LiFePo Battery upgrade completed

[pjshier]

A few posts here and to follow regarding the long lusted-after and recently completed swap from two 6v golf cart batteries in the battery box with stock converter/charger to two 100ah LiFePo 12v batteries, Boondocker Power Center, Orion 12/12 18amp DC/DC isolated charger and Victron 712 monitor with temp.

A photo of the battery box, but you have all seen one before. Labeled wires and some chunks of an old mud flap for cushion and separation. Then the battery disconnect switch which was reused, then the typical rats nest.

[pjshier]

I decided to put the Orion on the "rear" wall of the rat haven; once i had the Orion in hand, I noticed the wire terminals had a square cross section - a good excuse to acquire a new tool. The set of various size wire connectors and the "square" crimper made quick and satisfying work of the process. I installed wires in the Orion before I mounted the unit to the carpeted wall.

You can see the 712 shunt mounted and the separating bulkhead is removed. The batteries are sitting on some high density foam about 1 inch thick to insulate from the cold floor and to provide some cushion - I recycled the foam from some airplane seats I had recovered years ago. The batteries are kept by a 2-by fence attached to the floor and strapped in place over the top.

[pjshier]

I moved the inverter from the front wall of the rat haven where it was inaccessible and hanging on the aluminum skin by two screws to the front of the curb side twin bed storage locker. Now the fuse and manual switch are accessible, and it doesn't take up much room. I also stashed the 712 here for now, and use bluetooth to monitor.

Relocated the stock Zamp solar and tongue jack to the bus bars and resealed the hole in the floor where the battery and inverter cables used to pass into the rat haven. Seriously, folks - it looked like they locked a person in the trailer with 100# of wire, crimpers and a case of whiskey.

With the carpeted bulkhead back in place, and the front "fence" painted black, it should work well and safely, and doesn't look like a total rube project. I have tape over the battery terminals just to preclude any shorts from inadvertent flying metal if we hit a frost heave at speed, but don't plan to store such things there.

Next test is the Orion but am performing spring maintenance on the hitch and will wait for an actual road test, i think. Let me know if a static test with the truck simply parked and running - after engaging the brake in tow/haul - will work.

Here's hoping nothing bursts into flame tonight.

[pjshier]

In the end, I reused a lot of cable and components I already had. The only replaced item was the inverter fuse for a 100A breaker mounted in the front compartment.

While I was tempted to upgrade the inverter, we don't use it that much and the Nespresso mini doesn't tax it. The Boondocker power station was installed two years ago in anticipation of LiFePo, and easily switched to steady 14.4v charging.

Nothing "budget" about the batteries, but snagged them on a local sale.

[jeffmc306]

pjshier, very nice job! Thanks for documenting and sharing your work. We all learn something from posts like yours.

Bravo!

[BT2513]

Can you explain more about the role of the Orion? It looks like you want to use your TV alternator to charge the batteries. What was the wiring scheme?

Looks great! I'm considering something similar to recharge the batteries with my TV.

[Mark of SJC]

Very nicely documented!

Now that some lithium batteries have the option of internal heaters built into them, is there an option to keep them located in the existing battery box? I think I heard they were taller than standard batteries, but there was an AS vendor that offered an "extension kit" to accommodate the additional height.

In our FB27, we only have one storage locker - I hate giving up space in it, if I can avoid it!

[pjshier]

From research here and elsewhere, I was sufficiently convinced to manage and/or isolate the flow of electrons from the TV batteries to the thirsty TT LiFePo batteries.

Management involves the Orion limiting the flow to 18 amps - if that is even achievable over the 10 gauge wire from the TV through the pigtail to the Airstream distribution block - as well as convincing the new battery BMS that it should take what it can from the TV, as presented by the Orion.

There was a lot of discussion about the modern TV charging systems and smart alternators and etc. not really presenting a satisfying flow of juice to the BMS due to relatively small wires and resulting low capacity/high resistance.

The other concerns reported involved the draining of TV batteries to feed the LiFePo TT batteries when parked and the 7 way pigtail remained connected. Some reported the TV circuitry prevented this, others suggested unplugging.

