Lithium Batteries

[malcoll]

I've read a ton of material on lithium batteries, and still contemplating the switch over, but I gotta say I'm not q00% sure I what do dive I to this and make all the updates to inverter/charger and BIRD, solar...etc..  Our coach is a 2003 Windsor, two a/c systems,  three a/c units, a convection microwave and a residential refrigerator.   I have 5 solar panels 135 watts each...and a TRACE inverter/charger (I believe it is the oroginal).  I have 8 6v 225ah batteries now...how many 100ah Li batteries should I purchase

[timaz996]

Go to will prowse YT channel and search though his videos and you will learn a lot. 

[cbr046]

I would buy one big battery vs managing several 100Ah batteries.  I have a 300Ah Vatrer on the way . . . . I seem to recall 4 GC2 batteries have 360Ah of life, but GC2s should only be discharged to 50% SOC (state of charge) vs 90% discharge for LiFePO.  I chose this one because it has Bluetooth built in and self-heating for the Winter months.    Vatrer, LiTime, WattCycle and Epoch seem to be well built (per Will Prowse - https://www.youtube.com/@WillProwse).  Maybe others also.  He does a lot of reviews.

There's a ton of education through this thread. 

Good luck with your hunt.

- bob

[Rocketman3]

I agree - look at DIYSOLARFORUM (Wil Prowse’s site - lots of good info and help there - I am on there a lot too.

Batteries:

1. Make sure they have Bluetooth or another way to access cell voltage data, if the batteries get out of balance then you can know it and you can take steps to fix it and know when it’s fixed.

2. Cold Temps - Verify that the battery has low temperature protection/charging cutoff. Almost all do these days - but verify it.

3. Heated batteries… You don’t have to have heated batteries, but I would on an RV - unless they will be installed in a heated area. Lots of ways to do this - so if the battery you like doesn’t have a heater - you can add one externally. 

Here are some things to get figured out it putting in Lithiums… (and before you buy).

Each 2pk of GC2 batteries usually has 225ah of power. So w/6 batteries you had 675ah and 50% usable means about 340ah to 400ah available. In an RV you don’t want to use 100% - 90% max maybe 75%. So you will want at least 400ah minimum- probably at least 500ah - if you choose to have the “same” useable amount. So Lithiums with somewhere between 300ah and 840ah. (That’s two 420ah batteries).

BMS - the BMS on the battery will give the amount of amps it can deliver- 100a or 150a or 200a are the ones I have seen. You will need at least 300a to power your inverter. Two batteries in parallel w/ 150a BMS’s will work - two batteries with 100a BMS’s will cause you issues.

Fewer bigger batteries will be better than LOTS of 100ah batteries. If you have more than two batteries- get a bus bar to connect all the batteries to - with equal length wires - Look at a Victron PowerIn. It does that very well.

Charging… You MUST have at least one charging source that can charge the batteries exactly how they want to be charged - so the BMS has an opportunity to balance the cells. Your Trace inverter/charger may have a setting that can charge them ok - make sure the temperature compensation is turned off!!! With Lead batteries as it gets cold the charger increases the voltage. This can ruin the Lithiums if very cold and increase charge time if hot. Also it will try to charge the batteries when they are below 32F. If lithium’s get charged below 32F - it will ruins them.  My Trace inverter was giving me issues when I bought the rig - so I replaced it with a Victron Multiplus 12/3000 2x120v.   I also have Victron mppt solar charge controllers for my solar arrays. You can set the exact voltage you wish with them too. (Yes I love my Victron equipment).

For charging I make sure all my chargers can’t charge below 32F AND the battery has cold charging protection AND a heater. I want to make sure more than one thing needs to fail before I have a problem- (belt and suspenders).

In my rig, 544ah 12v Lithium battery, 1500w of solar (+ 100w for chassis), I can run one AC (with a Microaire Softstart) for about one hour with a full battery - then I need to decide if I want to start the generator or turn it off. RV Air Conditioners do not work a long time on batteries. But I can run all our lower devices (residential refrigerator, phone adapters, Starlink, computers, etc) and one large item - Microwave, hair dryer, electric water heater, air conditioner, block heater, at a time. If more is needed at once - that’s what the generator is for.

