Lithium Ion Batteries

[DebDav]

Newer technology than AGM.  Interesting specs.

Looking for pricing

http://www.corvus-energy.com/energy_module.html

Anyone tried or heard positives/negatives?

[happycamperbrat]

The only draw back is the expense...... these are usually used on an ev Nice batteries indeed, just very, very costly

[TomC]

Looks like they are made in a 12vdc 420amp/hour case.  I emailed them wanting pricing-but it looks like each "battery" is going to be about $1,000.00 each.  In my case I'd be using two.  They also claim to have a lifetime warranty on the batteries.  The specs look quite interesting.  If the batteries last the lifetime of the motorhome-it would be cheaper in the long run to use these batteries.

Sean-what's your take on these batteries?  Good Luck, TomC

[technomadia]

One of the nicest perks of lithium batteries is that you can actually use your entire battery capacity.  They don't prematurely age when you discharge them over 50% o over 80%.  You can also charge them to "full" a lot quicker - they don't need an absorption phase and can bulk charge until they are at 100%.

There are some downsides though.  Cost and unproven newness being the biggest.

  - Chris // www.technomadia.com

[tpboj]

Here is an article I came across possibly it may give some assistance in evaluating Lithium Ion Batteries
http://www.aboutrving.com/rr_one.php

[belfert]

My understanding is the lithium-ion batteries will get wrecked if discharged below 20% of capacity.  The vast majority of lithium-ion batteries have circuits built-in to cut off the batteries to prevent over discharge.

A friend of mine says his reasearch shows that Lithium-Ion batteries will lose 20% of capacity per year regardless if the battery is used or not.  I haven't verified his claim.  I do have a Makita Lithium-Ion battery that seems to work as good as new after 4 or 5 years.  (I bought the Makita Lithium-Ion right after they came out.)

[luvrbus]

They must cost a bunch of money I see where Marathon and Newell are offering the Ion as a upgrade lol  


good luck

[chuckd]

I worked on electric vehicle batteries at 3M, we used Lithium metal and a solid polymer electrolyte, we could not get around needing to warm the battery in order for the polymer electrolyte to be in a usable state.  Do have some information on our competition in Li ion.  I believe that a full discharge is harmful, but you can go to 20 dod and be okay, and you can do it rather quickly, i.e. lots of power in a fairly short time frame (although not as quickly as a Lithium Polymer battery) They do charge fairly quickly with a great deal of assurance as to what the exact state of charge because of the rather steep and usable discharge curve.  The knock on them in the past for use in EVs is that lose capacity with calendar time not cycles.  This has not been as issue with cell phones and laptops, because we typically replace the entire device before we notice much degradation in performance due to battery issues.  I haven't been in the business for 8 years so perhaps new anodes and cathodes have improved the situation.

LI ion and NiMH batteries love hybrid use as they really like rapid charges and discharge cycles.  Li Ion and NiMH  do not cycle constant watt hours, the capacity is much greater with a hybrid vehicle charge cycle.

Interesting to read the article about rv battery use.  Hopefully they will outlast the agm batteries and become a little more cost effective.  The use of Li Ion in the Leaf, and Chevrolet volt will also help move the batteries down the cost curve.

Chuckd - who is a bit schizo for having worked on green technology while driving a bus the gets 7 mpg - but I can deal with it.

[TomC]

I just talked to Corvus Global about their battery.  The battery is little bit bigger then a 8D, but weighs 140lbs.  It has 500 amp/hours, and 6,000cca, but maintains voltage much longer then a lead battery, then drops off fast.  It can be fully discharged in 6 minutes, recharged as fast as you want, can be FULLY discharged to 0 volts 5,000 times without harm.  They use Lithium Polymer technology.  Each battery has programmable voltage, amperage, cut off voltage cell monitoring.  Instead of using hundreds of what looks like AA batteries, they use 24 individual flat cells that looks like a magazine.  Hence less resistance, no heating problems, less maintenance.  If you keep the discharge rate to no more then 50%, battery life expectancy is around 25 years.  They can be mounted in any position, and can still work submerged up to 10ft.

Now the cost-around $8,000.00 each!!!!

