UPDATE: Second pack deliberations… Lithium pack

The part of the project that arguably could make or break it. I have thought up two approaches to this issue:

#Buy the cheapest off the shelf batteries in Costco and experiment – run a series of on road tests and get and idea of range / capacity in the real world. From here I would have useful stats about increasing power / range.

#Buy high end batteries (Trojan look good) then put some real effort into getting the battery design right – and try to get right first time.

!!!Option 1, Costco batteries

Costco have a 12v / 115Ah Marine / Deep cycle battery for $84 – trying to determine the OEM so I can run the numbers with evconvert calculator.

Useful web link: http://www.evconvert.com/tools/evcalc/?s=b

Using 12 batteries = $1008 + GA sales tax (6%)

Brought 2 x Costco batteries purchased for measurements / experimentation

!!!Option 2, Using Trojan 6V

Requires 24 batteries @ $130 / each = $3,120

The most important consideration with the batteries is the potential range. I have settled on 144v in the previous discussion about controller and motor. Using 144v will drive using either 12 x 12v, 18 x 8v or 24 x 6v for the battery configuration.

!!!Option 3, C&D Technologies (Dynasty UPS) – “Max Rate”

David offered option for a set of 12 second hand C&D Technologies AGM cell.

Battery specifications:

12v, AGM, 138Ah capacity

http://www.cdpowercom.com/product/battery/vrla/pdf/mr12_490.pdf

Getting their first charge…

Planned layout

battery-layout-B.pdf

!!!State of charge calculations

|!Charge|!Volts per battery|!Pack voltage|

|100%|12.65+|152|

|75%|12.45|149|

|50%|12.24|147|

|25%|12.06|144|

|0%|11.85|142|

!!!Battery log / management system

Battery log – Manual measurements of battery voltages before and after various trips.

BMS – Design and work to build a automatic monitoring systems

!!!Journal entries

2009 08 11 – Took delivery of 12 x C & D Technology, Dynasty Series, “Max Rate” AGM batteries

2009 08 12 – Rigged up a parallel charging harness and to allow a low rate charge (2A) using a standard automatic charger (on AGM setting.)

2009 10 19 – Battery racks in place

!!!Battery log

|Date|>|2/11|>|3/14|>|3/20|4/25|>|4/26|4/28|5/22|

|Distance|>|10mi|>|23.8mi|>|34mi| |>|10mil| | |

!!!Watt/mile

|Date|12/16|3/15|3/20|3/21|3/25|4/26|4/27|4/28|

|Distance (miles)|26|23.8|34|34|26|10|10|15|

|Charge (kWh)|12.2|11.62|13.9|11.7|11.59|4.18|4.3|6.2|

|Watts/mile|469|488|408|344|445|418|430|413|

!!!Battery layout

| | |6|

|7| |5|

|8| |4|

|9| front ->> | |

|10| | |

|11| |3|

|12| |2|

| | |1|

|Cargo door|>|>|

Lithiumate Lite. Dedicated EV BMS with some very nice integrations.

User manual:

http://elithion.com/lithiumate-lite.php#Manual

http://lite.elithion.com/

Tied the warning lamp to the “Gen” lamp on dash, so I get early warning of potential issues.

SOC output is connect to fuel gauge on dash, so I get 20%-100% aligned to E – F on the gauge. Never want to go below 20% SoC, but nice to know I have a couple of “limp” miles even at E.

My legacy BMS (Home brew) is being upgraded – same principle but using Raspberry Pi reading the serial port of the Lithiumate.

Ordered 48 of GBS 100Ah, they come complete with bus bars, straps and handles. They are pre mounted as blocks of 4 cells (12.8v nominal).

Also ordered a Lithiumate Lite BMS to match the set. http://elithion.com/lithiumate-lite.php

From http://www.evolveelectrics.com

Also ordered a Acme ~DC-DC convertor to eliminate voltage sag while driving with all the lights and “accessories” on…