will provide as much field as necessary to attain the desired voltage. Once at full field, I can't do anymore.
This generator mode completely baffles me. Do you simply provide full field without regard to voltage? Do you set a temporary "super bulk" target voltage?
Where and when and how would you ever use this generator mode and what specifically happens that is different than a conventional regulator?

[The Yacht Rigger]

Originally Posted by sailingharry

We keep hearing that. My ancient Balmar regulator will provide as much field as necessary to attain the desired voltage. Once at full field, I can't do anymore.
This generator mode completely baffles me. Do you simply provide full field without regard to voltage? Do you set a temporary "super bulk" target voltage?
Where and when and how would you ever use this generator mode and what specifically happens that is different than a conventional regulator?

Apologies, I thought this had been explained in another thread.

If you run a high output alternator at full capacity (full field) at low RPM's while in gear, you are going to bog down the engine since it is operating at the low range of it's power curve. This is why other regulators have been developed in the past to create an output power curve that raises the field current as the RPM's increase, to a point, so that the alternator is only at full field when the engine is at the peak of it's power curve - your normal cruising RPM's hopefully. It then backs off again as you rev higher, so that in a situation when you need maximum engine power, you aren't robbing the engine of power with an alternator that is creating a bunch of load at full field.
Same goes for the lower RPM situations, entering marinas, navigating tricky waters, etc. You don't want full field in those lower zones of the engine power curve.

The same rules don't apply when running the engine in neutral, but increasing RPM's, because you are not sharing the load with a spinning propeller. So for instance, when on anchor, you have run your batteries down overnight, and you want to quickly charge them up before you let solar take over. You fire up the engines, but do you really want to run them at 2500rpms (or whatever the power curve dictates on your specific engine)? No, ideally you want to run the engines as low as possible but still produce maximum field. Less noise, less fuel burn - but still 100% field - so you can charge really fast.

This is what generator mode is. It engages full field at lower RPM's than the programmed power curve you have setup for normal motoring in gear, but of course the engine needs to be in neutral. If the Zeus senses a change of rpm's of more than 200, for instance if you forget you are in generator mode and slide the gearshift back to idle, it will disengage generator mode and return to the progreammed settings, probably around 40-50% of the alternators capacity (at idle).

And yes, of course the regulator is still monitoring battery voltage, temp, etc so that if you engage generator mode at nearly a full state of charge it will derate itself accordingly as the full state of charge is met.

[rgleason]

Thank you.

Generator mode: Engages full field at lower RPM's than the programmed power curve for normal motoring in gear. Engine needs to be in neutral, if a change of rpm's is sensed > 200, the regulator will return to the programmed settings, around 40-50% of the alternators capacity at idle.

This sounds like the reverse of putting an Engine low mode switch on the temp sensor of the Balmar 618 for long motoring trips, to prevent overcharging the batteries which drops the field down about 50%.


Maybe just run a direct line around the regulator with a rheostat and back off when you smell plastic. (Ha Ha.)

[rgleason]

Is there any easy way to do this?

[sailingharry]

Thank you. My old Balmar regulator does not have the dial back for low engine rpms. The alternators kind of take care of that themselves, as at lower RPM they only put out about 20% of rated power. I was unaware of any regulator that reduced alternator output as a function of RPM (although the Balmar has an easy switch that can be added to run it 50% load or turned off). So I guess I always have the "generator mode" engaged! I only have 3 kW of alternators on my engine, so I haven't seen the need to dial back -- but I can see that there are situations where that might be useful.

But thank you. I now understand what that mode is even if I don't appreciate its value.