Supercapacitors in a UK Honda Insight MK1 Hybrid.
Discussion
I'm not aware of any other supercapacitor equipped road going vehicles in the UK apart from mine.
The ageing old Nimh technology hybrid battery pack has been replaced with a state of the art Lithium Supercapacitor pack made up of 50 x 2200F Capacitors. They are low internal resistance, very efficient >95%, and effectively have an unlimited cycle life.
In my MK1 Honda Insight with tweaked electronics to manage them, it's a significant improvement in instant power over the old pack. They only store about 0.8ah but that's enough for rapid acceleration/braking with high efficiency.
Tech details and photos etc are on this thread over at www.insightcentral.net
http://www.insightcentral.net/forums/modifications...
http://www.jmenergy.co.jp/en/products_cell_rami.ht...
https://en.wikipedia.org/wiki/Lithium-ion_capacito...
https://en.wikipedia.org/wiki/Supercapacitor
Might think about adding them to the MK1 Insight UK rally car.
http://www.oaktec.net/phdi/p1.nsf/supppages/oaktec...
The ageing old Nimh technology hybrid battery pack has been replaced with a state of the art Lithium Supercapacitor pack made up of 50 x 2200F Capacitors. They are low internal resistance, very efficient >95%, and effectively have an unlimited cycle life.
In my MK1 Honda Insight with tweaked electronics to manage them, it's a significant improvement in instant power over the old pack. They only store about 0.8ah but that's enough for rapid acceleration/braking with high efficiency.
Tech details and photos etc are on this thread over at www.insightcentral.net
http://www.insightcentral.net/forums/modifications...
http://www.jmenergy.co.jp/en/products_cell_rami.ht...
https://en.wikipedia.org/wiki/Lithium-ion_capacito...
https://en.wikipedia.org/wiki/Supercapacitor
Might think about adding them to the MK1 Insight UK rally car.
http://www.oaktec.net/phdi/p1.nsf/supppages/oaktec...
Max_Torque said:
Are the Caps driven through a DC:DC convertor to be able to access most of the energy stored in them?
No it doesnt need it. The operating voltage window for the cap bank is 110-190v (0-100%) and the Insight system with a few tweaks can use all that available window. So I am accessing all the available power in them.
Note these are Lithium Supercapacitors. They are like a hybrid cross of a traditional capacitor and a Lithium battery.
This link explains best. https://en.wikipedia.org/wiki/Lithium-ion_capacito...
Edited by peterperkins on Sunday 7th May 09:02
It's not all about ROI as I'm sure you appreciate. Especially when developing systems and experimenting.
It's also about interest, education, furthering knowledge, tackling and solving problems etc all things i enjoy.
Lets look at ROI though.
The 2200F caps I used are not available now they have been replaced with 3300F prismatics.
(50% greater capacity)
The new caps cost approx 100Euros each.
So 50 = 5000 Euros.
Let's assume my 50 x 2200F cost about 3500EU for comparisons.
The capacitor management system cost was negligible <50EU
The mods required to the Insight systems are fairly simple and negligible in cost.
Installation etc is all bespoke but just takes time and care.. It's not finished this is a test vehicle and developing project.
A new Honda IMA battery is 2555EU with one year warranty.
Lifetime let's say 10-15 years.. (Thats how long most have lasted in service)
Yes it has more capacity, but the idea with the supercaps is not to replace the battery with an equivalent capacity in F
It's to improve the efficiency of the IMA system. The Insight gets most of it's fuel efficiency from the highly developed lean burn engine. The IMA is mainly used to accelerate/decelerate etc. Supercaps make that process much more efficient.
You can see the total cost of these supercaps with effectively unlimited cycle life is not as prohibitive as you were perhaps thinking.
Calendar life we don't know yet but I would expect them to last at least as long as the Nimh packs in service.
For savvy owners wanting better IMA performance in average terrain the supercap pack looks quite attractive if you look beyond the initial outlay. Like a lot of members on here some Insight owners are also prepared to pay a premium for better performance or cutting edge tech. It will be interesting to see how things develop.
It's also about interest, education, furthering knowledge, tackling and solving problems etc all things i enjoy.
Lets look at ROI though.
The 2200F caps I used are not available now they have been replaced with 3300F prismatics.
(50% greater capacity)
The new caps cost approx 100Euros each.
So 50 = 5000 Euros.
Let's assume my 50 x 2200F cost about 3500EU for comparisons.
The capacitor management system cost was negligible <50EU
The mods required to the Insight systems are fairly simple and negligible in cost.
Installation etc is all bespoke but just takes time and care.. It's not finished this is a test vehicle and developing project.
A new Honda IMA battery is 2555EU with one year warranty.
