Small LiFePO4 (<100 AH) + Echo Charge for Windlass

[evm1024]

I'm starting to toy with the idea of switching LiFePO4 when my Cofl Cart batteries need replacing. When researching I started to wonder about using a small LiFePO4 battery to power the windlass and (thruster - When I eventually get one).

The twist here is that I have a LA battery in the bow that is charged by an Echo Charge which has a 14.4 V max output and could be a good match to 3.6 V LiFePO4 cells.

I'm interested in hearing if anyone has done this (used an echo charge as a poor mans BMS with out cell level monitoring).

The configuration would be:

Main charge buss to 60 amp breaker
#6 cable runs forward from 60 amp breaker to Echo charge in the forepeak
Echo charge to 60 to 100 AH LiFePO4 battery
LiFePO4 battery to windless via 1/0 cable and 400 amp fuse
LiFePO4 battery to thruster by 1/0 cable and 400 amp fuse

60 amp breaker from #6 cable to 1/0 cable (echo charge bypass - normally off)

Normal operation has the LiFePO4 feeding the windlass and thruster with the echo charge taking care of charging the LiFePO4.

Should the LiFePO4 die or be flat the bypass breaker can be activated which allows the house bank to supply (up to 60 amps) to pull up your anchor (needs low drag to avoid tripping the breaker).

Should the echo charge die the bypass breaker can be activated to allow charging the LiFePO4 from the house bank (and engine alt).

Hopefully this is not too confusing without a schematic.

Is the echo Charge up to it? Will >100 AH LiFePO4 handle no "real" BMS? Comments, thoughts etc?

Thanks

N.B. Tried searching for this to no avail

[Maine Sail]

Short answer is don't....

[SV THIRD DAY]

Originally Posted by Maine Sail

Short answer is don't....

In another post about LiOn batteries/technology Maine Sail stated his worry that LiOn batteries will be given a bad reputation and take the hit when some owners of the technology try taking short cuts and bad things happen. Well.....let the short cuts begin and the disasters to follow.

[evm1024]

The point is well taken about owners taking shortcuts. This is most true with new technologies.

Any new technology comes with various pitfalls that need to be overcome to make the technology safe(er) for backyard mechanic use and abuse. Thus no portable nuclear in our hands. Lead acid has a number of pitfalls that have been overcome to a greater degree (split acid, explosions, fires caused by internal and external shorts etc). Lithium technologies are no exception.

Part of the question is: has lithium battery technology (12v replacement LiFePO4 batteries with internal BMS for example) reached the point where they can be deployed as outlined in post #1?

Here is a link to one vendors implementation:

Stark Power | Lithium Starter Batteries & Energy Storage Batteries

regards

PS I think that Lithium already has a bad reputation. The Lay public if they even know about lithium technology has heard of the fires and explosions ranging from airplanes to cellphones. That is no "real" problem with the adoption as the technology improves and works out these issues. There are significant advantages that will cause the adoption to move forward.

[Maine Sail]

Originally Posted by evm1024

The point is well taken about owners taking shortcuts. This is most true with new technologies.

Any new technology comes with various pitfalls that need to be overcome to make the technology safe(er) for backyard mechanic use and abuse. Thus no portable nuclear in our hands. Lead acid has a number of pitfalls that have been overcome to a greater degree (split acid, explosions, fires caused by internal and external shorts etc). Lithium technologies are no exception.

Part of the question is: has lithium battery technology (12v replacement LiFePO4 batteries with internal BMS for example) reached the point where they can be deployed as outlined in post #1?

Here is a link to one vendors implementation:

Stark Power | Lithium Starter Batteries & Energy Storage Batteries

regards

PS I think that Lithium already has a bad reputation. The Lay public if they even know about lithium technology has heard of the fires and explosions ranging from airplanes to cellphones. That is no "real" problem with the adoption as the technology improves and works out these issues. There are significant advantages that will cause the adoption to move forward.

One look at the charge voltages in that link and it makes me laugh.... Lots of snake oil sales people around every corner.... Run don't walk away from any company that says LFP can be charged at 14.6V...... Stoopid is as stoopid does....

[SV THIRD DAY]

Originally Posted by Maine Sail

Run don't walk away from any company that says LFP can be charged at 14.6V...... Stoopid is as stoopid does....

But it's on the internet...it must be true...just like BigFoot!

