Brendon_m Moke

Post up a thread for your EV. Progress pics, description and assorted alliteration
User avatar
brendon_m
Groupie
Posts: 140
Joined: Sat, 28 Oct 2017, 11:00
Real Name: Brendon McCarrol

Re: Brendon_m Moke

Post by brendon_m » Mon, 14 Jan 2019, 19:35

Yes, I've been watching your build closely it's all been very impressive.
Makes me feel bad because it's a polar opposite of my slap dash hack job.

francisco.shi
Groupie
Posts: 75
Joined: Mon, 17 Sep 2018, 16:30
Real Name: Francisco

Re: Brendon_m Moke

Post by francisco.shi » Tue, 15 Jan 2019, 04:41

I have seen a few conversions and I think the most difficult and messy part is the battery modules and the wiring. So I have been trying to design something that can help others to make conversions easier. Also unless you use a Tesla battery module the energy density and performance is quite low.
I am hoping to get a few people to use the battery modules I am making. It would make it cheaper if I could get a few modules done in one go. It is quite easy to change the configuration and size so I could easily make custom size modules without any extra design work.

User avatar
brendon_m
Groupie
Posts: 140
Joined: Sat, 28 Oct 2017, 11:00
Real Name: Brendon McCarrol

Re: Brendon_m Moke

Post by brendon_m » Tue, 15 Jan 2019, 07:01

Do you have ball park figures on costs?

francisco.shi
Groupie
Posts: 75
Joined: Mon, 17 Sep 2018, 16:30
Real Name: Francisco

Re: Brendon_m Moke

Post by francisco.shi » Tue, 15 Jan 2019, 08:49

I am hoping for about A$300/kwh for the complete pack without the BMS and about $200 for both ends.
The ends are the manifold for the water cooling which are also what you use to bolt the battery to the case. The cost of the ends is really a matter of how long you make the battery. I have made one module which is 1.6m long. So if you make one module instead of two shorter ones then you save the cost of the ends.
The BMS goes between the cells and it needs to be installed when the pack is made because you can not get to the inside cell tabs after the module is assembled. If you want to use a different BMS I will have to put the sense wires as I assemble the pack.
I still don't know how much the BMS will cost but I am expecting about $15 per cell for the active BMS (active meaning when it is in bypass mode it pushes the energy to the rest of the pack instead of dissipating the energy in a resistor) and there will be another board that manages all the cells and the battery as a whole with a contactor to disconnect the battery if it overheats or over currents. The benefit of the active BMS is that you can discharge all cells equally and use the energy instead of making heat so you get slightly more range. But I do not know how much more. The battery specs say the battery capacity is within 3% to 4%. So my guess is you could get as much as 3% more out of the pack.
At the moment I have 3 cells in parallel which give enough space for the BMS to fit in between the cells. This gives a 189Ah capacity. The cells are 63Ah each. If you need less than 3 parallel cells I will need to check if the BMS can still fit inside. For more than 3 parallel cells it should not be a problem.

Post Reply