300V pack for gas turbine hybrid

Chat about all things battery in here.
Need to know what type to use or size or capacity then again place your thoughts here
granada203028
Posts: 38
Joined: Wed Apr 30, 2008 5:03 pm
Location: Bristol, UK

300V pack for gas turbine hybrid

Postby granada203028 » Thu Nov 24, 2011 8:36 pm

I'm looking for a better pack for this project:

http://www.jetpower.co.uk/gtcar_home.htm

The turbine has a 208v 3 phase 400Hz generator which defines the buss voltage at around 300V. To get the project up and running, two 24 x 4.5Ah strings of UPS batteries were used, but now their power and to some extent energy are quite limiting.

So I’m considering NiMH or Lithium. I have developed the motor and battery controls which fully protect the pack. Float voltage, minimum discharge voltage and both charge/discharge currents are all individually regulated.

Two strings of 240, 10AH NiMH appear to be an option and don’t require individual cell battery management, for example:

http://www.batteryspace.com/nimhrecharg ... te1pc.aspx

http://www.ebay.co.uk/itm/D-Rechargeabl ... 8915790344

I’m familiar with lithium polymer and have converted a small motor bike to electric using 200, 10Ah Li poly cells. I did my own analogue battery management for this with 10 series groups i.e. 30 – 42V system. For the MG, power looks to be more important than energy, so LiFePO4 types are perhaps the best option. Particularly if they can get away without battery management or a very simple system. For the MG we are looking at 100 cells in series so the amount of work to repeat the analogue system I did for my bike would be prohibitive. For example:

http://www.batteryspace.com/LiFePO4-401 ... screw.aspx

http://www.ev-power.eu/index.php?p=prod ... 20ah-promo

Anyone got any suggestions, for example a LiFeP04 system with management scale able to 100 cells for reasonable cost. Budget 2-3K.

User avatar
retepsnikrep
Posts: 1387
Joined: Sat May 26, 2007 4:50 pm
Location: North Yorkshire England
Contact:

Re: 300V pack for gas turbine hybrid

Postby retepsnikrep » Fri Nov 25, 2011 6:51 am

Nice project 8) Is your budget for the bms only :? or for the pack and bms :lol: Sorry couldn't help laughing a little bit.

What is the max current it charges at?
What is the max current it discharges at?
What are the max and minimum system voltages?

Small size lifepo4 cyclindrical/prismatic do not stand large charge currents well in my experience unless they are A123 20ah pouch cells which are very good but expensive. If you use lithium you will need a bms and a good one especially if you use Lipo instead of Lifepo4!

If you used a Maximite or Picaxe master you could use four of my own BMS stacked 25 cell slave boards for a 100 cell lifepo4 system. A couple of days work to assemble the slave boards. Cost say £500 or £5 per channel might be a bit cheaper with bulk parts.

For the easy cheap solution I have a lot of panasonic nimh cells in 6 cell high current sticks which can take 50A charge & 100A discharge. 8) http://www.ebay.co.uk/itm/320788907644? ... 1555.l2649
I would rather see them in use than on my shelf so if you want to do a deal off e-bay we might be able to come to an arrangement. They are a doddle to assemble with 6mm bolts or threaded rod.
Regards Peter

Two MK1 Honda Insight's. One running 20ah A123 Lithium pack. One 8ah BetterBattery Nimh pack.
One HCH1 Civic Hybrid running 60ah A123 Lithium pack.

User avatar
PHEV
Posts: 123
Joined: Wed Mar 26, 2008 5:50 pm
Location: Peacehaven/Brighton

Re: 300V pack for gas turbine hybrid

Postby PHEV » Fri Nov 25, 2011 2:12 pm

Very interesting project..

Ive got some LiPo cells here capable of very high power (20C continuous), and with good energy density. I also have a small and cheap high/low voltage protection system with extremely low power draw. All in stock in the UK..

One thing you didn't mention was how important was cycle life? The cells I have are good for about 250-300 cycles before 80% capacity is reached.

If this sounds any good for you, drop me a line. steve @ jozztek.com
Last edited by PHEV on Wed May 22, 2013 6:25 pm, edited 1 time in total.
*Mazda MX-5, 300KW peak, 300v 20KW/h lipo pack, Soliton 1000A controller. 1100KG.
*Ducati SS twin Agni 80HP peak.
*Aprilia RS motorcycle, 500A controller, Cedric's AgniMotor, 96v 6kw/h LiPo pack, 130kg, 90mph.
www.jozztek.com

granada203028
Posts: 38
Joined: Wed Apr 30, 2008 5:03 pm
Location: Bristol, UK

Re: 300V pack for gas turbine hybrid

Postby granada203028 » Fri Nov 25, 2011 8:16 pm

Thanks for the replies, food for thought there.

We are looking for a 25 - 30KW contribution from the battery. So a suggested 100A limit for a pack with a system voltage of around 300V. The 24 x 12V lead acid system was float charged at 336V and draw restricted to limit depression to 240V. There is no regenerative braking, the expectation being you would have the turbine running so this does all the charging. Charge current can be regulated to a value much lower than the discharge if need be. When cruising there may only be 10 - 20A spare from the generator anyway.

Calendar life is more important than cycle life. The turbine is very inefficient so it is not really a practical vehicle to cover any distance in.

