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

[Jd1]

Please forgive the stupid question but what happened to Housepower ? I have their BMS and so far it's been doing a fine job. It's a bit unnerving though if they are no longer around.

[alctel]

Originally Posted by Jd1

Please forgive the stupid question but what happened to Housepower ? I have their BMS and so far it's been doing a fine job. It's a bit unnerving though if they are no longer around.

As far as I can tell, they got bought out by a bigger manufacturer and the product was shelved.

[Jd1]

Originally Posted by alctel

As far as I can tell, they got bought out by a bigger manufacturer and the product was shelved.

Bummer

[john61ct]

Any 'youse got comments on these?

http://www.ebay.com/itm/192202522951

http://www.ebay.com/itm/192197820753

http://www.ebay.com/itm/192184401903

I particularly like the built-in overcurrent protection some of these offer.

Other suggestions for better setpoint-adjustable LVDs, or VSR/ACRs that can also work as load LVDs would be most welcome.

Especially handling higher current loads with the overcurrent shutdown.

[alctel]

Ok, after trolling through the internet, I found the following BMS options - does anyone have opinions?

MK3x4SMT Digital Lithium Regulator
Manzanita Micro

Orion BMS JR
https://www.orionbms.com/products/orion-bms-jr/

REC ACTIVE BMS
REC d.o.o.

[downunder]

Originally Posted by alctel

Ok, after trolling through the internet, I found the following BMS options - does anyone have opinions?

MK3x4SMT Digital Lithium Regulator
Manzanita Micro

Orion BMS JR
https://www.orionbms.com/products/orion-bms-jr/

REC ACTIVE BMS
REC d.o.o.

Try EV power BMS They have been at it for a fair while and seems relatively fair cost wise.
EV Power - Australian Electric Vehicle Specialists — EV Power - Australian Electric Vehicles sells Electric Bikes and car conversions, Electric Bicycles, Electric Vehicles, Conversion Kits.

[downunder]

There are at least 4 australian providers of engineered Lithium systems for boat applications.

I would be interested in any feedback by and of the experts here on CF on the relative merits of these systems.

Lightwave have now 5 such installs using the Outback Marine system. According to the independent electrician who does the install for Lightwave there have been no issues whatsoever.

1. Outback Marine Energy Storage Lithium Battery Systems

2. Enerdrive The Lithium Battery - The Ultimate Energy Storage System

3. EV power EV Power - Australian Electric Vehicle Specialists — EV Power - Australian Electric Vehicles sells Electric Bikes and car conversions, Electric Bicycles, Electric Vehicles, Conversion Kits. Sail/surf/roam has one of these systems and also IMPI has just installed an 800AH system

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

4. EVO Lithium https://www.evolithium.com.au/

Cheers

[alctel]

Originally Posted by downunder

Try EV power BMS They have been at it for a fair while and seems relatively fair cost wise.
EV Power - Australian Electric Vehicle Specialists — EV Power - Australian Electric Vehicles sells Electric Bikes and car conversions, Electric Bicycles, Electric Vehicles, Conversion Kits.

Ah man, this looks great.

I just put down the money this morning for the Orion JR, at almost twice the price

[OceanPlanet]

A couple years back we built a small portable 48v battery in a Pelican case, using the Orion Jr. BMS and Enerdel cells. I was impressed with the Orion functions however it still couldn't do everything we wanted. A main take-away from the whole thing was that 48v it's a lot trickier to do right than 12v & 24v (precharge resistors, delay timers for relays, etc.). However we learned a lot.

That experience along with hundreds of 12v & 24v marine lithium applications eventually led to us collaborating with Lithionics to create the modular BMS we do now.

Attached is an overview and flow chart of the functionality.

[Maine Sail]

So here I sit on board the boat, on the mooring, with the Honda generator chugging away in my work skiff, which is tied behind the boat. No matter where I placed the Honda generator on the boat, both of my CO alarms go off. IMHO things are a Darwin Award creator for sure..P

So why am I running a portable generator? Why, because one of the BMS cell boards decided, all on its own, that it need to shunt energy from cell#2 100% of the time.

By the time I noticed it, had not been on-board in a few days, cell #2 had become way out of balance with the others. The cell board failure happened when we were not on-board and with the bank sitting at approx 62% SOC...

Here we have a case where a BMS failure actually caused cells to go out of balance, not to stay in balance. Lucky for me I had a spare cell board and I am now sitting here rebalancing a pack that has not needed any balancing in 862 cycles...

