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Battery pack voltage advice for EV datsun 1200

Posted: Mon, 17 Sep 2012, 17:33
by Brett_celicacoupe
Hi Jeff,

I dont think my ute has 1400km range.

sorry.

I am in NQLD

Battery pack voltage advice for EV datsun 1200

Posted: Mon, 17 Sep 2012, 17:49
by Johny
This website appears to offer some info. including a neat graph.
http://www.elearnaid.com/opd35fortoca.html

Battery pack voltage advice for EV datsun 1200

Posted: Mon, 17 Sep 2012, 17:55
by Johny
This guy recorded a huge amount of info. about his EV yellowtops.
It appears the charger(s) were at fault for some early failures.
http://www.oocities.org/s_medhus/optima.htm

Battery pack voltage advice for EV datsun 1200

Posted: Mon, 17 Sep 2012, 17:57
by Brett_celicacoupe
excellent!

so far i havent let the pack voltage drop below 158v (12.15v/cell - 45% dod according to link)

cheers

Battery pack voltage advice for EV datsun 1200

Posted: Mon, 17 Sep 2012, 20:26
by Jeff Owen
Brett_celicacoupe wrote: Hi Jeff,

I dont think my ute has 1400km range.

sorry.

I am in NQLD

My fault, like most people I keep forgetting that Queensland does not finish at Noosa.
We did have a ute conversion drive down to Brisbane from Mackay for the annual AEVA conference last year, so it is possible.

In your photos, the batteries don't appear to have a management system, will you be fitting one?

Jeff Owen

Battery pack voltage advice for EV datsun 1200

Posted: Mon, 17 Sep 2012, 20:40
by Simon
My Optima D34 batteries where charged to 14.5V and then charger went to float mode. After switching off the charger the Voltage would drop down to 12.9-13.2V. I think 0% SOC would be 10.5V?
The Optimas only lasted 9000km in my car and that was with shallow discharges to 70-60% SOC. You should consider 12.0-12.2V at rest "empty" because the voltage sag gets worse the lower you go.

Battery pack voltage advice for EV datsun 1200

Posted: Mon, 17 Sep 2012, 22:10
by Brett_celicacoupe
Johny wrote: This guy recorded a huge amount of info. about his EV yellowtops.
It appears the charger(s) were at fault for some early failures.
http://www.oocities.org/s_medhus/optima.htm


the 2 links you posted have different values in the SOC table. infact i think i did find both of these websites some time ago. i would be keen to see a third source of information.
Jeff Owen wrote:
Brett_celicacoupe wrote: Hi Jeff,

I dont think my ute has 1400km range.

sorry.

I am in NQLD

My fault, like most people I keep forgetting that Queensland does not finish at Noosa.
We did have a ute conversion drive down to Brisbane from Mackay for the annual AEVA conference last year, so it is possible.

In your photos, the batteries don't appear to have a management system, will you be fitting one?

Jeff Owen


no battery management - test cells with a MM after 100 charges?


Battery pack voltage advice for EV datsun 1200

Posted: Mon, 17 Sep 2012, 22:16
by 4Springs
Congratulations on another EV on the road!
Looks nice and tidy under that bonnet. Any more details/pics? I'd like to see how the rest of the batteries are mounted.
Whenever I see someone using clear plastic I can't help but wonder how much cleaning they'll have to do...

Here is the zener balancing that I used on my lead-acids:Zener Reg Balancing
I've done a few kms now, must go and measure the voltages to see how balanced they are.

Battery pack voltage advice for EV datsun 1200

Posted: Mon, 17 Sep 2012, 22:20
by Brett_celicacoupe
Simon wrote: My Optima D34 batteries where charged to 14.5V and then charger went to float mode. After switching off the charger the Voltage would drop down to 12.9-13.2V. I think 0% SOC would be 10.5V?
The Optimas only lasted 9000km in my car and that was with shallow discharges to 70-60% SOC. You should consider 12.0-12.2V at rest "empty" because the voltage sag gets worse the lower you go.


gday simon,

how far did you typically discharge your optimas? what voltage per cell?

cheers

Battery pack voltage advice for EV datsun 1200

Posted: Mon, 17 Sep 2012, 22:25
by woody
a4x4kiwi built some for the electrolux:
Simple Zener Diode Lead Acid Balancers

Battery pack voltage advice for EV datsun 1200

Posted: Mon, 17 Sep 2012, 22:26
by Brett_celicacoupe
4Springs wrote: Congratulations on another EV on the road!
Looks nice and tidy under that bonnet. Any more details/pics? I'd like to see how the rest of the batteries are mounted.
Whenever I see someone using clear plastic I can't help but wonder how much cleaning they'll have to do...

