Solar car cover

Post by **Richo** » Fri, 28 Nov 2014, 20:45

500W is only 2 standard panels.
1.3kWh is probably too big for this application.
I'd think the Lithium Titanate would be better value around the 500Wh and would be smaller.

Post by **crustovich** » Sat, 27 Dec 2014, 04:27

Ok, after badgering the Parking Manager for a few weeks, I got a very enthusiastic "I will put it on the wish list" answer to my Power point request, so it looks like the Solar Car cover is the main (only)game in town.
The things that have made me "pause reflectively" on this project have been the cost ,the size of the setup, and the time to set it up each time.
I can get 400w (4*100w rigid panels) that will fold up to fit in the boot and fit on the roof OK, at a reasonable cost ($500) on Fleabay which is a start.
It strikes me that we are then converting DC to AC to convert back to DC to charge the drive batteries. It would save a lot of cost and equipment to tap straight into the Cars BMS from the solar panels, however I appreciate this would negate the warranty on the car, so we have to go the "long route".
For this setup to be usable, I would need everything external to the car, and preferably attached/hidden under the solar panels. From what I can see of the Battery/sine wave setups, this is not going to be possible (though I couldn't find an example of a 500Wh Lithium Titanate battery).
I've also drawn a blank on finding out what the minimum wattage figure that will keep the charger interested is.

Post by **crustovich** » Tue, 30 Dec 2014, 04:18

Richo, Can you point me in the direction of where I can get info on 500Wh Lithium Titanate batteries, Ebay draws a blank, or maybe I'm looking for the wrong thing.

Thanks.

Post by **Astroboy** » Fri, 02 Jan 2015, 04:16

I just submitted a note to Melbourne Airport supporting the addition of charge facilities.
I used their contact us page.
Hope it helps move the idea higher on their wish list.

Post by **crustovich** » Fri, 02 Jan 2015, 04:38

Thanks Astroboy, appreciate the support.

Post by **Richo** » Wed, 14 Jan 2015, 20:48

crustovich wrote: Richo, Can you point me in the direction of where I can get info on 500Wh Lithium Titanate batteries, Ebay draws a blank, or maybe I'm looking for the wrong thing.

Thanks.

LTO-1865-Rechargeable-Cell-2.4V-1300-mAh
I probably wouldn't go on these US prices as you would be paying for China to US shipping and their margin before US to Australia shipping is added.
160 cells would be 500Wh.
They are a PCB mount 18650 standard sized battery.
The cycle life of 3000 seems conservative as other manufacturers claim 10x that.

Post by **Richo** » Wed, 14 Jan 2015, 20:52

Although I doubt you can get them - here is a LTO battery made by Toshiba.

Toshiba SCiB
Implies 100% DOD without damage.
No thermal runaway.
10k+ cycles

Post by **crustovich** » Thu, 15 Jan 2015, 13:12

Thanks Richo,
The Toshiba unit looks good, with it's size, shape and ability to withstand temperature, it may be able to fit under one of the solar panels?
The technology looks like a real step forward in batteries.
Be interested to see what price they come up with when it's released.

Post by **Richo** » Thu, 15 Jan 2015, 20:51

The main issue is most shelf life of batteries suitable for ev's is about 10 years.
or 3000-4000 charge cycles for a daily charge.
So a battery claiming 10k+ cycles isn't that useful.
Except for UPS or multiple charge cycles per day - which is why they would be good in your application.

For a traction pack they aren't that great either as they are heavier that other Lithium cells.

Post by **Richo** » Thu, 15 Jan 2015, 20:55

If you are making a "12V" battery these would probably be more what you are after.

2.4V 45Ah LTO Battery

Post by **Adverse Effects** » Thu, 15 Jan 2015, 21:39

Richo wrote: If you are making a "12V" battery these would probably be more what you are after.

2.4V 45Ah LTO Battery

i would not buy them
there info dont match there pic
Super long cycle life 2.4V 45AH lithium titanate battery

Post by **Richo** » Fri, 16 Jan 2015, 20:34

Adverse Effects wrote:i would not buy them
their info don't match there pic

True.
But I would say don't buy "from" them.
It's more likely the battery picture is wrong from slackness rather than fraudulence.
The 2.4V 45Ah is LTO pretty common.

In any case 5 of the 2.4V 45Ah would make a nice 12V 540Wh battery.

Here's one with a more accurate label

http://www.alibaba.com/product-detail/r ... 51224.html

Post by **crustovich** » Sat, 17 Jan 2015, 02:55

They do look good, would it be feasible to mount them under one of the panels or would the heat be a problem?
Also has anyone purchased stuff through Alibaba? What''s the process, (I notice the second link requires a minimum purchase of 50)?

Post by **crustovich** » Sat, 17 Jan 2015, 02:59

Just to explore all options, If I can access the BMS for the drive battery, is there a chance I can plug the panels directly into the DC side of this ,avoiding the Battery/Inverter setup all-together or is my electrical ignorance showing?

