Will LiFePO4 save me from having to charge in ammo cans?

axca

1 mW
Joined
Aug 10, 2018
Messages
14
Location
Kanata, ON
Greetings. My BBS02 36V 500W has been on the frame for a few weeks now while the rest of the bike is being assembled by my trusty LBS. Surely by the time of the first snowfall, my little do-it-by-lbs project would be complete :!:

I am fond of dilly-dallying but the weather here sure doesn't. Then there is this recommendation about "charging the battery outside if at all possible" ... :shock: In a place where there are mainly 2 seasons with a beautiful fall but far too short, I can only sigh.

Anyhow ... onto battery, which I thought would be fairly straightforward ... until I came across this thread (very glad Dan and your loved ones were relatively unscathed, save for the PTSD and lost belongings - and I salute your willingness and candor in sharing your story here - it definitely jolted me upright reading the entire thing).

Obviously nothing is risk-free. The simple act of biking down main street here in any Canadian city risks life and limb far more than charging a slab of NCA battery ... but I don't plan on using the bike as a means of transportation (and not possible for half the year anyway - if gas hits $3/L then electric snowmobile or a Nissan Leaf would be more practical).

I am just hoping to minimize avoidable risks. Moreover, should such a calamitous moment ever arrive as when boss lady sees thick smoke and flashes of pyrotechnics spewing out of a battery, a different kind of fire could engulf the house with me in it.

From the above thread Dan spoke favourably of Ping batteries from past experience.

Here is also a quote from the thread just below:

www.recumbents.com said:
...
My Ping battery is over 9 years old and it's still working fine. It was used heavily for 5 years, sat around for 4 years (I charged it every 6 months or so), and is now being used again.

Warren

A 36V 10AH Ping LFP battery (in its 11.4" x 5.7" x 1.9" incarnation likely will fit into a standard triangle bag I reckon) weighs 3.4 kg while a 36V 14AH best of the reputable NCA 18650 framepack weighs just 1 lb more. And 36V 17AH just 2 lbs more.

I understand that most folks around here would hands down pick the NCA 18650 packs with their 50% higher range at roughly the same weight. But for recreational use, is there any downside to LiFePO4? I also know that there have been users here attesting to incidents of LFP catching fire. But I am looking for "safer" as defined by this Battery University write-up.

Lastly, a possible side benefit (to me anyway) to having something like an LFP pack in a frame bag could be a built-in "suspension effect" that cushions vibration and decreases rattle from rigid framepacks clattering on sliders - especially offroad. But does LFP "soft pack" (such as the Ping) in a frame bag need extra padding?

In the end it is probably a decision with no "right or wrong" answers but heavily down to preference / personal threshold and degree of "risk-averse-ness". But I would appreciate any perspectives.

Thanks.
 
Any battery capable of running a bike has the potential to start a fire, but LiFePO4 is much less likely than any Li-ion chemistry. I can only remember a few LiFePO4 fires and none of them were "spontaneous".

Li-ion chemistry can be pretty safe if used properly. Think about how many laptop computers and cell phones are out there. Fires mostly happen when cells are abused in some manner.

The Ping "duct tape" packs are prismatic pouch cells, so pretty easy to damage in the event of a bike crash or tip-over. If using any kind of pouch cells, a hard sided case is really a good idea and a way to compress the cells is recommended.

I've used both kinds. If you don't need a lot of range and weight is not an issue, then LiFePO4 might be a good choice. Personally, I would not go back to those since I'm spoiled with the higher energy density of Li-ion.
 
fechter said:
...
The Ping "duct tape" packs are prismatic pouch cells, so pretty easy to damage in the event of a bike crash or tip-over. If using any kind of pouch cells, a hard sided case is really a good idea and a way to compress the cells is recommended.

Good to know! With the 1.9"/50mm "slab" version I am hoping to be able to slide something rigid into the sides of a frame bag to brace any hard hits. I personally don't mind duct tape or the likes acting as soft cushion to dampen vibration. It seems that vibration and Canadian winter are all detrimental to Li-ion health.

If I do go the Ping LFP-battery-in-framebag route, I shall ask the vendor as to why they don't just provide some means of added compression at a modest cost, which some customers would gladly bear (as an option).


fechter said:
I've used both kinds. If you don't need a lot of range and weight is not an issue, then LiFePO4 might be a good choice. Personally, I would not go back to those since I'm spoiled with the higher energy density of Li-ion.

