[EV_Jibareaux]

Greetings,
My home is powered by LiFePo4, my bike is LiPo, I built both battery packs and the corresponding BMS.

I've begun the design phase of my '89 Volvo 245 manual wagon and I've come across an interesting option in battery weight/safety. I am aware of the lower Watt:Weight ratio of the LiFePo4, my interest is in the stability of the chemistry.

The vehicle I'm building needs to have at least a 70km range and will be used primarily for early morning school attendance commute. I am heralding back to my days of race car building by lightening the car, fabricating a sub-frame and cross-member bracing to manage the additional torque as well as replacing the suspension with air bags and lighter springs.

the question: has anyone else built a LiFePo EV?
Who is a good wholesale supplier for L4?

 

[brian_]

the question: has anyone else built a LiFePo EV?
Who is a good wholesale supplier for L4?

What do these mean?
"LiFePo" doesn't mean anything.... presumably you meant LiFePO4 chemistry, not something like Li-Po (lithium-ion cells with polymer electrolyte) construction.
"L4" doesn't mean anything to me.... did you mean LiFePO4 chemistry? If you want a shorter term for that, try "LFP". Or is it a brand name or something?


The popular cell type for DIY conversions for a few years, between the lead-acid era and the current mostly salvaged EV battery era, was LiFePO4 prismatic cells (usually CALB cells in plastic cases); lots were done, lots are still in use. It appears that they're rarely used now due to cost and performance.

I assume you didn't mean to ask about lithium-polymer use, but some Hyundai or Kia EVs have lithium-polymer batteries, but of course they are not using hobby cells.

 

[remy_martian]

There are some LiFePO builds on here - just search the site.

I don't understand the "stability of the chemistry" concern, though. We've moved on from such girlyman worries 😉

You talk about your experience in lightening a vehicle, then you dump a bunch of unnecessary mass into the car that all your experience and technique negates. The scale of an EV pack makes battery conditioning a minimal overhead.

Unless you're driving a nailgun into your pack or using charging methods, or running temperatures, outside the manufacturer limits, what's the big deal?

 

[EV_Jibareaux]

What do these mean?
"LiFePo" doesn't mean anything.... presumably you meant LiFePO4 chemistry, not something like Li-Po (lithium-ion cells with polymer electrolyte) construction.
"L4" doesn't mean anything to me....

You recognize the chemistry I'm referring to, I suspect you're being intentionally obtuse for gatekeeping purposes. Perhaps adding the correct chemistry abbreviations will assist other users of this forum in the future.

Are you familiar with the Canadian transit buses that run A123 lifepo4 cells (eg: Lifepo4 A123 cells tested | eBay)

have you built a road vehicle with a LiFePO4 chemistry battery bank?
have you built a road vehicle with a LIPO (eg: 18650 type cell popular in most everything from laptops to EV)?

what was your performance experience with the different types of chemistry?

 

[brian_]

You recognize the chemistry I'm referring to, I suspect you're being intentionally obtuse for gatekeeping purposes. Perhaps adding the correct chemistry abbreviations will assist other users of this forum in the future.

If by "gatekeeping" you mean reducing the amount of meaningless babble in the forum, then yes. But since your title is "LIPO vs LiFePO4 in a vehicle?", it's certainly not clear what you're asking. Maybe you just decided to ask only about LiFePO4 after typing the title and forgetting what you put there?

Are you familiar with the Canadian transit buses that run A123 lifepo4 cells (eg: Lifepo4 A123 cells tested | eBay)

There are LiFePO4 batteries in some production vehicles, particularly buses and particularly from manufacturers who went with A123 before the company collapsed. Even the Chevrolet Spark EV had A123 LiFePO4 modules... for about a year until A123 crashed and GM switched to LG Chem modules with NMC pouch cells. The two batteries used the same pack enclosure, but there were enough detail changes in the car that a good comparison between the batteries is not possible just by comparing the 2014 and 2015 production vehicle performance.

have you built a road vehicle with a LiFePO4 chemistry battery bank?
have you built a road vehicle with a LIPO...

what was your performance experience with the different types of chemistry?

Nope. Almost no one has built EVs with multiple lithium-ion chemistries, and the other differences in the cells are probably more significant than the electrode chemistry.
And LiFePO4 vs Li-Po is not a chemistry difference; you can buy LiFePO4 Li-Po cells, non-LiFePO4 Li-Po cells, LiFePO4 non-polymer cells, and non-LiFePO4 non-polymer cells... that's every combination, because electrode chemistry and electrolyte type are not related.

have you built a road vehicle with a LIPO (eg: 18650 type cell popular in most everything from laptops to EV)?

And back to clarity...
The 18650 format (18 mm diameter by 65.0 mm long cylinder) does not imply any particular electrode chemistry (e.g. LFP, NMC, NCA, LTO...) and so there's a wide range in performance between cells of this format; most are not LFP (LiFePO4).
Cells in this format are typically not polymer electrolyte (which is what "Li-Po" means), so "LIPO" and "18650 type cell" are not related concepts at all.
What you can salvage from a laptop or buy for a vaping device is not interchangeable with what goes in a Tesla battery module; the generic made-in-China 1200 mAh 3.7 V 18650 cell in the flashlight beside me is not at all comparable to the cells in any Tesla battery.