Also, you will probably need to disconnect the alternator charging of the House Lithium bank. I broke that connection then added a Victron Dc-Dc charger to charge from the alternator.

Lithium’s are NOT a drop-in battery in our rigs. There is a bunch to understand and change so you don’t kill the battery and it works like you want it too.
 

Done right they are great - my Lithium’s are almost four years old of full- time 24/7/365 usage - we boondock most of the time. I run my generator less than 100 hours a year. And in four years I have had very little battery fade (I test annually).

Good Luck and let me know if you have any questions.

(Sorry for the long novel).

Edited November 30 by Rocketman3
Fix typos

[malcoll]

Thank you Rocketman!  Great info...I have a lot to consider!

[96 EVO]

On 11/29/2024 at 11:38 AM, cbr046 said:

  I seem to recall 4 GC2 batteries have 360Ah of life, but GC2s should only be discharged to 50% SOC (state of charge) vs 90% discharge for LiFePO. 

Little low! My 4 GC2's are rated at 470AH.

[cbr046]

16 hours ago, 96 EVO said:

Little low! My 4 GC2's are rated at 470AH.

Ooops . . . . and it's too late to edit my original quote. 

Here's hoping my new 300Ah battery will perform as well as lead acid by going deeper into the charge. 

- bob

[wamcneil]

On 11/29/2024 at 12:53 PM, malcoll said:

… I have 8 6v 225ah batteries now...how many 100ah Li batteries should I purchase

How long do you want to be unplugged? Measure or estimate your loads over that period of time and make a decision based on that.
Right now you effectively have about 450 amp-hours at 50% discharge. You’ll get similar capacity with about 400 amp-hour lifepo4 batteries. 

Personally, I wanted to be able to run the residential refrigerator and other base loads for 2-days without sun.  So for me that equated to about 400 amp-hours. 

[Benjamin]

Another factor that complicates the calculation is the charge speed of Li, they can charge at a C1 rate, if not fully charge in an hour, they can often go from 30%-80% in half an hour if you have enough charging capacity.  That's where a big dumb charger has an advantage, even if it will never properly balance Li, it will charge at max capacity until mostly full, so that can dramatically lower generator run time compared to the same AH capacity of lead acid batteries.  If you have alternator capacity and a way to manage that, it can increase the charge you get off running the engine also.  It's less important with solar charging, but even then, if you cycle the batteries throughout the day, like cooking lunch, or watching TV through a cloudy spell, the charging rate can make better use of solar than lead acid can, especially toward fully charged. 

[Tom Cherry]

On 11/29/2024 at 1:53 PM, malcoll said:

I've read a ton of material on lithium batteries, and still contemplating the switch over, but I gotta say I'm not q00% sure I what do dive I to this and make all the updates to inverter/charger and BIRD, solar...etc..  Our coach is a 2003 Windsor, two a/c systems,  three a/c units, a convection microwave and a residential refrigerator.   I have 5 solar panels 135 watts each...and a TRACE inverter/charger (I believe it is the oroginal).  I have 8 6v 225ah batteries now...how many 100ah Li batteries should I purchase

Do the MATH.  You have a total of 450 Amp Hours of capacity.  The TWO 6 VDC batteries are in series....for 12 VDC.  That is STILL only 225 Amp Hours.  BUT, you have TWO banks of TWO in Series.  SO....you add the AMP HOURS.  That is 450 Amp Hours...

You need FOUR 12 VDC (not 6 VDC) 100 Amp Hour batteries.

NOW, you say a lot of research.  Did you search here.  There are MORE posts on this than one can imagine.

