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That has all the look of a poor connection (discolored bolt). It heated under load, melted some plastic and got worse. How tight is that nut on the fuse?

Two 206Ah batteries in parallel gives you 412Ah capacity. Where does your 824 number come from?

Your meter is set for AC volts!

Save your fuse. Put a 12V load in series with your inverter connection (basically in place of the fuse). If the inverter is shorted the 12V load will have full power and operate just like it was tied to the battery. While this is pulling some current you can measure the voltage drop across the...

In the top loop there are 2 14V batteries. Voltage readings around the loop add up to zero Kirchoff's law). In the lower loop the left battery has shut down and now instead of being a current source it becomes a load. Again the sum of the voltages in the loop will be zero. This explains the...

Short answer: NO. Here's why. As noted a BMS can't monitor individual cells if you parallel them, and you will be limited by the BMS current rating (200A in your case). Best bet (staying with 12V) would be to build 4 batteries, each with their own BMS. You will be able to monitor each of your...

After a recent purchase of a pile of parts from a fellow DIY'r I started the battery building process. The 8 Ganfeng 277Ah cells were grouped into two sets of 4. I did an initial 4S set with me as the BMS charging at 14.2V (caution if you are a BMS, pay attention). When the pack approached a...

Here's my cell. The charge/drain setup. The jumpers are long enough to make diagonal jumps so I could make a 4P out of a 4S without moving cells. In this case I have one 4P charging and one 4P with a headlight load on it. My jury rig wire job to discharge during the last trailer trip. Threw...

If they were top balanced before and got that far out of balance from sitting around for a month, I'd say you have some cell capacity issues. Mine have been sitting for month and the cells are within 0.006V delta.

In this case the wires don't need to be exact. In fact, if you have an array that is 20 feet wide, you can connect the positive at the nearside and the negative at the far side (20 feet further). The voltage drop is a function of both wire lengths so the shorter the better. The equal length wire...

I don't like voltage readings when it comes to battery SOC. Even their chart has three different SOC numbers for the same voltage. You have 400Ah capacity in parallel. That means it will take 100 hours for the 4A charger to get them charged. Your solar, with good sun, will be two days. If they...

After 18 months on the job, one of the batteries was getting a bit of drift and I would see 240mV cell difference at the top. Either passive balancing didn't work or I never kept it at the top long enough but the simple fix is to give it another top balance. Broke it down and built a 4P. Watched...

The battery capacity is a programmed value in the settings, you can change it to 302.

If you draw a couple of batteries in series, add a load resister and measure the voltages is makes sense. Now mentally replace a battery with a high resistance (BMS open) and the voltage measured on the terminals of the open battery will be equal to voltage of the good battery but the polarity...

It was an $80 coupon on Amazon when I bought mine ($219). Gave it some non scientific tests for capacity and was pleased to get 100Ah out of it for a couple of cycles. Charged to full at 25A with my AIMS and discharged with a 200W heater on my 600W Samlex inverter (about 18A DC).

When things are working, each BMS sees its own voltage. In a series circuit (4 batteries and a load), each battery shows 12V and the load sees 48V. Now if you put a switch into the circuit and open it, then the load will see 0V. You can measure 48V across the switch. Same is true for a BMS that...

You want the battery negatives tied together. That way your shunt will show both (but will need the new capacity number programmed in). Anderson is a good way to go. You should have a fuse on the 120Ah battery positive to protect that wiring. Be cautious making the Anderson connection, batteries...

Are those cells stacked? It looks like 2P8S in the photo which is only 24V. Is there a second layer of cells?

You may need to get the battery charged up a little before the MPPT can start doing its thing.

When you measured -10V on the battery it was because that battery was shut down. The two batteries and the load form a series circuit. Replace the battery with a resistor about double the resistance of the inverter and you will get those same measurements. A BMS has some resistance when shut...

As noted there will be a lot of wires jumping over the studs. I would eliminate the nuts on your battery terminals so that the two crimps are making direct contact with each other rather than running through a nut.

In position 1 the RCBO will get power from the mains when contact pairs 1-2 and 5-6 are closed. In position 2 the RCBO will get power from the inverter when contact pairs 3-4 and 7-8 are closed (then run through the 2-4 and 6-8 wire jumpers). In the off position, your mains power is sitting on 1...

The BMS on your second battery thinks it is 640Ah. That is a programable setting in the BMS and should probably be 400Ah. I use the Overkill app and at the bottom of the home screen is a tab to get to the settings screen. All sorts of numbers to review, with the capacity wrong, I'd check the...

Keep in mind that a 50A RV service has two 50A legs (total 100A) plugging into a 30A service will give you less than one third the power.

Comment about wire length. The positive and negative cables don't need to be the same length as each other, but rather, all positives to the battery should match and all negatives should match. The positives can be 12" and the negatives can be 36" no problem. I like the separation of the bars to...

The goal is to keep all the exposed metal parts at the same potential. It's a mute point if you mount the inverter to the frame (metal to metal contact) but there is a chance of a poor electrical connection, hence the 14 AWG wire. This wire does not carry any current so size isn't too much of an...

The upper ring is series, the lower ring is series. The two rings are in parallel. As noted, your 95V is correct for the 3 in series.

Looks like the 100A fuse is between two cells. I would think that the added resistance would throw off the cell balance.

You can't get 12V from an 8s BMS. Best bet is to make another 4s battery with BMS and parallel it into the RV.

If this change is only to add capacity there is no need to mess with the wiring. I'd do the jumpers for 100A just for consistency and after they are in parallel, move the system positive or negative to the new battery to give you a diagonal connection to evenly split the charging and load currents.