Lithium battery C-rate question

[Jatar]

Originally Posted by AndyEss

As much as land EV use is increasing and can make sense, using batteries for propulsion on a larger boat intended to go to sea seems the height of irresponsibility. As John pointed out, you still would need an ICE for emergency situations - and unless that generator is approximately of the same power as an all ICE propulsion system, it isn't going to provide enough power to keep you moving against adverse currents or seas.

A land EV runs out of juice - you coast to the shoulder and wait for a tow.
A boat runs out of juice - maybe you end up wrecked on the coast.

Keep the ICE engine for propulsion, mount enough solar panels that you don't need to burn dino juice for your regular electrical loads.

Please, let's not turn my simple question about C-Rates into yet another discussion about how a Hybrid Diesel/Electric boat compares to a pure ICE setup. There are plenty of discussions about that in other threads, all of which I have read. Thanks.

[Montanan]

The largest lithium ion battery manufacturers are in China because that is by far the largest EV market and for the major producers the quality is excellent.

15 kw motor operating from 48 volt power supply invokes roughly 312.5+ amperes draw [not counting the significant losses in the system]. You stated motors, plural so multiply that amperage draw by the number of motors. Divide such maximum power by your ampere hour rating of your battery bank and you obtain the ballpark C rating.

You have specified the Oceanvolt, low voltage sail drive product so there is your system limiter. The thermal management [cooling] of those inherently high ampere draw, slow speed, large, heavy motors (motor architecture and specifications constrained by utilizing only a 1.93 gear reduction ratio) would so not be desirable or viable in the commercial EV / "new energy" market sector. Far greater power density and enhanced efficiency could be realized by operating at 10X the voltage source, running a far faster motor and then gearing down to derive high torque, slow rotational sailboat propeller speeds. But EVs have different architectures of their batteries, they favor utilizing much high voltage and accordingly much lower ampere hour capacity which of course is appropriate for high power motorized applications. Low voltage and motors is a poor foundation to start from. Being an executive of an EV propulsion motor development company that works with a major Chinese EV consortium if I were to install electric propulsion motors for marine applications I would strongly prefer 480 volt system over a 48 volt battery, as to making it far easier to provide for the motor controller at the higher voltage. Although you could use a DC to DC power converter to step up the voltage from a low voltage battery pack to provide a higher voltage DC to the inverters to operate the motors, but that would be unnecessary power electronics.

Be absolutely sure to properly wire both the series and the parallel configurations otherwise you will severely unbalance and degrade the 12 V modules of your 48V, 480AH system. Seen far too many a DIY battery bank improperly configured and unsafely wired with inherently adverse results as to realizable power capacity and as to life cycle expectations.

FYI.

Super B has recently merged with Lithium Werks, a Dutch company with its U.S. offices in Austin, Texas, that earlier in 2018 acquired battery producer Valence Technologies Inc. and certain battery manufacturing plants from the failed A123 Systems.

Also, Dutch energy storage and battery company Lithium Werks B.V. (www.lithiumwerks.com) and Chinese Zhejiang Jiashan Economic and Technological Development Zone Industry Corporation have signed a framework agreement with the intention to construct a 60 hectares battery gigafactory in the Yangtze river Delta. Total investments required are estimated at EUR 1.6 billion.

The Lithium Werks factory and related facilities will produce battery cells for lithium-ion batteries, enabling the energy transition from fossil fuels to clean energy in order to reduce CO2 emissions.

"With our Chinese partners' help, and as we continue to grow both organically and through acquisitions, we will deliver the energy storage solutions that our customers increasingly ask for as the world transitions to clean energy," said Koolen.

The agreement, which was signed in the presence of the Chinese Premier Li Keqiang and Dutch Prime Minister Mark Rutte, marks the start of Lithium Werks' plan to build multiple gigafactories across the world as part of a 15-to-20-year program that mirrors the long-term business models of the wind and solar industry.

Lithium Werks expects its revenue to exceed $1bn by 2020 as it continues to grow its share of the rapidly expanding market for energy storage.

Good luck and be careful.

[Jatar]

Originally Posted by Montanan

Be absolutely sure to properly wire both the series and the parallel configurations otherwise you will severely unbalance and degrade the 12 V modules of your 48V, 480AH system. Seen far too many a DIY battery bank improperly configured and unsafely wired with inherently adverse results as to realizable power capacity and as to life cycle expectations.