There are THOSE that say...  NO ISSUES....use what you got.  In reality, your Trace is living on borrowed time.  It is OLD.  We are seeing MORE inverter failures, both Trace and Magnum for several reasons.  ONE, the electronic or MAIN PCB boards are dying.  WHY.  OLD AGE...but the REAL REASON.  The MAIN CHIPS that do the "INVERTERING" are over heating.  The CHIPS were originally "GLUED" or used a Thermal Heat Transfer Compound.  The Chips sit on a HEAT SINK.  It is FINNED.  The Heat Transfer compound was 100% efficient (or close)...so the CHIP's HEAT was transferred to the Heat Sink.  The fins have a fan blowing over them.  SO, the heat was dissipated into the cabinet and out the vents.

As this Heat Sink Compound ages...it start to CRYSTALIZE.  It is NO LONGER 100% Efficient.  Opinions and research varies....but generally, the CHIPS are overheating.  Most of us turn DOWN the CHARGING RATE...to preserve the CHIPS.  BUT, this is solution with a DROP DEAD DATE.  Eventually, the CHIPS will overheat....especially when it is hot and the doors to the Inverter are closed.  SOME folks install supplemental fans with thermostats to help circulate and dissipate the heat.

SO....when the INVERTER DIES....the fix is ... REPLACE,.  YES, there are folks that can DESOLDER and REMOVE the CHIPS and then RESEAT or REPLACE the Thermal Heat Sink Compound with new.  BUT, there are other, many other, components on the board.  There are sensors and also fans and such.  The Trace also has NO REPLACEMENT REMOTE.  Many have scrounged and found them and they are not cheap.  A NEW BOARD is probably half the price of a NEW inverter....so that is not a cost effective solution.

BOTTOM LINE...your INVERTER will fail.  NOW....will it kill or overcharge or undercharge your EXPENSIVE Lithium Batteries.  We have had a LOT of OMG>>> I destroyed the batteries.  

MOST of the KNOWLEDGEABLE and WELL RESEARCHED folks that convert to Lithium purchase NEW VIctron Inverter.  In you case, you need the DUAL IN...>DUAL OUT system as you have a Subpanel.  SO....if it were me...and THIS WILL BE COVERED AT THE GATHERING>>>>I am working on a presentation that covers most to the electrical...including Lithiums....  MOST put in a NEW inverter.  The Inverter is in the $1,200 range.  IF I EVER UPGRADED....I would do it that way.  My 15 year OLD Magnum will no longer charge at 80 or 90% on hot days without the CHIPS (FETS) getting too hot.  SO, I have turned them down.  I would NOT risk destroying a bank of expensive, high quality Lithiums with my inverter...

I would purchase an INVERTER that is specifically designed for LITHIUMS and has been test and proven.  MOST DO IT HERE.

YES...some have done it with the old inverters...but they are very knowledgeable and KNOW what to look for and how to monitor.

This is NOT A PLUG AND PLAY for someone that does NOT understand the idiosyncracies of the Lithiums....

Personally, I am NOT a fan of YouTube when we have the REAL WORLD and PRACTICAL KNOWLEDGE of our experienced members.

Here is the search.  There are 29 pages.  You will find....that the one that were successful...and there are exceptions where experienced members succeeded....but for the MOST PART...the GONNA GET LITHIUMS and NEVER WORRY AGAIN....then either didn't post or their comments are all the same.  KILLED MY EXPENSIVE BATTERIES...WHY...

https://www.monacoers.org/search/?q=Lithium&quick=1&type=forums_topic

[cbr046]

The better LiFePO batteries have overcharge protection, good protection, so if the inverter goes haywire and tries to zap the battery the BMS (battery management system) will shut down before damage occurs.  Will Prowse has demonstrated this numerous times through his video channel. 

That will be my strategy, anyway. 

- bob

[hitechpete]

On 11/30/2024 at 5:16 AM, Rocketman3 said:

I agree - look at DIYSOLARFORUM (Wil Prowse’s site - lots of good info and help there - I am on there a lot too.

Batteries:

1. Make sure they have Bluetooth or another way to access cell voltage data, if the batteries get out of balance then you can know it and you can take steps to fix it and know when it’s fixed.

2. Cold Temps - Verify that the battery has low temperature protection/charging cutoff. Almost all do these days - but verify it.

