[Hilux144!]

Hi,

I'm converting an old Hilux pick up and am grappling with the battery pack design in terms of best configuration and BMS:

144 Volt system (HPEVS AC51)
Generation 1 Leaf Batteries
All in one single box on the back of the pickup

I'm not an electrical engineer so I want things as safe, simple and easy as possible. Ideally, plug & play, off the shelf and happy to pay the $$.
The 2nd hand leaf cells here in NZ are only $3.5k per pack of 48.
Weight not really an issue so will consider more modules to get better range, also there is no desire to optimize to the nth degree battery performance (apart from reliability and safety)

I would welcome any suggestions as to set up and BMS recommendations.

Thanks,

 

[brian_]

(HPEVS AC51)

Where are you planning to mount the motor? Directly replacing the engine, adapted to the original transmission?

Generation 1 Leaf Batteries
All in one single box on the back of the pickup

I'm not sure where you would put this single box. If the motor is in the stock engine location, or the stock transmission location, there will still be a shaft from the transmission or motor to the rear axle. Wouldn't that force the battery to be placed in at least two boxes, one each side of the shaft (and maybe one more under the hood or behind the rear axle)?

If you are planning to put the battery box on top of the pickup bed floor, that would work... but it seems like a shame to waste all of the functional space when there is so much volume under the bed floor to be used.

 

[brian_]

The 2nd hand leaf cells here in NZ are only $3.5k per pack of 48.

Is that 48 cells (which is 12 modules, or one quarter of the Leaf battery) or 48 modules (192 cells, the full Leaf battery)?

 

[Hilux144!]

Where are you planning to mount the motor? Directly replacing the engine, adapted to the original transmission?


I'm not sure where you would put this single box. If the motor is in the stock engine location, or the stock transmission location, there will still be a shaft from the transmission or motor to the rear axle. Wouldn't that force the battery to be placed in at least two boxes, one each side of the shaft (and maybe one more under the hood or behind the rear axle)?

If you are planning to put the battery box on top of the pickup bed floor, that would work... but it seems like a shame to waste all of the functional space when there is so much volume under the bed floor to be used.

Brian,
I have directly replaced the ICE using the CANEV adapter plate, so still running the gearbox, clutch, etc.

Yep battery box will be on top taking up loadspace. Agree not ideal but it works for me (the vehicle will be a basic commuter / hobby) and I wanted things as simple as possible with the batteries and high voltage cabling.

 

[Hilux144!]

Is that 48 cells (which is 12 modules, or one quarter of the Leaf battery) or 48 modules (192 cells, the full Leaf battery)?

Brian,

I have the full Leaf battery - 48 modules.

Thanks

 

[brian_]

I have the full Leaf battery - 48 modules.

Thanks
I assume that you will be rearranging the Leaf battery into 48s4p instead of 96s2p. You have a choice of making two 24-module strings and paralleling them (like the Wolftronix setup for his pickup), or paralleling at the module level.

 

[Hilux144!]

Cheers Brian - The WolfTronix layout is kind of exactly what I was after.
I presume my HPEVS will work ok with up to 160Volts?

What about the BMS - his Leaf BMS alteration is something I am just not capable of doing. Is there an off the shelf unit that would work with this?

 

[brian_]

I presume my HPEVS will work ok with up to 160Volts?

What about the BMS - his Leaf BMS alteration is something I am just not capable of doing. Is there an off the shelf unit that would work with this?

This is where you need forum members with more relevant experience to contribute...

 

[tortuga]

Has anyone looked into reprogramming the leaf BMS? I am pretty comfortable with electric and soldering but I wonder why take the drastic step of replacing the CPU on the BMS board like Wolf did?
It would be be more 'off the shelf' if we could reflash the cpu on those leaf BMS computers.

 

[PAXtss]

My modest comments.
I have done a conversion with Gen 1 leaf batteries and am working on one with Gen 3 batteries.
I am a plug and play person.

There are two ways to get where you want:
The first one is to parallel at the lowest level by putting groups of two modules in parallel and then put the modules in series Kevin did that here when he combined two Leaf batteries. http://www.diyelectriccar.com/forums/showpost.php?p=805721&postcount=8

Hopefully that came through. He used two hole and four hole connectors.

The other way is to do what Wolf did with making 144V packs in series and then paralleling the two packs -

To decide which to do is dependent on other things- One is BMS - The first one uses half the number of BMS (40 for your 144V) The second uses double (80) the BMS and Wolf has an ingenious way of doing this using the Leaf BMS system. This is way too technical for mortal people like me.

At 144 volts you will not be using all the Leaf Modules. 40 out of the 48.

Another option is to make three smaller packs - 16 modules each which is nominal 118V which will get you full Leaf battery power. These can be parallel at module level and you will only need 32 BMS taps This is what I would do myself if I were to re-power my truck
which is my first conversion- a Mazda pickup which I used the AC51- I set it up with half a Leaf battery at 96V - actually less. We use it around town and to launch our sail boat. lots of power but range is only 30miles- works for us. This motor strarts dropping out at something like 5 or 6,000 RPM although it will go up to7/8,000. so you probably need a transmission with it. it has awesome torque - pulls my 4,000 lb boat and trailer plus the truck up the launch ramp. I used off the self for everything.

The other thing to check is maximum voltage that controller will handle. If I read the HPEV site correctly the controller will take 170Volts. 40 Leaf cells would be 168 Volts charged.

 

[Hilux144!]

Note:

I have just replaced the ICE using the CANEV adapter, so still have the gearbox and clutch.

I've chosen to put the battery on the tray to simplify things.

 

[Kevin Sharpe]

Has anyone looked into reprogramming the leaf BMS? I am pretty comfortable with electric and soldering but I wonder why take the drastic step of replacing the CPU on the BMS board like Wolf did?
It would be be more 'off the shelf' if we could reflash the cpu on those leaf BMS computers.

iirc the Leaf BMS uses a different micro controller than the one Wolf uses on his daughterboard. He did explain his decision in one of his videos but I think it stems from the fact that the Leaf micro controller firmware is locked and can't be reflashed.

Wolf will install his micro controller and firmware into a Leaf BMS if you send him one. I think he's waiting to verify the firmware in his truck before announcing pricing for this upgrade service. We plan to use it in one of our Leaf based conversions. iirc I paid 50 USD last time I purchased a Leaf BMS

 

[Hilux144!]

PAXtss,

Thanks for the info - can you please clarify how the 3 packs of 16 modules would be configured to get 118 Volt?

 

[brian_]

Thanks for the info - can you please clarify how the 3 packs of 16 modules would be configured to get 118 Volt?

The modules are 2s2p, so they are 7.5 volts nominally (based on 360 V nominal for 96s cells, or 3.75 V/cell), but about 8 volts at fully charged. That makes 120 V (nominal) or 128 V (maximum) for 16 modules in series (plus any amount of parallel connection). 118 or 120... essentially the same thing.

Another option is to make three smaller packs - 16 modules each which is nominal 118V which will get you full Leaf battery power. These can be parallel at module level and you will only need 32 BMS taps...

That's two different alternatives, right?

1. three packs of 16 modules, then all packs in parallel (32 BMS taps per pack, 96 BMS taps total)
2. parallel sets of 3 modules, then connect 16 of these sets in series (2 BMS taps per parallel set, 32 BMS taps total)

 

[Hilux144!]

Brian,

I get alternative 1 above.

But your alternative 2 - I get 384V (assuming 8V per module)?

 

[brian_]

Brian,

I get alternative 1 above.

But your alternative 2 - I get 384V (assuming 8V per module)?

Parallel connections add capacity (in amp-hours), not voltage, so connecting three (or any number of) modules in parallel still gives you the same 8 V (max) as a single module. Connect 16 of those sets in series gives you 16 * 8 = 128 V (max).

384 V (max) or 360 V (nominal) is the result of connecting all 48 modules in series, as they are used in the Leaf.

 

[PAXtss]

HiLux144
For clarity I am talking about the way to parallel the modules into three parallel modules that are connected in series with three more parallel modules connected in series---- Such that you end up with 16 units of three modules, Like Brian said that gives 16 modules in series (16x7.5=120v) and the amperage for each three modules in parallel is 3 time one module.
In order to do this you have to reconfigure the packs - it is not hard but does take some thought. You have to take the packs apart and rearrange the modules
Here is a picture of the connection part of my 90-96 Volt pack in my truck. This is only two modules in parallel but you can add another module to make three.

The trick is to watch the polarity of the modules - they have a positive and negative terminal and a tap middle terminal -you want the negatives and positive terminals to be the same way for the parallel of the first modules where I have two you will have three.
Mine starts where the cable comes in on the lower right corner and there is a two hole connector that connects the negatives of the first two modules and then going up a two hole connector connecting the tap screws. The second set of double modules is reversed so the bottom side is positive and top is neg.. There is a four hole connector that connects the first two modules positive together and connects to the second two modules negative terminals- this puts the first two modules in series with the second two modules. There is a two hole connector that connects the second two modules tap screws together- only those two modules tap screws- you get a short if you connect to the first double modules. On the bottom side of the second two modules is the positive terminals - connected with a 4 hole connector to the negative terminals of the third set of modules. this repeats On to the last double module which has a two hole connector and a power connection from it.
In a triple parallel module set up you would have a three hole connector to start the three negatives with , a three hole tap connector and a six hole connector connecting the positives of the first combo module and the negatives of the second three module combo.
As a note- the BMS works at the cell level- the 4 volt level - so the BMS would go from negative terminal connector to tap connector and tap connector to positive- at terminals that are 3.5- 4 apart. Thus each combo modules need two bms connections so for 16 combo you would have 32 BMS taps.
If you draw it out on paper it should make sense.

I think I would do two packs of 8 - triple combos and then put them in series. One pack you should be able to make using the existing structural plates of the half battery pack. The other pack will take some more structural work. I can help you get the orange safety covers that mine has although I think Kevin modify the existing leaf covers.
I hope this is understandable.
Here is kevin's again http://www.diyelectriccar.com/forums/showpost.php?p=805713&postcount=7

 

[brian_]

Thanks PAXtss - that's a more clear illustration than I had seen before of paralleling the Leaf modules. In Kevin's thread, it's the posts following that one which show the bus bars: http://www.diyelectriccar.com/forums/showthread.php?p=805713#post805713

As described above and shown in these images, the centre tap point which gives the BMS access at the cell level (the smaller middle terminal) must also be tied together between the paralleled modules. Ideally, there is minimal current in these, as the cells should each pass the same current.

 

[tortuga]

iirc the Leaf BMS uses a different micro controller than the one Wolf uses on his daughterboard. He did explain his decision in one of his videos but I think it stems from the fact that the Leaf micro controller firmware is locked and can't be reflashed.

When I asked Wolf about the decision to remove the CPU a while ago he did not mention it being locked, rather just that it was easier for him to replace the CPU:
http://www.diyelectriccar.com/forums/showthread.php?p=902193#post902193

Inevitably the most plug and play option that I see (available now) is the Orion BMS or
Just keeping the Nissan leaf pack 'stock' and using a DC-DC converter to drop the voltage from 360 to 144 (or 120 in my case). Here is the converter I was thinking of:
http://www.brusa.biz/en/products/dcdc-converter/hvhv-800-v/bdc546.html
That way if your pack goes bad you can simply drop in another leaf pack.
Or rather any other ev pack.

Cheers
Tortuga