Considering Lithium upgrade for 2020 Minne plus 27 BHSS

[xiques]

Hi everyone

This is Jack. I have this 2020 Minnie plus 27 BHSS for almost 3 years. I Added one more 12V battery to make it paralleled with existing 12V.

when off grid
I charge it with 2000 Watts generator and 200 watts Renogy Solar panel, most the time about 2-3 hour generator and 4 hours of sunlight but my unit run out power in the evening, wife is upset when no water pump and furnace at nights 😂

I have done some reading in this form and other places online for battery upgrade project. But still want to shout out to everyone to see if any suggestions

Thanks
Jack

[Marine359]

Hi Jack,
You might want to first take an energy audit.
An audit reveals to you how much power you consume on a typical camping day.
You can find out how many amphrs you consume in a day by installing a negative shunt monitor (very inexpensive and you’ll need it forever), or by recording your battery voltage, starting and ending over a 24 hour period, with no generator or solar charging. The drop in voltage over the 24 hour period will tell you how many amphrs you consumed, by looking it up on the chart that corresponds with your battery. Once you have your daily amphr consumption, multiply that number by the number of consecutive days you want to dry camp in order to arrive at the number of amphrs you’ll need. You can, if you like subtract the amount of power you put into the batteries with generator and solar, but it will be much better if you size your new batteries without accounting for charging routine.

It is a non-trivial matter to upgrade to LiFePo4 batteries. There’s the cost of the batteries, a new charging system, possible new wiring, and installation. If you’re not capable of doing it yourself, you’ll pay for at least 4 hours of labor. A less e pensive solution is to just buy two 6v GC2 batteries, wire them in series and put them on the tongue replacing your existing batteries. This will give you 230 total amphrs, and up to 80% of that will be useable on an occasional basis, or 50-60% usage on a routine basis. This solution can use existing charger, and only a couple of heavy cables to connect the two batteries. Total cost under $300.

If you just added a second 12v Marine grade battery, you’re only getting about 75 useable amphrs before your batteries give up. And you’ll kill thru real fast if you routinely run them all the way down.

If you have an absorption fridge, you should be able to run your camper on less than 40 amphrs per day including furnace and all other normal 12v loads. Decide on what budget expenditure will give you the amphrs you need and go with that. LiFePo4 is only necessary if you have a compressor fridge, which is not likely for your model year. A switch to LiFePo4 will cost over $3,000 if it’s DIY, $3,500 if it’s not DIY.

[xiques]

Originally Posted by Marine359

Hi Jack,
You might want to first take an energy audit.
An audit reveals to you how much power you consume on a typical camping day.
You can find out how many amphrs you consume in a day by installing a negative shunt monitor (very inexpensive and you’ll need it forever), or by recording your battery voltage, starting and ending over a 24 hour period, with no generator or solar charging. The drop in voltage over the 24 hour period will tell you how many amphrs you consumed, by looking it up on the chart that corresponds with your battery. Once you have your daily amphr consumption, multiply that number by the number of consecutive days you want to dry camp in order to arrive at the number of amphrs you’ll need. You can, if you like subtract the amount of power you put into the batteries with generator and solar, but it will be much better if you size your new batteries without accounting for charging routine.

It is a non-trivial matter to upgrade to LiFePo4 batteries. There’s the cost of the batteries, a new charging system, possible new wiring, and installation. If you’re not capable of doing it yourself, you’ll pay for at least 4 hours of labor. A less e pensive solution is to just buy two 6v GC2 batteries, wire them in series and put them on the tongue replacing your existing batteries. This will give you 230 total amphrs, and up to 80% of that will be useable on an occasional basis, or 50-60% usage on a routine basis. This solution can use existing charger, and only a couple of heavy cables to connect the two batteries. Total cost under $300.

If you just added a second 12v Marine grade battery, you’re only getting about 75 useable amphrs before your batteries give up. And you’ll kill thru real fast if you routinely run them all the way down.

If you have an absorption fridge, you should be able to run your camper on less than 40 amphrs per day including furnace and all other normal 12v loads. Decide on what budget expenditure will give you the amphrs you need and go with that. LiFePo4 is only necessary if you have a compressor fridge, which is not likely for your model year. A switch to LiFePo4 will cost over $3,000 if it’s DIY, $3,500 if it’s not DIY.

Thank you so much Marine
such a detail answer in many way
But after talk to my RV dealer Today , I decide to get the Renogy 12V 200Ah Lithium Iron Phosphate Battery w/ Bluetooth and Renogy One M1 as bundle.
They said because Renogy battery have BMS build in, so I do not need DC-DC charger in this case.

Thanks Again

[Wakullabob]

For less than a thousand dollars I switched to 200 amp lithium and a converter conversion, all DIY . Why would you need larger wiring , all the draws are the same !

