New Battery Technology

[Loredo]

T1 Terry,
I still consider my LTO installation under progress, learning "in the field" about what's needed and what not with these cells. Of course, I have installed leads to check the single cell voltages. Of course, I'm still keeping a close eye on both battery packs. I have just taken both packs apart to check connections and inspect each cell. Nothing to report. It was wasted time. Well not really, like I said I'm still learning. Since the installation of the active cell balancer everything seems to be in the green zone. Time will tell I guess. BTW, I still need to find a good, simple, reliable way to trigger the Heltec balancers. Out of the box, they're always ON. Means, they slowly will discharge the pack. There's a solder pad to undo and then a switch of some sort can be used to turn them on / off. I have yet to decide how to trigger them. For now, I turn the balancers on when I'm on the boat, off when not.
Depending upon the goal, I'm not so sure that the LTO is a really good house battery. My 80AH bow thruster pack needs exactly the same space as the previous 100 AH bank made out of the four optima red tops. I want to replace my house AGM's also and I'd like also like to increase the AH capacity. In this scenario the LTO is a no-no. Using EVE LiFePo cells I could increase the AH fourfold using exactly the same spaces the actual AGM's occupy. Hmmm, still tinkering and sitting on the fence.

[goboatingnow]

Originally Posted by Loredo

T1 Terry,
I still consider my LTO installation under progress, learning "in the field" about what's needed and what not with these cells. Of course, I have installed leads to check the single cell voltages. Of course, I'm still keeping a close eye on both battery packs. I have just taken both packs apart to check connections and inspect each cell. Nothing to report. It was wasted time. Well not really, like I said I'm still learning. Since the installation of the active cell balancer everything seems to be in the green zone. Time will tell I guess. BTW, I still need to find a good, simple, reliable way to trigger the Heltec balancers. Out of the box, they're always ON. Means, they slowly will discharge the pack. There's a solder pad to undo and then a switch of some sort can be used to turn them on / off. I have yet to decide how to trigger them. For now, I turn the balancers on when I'm on the boat, off when not.
Depending upon the goal, I'm not so sure that the LTO is a really good house battery. My 80AH bow thruster pack needs exactly the same space as the previous 100 AH bank made out of the four optima red tops. I want to replace my house AGM's also and I'd like also like to increase the AH capacity. In this scenario the LTO is a no-no. Using EVE LiFePo cells I could increase the AH fourfold using exactly the same spaces the actual AGM's occupy. Hmmm, still tinkering and sitting on the fence.

Yes but the basic characteristics of LTO are way better then AGM ( which I’ve opined are wasted on boats )so even if physically similar it’s a way better battery ie LTO

[Loredo]

There's little doubt that LTO is WAY superior to AGM!

From my actual experience, I'd say it is entirely possible to replace the AGM batteries by simply dropping in the LTO's without changing a dime on the charging system side. The only change, the alternator needs an external regulator (which I already have). It might be possible to even do without balancing with lower discharge amps, but from what I've seen thus far I doubt it. Still the balancing module(s) are inexpensive. For sure I'd do without a BMS.Like I said above, the only "downside" is the LTO's lower energy density. For me it would mean that I'd be stuck with the AH's I have today with the AGM's. I'd like to at least double that.
Decisions, decisions... and boat bucks !

[NPCampbell]

LTO has a number of drawbacks besides cost.

It has roughly the same energy density as AGM so you won't save any space (although it is considerably lighter).

It also has lower cell voltages than LFP but it has the same voltage drop per cell which makes using it in 12 volt system tougher.

If you use a 6s system then normal alternator voltages may not charge it to full. If you use 5s, below around 40% SOC, your voltage drops below 11V.

Due to the wider voltage swing, the power output drops noticeably. With LFP, from 90% to 20% SOC, your voltage drops 3% and your power output drops around 6%. With LTO, from 90% to 20% SOC, your voltage drops 15% and power drops 35%.

[T1 Terry]

Originally Posted by NPCampbell

LTO has a number of drawbacks besides cost.

It has roughly the same energy density as AGM so you won't save any space (although it is considerably lighter).

It also has lower cell voltages than LFP but it has the same voltage drop per cell which makes using it in 12 volt system tougher.

If you use a 6s system then normal alternator voltages may not charge it to full. If you use 5s, below around 40% SOC, your voltage drops below 11V.

Due to the wider voltage swing, the power output drops noticeably. With LFP, from 90% to 20% SOC, your voltage drops 3% and your power output drops around 6%. With LTO, from 90% to 20% SOC, your voltage drops 15% and power drops 35%.