What sort of voltage do the NiMH and Lifepo4 drop to at 100A? I bought some supposedly 11Ah D NiMH off eBay but they were only 4.5Ah and got pretty hot at even 10A. Were supposed to be able to do 30A. Seller refunded me including the return postage which I was pleasantly surprised at.

The battery lives in the spare wheel well and the lead acid solution weighed approx 90Kg. So within budget I guess we would look to fill this space, with several strings to help power if possible.

User avatar
retepsnikrep
Posts: 1387
Joined: Sat May 26, 2007 4:50 pm
Location: North Yorkshire England
Contact:

Re: 300V pack for gas turbine hybrid

Postby retepsnikrep » Fri Nov 25, 2011 8:43 pm

Assuming you parallel at least two strings of 6.5ah nimh, 40 sticks in each string, you are looking at ~80kg for 300-350V approx at 13ah max capacity.

Drawing at 100A will give a 50A draw per string and probably a max of 8ah useful capacity.

Add another parallel string for 120kg and you will add at least another 5ah making a useful 13-15ah pack.
The peukert effect will be less as load is shared so you will get more out of each cell.

I can supply 120 sticks at £6.50 each collection only. No bms reqd. 8)
The cells sticks also have temp sensing strips so you can detect an individual overheating cell with a very simple circuit.
Regards Peter

Two MK1 Honda Insight's. One running 20ah A123 Lithium pack. One 8ah BetterBattery Nimh pack.
One HCH1 Civic Hybrid running 60ah A123 Lithium pack.

jjmouris
Posts: 13
Joined: Tue Nov 15, 2011 3:04 pm

Re: 300V pack for gas turbine hybrid

Postby jjmouris » Sat Dec 24, 2011 10:41 pm

http://www.youtube.com/watch?v=WX-_azD2 ... re=related

You might wonna look at the above video before it dissapears like their website.

It's a 400+ HP electric car using Lifepo4 cells. First they used Headway cells, now i think it's got 300 (100S3P) 20Ah A123 pouch cells. Lipo is more expensive and won't last as long as Lifepo4 but will give more instantanious power then the above. It's basically all up to how much you want to spend on it.

My experiance + long term research on cell discharge;
Lipo cells can take up to 100C for 2-3 seconds. 70C for 5 seconds. 30C for 50% capacity
Lifepo4 cells can take only 30C tops for 2-3 seconds, 10C for 5 seconds. Probably keep it at 2C for 50% capacity

Charging wise, i don't exceed 5C on Lipo but am confident they can do more. Lifepo4 is supposed to charge even faster and 10C is being done in RC applications.

With regards to cell balance. I think that even Nimh packs deserve a balance function and certainly it's well worth the effort to do this with Life or Lipo to be safe and enjoy a long battery life with peak performance.

How much power can the generator deliver? I think you would only need about 15-20KW to be able to maintain 70mph long distance. If you want to start and stop a lot without regen then obviously you could want more. The battery pack is just there as a giant capacitor.

Joe

EDIT; new website for the BMW; http://www.rimac-automobili.com/evaluat ... vehicle-11

nigel.tegg
Posts: 7
Joined: Tue Feb 02, 2010 10:21 am

Re: 300V pack for gas turbine hybrid

Postby nigel.tegg » Sat Nov 29, 2014 12:00 pm

As you need a high pack voltage, and not a great capacity, I would recommend using 3.7-4.0V Li-Po prismatic cells, such as EIG or A123. these give a very high gravimetric energy density, but need careful charging and heat management. Forget Lead acid. What peak and average current draw does your gas turbine require?

Nigel Tegg BEng
Prev: Principal Electrical engineer. TATA motors Indica vista EV prototype car (350V 200A, 130km/h)

granada203028
Posts: 38
Joined: Wed Apr 30, 2008 5:03 pm
Location: Bristol, UK

Re: 300V pack for gas turbine hybrid

Postby granada203028 » Thu Dec 11, 2014 9:35 pm

The project is on going and I have now just bought 64 Lifepo4 20Ah A123 look alike lipos to make a 200V or so pack. Tests on a small number bought previously suggest 10C should be possible i.e 40KW. Plus the 25KW from the engine should give the car reasonable performance perhaps approaching that of my Nissan Leaf.

The system voltage was changed from around 300 to 200 to work with a 11 in Net gain series motor. The generator is changed from star to delta. Home made controller aiming for 400A on the motor. This also limits battery charge and discharge and generator loading.

The cells were bought off Ali express approx £14 ea and appear of quality construction but I doubt they are really A123. They have some strange slight pock marking suggesting they may have been removed from packs as another contributor suggested. The Chinese supplier appears to have added on thin steel tabs of lower quality so connection clearly needs to minimise the length of these in circuit.

I plan to use a charge pump balancer as I have used else where with lithium ion batteries. Only monitor overall pack voltage. I can see a potential problem with routinely cycling 100A in and out. If one cell reaches full charge or discharge it could be damaged. Monitoring each cell and integrating this in my controls to then limit the whole pack is a huge task. Commercial balance circuitry appears to have only very limited power handing to divert for example charge to stop an individual cell over charging.


Return to “All things battery related”

Who is online

Users browsing this forum: Exabot [Bot] and 5 guests