3. Heated batteries… You don’t have to have heated batteries, but I would on an RV - unless they will be installed in a heated area. Lots of ways to do this - so if the battery you like doesn’t have a heater - you can add one externally. 

Here are some things to get figured out it putting in Lithiums… (and before you buy).

Each 2pk of GC2 batteries usually has 225ah of power. So w/6 batteries you had 675ah and 50% usable means about 340ah to 400ah available. In an RV you don’t want to use 100% - 90% max maybe 75%. So you will want at least 400ah minimum- probably at least 500ah - if you choose to have the “same” useable amount. So Lithiums with somewhere between 300ah and 840ah. (That’s two 420ah batteries).

BMS - the BMS on the battery will give the amount of amps it can deliver- 100a or 150a or 200a are the ones I have seen. You will need at least 300a to power your inverter. Two batteries in parallel w/ 150a BMS’s will work - two batteries with 100a BMS’s will cause you issues.

Fewer bigger batteries will be better than LOTS of 100ah batteries. If you have more than two batteries- get a bus bar to connect all the batteries to - with equal length wires - Look at a Victron PowerIn. It does that very well.

Charging… You MUST have at least one charging source that can charge the batteries exactly how they want to be charged - so the BMS has an opportunity to balance the cells. Your Trace inverter/charger may have a setting that can charge them ok - make sure the temperature compensation is turned off!!! With Lead batteries as it gets cold the charger increases the voltage. This can ruin the Lithiums if very cold and increase charge time if hot. Also it will try to charge the batteries when they are below 32F. If lithium’s get charged below 32F - it will ruins them.  My Trace inverter was giving me issues when I bought the rig - so I replaced it with a Victron Multiplus 12/3000 2x120v.   I also have Victron mppt solar charge controllers for my solar arrays. You can set the exact voltage you wish with them too. (Yes I love my Victron equipment).

For charging I make sure all my chargers can’t charge below 32F AND the battery has cold charging protection AND a heater. I want to make sure more than one thing needs to fail before I have a problem- (belt and suspenders).

In my rig, 544ah 12v Lithium battery, 1500w of solar (+ 100w for chassis), I can run one AC (with a Microaire Softstart) for about one hour with a full battery - then I need to decide if I want to start the generator or turn it off. RV Air Conditioners do not work a long time on batteries. But I can run all our lower devices (residential refrigerator, phone adapters, Starlink, computers, etc) and one large item - Microwave, hair dryer, electric water heater, air conditioner, block heater, at a time. If more is needed at once - that’s what the generator is for.

Also, you will probably need to disconnect the alternator charging of the House Lithium bank. I broke that connection then added a Victron Dc-Dc charger to charge from the alternator.

Lithium’s are NOT a drop-in battery in our rigs. There is a bunch to understand and change so you don’t kill the battery and it works like you want it too.
 

Done right they are great - my Lithium’s are almost four years old of full- time 24/7/365 usage - we boondock most of the time. I run my generator less than 100 hours a year. And in four years I have had very little battery fade (I test annually).

Good Luck and let me know if you have any questions.

(Sorry for the long novel).

I would be totally shocked to find a 2003 Inverter of any brand able to charge LiFePO4 batteries correctly.

[Tom Cherry]

54 minutes ago, hitechpete said:

I would be totally shocked to find a 2003 Inverter of any brand able to charge LiFePO4 batteries correctly.

AU CONTRE.  It will charge.  BUT, will it charge PROPERLY and within the "NEEDED PARAMETERS" of your expensive Lithiums.  The older Trace MAY work and some say OK in the AGM....but that is a the RISK.  The Older Magnums had an AGM setting, but Magnum often cautioned that "IT WAS A GUESS".

In reality, Magnum has said....many time....I have called and talked to them to "LEARN" that only the NEWER ones are really "Rated" or designed for Lithiums.  They always offer a CAVEAT that the AGM might NOT work.  YES...we have several knowledgeable folks that use them.  

