2015 Vista 27N - Upgrade to LiFe04 Batteries

[powercat_ras]

Thought I'd share my project to upgrade to LiFe04 coach batteries.

I have a 960 Watt Solar system that can output up to 60 amps to the batteries in perfect conditions, a 3000 W PSW Inverter feeding entire coach thru a 30A transfer switch (converter charger is locked out when on inverter power), 4 2018 vintage 6V 200 AH golf cart batteries, Victron Battery Monitor w 500 A shunt.

Sharing because many don't realize that not just batteries get changed when you go to LiFe04 on a motorized RV, and because I figured out a way to avoid replacing the Precision Circuits Battery Isolator that Winnebago used on mine and a lot of other RVs.

When going to LiFe04 batteries:

You have to protect the alternator which involves preventing the chassis battery system from connecting to the coach battery system when ignition switch is in run. You add a ignition run enabled DC-DC charger that limits the alternator load and battery charge current to safe levels when RV is running. You change the Shore / Generator Powered converter-charger to one that is compatible with LiFe04 batteries. If you have a Battery Monitor and/or solar they need to be re-programmed to update the battery type and battery capacity.

I am doubling my usable storage so I can run a small portable air conditioner in my RV longer than I currently can now on just the GC batteries. Otherwise 2 Li batteries would be enough to replace 4 GC batteries.

My upgrade parts list:

4 100 AH Lithium batteries $ 1210 Replaces 4 GC Batteries
4 Group 27 battery boxes $ 64
Powermax PM4 Converter Charger $ 148 Replaces non-compatible unit
Renogy 40A DC-DC Charger $ 172
2 60A ANL Fuses w holders $ 18
Wire and supplies $ 40

Total without labor (includes KS sales tax) $ 1,652

Time to upgrade: 12 hours


1. Using 4 Lisuateli 12V 100 AH LiFe04 Batteries. Others had bench tested with good results so I took the risk of this supplier which was very attractive for price and features. I bench tested the ones I received and all were full 100 AH capacity and met proper voltage curves. I chose because it is very unusual for it's price point ( $ 278 ea. w shipping included ) to have an internal Battery Management System (BMS) that includes temperature protection to prevent battery from taking full charging current at very low temperatures - this can damage it. This manufacturer recommends use of up to a 20 amp per battery charge current and 14.4 to 14.6 volt charging voltage to maximize the battery life, so I designed my system accordingly.

I found Group 27 Battery Cases were a perfect fit for these batteries, to protect them.

2. As part of changing to LiFe04 I had to prevent the Coach - Chassis Battery Isolator Contactor from closing when the RV was running or I would have quickly driven my alternator to failure .

I figured out how to make a modification to the Precision Circuits Battery Isolation Manager (BIRD) so I would not have to replace it. The Generator Run input on the BIRD inhibits the Isolator Contactor from operating when the Ignition in Run input is also present. So I used a dual diode of same type used to double feed towed car tailamps to feed both Generator Run and Ignition in Run signals to the Generator Run input on the BIRD. Whenever Ignition in Run has signal the BIRD Isolator is now inhibited. With Ignition NOT in Run everything works same as before, the BIRD can continue to do its thing and keep the chassis battery charged if the BIRD senses it needs it.

3. I installed the Renogy 12V 40 Amp output DC to DC on-board battery charger to charge the coach batteries when driving. Renogy recommended the 40 Amp output model for the type of alternator in the Ford F53. Picked up chassis battery + and the ignition run signal at the BIRD. The DC to DC also has the advantage of taking whatever voltage the alternator is putting out and only putting out 14.6 volts which allows the LiFe04 batteries to fully charge to 100% from charging while driving.

4. Replaced my 100 A Converter Charger that was not designed for LiFe04 batteries with a 60 Amp PowerMax PM4, it is set-able and mine is set to charge LiFe04s.

5. Re-programmed my Solar Charge Controller for LiFe04.

6. Re-programmed my Victron Battery Monitoring System to LiFe04.

[steved28]

Thanks for the great info. I am in a similar situation but luckily my Magnum charger-invertor had an upgrade available to the remote head to support LifePO4 batteries. I am curious as to why, or if, you could just disconnect the output of the BIRD to the coach batteries altogether? Then just add the DC-DC converter? Also, do you have a generator on board? Do you know if the generator draws it's starter from the chassis, or coach, batteries?

Thanks,

Steve

[powercat_ras]

On the 2015 Vista 27N, the leveling system is fed from the chassis side of the BIRD. The Onan generator starter is fed from the coach side of the BIRD.