So much for trying to get to 1000 cycles without any balancing. The old cell board is being sent out for repair and hopefully I can get an answer as to why it went tits up on me?

On the good side the BMS saved the BMS from itself and also saved my cell.. If I had not yet fully convinced myself that balancing is unnecessary, at the charge voltages I use, I am now... I plan to talk to the designer and see if the BMS's other parameters will be impacted if the resistors are physically removed from the cell boards. I personally have zero need for automated balancing as evidenced by the previous 861 cycles.

To test some theories, I discovered this last Thursday before we were leaving on a four day weekend sail, I decided to simply lower peak charge voltage to 13.7V and set an alarm for the low cell. It worked like a charm, though with less capacity, and we continued to use the out of balance bank without the high cells pushing over 3.55V and triggering HVC due to the imbalance.

If I had to take the LFP off-line the Firefly AGM was sitting on the bench waiting for the coach to play him. Despite the injury, the star player pulled through.

All in all the cell board replacement, and quick regulator re-program of the alt reg, took about 25 minutes. The hard part is now to re-balance the pack on the boat on a mooring. More just tedious than difficult though...

My B&K 60A bench top power supply has been running flat out for 2:10 and the low cell is still only at 3.41V once it gets to 3.55V and 10A the pack will be wired in parallel and charged to 3.6V and 0.0A to 0.1A. Before I leave tonight I will parallel wire it and tomorrow will push it to 3.6V..

I suppose it never hurts to do a manual rebalance it just kills me that it was caused by the very thing we install to try and protect our banks... I am not really surprised by this and accept that it is just one of the prices you pay to be on the bleeding edge...

A new feature on my dream BMS is a manual lock-out for cell balancing so this type of failure mode can't occur..

[OceanSeaSpray]

Boats should use centralised BMS units. With the high charging currents we get, the cell voltages get jacked up early, before the cells are near full, and cell boards can then start shunting and throw the whole pack out of balance. The concept itself is wrong for the application.
If you keep charging until full (when the current has tapered down), then shunt balancers get a chance to correct early errors. This works when you charge an EV overnight with a perfect CC/CV/Terminate regime and a modest current, but not on boats where we often don't get to the end of the cycle.
The fundamental problem is that the cell boards have no idea of the battery current and cell internal resistance. They should only shunt when the current is low and the voltage high, but in reality they will shunt at any current. It is such a problem that the shunting voltages are almost invariably set very high, which defeats the purpose.

The #1 driver behind cell-board schemes is commercial: you can offer it to everybody regardless of the number of cells. Having intelligent cell boards would require a lot of more than a 1-wire current loop to get a system operating correctly and then the economics are not looking so attractive.
The control unit in a cell board scheme basically has next to nothing in it: it monitors the loop and takes action on 2 or 3 voltage conditions without even knowing where they originated. The HV thresholds are frequently very high so the system stays put when you drop it into an installation that had lead-acid cells before.

There are great things about low-end cell board systems however: you can have the cheapest product on the market or the highest profit margin and the engineering effort is very limited.

Just something to think about.

[evm1024]

Were you using the HousePower BMS cell boards? I'm not sure if I remember that correctly.

Dimitri stated that you could remove the shunt resistors without any issues on his cell boards.

"No issues with removing shunt resistors. We can do it for you if you mention it in order notes."

regards, Ethan

[toddedger]

Maine Sail, Please share what you find on disabling the shunt on the boards. I think I have the same clean auto power BMS system as you do. I don't see any need to have them be able to ballance. I think I stay out of their ballance range by design, but that obviously isn't enough.

I don't have room on board my little boat to take my bench top power supply and I'm planning some long range cruising. I don't think it would hold up well on the boat anyway. I did purchase spare BMS and cell boards before they went off the market.

[Maine Sail]

Originally Posted by OceanSeaSpray

Boats should use centralised BMS units. With the high charging currents we get, the cell voltages get jacked up early, before the cells are near full, and cell boards can then start shunting and throw the whole pack out of balance. The concept itself is wrong for the application.

This can't physically happen with our system. HVC is purposely programmed before the voltage where cell boards begin shunting. I set it up this way so balancing could be a "manual & attended" event like equalizing a lead acid battery. I quickly discovred however that shunt balancing keeps cells at a high voltage for far longer than a manual parallel balance does so decided that I would not use shunt balancing.

