Power Consumption for Dummies

How do you store and manage your electricity?
Magneto
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Post by Magneto » Mon, 01 Jun 2009, 18:19

acmotor

Than you for your input.

It sounds like it might be the time to upgrade to Lithium Ion batteries, if the cost has come down with the $AU rising?

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Post by Johny » Mon, 01 Jun 2009, 18:20

Magneto, in the meantime you could remove and bypass out the bad battery. That's what Coulomb meant by:
"While all this is happening, your EV may (or may not) be driveable, with less range and possibly a lower high speed limit.".

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Post by weber » Mon, 01 Jun 2009, 19:45

acmotor wrote: Replace now. Move on. There is no majic elixa !     Image   

I totally agree with acmotor here, and disagree with coulomb, but coulomb knows that. We've been through this before. Image
One of the fathers of MeXy the electric MX-5, along with Coulomb and Newton (Jeff Owen).

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Post by acmotor » Tue, 02 Jun 2009, 05:20

Magneto, I didn't suggest Lithium (although is is a very wise direction to go) as it is also expensive up front for both cells and BMS. (but many say better value in the long run)
There is also the physical mounting changes that may be necessary.
However if you can stretch the budget and carry out the electrical / mechanical work, you would not look back.

The compromise you can consider is to replace the faulty optima with a 4 x LiFePO4 cells (if they can fit) as a token toward a lithium future !
Say 4 x 90Ah Thundersky LiFePO4 or some similar technology.
There will be a bit of setting up the charger and BMS (maybe 2 separate units) but all doable. There is no problem mixing chemistries if there is suitable BMS in place.
I suggest this only because you may be reluctant to throw more good money after the optima option !Image

Having raised this idea, I am certain that some other forum folk will come up with suggestions !    Image

edit: kursed kieboored kan't spelle
Last edited by acmotor on Tue, 02 Jun 2009, 08:24, edited 1 time in total.
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Post by Magneto » Tue, 02 Jun 2009, 11:50

Thanks AC

I'll be costing out the Lithium OPtion today.

I should be able to make the configuration of the LI bank of batteries fit with minimal structural alteration.

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Post by EV2Go » Wed, 20 Nov 2013, 00:27

Ok I'm not the sharpest tool in the shed on the best of days and I have had lots of sleeps since I started this thread...but how did we get to solar panels???

I only posted in the first couple of pages because I got totally lost, so maybe it was woven in there somewhere, but I'm glad this thread was brought up again because I need to relearn everything I didn't know then.

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Post by Gabz » Wed, 20 Nov 2013, 00:37

who knows there are a couple of obvious spam accounts which are slow to be shut down.

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Post by Richo » Wed, 20 Nov 2013, 06:51

Yeah they obviously didn't bother to read the thread

I looked at the post and though "Australian standards".
A-H is pretty much irrelevant here...
Bout the only option we have is how much money you want to spend.
HI-JACKED Image

Not too sure if I mentioned anywhere but:

Volts x Ah x Cells x 0.8 = Wh useable for LifePO4 (80%DOD)
But only on day 1...
on day 2 it will be less.

So if you plan to use near the Wh limit every day it wont be long before it doesn't go as far as you want.
Even though it still has a lot of Wh left in it.

So plan carefully Image
So the short answer is NO but the long answer is YES.
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Post by EV2Go » Thu, 21 Nov 2013, 02:43

Looks like the mods have been and cleaned house :)

Come a long way from the Thunderskys I was thinking about way back when the thread started. Now looking at some of those 19.6Ah A123 pouches, and they will be configured 80S2P for 160 cells.

So lets throw some numbers at it...

3.65 x 19.6 x 160 x 0.8 = 9157.12Wh hmmm doesn't look all that big.
I'm hoping the consumption of the trike wont be overly heavy to give me a decent range.

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Post by jonescg » Thu, 21 Nov 2013, 03:00

I'd recommend you pass on the A123s. If you find an affordable A123 cell, it's probably a junked one destined for the recyclers. You can buy 100% legit A123 cells from the USA but the dangerous goods shipping is pretty painful. Moreover, LiFePO4 is yesterday's chemistry. A123 offers about 130 Wh/kg. There are far more energy dense cells out there, mostly using the Li(NiMnCo)O2 chemistry, otherwise known as NMC. These cells offer 175-185 Wh/kg in the large pouch format. Farasis in the USA and EIG in Korea are using it extensively. I think Kokam are using NMC chemistry, but Brett can correct me on that. Small format cylindrical cells are approaching 250 Wh/kg, but the discharge rate is very low. The problem of expensive shipping with all of them remains though - dangerous goods = expensive shipping.