Here is the zener balancing that I used on my lead-acids:Zener Reg Balancing
I've done a few kms now, must go and measure the voltages to see how balanced they are.


i think most of the details are in this thread? let me know if there is anything else specific.

here are the rear 9 batteries. i have a fibreglass cover (work in progress) for them.
Image


I have 20 x 10w solar panels i am putting together as a hard cover for the tray.

cheers
Brett

Battery pack voltage advice for EV datsun 1200

Posted: Mon, 17 Sep 2012, 23:02
by Brett_celicacoupe
4Springs wrote: Congratulations on another EV on the road!
Looks nice and tidy under that bonnet. Any more details/pics? I'd like to see how the rest of the batteries are mounted.
Whenever I see someone using clear plastic I can't help but wonder how much cleaning they'll have to do...

Here is the zener balancing that I used on my lead-acids:Zener Reg Balancing
I've done a few kms now, must go and measure the voltages to see how balanced they are.


Thanks for that - it is simpler than i thought.

I just checked my battery voltages (almost completed charging) and they are all within 50mV of 12.95 with one at 13.00 and one at 12.55.

Battery pack voltage advice for EV datsun 1200

Posted: Mon, 17 Sep 2012, 23:18
by 4Springs
Solar panels - cool! And at 200W, would only take 34 hours to charge! I wonder if you could rig it so that you could tilt the hard cover towards the sun. Or it might not make much difference that far north?

NQLD means that you don't have to worry about the battery temperatures, so your battery boxes can be much simpler than mine.
NQLD might also answer the next question - what did you do for a demister? Not sure if you'd need one up there?
I considered that configuration of batteries, but Adverse Affects convinced me to put two of them under the tray. Made it much neater in the tray with only one row of batteries, but making the two under-tray boxes probably represented half the time/effort I spent on the build...

You were allowed to register it without the completed fibreglass cover?

Battery pack voltage advice for EV datsun 1200

Posted: Mon, 17 Sep 2012, 23:33
by Brett_celicacoupe
4Springs wrote: Solar panels - cool! And at 200W, would only take 34 hours to charge! I wonder if you could rig it so that you could tilt the hard cover towards the sun. Or it might not make much difference that far north?

NQLD means that you don't have to worry about the battery temperatures, so your battery boxes can be much simpler than mine.
NQLD might also answer the next question - what did you do for a demister? Not sure if you'd need one up there?
I considered that configuration of batteries, but Adverse Affects convinced me to put two of them under the tray. Made it much neater in the tray with only one row of batteries, but making the two under-tray boxes probably represented half the time/effort I spent on the build...

You were allowed to register it without the completed fibreglass cover?


research i have done so far leads me to believe a charge regulator is not neccesary as the panel current is less than 2% of the rated Ah. anyone had any experience with this.

I would like to keep things simple so the simple solution is to park it facing south, up a slight hill if possible.

yes it has a demister - it is a 200W item that was sold on ebay some time ago. i glued a piece of poly to the outlet and the datsun flex air duct fits on that. it is pretty weak though.

i went away from batteries under the tray due to time and complexity.

The fibreglass cover is made and it was registered with it on. i am still doing some work on it though to get it smoother etc.


