Hybrid Vectrix: Nimh+A123

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Sugarstorm
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Hybrid Vectrix: Nimh+A123

Hi there,

My Vectrix has a new life.
After running for two years with the original "cell killer" software, the current Nimh pack suffered a capacity reduction of about 20%.
Even after changing to a new firmware, the damage was there and I could do nothing about it. The range was about 50 kms, but not too fast. At a faster pace, the red light would come on at the 30 kms mark. And since I have a final climb up to my house, the pack was getting to a very low voltage (under 120v under load) each and every day.
Having a pack that wasn't dead but that required a huge self control with the throttle was a pain in the...well, you know! :D
I had to do something!
My option was simple. I had to upgrade do lithium! But let´s face it, it's a big investment. A 40Ah pack+conections+BMS+labour would cost me at least 3.000€. Maybe more. And that is with the weakest cells around. With the real good ones (A123), I was looking at a bill of 4.000€ or more.
I was getting sick with the idea of throwing away the Nimh pack that was still able to charge 2.5kw. What if...
Again Fuel Free Motos came to the rescue with a fantastic solution.
"Would you like to try a small A123 pack in parallel with your Nimh pack?"
YES!!!
The problem was how to fit the pack in the bike, without stealling space from the trunk. The solution was fantastic:

10276457_679598082089546_119627203_n.jpg
10306838_679598102089544_1774653155_n.jpg

Placing a PVC wire gutter to fit the A123 pack between the Nimh pack and both footrests:

10363290_686895794693108_1677969806_o.jpg

All protected by a in house built BMS. The pack is 40S3P configuration of 2.3Ah cells, giving an extra 917w to the pack.

The result?

Well, it looks like a new bike. I've done about 300 kms with it so far and it is...FANTASTIC!
Range is up 20 kms to 70 kms.
Aceleration is better, since the working tension was raised a bit.
The low limit (red light) of the pack was also raised from 115v to 118v, but I wasn´t abble to go lower than 122v. Very good.
I was able to do a 51 kms trip at 60kms/h average speed and still had 15/20 kms left in the tank.
The downside is that the bike is 9 kgs heavier, but since I ride 99% of the time alone, i'm not very worried about that.
And the best of all is that for a fifth of the cost of a full conversion to lithium I have a "new" bike, using the original Nimh pack.
And if I do convert to lithium in the future, I'll have more than 100kms of real world range!

All done by those fantastic guys at FFM!

LithiumVectrix
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Re: Hybrid Vectrix: Nimh+A123

Hi Sugarstorm, Great to see your Vectrix has a new lease of life. Those A123s will boost the current output of the combined pack. I sat down and did the maths and found a few problems. The 40s LiFEPO4 arrangement in parallel with the NiMH will be seriously overcharged as the Vectrix charges upto 151 volts. Have they changed the charging firmware? The bike cannot be run flat without damage to the LiFePO4 pack since run down protection is below minimum voltage for the pack. FFM could have avoided this by using the appropriate cells. This would be a 36s pack of Lithium Cobalt cells such as Panasonic NCR 18650 PD 2900 mAh or Samsung INR 18650 29E 2900 mAh. These are the standard cell used by people building high power E bikes and will be safe over the full range of 151 to 115 volts.
Just in case someone else makes the same mistake.

R
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Re: Hybrid Vectrix: Nimh+A123

Great work Rafael, congratulations.
I wish I had money like other people in this forum to hire your wonderful skills.

Sugarstorm
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Joined: Wednesday, February 22, 2012 - 09:37
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Re: Hybrid Vectrix: Nimh+A123

Hi Sugarstorm, Great to see your Vectrix has a new lease of life.

Thanks. It's a new bike!

I sat down and did the maths and found a few problems. The 40s LiFEPO4 arrangement in parallel with the NiMH will be seriously overcharged as the Vectrix charges up to 151 volts.

You should know that the charger doesn't charge up to 151v. The real final voltage is always 4 or 5v lower than what is shown. And 40*3.65v=146v, the perfect charged state for the A123 cells. And even if an overcharge was to occur, the BMS would cut the charge. No problem there. Don't worry. By the way, the cut off voltage was raised to 118v and the working voltage was also raised to 131v. More Power!!!

Have they changed the charging firmware? The bike cannot be run flat without damage to the LiFePO4 pack since run down protection is below minimum voltage for the pack.

