LifePO4 Install

[dkovacevic]

Hello,

Posting this for advise or suggestions.

Attempting to add a lifepo4 battery, inverter, and charger to a Cruiser RV Fun Finder. The battery will provide an additional 200Ah (or 2400Wh). The battery and inverter have been tested running a mini fridge; power consumption of the fridge averaged less than 80W while running.

Might install a switch to allow for use of the existing deep cycle battery / converter system as backup.

Planning to install the battery underneath the fusebox / converter combo. Space is tight in the compartment, but should accommodate the additional equipment.

There is space in the fusebox for another fuse; intend to install a 15A fuse and connect to 120V inverter input (inverter has a transfer switch, and allows shore power 120V pass-through).

It appears that all of the 120V electrical outlets in the RV are on the same breaker; intend to disconnect that line from this breaker, and connect it to the output of the inverter. (Looks like the converter shares the breaker connection with the outlets; intend to separate the converter and put on its own breaker).

[dkovacevic]

A big thank you to Steve Gable of Headway Battery USA. Good product, and he helped me put together and plan a lot of the overall system.

[dkovacevic]

Battery is now in place.

[dkovacevic]

Originally planned to install inverter as close to the battery as possible. Given how tight this compartment is (heat), and the vicinity of water hoses, it might end up being installed in the open cubby above this compartment.

Disadvantage to moving the inverter further away is loss of power over longer distance cable, loss of storage space, and less ideal weight distribution (both higher up and further from middle of RV).

If kept in the compartment, would probably need to install a vertical wood panel to separate the left side 'electrical' compartment from the right side 'water'. (Might be a good idea to install this separator regardless of whether the inverter is installed here).

The wiring / plumbing combination in this compartment is a bit of a nest; cleaning it up would probably help.

[HarryStone]

As far as losing power on a cable run, use bigger cable. There are charts available that will tell you what loss to expect over a set distance, but you probably knew that.

[dkovacevic]

Thanks Harry.

The compartment is a bit cleaner now. The inverter fits more easily.

Also somewhat relevant: the BMS installed on the battery supports up to 60A output, which means a max output of ~720W. Lower max load means less heat at the inverter (large margin- 1200W, with 2400W peak).

UPDATED: Mistaken. The BMS supports max 60A charging current; max 100A output, which does theoretically reach the max output of the inverter.

Leaning towards installing inverter in the cabinet.

[dkovacevic]

A power monitoring system, including a shunt is planned to be installed.

The BMV 700 draws about 4mA while connected; it would be nice to wire a switch in series with the fuse to allow for easy disconnect when putting the unit in storage, but the switch might impact the accuracy of the monitor readings (additional resistance).

Not sure how to proceed on that. Might wire the switch to the BMS to disconnect the circuit there rather than at the monitor.

[dkovacevic]

Mostly completed install in the compartment.

Left the old converter installed; detached from the 12v coach circuits. Also disconnected the 12v deep cycle battery from the 12v circuits; attached it directly to the old converter (added a couple fuses between them, to protect against reverse battery install). Decided to keep these for a few reasons: having a backup power system might be nice; the trailer winch motor might not work as well drawing power through the long cable to the lifepo4 battery.

The charger is not grounded - that's next. Otherwise, the system works.

[1361]

You're more brave than I. I would be a bit intimidated to get into the "rats nest" of wiring. Good job for just taking on the job.

[dkovacevic]

I received a lot of help from Headway Batteries USA in terms of learning how all of the new stuff worked. Hooked it all up in testing first.

The wiring nest was a bit easier to deal with once the loose wires were more organized. That was tedious; disconnected many of the 12v lines one at a time from the fusebox, rerouted them, and then reattached at the fusebox. Grandfather gave me a bunch of organization type tools- zip ties, conduit tubing and the like.

The most difficult aspect of this job was the small space. Didn't seem like that big a deal, but the reality is that most of the components needed to be tilted / rotated into place, and there isn't much space. Will need to install a vent for the charger, too- just leaving the compartment open for now.

[dkovacevic]

Plastic clamps used in the AC side of the fusebox were frustrating. Removed and replaced with metal twist types.

Apparently one of the most common ways RV fires occur is electric problems on the 12v side of things. Good to keep in mind if attempting something like this.