I'm happy to say that my MIMA is installed. I didn't take any pictures or mount the joysticks, as I had a bit of a time with severely sunburned feet and what feels like bronchitis coming on.
Anyway, it's working great so far. It sure is easy to drain that battery! I was able to get home with 90+MPG and much more battery power than I started with. Staying even, 100MPG should be much easier than it was before.
I'll surely have lots to say in the near future! Thanks Mike!
Does anyone have hard numbers on the efficiency of these NiMH batteries discharging and charging at very high rates? I was under the impression it was greater than 90%.
Does anyone have hard numbers on the efficiency of these NiMH batteries discharging and charging at very high rates? I was under the impression it was greater than 90%.
Has anyone investigated the feasibility of using a bank of super capacitors to act as primary storage during regen and also act as a buffer to slow the battery charging rate for optimum energy recovery and battery efficiency?
Does anyone have hard numbers on the efficiency of these NiMH batteries discharging and charging at very high rates? I was under the impression it was greater than 90%.
I would venture that the cells are greater probably than 90%, if not really close, in between the cars SOC range that avoids the top and bottom of the real battery state of charge. Getting close to the top and you start burning off power. If we had a way of accurately measuring heat dissipation we could determine wattage loss and develop a percentage.
I was thinking more along the lines of grid charging where we have some cells burning off a little current when they balance themselves when they are full which that, along with the efficiency of the Meanwells drops total efficiency down. I'm sure it's still cheaper in electrical costs than using more gas though.
Your driving habits are such that you don't typically park your Insight for long enough that differing self-discharge rates would cause significant cell imbalance. So how do you decide when to balance your battery?
I am very interested in using my balancer to extend the life of my battery. But other than using it after having parked my car for more than a week, I don't know when I should use it. I know that a battery deteriorates a tiny bit with each charge-discharge cycle, so it would seem that repeatedly overcharging a battery to balance its cells could reduce, not extend the battery's life.
Any clarification or suggestion would be appreciated.
As NiMh cells age their self-discharge characteristics deteriorate and they self-discharge more. This would be easy to deal with if all the cells in the pack 'wore out' at the same rate. They don't though so if you have cells that are worse than others and they self-discharge at higher rates, those cells will cause negative recals even if they otherwise have the same capacity as the rest. Granted the issue could also be aggravated by cells with worse capacity than the rest having the same issue of self-discharge as well but that is what is determined with cycling individual subpacks, which is a time consuming chore. There are multiple ways that a pack can be unbalanced, some of them appear as if they were the same type of failure when all cells are in series.
I looked into the supercap possibilities, a while ago.
The downside about capacitors is that the discharge curve is anything but flat, and to get as much energy storage as possible we would need to allow the caps to charge to substantially higher voltage than the battery pack to absorb as much regen as possible, and then use a buck regulator to actually charge the battery at an efficient rate from the caps. Simply putting the caps in parallel with the batteries will only help during the first few seconds of assist or regen, then the battery voltage will prevent the caps from raising in voltage to store more energy.
They are pretty expensive as well.
I ran into a guy at last months MIT swapmeet that will soon import 75V supercap banks that are used for electric busses in china, they charge up at each stop, and have sufficient range to make it to the next stop.I dont know how many packs ae in each buss, maybe that is a variable based on the distance between stops?
He did not have much information yet, and I suspect that we would be looking at thousands of $ for the packaged capacitor banks
I am curious as to how the grid charger discussion migrated to this MIMA thread?
Can you all move your posts or the relevant parts of them to the appropriate threads.
You may need to delete your posts here and then re-post them in the appropriate location. Use copy and paste to save your text.
I looked into the supercap possibilities, a while ago.
The downside about capacitors is that the discharge curve is anything but flat, and to get as much energy storage as possible we would need to allow the caps to charge to substantially higher voltage than the battery pack to absorb as much regen as possible, and then use a buck regulator to actually charge the battery at an efficient rate from the caps. Simply putting the caps in parallel with the batteries will only help during the first few seconds of assist or regen, then the battery voltage will prevent the caps from raising in voltage to store more energy..................
The Buck/Bost Conv.subsystem apparently does survive intact in many failed/junk Prius Hybrid Drives and the price should be very reasonable. This converter operates in both regen and assist in the Prius and the operating voltages are well beyond that of the Insight pack.
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