Of course that the firmware was changed. The A123 pack is connected in parallel but it's diconnected when it has to be. If the lithium pack get's to a low voltage state, of course it will disconnect itself from the Nimh one. Otherwise it would die. If even I know that basic fact (and I'm not an EV specialist at all), do you really think a true master, like the one that did the work, would neglect that?

FFM could have avoided this by using the appropriate cells. This would be a 36s pack of Lithium Cobalt cells such as Panasonic NCR 18650 PD 2900 mAh or Samsung INR 18650 29E 2900 mAh. These are the standard cell used by people building high power E bikes and will be safe over the full range of 151 to 115 volts. Just in case someone else makes the same mistake.

With all due respect, this is a fantastic statement! FFM is using the wrong cells? AH, AH,AH!!!
You are the only guy I know that uses 18650 Li-on in a Vectrix. And you get away with it because of two simple things: 1- You have easy an very cheap access to them; 2- You use an absurd capacity in your cells (90Ah) so that the pack doesn't die after a few weeks. Ok, you have a 200 kms range, but for how long? And with a easy ride. Try to be agressive and your pack will suffer.
Even the best brands you mention (Panasonic/Samsung) might handle 2C discharge. Might! The recomended max discharge for these cells is 1C!
You have said before you don't expect to get a long life from your pack. Is that a good statement for an EV converter? C'mon man! "Hey, don't worry, if your pack dies just come back and I'll build another one". Is that what you say to your costumers? Poor guys. I wish them luck for the future.
Everyone knows that the Vectrix can draw as much as 210A from the pack.
The A123's I have can handle a 30C discharge rate. If each of the cells I have are 2.3Ahx3, that is 207A max discharge. I think it's enough :)
If FFM used 3 of yours 2.9 Ah cells, at a generous 2C, that is 17.4Ah. Do you really think they would last a day? 17.4Ah? Let me quote Meredith Grey "Seriously?"
Remember, each cell is composed of 40 batteries in series, but it's only 2.3Ah. x3 that is 6.9Ah. It's not a megacell of 90Ah like yours.
The A123 are by far the best cells you can put in a Vectrix. I know that because I rode one of those beasts already!!! And the diference it's like night and day! Do you know the feeling of coasting at 50mph, turn on the gas and the back wheel would just burst so strongly that you almost fall from the bike! Hey, that is A123 power. That pack could handle 1200Amps!!!
I guess the future will tell who is making the mistakes regarding cell choice.
Best of luck to you and keep us informed about the longevity of your packs.
I'll take my A123's any day!

R
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Re: Hybrid Vectrix: Nimh+A123

Do you know the feeling of coasting at 50mph, turn on the gas and the back wheel would just burst so strongly that you almost fall from the bike! Hey, that is A123 power. That pack could handle 1200Amps!!!

With those accelerations, may the "IGBT power" be with you, for a very, very long time...
LithiumVectrix
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Re: Hybrid Vectrix: Nimh+A123

Hi Guys,
Lets go through the last statement. The reason I quoted the A123 cells the wrong cells is because the voltage range does not match the NiMH pack. I asked if the firmware had been changed in my post. If NMC or LiCo cells 36s were used the voltage range would have matched. The charger does charge to 151 volts. NiMH batteries drop to 146 volts once charging ceases due to the higher voltage required for charging. If the firmware is changed, this will effect the charging of the NIMH pack. You stated that I only build Vectrix with 90 Amp/Hr packs. I build battery packs of 42 Amp/Hr, 60 Amp/Hr and 90 amp/Hr for Vectrix. My own 90 AmpHr scooter has 300Km range, is 3 years old and has done 36,000 Kms. My 42 Amp/Hr packs have a 119 Km range and weighs 36 Kg. All batteries come with a guarantee. The cells I use for Vectrix are the same as in the Tesla Roadster and do last longer than 3 years. The last Vectrix conversion I discussed on this forum was an NMC conversion using Leaf cells. Vectrix conversions is only part of the work I do. I build battery packs using NMC and LiCo cells in prismatic, 22650 and 18650 formats.
Now the batteries I mentioned for your purpose are Panasonic NCR 18650 PD 2900 mAh or Samsung INR 18650 29E 2900 mAh. These are LiCo power cells used in E bike builds. Take a look at Dr Bass posts in Endless Sphere. They are rated at 10C and suitable for bridging a Vectrix NiMH pack. They are not the CGR18650CG capacity cells used in my Vectrix battery packs. NMC which is the main battery used in electric vehicles is not available above 5C and not recommended for your build. The A123 cells used by FFM are 22650 cells. These are physically larger than the cells quoted above. I don’t understand why you quote 3P of 18650 cells as 5 or 6P would be used as they are physically smaller.
I have measured the current draw of the Vectrix during acceleration and it does peak at 210 amps. The Li-Ion pack is in parallel with the NiMH pack so the 2 packs share the current inversely proportional to each packs internal resistance. Your NIMH pack is sharing the current with the Li-Ion pack during acceleration.
The way to improve acceleration in a Vectrix is reducing the weight. The pack only needs to produce the current required during acceleration. Please read the following on EV album. This scooter is a 60 Amp/Hr build and is fast.
http://www.evalbum.com/4802
I am sorry that I have offended you. I don’t know the full detail of the FFM conversion and I should be more careful / tolerant about posting. I enjoy working on and using electric vehicles.

