4S2P Battery pack project

[waiapasi2006]

Hello all.
I got these battery in from the long waiting list.....
These are 230AH eve Cells. A total of 8.
I had top balanced the cells to 3.65 v and built a single 4S pack for testing their capacity.
This is what I have below. I did build a small box to help keep the cells intact.
Yes, did stick them in a milk crate for easy transportation.









My test at first.
used a heat gun.
What threw me off was the 13A on the heat gun vs. what the Dally app was showing 130.7A.
The wat meter showed 1428 watt pulled from the inverter and the clamp meter 130.6A ( Almost the same from the dally mobile app)
I ran this test for about 10 minutes to see if the inverter will hold up.

My question,
Why is the Dally app showing 130.7A vs 13A?




But, I was surprised that everything was cold to the touch.

Edit: Thanks to Forum and everyone here I was able to take on this project!

 

[chrisski]

That is correct. Amps X volts = watts and the heat gun runs off watts:

=================

120 volts 13 amps = 1560 wats

12 volts X 130 amps - 1560 watts

12 volts X 12 amps = 156 watts

===================

EDIT: Seems a little off still. THe inverters I use have 15% losses, so you are showing very, very low losses, <1%. I would think the heat gun shows 13 amps, the inverter would push that out by pulling the 130 amps it needs from the battery pus another 15% (20 amps), so I would think the Daly shows 150 amps.

Second Edit: I have not done much “heat“ testing, but I run thick 4/0 wires for 155 amps for a coupe of minutes, and those wires do not get hot. If I dropped this down to 2 AWG, I think it would. 2 AWG is not rated for that much amperage.

 

[waiapasi2006]

To run a long term load on the same 4S battery, I charged them back up to 14.6V.
My second test was using my refrigerator.
The spec:


Inverter used with the same cheap wires:



These are the number I got as far as capacity goes for this set of battery.
Time: 29:12 Hours
Amp: 9.7
KW: 2.45 per meter.

 

[waiapasi2006]

That is correct. Amps X volts = watts and the heat gun runs off watts:

=================

120 volts 13 amps = 1560 wats

12 volts X 130 amps - 1560 watts

12 volts X 12 amps = 156 watts

===================

EDIT: Seems a little off still. THe inverters I use have 15% losses, so you are showing very, very low losses, <1%. I would think the heat gun shows 13 amps, the inverter would push that out by pulling the 130 amps it needs from the battery pus another 15% (20 amps), so I would think the Daly shows 150 amps.

Second Edit: I have not done much “heat“ testing, but I run thick 4/0 wires for 155 amps for a coupe of minutes, and those wires do not get hot. If I dropped this down to 2 AWG, I think it would. 2 AWG is not rated for that much amperage.

Second Edit: I have not done much “heat“ testing, but I run thick 4/0 wires for 155 amps for a coupe of minutes, and those wires do not get hot. If I dropped this down to 2 AWG, I think it would. 2 AWG is not rated for that much amperage

= At the time of testing the Pack, that was the only item that came to mind. I will definitely change those cheap wires that came with the inverter.
Still a work in progress.

I appreciate your feedback Chrisski.
Thank you.

 

[chrisski]

I still check voltage loss when I put wires on inverters and Batteries, but I have never found that to matter. I just make sure the wires can handle the ampacity. Recommend wiring for the lowest voltage of the system. TEsting we usually do is when the batteries are charged, but battery amperage skyrockets when the battery drifts towards the low state. 2.5 volts per cell comes out to a 10 volt battery. My 12 volt inverter has a 10.5 VDC low voltage cutoff. THat 2000 watt inverter could see 230 amps in that case. THat same 2000 watt inverter would Normally would be 180 amps on a full battery with float set proper.

THere’s lots of charts out there some better, and wire ratino as published by the manufacturer will trump this, but this is what I use for wire ampacity:


On a side note, those are the very same tiles in my kitchen. I would not be surprised if you are in central AZ also,

 

[John Frum]

Second Edit: I have not done much “heat“ testing, but I run thick 4/0 wires for 155 amps for a coupe of minutes, and those wires do not get hot. If I dropped this down to 2 AWG, I think it would. 2 AWG is not rated for that much amperage

= At the time of testing the Pack, that was the only item that came to mind. I will definitely change those cheap wires that came with the inverter.
Still a work on progress.
I appreciate your feedback Chrisski.
Thank you.