Good Luck, TomC

[chuckd]

Tom, I am not sure how it is now, but 8 years ago when  I was in the business, if a battery developer was moving his lips, he was lying, so be a little cautious with some of their claims.  5000 cycles to 100% dod is something I would have to see, 25 year life @ 50% dod doesn't say much, unless they state cycle life.  Just be cautious.

chuckd

[Sean]

... Sean-what's your take on these batteries?  Good Luck, TomC

Funny you should ask, because I am in the market for batteries, and so I have been looking seriously at lithium (specifically, LiFePO4) batteries.  I do think that lithium holds a lot of promise for the future, but, frankly, the technology is really not ready for the RV industry...

One of the nicest perks of lithium batteries is that you can actually use your entire battery capacity.  They don't prematurely age when you discharge them over 50% o over 80%.  You can also charge them to "full" a lot quicker - they don't need an absorption phase and can bulk charge until they are at 100%.

Yes, but...

There are some downsides though.  Cost and unproven newness being the biggest.

Actually, I think there are three much larger issues.

• Any Lithium technology requires a sophisticated battery management system.  Without it, the cells will be destroyed fairly quickly.  With lithiums, it is not sufficient to have battery management only at the head end of the entire bank; there MUST be electronics at each and every cell.  Tomes have been written on this, so I won't repeat it all here.  The best batteries have such a system built in, as do the ones linked at the beginning of this thread.  But note that each manufacturer has its own, so you can't mix cells from different brands.
• Even with a BMS, lithium cells have a propensity to run away.  This is why they can only be transported as haz mat, can't fly on airplanes, etc..  They do present a much greater danger than AGMs, especially if they will be inside the living space as ours are.
• Absolutely the biggest issue, for us in the RV community, however, is the incompatibility between lithium technology and the charging systems commonly used on RVs.  These banks can't be charged on common lead-acid settings, and even most sophisticated chargers can't handle the profiles for these.  Some chargers like the one in our SW4024 have enough flexibility in the settings to at least approximate the correct profiles, but they are less than ideal.  A lithium BMS with built-in charger is the right answer, but that adds expense to the system and sidelines the chargers many of us have in our inverters.  This also defeats existing generator auto-start systems.  Most importantly, the coach alternator simply can't be used at all for charging these batteries correctly, eliminating the #1 charging source for many of us.

So for us, lithium does not seem to be a viable answer until fully integrated, listed RV inverter-chargers as well as alternator regulators with proper charging profiles are available in the market to work with lithiums and their BMS's.

FWIW, YMMV, etc.

-Sean
http://OurOdyssey.BlogSpot.com

[dougyes]

At a builders show in Orlando, Milwaukee Tools had a old Pontiac GTO converted to electric and run on a trunk full of Milwaukee L-ion tool batteries.
Fill in the blanks:
$8000.00 worth of Milwaukee tools = _______ batteries and _____chargers. Add the free extra battery coupon +________ batteries = ________ total batteries X ______amp hours per battery = _______total amp hours.
$8000.00 - ______ (sell my old tools on Craigslist)= $_______ net battery cost.
After that it's just a wiring issue!
And if it fails I'm left with a shop full of new tools...win win !!!

[HB of CJ]

Thank you all.  Makes me wonder what we will be seeing in just a few short years....some sort of electronic long discharging capacitor or something?  HB of CJ (old coot)

[happycamperbrat]

Im thinking (and hoping) that as more evs are made in the next 10 years that the price of these batteries will drop tremendously......

[pvcces]

Hi, Sean.

I was really glad to see you weigh in on these batteries. I was very concerned about the charging profiles, too.

I studied the graphs that Corvus has on it's site, and I had the impression that the BMS doesn't just report battery condition, it actually controls the charge. According to the graph I looked at, it looked as though the charge was just cut off completely when the battery reached full charge.

That made me think that the charging profile might not be such a problem if the charger produced a high enough voltage to get over the resting voltage of the battery for any given state of charge. It looked as though we wouldn't have to worry about overheating the battery, even if the battery took the full output of 220 amps until it was charged.

As far as the discharge profile is concerned, it didn't look like it would matter unless the resting full charge voltage of the battery was high enough to damage equipment in the coach. AS far as discharging the battery goes, I already know the BMS will shut off the discharge if the battery gets too low.

Do you think that I have this wrong?

Thanks, Sean.

Tom Caffrey