Where did I say this is a DIY setup? People keep making assumptions. Should I go with a Hybrid/Electric propulsion system, I will not be wiring any of this, everything will all be done professionally. I was simply asking a question about C-Rates for my own edification and curiosity.

[Jatar]

Originally Posted by Montanan

You have specified the Oceanvolt, low voltage sail drive product so there is your system limiter. The thermal management [cooling] of those inherently high ampere draw, slow speed, large, heavy motors (motor architecture and specifications constrained by utilizing only a 1.93 gear reduction ratio) would so not be desirable or viable in the commercial EV / "new energy" market sector. Far greater power density and enhanced efficiency could be realized by operating at 10X the voltage source, running a far faster motor and then gearing down to derive high torque, slow rotational sailboat propeller speeds. But EVs have different architectures of their batteries, they favor utilizing much high voltage and accordingly much lower ampere hour capacity which of course is appropriate for high power motorized applications. Low voltage and motors is a poor foundation to start from. Being an executive of an EV propulsion motor development company that works with a major Chinese EV consortium if I were to install electric propulsion motors for marine applications I would strongly prefer 480 volt system over a 48 volt battery, as to making it far easier to provide for the motor controller at the higher voltage. Although you could use a DC to DC power converter to step up the voltage from a low voltage battery pack to provide a higher voltage DC to the inverters to operate the motors, but that would be unnecessary power electronics.

Also... this thread was also not intended for a discussion on whether the 2017 DAME award winning Oceanvolt SD 15 servoprop system, which won for "Machinery, propulsion, mechanical and electrical systems and fittings", is a good option or not. You can take that up with the judges at The DAME Design Awards, the largest marine competition of its kind, anywhere in the world.

I just asked about C-Rates

[AndyEss]

Originally Posted by Jatar

Also... this thread was also not intended for a discussion on whether the 2017 DAME award winning Oceanvolt SD 15 servoprop system, which won for "Machinery, propulsion, mechanical and electrical systems and fittings", is a good option or not. You can take that up with the judges at The DAME Design Awards, the largest marine competition of its kind, anywhere in the world.

I just asked about C-Rates

If you want a closed forum, hire yourself an EE instead of asking an open, diverse population of sailors.

Your rudeness is noted and your future questions will be properly not considered.
Enjoy.

[Jatar]

Originally Posted by AndyEss

If you want a closed forum, hire yourself an EE instead of asking an open, diverse population of sailors.

Your rudeness is noted and your future questions will be properly not considered.
Enjoy.

Pardon me for attempting to keep a thread on topic... horrors!

[Montanan]

My apologizes, no offense intended, I wasn't stating that your system will be a DIY setup. I am just cautioning that it be done right as far too many battery systems are not properly designed on boats because electrification on recreational boats, e.g., sailboats is comparatively new as to having large house battery banks. Some production boats direct from the factory are not properly optimized as to their battery configurations, the industry is still adapting.

I would expect [or hope] that you would have professional designers and installers as the cost for a system is going to be high in a one off arrangement.

Oceanvolt offers a complete integrated SD15 propulsion system [including a 14kwh battery pack] for Euro 35,292 which comes with a rather short warranty of 2 years from certificate of installation or 2.5 years from delivery. Third party components are warranted only to the extent of their respective OEM warranty, not an Oceanvolt warranty for the integrated system package.
If I was to purchase such, I would negotiate longer terms for the warranty, say 5 years, non-prorated for duration and for more than just the replacement components, it should include replacement labor and shipping, with exceptions as to service performed at remote locations. When a firm will not stand behind their products, one has to have serious reservations. You are dealing with an electric recreational boat which will inherently have modest hours of motorized operation, or they could put an hour gauge on the system and warranty say, 5,000 hours of use.

By comparison and way of example, using Batterypete as an online reference retail example,

Super B – 12v Lithium Battery (LiFePO4) – SB12V160E-ZC 12V 160 Ah
$ 3,279.00 each

12 batteries @ $3,279.00 each is $39,348 for 23 kwh. And that is just the batteries.

