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I'm thinking of creating a battery pack out of LiFePo4 cells for Nissan LEAF. I figured this is almost impossible from zero content I've found online regarding DIY batteries for LEAF.

  • Has anyone tried this before?
  • I'm thinking of modifying the Leaf BMS to accomodate LFP cells along with a seperate BMS to actually monitor the LFP cells.
  • Another approach I was thinking is to create a secondary battery pack and a DC-DC converter with CC to tap into the HV battery output of the main battery and feed it from the secondary battery (Range extender method)

Has anyone tried/have an idea about this? I'm flying blind.
 

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Your main problem would be that the energy density of LiFePO4 cells is poor compared with stock Leaf cells.
To make it to 360V you'd need 113 cells, each of which takes up only slightly less volume than the original Leaf cells (of which there were only 48).
You could definitely operate the motor on less than that but 300V is still 92 cells.

So you'd effectively need at least twice the physical space of the original Leaf pack to convert the car to LiFePO4.

Your range extender idea would suffer from the same problem since you'd need to still reach 360V. Either way you'd need to find some other type of batteries with better energy density.
 

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To make it to 360V you'd need 113 cells, each of which takes up only slightly less volume than the original Leaf cells (of which there were only 48).
The original-style Leaf actually has 192 cells in a 96S2P configuration. "Leaf cells" in the above refers to Leaf modules, which are 2S2P, so there are 48 of them.

Leaf modules are about 303 mm x 223 mm x 35mm, for a volume of 2.4 L and 3.8 kg, or 113 L and 182 kg. The lowest-capacity Leaf battery was 24 kWh, or 500 Wh/module.
To hit 24 kWh in 113 LiFePO4 prismatic cells, each would need a capacity of 212 Wh, or 67 Ah per cell @ 3.2 V. A CALB CA60 cell is close at 115 mm x 244 mm x 41 mm (for 1.2 L) and 2.0 kg... that's 130 L and 226 kg in total, for 21.7 kWh

So the LiFePO4 cell mass and volume is greater than the Leaf module mass and volume, even to match the lowest-capacity Leaf battery... but it might work in the Leaf battery case volume and might be acceptable in capacity. A problem might be that the CALC LiFePO4 cells are only rated for 2C discharge, which be only about half of the original Leaf's rated motor power. A bigger problem would be that these cells are probably more expensive than a good used Leaf battery.
 

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Apologies, I mistakenly used the word cells instead of modules. I was using a rough size calculation based on the volume of a particular LiFePO4 100ah "cell", assuming you wouldn't want to replace a degraded pack with one that had a lower capacity than the OEM one. The cell I had selected, the CA100Fl - also has a 3C discharge rate (according to EVTV anyhow), making it workable for the Leaf.

However, as you pointed out, cost is also a large factor.
 

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I'm thinking of creating a battery pack out of LiFePo4 cells for Nissan LEAF. I figured this is almost impossible from zero content I've found online regarding DIY batteries for LEAF.

  • Has anyone tried this before?
  • I'm thinking of modifying the Leaf BMS to accomodate LFP cells along with a seperate BMS to actually monitor the LFP cells.
  • Another approach I was thinking is to create a secondary battery pack and a DC-DC converter with CC to tap into the HV battery output of the main battery and feed it from the secondary battery (Range extender method)

Has anyone tried/have an idea about this? I'm flying blind.
Guy on YouTube put extra battery pack in parallel with the original battery then found out after x? Kw wouldn’t work even if extra battery pack was still good there are workarounds i heard
 

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So, while the density might not be as good, isn't the longevity better on the Lifepo4's? I'd be happy with 150 miles of range for $6,000 if that was true.

I know I've read that people have "hacked" some of the code on the leaf, but that is for sure not up my alley.
 

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So, while the density might not be as good, isn't the longevity better on the Lifepo4's? I'd be happy with 150 miles of range for $6,000 if that was true.

I know I've read that people have "hacked" some of the code on the leaf, but that is for sure not up my alley.
Hobbiest
LIFEPO4 is at best no different in reliablity than the leafs OEM

Far worse in bad situations
 

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So, while the density might not be as good, isn't the longevity better on the Lifepo4's? I'd be happy with 150 miles of range for $6,000 if that was true.

I know I've read that people have "hacked" some of the code on the leaf, but that is for sure not up my alley.
A BYD Blade Battery can easily manage 300 miles ... these are new battery cells and will give your car 3000 charging circles... but the question is... who has managed to hack LBC to accept say 144 3.2v cells ... each with 138 ah?
 

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I'm just starting to research the DIY EV prospects (note my low post number). However, I'm not new to Li batteries, nor to the electronics & algorithms of charging them. I have been able to figure out that the BMS stuff looks at the individual voltages of each cell in a pack (array), and has provisions to balance them. It monitors temperature on at least every couple cells to fault if over-temp conditions occur. The data collected by the pack module controller is then sent (CAN) to a master controller. The control algorithms account for use/discharge as well as charging conditions. Both require feedback from the pack module controller.

Building your own battery pack is relatively simple. Putting in all the necessary components and controls, and then properly conveying condition status to a master controller is where the sophistications arise. Maxwell (now part of Analog Devices), Texas Instruments, Microchip, and other companies offer battery management ICs. You may want to consider just how involved you want to get into creating your own battery "system". In the long run, I guarantee it would be much simpler to use what's already out there, already tested & proven, and what already integrates relatively seamlessly with other existing sub-systems. Nothing worse than building something that (according to the laws of physics works perfectly) just doesn't play well with the rest of the neighborhood.
 

