LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

[goboatingnow]

Originally Posted by Maine Sail

Dave,

I have a few items:

*HTC - High Temperature Cut Individual cell temp monitors for each cell.

*LTCC - Low temp CHARGING cut. Loads still allowed but no charging. Same monitors but no charging allowed below 0C/32F..

*I would also prefer a device that can drive latching relays such as the Blue Sea 7712 etc..

*Can incorporate charge HVC / Load LVC cuts at a warning level and emergency level.

*Can have LVC and HVC levels adjustable as well as hysteresis on warning level

*user configurable warning and emergency level outputs selectable normally closed or normally open (gives more options when choosing relays & contactors)

*Any balancing must be done manually and preferably "attended" just like equalization charging. A manual override of warning level HVC would be required to drive the bank to shunting levels.

I know I have more and will think of them the minute I am away from the computer.....

Sorry , I didn't specifically reply to this post

HTC/Cell tem monitoring , good idea more complexity, not sure how it would be possible to seriously temperature insulate each monitor by cell.

LTCC, zeros degree lockout , good idea , easily added. ( do we need another LED!)


Bistable relays: this usually requires a on pulse and a separate OFF pulse ( mind you some are toggle relays) . Again this doubles the number of relays on the BMS board, ( some of these relays need to handle ~10A as the main contactor/bistable relay switches.

The thing I don't like about bistables, is you have to handle failed to respond situations

as to adjustable levels, all this stuff is really User Interface, SO thats why I propose to open source the hardware and software, Other scan add those features, personally , Ill just blow a board with the code preconfigured for my cells. !

HVC override for balancing, this can be achieved by silencing the alarm. HVC events would still occur and open the HVC contractor, so what, balancing will be done on the "cell/battery" side of the contractor anyway

Again as to limits , I propose HVC( Charge contractor activated ) , Upper user charge level reached, lower user discharge reached , LVC ( load contactor activated), and cell out of balance alarm ( no contractors activated , if HVC <cell > LVC )

I dont intend to commercialise thus othe then getting enough interest on Indigogo to produce some boards ( 20-50) and optional front panels.

dave

[msmith132]

Rolf and others,

Thanks for the responses. Everything is ordered, and now the waiting game begins. I'm really looking forward to this installation, lead acid has always been such a pita in terms of long term dependable performance and charge acceptance rate limitations.

Michael

[mcarling]

Originally Posted by msmith132

lead acid has always been such a pita in terms of long term dependable performance and charge acceptance rate limitations.

In my opinion, lead-acid is a dreadful choice for boats compared to LiFePO4 on the basis of reliability, safety, performance, weight, life-cycle cost, charge rate complexity, and lead-acid's greater need for cell-level voltage monitoring compared to LiFePO4.

[FlyingCloud1937]

wow, you must be in WA. State, where recreational maryjane is legal?

Originally Posted by mcarling

In my opinion, lead-acid is a dreadful choice for boats compared to LiFePO4 on the basis of reliability, safety, performance, weight, life-cycle cost, charge rate complexity, and lead-acid's greater need for cell-level voltage monitoring compared to LiFePO4.

[FlyingCloud1937]

What no HVC, dump-load before alarm?, then cut to alarm, Then cut to DC?

lloyd

Originally Posted by goboatingnow

Sorry , I didn't specifically reply to this post

HTC/Cell tem monitoring , good idea more complexity, not sure how it would be possible to seriously temperature insulate each monitor by cell.

LTCC, zeros degree lockout , good idea , easily added. ( do we need another LED!)


Bistable relays: this usually requires a on pulse and a separate OFF pulse ( mind you some are toggle relays) . Again this doubles the number of relays on the BMS board, ( some of these relays need to handle ~10A as the main contactor/bistable relay switches.

The thing I don't like about bistables, is you have to handle failed to respond situations

as to adjustable levels, all this stuff is really User Interface, SO thats why I propose to open source the hardware and software, Other scan add those features, personally , Ill just blow a board with the code preconfigured for my cells. !