The Orion also "talks" via bluetooth. This season I will monitor what's going on and use that data to decide if adding larger gauge wires and an Andersen connector to the TV and TT makes sense, as some have recommended.

I wired the Orion with the largest gauge multistrand conductor that was practical given the receptacle and connector size, understanding that larger gauge and multistrand (lots of strands) are considered optimal for reducing resistance and line loss for 12v systems.

I took a semester long class on solar systems to help me support a couple of remote building 12v systems and have been acquiring some sense of what it takes to make things happy, but am by no means an expert.

[bcheever]

Really appreciate all of the detail you put into this post! Planning a similar job here, and this will be invaluable.

[pjshier]

Couldn't wait so taxied the truck over to the AS and connected the 7 way pigtail to the truck. Before I launched the Victron Connect software on my iPhone, I put it in tow/haul mode and tapped the brake. Instantly saw the Orion show up in the Devices menu of the software. A couple of updates to the Orion loaded through the phone. mid way through one update, i got out of the running truck and closed the door behind me - and the update stalled. Did the truck shut off the charge line to the trailer connector? Seems like. Got back in and pushed on the brake and it started again. Can't say for sure if pressing the brake was necessary.

The 712 is reporting over 12 amps of charge and 160 watts; the Orion is reporting 13.1v from the truck and is pushing 13.6 to the batteries. All this at idle.

I suspect there is more I need to do in order to optimize the settings, and further understand what the instrumentation is really saying... time will tell. So far, so good.

[BT2513]

Originally Posted by pjshier

The Orion also "talks" via bluetooth. This season I will monitor what's going on and use that data to decide if adding larger gauge wires and an Andersen connector to the TV and TT makes sense, as some have recommended.

I am transplanting a BMV712 and SmartSolar charger from our old camper to our new AS and was also considering this. However, my plan was to mount an Orion directly in the unused aux battery tray of my Tahoe and run an Anderson connector to it. I have a 10AWG portable solar extension cable that I can run from the TV to the Zamp connector on the AS (probably replace it with an Anderson as well). My Tahoe has the stock 160 amp alternator - not sure how much power I can draw at idle but it seemed like a great emergency-use-case setup to have if the solar panels aren't cutting it.

[pjshier]

if you are content to use the 10 AWG - I think that is the stock size used in the 7-way pigtail that delivers battery charging to the TT. You many not need an Anderson connector. But to take advantage of the Orion isolation feature you would need to find the TV wire that supplies battery charging to the 7-way cluster and make the Orion the power source for that wire.

[pjshier]

Batteries finally got down to 85%, so i plugged the AS into the 30 amp house AC power receptacle. The Boondocker converter/charger kicked on after a minute and has been pushing 30 amps or so into the batteries. No hot or even warm wires. Happy camper.

[BT2513]

Originally Posted by pjshier

if you are content to use the 10 AWG - I think that is the stock size used in the 7-way pigtail that delivers battery charging to the TT. You many not need an Anderson connector. But to take advantage of the Orion isolation feature you would need to find the TV wire that supplies battery charging to the 7-way cluster and make the Orion the power source for that wire.

I'm almost 100% sure its significantly smaller gauge - at least in my Chevy Tahoe. There are 2 wires that have to be connected in (older?) GM vehicles for the braking and battery charging to take place and they are nowhere close to 10 AWG. Maybe I'm missing something though...

I would prefer it to work via the pigtail but I also like the straight ahead idea of having just a separate connector where I know where all the components are in-between the TV battery/alternator and the camper battery.

[uncle_bob]

Originally Posted by BT2513

I'm almost 100% sure its significantly smaller gauge - at least in my Chevy Tahoe. There are 2 wires that have to be connected in (older?) GM vehicles for the braking and battery charging to take place and they are nowhere close to 10 AWG. Maybe I'm missing something though...

I would prefer it to work via the pigtail but I also like the straight ahead idea of having just a separate connector where I know where all the components are in-between the TV battery/alternator and the camper battery.

Hi

On the typical modern Ford F-250, the wires are indeed 10 gauge. They are rated ( = fused) to supply 30A. Indeed, getting 30A at the end of those wires (plus the wiring into the trailer) is unlikely at any reasonable voltage.

Bob