mpregal
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Re: Hybrid Vectrix: Nimh+A123

Congratulations Sugarstorm!!!!

If you travel to the north of Portugal (or the south of Galicia) let me know.

Great job FFM!

LithiumVectrix
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Re: Hybrid Vectrix: Nimh+A123

I want to comment that FFM has written some great firmware for the Vectrix scooter. They have features not avaliable from Vectrix or the Laird. They will customise the firmware for each customer.

Sugarstorm
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Re: Hybrid Vectrix: Nimh+A123

hi there LithiumVectrix,

I'm not offended. Don't worry about it. Just forget it. We just have diferent points of view.
The 36S6P pack of Panasonic NCR 18650 PD 2900 mAh you mention would cost me a small fortune. At 13$ each cell (the normal price on the web)*216=2800$ only for the cells, with no transport, import and handling taxes. And with no work done. So, just in material i'm looking at a 3500$ bill. And in all places these cells are rated at 3C. Under load at 10A (just above 3C) they all drop their voltage immensely.
My conversion cost was a small fraction of that price. With better cells. You can't beat that.
You use the Li-on cells because you have easy and cheap access to them. If instead you could buy A123, at the same price, can you honestly tell me you wouldn't use them?
Just catch a flight all the way around the world to Portugal, do a small test drive on a A123 Vectrix working at 137v, rated at 40hp, and then you will see what I mean :)
FFM have indeed done a custom firmware for my bike. Raised the working tension and reduced the cut off tension.
And they keep working everyday. No one dreams of what they will accomplish next. I'm sure when they achieve their next great breakthrough they will announce it to the Vectrix comunity.

Cheers mate, and let's all keep riding our V's!

R
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Re: Hybrid Vectrix: Nimh+A123

Sugarstorm, do you think installing only one series may hekp the NIMH? maybe Fuelfreemotors can make a mailable pack of only one series to add to our NIMH vectrix.

MRider
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Re: Hybrid Vectrix: Nimh+A123

HI Sugarstorm

You can tell to this community, that it's not all win win for FFM :P

What about some A123 conversions that has gone wrong with some water in the mix....

cevone
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Re: Hybrid Vectrix: Nimh+A123

Very nice and economical!

Can you send me the details of this conversion, I want to go this route! Please

Thanks

my email blaken_001 (@) yahoo

Jeff

just_looking
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Re: Hybrid Vectrix: Nimh+A123

I wonder can you tell me is it absolutely necessary to change the software on a vectrix charger if you swap over to 18650 cells or will the existing software charge the cells.

Also if I wanted to go over to a combination of 18650s and keep the nimh cells would I need to change the software or is there a way of doing this without changing the software.

R
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Re: Hybrid Vectrix: Nimh+A123

I wonder can you tell me is it absolutely necessary to change the software on a vectrix charger if you swap over to 18650 cells or will the existing software charge the cells.

As long as the temperature and voltage sensors receive correct data, the system will charge the cells. However, if you don't install a battery management system (BMS), I wonder if you want your vectrix to be destroyed by a fire...

If I were you, I'd install leaf modules, inside Vectrix boxes with pcbs, the canbus cable from charger to BMS, and a second generation BMS vectrix system. Also buy the peak canbus adapter to install official Leaf firmwares from Vectrix.
have a look at this guide:
http://service.vectrixparts.com/topics/209-vx-1-conversion-from-nimh-to-new-li-ion-batteries-sx-conv/

Also if I wanted to go over to a combination of 18650s and keep the nimh cells

The NIMH cells are in terminal state. Now they're too old, don't waste your time and money on them, unless 30 km of range is enough for you.

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