Good luck with it!
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Post by EV2Go » Fri, 22 Nov 2013, 02:16

I personally don't see what al the fuss is about... unless they are dirt cheap why bother?, they seem to have a much lower cycle life and with such a low C draw rate I would need to carry another 50% batteries to pull 600 amps.

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Post by jonescg » Fri, 22 Nov 2013, 03:07

Cycle life is a bit of a red herring. A battery is a lot like a box of matches - there's no way of knowing if it will work unless you use it. So you rely on the laws of probability to get you through. 1000 cycles at 80% DOD is their OEM warrantee claim figure. In reality it could be closer to 2000, or 5000 depending on how you use it.

If I'm not mistaken, you're after a light weight, small volume, long range pack for your trike? If so, there are options for you. 5 C continuous is pretty good for an EV application I would think.

All cells will have a probability of failure, whether user induced or manufacturer induced. Generally the more you pay the more you get, but the probability of a dud still remains. Only the number changes. For example, everyone I know who has an EV with Thundersky cells has had to replace a few cells at some point, without exception. The same goes for sky-energy/CALB cells, although there are fewer of them out in circulation.

So I guess the best approach is to over-specify, under-use and pick the best components you can afford.
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Post by Johny » Fri, 22 Nov 2013, 15:26

The best price I can find on Li(NiMnCo)O2 is double the price of Headway LiFePO4.
I must admit that I am hoping that the LiMnCO chemistry gets down in price over the next few years but at the moment is excessive for a reasonabley priced DIY road car.
I also like the better safety of LiFePO4. They don't have to be housed in sardine tins like LEAF and iMiev.
On a road going trike, you are unlikely to be wearing fire resistant undergarments. Image

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Post by jonescg » Fri, 22 Nov 2013, 17:30

Indeed, they are expensive Image They are on their way down at least. I guess my point of view is that if you're going to commit a large sum of money to a DIY project, you might as well spend that bit more and get a car with plenty of range. Missing a turnoff can add 10 km to your drive - these things happen if you're a luddite like me who doesn't have a GPS... If you had that bit more range, you would be inclined to drive that bit further without the need for rigid charging plans. It's not priceless in the "Mastercard" sense of the word, but it's worth something.

NMC is as safe as LiFePO4. And LiFePO4 is also housed in sardine tins - cylindrical tins or large yellow plastic tins. The downside of pouches is that you need to devise a means of containing them, but isn't too hard but an extra expense you need to consider.

And you can always jump off a bike or trike, rather than being trapped inside!
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Post by EV2Go » Fri, 22 Nov 2013, 22:15

The main advantage for using genuine A123s is the peak C rating with 40ah cells I need to pull 15c for about 15secs to get 600amps (hoping it doesn't do 15 sec quarters) with a peak of 10c for 10secs I need to increase the pack by 50% which I may not have the room for.

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Post by Richo » Sat, 23 Nov 2013, 00:05

If A123 don't exist how can you get "genuine" A123 cells?

Are B456 still making the original A123's?
So the short answer is NO but the long answer is YES.
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Post by jonescg » Sat, 23 Nov 2013, 00:37

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Post by EV2Go » Sat, 23 Nov 2013, 02:00

Richo wrote: If A123 don't exist how can you get "genuine" A123 cells?

Are B456 still making the original A123's?
Please explain... I have been out of the loop for a while have A123 gone under?

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Post by EV2Go » Sat, 23 Nov 2013, 20:46

Upon reading more about the EIG batteries, I could perhaps get away with 80S3P of the 14ah cells. Need to do a few more calculation to see if it would fit physically but with an increase to 52ah it should give reasonable distance.

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Post by jonescg » Sat, 23 Nov 2013, 21:16

Bad news on the 14 Ah (LiFePO4)cells is that they only produce them with a MOQ of 5000. Their main product is the C020 cells. The vast majority of their customers want the best energy density on offer, so they only focus on the NMC cells.
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