[evm1024]

Originally Posted by Maine Sail

One look at the charge voltages in that link and it makes me laugh.... Lots of snake oil sales people around every corner.... Run don't walk away from any company that says LFP can be charged at 14.6V...... Stoopid is as stoopid does....

That site is an example of one that sells integrated BMS 4 cell LiFePO4 12 volt replacement batteries. There are others. These battery makers may have the engineering off but they do have engineering (someone integrated the cells, BMS and case).

There are other charging regimen for LiFePO4 than CC. TI has case one in silicon: http://www.ti.com/lit/ds/slusa66/slusa66.pdf

From the IC datasheet : The LiFePO4 charging algorithm removes the constant voltage mode control usually present in Li-Ion battery charge cycles. Instead,the battery is fastcharged to the overcharge voltage and then allowed to relax to a lower float charge voltage threshold.

So let's look at the system I proposed starting at the battery and follow the chain back to the alternator.

Battery: LiFePO4 12 v replacement battery with internal BMS of a size matched to your windlass and/or thruster needs. Could be up to 90 AH or so. Looks like you could use a 40 AH battery and get by. For example the Vetus 55KGF (4 HP) is speced at 350 amps draw with 4 minutes as the max single run time. So 4/60 * 350 = 23.33 AH. The internal BMS sets over voltage protection and cell leveling. Some do under voltage cutout.

Xantrex Echo Charge sets maximum voltage to 14.4 volts and max current to 15 amps. This assumes that the input voltage is at or above 14.4 volts (plus the echo charge insertion circuit drop). In addition to limiting the voltage and current to the LiFePO4 battery the echo charge allows for a replacement FLA to be used if the LiFePO4 fails in the field. The echo charge follows the main charging system voltage.

MC-612 / alternator charging system: The MC-612 bulk charges at 14.6 volts (with the echo charge limiting the voltage at the LI battery to 14.4). Then it drops to 14.4 for the absorption phase. Finely dropping to 13.35 volt float voltage. Which gives 3.33 volts per cell which is less that the 3.5 volt float voltage specified by the TI chip.

Is it an optimal system? Unlikely. Will it charge to 100%SOC? Rarely but sometimes. Will it effect battery life? Possibly.

Then again we are only likely to be taking less than 10 AH out of the battery when we pull the anchor chain or use the thruster which a 40 AH LiFePO4 battery should handle just fine.

-----------

[evm1024]

I am really hoping that this thread can be given the degree of thought and seriousness that it deserves. There are a number of instances on a boat where a dedicated LiFePO4 battery would be really nice. The windlass example given or how about a dedicated battery right next to your SSB.

It would be nice if there were a COTS BMS for small point of need LiFePO4 batteries that ran off the typical 12 boat system. Something about the size of the echo charge. I do not know of any.

I don't have any experience with LiFePO4 systems but I do have 40 years engineering experience. Perhaps we can look at the idea and see where it takes us.

[Ex-Calif]

What does this mean?

"NOTE:

StarkPower’s “ULTRAENERGY” are to be used for energy storage applications and NOT for engine starting applications with batteries under 20Ah. Do NOT use with high current applications !"

I'd guess a windlass is a high current application?

It's compelling to have "isolated" and dedicated batteries for certain systems on the boat. These guys also make a dedicated charger with (I presume) a proper charge profile.

I think one still has to understand too much to believe the hype on this website.

[evm1024]

The stark power batteries appear to come in 2 variants that I noted. One for deep cycle (not to be used for starting) and starting batteries. One could presume that either cell construction or interconnect (including bms sensing) are "smaller" in the deep cycle batteries.

Stark was just noted as a pointer to LiFePO4 12 v (LA) replacement batteries with internal BMS. (BTW, the stark charger runs off AC)

Looking over cell datasheets (Winston WB-LYP60AHA)I see that a typical discharge impulse current is <= 10CA so for a 60 AH battery that would be 600 A with 3 CA for the constant current discharge rate (180 A).

All that falls in the range of a windlass or thrusters needs. They are high current applications but they are impulse devices. Peak load breaking the anchor out then lower load to lift (assuming you do not use the boats motion to break out). Ditto for the thruster. A few seconds here or there.

[evm1024]

Being a hands on kind of engineer I've ordered 4 Winston WB-LYP40AHA 40 AH cells, a houseBMS and shunts and a few other odds and ends. Putting my money where - These will be the basis for some future posts when they get here....

I've started reading the "House bank" thread cover to cover - it would be nice if you all could post more slowly than I read.

