Dual Battery Box - Mid contactors?

[rstevens81]

Hi, I’m starting to build a shopping list of things i need and i started thinking about the battery configuration.
I want to split my battery pack in 2 forward and aft for weight distribution reasons I started looking at what extra is needed, what i found with googling "HV Battery Wiring" scared me slightly.

Obviously you will always need a negative contactor, a positive contactor (plus pre-charge) and a fuse in each battery box however i have seen that a mid-pack contactor is not mandated.

I would want to put at a minimum;
on the 1st battery box contactors on the positive and negative, HV fuse
on the second battery box a positive contactor, pre-charge resistor and relay & HV fuse

I would be temped to add a negative contactor to the 2nd battery box for total isolation when off, but I’m probably being a little over zealous.

I would like some other people’s thoughts on this, preferably those experienced in building.

I stole this from zero ev's website (to be fair they do state "These are to be used as guidance and not as a direct how to")

[johnspark]

rstevens81, i am having 2 battery compartments too. I am using 4 contactors and a precharge one. So i am completely disconnecting power from all HV wires when the car is off. (I am doing this because it matches with my career as a protection engineer for 40 years).

[arber333]

Hi, I’m starting to build a shopping list of things i need and i started thinking about the battery configuration.
I want to split my battery pack in 2 forward and aft for weight distribution reasons I started looking at what extra is needed, what i found with googling "HV Battery Wiring" scared me slightly.

I would like some other people’s thoughts on this, preferably those experienced in building.

My thoughts are to keep a single quick disconnect or fuse in one box. The one that has easiest acces to. This will let you disconnect your battery serial connection and in turn you will be able to work on the cells. You do not need multiple disconnect points if you have a single battery line.

Thoughts on multiple contactors... well OEMs use two contactors. One for positive line and one for negative line. I only use one contactor on positive line. Its just because if i wanted to charge i would need to make a rather elaborate front to back HV wiring and i decided not to do this for simplicity sake.

For precharge contactor i use small 20A contactor that OEMs use either for precharge or to turn on the heater.

[JaniK]

In a Ford Focus Electric, the battery is split into 2.
Both Battery packs have 2HV contactors, bms slaves and 350A fuse in each pack in about middle of the pack series, that also is a safety disconnect that can be taken off for maintenance without opening the pack.
Only pack with BMS master has precharge and charge contactors.

I plan to use an e-golf pack divided into 2 packs in my car.
I am thinking that I would opt for no voltage between packs and since I have some contactors, propably will just make the packs with 2 contactors per pack. That will give me also the option to run the car with 1 pack if I feel the need to do so for any reason. Like the 1st. Test run.