Swapping out FLA Golf Cart batteries for LiFePO4 - would like some wiring suggestions

[larry2c]

As I mentioned in a different thread my old GC batteries are tired (6+ years) and I am replacing them with a pair of 165AH LiFePO4 batteries. After weighing my options I have decided to put the batteries in my pass-thru and put a box on the old battery tray that will hold the camping chairs and table that will be displaced.

Back when I installed the solar panels I mounted my solar charger inside the pass-thru so my thought is to use that same bulkhead panel for this upgrade. I'd like some suggestions - maybe with some pictures - of a clean way to route the wiring for all the pieces on the front wall like the CC is mounted so I don't have any penetrations in the front of my TT. I would also like feedback on the way I have the GC batteries, charge controller and battery monitor wired up in regards to if it is "proper" for use with the LiFePO4 batteries. One thing I am not sure of is the shunt for the battery monitor - could it be mounted on a board in the pass-thru or do they actually generate heat and would possibly be a fire risk?

So here's a couple of pictures and diagrams. The CC wiring diagram is how my current system is wired in. FYI - I went with a PWM controller back then to save money but I'm thinking of upgrading it to an MPPT controller now or not far in the future. The battery monitor I have is in a screenshot and I know it's a cheapy but it works fine and the CC and now the batteries themselves have BT monitoring so I'm intending to stick with this monitor. Last is a picture of the "bulkhead" with my charge controller, fuse and solar panel cut off switch.

Any thoughts on what I have along with suggestions for my upgrade would be appreciated!

 

[hamrover]

I am curious what route you went if you have made any headway on this?

I am in the middle of the same upgrade on my G20BHS. I already eliminated the 2 x 80 Ah flooded batteries for 3 x 100 Ah LiFePO4 batteries - placing them in the front passthrough cargo bay. I live in my trailer year round in cold winters of northern Utah - so I didn't want to waste power on heating my batteries via BMS features if I can heat them for free by putting them inside.

Anyway, I toyed with putting a hole in the beautiful front or side of the RV, even considered bulkhead Anderson high Amp connectors - but in the end I drilled a hole through the floor of the cargo bay after carefully locating a spot where I would come out below avoiding any heavy steel members. From there, the cables pass through to the tongue area where they just connect to the old wiring. I still haven't even sealed up my holes properly with foam, yet.

It has been 1 week since the battery upgrade, and after spending all winter with flooded lead batteries in single digit temps (still plenty of solar) I must say that these batteries are GAME CHANGERS in every aspect of the battery game. From predictability to reliability, to ease of data interpretation and planning - I will never go back.

I am still working on a permanent layout board with proper switches, fuses, bus bars and all the fixings attached in one beautiful place. Unfortunately my CC is located much further from the battery setup, so my wiring will look much different in that regard.

My 300A shunt doesn't get too hot that I have noticed - but I will try to keep an eye on it next time I'm taxing it - whether charing or discharging. My plan is to mount the shunt to my plywood with everything else. Presently it is just kind of floating in space....

 

[Aussieguy]

All I did was move the original battery cables from the tongue up through the floor
there was no need to change them as all the loads remained the same

wire length was long enough ... so no splicing was required

I used similar board to mount switches etc.

If you want to add an INVERTER later make your board thicker and bigger OR just mount the inverter to the floor

 

[larry2c]

I am curious what route you went if you have made any headway on this?

I am in the middle of the same upgrade on my G20BHS. I already eliminated the 2 x 80 Ah flooded batteries for 3 x 100 Ah LiFePO4 batteries - placing them in the front passthrough cargo bay. I live in my trailer year round in cold winters of northern Utah - so I didn't want to waste power on heating my batteries via BMS features if I can heat them for free by putting them inside.

Anyway, I toyed with putting a hole in the beautiful front or side of the RV, even considered bulkhead Anderson high Amp connectors - but in the end I drilled a hole through the floor of the cargo bay after carefully locating a spot where I would come out below avoiding any heavy steel members. From there, the cables pass through to the tongue area where they just connect to the old wiring. I still haven't even sealed up my holes properly with foam, yet.

