Q and A



I have had some questions on various parts of the ghost, so I thought I would give some answers.

Relay, Main Contactor:

For some reason these are open air contactors. The new one is sealed. I do not know why they are called contactors when they are just big relays!

These can be completely disassembled with a screwdriver. Normally I wouldn't want to take these apart, but I was having problems and had nothing to loose by attempting a fix. What is odd is that the relay still opened and closed. And even at 500 amps it had near zero voltage across the contacts (after I cleaned it up). There may have been a partial short in the coil that was causing an over current fault. I am told this has been known to happen.


Battery Charge Voltage

I am using Lithium Iron Phosphate batteries. These are very similar to Lithium Ion, but are much safer with the trade off of lower cost and slightly lower energy density. Because of the different chemistry, they will have a different charge and discharge profile from LiIon. Over time, the manufacture has learned that for maximum life, the final charge voltage is somewhat less than the 4.2 volts originally specified.

There are all sorts of equations and trade-offs in battery charging.
Charge/Discharge Rate Vs. Battery life and energy per charge
Final charge voltage Vs. Energy per charge
Energy per charge Vs. Lifetime Energy

And I am sure there are more. These are from an outfit in China and the data they have supplied is relatively sparse. As with much of the product from China, buyer beware.

I just found this on AEVA forums:


I have 4 in parallel and 30 in series for roughly 16 kWh of energy. This should be a final charge voltage of 108 volts. That is what I recall measuring a few weeks ago, so it looks good now. I'll have to double check to be sure.

For comparison, a Nissan leaf with a 24 kWh battery pack has 84 miles of range. I was getting over 100 miles range with a smaller battery size of 16 kWh. The aerodynamic improvements of the body should lower the power requirements when cruising. New batteries have higher energy density and will save weight. Plus I have room for a larger battery pack.



Chain Noise and Alternatives

Part of the problem with the chain noise (most or all?) has to do with the regenerative braking (the motor pumps energy back into the batteries when braking). The regen moves the chain tension from the top of the sprocket-chain to the bottom of the sprocket chain. There is a chain tensioner on the bottom for normal driving but when the tension shifts from top to bottom appears to be what causes the noise.

I have a few ideas on how to fix this, but time and money is limited. So for now it is good enough. I am open to ideas, even though I am unlikely to use them any time soon. Could adding a chain tensioner to the top part of the chain help?

Update on progress

Moving slowly. Adding attachment points for panels. Driving around every weekend. So far, so good. Just taking longer than I would like. :-)




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