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

[css145hs]

Thanks for clarifying about the MC-614. I'll go with 14.0/13.8/13.2, a tad bit safer.

[Joe Parklane]

Thanks to all for the responses.
My installer/designer was out of town but has returned and responded to my e-mail which has put me a ease with my current set-up. I have been using an inaccurate term when stating my bank is a 100% SOC. The reality is that he set the BMV based on 90% of the bank capacity so when it reads a 100% it is well below the high shoulder. Float voltage setting is low enough 13.34 volts that no current is going into the bank verified by fluke. I always worry over these but in this case must rely on someone who knows and installed the system and is an engineer who has designed/installed several systems and researched these types(for novices e.g. me) of applications.


Again, Merry Christmas and Happy Holidays to all and may the smoke stay in the wires and electron work when called.

Joe

[diugo]

Originally Posted by transmitterdan

Because for boats plugged in or using solar (and unattended) it's not easy to find a charger/power supply that will do that [turn off] without external help. This extra connect/disconnect circuitry complicates the system, reduces reliability and increases the cost of an already costly technology. There is no shame in looking for an easy/cheap solution. It's what is needed for Li technology to gain wider acceptance.

From a design standpoint it's really no harder for a charger to go into "off" mode than into "float" mode. Especially since most better chargers these days are microcontroller controlled---so it could be just a matter of uploading LFP-specific firmware.

I suspect some boaters underwent similar personal turmoil when upgrading to incandescent lighting from whale oil. "All them wires and switches and fuses and batteries do nothing but complicate the system, reduce reliability and increase cost," they whined.

In a nutshell, the reason float charging any lithium ion cell is bad is this: the float charger is an essentially endless source of available electrons. Floating provides a catalyst for loosely intercalated lithium ions to be "picked off" by opportunistic electrons---converting vulnerable ions on the surface of the anode back into metal atoms. In other words, lithium plating.

[transmitterdan]

Originally Posted by diugo

From a design standpoint it's really no harder for a charger to go into "off" mode than into "float" mode. Especially since most better chargers these days are microcontroller controlled---so it could be just a matter of uploading LFP-specific firmware.

Yes, I agree but what charger/inverter can I buy that does this? And to further complicate things it also needs to supply house power while simultaneously not draining or charging the batteries (i.e. it must isolate the Li pack). This is not just a firmware update. The charging circuit has to divert current away from the battery whilst maintaining house voltage thus leaving the batteries at a different voltage than the house bus. Adding multiple and possibly simultaneous charge sources such as solar/alternator/wind makes it even more interesting. Add to that the requirement for individual cell monitoring to detect battery failure and the hardware changes get more profound.

Is there an off the shelf charger for typical cruisers that can handle LI packs now? I am not aware of any.

Originally Posted by diugo

I suspect some boaters underwent similar personal turmoil when upgrading to incandescent lighting from whale oil. "All them wires and switches and fuses and batteries do nothing but complicate the system, reduce reliability and increase cost," they whined.

Funny. A sure way to get people to not adopt a new technology is through ridicule. For the record I am not against Li. I just hope it can be made easier than LA in addition to Li's other redeeming qualities.

Originally Posted by diugo

In a nutshell, the reason float charging any lithium ion cell is bad is this: the float charger is an essentially endless source of available electrons. Floating provides a catalyst for loosely intercalated lithium ions to be "picked off" by opportunistic electrons---converting vulnerable ions on the surface of the anode back into metal atoms. In other words, lithium plating.

No one disputes why it is a requirement. What we lack is a unified solution that mere mortals can install and forget about. Li batteries don't need human intervention like FLA so the reality is that for mass acceptance the technology has to be "install and forget" until notified that batteries must be replaced. My laptop has this technology so it is possible.

[senormechanico]

After 3394 posts, I'm not sure if this link has been shown or not, but I figured it couldn't hurt.
It is addressing the long term damage of over charge as anything above 4 volts (Winston) and somewhat lower voltages for other brands.

http://www.auto88.cz/_info/Doc/GWL-P...OverCharge.pdf

It seems to assume the BMS is holding the cell voltage at 4 volts. The Clean Power Auto BMS (which I have) activates HVC if any one of the cells reaches 3.75 V. So far, in both of my installations (house and boat), HVC has never occurred, although a couple of the boat's cells experience shunting when the engine is running.