HVC override for balancing, this can be achieved by silencing the alarm. HVC events would still occur and open the HVC contractor, so what, balancing will be done on the "cell/battery" side of the contractor anyway

Again as to limits , I propose HVC( Charge contractor activated ) , Upper user charge level reached, lower user discharge reached , LVC ( load contactor activated), and cell out of balance alarm ( no contractors activated , if HVC <cell > LVC )

I dont intend to commercialise thus othe then getting enough interest on Indigogo to produce some boards ( 20-50) and optional front panels.

dave

[goboatingnow]

Originally Posted by FlyingCloud1937

What no HVC, dump-load before alarm?, then cut to alarm, Then cut to DC?

lloyd

explain?

the proposed alarms and event are ( reading from the bottom)

HVC - alarm , charge control relays activated
Upper user level - Alarm, indicators etc
Lower user level - Alarm ( persistent) , indicators
LVC - alarm, Load control relays activated
VLVC - all relays activated ( very low voltage ) **

** not sure of this

dave

[FlyingCloud1937]

Originally Posted by goboatingnow

explain?

the proposed alarms and event are ( reading from the bottom)

HVC - alarm , charge control relays activated
Upper user level - Alarm, indicators etc
Lower user level - Alarm ( persistent) , indicators
LVC - alarm, Load control relays activated
VLVC - all relays activated ( very low voltage ) **

** not sure of this

dave

By adding an additional relay that activates prior to the now 1st event Alarm Mode. The new relay would now be the first event, which closes a relay into a dump-load into an immersion heater in the domestic HW supply 12/24/48 what ever the nominal bat voltage is.

This would do useful work, and probably stop the now 2nd event Alarm Mode, as well as the need to a full blown HVC evvent.

Lloyd

[goboatingnow]

Originally Posted by FlyingCloud1937

By adding an additional relay that activates prior to the now 1st event Alarm Mode. The new relay would now be the first event, which closes a relay into a dump-load into an immersion heater in the domestic HW supply 12/24/48 what ever the nominal bat voltage is.

This would do useful work, and probably stop the now 2nd event Alarm Mode, as well as the need to a full blown HVC evvent.

Lloyd

Good idea. Number of relays has now grown even more. ! Don't see the need for another trip point though. The load dumping relay could just be activated on the user selectable high voltage point , ie the end of charge point

Dave


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[markv]

Just got 16 x 400Ah CALB batteries delivered to my new Lagoon 450 in Les Sables-D'Olonne, along with a Ligoo BMS...

We are not electricians, so we hope to get someone from Robin Marine on MOnday (it's Sat/Sun here now) to help us install the system. If we can't find someone, then we may have to do it ourselves with the help of Peter at Calb who is great at support... We've assembled it on the table at the moment, trying to get our head around the Ligoo BMS..

Robin Marine have already installed the Victron inverter/charger, except for the VE unit which has not arrived yet...We have to connect part of the Ligoo BMS to the Victron...

Anyway, here's a diagram supplied by Peter at Calb, ... any comments most welcome - we also have to install the 6 solar panels with 2 Flex Max 80's. No large generator, just an emergency 2kw Yamaha portable one.

Just as an aside, the make of the alternators is Valeo, 125Amps - anyone have experience of these?...Do I need to get a voltage regulator or are they OK to charge the batteries directly?

[sparrowhawk1]

Not sure I should even comment because the knowledge I'm repeating is what I read mostly on this site. It's my understanding that you want to hook all your batteries up parallel and let them sit for a few days. that will help get them all to exactly the same voltage

[markv]

The've been pre balanced by CALB, using that method. We have the connector bars all set up so it is 4P4S configuration, with an active balancer connected to each bank of 4..

Just reading through past threads as to connection of solar panels. Either directly to the bank or to the bus bar before the cutoff relay from the BMS so the BMS controls the relay and will cut the connection if the solar regulators fail in any way. I am using Flexmax 80 MMPTs and will set max charge at 13.8.

