diy solar

diy solar

Capacity Testing Equiptment - Do I really need to Buy More?

MrM1

I'm Here, But I'm Not All There
Joined
Mar 1, 2021
Messages
2,421
Location
N. Central FL
Background:
While I wait for my LFP bank to arrive (just ordered so I expect 60-90 days) I am wondering about the importance of Capacity Testing and Do I REALLY NEED to purchase more equipment than what I already have. The bank will be an 8s2p, two BMS set up with 272ah cells totaling 544ah.

I currently have a Conext SW 4024 Inverter/Charger, Connected to LA batteries. Also have a MidNite Solar Classic 150 with the Whiz Bang Jr. The whole set up is tied together thru a Midnite solar load panel with a Shunt installed. I can right now see how may AHs I put in and take out of my LA batteries. The only issue may be that this can only be reset (as far as I know) when the batteries reach 100% SOC as determined by the Classic CC settings.

I figure once my LFP bank is Top Balance etc and set up. I could possibly load / capacity test the new LFP bank using my inverter and a big load (like 80amps) with my SW. And if I turn off the incoming Solar Array for the test, I could read the AHs removed via the network app Classic Monitor and/or the Midnite solar LAN PC app

Question:
So if I have all of this already, is it really necessary to purchase say a cheap 150w 200v 20a (or whatever) capacity tester or will what I have do the same thing and probably much faster because I can apply more load. Do I already have what I need to reliable do a capacity test?
 
Last edited:
Background:
While I wait for my LFP bank to arrive (just ordered so I expect 60-90 days) I am wondering about the importance of Capacity Testing and Do I REALLY NEED to purchase more equipment than what I already have. The bank will be an 8s2p, two BMS set up with 272ah cells totaling 544ah.

I currently have a Conext SW 4024 Inverter/Charger, Connected to LA batteries. Also have a MidNite Solar Classic 150 with the Whiz Bang Jr. The whole set up is tied together thru a Midnite solar load panel with a Shunt installed. I can right now see how may AHs I put in and take out of my LA batteries. The only issue may be that this can only be reset (as far as I know) when the batteries reach 100% SOC as determined by the Classic CC settings.

I figure once my LFP bank is Top Balance etc and set up. I could possibly load / capacity test the new LFP bank using my inverter and a big load (like 80amps) with my SW. And if I turn off the incoming Solar Array for the test, I could read the AHs removed via the network app Classic Monitor and/or the Midnite solar LAN PC app

Question:
So if I have all of this already, is it really necessary to purchase say a cheap 150w 200v 20a (or whatever) capacity tester or will what I have do the same thing and probably much faster because I can apply more load.
If you correctly top balance your pack then the battery capacity should be determined by the weakest cell.
As long as you are satisfied with the performance of the pack then be happy.
If not you may want to test cells individually.
 
If you correctly top balance your pack then the battery capacity should be determined by the weakest cell.
As long as you are satisfied with the performance of the pack then be happy.
If not you may want to test cells individually.
Yeah I already purchased the Load/Capacity tester Will Likes. Arrived Yesterday . I did think it might be handy to keep around to test individual cells as needed. But in thinking about it seemed like it would take forever to capacity test the whole bank.

I might just keep it as I got it via a gift card anyway.
 
Yeah I already purchased the Load/Capacity tester Will Likes. Arrived Yesterday . I did think it might be handy to keep around to test individual cells as needed. But in thinking about it seemed like it would take forever to capacity test the whole bank.

I might just keep it as I got it via a gift card anyway.
I have one too.
I used it as part of a non-traditional method of top balance.
 
I bought one of the cheap capacity testers in case I needed to test any “suspect” individual cells. I ran full capacity tests on each of my 12v banks through a shunt and inverter and they all tested fine. I thought about doing some individual cell testing also, but I figure it’s another opportunity to screw something up by overcharging or over discharge since the BMS isn’t there as a safety net.

The only upside I can see to doing the individual cell capacity testing is to better group my cells by capacity. I’m honesty not sure it would buy me much. Maybe if I got real fancy and tried to map out voltage/soc curves, i could do some real matching, but it would be a ton of work to do that manually.
 
Nube question for this group. I should be getting the capacity tester Will uses today. I want to use it to test an 8s 280ah pack. However, Will mentions specific wires and connectors he used to connect the tester to the battery.

What type of wiring and connectors do I need?

Also, what settings should I use on the tester for this type of pack?

Thx!
 
Back
Top