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I'm thinking of creating a battery pack out of LiFePo4 cells for Nissan LEAF. I figured this is almost impossible from zero content I've found online regarding DIY batteries for LEAF.

  • Has anyone tried this before?
  • I'm thinking of modifying the Leaf BMS to accomodate LFP cells along with a seperate BMS to actually monitor the LFP cells.
  • Another approach I was thinking is to create a secondary battery pack and a DC-DC converter with CC to tap into the HV battery output of the main battery and feed it from the secondary battery (Range extender method)

Has anyone tried/have an idea about this? I'm flying blind.
Good news! Evs Enhanced out of New Zealand has been doing Leaf Battery swaps and upgrades. There are currently far along on design of a range of aftermarket Nissan Leaf replacement battery options. Check this video announcement
 

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Yes, the Leaf's cell voltages would be too high for any LiFePO4 cell. The proposal was to "modify" the Leaf BMS - it's not clear how the threshold voltages would be changed in the BMS.
just researching this thread. I have dreamed of putting 280 Ah LiFePO4s in a Leaf or an old Electric Toyota rav ... (Ithink they made a few), or an old car that make sense to convert. ... and you just clued me into the voltage limit idea ifor LiFePO4 in series. Does anyone know the Max series volt limit of the EVE 280 Ah LiFePO4 cells (got some at big bang for buck prices) ? ... vs what voltage are running those Leafs? I would love to look at some detailed wiring diagrams of the new technology the EV are using. I know the old EV running lead acid are not what I am interested in. ...m I think innovations will keep bringing us higher efficiencies as prices drop with the volume. I would like to know more about my DIY options, and desire to come across some good newer era EV wiring diagram. I do know the EV run 350vdc or more (up to 600vdc ? on some?), and some bigger advance solar system have batteries in that 350vdc arena (expensive batteries). Hi from Bill in Northern California
 

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280 Ah LiFePO4 well you can series as many as you want. sheer size of the battery pack would be the limiting factor Size and weight. for 350V nominal you are looking at 110 cells in series. a large pack 98.5kWh 110s1p
later floyd also in Northern Cal
edit 3630lb big so would squash the leaf.
 

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280 Ah LiFePO4 well you can series as many as you want. sheer size of the battery pack would be the limiting factor Size and weight. for 350V nominal you are looking at 110 cells in series. a large pack 98.5kWh 110s1p
later floyd also in Northern Cal
edit 3630lb big so would squash the leaf.
YES I could series the EVE 280Ah LiFePO4s up to 350vdc :+) ... That makes sense when I remember these 280 Ah LiFePO4s cell are power the less expensive EV in China. I calculate the same 98.5kW or power. Wondering what the Leaf battery is (almost remember). I calculate only 1300 lbs weight for 110 280Ah cells after weighing on at 11.8 lbs on my digital scale. Wonder if that lower weight would squash a Leaf? Do you know what the Leaf battery weighs.

... If the 280Ah LiFePO4 Cells are of interest to anyone here, I can mention after getting some compass bearings from my involvement with DIYSolarForum, and purchasing a couple of 8 cell sets via Alibaba that shipped sea freight from China to my US door address, with a Chinese Company handling all US customs hoop jumps and fees, ... then getting UPS or Fedex Tracking online (about a two month process) ... I have since order obtained additional EVE 280Ah LiFeP04s from Docan Power (a Chinese company) who has a warehouse presence in Texas. I paid about 20% more to get a better quality cell that got deliver in about 5 days instead of two months. I thought that was a good deal (for updating my home solar setup).
 

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opps I calculated at 11 kg 24.2Lb and didn't even get that right. don't know what I was thinking. off hand I don't know the weight of the leaf pack. You know how much room 110 eve 280 cells take up having a few of them. let me see if I can find the weight of a leaf battery pack.
later floyd
leaf battery ~(648 lbs)
 

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I'm thinking of creating a battery pack out of LiFePo4 cells for Nissan LEAF. I figured this is almost impossible from zero content I've found online regarding DIY batteries for LEAF.

  • Has anyone tried this before?
  • I'm thinking of modifying the Leaf BMS to accomodate LFP cells along with a seperate BMS to actually monitor the LFP cells.
  • Another approach I was thinking is to create a secondary battery pack and a DC-DC converter with CC to tap into the HV battery output of the main battery and feed it from the secondary battery (Range extender method)

Has anyone tried/have an idea about this? I'm flying blind.
I just did some calculations ... imagining 280 Ah EVE LiFePO4s in a Leaf or some other EV. for 350 vdc. ...taking 110 cells x 11.8lbs each (just weighed one) = close to 1300 lbs ... (not sure how that compares to Leaf Batteries ???) and would = a 30.8 kWh battery. ... Unless there was a lower price than I know about for bulk purchase. ...using some past puchases costing my $1k for 8 280Ah cells shipped sea freight from China, ...110 cell could cost $13,750 which seem very high at just doing some math. Might be a lower cost for that kind of bulk purchase. Looking at options while thinking ... When there is a Will, There is a Way !!! :+)
 
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