It has been 1 week since the battery upgrade, and after spending all winter with flooded lead batteries in single digit temps (still plenty of solar) I must say that these batteries are GAME CHANGERS in every aspect of the battery game. From predictability to reliability, to ease of data interpretation and planning - I will never go back.

I am still working on a permanent layout board with proper switches, fuses, bus bars and all the fixings attached in one beautiful place. Unfortunately my CC is located much further from the battery setup, so my wiring will look much different in that regard.

My 300A shunt doesn't get too hot that I have noticed - but I will try to keep an eye on it next time I'm taxing it - whether charing or discharging. My plan is to mount the shunt to my plywood with everything else. Presently it is just kind of floating in space....

Just an update - I have finished my installation of the LiFePO4 batteries and I even figured out why my stand alone battery monitor wasn't showing charging (my bad on cable connection). However, the DC House batteries - and I'm sure any mfg's - instructions say to match your CC parameters to the battery mfg's specific parameters. My Renogy PMW controller is pretty old and although it does support LiFePO4 batteries, it does not support actually changing those parameters. The charging voltage is off by about .4 volts so I have decided to upgrade to the Renogy MPPT controller so I can properly match the values. It should be here tomorrow so I hope to re-finish off the install over the weekend.

 

[Aussieguy]

My 300A shunt doesn't get too hot that I have noticed - but I will try to keep an eye on it next time I'm taxing it - whether charing or discharging.

if you are just doing a battery swap without adding a BIG inverter , you system won't see anywhere near 300amps flowing , The existing wiring will work just fine

I turned on everything 12v I could .... at once even running the slides in/out wile doing the same with the awning..... could not measure more than 20amps being used

your batteries will have a combined maximum of 300amps discharge .... BUT you probably don't have the equipment to place such a heavy load on the battery or the shunt

you more than likely have a 55amp converter... that will be the highest amps (charging) the battery will probably ever see

UNLESS you drop in a huge Multiplus 2 or EG4 all in one don't worry if the batteries / shunt never get near 300amps ...
In fact the opposite is more worrying.............. if you see over 60-100amps being used on a simple 12v system , look for blue smoke or really hot wiring

 

[JimM2109S]

To add to Aussie's post above, even a 2000w inverter will not draw anywhere near 300a.

I added a 2000w Renogy inverter to the 3x100Ah battery bank specifically for boondocking, so that we would have the option to run the microwave and also have a 15a receptacle in the kitchen. Both the factory 1000w and this second inverter stay off unless actually needed.

On a whim, I ran a 25' 12gauge extension cord from the 2K inverter's onboard receptacle to the camper's shore power connection using an adapter plug at the shore power receptacle. Turned off the converter, turned on the 15K BTU air conditioner (has a soft start installed) and let the camper cool down. The max draw I observed on the Renogy battery monitor was 140a.

 

[hamrover]

if you are just doing a battery swap without adding a BIG inverter , you system won't see anywhere near 300amps flowing , The existing wiring will work just fine

I turned on everything 12v I could .... at once even running the slides in/out wile doing the same with the awning..... could not measure more than 20amps being used

your batteries will have a combined maximum of 300amps discharge .... BUT you probably don't have the equipment to place such a heavy load on the battery or the shunt

you more than likely have a 55amp converter... that will be the highest amps (charging) the battery will probably ever see

UNLESS you drop in a huge Multiplus 2 or EG4 all in one don't worry if the batteries / shunt never get near 300amps ...
In fact the opposite is more worrying.............. if you see over 60-100amps being used on a simple 12v system , look for blue smoke or really hot wiring

En contraire mon frere... I already installed a 3000W inverter last year, (handles spikes to 6kW) and I'm just now adding the wires to support just that. Like you recently said in another post, go big or go home! haha

I live, work, and play from my RV, and can easily pull 10's of amps from all over the place. Trust me, I didn't guess at any of this. I spent weeks doing math. I have a pretty good idea of the wattage required for pretty much everything on board, and every switch I flip is a known and quantifiable mathematical decision. I am beyond obsessive about it, lol.

My converter is 35A (non lithium), but I have the 40A-AD sitting in a box ready to install, but I'm not worried about that thing. Solar is my game.