Battery pack voltage advice for EV datsun 1200

Posted: Tue, 18 Sep 2012, 05:54
by Adverse Effects
4Springs wrote:but Adverse Affects convinced me to put two of them under the tray. Made it much neater in the tray with only one row of batteries, but making the two under-tray boxes probably represented half the time/effort I spent on the build...


but the extra work was worth it ? correct?

it just made total sense to me to use all that empty space and keep the tray for what it was meant for Image

Battery pack voltage advice for EV datsun 1200

Posted: Tue, 18 Sep 2012, 14:10
by T1 Terry
research i have done so far leads me to believe a charge regulator is not neccesary as the panel current is less than 2% of the rated Ah. anyone had any experience with this.
I'm typing as I'm thinking so bear with me.....
I might be able to help a bit here. With the solar panels the voltage that max current occurs is marked on the back of the panel (Vmpp) but that is in a lab using a light box and flash readings(STC, standard test conditions). In reality the 25degC isn't achievable in normal conditions, the sun gets the panel up to 45degC plus (NOCT, normal cell operating temperature)and the Vmpp drops by around 0.2v per deg over 25degC so the 18v Vmpp @ 25degC becomes 14v @ 45degC. The output current below the Vmpp remains reasonably constant but once over the Vmpp if drops off rapidly and drops as the heat starts to take effect, at the open circuit voltage there is nothing, in fact with even the slightest load applied it won't reach the Voc(Voltage open circuit).
What I'm trying to say in a very confused way is you must have a much higher combined advertised STC Vmpp than the end of charge battery voltage to allow for temp variation the solar cells will under go while charging and this has the potential to over charge the battery pack. On cold days with a good wind chill, 10 x 18v = 180v but at NCOT 12x 14.4v = 172.8v, you would get away with that but at 45degC 10 x 14v = 140v so it won't get it up to the 172.8v required for end of charge.
To effect a full charge via direct connection you will need another 2 cells, on the cold panel days 12 x 18v = 216v (*)resulting in the batteries turning into electrolysers once fully charged and the recombiners generating heat could result in thermal runaway eventually resulting in a stuffed battery pack, but at 45degC, 12x 14v = 168v, a reduced charge rate as it's over the Vmpp of the solar cells but it would get there..... you need at least 2 more cells and a regulator to be safe. A simple crude voltage sensitive on/off regulator will do fine for what you want but you could go all the way to an MPPT regulator but with a charge rate of around 0.5 amps at best via a straight connection the gain would be bugger all.
Another alternative is to use some sort of boosting system, then the 10 panels would work but of course a voltage control system would still be needed.

*would the 0.5amp charge rate be enough to create sufficient battery cell electrolyser effect to work the recombiners hard enough to create a thermal run away, the peak charging voltage drops as the temp rises so it's a self destruct cycle… I don’t know the answer to that one

Did that help or have I just added more confusion?

It did bring a tear to the eye to see a Datsun 1200 ute modified but an electric conversion was the best modification there could be and you have achieved a very neat looking conversion so I take my hat off to you, adding solar charging puts icing on the cake.

T1 Terry

Battery pack voltage advice for EV datsun 1200

Posted: Wed, 19 Sep 2012, 01:30
by 4Springs
Adverse Effects wrote:
but the extra work was worth it ? correct?

Yes, although at one point I certainly thought it was all too much work. Possibly it was when jacking up a 40kg battery from underneath the car into place, only to find that it was 3mm too big!
Everyone is surprised when I show them the tray, they all expect it to be full of batteries, so yes, it was worth it. Image

Battery pack voltage advice for EV datsun 1200

Posted: Thu, 20 Sep 2012, 04:23
by Simon
Brett_celicacoupe wrote:

gday simon,

how far did you typically discharge your optimas? what voltage per cell?

cheers


Hi Brett, Congratulations, nice job on the Datsun!
The average voltage per battery was 12.56V and average distance between recharges was 9.3km. I basically drove to work and back and recharged after work if I planned to go out later in the day, otherwise overnight charging.
Really disappointed I didn't get more km out of the Optima pack. Now with the CALB 60Ah cells I normally only charge every night or second night. Secretly hoping they die an early death so I can upgrade to the new CA grey cells!
Image

Battery pack voltage advice for EV datsun 1200

Posted: Mon, 04 Feb 2013, 20:30
by Brett_celicacoupe
Well i have been driving the car a bit lately and have now installed 20 10W solar panels on the tray.

For various reasons I am looking to sell the ute. I would be keen to get some advice in relation to where the best place is to sell the car given its electric? unfortunately i cannot sell on here until i post a few more times...

Regards
Brett

Battery pack voltage advice for EV datsun 1200

Posted: Mon, 04 Feb 2013, 22:34
by antiscab
i just updated your forum settings to allow you to post in the for sale section

Matt