According to this reference a 2 awg wire would be in the neighborhood of 140F with sustained 155 amps.
140F water is near enough to scalding.

https://www.uglys.net/docs/default-source/uglys-documents/errata/UglysResidentialWiring2017_Errata_Page2.pdf

 

[waiapasi2006]

I still check voltage loss when I put wires on inverters and Batteries, but I have never found that to matter. I just make sure the wires can handle the ampacity. Recommend wiring for the lowest voltage of the system. TEsting we usually do is when the batteries are charged, but battery amperage skyrockets when the battery drifts towards the low state. 2.5 volts per cell comes out to a 10 volt battery. My 12 volt inverter has a 10.5 VDC low voltage cutoff. THat 2000 watt inverter could see 230 amps in that case. THat same 2000 watt inverter would Normally would be 180 amps on a full battery with float set proper.

THere’s lots of charts out there some better, and wire ratino as published by the manufacturer will trump this, but this is what I use for wire ampacity:

View attachment 70726
On a side note, those are the very same tiles in my kitchen. I would not be surprised if you are in central AZ also,

Yes, I downloaded the wire chart as a refence from the resources tab.
Based on the parameters of the Dally setting, that is what I see here as well.

 

[waiapasi2006]

According to this reference a 2 awg wire would be in the neighborhood of 140F with sustained 155 amps.
140F water is near enough to scalding.

https://www.uglys.net/docs/default-source/uglys-documents/errata/UglysResidentialWiring2017_Errata_Page2.pdf

Thanks SmoothJoey.

 

[waiapasi2006]

To add to this. I went ahead and made some busbars with some copper pipes I had laying around.
1/4" pipes flatten down. Not my best handy work at the first attempt.
I ran on those busbars on the batteries for 29+ hours to power the refrigerator. I checked in on them from time to time while running and they were cold to the touch.
I didn't see a draw of more than 10A per the dally app and the watt meter which could be the case. The inverter was warm, but I could leave my hands on the surface with no problem.

 

[waiapasi2006]

My plan now is to finally build the 4s2p packs in a box.
looking at 460A pack @ 12V (14.6V charged)
Should I double on the busbars I made?
Thank you.

 

[John Frum]

My plan now is to finally build the 4s2p packs in a box.
looking at 460A pack @ 12V (14.6V charged)
Should I double on the busbars I made?
Thank you.

I saw a 2000 watt inverter in your pic.
If that is the only load...
2000 ac watts / .85 conversion factor / 10 volts low cutoff = 235.294117647 service amps.
235.294117647 / .8 fuse headroom = 294.117647059 fault amps.

There are tables online for copper busbar dimensions by heat and ampacity.

Electrical: Busbar - DC Copper Busbar Ampacities

The following tables have been provided by the Alliance for Telecommunications Industry Solutions (ATIS), T1 Committee, and represent ampacities for busbar sizes and arrangements typically found in the telecommunications industry.

www.copper.org

 

[John Frum]

Note that heat shrink on the bars decreases their ability to dissipate heat.

 

[waiapasi2006]

I saw a 2000 watt inverter in your pic.
If that is the only load...
2000 ac watts / .85 conversion factor / 10 volts low cutoff = 235.294117647 service amps.
235.294117647 / .8 fuse headroom = 294.117647059 fault amps.

There are tables online for copper busbar dimensions by heat and ampacity.

Electrical: Busbar - DC Copper Busbar Ampacities

The following tables have been provided by the Alliance for Telecommunications Industry Solutions (ATIS), T1 Committee, and represent ampacities for busbar sizes and arrangements typically found in the telecommunications industry.

www.copper.org

Hello smoothjoe.
I did download most of these needed information from the resource tab. I just have to incorporate them now.
I appreciate your feedback.
Than you.

 

[waiapasi2006]

Note that heat shrink on the bars decreases their ability to dissipate heat.

This is good to know. I was going to add heat shrink to the ones I am working on, but not anymore.
Thanks again.