Nimh Vs Li Ion Hybrid Batteries In Hybrid Vehicles

[AMAQ03]

This is a video to compare some of the advantages and disadvantages of the two most popular hybrid Battery technologies in hybrid vehicles today.

Kindly share your comments on real life experience using those hybrid batteries ( Nickel metal hydride vs Lithium Ion hybrid batteries )

Share your experience in terms of the following is prefered:
1. hybrid Battery capacity loss
2. Battery capacity drop effect on MPG
3. reconditioning success for NiMH
4. High Temperature effect on those batteries

[Cyker]

NiMH tech is actually still evolving quite a lot; There are a lot of different metal combinations that can be tuned for high power or longer life or even cost. There is also research into nano-structures for the anode and cathode which could potentially bring NiMH up to near Li+ levels of energy density.

One big breakthrough made in the last decade is low self-discharge NiMH tech; This allows them to hold 80% of their charge over a year (vs 0% ), but at the cost of some capacity.

The difference in weight for the cells isn't actually that different, but IIRC the weight penalty of NiMH is 20-30% more than Li+ for the same energy simply because you need more NiMH cells to get the same capacity as Li+

The life of the batteries is also not that different; NiMH used to have a shorter perceived life due to the memory effect, but if that's managed, both cell types can last a surprisingly long time. The killer is full charge and discharge - That will kill them pretty quickly, but as Toyota have demonstrated, keeping the cells between 80% and 20% can help extend their life considerably.

The cooling requirement is also very application dependent;Both cell types have similar optimal operating temperatures. However, NiMH cells have very low internal resistance and can supply loads of amps with less resistive heating. Li+ cells have much higher internal resistance and will probably explode if you try and pull the same number of amps because they have much higher resistive heating.

Under light load, both cell types can get away with similar cooling - It's under high load that things get dicey! This is also why Li+ need soooo many more cells in a Battery pack - The high internal resistance means you have to spread the amp draw over a lot more cells to get around the high internal resistance.

You could get away with air-cooling Li+ but you'd need so many cells in parallel to keep the resistive heating in check that it wouldn't be worth it.

There is still a lot of cool research going on with both types of batteries, not to mention new breakthroughs that use aluminium and sulphur.

I'm still hoping for something that can allow a small electric car to match my diesel Yaris for 600 miles range

[YarisHybrid2016]

I was under the impression that NiMH did NOT suffer the "memory effect" (only observed in satellites with early NiCd batteries that experienced more daylight than nighttime over YEARS).

A big problem with LiIon is thermal runaway, and a propensity to self-ignite. Some other Lithium Battery chemistries (most famously Lithium-Polymer) is extremely prone to catching fire, especially when charging, but also under high-current discharge where the cells can get hot (50+ deg. C).

When they can fix these issues, or find some way to substantially mitigate them, then Lithium-based Battery tech will be the way to go, until or unless an even higher energy-density Battery chemistry can be found.

As it is, there are calls for Lithium-based batteries of any description to be banned from air cargo. Whilst that is the case, is it wise to use these batteries in something as mega-expensive as a car? Sure, the odd rogue cellphone fire has destroyed a house, but cars are a lot bigger, a lot more expensive in their own right, and many people park them in garages that are integral to their property...

I'm watching what happens to the PiP as it uses Li-Ion battery tech. Hopefully there are no disasters, but it is an increased risk.

[Cyker]

NiMH doesn't suffer as badly as NiCd but it still is vulnerable to the 'memory effect' AFAIK. That said, there isn't just one 'type' of NiMH - It has lots of different chemistries, and I believe some are less prone than others. Supposedly the newer low self-discharge ones are less prone to it too.

I know what you mean tho', I've always been a bit leery of Li+ ever since one of my mate's RC planes spontaneously caught fire several minutes after being recovered from crashing into a tree!

The capacity advantages kinda trump everything else, tho', esp. for purely electric cars, and the problems can be engineered around. This is why e.g. the Battery pack of a Tesla is so over-engineered; It has an incredibly sophisticated cooling system and the pack itself is like tank armour

It's a little ironic that this negates a lot of the weight saving of the Li+ itself, but one big problem with electric cars is they won't be taken seriously except by enthusiasts until their range is at least on par with petrol cars, so the Battery tech is all about maximising energy storage above all else right now.

Personally I'd prefer to find alternative means of storing/generating the electricity. I quite like the idea of fuel cells, but hydrogen scares me and hydrogen cars have pretty disappointing range right now; Not much better than the best electrics. Plus making hydrogen currently wastes huge amounts of power which you could just stuff into a Battery.

I do wonder what happened to that solar collector that could turn air and CO2 into diesel/petrol (albeit slowly).

[MEP's Yaris GS]

Li-ion accepts charge better than Ni-MH, which is why side by side the PiP does better MPG than the standard Prius when both used as HV's.