BUT the issue is...  When (not IF) will the Older 20 or 15 Year Inverters start to FAIL.  We are seeing that now.  The Remotes are also an issue.  Trace has NONE to replace it...and folks are fortunate to find USED, and hopefully functional ones.  Magnum has replacements. Having had my Remote fail after 10 years and the "CONFIGURATION SETTINGS" get scrambled intermittently gives me a LARGE CAUSE FOR PAUSE.  Mine was, per Magnum, a TYPICAL FAILURE.

The AMP HOUR settings would go all over the place.  225 to 450....and USUALLY to 1050.  YEEOUCH.  Then, the Battery Type (Flooded) would swap around to AGM.  Now, if one was using, and HOPING, that the AGM setting was OK...and then the Remote FAILED....and it was FLOODED....GOOD BYE LITHIUMS.

This is my ONLY practical concern for members.  The Members that routinely monitor and watch and KNOW what is going on are usually successful with OLDER inverters. However, those that view LITHIUMS as "PLUG AND PLAY AND FORGET" and don't have sufficient knowledge to understand the pitfalls and the disasterous results of OVERCHARGING that expensive investment.....  That is WHY I am "labeled" as BUGGY WHIP...  I consider it to be "ONE NEEDS TO TOTALLY UNDERSTAND LITHIUMS AND THE PITFALLS"

When one has a 15 year old component that has a limited life and they are failing....more than before...  THEN WHY would one use that to maintain an expensive bank of Lithiums.  If one is REALLY serious, then installing the proper Victron as well as the DC-DC charger is the proven and WORKS ....way to proceed.

Just some practical comments....from many sources and members.....

[Georgia Mike]

I had to purchase a new Magnum charger/inverter in 2022. At the time I wasn’t thinking about lithium charging capabilities, but I just went out and looked at my inverter and it looks like it can work with lithium. It says lithium compatible whatever that means. When I go to my Magnum remote, which is still the original one it only has lead acid, AGM and gel so I guess I have to upgrade the Magnum remote to get it to work with lithium if I want to convert.

 

[CAT Stephen]

@malcoll, 

 

Where are you at in your decision process? 

[malcoll]

My inverter/charger seems to work well, and I don't want to deal with big changes without much more research.  I ended up buying 8 6v batteries for $130 each, so I'll run these a few years and do my research over that time then make a change. Maybe Li batteries will continue to come down in price.

Great info everyone!

[JDPenn]

I think there is no better time than now to buy and invest in lithium and solar, and obtain the 30% tax credit, which is what I did. Also, get it now before the tariffs hit and increase prices across the board.

[CAT Stephen]

On 12/2/2024 at 9:43 PM, malcoll said:

My inverter/charger seems to work well, and I don't want to deal with big changes without much more research.  I ended up buying 8 6v batteries for $130 each, so I'll run these a few years and do my research over that time then make a change. Maybe Li batteries will continue to come down in price.

Great info everyone!

Thank You @malcoll,

The good news is now LiPO4 is 41% less expensive per watt-hour than Lead Acid deep cycle if you purchase a high quality / low cost LiPO4 brand such as AOLithium ($280 for 12V 200Ah).

In your case, assuming that you purchased GC2 220ah lead acid batteries, the usable capacity of you lead acid bank at 12V and 50% DoD (Depth of Discharge) is:

• 880ah * 50% = 440ah @12v (8 GC2 Lead  Acid in both series and parallel for 12V)

Watt*Hours for your Lead Acid bank is:

• 440Ah*12v = 5289 Watt*Hr

Cost Per Watt*Hr for your Lead Acid bank is:

• (8 Lead Acid * $130) / 5289 Watt*Hr
  • = $0.197 per Watt-Hr

 

For the AOLithium case @12V and 100% DoD (Depth of Discharge) is:

• 400ah @12v (Two 200Ah AOLithium LiPO4 in parallel)

Watt*Hours for the AOLithium LiPO4 bank is:

• 400Ah*12v = 4800 Watt*Hr

Cost Per Watt*Hr for the AOLithium LiPO4 bank is:

• (2 AOLithium * $280) / 4800 Watt*Hr
  • = $0.117 per Watt-Hr (41% cost reduction versus Lead Acid)