One interesting fact is that the Onan 4000 generator specs say the generator starter worst case can try to use up to 450 Cold Cranking Amps (CCA) at 0 degrees F. I wondered why Winnebago had it fed with a 300 amp DC fuse guess that is why. I'm OK post LiFe04 conversion since I have 4 LiFe04s, each internal BIM current limited to 100 A, in parallel but for other installs with less max amps LiFe04 capacity it likely means that the generator feed may need to be shifted to the chassis electrical system to reliably start the RV generator at cold temperatures. This is one reason I went with 4 LiFe04s in parallel vs the 200 or 300 AH LiFe04s. I had noticed that the bigger capacity batteries typically were also limited to 100 amp maximum DC output internally.

The leveling system hydraulic pump also has a huge worst case DC current draw (Winnebago used a 200 Amp fuse on it) but that's not an issue on my RV since it is chassis fed and the Lippert manual says coach engine should always be running when leveling.

There were multiple reasons I did not want to re-work with the BIRD and the BIM module that controls it other than the mod that inhibits the BIRD from connecting when the Ignition Switch is in ON position.

1. The BIRD, BIM, Coach Isolation Relay, and Chassis Isolation Relay are an integrated assembly that includes the ANL fuses for the generator and leveling system. I wanted to minimize changes.

2. The BIM control module has great bi-directional logic for when it operates the BIRD, and I wanted to have it continue to intelligently connect Coach to Chassis when it sensed the Chassis battery needed to be charged. It saves having to add a trickle charger to the RV to keep the Coach battery charged.

3. The BIM control module has a dash "boost" switch input and I wanted to have it continue to be an option to use the dash switch to connect the Coach to Chassis manually to aid in starting if the chassis battery had trouble cranking the engine, and I had good coach batteries.

[steved28]

Excellent explanation. Thanks again. I also will be running 4 100Ah batteries, and have just ordered the DC-DC converter you recommended. Sorry to say (for you) that it is actually on a black friday sale right now and might be cheaper than you had paid. Now I just need to locate the BIM, as I never had any reason to find it before. I have used the relays you chose in my Jeep toad. I have all Winter to get it right. So I reserve the right to pick your brain again

Best regards

[powercat_ras]

Assuming you have both a Coach Battery Disconnect and Chassis Battery Disconnect switch by the entry door then it will be the same as my 27N. The integrated assembly that has the two two disconnect relays and the chassis-coach connect relay in the middle is located in the Chassis Electrical Box behind the circuit breaker panel.

The Chassis side large cable connected to the BIM are marked with red tape, I connected a 4 gauge wire to there to power the DC-DC converter. I also picked up the IGN on signal from the BIM control module and conected it to the DC-DC enable input with a 14 gauge wire. I connected the negative terminals of the DC-DC together with 4 gauge and ran a 4 gauge from there to the frame rail to handle the current difference between the negative in terminal and the negative out terminal, which the DC-DC charger manual says can be 20 amps worst case. The actual current difference is actually much less than that. I used 60 amp ANL fuses in the in and out DC + lines as Renogy recommended.

When I tested the completed upgrade, I saw a maximum ouput of the Renogy DC-DC charger to be 43 amps. This was with coach idling, even at idle the alternator will drive the DC-DC to full output. I set it to output 14.6 volts max so that the batteries would see at least 14.4 after battery cabling voltage drop when doing the final LiFe04 topping off charge. I saw the DC-DC output voltage to be much less than 14.6 until the very end of battery recharge since the DC charge output is current limited to aprox. 40 amps. Same true when charging with solar or the converter charger.

The 4 Lisuateli 12V 100 AH LiFe04 batteries in parallel I used would absorb the full 10 Amp each all the way to 14.4 volts where charge current would taper down slightly and then the internal Battery Managemet System would cut the current in to the battery to zero.

You can get a drawing of the Chassis Electrical Box from the Winnebago web site. The last year Winnebago posted electrical schematics of the Vista was 2013 so you might want to download the 2013 wiring diagram drawing for your particular model. It is very close to the current wiring as Winnebago has not changed much DC wise on the high end Vistas over that time frame other than when they started calling them Vista LX and then Adventurer. There are some errors in the 2013 wiring diagram drawing in particular so far as the chassis electrical box and battery compartment are concerned, they did not show all of the large ANL fuses that are present to protect the wiring from overheating if there is short or catastrophic DC failure.

Unfortunately that can't be said for the value priced Vista models that stopped having the chassis disconnect switch and relay and that also stopped using the bi-directional BIRD to save a few dollars of the manufacturing cost so they could be sold cheaper.

[TravatoJohn]

Randy, this was a very nice presentation. Thanks for your input to the group.
Travato John