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

[GoingWalkabout]

[tsmwebb]

The home storage units and EV's are interesting but I'm not sure if it would be easy to integrate their batteries with an existing 12 volt system. Many EV and home Li battery systems are not using LiFePO4. There are many different Li battery formulations. Most of them are nominally around 3.7 volts /cell. In use minimum 2.5v, maximum 4.2v. One of the benefits of Fe when used with an existing nominally 12 volt system is that it's nominal 3.2 volt/cell (~2.5v - 3.6v) means that 4 cells in series operate in at very similar voltages to lead batteries.

[lagoon100]

Hi, i have an offer from Winston factory direkt for the 200ah cells for 220$ & shipping, has anyone ordered form them lately, what about the roomers that they could bankrupt soon?

There productions seams to be going at 100% as the earliest slot the could give me is end May / early June.

Any infos?
regards
Lagoon

[mcarling]

Originally Posted by GoingWalkabout

The batteries are priced at $10,000 for the 4 kWh model up to $24,000 for the 16 kWh model.

That is very expensive. I paid just under $11,000 for 27KWh of LiFePO4. Also might be LiCoO2 (which is not a chemistry I would want to have on a boat) rather than LiFePO4.

[Hoopla]

Most high capacity LFP friendly chargers seem to be only readily available as Charger/Inverter Combos. However people are reticent about using them as a combination as they use a common DC source/supply cable connection which renders either the BMS's HVE or LVE protection useless. In so far as Victron units are concerned there is a workaround.

This workaround can even make older model Victron Multiplus or Quatro Charger/Inverter units very LFP friendly in terms of both AC and DC surge issues and for cell voltage protection.

More modern Multi/Quatro units come with Auxilliary Sensors (potential free contacts that can be configured to operate open or closed) which are connected to your BMS, possibly via a relay(s). The BMS can then turn the Charger/AC side off in the event of a HVE (or just in advance of that if your BMS has that alternator friendly feature). It can also turn the Inverter off for a LVE. This is accomplished using Victron Software Assistant called "Lynx Ion BMS Support. Even those with older Multi's that have no Auxilliary Inputs, the Lynx Assistant can configure the Lead Acid Temp Sense to act as either a HV OR a LV Input switch for the Multi/ Quatro. Unfortunately for the older units not both.

For those with older units email the installed firmware number (chip on main board is stickered or obtain using VEConfigure) and details of your unit to Victron tech support and ask for an appropriate firmware update (which you will flash the board with) that will be compatible with VE Configure 3. Version 3 is required as it incorporates a flat LFP charge curve and is compatible with Lynx Ion Support Assistant to control the Auxilliary Input(s) and work with any sort of LFP BMS.

For older Multi units with only one Auxilliary Input/Temp Sense I advise putting the Multi on the Charge Bus and configuring the Input to enable the BMS to turn the charger off in the event of a HVE. The Multi has in VE Configure 3 a pack voltage setting to turn off the Inverter well in advance of a LVE. As an added precaution on account the Inverter could still drain the battery bank via the Charge Bus simply instal a standalone relay to the Multi that is connected to the BMS's LVE output. The only complexity is that when recharging using the Multi after a LVE, this relay would have to be manualy reset. That would not be necessary if another charge source was first used.

Hope this helps, particularly those with older Victron units.

[exMaggieDrum]

Originally Posted by lagoon100

Hi, i have an offer from Winston factory direkt for the 200ah cells for 220$ & shipping, has anyone ordered form them lately, what about the roomers that they could bankrupt soon?

There productions seams to be going at 100% as the earliest slot the could give me is end May / early June.

Any infos?
regards
Lagoon

I got a quote from them last week for US$1.30/Ah, so higher than the quote you got for $1.10/Ah. I decided not to go with them because they will not ship, or even make arrangements to ship, your cells - terms are EXW from their loading dock. Their cells were my preference. They did not give me an availability date. Haven't heard any bankruptcy rumors - but there have been some in the industry in the past and several lawsuits between manufacturers.

I'm getting Sinoplys from a Canadian distributor (canev.com) but with them you have to order in advance because they aggregate shipments in dangerous goods containers. They said the soonest I could get them were in April, and, they wanted money upfront when I order. Haven't absolutely confirmed that. I'll post updates. They are US$1.30/Ah and come assembled in 4 cell nom. 14v "batteries" with end plates and lifting straps.