No idea what figures you are using for 90% SOC and 20% SOC regarding voltage, LFP isn't linear when it comes to voltage v SOC. Rested voltage, 2.5vdc is completely drained and 3.5v is 100% SOC, anything in between is a guess, not an actual voltage/SOC relationship, anything less than 3.5vdc rested is not yet fully charged, 3.4vdc rested could be anywhere between 98% and 80% SOC.

Yet to see if this actually plays out in real life. My Gen 2 Prius had a 40Ah 74S1P pack (9.5kWh) supplementing the factory 6Ah NiMh traction battery (1.2kWh), basically topped it up from 50%SOC to 90% SOC when ever there was enough power in the extend range pack. On pure electric drive it could cover 80km @ 80km/h (50mile at 50MPH) The LTO pack will be 55Ah cells 84S1P for a total of 11kWh, 0.3kWh more capacity, it will be interesting to see what range the LTO pack can produce.

T1 Terry

[Loredo]

All true! Yet there are a couple things the LTO battery can do where others are not so good in. Like 10C discharge rate, that's exactly what I needed for my thrusters. Can't do the same with LFO. I did test the 6s fully charged were 42AH, charged with the STOCK alternator the 6S was still 39AH.
Then lets not forget the advantage (= boat bucks savings) that any charge source that's already there for lead-acid batteries can charge the LTO's. The promised extremely long lifespan (only time will tell!) is also appealing. Yet, I'm not so sure I will use them for my house bank for the reasons mentioned in the above MSG.


On edit, I was referring to NPCampbell's MSG but T1 Terry was faster than me in posting

[NPCampbell]

Originally Posted by T1 Terry

No idea what figures you are using for 90% SOC and 20% SOC regarding voltage, LFP isn't linear when it comes to voltage v SOC.

I used 20% to 90% SOC because most people don't bounce their batteries between the extremes. The 100% rested voltage is meaningless because the voltage drops in a non-linear fashion in the first 10% drop in SOC. The bottom end numbers are useless (at least for me) because I have some Garmin gear that kicks off at 11V so I can't let LFP get below 5% and I don't let it get that low because it needlessly lowers cycle life. With a 5s LTO setup my gear would kick off around 30% SOC. I could use a 6s LTO setup down to 0% SOC but then I'd need a boost converter to be able to charge it to full off the alternator.

Originally Posted by T1 Terry

Rested voltage, 2.5vdc is completely drained and 3.5v is 100% SOC, anything in between is a guess, not an actual voltage/SOC relationship, anything less than 3.5vdc rested is not yet fully charged, 3.4vdc rested could be anywhere between 98% and 80% SOC.

I'm not sure what you are getting at here. There are literally hundreds of voltage vs SOC graphs for LFP out there. If you are stating that counting discharged amps is more accurate than cell voltage, then yes, I agree with you. However, the no-load voltage vs SOC numbers from any LFP battery should be fairly consistent over it's life.

[CaptainRivet]

Originally Posted by Loredo

I have replaced the optima red top batteries of both the bow & stern thruster on my boat with LTO.
Background, the BT is a 10KW unit. 100AH @ 24V brand new optima red tops just could not handle the power demand. After a burst of 5 seconds their voltage sagged below 10.5 V. After a 10 second burst they were down to 9ish V. The stern thruster is only 6.5KW but the scenario wasn't much better - +/- the same. It was more or less like, "OK let's get this docking right on the first attempt because there ain't much thrust left for a second one".



BT 12S2P 40AH grade A LTO's.
ST 12S 40AH also grade A.

I'll start saying, the difference between AGM and LTO is night and day.
Of course the voltage sags also with the LTO's but not as much and most importantly only after much longer bursts. (Who needs really long burst from the BT or ST anyway?) The increased thrust due to the higher voltage that's maintained by the LTO's make both thruster much more powerful than with the optima(s).



What attracted me in the LTO's was not needing to change a dime in the charge sources. Plug in and forget... THAT works.
Secondly, a lot of reading later convinced me that no balancing and no BMS would be needed. Well, that's not so true!

The cells got out of balance after only a couple, not even too long, burst.
Out of balance badly! I ended up installing active balancing modules from

Heltec. It's now since February that the system works flawless and honestly I don't feel the need to install a BMS.
No BMS because... where would I find one that could work with a 10KW motor? Then, that last thing I'd want is the BMS shutting down the batteries while I might badly need the thruster. Clear, if I discharge the LTO's too deep too often their life will be reduced. Yet, in this case application even if I get only a 10% of their claimed lifespan, they'll outlast

me, the thrusters, the boat!


