diy solar

diy solar

How do i capacity test with no equipment?

Yeah i'm going to look into getting a shunt next I guess. Atleast its something I will continually use.
 
Looking at THIS guy, but im not sure if it counts AH's and gives you the actual, or if you tell it the capacity and it counts down from that number?

I guess if I tell it the battery is 500ah, I deplete the battery to completely dead, and if it says 228AH remaining, that means I have 272ah available?
 
Looking at THIS guy, but im not sure if it counts AH's and gives you the actual, or if you tell it the capacity and it counts down from that number?

I guess if I tell it the battery is 500ah, I deplete the battery to completely dead, and if it says 228AH remaining, that means I have 272ah available?
@Lt.Dan - The easiest way to do it is with a smart shunt. Either the Victron smart shunt or the Thornwave Labs powermon-5s. Both have apps they talk to on your phone and show you the Ah or Wh in / out of the battery. I have both. The Thornwave Labs has more capability, but last I checked it is out of stock. I decided to use it instead of the Victron smart shunt which I had connected on my test bench for a couple of weeks.
 
Looking at THIS guy, but im not sure if it counts AH's and gives you the actual, or if you tell it the capacity and it counts down from that number?

I guess if I tell it the battery is 500ah, I deplete the battery to completely dead, and if it says 228AH remaining, that means I have 272ah available?
I have found this to be reasonably accurate and cheap:


Shunts are most accurate in the middle of their range, thus it is around 150 to 200 amp draw it will be most accurate.

Another cheap option for less current (I wouldn't use it for a load above 80 amps):


Just as an FYI, depending on the temperature, you get back 99 to 98% of the energy you put in. So these will drift over time, but not quickly and not by much.
 
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I have found this to be reasonably accurate and cheap:


Shunts are most accurate in the middle of their range, thus it is around 150 to 200 amp draw it will be most accurate.

Another cheap option for less current (I wouldn't use it for a load above 80 amps):


Just as an FYI, depending on the temperature, you get back 99 to 98% of the energy you put in. So these will drift over time, but not quickly and not by much.
The first one you posted is the same shunt (same brand too) as the one I posted, just with a different interface. I like the bigger interface though.

I like the idea of a Victron shunt, but damn! $200!!! Ugh...
 
I was looking at this battery monitor, as I like the screen to quickly look at. Also, its easier for my wife to understand, rather than teach her how to use an app. But the bluetooth is a viable option.
 
I was looking at this battery monitor, as I like the screen to quickly look at. Also, its easier for my wife to understand, rather than teach her how to use an app. But the bluetooth is a viable option.
Yes, I will eventually wind up buying one of those as well, primarily for the Bluetooth, and for the wife to look at.
 
The first one you posted is the same shunt (same brand too) as the one I posted, just with a different interface. I like the bigger interface though.

I like the idea of a Victron shunt, but damn! $200!!! Ugh...
Yes, Renogy sells one with the same interface (it is a good one). Renogy just marks it up $20. I went with cheap knowing I will eventually buy the Victron to go with the rest of the Victron equipment.
 
I have a victron smart shunt now, and I wanted to try to measure individual cell capacity before assembling a battery, but unfortunately I read the spec sheet on the smart shunt only goes down to 6.5v, what gives? Lol.
 
I'm trying to recall, it's been some time. I believe I powered the shunt off the battery ahead of the BMS.
There is some debate about it, but I agree that the shunt should be ahead of the BMS. That is, between the battery and the BMS. If power is cut off to the shunt, it loses track of the SoC of the battery, so if you put the BMS first, a low voltage disconnect will cause the shunt to forget where things are.
 
And I had it fused also, it's slowly coming back to me, it's been a year since I tested that pack.
 
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