[downunder]

Originally Posted by senormechanico

After 3394 posts, I'm not sure if this link has been shown or not, but I figured it couldn't hurt.
It is addressing the long term damage of over charge as anything above 4 volts (Winston) and somewhat lower voltages for other brands.

http://www.auto88.cz/_info/Doc/GWL-P...OverCharge.pdf

Thanks Explains overcharging well.

[goboatingnow]

Originally Posted by transmitterdan

Yes, I agree but what charger/inverter can I buy that does this? And to further complicate things it also needs to supply house power while simultaneously not draining or charging the batteries (i.e. it must isolate the Li pack). This is not just a firmware update. The charging circuit has to divert current away from the battery whilst maintaining house voltage thus leaving the batteries at a different voltage than the house bus. Adding multiple and possibly simultaneous charge sources such as solar/alternator/wind makes it even more interesting. Add to that the requirement for individual cell monitoring to detect battery failure and the hardware changes get more profound.

Is there an off the shelf charger for typical cruisers that can handle LI packs now? I am not aware of any.

Funny. A sure way to get people to not adopt a new technology is through ridicule. For the record I am not against Li. I just hope it can be made easier than LA in addition to Li's other redeeming qualities.

No one disputes why it is a requirement. What we lack is a unified solution that mere mortals can install and forget about. Li batteries don't need human intervention like FLA so the reality is that for mass acceptance the technology has to be "install and forget" until notified that batteries must be replaced. My laptop has this technology so it is possible.

Unfortunately right now , the plug and forget setup is not available off the shelf using conventional existing marine equipment.

Your laptop has a custom dedicated charger specifically designed to nabobs that battery. Boats have a hodge podge of gear sourced fr different companies , hence the difficulty.

Dave

[Maine Sail]

Originally Posted by senormechanico

It seems to assume the BMS is holding the cell voltage at 4 volts. The Clean Power Auto BMS (which I have) activates HVC if any one of the cells reaches 3.75 V. So far, in both of my installations (house and boat), HVC has never occurred, although a couple of the boat's cells experience shunting when the engine is running.

The CP BMS breaks the entire bank away at 15V / 3.75VPC. It activates High Voltage Cut at 14.2V / 3.55VPC.

If yours is not breaking an HVC relay until 15V it is simply not wired correctly. If using the HVC feature with a CP BMS you should not be able to charge at all above 14.2V or 3.55VPC... Once you hit 14.2V with the CP BMS it drops out the charging sources. I have talked with Dimitri and he admits that he needs some hysteresis in the HVC cut/make but other than that it works as advertised and breaks solar, alt, wind or a shore charger at 14.2V .....

The 3.75VPC is your last ditch safety contactor, not your HVC relay. You should not be able to charge your bank beyond 14.2V or 3.55VPC with a CP BMS if it is properly wired/configured.

[dlentz]

Originally Posted by Maine Sail

The CP BMS breaks the entire bank away at 15V / 3.75VPC. It activates High Voltage Cut at 14.2V / 3.55VPC.

If yours is not breaking an HVC relay until 15V it is simply not wired correctly. If using the HVC feature with a CP BMS you should not be able to charge at all above 14.2V or 3.55VPC... Once you hit 14.2V with the CP BMS it drops out the charging sources. I have talked with Dimitri and he admits that he needs some hysteresis in the HVC cut/make but other than that it works as advertised and breaks solar, alt, wind or a shore charger at 14.2V .....

The 3.75VPC is your last ditch safety contactor, not your HVC relay. You should not be able to charge your bank beyond 14.2V or 3.55VPC with a CP BMS if it is properly wired/configured.

Just FYI; CP sells two cell boards, one @ 3.6v/cell and one @ 3.8v/cell
Interesting, he now has a note/caution to order the 3.6v boards with the "HousePower board" I don't believe that was always the case.

Dwain

[Maine Sail]

Originally Posted by dlentz

Just FYI; CP sells two cell boards, one @ 3.6v/cell and one @ 3.8v/cell
Interesting, he now has a note/caution to order the 3.6v boards with the "HousePower board" I don't believe that was always the case.

Dwain

I have the 3.6V boards and Dimitri told me to order those at least a year ago...

Still the HP BMS does the charge HVC at 3.55VPC / 14.2V regardless of whether you have the 3.8V or 3.6V boards...