 

Then there is an additional 94% to 97% cost reduction in cycle life as a properly cared for LiPO4 bank can last 20+ years and ~5000 to ~8000 discharge cycles versus Lead Acid ~5 year lifespan with ~300 discharge cycles.  The mathematical differential is massive in terms of cost per cycle.  Also, Lead Acid watt hour claims are deceiving because discharge below 50% will destroy them, but you can discharge LiPO4 to 0% if you are willing to reduce cycle life to ~3000 discharge cycles.  Using 50% DoD for your Lead Acid bank versus 100% discharge for the AoLithium LiPO4 bank here is the cost per Watt*Hr discharge cycle:

• Lead Acid @DoD 50% - i.e. charge when capacity is 50%:
  • (8*$130) * 1000 / (5289 Watt*Hr * 3000 discharge cycles)  
    • = $0.72 per Kw-Hr cycle
• LiPO4 @DoD 100% - i.e. charge when capacity is 0%
  • (2*280) * 1000 / (4800 Watt*Hr * 3000 discharge cycles)  
    • = $0.04 per Kw-Hr cycle (94% cost reduction versus Lead Acid)
• LiPO4 @DoD 80% - i.e. charge when capacity is 20%
  • (2*280) * 1000 / (3840 Watt*Hr * 6500 discharge cycles)  
    • = $0.02 per Kw-Hr cycle (97% cost reduction versus Lead Acid)

Edited Wednesday at 03:52 PM by CAT Stephen

[CAT Stephen]

On 12/1/2024 at 6:29 PM, cbr046 said:

The better LiFePO batteries have overcharge protection, good protection, so if the inverter goes haywire and tries to zap the battery the BMS (battery management system) will shut down before damage occurs.  Will Prowse has demonstrated this numerous times through his video channel. 

That will be my strategy, anyway. 

- bob

Hello @cbr046,

 

Consider purchasing an all-in-one inverter/charger/solar controller from MPP Solar.  These units do not have the extreme long warranty of  the Victron Energy products, but are the best value for your dollar so that you can upgrade to LiPO4 the right way for only $485 with a 2.4Kw load capacity which will be sufficient for your RV:

• https://watts247.com/product/pip-lv2424-msd/

Or go all-the-way with their HYBRID unit for a few dollars more:

• https://watts247.com/product/hybrid-lv2424/

Since you follow Will Prowse (as I do also), his review of the MPP Solar products are EXCELLENT!!

[malcoll]

3 hours ago, CAT Stephen said:

Thank You @malcoll,

The good news is now LiPO4 is 41% less expensive per watt-hour than Lead Acid deep cycle if you purchase a high quality / low cost LiPO4 brand such as AOLithium ($280 for 12V 200Ah).

In your case, assuming that you purchased GC2 220ah lead acid batteries, the usable capacity of you lead acid bank at 12V and 50% DoD (Depth of Discharge) is:

• 880ah * 50% = 440ah @12v (8 GC2 Lead  Acid in both series and parallel for 12V)

Watt*Hours for your Lead Acid bank is:

• 440Ah*12v = 5289 Watt*Hr

Cost Per Watt*Hr for your Lead Acid bank is:

• (8 Lead Acid * $130) / 5289 Watt*Hr
  • = $0.197 per Watt-Hr

 

For the AOLithium case @12V and 100% DoD (Depth of Discharge) is:

• 400ah @12v (Two 200Ah AOLithium LiPO4 in parallel)

Watt*Hours for the AOLithium LiPO4 bank is:

• 400Ah*12v = 4800 Watt*Hr

Cost Per Watt*Hr for the AOLithium LiPO4 bank is:

• (2 AOLithium * $280) / 4800 Watt*Hr
  • = $0.117 per Watt-Hr (41% cost reduction versus Lead Acid)

 