[alctel]

Originally Posted by exMaggieDrum

Thanks for your informative posts!

Do you have a photo of your pack construction with the 3mm aluminum plate. It would be helpful.

I was considering using stainless strap to confine the cells but was concerned there would be too much pressure at the corners. I have also seen pictures of some type of plastic banding used. I was thinking of putting end plates that extended past the ends. The obvious problem with any plans I have seen is that the end cells would be much more constrained but the middle units would be able to push out, like Martin's stress analysis shows (nice!). Some kind of significant construction seems necessary to prevent this deformation at the middles. (If needed)

FYI - I have been quoted US $1.45/Ah by a supplier of cells in BC Canada, plus shipping. That includes end plates and lifting straps for each set of 4 cells.

Maggie, I'm also in BC. Which supplier did you look at? I am thinking about taking the plunge this year sometime.

edit: just saw your last post, sigh. If you do go for it let me know!

[exMaggieDrum]

Alctel - Canadian Electric Vehicles Ltd. - talk to Randy, sales rep. Nice guy. They are on Vancouver Island north of Nanaimo.

[Hoopla]

The price of Lithium Carbonate which is mined and used to make Lithium Cobalt batteries has recently sky rocketed in price. This may have a flow on effect to LFP prices, noting exchange rate differences aside, LFP prices have been very stable for quite some time. There has certainly been no evidence yet of the price drops everyone has been hoping to occur.

[exMaggieDrum]

oops - duplicate

[alctel]

Originally Posted by exMaggieDrum

Alctel - Canadian Electric Vehicles Ltd. - talk to Randy, sales rep. Nice guy. They are on Vancouver Island north of Nanaimo.

Thanks! I'm on the island too, so could actually pick them up in person. Will shoot them an email.

[OceanSeaSpray]

Originally Posted by estarzinger

Thanks. So the scooters and forklifts that are using li . . . Are they using a "drop in" system/product (cells and bms etc) or home brew systems? If drop in, what is the approach/product of choice?

In lead batteries, they had the solution well solved in "golf cart batteries" (T105's and related) . . . So if they have the Li solution similarity worked out .. . . Why reinvent the wheel?

Yes, but what you did was taking a 72V (or whatever) forklift, pinch the 6V cells, rearrange them as 12V and hook them up to a system that was already intended for charging such cells.
You didn't actually reuse any of the engineering doing that. There is no comparison.

Now, lithium EV applications are completely different in nature than a marine house bank. EVs are either charged OR used over short cycles, you don't drive off while they are charging etc and when they are charged, it is from a single, dedicated mains power source that was intended for this purpose and there is a high anticipation that they will be discharged again very shortly afterwards.

One consequence of this is that the system architecture required on a boat is quite different and the nature of the use made is also very different in the sense that it is no longer simple repetitive deep cycling in most instances. At present, the "management" of the battery is tightly linked to how you use your system, there is no integrated control at all: integrated management would typically ensure that the battery will last and keep performing regardless of the use made of it.

For these reasons, I can't see some kind of forklift or home system getting transferred and grafted onto a boat (those almost invariably use higher voltage configurations to reduce the amount of current that needs to be handled anyway). Challenges are likely to remain from integrating marine charging systems that weren't intended for anything but lead-acid and others from changes in energy usage profiles that can result in little or no cycling, often "reduced-voltage overcharging" and reduced battery life, which are new issues with lithium.
While these things can be overcome (or ignored if short-sighted) in a given set of circumstances and the benefits extracted anyway, it is not quite the fit-and-forget approach of lead acid batteries. You still need to be aware of a whole heap of new stuff.

Integrated management is what I am interested in, because I see it as the only realistic way of addressing this.