[kithmo]

I was under the impression that NiMH did NOT suffer the "memory effect" (only observed in satellites with early NiCd batteries that experienced more daylight than nighttime over YEARS).

A big problem with LiIon is thermal runaway, and a propensity to self-ignite. Some other Lithium battery chemistries (most famously Lithium-Polymer) is extremely prone to catching fire, especially when charging, but also under high-current discharge where the cells can get hot (50+ deg. C).

When they can fix these issues, or find some way to substantially mitigate them, then Lithium-based battery tech will be the way to go, until or unless an even higher energy-density battery chemistry can be found.

As it is, there are calls for Lithium-based batteries of any description to be banned from air cargo. Whilst that is the case, is it wise to use these batteries in something as mega-expensive as a car? Sure, the odd rogue cellphone fire has destroyed a house, but cars are a lot bigger, a lot more expensive in their own right, and many people park them in garages that are integral to their property...

I'm watching what happens to the PiP as it uses Li-Ion battery tech. Hopefully there are no disasters, but it is an increased risk.

NiMH don't suffer the memory effect (the inability to charge above a certain threshold) but do discharge by themselves over time, Li-Ion less so.

IIRC the cellphone fires that have destroyed houses were the fault of the user mainly using an incorrect (cheap) charger and leaving the phone on charge all night unattended on a flammable surface (carpet), the charger overheating is what caused the fires.

Cars parked in garages overnight are no more likely to catch fire that your freezer is, as the charger supplied with the car has all the safety features built in.

You can't blame Li-Ion technology for the "issues" you mention, in most cases it was the users at fault.

[johalareewi]

There is also the possible patent problem with NiMH in vehicles.

https://en.wikipedia.org/wiki/Patent_encumbrance_of_large_automotive_NiMH_batteries

[Cyker]

Wow, I didn't know about that! They'll be kicking themselves for sitting on that and letting it stagnate

[AMAQ03]

I was under the impression that NiMH did NOT suffer the "memory effect" (only observed in satellites with early NiCd batteries that experienced more daylight than nighttime over YEARS).

A big problem with LiIon is thermal runaway, and a propensity to self-ignite. Some other Lithium battery chemistries (most famously Lithium-Polymer) is extremely prone to catching fire, especially when charging, but also under high-current discharge where the cells can get hot (50+ deg. C).

When they can fix these issues, or find some way to substantially mitigate them, then Lithium-based battery tech will be the way to go, until or unless an even higher energy-density battery chemistry can be found.

As it is, there are calls for Lithium-based batteries of any description to be banned from air cargo. Whilst that is the case, is it wise to use these batteries in something as mega-expensive as a car? Sure, the odd rogue cellphone fire has destroyed a house, but cars are a lot bigger, a lot more expensive in their own right, and many people park them in garages that are integral to their property...

I'm watching what happens to the PiP as it uses Li-Ion battery tech. Hopefully there are no disasters, but it is an increased risk.

Adding liquid thermal management systems can greatly improve Li Ion batteries and make sure they stay within allowable temps so they won't catch on fire or lose capacity from heating up, This is being used by the new ford focus electric which is very promising for future hybrid and electric vehicles using Li Ion technology with ford's type of liquid thermal management system.

[Paulscarbs]

Looked at table on video, couldn't spend long watching video talking about what I could already see - have a life to live. Video was very slow!

[AMAQ03]

Looked at table on video, couldn't spend long watching video talking about what I could already see - have a life to live. Video was very slow!

Thank you, its intended for lazy and interested people. more explanations in the video than the one world comparison in the chart.

I spend my spare time in life wisely.

[geo13647]

For some reason, most American gen 4 Prius seem to be fitted with Li-Ion technology. Apart from the Prius 2 eco, which has NiMh tech.

ALL the UK spec models seem to have NiMh batteries fitted according to the current comic, and contrary to the initial marketing blurb.

This would seem to suggest that mr T was having issues either getting sufficient Li-Ion batteries ( probably Tesla got them all),

Or, there is an issue wth them in terms of performance or reliability. Just curious, don't think we as end users will really notice much difference, but who knows! Thoughts?

Sent from my iPad using Toyota OC

[MEP's Yaris GS]

Cost is probably the main reason. And there is a big difference for end user, economy. The gen 3 plug-in with li-ion Battery demonstrates this, out performing any other gen 3 on a none plug in journey for MPG.

[kithmo]

19 hours ago, MEP's Yaris GS said:

Cost is probably the main reason. And there is a big difference for end user, economy. The gen 3 plug-in with li-ion battery demonstrates this, out performing any other gen 3 on a none plug in journey for MPG.

I think you're right there, I have the 7 seat Prius+ with a Li-Ion HV Battery, a heavier car but only 8 mpg less (real world) than the Gen 3 I used to have.