Teej's Honda Element Tiny RV

[tjoiner1986]

After this build, I totally get why a lot of people steer clear of 12-volt systems. Working with this 1/0 cable is a PAIN. It doesn't flex much so I'm limited in terms of component placement. After working on this the last two nights, this is the best solution I've got. Yes, I could put foam on top of the battery or something and put the BMS on top of that but I want everything to be easily accessible. Without having to remove something else.

I plan on organizing these cables a little better with the aid of zip ties, particularly the little wires to/from the shunt, USB port, and inverter.

 

[MisterSandals]

Your BMS and shunt should not both be connected directly to the battery.

Should be:
battery(-) <-> BMS <-> shunt <-> loads/charger

 

[tjoiner1986]

Your BMS and shunt should not both be connected directly to the battery.

Should be:
battery(-) <-> BMS <-> shunt <-> loads/charger

Ah, so as far as the BMS is concerned the shunt is a load. Makes sense. Thanks!

 

[MisterSandals]

so as far as the BMS is concerned the shunt is a load.

If the BMS cuts off, then your negative bus bar still has power thru the shunt. You are essentially bypassing your BMS.

 

[meetyg]

Ah, so as far as the BMS is concerned the shunt is a load. Makes sense. Thanks!

The BMS is "part of the battery". I know that some prefer the shunt and then the BMS, but I like to consider the BMS part of the battery.

In any case, they should be in series with one another, not in parallel.

One more thing: I can't tell from the picture if you have any compression on those cells.
You should have some sort of compression, or at least fix them together somehow, in order to minimize stress on the cell terminals when the cells will bloat a little. These types of cells can expand and contract, during use.

 

[tjoiner1986]

Yeah, I had a brain fart and later thought "duh, the BMS is part of the battery."

I rewired everything, zip tied here and there, and mounted the Bluetooth module to the cover that goes over the negative bus bar. I don't really like the placement of the BMS but with these stiff 1/0 cables, it's the simplest/easiest place to put it (except for on top of the battery which I don't want to do).

The mobile app for the BMS connects and I can toggle battery charging/discharging. Other than that, I haven't dug very deep into the app. The Victron app for the shunt also works.

All of the nuts are tightened down. At this point, all that's really left to do is move it back into the Element, connect the solar panels to the charge controller, close the breakers, and fire this up. Part of me is very eager since it's going on nearly 9 months since I ordered the LiFePo cells. At the same time, I'm super nervous that sparks are going to start shooting. It's almost night here anyway so I won't really accomplish much by connecting the box to the panels today.

As for compression, I've got the pack "mummy wrapped" in a generous amount of Kapton tape.

If anyone is curious about what's what or what's going where, let me know.

 

[meetyg]

Yeah, I had a brain fart and later thought "duh, the BMS is part of the battery."

I rewired everything, zip tied here and there, and mounted the Bluetooth module to the cover that goes over the negative bus bar. I don't really like the placement of the BMS but with these stiff 1/0 cables, it's the simplest/easiest place to put it (except for on top of the battery which I don't want to do).

The mobile app for the BMS connects and I can toggle battery charging/discharging. Other than that, I haven't dug very deep into the app. The Victron app for the shunt also works.

All of the nuts are tightened down. At this point, all that's really left to do is move it back into the Element, connect the solar panels to the charge controller, close the breakers, and fire this up. Part of me is very eager since it's going on nearly 9 months since I ordered the LiFePo cells. At the same time, I'm super nervous that sparks are going to start shooting. It's almost night here anyway so I won't really accomplish much by connecting the box to the panels today.

As for compression, I've got the pack "mummy wrapped" in a generous amount of Kapton tape.

If anyone is curious about what's what or what's going where, let me know.

View attachment 94632

Nice!

 

[tjoiner1986]

Well, the panels are connected and I reset all the breakers. Power is flowing. I need to read up on this JBD app, though, because I'm not entirely sure what all of it means.

 

[tjoiner1986]

Discovered an issue. Two actually.

1) The fridge isn't powering on. There 14.06V throughout the system, including the power cable entering the fridge. There's a dedicated fuse before the cable at the fuse box and one after the cable in the fridge. EDIT: All fuses are good.

2) Charge controller doesn't seem to be charging. PV in measures 16.30V at 7:30 PM. That's measured where the cables enter the charge controller. The app, however, is telling me not enough voltage. Oh wait. App tells me it doesn't charge unless the it's 5V over the battery voltage. That's weird to me.

I'll check again in the morning.

In other news, the USB port charges my phone and the inverter powers on but I haven't tested it yet. I want to know the battery is charging like it should before I start drawing serious power from it.

 

[tjoiner1986]

The fridge has dual power options -- 12/24V via car power socket or 120V via standard power cord and wall outlet. To rule out possibilities, I plugged the fridge into the 12V socket where my phone charger usually is: NO POWER. Next, I plugged the phone charger into the 12V socket built into the battery box: POWER. So I know the socket works. Lastly, I connected the fridge to the inverter: POWER. With that, I know the inverter works and the fridge's 120V input works. The issue seems to be the fridge's 12V input. I'll be calling Iceco's customer support this week.

As for the battery/BMS/charge controller, I still feel like something isn't right. The charge controller is on "float" and the app shows it's outputting 1 watt. I suppose the battery -- which I have not used since top balancing a couple months ago -- could be fully charged. Perhaps everything is normal after all.