Eric

[OceanSeaSpray]

Originally Posted by scaredycat

This is quite different from most of the other, and more expensive, 400W generators. The typical marine wind generator's charge controller uses 50 year-old technology, which is simply a load-diverter switch, which, upon reaching a set-point, diverts 100% of the energy to a set of resitive elements (essentially heater coils). There are two reason why this is bad and inefficient. The first reason is that when the battery reaches its set-point it isn't actually fully-charged, and this type of Partial State of Charge (POSC) cycling damages the battery by reducing its capacity and sulphating the battery plates. They can't fully-charge the battery because they have no way to dump just the excess power. They can only dump all of it. The best scenario would be to have a way to progressively dump power so the batteries could be fed with only the power that they need at this final stage of the charging process. The second reason that old-fashioned load diverter controls are bad is that even though the set-point has been reached, the wind generator will keep turning, and it does so at full load and at a 100% duty-cycle. So, the wind generator continues to spin with a large load, but is at this point just heating up resistive piles down below..........etc. Read more on their website:
https://store.marinebeam.com/marinek...ind-generator/
It looks like the ducks guts, but not specifically mentioning LiFePO4 chemistry.

Thanks for that. I also received pointers for the Silentwind and D400 units, the little Ampair 100 etc.
You are right, the most basic, simplistic form of control is diverting into resistors or even a short-circuit for some models (which nearly stops the generator), but only some very basic units tolerate this today.
The documentation for the Silentwind states that shorting, or disconnecting under load, will destroy the controller. The D400 seems to perform a gradual diversion into power resistors as the battery charges and they are not happy with the idea of a disconnect either.
Modern wind generators use MPPT converters to match the load to the output curve of the generator.

I am starting to think that a universal strategy with wind generators and LFP could be splitting the output between the LFP bank and starting battery using an isolator. This would allow a proper management system to control the charging of the LFPs by simply disconnecting the wind generator, then leaving it to charge a SLA - what it was intended for anyway.

Some controllers could conceivably "object" to not seeing a battery voltage at all times because of the isolator, but this is merely a supposition.

[OceanPlanet]

Originally Posted by OceanSeaSpray

Thanks for that. I also received pointers for the Silentwind and D400 units, the little Ampair 100 etc.
You are right, the most basic, simplistic form of control is diverting into resistors or even a short-circuit for some models (which nearly stops the generator), but only some very basic units tolerate this today.
The documentation for the Silentwind states that shorting, or disconnecting under load, will destroy the controller. The D400 seems to perform a gradual diversion into power resistors as the battery charges and they are not happy with the idea of a disconnect either.
Modern wind generators use MPPT converters to match the load to the output curve of the generator.

I am starting to think that a universal strategy with wind generators and LFP could be splitting the output between the LFP bank and starting battery using an isolator. This would allow a proper management system to control the charging of the LFPs by simply disconnecting the wind generator, then leaving it to charge a SLA - what it was intended for anyway.

Some controllers could conceivably "object" to not seeing a battery voltage at all times because of the isolator, but this is merely a supposition.

Note that Silentwind has a new controller that can taper the charge current. Also, it can handle a cutoff from the battery (confirmed with them, to be sure) so it is applicable to Li batteries with HVC.

We don't sell them yet...have not been selling windgens as have been too busy already. However with this new controller am thinking to add to our lines. Getting harder to resist...

[OceanSeaSpray]

Originally Posted by OceanPlanet

Note that Silentwind has a new controller that can taper the charge current. Also, it can handle a cutoff from the battery (confirmed with them, to be sure) so it is applicable to Li batteries with HVC.

We don't sell them yet...have not been selling windgens as have been too busy already. However with this new controller am thinking to add to our lines. Getting harder to resist...

Couldn't find any information about a very recent model, so please consider posting the manual if you have one.

In the case of lithium, even crude on/off control is enough to achieve around 80% SOC or more and and it is significantly more adequate than with lead-acid batteries.
It is in fact more adequate that what is obtainable with many more elaborate voltage-regulated units that keep charging indefinitely and invariably overcharge LFPs.

At the moment the manuals for both the 600 and 1000 controller models state: "Please never disconnect the battery wires while the Silentwind Generator is charging. This will immediately destroy the charge controller."

These controllers also detects battery voltage to initialise at power-up, so isolating them from the battery would probably be a no-go. They appear to me as some of the most annoying and problematic for integration with LFPs at the moment (they are complicated without even being smart), so a new model would be rather welcome for sure.

I have sent a few specific questions to the manufacturer and we shall see.