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So according to that, the problem is when there is warm humid air outside, and the inside temp is air-conditioned below the dew point. Is it ever humid in Las Vegas?

I'm working on a DIY BMS using a Teensy 3.2 to talk to the board that's built into the battery module and control a relay to disconnect/reconnect the battery. This is dirt cheap. It can also instruct the board to balance at whatever SoC I choose. I'm basing it on the code from here...

I have the teensy talking to the battery module and logging the cell voltages and temperature. It should be a simple matter to connect and control a relay, which is the next step. After that, I will have it control the charger and the inverter. It’s all pretty straightforward. I just need to...

Here's an interesting article on hot switching relays: https://www.pickeringtest.com/en-us/kb/hardware-topics/switching-system-specifications/hot-switching-relays Of particular note is this: An inverter has a large capacitance (which is why you aren't supposed to attach it to a Victron...

This is an excellent point. If the primary low voltage protection is in the inverter, I have no concerns about the relay failing closed. Unfortunately, the inverter that I want to use for my project has fixed low voltage cutoff that is too low, so I need to figure out a switching solution that I...

Replying to myself, here, in case anyone comes across this post with the same question. So the way this works is: 1) You need to set a reasonable amp-hour value for OAH. This is is used the the percent calculation. You can dial in a more exact value later. 2) Either charge the battery to what...

@Justin Laureltec The BP-100 and BP-220 both have a peak current rating of 600A. As long as the inrush current draw of the inverter is below that, shouldn't it be fine?

To determine which side is positive and which is negative, you can just use a multimeter in voltage mode. If you connect it backwards, it will show a negative voltage. Another way is to try to decipher my ASCII art! When viewed from the top: +--------+ | | | | | | |...

BTW, can you post a photo of the potentially damaged BMS wires?

Will, what's your BMS idea? Have you seen this: https://github.com/collin80/TeslaBMS The Model S modules have a built in BMS. You just have to talk to it over serial at a weird baud rate to make it work. I think it should work with a $20 Teensy pretty easily, which is my plan. (Not everything...

Not yet. Once it's a complete BMS, I might do that, but right now, it's more like a proof of concept. And really all I've done is taken the original code (linked in my previous message) and made a few hacks to it.

If the inverter does not have a programmable low voltage cut off (and the fixed cutoff is too low!), is there any reason an external cutoff (such as a Victron BatteryProtect) wouldn't be just as good?

Kudos on the new forum! I think it's a big improvement! I think XenForo automatically scales inline images for the viewer's browser size (or at least, I've seen this on other XenForo forums), so I'm not sure "taking up the entire post" should be much of a concern. This was for sure a problem on...

In the Q/A on that page, I see a couple of answers that say the clamp measures AC only. And in the feature list, is says this: But then the photo implies the clamp does measure DC current, because the AC and DC current appear to share the same position on the dial, as well as the positive lead...

Something you didn't address from that article, though, is the statement that relays are typically rated for resistive loads, and that such ratings do not apply to capacitive loads. Current is current, of course. But is there more to it than that, which I don't understand? The article implies to...

What about using a thermistor-based current limiter? These initially provide resistance to limit current, but as they heat up, the resistance drops to practically nothing. The disadvantage is they need cool-down time between sessions.

The largest I see in a cursory Digikey search is 80A for $32. But you could put smaller ones in parallel. For instance, you could use six 36A current limiters in parallel for a total of 216A and a cost of $15: https://www.digikey.com/product-detail/en/ametherm/SL32-0R536/570-1057-ND/749897

Yeah, that's true. 78W is a decent amount of power. What's the Victron's on resistance?

I would think so. It’s just like using two multimeters simultaneously to measure the voltage drop across the shunt.

Yeah, that was my thought. It has certainly felt dry every time I have visited. But I'm acclimated to coastal San Diego. I know that Las Vegas can get quite cold (again, by my San Diego standards) in the winter, and that's where a good barrier might be important, but more to keep the cold dry...

85 kWh is the pack, which is made up of 16 modules, each 5.3 kWh. The nominal voltage of the module is around 22 V (+ or - depending on charge state), which is nice and safe (no electrocution risk, but there's still a fire risk). These are wired up in series in the pack, making for about 350...

The old forum still exists, if you want to access any of the original content. See here: https://diysolarforum.com/index.php?threads/finally-we-have-an-amazing-forum-on-our-own-server-click-here-for-migration-instructions.1/

No HOA, I hope! I'm pretty sure I wouldn't be allowed to attach to the wall like that, at my house.

I have meter #2 above. I've had it a while, and it's showing current and voltage correctly. But it always shows the battery SOC as 100%. How do I get this to work? Any hints?

I was watching @Will Prowse's latest video (), and I wanted to start a discussion on it here. (I can't stand YouTube's comment system.) My concern is that relying exclusively on the relay to protect the battery from over-discharge might not be a great idea. When a relay fails, it usually fails...

Doesn't the 24V MPP all-in-one system that @Will Prowse has talked about in his videos have configurable voltages that would make it compatible with a 6S Tesla module? If so, it would be awesome if Will could revisit his Tesla module in a video!

I haven't yet found a spec sheet for the NVX relay in the video. Even a high quality relay will can fail, so the question that needs to be considered is, what are the chances? Is the risk of damage to an expensive battery small enough to take? I genuinely don't know the answers.

I can't find the user manual for that one, here's the user manual for the PIP-HSP/MSP: http://www.mppsolar.com/manual/PIP-HSP,MSP%2024V/PIP-HSP_MSP%2024V%20manual.pdf Starting on page 17, it gives these voltage ranges: Bulk charging (CV): 24.0-29.2V Float charging: 24.0-29.2V Low voltage...

The clamp on those handheld multimeters is a usually a current transformer, which only works for AC. For contactless DC current measurement, you need one with a hall effect sensor, but those don't seem to be very common in the handheld multimeter form. There are a bunch of panel mount versions...

I find Hawaii to be an interesting example, as everyone says electricity there is super expensive. But from what I can tell, Hawaii's rates are actually cheaper than San Diego! It doesn't make any sense.