I actually ran a head to head test where I purposely unbalanced a cell then let shunt balancing have a go at it. After more than 20 hours at 3.55V + the cells were still not in balance. I then repeated the same imbalance with the same cells only this time wired them in parallel and pushed them until they wer no longer taking any current. Parallel was multiples less duration spent at a high voltage than shunt balancing required.

If you keep charging until full (when the current has tapered down), then shunt balancers get a chance to correct early errors.

There are no early errors, my charge sources are shut down before shunting can occur, unless of course a cell board fails, and I don't push my cells that high because there is just no need to.

This works when you charge an EV overnight with a perfect CC/CV/Terminate regime and a modest current, but not on boats where we often don't get to the end of the cycle.

If you design the system so that balancing requires manual overrides and human attendance. This is not an issue...


[quote]The fundamental problem is that the cell boards have no idea of the battery current and cell internal resistance. They should only shunt when the current is low and the voltage high, but in reality they will shunt at any current.[quote]

If you program your HVC before shunting, and make it a manual event, this does not happen..

It is such a problem that the shunting voltages are almost invariably set very high, which defeats the purpose.

This will be the first time in well over 800 cycles this pack has been balanced, there has just been no need.

The #1 driver behind cell-board schemes is commercial: you can offer it to everybody regardless of the number of cells. Having intelligent cell boards would require a lot of more than a 1-wire current loop to get a system operating correctly and then the economics are not looking so attractive.
The control unit in a cell board scheme basically has next to nothing in it: it monitors the loop and takes action on 2 or 3 voltage conditions without even knowing where they originated. The HV thresholds are frequently very high so the system stays put when you drop it into an installation that had lead-acid cells before.

There are great things about low-end cell board systems however: you can have the cheapest product on the market or the highest profit margin and the engineering effort is very limited.

Just something to think about.

You talk a good game so why not put your money where your mouth is and we can all move forward... With Dimitri off at Lithionics & out of the game it seems you'd be rolling in the dough....

[Anjin]

Originally Posted by Maine Sail

If I had not yet fully convinced myself that balancing is unnecessary, at the charge voltages I use, I am now

I'm not nearly as experienced as you and certainly not as disciplined in documenting the operation of my system, but I now have a year of running my 8P4S installation (1440 AH) and agree wholeheartedly. All of my charge sources are set to <=13.8 and I regularly check the "individual cells" (8 CALB 180s wired in parallel) with a calibrated VM at "full" charge (i.e. full enough for me as shown by the charge current dropping below 5% of available current). They have never been more than 2 mv out of balance. I've probably gone through several hundred cycles at this point but do not discharge very low - my primary charge is solar so a cycle for me is a normal day and night's use that typically reaches a low at 9AM (typically ~80% charge) and tops up again around 2PM at 100%. I drop down quite a bit lower than that during extended periods of cloudy days or when my wife decides to do a lot of baking in the electric convection oven or when we have a lot of guests that expect to take long hot showers (have to make the water and then heat it, sigh).

This install has changed to way we think about and use the boat. I rarely give power a second thought - just glance at the charge monitor and occasionally check the individual cell voltages. I run the generator every week or so just to give it some hours and try to schedule it for really warm evenings when we can benefit from running the A/C.

The stability of my installation may benefit from the 8P4S configuration - my hypothesis is that any manufacturing differences between individual cells are cancelled out by the 8P wiring.

My solar panels are each wired to their own controller (Victron MPPT) and all controllers are set to 13.8v. My generator goes through a Victron inverter charger and the whole system is monitored by the Victron BMV-700 which has never sounded its alarm. The High and Low voltage monitors that control the charge and load bus cutoffs are managed by an internal programmable voltmeter and latching relays. The high voltage cutoff tripped once but it was because the voltmeter failed and started reading .5 volts high. The only thing I have to be careful about is using the alternators which I consider auxillary or tertiary sources (after the solar and generator). They are unmodified internally regulated hitachi dumb alternators which I normally have switched "off" (but they still charge the lead acid starter batteries) and I may use them when the batteries are down more than 100AH or so and we're motoring. When the batteries are closer to full charge I just leave them off.

I did a very long and careful top balance prior to install. I do not have any automated balancing and have never had to rebalance. I stay out of the debates about whether I am really getting my batteries "fully charged" - they are full enough for my needs. I monitor the voltage levels and the charge state and otherwise am just waiting for any indication that something is amiss.

So far, so good. In fact, so GREAT!

I can't say enough good about the robustness and ease of use of these batteries. I also can't say thanks enough to you and the other contributors on this forum that made it possible.

Cheers

- Art