[senormechanico]

Oh Great !
I have the earlier version 3.8 v. boards on the boat (HiPower cells) and the current version 3.8 boards on my home's bank. I ordered the home's boards a couple of months ago, and even put in a question on the order if these were indeed the correct ones for Winstons. No response to the question in the order, and the 3.8's were sent.

BTW, my boat's setup has a solid state relay connected to the HVC output for the shore charger I never even use, and the alternator field disconnect is 99% wired. Alt output is exactly 14.2 volts when cells are full. I want to finish that wiring, but life keeps getting in the way. All I still need to do is buy, mount and connect a relay !

The earlier version boards on the boat have a green and red led. Green is "everything ok", red and green together is "ok but shunting" and red is "HVC shutdown".
I've seen green, red and green, but never red only.
When shunting, if I remember correctly, the boat's cells read 3.70 with my Fluke 77.

The home's system will alarm at 28 .4v if I push it from the Midnite Solar MPPT, but I've never seen any shunting.
The newer boards have a single red blinky led. Different patterns indicate LVC, ok, shunting, HVC etc.

[Maine Sail]

Originally Posted by senormechanico

Oh Great !
I have the earlier version 3.8 v. boards on the boat (HiPower cells) and the current version 3.8 boards on my home's bank. I ordered the home's boards a couple of months ago, and even put in a question on the order if these were indeed the correct ones for Winstons. No response to the question in the order, and the 3.8's were sent.

BTW, my boat's setup has a solid state relay connected to the HVC output for the shore charger I never even use, and the alternator field disconnect is 99% wired. Alt output is exactly 14.2 volts when cells are full. I want to finish that wiring, but life keeps getting in the way. All I still need to do is buy, mount and connect a relay !

The earlier version boards on the boat have a green and red led. Green is "everything ok", red and green together is "ok but shunting" and red is "HVC shutdown".
I've seen green, red and green, but never red only.
When shunting, if I remember correctly, the boat's cells read 3.70 with my Fluke 77.

The home's system will alarm at 28 .4v if I push it from the Midnite Solar MPPT, but I've never seen any shunting.
The newer boards have a single red blinky led. Different patterns indicate LVC, ok, shunting, HVC etc.

I think you are going to find that you are tripping HVC as you come up to voltage. Depending upon the regulator this may not be the best thing for it as there is no hysteresis and it will shut on and off as fast as the voltage drops away from 14.2V... I found that even regulating to 14.1V it would occasionally bump 14.2V, as loads came on / off etc., and trip HVC. With the Balmar MC-614 14.0V is about the max you'd want with the House Power BMS. Unfortunately I don't know of any alt regs that can be adjusted in .5V increments.

Be sure you are cutting the regulator according to how the manufacturer wants you to do so. Balmar wants the regulator B+ cut not the field or ignition wire. Never cut the alternator output wire / alt B+ or...... POOF....!

[senormechanico]

I have the Leese Neville Series with the adjustable single stage alternator described in your excellent "How To" series. The voltage adjustment is all the way down.
I'm perfectly happy with it otherwise, but it would be great if I could add a diode somewhere to change the sense setting to 13.8 volts.


Thanks for all your
excellent posts!

[Jd1]

Originally Posted by Maine Sail

Be sure you are cutting the regulator according to how the manufacturer wants you to do so. Balmar wants the regulator B+ cut not the field or ignition wire. Never cut the alternator output wire / alt B+ or...... POOF....!

Could you please clarify this statement for me? It seems that you are saying that Balmar wants you to cut B+ but cutting B+ will vaporize the diodes.
?????????????????

Edit: Never mind, just figured it out .... cut the B+ to the regulator but NOT the B+ from the alternator

[Maine Sail]

Originally Posted by senormechanico

I have the Leese Neville Series with the adjustable single stage alternator described in your excellent "How To" series. The voltage adjustment is all the way down.
I'm perfectly happy with it otherwise, but it would be great if I could add a diode somewhere to change the sense setting to 13.8 volts.


Thanks for all your
excellent posts!

I would suggest converting it to external if feeding Li and then gain alt temp sensing (NEEDED) & Belt Manager / current limiting (NEEDED) etc..... That is a nice little alt but it will get BEAT UP badly like Mike Tyson on Urkel....