Post by **T1 Terry** » Sat, 17 Jan 2015, 03:34

crustovich wrote: They do look good, would it be feasible to mount them under one of the panels or would the heat be a problem?
Also has anyone purchased stuff through Alibaba? What''s the process, (I notice the second link requires a minimum purchase of 50)?

looking through the specs the max charging temp is 45*C, not much use in Aust unless the system also has a forced cell cooling system. If you have ever measured the summer temp inside a closed up vehicle even the 65*C for LiFeP04 cells is borderline.

T1 Terry

Post by **Adverse Effects** » Sat, 17 Jan 2015, 03:46

crustovich wrote:Also has anyone purchased stuff through Alibaba? What''s the process, (I notice the second link requires a minimum purchase of 50)?

i have on 3 different times and 2 times i was ripped of with total junk with no warranty after you click the button saying you have revived the goods

and the help desk simply said "sorry there is no mention of a warranty on the sellers site so nothing can be done"

and the seller on one of the times wanted to charge me the full price of the unit and 1/2 the original postage cost to replace the control board

i carnt even copy and past the messages back and forth because they delete them after 3 months including the order list

the last one exploded the 3rd time i plugged it in and i got a hell of a shock

Post by **crustovich** » Tue, 20 Jan 2015, 20:48

Considering I am at the testing/viability stage of this project, and LTO battery assembly (if I can get them) is going to be north of $500, what is the cheapest battery setup I can get that will last me 2 to 3 months (100 cycles)? Or will it require a different inverter and/or give different results using a cheaper/different battery chemistry?

Post by **antiscab** » Wed, 21 Jan 2015, 16:23

crustovich wrote: what is the cheapest battery setup I can get that will last me 2 to 3 months (100 cycles)?

In this application (If I understand correctly) you are using the 500Wh battery to buffer the faster 2400W EVSE charge rate against the slower 250W solar charging.

So the 500Wh battery will have to do 32 cycles to transfer 16kwh
you could try getting some nimh cells from a vectrix (30Ah), they would hold up long enough to do a proof of concept

Post by **crustovich** » Wed, 21 Jan 2015, 16:54

It will be 600w of solar panels, and a normal charge (from flat) seems to be around 10kwh for the car.
I have some lead acid 12v17ah batteries left over from my electric scooter would they work for testing purposes?

Post by **antiscab** » Wed, 21 Jan 2015, 17:47

they would probably be ok, though they may not last long in that application

I would try it out with the free batteries you have before buying some lithium

Post by **crustovich** » Wed, 21 Jan 2015, 19:20

That's good news, as I have 4 of them! (knew they would come in handy one day...)
Now between the panels and the batteries, is a 20A one of these what I need?
http://www.ebay.com.au/itm/5-10-15-20A- ... 3cdc3a1081

Post by **Adverse Effects** » Thu, 22 Jan 2015, 04:42

crustovich wrote: That's good news, as I have 4 of them! (knew they would come in handy one day...)
Now between the panels and the batteries, is a 20A one of these what I need?
http://www.ebay.com.au/itm/5-10-15-20A- ... 3cdc3a1081

ahhhh before you buy one of thos you may want to do some research in to them

in 30 sec i found out that 99% of them i looked at where simply not even able to carry 500watt and a lot of them failed the first time plugged in

this sort of thing may be better

MPPT Solar Charge Controllers

Post by **crustovich** » Thu, 22 Jan 2015, 16:04

Adverse Effects wrote:in 30 sec i found out that 99% of them i looked at where simply not even able to carry 500watt and a lot of them failed the first time plugged in

Thanks Adverse effects, this is why I defer to the superior collective intellect of the group. I spent a couple of hours searching this and without knowing specifically what I was looking for did not find what you did in 30 seconds!

The site you directed me to raises another issue with my Lead Acid test system, as it differentiates between Lead Acid and Lithium MPPT's, which I haven't seen anywhere else. Is there a difference?

As far as the size of the MPPT,I could not find a max wattage limit (any where near my 600W requirement) if I am using 6x100A panels with a max power voltage of 18V 600/18 = 33.3 so am I looking for a min35a rated MPPT or 2 20A units?

Also T1 Terry mentioned in a previous post that I may not need an MPPT, though the mechanics of it went a bit over my head?

Sorry if my questions seem pretty basic/ignorant, I'm learning as fast as I can

Post by **T1 Terry** » Thu, 22 Jan 2015, 18:08

Hot solar panels don't put out the maximum output at the STC rated voltage (18v in this case) it's more like 15v to 16v. How do you plan to switch the inverter on and off? If you use a Plasmatronics Dingo 20/20N and drive a solid state relay (the ones J Car sell are good value for money as far as capacity v time they last) there is a wiring diagram on the Plasmatronics site on how to wire up the relay, then program the "G" terminal to turn on at say 14v for lead acid and off at 12v and drive the small 12v power switch on the inverter using the Dingo's "G" terminals, so the battery reaches 75% SOC before turn on and turns off at 50% SOC, this should get around 700 cycles out of the battery before it dies.

T1 Terry

Post by **crustovich** » Sat, 24 Jan 2015, 00:13

Thanks Terry, the Dingo looks good, I can't see anything in the specs that specifies battery chemistry, so I assume I can use it for my test Lead Acid and later reprogram it for the LTO's when I get them?
Also you mention the solid state inverters from Jaycar, are they the Pure sine or the standard inverters in 800w?