Well I ordered the batteries for the Porsche. I’m upgrading from the Lead Acid pack that I currently have to a Lithium Ion pack. I have been using a set of 20 6vdc lead acid batteries for a total of 120vdc. I am replacing the pack with a set of 42 3.45vdc batteries for a total of 145vdc. The higher voltage will give me a bit more power and reduce the current at a given speed when going down the road. This should make the car slightly more efficient, though hardly noticeable. What will be noticeable is the improved power. These batteries will have very little peukert effect. Peukert effect is the drop in voltage that a battery has when under load. The internal resistance of the battery will cause a drop in voltage which results in a loss of power and capacity. The lithium batteries have very little effect and will provide much more power and capacity. The lead acid pack generally gets only 50% of the rated capacity at the loads we are drawing in an electric vehicle. The lithium pack will have practically zero loss of power and capacity from this effect. I have been trying to decide between Thundersky batteries and CALB (China Aviation Lithium Battery) batteries. The CALB has more power for a given size, but costs a bit more for a given capacity. I really wanted to get the extra power, but I could not justify the added expense at this time, so I opted to order the Thundersky batteries. I also wanted to install 200aH batteries, and I could have installed the previous generation batteries in the car, but I wanted to use the latest generation pack. The problem with the latest generation is that they changed the dimensions of the batteries such that I cannot easily fit them into my existing battery boxes. There would be lots of wasted space and I would have to build more boxes in a different shape. Because I did not want to go to this effort, I decided to go with the latest generation of the 160aH batteries. I will have 20% less capacity in my pack, so instead of 120 mile range in the car I’ll be closer to 100 mile range, but I think that will be sufficient for what I am trying to do with this car. The original pack was rated at 235aH, but because of the peukert effect mentioned earlier it was more like 115aH of usable capacity. This means that in real world driving conditions I should see a 40% increase in range for the car. I never really had any range issues before, and I’ll certainly not have any after the upgrade. The batteries have to be ordered from China, and will take about 45 days to arrive in the US, so that gives me plenty of time to get the car prepared for the upgrade. Time to start cleaning the car up and pulling out all the old batteries.

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