I suspect that there are more favorable retail prices then this exemplary one which I pulled randomly from the web, or at least I hope so. That cost per kwh is rather onerous. By comparison, mainstream EVs are presently below $150 kwh and are expected to cross below $100 kwh by 2022 for their high voltage, high ampere hour battery packs.

As to the modest powered SD15 saildrive, it may be "best in class" and will no doubt get the job done for the specialty application of pushing the modest power requirements of a displacement sailboat. But it just isn't in the same league as commercial EV grade of motors and drive systems. It is a slow motor hence large and expensive. The eMarine market is tiny, hence very little development and commercialization effort has been brought to play in this sector. And thus economies of scale of production and spreading of non-reoccuring engineering costs can not yet be derived to realize favorable costs in the eMarine sector. Wish the eMarine sector was not so onerously priced.

But as we know, all things that are specialty marine are comparatively $$$ and eMarine is presently $$$$ or $$$$$.

Happy sailing, and enjoy the quietness of real motors and the lack of diesel fumes when [I]motor[I]sailing.

[john61ct]

Originally Posted by Jatar

I just asked about C-Rates

You are perfectly justified in trying to keep **your** thread to a specific topic.

But in practice easiest to just extract the info of value to you, say thanks and move on, just ignoring those that are off-topic.

Members will often continue to natter on and argue with each other, sometimes for many hundreds of posts and weeks longer, after OP has departed.

[BigBeakie]

Jatar,

Have you considered the Valence U27-24XP series, as an alternative to the Super B?

We were recommended by OV tech to use them after OV tested and gained experienced with both brands. As I understand it, Valence have superior C-rate performance and do not have the internal BMS discharge of the Super B.


Sent from my iPad using Cruisers Sailing Forum

[Montanan]

Originally Posted by BigBeakie

Jatar,

Have you considered the Valence U27-24XP series, as an alternative to the Super B?

We were recommended by OV tech to use them after OV tested and gained experienced with both brands. As I understand it, Valence have superior C-rate performance and do not have the internal BMS discharge of the Super B.


Sent from my iPad using Cruisers Sailing Forum

Now that Super B and Valence are both owned by Lithium Werks, I suspect that their product line will evolve to become similar in offerings. Lithium Works has acquired the industrial division of A123 and its cell production facility in China. My understanding is that the lithium iron phosphate cells are made at the formerly A123 Chinese factory and then shipped to the respective battery module production facilities of Valence made in the USA and Super B made in Holland. Both A123 and Valence having gone into bankruptcy in 2012 and emerging in 2013. Wanxiang a major Chinese lithium battery manufacturer purchased the majority of A123s assets in January 2013. Super B has long been a customer purchasing cells from A123. Wanxiang now having sold the A123 cell production facility and the patent rights to A123 LFP technology to Lithium Werks.

[Montanan]

Back to the C rate discussion.

The Super B battery pack specified would be 23kwh, the saildrive is rated as 15kwh, figure with say 16.5 kwh full power draw factoring system inefficiencies at full power. Therefore 16.5 divided by 23 = about .7 c rate.

That is assuming that you are using the full power of the saildrive, if hull speed and conditions doesn't require utilizing full power then you could draw less. 15kw may not provide for attaining full hull speed, depends on the boat and the conditions.

So then using the quick C rate estimate, for ballpark calculations figure around 1.4 hours of operation at full throttle with your larger battery pack capacity.

Whereas Oceanvolt's packaged system for the SD15 provides for 14kw battery so you would be looking at say 50 minutes of full throttle operation.

Those are rough numbers, real rough but could give you a gauge for emergency planning.

End of charge voltage for the battery is 14.6, voltage drops to 12.8V at 50% SOC when discharging at 0.2C, [note: full throttle will be draw several times higher C rate hence a lower output voltage at 50% State of Charge]; end of discharge voltage is 8 volts. So the C rate varies with SOC and of course the DC voltage supplies to your motor's inverter hence the output power and thus speed at full throttle will vary. There always being a number of variables to factor, never a clean answer with EV systems.

All the best.

[Cpt Pat]

The biggest enemy of longevity of LFPs (assuming no charge/discharge SOC abuse) is heat. Running the batteries at 3C will generate heat. Maybe a lot of heat. I suggest bench testing every cell individually with a good IR thermometer, running the batteries for some time in their actual thermal environment (mounting), and terminating the test once the battery temps reach 50 degrees C at the hottest cell (at 25 degrees C ambient temp). That would be my "maximum military power" setting. Adding forced-air cooling can raise this rating. I'd start the cooling fans at 35 degrees C.

