Any Automotive Programmer here?
holly52
Posts: 3
I own a 2012 Chevrolet Volt, I am looking for a programmer that can modify the SOC - State Of Charge of my car main lithium Ion battery. In other words, I want to be able to charge my 16.5kw battery to full 100% and be able use it and deplete all the way to zero before the generator kicks on. Any help or other site suggestion would appreciated!
Comments
From a tips list here is the recommendation:
[h=1]Five tips for extending lithium-ion battery life:[/h]http://www.techrepublic.com/blog/five-apps/five-tips-for-extending-lithium-ion-battery-life/
[h=2]: Avoid completely discharging lithium-ion batteries[/h] If a lithium-ion battery is discharged below 2.5 volts per cell, a safety circuit built into the battery opens and the battery appears to be dead. The original charger will be of no use. Only battery analyzers with the boost function have a chance of recharging the battery.
[h=2]3: Allow partial discharges and avoid full ones (usually)[/h] Unlike NiCad batteries, lithium-ion batteries do not have a charge memory. That means deep-discharge cycles are not required. In fact, it's better for the battery to use partial-discharge cycles.
There is one exception. Battery experts suggest that after 30 charges, you should allow lithium-ion batteries to almost completely discharge. Continuous partial discharges create a condition called digital memory, decreasing the accuracy of the device's power gauge. So let the battery discharge to the cut-off point and then recharge. The power gauge will be recalibrated
The high and low tails are where the battery suffers damage during charge and discharge. And since this is not a straight line, there is not much to get out of the Lithium cell at the low end... just a big risk of having to replace the cells.
I suspect you need to learn more about the actual battery chemistry and the discharge and charge curves before you consider modifications. It is more than likely that the Volt was optimized in a reasonable fashion.
Above all, no battery is going to recharge without damage after being driven to zero... regardless of chemistry. In general, going below 50% of maximum charged voltage is going to upset the cell chemistry. There is a voltage region where charge and discharge do the least to wear out the cell and it is nearer the peak charged voltage.
The problem could be more that your gauges always indicate something less that 100% and more that 0% due to how they present the information... so you think there is more to be gained. That very flat middle of the lithium ion discharge line makes the calculation of how much charge is available very difficult to provide with precision similar to how much gas is in a tank.
If it was my car, I wouldn't dare reprogram the charging software.
1) The calendar life of the battery is adversely affected at higher state of charge. Calendar life is the life of the battery when it's just sitting there, neither charging nor discharging.
2) GM has designed the battery pack to meet OBDII requirements which are 10 years or 100,000 miles. The battery is a part of the "emissions system." Ten years is a very long time for any battery to last. So GM may be banking on some of the reserve to carry it through the CARB regulated lifetime by making some use of the reserve as the battery ages. When a battery ages it loses both capacity (energy) and power (increased resistance).
3) The battery at high state of charge is more prone to a "safety incident".
There are dozens of engineers at GM which worked hard to make sure hacking the system is not possible (or at least very difficult). If you raise the SOC past it's designed "full charge" set-point, no doubt over-voltage diagnostics and other similar protections will kick in and open the contactors of the pack. This type of battery from LG-Chem is not as affected by over discharge as it is by over charge. By over discharge I mean like going to 2.3 V per cell. 0 V per cell would be ridiculous. But nevertheless, it's not recommended to mess with GM's settings.
I am an automotive engineer who works on hybrid/electric vehicle batteries but not for GM.
Hacking into any system that has defenses against hacking really is dubious. The real risk is that you damage the system beyond repair and have lost your resale value in the car.