Another interesting feature of them LTO's is that their SOC can be predicted perfectly from their voltage. Under a constant load, the sinking voltage is linear with the remaining capacity



I would use LTO also for the house bank but... low energy density and price are holding me back. Even if money was no problem, space on any boat is very scarce and rare.

did you check your alternator how hot it runs? LTO Are very low resistance and suck out all they can get like LFP. on starter not a problem because it's always full, that short starting takes maybe 1-2AH out, so they don't overload the alternator. but a 10kw truster takes out a lot more on a 80AH LTO. Do you have them after a splitting diode like Argo fet From Victron to split the load?
sure with a 10kw motor load on 80AH and 12S you need balancers and a BMS....you are pulling 420A 10C constantly and the startup peak will be above 1000A...25-30C you actually overloading them. you need 12S3P here.
i would just make one bank with 12S5P and done is your house and truster bank, one for all. that's what I done on my former ketch having 12kW bow truster in 12V, in 6S12p.

where you don't need a BMS or a cell monitoring is 6S1P as starter for engines which is typically 1,5 till 3,5kw starter, mostly its a 2kw unit on the 10 hp till 100hp engines. I just used a 712BMV Victron for monitoring total voltage level. that's a 5C, 10C peak load on 6 cells which does not throw them of balance as mild use for them.
on a 3.5kw I would use 6S2P and cell monitoring

[goboatingnow]

I would always recommend a BMS with any lithium ion battery including LTO

[JBP]

Originally Posted by rgleason

https://www.ev-power.eu/LTO-technology/

LTO Lithium Titanate (Li4Ti5O12) Titanate nanotechnology
Lifetime over 20 000 cycles (DOD 80%)
Rapid charge and discharge characteristics
Frequently used in extreme temperature conditions
https://www.ev-power.eu/LTO-technolo...lindrical.html

Wikipedia: "lithium metatitanate ... is a white powder with possible applications in tritium breeding materials in nuclear fusion applications."

I'll install a nuclear fusion reactor as soon as they are available.

[goboatingnow]

I think “ waiting “ for the next battery tech is foolish. There can be a long time for the batteries to
Mature and the support eco systems to become available. ( if ever )

Evaluate today in the context of domain experience , cost and benefits. If it stacks up , buy , if not spend the money on a cruise liner

[CaptainRivet]

Originally Posted by goboatingnow

I would always recommend a BMS with any lithium ion battery including LTO

You don't need a BMS on a 6s1P LTO, waste of money. We put them like this into cars more 10 years ago and no issue at all, for piece of mind you can put a cell voltage monitor. but if you use it as starter in a boat you don't want an LVC event and they can be even discharged to 0V. An HVC can never happen in 6S is only full at 17V which is not even reached when regulator breaks.
yes the 6S1 will be never 100% full but it does not care, you use 38AH of 40AH.

[goboatingnow]

Originally Posted by CaptainRivet

You don't need a BMS on a 6s1P LTO, waste of money. We put them like this into cars more 10 years ago and no issue at all, for piece of mind you can put a cell voltage monitor. but if you use it as starter in a boat you don't want an LVC event and they can be even discharged to 0V. An HVC can never happen in 6S is only full at 17V which is not even reached when regulator breaks.

yes the 6S1 will be never 100% full but it does not care, you use 38AH of 40AH.

I suspect based on ABYC Or ISO insurers will beg to differ.

[T1 Terry]

Originally Posted by CaptainRivet

You don't need a BMS on a 6s1P LTO, waste of money. We put them like this into cars more 10 years ago and no issue at all, for piece of mind you can put a cell voltage monitor. but if you use it as starter in a boat you don't want an LVC event and they can be even discharged to 0V. An HVC can never happen in 6S is only full at 17V which is not even reached when regulator breaks.
yes the 6S1 will be never 100% full but it does not care, you use 38AH of 40AH.

Ummm...... Spend a few minutes and work out the combination of 6 voltages that can reach the end of charge voltage .... it won't take long to realise at least one cell can go over voltage even if the end of charge voltage is less than the perfectly balance cell voltage of say 15v, 2.5v per cell, not fully charged, so the full cell capacity isn't available ......

You can discharge LTO cells with a built in LVC circuit under the cap, cells without this function, do so at your own peril, if the other cells in the 6 cell pack are still above zero voltage, the current will flow in reverse through the fully drained cell, they certainly don't respond well to that treatment ....

T1 Terry

[rgleason]

EnergyX using nanotechnology to improve Lithium extraction.

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