Lifetime let's say 10-15 years.. (Thats how long most have lasted in service)
Yes it has more capacity, but the idea with the supercaps is not to replace the battery with an equivalent capacity in F
It's to improve the efficiency of the IMA system. The Insight gets most of it's fuel efficiency from the highly developed lean burn engine. The IMA is mainly used to accelerate/decelerate etc. Supercaps make that process much more efficient.
You can see the total cost of these supercaps with effectively unlimited cycle life is not as prohibitive as you were perhaps thinking.
Calendar life we don't know yet but I would expect them to last at least as long as the Nimh packs in service.
For savvy owners wanting better IMA performance in average terrain the supercap pack looks quite attractive if you look beyond the initial outlay. Like a lot of members on here some Insight owners are also prepared to pay a premium for better performance or cutting edge tech. It will be interesting to see how things develop.
Edited by peterperkins on Sunday 7th May 13:33
peterperkins said:
It's not all about ROI as I'm sure you appreciate.
Indeed, but it probably tells us why this is not a more common conversion (but will probably get more common as the original batteries age and need to be replaced by something!peterperkins said:
the idea with the supercaps is not to replace the battery with an equivalent capacity in F
It's to improve the efficiency of the IMA system. The Insight gets most of it's fuel efficiency from the highly developed lean burn engine. The IMA is mainly used to accelerate/decelerate etc. Supercaps make that process much more efficient.
How do they increase efficiency? I suspect that they may manage to widen the SOA for the system, by allowing a higher power transfer, that necessarily comes with an increased absolute loss (because P = I2R!)It's to improve the efficiency of the IMA system. The Insight gets most of it's fuel efficiency from the highly developed lean burn engine. The IMA is mainly used to accelerate/decelerate etc. Supercaps make that process much more efficient.
Then you get into the issue of the primary inverter efficiency, which WILL be working with a greater voltage differential and so will have reduced efficiency.
In the real world, these caps might allow you to maintain an electric boost across a broader range of driving conditions, but ABSOLUTE economy is about driving at a single, very load load operating point, which the original system was perfectly capable of.....
I should say, i'm certainly not against mods like these, as it's interesting to see different approaches to problems ;-)
The insight inverter is designed for a voltage window of about 120-190V so the supercaps window fits pretty well into that.
In a stock IMA system the Nimh nominal 144V pack voltage will swing from around 120v to 185v+ depending on load/conditions/soc.
Efficiency increases come from reduced internal resistance in the supercap pack.
The IR of the supercaps pack (50 cells) is approx 50milliohms (excluding connections) compared to about 400 for a brand new Nimh pack and over 600 for one several years old.
There is a correspondingly less significant drop/change in voltage under load/charge and less energy wasted due to internal heating.
The supercaps also have a low self discharge rate in the order of <5% after 3 months. The stock Nimh especially once a few years old has a very high SD, and could be essentially flat after just a month or so. On a daily basis the stock system has to replenish capacity lost to SD whereas the supercaps basically don't. It all adds up to an increase in IMA efficiency.
The variations in the SD rate of cells in the Nimh packs also gives rise to significant balance issues in standard cars which the system has difficulty correcting.
In testing so far I cannot detect any significant (+/-10mv) difference in supercap voltage after journeys, trips, they are extremely tightly balanced.
Absolute economy in the Insight mainly comes from the highly developed lean burn engine.
The IMA plays a small part in city driving stop/start/assist/regen and with mild hills etc but as the Nimh packs age they can become a burden on the car.
Owners with flat terrain in the US on long journeys can get higher mpg without IMA in an Insight than with it.
In a stock IMA system the Nimh nominal 144V pack voltage will swing from around 120v to 185v+ depending on load/conditions/soc.
Efficiency increases come from reduced internal resistance in the supercap pack.
The IR of the supercaps pack (50 cells) is approx 50milliohms (excluding connections) compared to about 400 for a brand new Nimh pack and over 600 for one several years old.
There is a correspondingly less significant drop/change in voltage under load/charge and less energy wasted due to internal heating.
The supercaps also have a low self discharge rate in the order of <5% after 3 months. The stock Nimh especially once a few years old has a very high SD, and could be essentially flat after just a month or so. On a daily basis the stock system has to replenish capacity lost to SD whereas the supercaps basically don't. It all adds up to an increase in IMA efficiency.
The variations in the SD rate of cells in the Nimh packs also gives rise to significant balance issues in standard cars which the system has difficulty correcting.
In testing so far I cannot detect any significant (+/-10mv) difference in supercap voltage after journeys, trips, they are extremely tightly balanced.
Absolute economy in the Insight mainly comes from the highly developed lean burn engine.
The IMA plays a small part in city driving stop/start/assist/regen and with mild hills etc but as the Nimh packs age they can become a burden on the car.
Owners with flat terrain in the US on long journeys can get higher mpg without IMA in an Insight than with it.
Edited by peterperkins on Monday 8th May 06:50
Edited by peterperkins on Monday 8th May 07:36
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