Indeed for my purposes it might be more of a "peace-of-mind" placebo effect. But I work in a field where placebo effect has it place.

Do I still need one of those for charging an LFP pack in? :wink:

Anyhow, how about the Grin Satiator? I am sure everyone could agree that its single outstanding "con" is cost. But nothing else reputable on the market charges a battery < 84V to a certain percentage or other specs as reliably as this, is there? There is no reason why the safety aspects of charging a 36V LiFePO4 pack couldn't be improved by the Satiator, correct?

Thanks.
 
18650's dont burn down houses unless you really be a dick to them.
pouches is a no-no in my book, and workshop.

use 18650 cells from a reputable brand and source and dont charge harder then you have to. if you have 8 hours to charge then set the charge rate to take 8 hours.

i usually advise that the money you save on using cheap ass batteries should be put into paying a better fire insurance on the house.
 
I've never heard of a LiFePo4 pack going up in thermal runaway. It's a big battery, so obviously the potential for it to start a fire is always there, if it shorts out, etc then things will get really hot. Some of those things can catch fire.

But that whole self feeding fireball thing, I don't think so. They don't gas off anything flammable.

I charge my A123 LiFePo4 pack inside in the winter, take it inside places I visit, on the bus, etc. I would be leary of doing those things with an 18650 pack, and no way in heck with an RC LiPo pack.
 
flippy said:
18650's dont burn down houses unless you really be a dick to them.
pouches is a no-no in my book, and workshop.

What you say about "not being a dick" to the battery is no doubt true in a rhetorical sense. Problem is that the very act of throwing a slab of battery on a mountain bike is to invite some degree of "dicking around" during which impact and vibration are par for the course ...

I kinda understand the downsides to pouches, as they need some room to expand - but just a bit ... and not to let it swell too much. And they can't take hard hits. But reality is exactly that - Tesla batteries can't even take hard hits.

So what about Yamaha, Bosche, Haibike and the rest of the commercial ebike honchos? For one thing there is no evidence they are using "modern" NCA-based "Tesla cells" (in a manner of "lay speak"). If there is I'd very much like to see if you (or anyone else) have on hand - if only to satisfy my own curiosity and "peace of mind". There is indirect evidence that many use less "exuberant", but modestly safer NCM (or NMC) cells ... at least I did read somewhere that BionX batteries are/were NMC-based. But that's a digression.

And we really don't know how "finicky" commercial Brand-named packs are since it's like with Mercedes or Audi - only the ones paying for repair know how hard they get hit (on both battery and wallet). For all I know, the OEM batteries could be "shut-down" for the slightest jolt in the circuitry, and then it's a trip to the dealer. The truth is that if my laptop did that, I would hardly use one.

But hey, this is not to say there wouldn't be an OEM eMTB with my name on it some day. For starters it is often more cost-effective in the initial outlay (as compared to assembling one from scratch).


flippy said:
use 18650 cells from a reputable brand and source and dont charge harder then you have to. if you have 8 hours to charge then set the charge rate to take 8 hours.
That's certainly sound advice. As much as a healthy respect for Li chemistry and a need to exercise due diligence are called for, I just wouldn't want the whole act of charging a battery to become a rigmarole unto itself ... as in putting it in an ammo box with a garbage can over top ... anyway, I am not sure if anyone actually does that. But then again, it's clear that converted ammo boxes are sold and used for this very purpose.


flippy said:
i usually advise that the money you save on using cheap ass batteries should be put into paying a better fire insurance on the house.
Last I checked, the reputable sellers of sub-10 lb 10-14AH 36V packs all sell in the 350 to 400 USD/Euro range. So price difference is minimal. I was just looking for the safest (and readily accessible) chemistry within the Li family. And I am perfectly willing to accept some trade-off in capacity.

But a Grin Satiator is still not a bad idea, eh/uh?
 
All I can add is that lifepo4 is not any safer then li-ion. They will catch on fire.

