diy solar

diy solar

the easy way to keep your cells balanced is...active balancing

Balance 8P cells to 3.65V.
Let sit 10 days.
8S cells and charge. Within 30 seconds, peak cell at 3.8V and low cell at 3.36V. Got that high because the Chargery delay was set to 5 seconds.

No cell needed more than 6 minutes of individual 10A charging to hit 3.65V again. After that, they were fine.

10A for 6 minutes is 1Ah. 1Ah/280Ah = 0.36%. All cells required < 6 minutes, so I rounded down to 0.3%.
Isnt that an abnormal high self discharge rate? ??
 
I would just recommend getting an oversized resistor, like Will has in his video that you can use at some later date for a large inverter. I am looking at a 25 watt 30 ohm resistor to hook up a 3000 watt inverter. That would be the resistor I use for anything under 3000 watts I'm afraid of creating a spark for. 5 Amps is next to nothing for that Heltec Active Balancer.

Kind of a harmless thing though.

We had a capacitor at work for a piece of test equipment. Was about the size of a tall boy, 24 oz beer can, at least that's how I remember it from 30 years ago. When we worked on that, we'd always be told not to short the leads or it could kill you. Don't know if its true or not. I would not use a resistor and my bare hands for that. The Heltec capacitors I would not fear for my life with those capacitors. For the video Will showed with that huge inverter, I would not short a resistor like that without seeing someone else do it. After I know its safe, I'll try it. I've never been much of a blazing new trails kind of person, especially when money or my life would be on the line. Never the first to jump off a bridge.
This where my understanding of electricity gets hazy. By my understanding a resistor is a load and therefore theoretically would not short. However I presume a low value resistor is really not a load at all and this is when a short occurs. I'm sure there is some fancy math to determine when a short is a short. Input appreciated
 
5A Active Balancer can handle up to 300AH Cells
This is the simpler 3s/4s Active Capacitance Model.
So I bought this one today..
6,7,8S 5A 6A for my 200Ah 8S pack. Says 5A 6A, so I'm not sure which it is, but still, sounds like it's plenty sufficient for my pack? I suck at soldering, so I'm hoping that whole process of unsoldering, and re-soldering the appropriate pins for LFP goes smoothly.
 
So I bought this one today..
6,7,8S 5A 6A for my 200Ah 8S pack. Says 5A 6A, so I'm not sure which it is, but still, sounds like it's plenty sufficient for my pack? I suck at soldering, so I'm hoping that whole process of unsoldering, and re-soldering the appropriate pins for LFP goes smoothly.
Yep, I bought that one for my 8S pack. There's just a single place where two pads need a blob of solder between them for LTO, or between two others for LFP. Mine was already set for LFP, which makes sense, as there are way more LFP systems than LTO systems. You should be fine and won't have to do any soldering.
 
Yep, I bought that one for my 8S pack. There's just a single place where two pads need a blob of solder between them for LTO, or between two others for LFP. Mine was already set for LFP, which makes sense, as there are way more LFP systems than LTO systems. You should be fine and won't have to do any soldering.
Good to know. I though I read where it shipped default for LFP so that's good news. Have you considered adding an optional on/off switch? This one has the spot to add that right? Or do you plan to just leave it on 24/7? Also, will this continue to do its thing during the entire SOC? It didn't look like there were any opportunities for setting values.
 
This where my understanding of electricity gets hazy. By my understanding a resistor is a load and therefore theoretically would not short. However I presume a low value resistor is really not a load at all and this is when a short occurs. I'm sure there is some fancy math to determine when a short is a short. Input appreciated
A short is just what we call it when alot and most current rushes through via an alternative unexpected new path. Like a dropped wrench across terminals. It is only dangerous when the flow of current exceeds specifications of the wire/battery/equipment it runs through.

This wrench is both a short and a perfectly fine load to barbecue some hotdogs over if you like. Tecnically speaking.

Just as a river and contrary to popular belief current takes all paths not "the path of least resistance only" but the amount of current through all the different paths is determined by the resistance of said paths.
 
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