DIY Electric Car Forums > EV Conversions and Builds > All EV Conversions and Builds

riwe · #21 12-19-2011, 01:18 PM

Quote:

Originally Posted by mora

Good going. Very clearly written posts in your blog. 90kg of lithium is something like 8kWh? Good choice. It should give you good city range.

Hi Mora,

Thank you! It's more like 7Kwh, but I think it will be a good start.

riwe · #22 04-03-2012, 08:37 AM

Long time no see...

Well I'm back and this time armed with the skill to TIG-weld. 90Kg of LiFeYPO4 is now installed in the fiat.

Check out http://luigi500.blogspot.se/

Best regards

Rikard

MalcolmB · #23 04-03-2012, 04:44 PM

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

riwe · #24 04-04-2012, 03:14 AM

Hi Malcom,

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

MalcolmB · #25 04-04-2012, 05:17 AM

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.

riwe · #26 04-04-2012, 05:22 AM

Quote:

Originally Posted by MalcolmB

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.

Thats right! As far as I know the final voltage can not be altered. It might be that you can order one with a specific voltage.

Amp's can be controlled by CAN or by a 0-2v input.

R

mora · #27 04-04-2012, 05:37 AM

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.