Who said I was worried abou the shunt reaching 300A!? I got that one specifically so I shouldn't ever have to worry about it reaching 300A. I just mentioned in response to someone else's question that I would watch the temperature on it out of curiosity.

Anyway, the board and fuses for the backbone of it all are coming along nicely....

 

[hamrover]

Just an update - I have finished my installation of the LiFePO4 batteries and I even figured out why my stand alone battery monitor wasn't showing charging (my bad on cable connection). However, the DC House batteries - and I'm sure any mfg's - instructions say to match your CC parameters to the battery mfg's specific parameters. My Renogy PMW controller is pretty old and although it does support LiFePO4 batteries, it does not support actually changing those parameters. The charging voltage is off by about .4 volts so I have decided to upgrade to the Renogy MPPT controller so I can properly match the values. It should be here tomorrow so I hope to re-finish off the install over the weekend.

Nice work on the new batteries, and welcome to LiFePO4 heaven!

When you say "the charging voltage is off by about 0.4 volts" how far is your controller from your batteries?

On my RV the darn MRF ran between 50' and 60' (round trip) of wire from the charge controller to the actual battery. Even though they used 8 AWG, the voltage drop was between 0.6 and 0.8V. I added a remote voltage monitoring wire direct and separate from the controller to the battery. This allows my MPPT to boost voltage at the source to obtain the expected result at the battery. Some would say move the controller, but I need it where it is for other reasons.... I will later upgrade the 8 AWG wire, probably to 4 AWG.

Which Renogy MPPT controller did you get? I have enjoyed mine these several months.

 

[JimM2109S]

Hamrover, similar situation here on the converter to battery wiring. I ran a separate 2awg wire as I had a fairly easy path to do so. I've now the original 8awg plus the 2awg connecting the two. The -AD converter now properly recognizes that the batteries are Li and it stays in Li mode.

 

[hamrover]

Hamrover, similar situation here on the converter to battery wiring. I ran a separate 2awg wire as I had a fairly easy path to do so. I've now the original 8awg plus the 2awg connecting the two. The -AD converter now properly recognizes that the batteries are Li and it stays in Li mode.

I love it! A man after my own heart. It feels like there are plenty of electrical problems that more copper and $$ can solve, right?
I like the 2 AWG upgrade, bold move, and forward thinking.

It might be a few months before I can motivate myself (and my wallet) to do that wiring job, but it is on the list for sure!

 

[Aussieguy]

my factory copper size was good enough......... for the converter install.
The negative to frame connection was pitiful , my converter is installed into breaker/fuse panel

Cost zero dollars to fix I just traced the negative cables from fuse panel / converter to the frame
it was relying on a star washer to make contact between wire lug and frame

removed the paint and made sure got good metal to metal contact
did the same on the battery end where it connected to frame

since doing it got full 50amp charging from converter to battery... when battery is fairly depleted
once battery voltage gets over 13.8 you will see amps s start to slow down for charging

bad news is ... was a PITA to get at the frame connection for the converter
had to open part of the underbelly .

---------------------------------------------------------------------------------
wiring ... if you looking for some good wiring look at multi strand welding cable
it's not as expensive and works well

can often find it on facebook or yard sales .......... if a person has a busted welder

 

[Aussieguy]

I love it! A man after my own heart. It feels like there are plenty of electrical problems that more copper and $$ can solve, right?
I like the 2 AWG upgrade, bold move, and forward thinking.

It might be a few months before I can motivate myself (and my wallet) to do that wiring job, but it is on the list for sure!

see above forgot to quote it.

 

[hamrover]

wiring ... if you looking for some good wiring look at multi strand welding cable
it's not as expensive and works well

Multi strand welding cable is good.

While looking for deals on wire - do not be fooled. Watch out for the cheaper CCA (copper clad aluminum) which will always look like a good deal $$, but perform worse (higher resistance and poor conductivity) than pure copper for any given AWG size. Cheap CCA stuff is for audio systems, and not critical high amperage power systems.

 

[larry2c]

Nice work on the new batteries, and welcome to LiFePO4 heaven!