I had one of the 26650 a123 cells catch on fire while I was removing it from a battery pack. It was my fault I shorted out the cell which punched a hole on the side of the can. I heard the pressure escaping then saw the fire, like a blowtorch, it would make a tesla cell proud. It was very violent. I was able to eventually put out the fire by pouring water on it, but it kept reflashing until the pressure died down. I wouldnt want to be around when a whole battery pack full of lifepo4 catches on fire, it would be as bad as any li-ion fire.

I never had the one of the more "dangerous" li-ion cell catch on fire, and I have used hundreds of those, I started to use lifepo4 because I kept hearing they were safer, but after my experience I treat them the same as li-ion. I think the best advice is don't abuse the battery, and build your pack to survive a crash without getting punctured.

I have over 200 of these cells and still plan on using them on building a battery pack, these a123 cells are just too powerful not to use them. As long as they don't get punctured they are very safe. On a batterypack that never gets moved around or bang around its perfect for them. The only disadvantage over li-ion is size/weight, nothing beats li-ion in that area.

I never charge any of my batterypacks in ammo cans, but rely on alarms or a balance charger to get me a safe charge. I monitor the balancing everytime. That is the number one thing you can do to keep your battery safe is monitor the balancing. You can't rely on the BMS to save your pack from worst case scenario. Never had any situations of a lithium battery getting overcharged, I monitor for that everytime.


bae cell fire.jpg
 
axca said:
What you say about "not being a dick" to the battery is no doubt true in a rhetorical sense. Problem is that the very act of throwing a slab of battery on a mountain bike is to invite some degree of "dicking around" during which impact and vibration are par for the course ...

i mean that you dont charge them on the limits of what they can take or generally treat them poorly.

axca said:
I kinda understand the downsides to pouches, as they need some room to expand - but just a bit ... and not to let it swell too much. And they can't take hard hits. But reality is exactly that - Tesla batteries can't even take hard hits.

you can smash a tesla into a concrete wall at 100mph with only a few light fires where some cells are busted. a lot less spectaculair then pouch based packs that generally are a lot more "dramatic" when they are punctured as there is several orders of magnitude of more energy stored in a pouch compared to a singel cells that holds 12Wh at best. so you only get a slight wiff until the lithium neutralizing goop they cover the entire battery in smothers the fire.

axca said:
So what about Yamaha, Bosche, Haibike and the rest of the commercial ebike honchos? For one thing there is no evidence they are using "modern" NCA-based "Tesla cells" (in a manner of "lay speak"). If there is I'd very much like to see if you (or anyone else) have on hand - if only to satisfy my own curiosity and "peace of mind". There is indirect evidence that many use less "exuberant", but modestly safer NCM (or NMC) cells ... at least I did read somewhere that BionX batteries are/were NMC-based. But that's a digression.

dont focus on chemestry. that is of no relevance in this. this is a case of simple battery quality, construction and control with a BMS. that is what matters and all of those have to fail before something dramatic happens with a battery.
pouch based packs usually have much stronger armour around the pack to protect it because of the fact that when a single pouch goes the rest will go with it. with 18650's that risk is extremely small.

flippy said:
That's certainly sound advice. As much as a healthy respect for Li chemistry and a need to exercise due diligence are called for, I just wouldn't want the whole act of charging a battery to become a rigmarole unto itself ... as in putting it in an ammo box with a garbage can over top ... anyway, I am not sure if anyone actually does that. But then again, it's clear that converted ammo boxes are sold and used for this very purpose.

why would you use ammo boxes if you done everything right? proper cells, decent build quality with cell holders, spot welded with real nickel and a decent bms and name brand charger means the risk of something happening is basicaly zero.



flippy said:
Last I checked, the reputable sellers of sub-10 lb 10-14AH 36V packs all sell in the 350 to 400 USD/Euro range. So price difference is minimal. I was just looking for the safest (and readily accessible) chemistry within the Li family. And I am perfectly willing to accept some trade-off in capacity.

But a Grin Satiator is still not a bad idea, eh/uh?

again: dont look at chemestry. look at actual specs and make sure you have a battery that EXEEDS by a decent margin what you need. you would not use a car that can drive from and to work with 1 mile of range to spare on a single trip.

buy the best and biggest battery one can afford and cut the capacity by only charging to 4.05v to maximize lifespan so you can enjoy your setup for years.
 
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