Then there is an additional 94% to 97% cost reduction in cycle life as a properly cared for LiPO4 bank can last 20+ years and ~5000 to ~8000 discharge cycles versus Lead Acid ~5 year lifespan with ~300 discharge cycles.  The mathematical differential is massive in terms of cost per cycle.  Also, Lead Acid watt hour claims are deceiving because discharge below 50% will destroy them, but you can discharge LiPO4 to 0% if you are willing to reduce cycle life to ~3000 discharge cycles.  Using 50% DoD for your Lead Acid bank versus 100% discharge for the AoLithium LiPO4 bank here is the cost per Watt*Hr discharge cycle:

• Lead Acid @DoD 50% - i.e. charge when capacity is 50%:
  • (8*$130) * 1000 / (5289 Watt*Hr * 3000 discharge cycles)  
    • = $0.72 per Kw-Hr cycle
• LiPO4 @DoD 100% - i.e. charge when capacity is 0%
  • (2*280) * 1000 / (4800 Watt*Hr * 3000 discharge cycles)  
    • = $0.04 per Kw-Hr cycle (94% cost reduction versus Lead Acid)
• LiPO4 @DoD 80% - i.e. charge when capacity is 20%
  • (2*280) * 1000 / (3840 Watt*Hr * 6500 discharge cycles)  
    • = $0.02 per Kw-Hr cycle (97% cost reduction versus Lead Acid)

Hmmmm...wouldn't my useable ah be 880ah for (8) 220ah flooded batteries at 50% max DoD?  Then I would have to buy 4 Li batts.....to be close to same usable ah......so wouldn't the cost be about the same per Kw Hr??

[96 EVO]

18 minutes ago, malcoll said:

Hmmmm...wouldn't my useable ah be 880ah for (8) 220ah flooded batteries at 50% max DoD?  Then I would have to buy 4 Li batts.....to be close to same usable ah......so wouldn't the cost be about the same per Kw Hr??

Not if your FLA batteries are 6v!

2 of your batteries wired in series make 220AH at 12volts.

So run those 2 batteries to 50%, you have 110AH useable.

[malcoll]

10-4...good point!

[amphi_sc]

Wouldn't you also have to add in the retro fit costs of a new inverter/charger to get the right Lithium profile, and also the cost of isolation and charging from the alternator if you want to maintain that existing feature?

[wamcneil]

3 hours ago, amphi_sc said:

Wouldn't you also have to add in the retro fit costs of a new inverter/charger to get the right Lithium profile, and also the cost of isolation and charging from the alternator if you want to maintain that existing feature?

Wouldn't you also have to add in the retro fit costs of a new inverter/charger to get the right Lithium profile?

Maybe, maybe not. If the user is sufficiently educated on lithium chemistry and has a battery charger with custom settings that will allow for manual charge parameters compatible with lithium chemistry, and understand how to use the custom settings... maybe the old charger will work just fine. Oh, but they also need to sign and have notarized the official Monacoers Release of Liability and Lithium Battery Disclaimer fully acknowledging that they understand that ANY old charger that does NOT have a vendor approved and fully endorsed "lithium" charge profile, can and will ruin their batteries AND the charger/inverter is old and may/will fail catastrophically at any time. 🥲 Personally, I would recommend a newer inverter/charger, but I have a newer charger that DOES have a lithium profile and I don't use it. I didn't like the canned lithium profile and I'm using a custom profile anyway. There's no such thing as the one "right" lithium profile and there's nothing magic about a vendor-supplied set of preconfigured charger settings that has a text string like "lithium" or "lifepo4" associated with it.

and also the cost of isolation and charging from the alternator if you want to maintain that existing feature?

I would personally recommend isolating the systems. This can be as simple as disconnecting the battery isolators and connecting a small battery charger/maintainer to the chassis battery. Personally, I don't have the ability to charge the house battery from the alternator (other than manually engaging the boost relay) and don't miss it. 

Edited Thursday at 07:08 PM by wamcneil

[96 EVO]

I'm only luke warm to lithium batteries, even though I own plenty.

Recently, a nearby fire chief had one nearly burn his house down when it caught fire in a closet.

It was in a 'air-soft' gun ( whatever that is), wasn't being charged, wasn't being used, hadn't been modified.