This 40 AH battery will get placed for my windlass battery. I cannot see that my usage will be much of a test. but then again it is an aux battery in a lead acid system. And what I learn there will cover me when I eventually go full lithium. I could also move it to the start battery position as well to try out.

I'll likely be tracing out the schematic of an echo charge with an eye to the possibility of making mods to it to limit voltages to match, better match, the needs of a small LiFePO4 battery.

Regards

[Colin A]

Sterling Powers BCM module claims to adapt a conventional charger to LiFePo4, I have not tried on so not sure how well it works. The documentation states you need a BMS as well. It seems most of the companies going in to the lithium marine market have decided to integrate BMS into the battery rather than a stand alone module. Some of them also seem to have the BMS setup to handle the batteries as a direct drop in (adapting charge profiles etc. Super B seems to do this as well.
http://www.shop.sterling-power.com/acatalog/BCM.pdf

[Maine Sail]

Originally Posted by Colin A

Sterling Powers BCM module claims to adapt a conventional charger to LiFePo4, I have not tried on so not sure how well it works. The documentation states you need a BMS as well. It seems most of the companies going in to the lithium marine market have decided to integrate BMS into the battery rather than a stand alone module. Some of them also seem to have the BMS setup to handle the batteries as a direct drop in (adapting charge profiles etc. Super B seems to do this as well.
http://www.shop.sterling-power.com/acatalog/BCM.pdf

Sadly Charlie does not know the first thing about charging LFP batts but he's now got the "cool" factor by claiming, rather incorrectly, that his products are Li compatible...... If you value your money, DO NOT use the BCM, or any Sterling battery charger on the Li setting to charge LFP batteries, unless of course you want to create PROBLEMS.......

Fortunately the Sterling ProCharge Ultra has a custom setting, which can be used for LFP, the BCM does not....

[hellosailor]

evm-
I try to read between the lines and all the smoke and marketing mirrors that the various "lithium" companies put out.
It seems like the consensus are saying that any of them could be a drop-in replacement for lead, since pretty much all of them use 4 cells rated each for an operating range of 2.8-4 volts, which would allow a "12" volt battery to be safely ranging from 11.2-16 volts. As long as you took proper precautions for low voltage (i.e. with a battery cut-off) you'd be in the safe operating range and in theory, no problem.
Except they also pretty much all say a BMS is mandatory. Possibly because they are not saying, a simple manufacturing defect could cause a cell unbalance leading to fire and explosion or similar exciting events.
So...reading between the lines, you are perfectly safe to drop one in, unless a rare but predictable manufacturing defect or low voltage damage (etc) causes it to explode, which odds would be minimized by the use of a BMS. Which will only double of triple your battery cost.
There is also one company selling drop-in replacement with a BMS "in" the outer case, about $1300 for a Group27 size battery as I recall. Stop laughing!(G)

If you do drop in a lithium battery without a BMS, you might consider at least having a nice battery box welded up out of boilerplate or similar thick metal, just in case there's some reason behind all the talk of a mandatory BMS and risks of excitement.

Boilerplate, lined wire firebrick, just in case it does a China syndrome. Lithium batteries (except LiFEPO4 ?) are a Class D fire hazard, conventional means won't put them out.

Still interested?

[evm1024]

Still interested? But of course!

Being a research engineer at a NSF Regional Science Center by trade gives me (perhaps?) an advantage. I'm still coming up to speed with LiFePO4 but I can see (bits of) the paradigm shift that is needed for their use.

The Jay Whitacre video is quite instructive for a quick overview of the technology. Specifically the physics of LiFePO4 energy cycle. The 100% to 0% charge voltage curve is easily understood once listening to the first 30 minutes of the video or so for example.

Robotics Institute: Videos

The primary risk of fire etc (in LiFePO4) is associated with over charging. Over Drawing the battery down too many times more likely will be a wallet event. Some will argue the safety but that is moot in my mind (plenty of LA explosions with the resulting acid mess) if you stay in the safe operating envelope of the device.

The "drop" in batteries all appear to include an internal BMS but one does not know how effective that is. For my testing I just will use the 4 (40 AH) cells and add the houseBMS for the experience (I'll add an 800 AH house sooner or later). Limiting the upper voltage to the battery to 3.4 v per cell is a function that the echo charge may do well (with a mod). or perhaps I'll make a small charge controller that isolated the battery from the charge bus at 80%SOC (try finding that point! that is the trick). No need to have a low voltage cutout in this application - or so I think right now.

Regards