Talking of contactors, I have 2 supplied with the BMS..one larger than the other. One has ZJW600A/12v marked on it and is the bigger one, the smaller one has no markings on it. Just curious how they are actually connected in practice. The electrician should know, I am just learning at the moment.

Here's a picture of what we have so far...

[roetter]

The paralleling for balancing only makes sense during a charge (top balance). The "un-balance" only shows up at higher voltages. Just connecting them to parallel while not being charged does next to nothing.

To balance:
a - you charge the cells in parallel slowly to about 3.6V. This is my personal max. I only charge to 3.45/cell (13.8V) normally.
or
b - hook them up in series (as in your schematics) and keep measuring each cell - or cell set - as you charge to 14.4V (3.6V/cell) and short the high cells with a good length (10+m) of standard house wiring cable. These cables get hot, so you may not be able to do more than a few seconds at a time. Keep doing this until you get the cells within 30mV or so at 3.6V.

I use a "calibrated" Junsi to do measure the cell voltages. By calibrated I mean that the Junsi reads for every cell, or cell-set, the same as my multi meter reads. That way I can see each cell voltage immediately as I am placing the cable on to do the short. It takes about 30 minutes to do the balancing from the time the cells start going up in voltage - i.e. 3.45 and higher. If I can not keep up with "pulling" the high cells down with the short, i will stop the charging and drain the high cells, then start charging again.

The second options lets you do the balancing at any time, even if you have to rebalance after a few years.

I added an updated schematics for the cell connections.
Attachment 85639

Good luck with everything.

[roetter]

Originally Posted by markv

Just reading through past threads as to connection of solar panels. Either directly to the bank or to the bus bar before the cutoff relay from the BMS so the BMS controls the relay and will cut the connection if the solar regulators fail in any way. I am using Flexmax 80 MMPTs and will set max charge at 13.8.

Talking of contactors, I have 2 supplied with the BMS..one larger than the other. One has ZJW600A/12v marked on it and is the bigger one, the smaller one has no markings on it. Just curious how they are actually connected in practice. The electrician should know, I am just learning at the moment.

Two bus bars (charge and load) make sense, as otherwise it gets messy very quickly. There are several connections that need to be removed from the house battery main switch and placed on the "safe sides" of the solenoids.

You need to move the "double" alternator charge cables (one from port and starboard alternator each on one lug) from the battery-side of the master switch to the charge bus bar, otherwise the alternator will overcharge your house bank during long motoring, especially when it is sunny and solar does a lot of the work already. From the charge bus bar you go through the smaller solenoid to the house battery positive.

The larger solenoid is for the load bus bar. I hope it can handle 300A continous and at least 500 peak. I assume you have electric winches.

The winch cables, and the cable to the 12V main panel need to be removed from the main bank switch and move to the load bus bar.

I have my Victron on the load bus bar (your schematics shows it not going through it), so that it will not deplete my house bank. I totaly rely on the Victron to not fail on the charge side. However, I am almost never in a marina, and if I am, I unplug after being charge and plug in again after a day or two.

I hope you have the Victron USB programming interface box to set the charger up properly for LiFePo. Do not use their standard voltage settings though. The voltages are too high. But you already plan on 13.8V which is good.

Let me know if you need more detailed information.

[markv]

Rolf

thanks for the info...starting to make a bit more sense now. Took some pictures, you will probably remember this as the setup that comes from Lagoon. I think we will have to put the bus bars on the opposite side of the switches, and the Flexmax MMPTs and BMS modules on in the space where the Victron is currently.

The Victron is connected to the Load as far as I can see.

[Moonos]

Originally Posted by markv

Just got 16 x 400Ah CALB batteries delivered to my new Lagoon 450 in Les Sables-D'Olonne, along with a Ligoo BMS...

Sounds like a great setup, I will be watching with interest as that is similar to what I would like to setup when I get my boat.