Planing CanView and BMS+ conversion with lithium

[Mr-plugin]

Hello, I am planing to get rid of my Enginer Kit and doing a conversion with 40AH cells and a Canview system with BMS+, Anyone else here tried it yet?

[lopezjm2001]

It is normally done with up to extra 3 OEM Prius NiMH HV packs in parallel from other Prius's from the wrecker's yard. As far as I am aware nobody has tried using lithium battery packs in parallel. You would have to ask norm. The problem with using lithium is that the cells need to have a very high charging limit 15C as up to 120 amps can be pushed into the lithium battery pack during regenerative braking. NiMH can take the high charging current. The Prius battery ECU may have a problem with Lithium and throw DTCs. You could ask pEEF for advice as he has done something similar without using BMSplus.

[planetaire]

Originally Posted by Mr-plugin

Hello, I am planing to get rid of my Enginer Kit and doing a conversion with 40AH cells and a Canview system with BMS+, Anyone else here tried it yet?

Hello, Mr-plugin.

I have been using for one-two month bms+ and lithium cells in // with stock nimh and have a 2007 prius.

It works very fine now. Never got some dtc.

More informations here

Short description:

70 cells A123 20Ah each, serialy connected.
This pack is subdivided in 5, each 14 cells easily removable. => 4,55kWh
Total weight only 41kg (90 lbs).

Some pictures before connecting bms+



Only the lithium cells are grid charged. Just limiting end charge voltage near 3v5.
These cells are connected in // with the nimh only when driving, even when they are "depleted". So there are contactors (and fuse of course) between lithium and nimh.

Add of course a high voltage bms, bms+ and driving pleasure.

It is then possible to drive in 100% EV for more than 40km (25 miles) with an average speed of 42 km/h (26 mph). Energy usable is more than 4kWh.
Maximum speed in 100% Ev is 90 km/h ( 56mph).

Maximum electrical power:
-under 45 km/h (28 mph) 20-28kW.
-over 14 kW.

Engine can be used when you want. Just press accelerator pedal more.

This additional equipment can be totally removed.

I enjoy it

I agree with lopezjm2001. Only use lithium cell that can accept at least 100A regen for a few seconds.

[lopezjm2001]

That's great! Couple of questions:

1. What is the charge rating for your prismatic pouch a123 cells. They appear to be made in Korea. I see they have a discharge rating of 3C. Selling on EBay.

2. What are you using for a BMS to balance your cells.

Thanks.

[planetaire]

Hello, lopezjm2001

1) You have A123 20AH datasheet here

So during 10sec 1kW per cell. Total 70kW, more then necessary.
This would be more then a hard braking. I never see more then 25kW.
I don't really use more then 60-70A when braking.

2) I use a modified version of peter perkins bms with 0,3A balancing amperage.

[lopezjm2001]

Originally Posted by planetaire

Hello, lopezjm2001

1) You have A123 20AH datasheet here

So during 10sec 1kW per cell. Total 70kW, more then necessary.
This would be more then a hard braking. I never see more then 25kW.
I don't really use more then 60-70A when braking.

2) I use a modified version of peter perkins bms with 0,3A balancing amperage.

The A123 pouch cell data sheet is very vague. It is possible that the A123 cell is capable of a charge rate of 4C for a few seconds during regen braking although it will probably decrease the cycle life of the cell. Maximum battery life is achieved with a charge rate of 1C.

I noticed that your 5 x A123 cell boxes are made of PVC. I would have chosen metal boxes to help eliminate the chance of ignitability and flame propagation. Although PVC boxes are lighter and the clear lid is great to be able to see the BMS board without opening the box and the box is a lot lighter and is easier to remove. The other advantage of a metal box is that in the unlikely chance the cells are overcharged the metal box goes a long way to stop the pouch cells from expanding like a balloon and bursting the bag of the cell and leaking battery fluid into the box. Do not get me wrong I still think you did a great job. I guess you must have added up the advantages and disadvantage between using metal or PVC.

Just wanted to know what you are using For a 230Vdc charger?

Did you build your own Peter Perkins BMS board or did you buy it?

Thanks,

John

[Mr-plugin]

hello Planetaire, lopexjm2001
Thanks for the info. I plan on using CALB 40AH cells, they can take a 1c constant charge so I should be ok with the short bursts of higher currant. I am able to get additional OEM packs , but I do not think I will satisfied with the range, Using the 40AH cells (almost 9kw) I should be able to get a 40 mile range in ev. Planet, do you have any problems with arcing when engaging your contactor to the OEM pack? What charger did you choose? I built a master and slave circuit boards for using Celllogs for my BMS for high and low voltage control. I wanted to use the Mini BMS but at $900 for 70 cells it is a little expensive. I am trying the circuit boards with my Enginer system now.

Originally Posted by planetaire

Hello, lopezjm2001

1) You have A123 20AH datasheet here

So during 10sec 1kW per cell. Total 70kW, more then necessary.
This would be more then a hard braking. I never see more then 25kW.
I don't really use more then 60-70A when braking.

2) I use a modified version of peter perkins bms with 0,3A balancing amperage.

[lopezjm2001]

Originally Posted by Mr-plugin

hello Planetaire, lopexjm2001
Thanks for the info. I plan on using CALB 40AH cells, they can take a 1c constant charge so I should be ok with the short bursts of higher currant. I am able to get additional OEM packs , but I do not think I will satisfied with the range, Using the 40AH cells (almost 9kw) I should be able to get a 40 mile range in ev. Planet, do you have any problems with arcing when engaging your contactor to the OEM pack? What charger did you choose? I built a master and slave circuit boards for using Celllogs for my BMS for high and low voltage control. I wanted to use the Mini BMS but at $900 for 70 cells it is a little expensive. I am trying the circuit boards with my Enginer system now.

Hi Plugin,

You can use two contactors to engage the battery. The first contactor will put in a high power 10 ohm resistor in series with the battery to limit inrush current and arcing. Then the second contactor will bridge out the resistor. Use the 230 volt contact output to energize the 240Vdc Coil of the second contactor. I use this system to reduce inrush current and arcing in a high frequency generator 120MHz to seal plastic. It is simple and effective. It dramatically increases the number of cycles the contactor can energize before a contact is blown or welded together and thus increases the contactor's operating life.

[Mr-plugin]

I thought about the resistor but how do figure the wattage of the resistor? I am sure there is a way to figure it out with the resistance of the packs and voltage but that calculation is a little beyond me

Originally Posted by lopezjm2001

Hi Plugin,

You can use two contractors to engage the battery. The first contactor will put in a high power 10 ohm resistor in series with the battery to limit inrush current and arcing. Then the second contactor will bridge out the resistor. I use this system to reduce inrush current and arcing in a high frequency generator 120MHz to seal plastic.

[lopezjm2001]

Ok. Before you enagage the contectors what are the possible battery voltages of your NiMH and lithium pack. The NIMH could be as high as 240v at 80% SoC and the lithium could be as high as 70 x 3.35 = 234.5 volts. So inrush current could flow in either direction as current always flows from a higher voltage to a lower voltage. During EV mode the NiMH battery could be as low as 180 Vdc. Do the calculations. The worst case scenario is that if the resistor is underrated it will burn out and develop a open circuit.