Ford won't build a battery production factory

Unless you plan to have the battery take up most of the floor pan area along with the weight involved, NiMh is a better option until capacitors improves in Wh capacity to size to act as an interface. You need a big capacity lithium battery to be able to push big watts into it without the use of pulse charging. Around 5CA is pretty much the limit for continuous charging, but 20CA is possible when pulse charging, but you would need the capacitors to store the regen and then pass it onto the traction battery in pulse form. The pwm of the pulse changes continuously as the state of charge increases because there is less and less available area in the anode material for the lithium ions to intercalate. High discharge rates are really only limited to the rate the ions can flow into and out of the electrolyte and recombine in the cathode, so high discharge rates do not also mean there can be high charging rates.
If the ions are released from the cathode while charging faster than they can intercalate into the anode or released into the electrolyte faster than they can recombine in the anode, they build up in the electrolyte resulting is serious heat generation, the killer of all types of lithium battery.

PS: Guessing you have a DIY plug in conversion. Did you post details for it here?
It is the ex Jason from Oz Prius and there is a very detailed thread here about all the mods he did before I bought it. 2006 iTech, let the mods / upgrading commence | PriusChat

T1 Terry

 

The Li-ion in Toyota hybrids is of smaller capacity, with fewer cells, than the NiMH pack. How does it match the regen performance of the NiMH?

 

As said many times, there a lot of flavours of Li-Ion.

 

Are you sure it is a smaller capacity? Toyota are offering either chemistry battery but fitting as OEM the lithium battery to the heavier high optioned market for weight saving to off set the weight of the additional options.
Both the NiMh and the lithium ion batteries have been re modelled so they fit under the rear seat rather than behind it, no real information seems to be available about the regen braking between the earlier model Prius and this latest generation so no idea if they have simply reduced the regen capability for the lithium ion battery or not. they do say they have tweaked the NiMh battery to accept faster charging so ?????
Who knows, maybe they have mastered the pulse charging from regen braking, it will be a brilliant step forward if they have. The lithium ion battery has fewer cells but a higher nom. voltage, 207v against 201v for the NiMh, that bit is interesting as well, 207v divided by 56 cells comes out to around 3.7v per cell. To get the same capacity from 56 cells as the NiMh 168 cells, wouldn't the individual cell capacity need to be greater?

T1 Terry

 

Yes it's true, Li-ion in 1.8 hybrid has 207 V and 3.6 Ah (~0.75 kWh), NiMh 201.6 V and 6.5 Ah (1.3 kWh).

The Li-ion is cycled between 20% and 90% SOC so roughly 520 Wh usable
The NiMh is cycled between 40% and 80% SOC so roughly 520 Wh usable

 

If you are comparing the two different battery chemistries my 2017 Trim Two is offended you forgot it has a NiMH battery. No need to compare regeneration across model generations. The closest to the Trim Two was the lighter Two Eco. Only 2MPG economy difference. Some of that was the higher recommended tire pressure.

 

And some of it because the lower weight of the Eco means more favorable parameters entered into the dynanometer for the test

The two different batteries have roughly the same usable capacity, but the NiMH needs a larger total capacity for long life.

 

I was referring to a comparison between the two newer build batteries, lithium ion V NiMh, for regen performance and cycle life.
Tesla would be at the top of the list when it comes to fast charging lithium ion cells, yet they have written into their BMS a method of counting how many fast charges the pack has been subject to and reducing the charge rate as the tally mounts, eventually down as far as the normal charge rate no matter what type of charging it is plugged into. Tesla says this is the prolong battery life, I'd put them forward as at the top of their game when it comes to battery building so if they have issues with fast charging lithium ion cells, how would Toyota be any different?
Time will tell I guess, 10 yrs plus working with LYP cells tells me that attempting to frequently fast charge lithium ion chemistry will lead to a whole world of wallet unless a method of pulse charging is involved.
Worth having a look through the model aircraft sites and check out the high rate discharge cells they have available, then look at the charging rate ....

T1 Terry

 

Also many air model batteries are flown/cycled fewer than 50x before replacement.

 

I guess the discharge rate won't be as fierce, but the recharge rate via regen will be the cell killer. If the lithium ion cell capacity is only 3.6Ah, 130 amp regen, which isn't as high as my Gen 2 can develop, would be a 36CA charge rate These are lithium ion cells, not super capacitors .... or are they sort of a hybrid of the two? Ultra thin material coating on very large conductor plates, might be a market for the graphene anodes there has been so much hype and spin about if they can actually get the material itself to be the lithium ion intercalating material rather than the much used graphite in the current generation of lithium cells

T1 Terry

 

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