When you say "the charging voltage is off by about 0.4 volts" how far is your controller from your batteries?

On my RV the darn MRF ran between 50' and 60' (round trip) of wire from the charge controller to the actual battery. Even though they used 8 AWG, the voltage drop was between 0.6 and 0.8V. I added a remote voltage monitoring wire direct and separate from the controller to the battery. This allows my MPPT to boost voltage at the source to obtain the expected result at the battery. Some would say move the controller, but I need it where it is for other reasons.... I will later upgrade the 8 AWG wire, probably to 4 AWG.

Which Renogy MPPT controller did you get? I have enjoyed mine these several months

My cables from the SCC are only 2' long - everything is on the front wall of my TT and accessed by the pass through.

I got the Rover 30A with a BT-1 bluetooth dongle (which unfortunately doesn't seem to work ) Going to call them tomorrow to see how to figure out if it's the BT-1 or the actual SCC that's the issue.

 

[larry2c]

I have finished the install of my LiFePO4 batteries and the new SCC today and I thought I'd post a couple pics. I don't think my install is as professional looking as hamrover posted but I think it's laid out pretty well and robust enough to hold up in the bouncing box that's our TT.

 

[hamrover]

My cables from the SCC are only 2' long - everything is on the front wall of my TT and accessed by the pass through.

I got the Rover 30A with a BT-1 bluetooth dongle (which unfortunately doesn't seem to work ) Going to call them tomorrow to see how to figure out if it's the BT-1 or the actual SCC that's the issue.

I had the Rover 60 with the Bluetooth module and it appeared to be giving me problems at first as well. I was trying to connect it to a Renogy ONE Core, though.

I remember two things I had to do that helped.
1) first, I had to update the firmware on the ONE Core, which sounds like it does not apply to you
2) The second thing I had to do was remove the battery connection from the charge controller, then connect the Bluetooth module, then reconnect the battery. It was some kind of strange dance like that.

Good luck!

 

[hamrover]

I don't think my install is as professional looking as hamrover posted but I think it's laid out pretty well and robust enough to hold up in the bouncing box that's our TT.

Your install looks solid, and bulletproof for the bouncy roads ahead. That is definitely one aspect of my install that has not been addressed yet, and will be critical before I can move the trailer anywhere.

I made progress on my install as well, but I still need to connect the inverter cables and secure it all.

I have some open lugs on the bus bars to relocate my solar to feed more directly to the batteries as well, but didn't get around to that yet. Baby steps...

 

[larry2c]

I had the Rover 60 with the Bluetooth module and it appeared to be giving me problems at first as well. I was trying to connect it to a Renogy ONE Core, though.

I remember two things I had to do that helped.
1) first, I had to update the firmware on the ONE Core, which sounds like it does not apply to you
2) The second thing I had to do was remove the battery connection from the charge controller, then connect the Bluetooth module, then reconnect the battery. It was some kind of strange dance like that.

Good luck!

Thanks for the suggestion - I'll try the disconnect, reconnect routine! My BT-1 has a Power light on it and that doesn't come on. Was that the same for your issue?

 

[larry2c]

Your install looks solid, and bulletproof for the bouncy roads ahead. That is definitely one aspect of my install that has not been addressed yet, and will be critical before I can move the trailer anywhere.

I made progress on my install as well, but I still need to connect the inverter cables and secure it all.

I have some open lugs on the bus bars to relocate my solar to feed more directly to the batteries as well, but didn't get around to that yet. Baby steps...

The busbars are a great way to go - I just didn't make the leap to that level. I may however add a pair of terminal blocks before I say I'm done...

 

[larry2c]

I think I figured out my Bluetooth issue. When I ordered the Rover 30A from Amazon it offered it stand alone or with the BT-1 dongle. I wanted the BT interface so I ordered the "package deal". After finding it not working I did some digging and here's what I found - I received the Rover 30A G2 SCC which is only compatible with the BT-2 dongle. I initiated a return to Amazon of the BT-1 and ordered a BT-2. Hopefully my attempts to plug in\use the BT-1 haven't damaged the BT interface in the SCC...