I've seen an implementation where the cells were immersed in transformer oil with a heat exchanger. If you consider this, make sure the plastic cases are compatible with the oil. Still, the center of the cells will be hotter than measured at the outer case, because of thermal resistance. If these are really well engineered cells, the manufacturer should have a number for center-cell-to-case thermal resistance (measured in degrees C per watt).

Cell balancing will be critical. The challenge increases in proportion to the rate of charge/discharge.

[Cpt Pat]

...personally, I'd use salvaged Tesla cells. They were designed to tolerate high discharge/charge electric vehicle use. Cooling them would still be a challenge.


Make sure they aren't damaged. They can catch fire long after an accident.


https://electrek.co/2018/12/19/tesla-model-s-fire-towing/
http://www.ktvu.com/news/tesla-battery-reignites-days-after-deadly-crash-2-investigates

[Montanan]

Originally Posted by Jatar

I won't be using cheap Chinese batteries. I'm currently interested in quality batteries made in the Netherlands (SuperB) or batteries made in Norway(Corvus). Both are expensive but are highly rated batteries.

I'm partial to the Orca ESS batteries from Covus, but I'm not sure they will sell to me (they tend to outfit very large ships, ferries, tug boats, etc.) Though they do list 'yachts' in their applications and do say they offer down to 50v and 5.7 kw batteries. We'll see.

I want to buy a 30kw, 48-volt bank. I've sent them an email to see if they are amendable.

The Super B battery modules are assembled in Holland and made with cells produced in China, specifically, from A123 which industrial division was sold recently by Wanxiang to Lithium Werks.

Lithium Werks purchased Super B in September 2018 and then it was reported to have divested Super B in January 2019. Go figure????? Lithium Werks and Super B are headquartered in the same city in Holland and supposedly are keeping close relationships. Prior to Lithium Werks acquisition of Super B, the two companies had entered into a multiyear supply relationship whereby Lithium Werks via its subsidiary A123 would continue to provide Chinese made cells to Super B. Super B being a longtime customer of A123. Valence is a subsidiary of Lithium Werks. Lithium Werks, Valence, A123 and Super B all use LiFePO4 chemistry.

As to the Corvus battery pack manufacturer, they are stated to be the leaders in eMarine Energy Storage Systems. If I recall correctly they presently primarily utilize cells produced by LG Chem. [Supply relationships have a tendency to change frequently]. Corvus makes large battery packs for large marine applications, such as ships, work boats and dockside hybrid drive cranes that load and unload containers. Apparently presently they have the only lithium battery Type approved by DNV-GL, Lloyd’s Register and ABS.

By way of example of their specifications:
A 1100V STANDARD BATTERY PACK
Energy 125kWh
Voltage Max: 1100 VDC Nominal: 980 VDC Min: 870 VDC
Cooling Forced Air/ Liquid Cooling
Weight 1620kg (3571lb)

FYI, per Corvus:

"The Corvus Energy lithium ion batteries are based on a LG Chem's patented Nickel Manganese Cobalt (NMC) Polymer chemistry. NMC Polymer provides approximately 25% more energy and power density compared to Lithium Iron Phosphate (LiFePO) formulas. When combined with the ultra low internal resistance of the cell, the batteries provide a much higher usable power source that may be used to replace diesel scale power in many industrial applications.
Unlike others in the industry, Corvus Energy has integrated passive cell balancing in the battery as a standard. Cell balancing provides peak performance of the battery system and maximizes system lifespan. Passive balancing eliminates complex and potentially unsafe active balancing systems as a potential risk of fire or failure.
The Corvus Energy Storage System is based upon a 50V standard module (50V at 150Ah). This module may be connected in series up to 1050V as required by the customer. Standard capacity is rated at 6.5 kW-hr nominal. 96V 75Ah modules are available in limited quantity runs."

The Corvus 50V - 150Ah battery module would seem to be a prospective platform for the OceanVolt motor drives.

[john61ct]

Toto, I think we're not in Kansas anymore.

Whole 'nother level. . .