Very nice, great combination of drive and car, I've been looking for a cheap Fiat 127 to pop an Agni into myself. The 127 is the smallest car you can actually fit a double bass into
What size battery pack do you think you'll be able to squeeze in?
My plan is to use 26 Lifepo4 150Ah packs. They would be located in the front and in the back. But as you know that involves alot of $ so I guess I will start of with lead acid 50Ah just to get everything up and running.
From the graph I have find, a 50Ah lead battery will be rated at 20Ah when you discharge it at 2C (100A). 100A x 72v is just around 8hp!
So, because the 50Ah battery will cost 600-900$ (100$-150$ each) and because you can only use around 15-20 Ah of those cells, if it' just to do some test, you can maybe keep an eye on small LifePo4 cells.
For example, 26 cells 38120s 10Ah will cost around 400-500$ and 26 cells 40160s 16 Ah will cost around 700-800$.
Maybe this 20Ah: http://www.ev-power.eu/?p=p_46&sName=lifeypo4-cells-(3.2v)
I used 7 Kg of headway 10 Ah in my Smart fortwo to do some test. That worked great.... for short travels at low speed!
It's just an idea!
You got a good point. Testing with low amp lifepo4 also gives me a chance to learn more about bms and charging. Ideal would be to be able to use the cells from test in parallel wither real pack, but i guess the discharge C would be a problem.
What about pouch cells? Those are minimal in size and weight, what is the draw backs?
What are your recommendations regarding bms? It would be nice to have a bms and a charger that can communicate.
I'm testing with a small pack of 20ah A123 pouches, 100lbs of battery gives me about 30km and good power and a top speed over 120km/h. I've also tested with 50lbs of battery and I get less range and speed, but works very well.
These cells are great because even a 60ah pack lets me draw 1000A without destroying anything.
How far and how fast would you get with 50-100lbs of lead?
by the way, on seats you can get very light aluminum shell seats in either high or low back by Kirkey.... at SummitRacing, or direct from Kirkey. I also found some nice vintage design seats by Corbeau.
A new update on the build. I've been playing around with the Kelly and found some undocumented features when it comes to regen. I'll post the findings in the right forum.
Hej Rikard,
Those 12V monoblocs look really interesting. The price is pretty good too. I guess if the individual cells are well matched at the factory they should stay closely balanced without any cell-level balancing. The only thing I would be concerned about is making sure there is little temperature variation across any single block that might cause drift between the four cells. I would be tempted to put a heat shield or thin layer of insulation between the motor and the ends of the blocks that are closest to it. Please let us know how they work out for you.
Malcolm
I was a bit skeptic in the beginning, but the guys at ev-power.eu provided a lot of data like discharge rates and I decided to try it. One thing that needs to be done in order to keep the blocks balanced is to charge them all in parallel a couple of times. Ev-power recommends the following approach for balancing: * During the initial charge
* After the first cycle
* After the first 5 cycles
* After the first 20 cycles
* After the first 50 cycles
* And then continue any time differences between batteries are noticed, about once every 50 to 200 cycles. That’s a good idea. I will put a heat shield to protect the batteries. Thank you Rikard
I see you've also bought one of the TC chargers from GWL Power. I've been looking at those myself. Do you know if the final output voltage is adjustable at all? My pack voltage will be midway between the voltages of the two closest models. I've downloaded the charger specification, but don't see any mention of adjustability.
TC charger (company itself) will alter output voltage per customers needs. They assume 3.65V per cell for LFP chemistry and will ask number of cells in your pack when you are placing your order. Other ending voltages are also possible. I believe ending voltage is adjustable in software and other hardware sets limits for voltage range. When voltage desired is out of range then different hardware is used.
I haven't asked if GWL Power can perform programming of chargers. I wish they could so chargers could be customized for any number of cells and not limited to most commonly used setups.
That looks very nippy for a 72V system. There's a lot to be said for converting a small, lightweight car. I really like the simplicity of this conversion. Have you any idea of the 0–80 kph time? Do you use all the gears or just a couple of them?
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