Auxiliary Battery Pack

The following page is structured to define the auxiliary battery pack for MSXIV. This page builds off of the page created by Micah Black found here Aux Battery - MSXIV

At the moment, the auxiliary battery pack is designed to be used for the horn and driver fans. It needs to provide at least 12V and needs to be able to withstand current spikes of 3-4A.

Our previous battery setup of 10S 1P Turnigy 5000mAh NiMH cells (shown below) seemed to work well however it was mentioned that it was draining too quickly as we powered the car using the aux. battery during troubleshooting. If possible, evaluate the possibility of using the spare SLA 12V battery to power any troubleshooting power needs.

According to the guidelines, our aux. battery falls under the “Supplemental Batteries” section. According to 8.2.B, other battery technologies will need to be evaluated by Headquarters and details must be submitted before the 4.3.A.2 due date. If approved, use of the SLA will significantly increase the usage time of the aux. battery pack as well as the time between charge.

Another issue was the battery pack seemed to cut out while attempting to close the relays too early. This could be an indication that the cells in series do not posses equal amounts of charge. LSD (Low Self Discharge) cells hold charge better but do not posses the capacity needed for the aux. battery pack. Unfortunately, due to NiMH’s high discharge rate, this is not controllable without active balancing but it can be managed.

Because the pack will have all the cells in series, they carry the same current during charging. One way to address this issue is to provide a full charge (charge to capacity) to the batteries even if it means overcharging some cells and dissipating the extra energy as heat.

Decision:

Upon review of the NiMH 10S 1P battery made from Turnigy cells, it was determined that this is still the best choice. The batteries are:

• Easy to recharge

• Is allowed by current regulations to be an aux. battery (Li-ion not allowed)

• Allows for 45 mins of debugging time at full LV load (80W)

Product Specifications:

Link for Purchase: