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2000 Honda Insight, manual transmission
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Discussion Starter #1
I apologize if this particular LFP cell has been discussed as an NMH replacement pack in other threads, but I didn't see any other threads addressing this particular cell.

I had a 144V pack built (45s2p) for me using the A123 cells before A123 sold the cylindrical cell line to LithiumWerks. I'm working on having a BMS developed for this pack at the moment. I am familiar with the six Li-ion chemistries and BMSs, but not very much about the 1st gen Insight's electronics interfaced with the NMH pack. This cell is 2.5Ah, so a 45s2p pack will have around 742 Wh. Since it is capable of a max continuous discharge at 50A, 2p would be a max of 100A. Max pulse discharge (< 10-sec.) is 120A or 240A for 2p.

I don't expect the 10kW motor would have regen current more than 240A for more than 10-sec., so I chose this cell. For non-racing driving, the discharge rates will likely be less than 70A and charge rates less than 50A (I'm guessing). So, expected cycle-life should be over 3,000 to 4,000 full charge/discharge cycles if not exposed to 150°F (65°C) for too long.

After removing the NMH battery pack, there are two power leads (see below) about 18-20" behind the driver's seat that measures 250-490V when the car is running without the NMH pack. After you turn the engine off, that voltage slows decays to 0V, in time. What is the source of this voltage? The voltage decay reminds me of a capacitor.

The regen power comes from the 10kW electric motor when coasting or braking, right? Does the power from the generator go though this DC converter below and out the two power leads shown?

85959


Which sets of wires are necessary to be connected (besides the two power leads), in order for the LFP pack to work in concert with the car? I know these are very basic kindergarten questions, so please be patient. If this all works out, I can get you guys an LFP power pack for less than US$650 EXW China, in a soft-pack all laser-welded togther in 45s2p configuration, as shown below.

85960


Initially, I thought about using LTO, but the price for the grade-A cells are too expensive. The grade-B cell can probably work for this application, but my supplier felt the A123 LFP cells would perform just as well at a much lower price and much more compact.

Looking forward to some assitance. Thanks.
 

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Interesting and I wish you luck with your efforts.
However a few issues spring to mind.

Did you ask for advice before getting a pack built?

I assume the cell you are using is the one in the spec sheet below. pdf attached.

1) I think the pack voltage is too low for the IMA system.
50 cells IMO would be a better number and interfaces nicely with the stock BCM and a tap every 5 cells.
Your 45 cells setup low voltage may charge excessively and or refuse to operate the IMA correctly once the soc starts to drop.. 50s x A123 cells gives a more natural match to the cars NIMH operating voltage range.

2) Paralleled cells do not necessarily share current equally.
They might. But once one gets dicky in some way then the load/stress on the other rises.

3) The regen (charge) capability of your chosen cells is really low, especially when combined with 2) above.
You may kills cells with the insight 50A regen, I've done that before with borderline cells.
If you don't kill them quickly it may significantly impact cycle life or some other parameter, but not be apparent for some time.
Assume someone is going to be descending a massive hill with loads of regen all the way.

To answer your questions.

1) Yes the power from the motor goes through the MDM/PDU and out of those two leads into the NIMH battery switchboard.
2) Yes the MDM/PDU has big capacitors inside it.
3) You need lots of wires connected and systems in place for the car to operate.
You can't just connect up your lithium battery to those two leads it's much much more complicated..

I suggest have a look my early lithium conversions and what systems were required to enable the IMA to function.

Please explain exactly and in detail how you intend to integrate your pack with the car and what systems etc you will use. Then we can see what level of understanding you have about the NIMH systems and what support or advice will be needed.
 

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This might be one of the most terrifying posts I've ever seen.... ;) lol
 

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Discussion Starter #4
Wow, such a warm welcome for a newbie. I'm sorry if I said anything so terrifying. I'll remove this thread shortly.
 

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I think you misunderstood our concerns, we aren't being unwelcoming, so no need to remove the thread.

We are happy to help and advise, but have to establish a posters knowledge level so we can give guidance.

High voltage packs are dangerous and the car is complicated, lithium conversion isn't a walk in the park.
 

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Sorry, I certainly didn't mean to ruffle any feathers - it was meant to be in jest. The reason for my quip was that you seem to have put the cart before the horse, as it were. You had a lithium pack built without understanding the requirements. That's scary to battery people. ;)

So, let's start over. You have a lot of information to soak up.

The source of the voltage is the IMA motor; it's a giant permanent magnet alternator coupled to the crankshaft and produces voltage whenever the engine is running. The bits that live next to the IMA battery are the DC-DC converter and Motor Drive Module(MDM). The MDM is an inverter that converts the 3 phase input from the IMA motor to DC, and the DC from the battery into 3 phase to drive the motor.

I hate to be the bringer of bad news, but the cells you have picked are not adequate for this application, at least in the proposed configuration. At least they're LFP, so you're most likely not going to burn your car down if you decide to install them anyway...

The Insight's systems are kW based, not amperage based. The Assist gauge reaches full bars when the IMA system is outputting 6.5kW. Same with the regen gauge. The peak power is around 12kW for assist, limited to around 4 seconds in 2nd and 3rd gears. Regen can hit around 9kW, continuous. This translates to around 85A of assist and 50A of regen with a NiMH pack.

The Insight can sustain over 6.5kW of both assist and regen for as many minutes as your battery and terrain will allow. It appears the cells you have chosen are only rated for 10A continuous charge, so your pack is rated at 20A continuous charge with a peak of 40A for 10 seconds.

An equal or bigger problem is voltages...

The NiMH pack is 144V nominal, but you can't just throw a pack of different chemistry but with the same nominal voltage in there. A NiMH pack at true 100% SoC rests at 168V(for about a day). The car's maximum voltage is 192V; the NiMH pack routinely hits 184-188V under high current regen at high SoC. The Insight's lower voltage limit under assist is 120V; any lower than this and the car aggressively begins limiting assist current.

The pack you have built has a lower voltage limit of 90V and an upper voltage limit of 162V, a rather large mismatch when compared to the NiMH battery.

Really, we're here to help.. but like Peter says, these things can be complicated...
 

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Discussion Starter #7
Thanks for the info. So, if the LFP pack is 45s5p, then that should handle the current issues. What is the max voltage the motor can handle? If it's 192V, then I can do a 60s5p pack. That should cover both the voltage and the current maximums. This would mean that I'll need 219V to charge. 138V would be the minimum. If this will work, then I'll build one, and hope you guys have the electronics to interface with the car's controllers. If the DC-DC converter can jack up the output voltage, then 60s can be decreased to reduce weight and cost.

If using an LTO pack, then 80s will have a nominal 192V. If using the 2.9Ah cell with 60C max charge/discharge rate, then 80s1p should work (170A). It'll weigh around 12 kg or 26.4 lbs, cells only. Cycle-life around 20,000. 216V charging voltage, 120V min. pack voltage. Do you guys have the electronics for this type of pack? Thanks.
 

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Forget about motor voltages for now.
Keep it simple and use 50S. That's about the right voltage for your cells..

25S5P x 2 packs would be best.

Designed to fit inside a hollowed out stock NIMH battery case if possible.
If you have a nimh battery case take all the cells and supports out and do some measurements mocks ups to see what you can fit in it.

A 50S pack needs to be split in half for safety and to mate well with the Insight switch board.

I don't know what BMS you are planning but you don't really want one that has the current control built in.
You need simple logic high/low signals for over or under V, then the stock car electronics can do the controlling.
 

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Discussion Starter #9
50s x 3.2V = 160V (I know they advertise 3.3V, but 3.2V is the original clan, and my supplier prefers 3.2V too.)
25s5p x 2 = 2kWh (100% more than we need).
If 25s, then I can get an off-the-shelf BMS.
I'll have to build an aluminum case since 25s5p x 2 won't fit into the original NMH cells frame.
I'm going to look into the 70s1p LTO pack since the price will be 50% less than the LFP pack, thanks to the 60C.
Thanks, and I hope you have the interfacing electronics.
More updates later.
 

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Please include your Location in your Profile.
Thank you.
 

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Click on your avatar at the top of this page, scroll down to account settings, fill in location, scroll down and push "save". You are done.
 

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Discussion Starter #14
LTO cell candidate:

86007


I'm guessing you all are familiar with this cell. At 192V, it'll be 80s. If the vehicle's max discharge is 85A, then 1p can support up to 174A. 80s1p will yield about 556 Wh. If the vehicle is driven as hard as 85A out (29C), and 50A in (17C), at all times, then the pack life might only be around 10,000 full-cycles. With my easy driving-style, it'll last more than 75-years. I'll order one of these once you all can confirm that you can help me with the electronics interface. How much would all the new hardware cost?
 

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OK. So you have changed chemistry.
Please post a link to a spec/data sheet for those cells.

Your 80S pack still needs to be in two halves.

40S x 2 for ease of connecting to the NIMH switch board and safety.

The cost of your extra hardware will depend on what you have from the original system and how good you are at building/wiring/soldering etc.

What BMS are you going to use? Please post a link and full details.

Any reason you are not using the FIT 20ah LTO packs available cheaply from Greentec and well documented on here?
 

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Discussion Starter #16
Not including the batteries and BMS, just your electronics for this LTO pack to work with my 2000 Insight (for the above comment).

By the way, for those who favor LFP pouch cells, here is an overkill LFP pack using the A123 pouch cells: 50s1p (20Ah) = 3.3 kWh


86008


These cells have rather large robust connectors from one of my suppliers (see below), but would still fit in the NMH battery space laying down sideways:

86009


An aluminum case with cushioning material inside should keep this pack comfortable from the Insight hard suspension system.
 

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Discussion Starter #17
I couldn't find any LTO cell associated with the FIT at Greentec, but found this ad:

86010

If this is not the FIT pack, can you send the link?
 

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They are the packs.
Several people including me on here are already using them quite happily.

Not including the batteries and BMS, just your electronics for this LTO pack to work with my 2000 Insight (for the above comment).
I/we can't answer this question accurately until we know what parts you have from the original car, your level of expertise and technical knowledge etc.

However if you just need a 'BCM fooler' resistor matrix and some guidance on voltage fooling then maybe < $100

I strongly suggest you read through the various lithium threads on here to get up to speed with what has been done before and how it was achieved, what problems we discovered etc etc.

We did A123 20ah cells ten years ago. ;)

 

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Discussion Starter #19
If you were referring to the above LTO module, then it's a 64.8V pack with 12s 1.7Ah cells. To get to 192V, 3 modules in series will be needed (US$795) but will need to do some modification work to get to the two modules as you suggested. While this is a good price, the only potential issue is the unknown history of the cells. Their warranty is only 3-months. The two 40s1p LTO packs from my supplier will cost around US$750 + shipping but will have a 3-year warranty; also more compact. Here are more details of the Greentec LTO pack:

86011


If you have the adapters and/or the wiring diagrams, then I'll order two 40s1p LTO packs from my supplier, since I know they will be properly built and tested. My supplier's link: www.kokpower.com
 

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Don't rush. Spend some quality time as has been suggested doing background reading.
You need to soak up a lot of Lithium information from here to make the project practicable.
We can't help if you haven't done the background work or answered our earlier questions.
 
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