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Discussion Starter · #1 · (Edited)
Volt batteries safe parallel Wiring

I would like some suggestions on options for connecting Volt batteries into a safe parallel pack configuration. The pack will be for a golf/utility cart.

The following are some specs I would like from the pack.

  • 48V
  • 200Ah approx.
  • The physical size of 4 - 48V, 2kW volt packs
  • BMS (for safety “no fires”)
  • Low cost setup
Some information about the cart

  • Sevcon controller (PP745) 500A/50A(field)
  • 11hp Motor
I have already purchased volt batteries and struggled to find examples or someone using these packs in parallel. I would love to see examples, suggestions, or comments that others have to offer. Below is my first pass of a schematic but am unsure if it’s a safe option.
 

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Discussion Starter · #3 ·
Hi carterman,

Here is an interesting paper on the subject of parallel batteries/cells. http://elithion.com/pdf/BPC2012Elithion.pdf

I am also interested in the motor and controller you are using. Can you start a build thread or something to detail out the system?

Appreciated,

major
Thanks for the response. The paper started getting me to think of what is happening at the cell level in the pack. The main thing I am concerned about is a cell level short, which the paper does not cover much. Below is some interesting presentations on cell level shorts I found doing some research.
http://wenku.baidu.com/view/52f8aa09763231126edb1132.html
http://files.evbatteryforum.com/bat...sidering The Safety For Electric Vehicles.pdf
http://www.nrel.gov/transportation/energystorage/pdfs/45856.pdf

From what I found, the Volt LG cells have a technology called SRS, which prevents internal shorts. If this is the case, I may not need fuses to connect these cells in parallel. I was considering pulse relays and fuses as shown in the schematic as a way to prevent a fire if a cell level short did occur. I was doing this because I know other packs such as Tesla’s fuse each parallel cell. Would anyone have experience connecting the volt cells in parallel and would offer advice such as recommend fuses?

The controller spec are in the manual http://www.fsip.biz/Documents/Sevcon PowerpaK (SEM & MicropaK) Manual – with Calibrator Section.pdf


The motor is similar to this one
http://www.golfcartshopper.com/proddetail.asp?prod=GCT103265&cat=72
 

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Thanks for the response. The paper started getting me to think of what is happening at the cell level in the pack. The main thing I am concerned about is a cell level short, which the paper does not cover much. Below is some interesting presentations on cell level shorts I found doing some research.
http://wenku.baidu.com/view/52f8aa09763231126edb1132.html
http://files.evbatteryforum.com/bat...sidering The Safety For Electric Vehicles.pdf
http://www.nrel.gov/transportation/energystorage/pdfs/45856.pdf

From what I found, the Volt LG cells have a technology called SRS, which prevents internal shorts. If this is the case, I may not need fuses to connect these cells in parallel. I was considering pulse relays and fuses as shown in the schematic as a way to prevent a fire if a cell level short did occur. I was doing this because I know other packs such as Tesla’s fuse each parallel cell. Would anyone have experience connecting the volt cells in parallel and would offer advice such as recommend fuses?

The controller spec are in the manual http://www.fsip.biz/Documents/Sevcon PowerpaK (SEM & MicropaK) Manual – with Calibrator Section.pdf


The motor is similar to this one
http://www.golfcartshopper.com/proddetail.asp?prod=GCT103265&cat=72
It appears that is a series wound motor and not compatible with the SEM controller.
 

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Discussion Starter · #5 ·
Here is a picture of the actual one, the one from the net was probably wrong. From what I understand that cart comes with this controller and motor from the factory.
 

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Here is a picture of the actual one, the one from the net was probably wrong. From what I understand that cart comes with this controller and motor from the factory.
That looks like a SepEx motor. I'd remove the shunt from A2. It will cause trouble. Was your controller factory tuned to that motor?
 
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