 

[EV_Jibareaux]

Have you ever built an EV with any type of lithium based cell?

if yes, what type?

 

[cricketo]

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[john61ct]

Tesla is increasing its use of LFP in recent years.

Energy density is a bit lower, power is fine, longevity is 10x number of cycles all else being equal, so cost per year MUCH cheaper.

And nearly zero fire risk compared to all the usual 3.6-3.7V nominal chemistries.

 

[philsev]

Greetings,
My home is powered by LiFePo4, my bike is LiPo, I built both battery packs and the corresponding BMS.

I've begun the design phase of my '89 Volvo 245 manual wagon and I've come across an interesting option in battery weight/safety. I am aware of the lower Watt:Weight ratio of the LiFePo4, my interest is in the stability of the chemistry.

The vehicle I'm building needs to have at least a 70km range and will be used primarily for early morning school attendance commute. I am heralding back to my days of race car building by lightening the car, fabricating a sub-frame and cross-member bracing to manage the additional torque as well as replacing the suspension with air bags and lighter springs.

the question: has anyone else built a LiFePo EV?
Who is a good wholesale supplier for L4?

I have used iron phosphate batteries for over ten years in my conversions. Never one problem. I do not use a BMS. I would definately use a bms with any other chemistry. That chemistry is the best in my opinion for safe and stable. I do not care to hear from anybody about me not using a BMS. It has worked great for me and everyone I have talked to.
Phil

 

[john61ct]

Yes the "need" for Battery Murdering Systems is overblown, but then should be recommended for noobs not willing to do the research required to go without.

Really just a collection of functionalities, and there are dozens of ways to skin each cat.

 

[philsev]

Yes the "need" for Battery Murdering Systems is overblown, but then should be recommended for noobs not willing to do the research required to go without.

Really just a collection of functionalities, and there are dozens of ways to skin each cat.

well said and right on!
phil

 

[cricketo]

I knew one police guy who said something like this: who has the most shooting "accidents" on the police force ? The SWAT!

Point being, some folks may be experienced enough to take the shortcuts here and there, but eventually their arrogance will bite them in the ass. Don't make a habit of taking shortcuts, design systems properly like a reputable commercial vendor would do.

 

[remy_martian]

I have used iron phosphate batteries for over ten years in my conversions. Never one problem. I do not use a BMS. I would definately use a bms with any other chemistry. That chemistry is the best in my opinion for safe and stable. I do not care to hear from anybody about me not using a BMS. It has worked great for me and everyone I have talked to.
Phil

Every chemistry is safe if you charge the cells like a grandmother.

 

[john61ct]

No a lot more knowledge, equipment and care protocols are required to make the higher density 3.6-3.7V nominal chemistries acceptably safe.

I would very strongly advise against using any such for a mobile living scenario.

LTO and LFP only.

Every chemistry is safe if you charge the cells like a grandmother.

 

[remy_martian]

Thanks, grandma...you made my point 😂

 

[OR-Carl]

It is true that LFP will not catch fire if you overcharge them to the point of ruining them. It is also true that burning down your house as well as your poorly designed battery would add insult to injury. But to call a BMS a battery murdering system borders on laughable. Every electronic device that runs on a lithium battery has a BMS. Most of them are probably not using LFP cells either.

Yes, you can do all the things a BMS does, but unlike the BMS, you can FORGET TO DO THEM. I think it is cheap insurance. If you can afford to replace the battery bank, why would you cheap out on a BMS?

 

[john61ct]

No one is talking about saving money.

Most BMSs are just horribly unreliable, and often actually cause their bank's failure or accelerate the EoL. Bad design, horrible build quality, counterfeit components...

As stated, their functionalities can be achieved in many alternative ways, and that is specifically for the goals of reliable safety and better system integration.

A single device to try to do it all at a cheap price point is not ideal.

And over reliance on full automation is stupid. The owner does need to understand and closely monitor what's going on regardless, both for safety but also to get the long lifespan required to get decent value out of the large investment.

 

[remy_martian]

True, but not everybody's an engineer, not everybody can look at this stuff without their eyes getting glazed over, most people are "set and forget", many people these days are broke and getting broker, and I can't even get my daughter to check the oil in her car once a month

 

[cricketo]

Most BMSs are just horribly unreliable

Why would you call out junk unsupported BMSes from China (I assume that is what you're referring to), but say not junk noname motors, motor controllers and battery cells ? Or do you actually not use other junk components, with BMS getting a special treatment ?

 

[EV_Jibareaux]

I'm definitely going with LifePo4 due to the cost-benefit with longevity. My goal is to be able to drive to the capitol city and back, that's a range of 140km (round trip) with 600m altitude change, half is down hill. I've not done the math to determine how many amp hours I'll need for that journey but I'm stripping that car of any extra weight.

I pulled nearly 500 kg's out of the front and the coil over struts have topped out. I'm considering airbag suspension. I know the weight of the motor and can determine the weight of the coolant, I've got a lot of space under the hood and a 60 liter fuel tank that still needs to be removed. I'll be placing batteries spread through the vehicle.

slightly off topic: holy merde the trolls on this forum are obnoxious, the top 3 monthly posters have already been silenced in my feed as they bring nothing of value to any conversation.