[Marine359]

Originally Posted by Wakullabob

For less than a thousand dollars I switched to 200 amp lithium and a converter conversion, all DIY . Why would you need larger wiring , all the draws are the same !

Sorry, I should have explained.
Many folks add an inverter after upgrading battery. The inverter to battery connection requires 1/0 or 2/0 cable. In my case, I went with a 2000w inverter/charger.

[creativepart]

Originally Posted by xiques

They said because Renogy battery have BMS build in, so I do not need DC-DC charger in this case.

Yes and no.

Virtually all commercially available 12v LFP batteries have an internal BMS, this isn’t why you wouldn’t need a DC2DC charger. RV Dealers are rarely reliable sources of info on newer tech like this.

The reason you don’t “need” a DC2DC charger is because you have a Travel Trailer and tow vehicle. The charge line from your tow vehicle doesn’t provide that much power to your new LFP battery. If you had a motorhome the battery is connected directly and to the motorhome’s alternator and this can draw too much power from the alternator. So, many remove the direct alternator connection and place a DC2DC charger inline to charge the LFP battery while driving.

As I mentioned earlier you don’t “need” a DC2DC charger but you may “want” one. Your tow vehicle’s alternator may not be able to properly charge your new battery while driving due to that charge line output I mentioned. So you may want to install a DC2DC charger to take over that role.

The BMS in your new LFP battery protects the battery from overcharging and other protections but it’s not the same as an external lithium-specific smart charger. The BMS saves the battery from ruin but you still need to design your system to properly charge and maintain your new LFP battery.

I have two of the Renogy 200aH LFP batteries in my motorhome and they’ve been terrific. You’ll find the new battery very capable.

[Marine359]

Agree with Creativepart,
A dc/dc charger is really great for lead acid batteries, and is a worthwhile investment. Not so much for LiFePo4. If you have a towable, it can be tricky, or you have to pay somebody a lot to run cable between your tow vehicle battery/alternator and the bumper. The 7-pin wires are too small for high amperage. An easier and less expensive solution is just put some solar on the roof wired to a mppt controller near the battery. On a sunny day 3x 100w panels in series will output nominally 3x 18 volts driving a mppt to a very high power point. MPPT controllers love high voltages. The controller will likely output more than 150 watts. So, with no loads on the battery, a 100ah LiFePo4 will charge to 100% in a single day of driving.

Solar cost 3x $100 for panels, and $250 for controller. Easy install and charges when not driving.

DC/DC cost $225 for an Orion and $50 for wiring, harness, fuses, and plugs. Hard install, and does nothing while not driving.

[BobC]

I've had good experience with two 6V golf cart batteries on my two TTs and now my MH. I had 200W of solar on my TT which handled our loads but we were careful with our power usage when off the grid. We used a Honda 2000i generator for the microwave. We could go several days off the grid without any issues as long as we had a reasonable amount of sun. Two GC batteries can be purchased for about $120 at Sam's Club. I couldn't find a Costco price but they're usually about the same.

Even so, your power usage seems high. If two dual purpose "Marine" batteries + solar + generator won't get you through the day, I'm not sure if two GC batteries or even a basic Lithium installation would. One thing that uses a lot of power is your propane heater since the blower runs on 12V. Another high usage item is a CPAP machine. When you're offgrid, you need to "think camping", not "RVing", turn lights off when you're not using them, don't watch TV all the time, etc. Marine359's advice about monitoring your power usage is excellent. You definitely need to do this before jumping to Lithium to make sure you're new system is properly sized. Victron's SmartShunt at about $130 is a great option:

https://www.amazon.com/Victron-Smart...s%2C158&sr=8-5

Personally I wouldn't trust a dealer, either in terms of quality, knowledge or price. A good, independent shop is a better option if you're not up to DIY. In any case educate yourself as much as possible about the ins and outs of LiFePO4 by reading as much as you can on Winnieowners and other forums, especially WO's sister site IRV2.com.

Note: Most experienced owners, don't use dealers for anything but warranty work. They're priority is always on sales. Here's the type of shop you're looking for:

Mobile RV Service and Parts - Galt California

[Marine359]

BobC is absolutely correct about batteries. 2x 6v GC is always the most economical solution, as long as you can handle the weight of the two batteries on the tongue, and you have normal TT daily power consumption. Your costs will include, a bigger battery box, the shunt, the two batteries and some cables. All in less than $400. If you have an absorption fridge and no weight issues, stick with BobC’s recommendation.

[Old Navy]

I currently have a similar setup, but have 2X 6V 220ah golf cart batteries. It works for now, but we don't use a lot of power. One of the problems with our rigs is the crappy WFCO power converter. Add in a 20-30 foot length of AWG 6 wire between your converter and batteries and the voltage drop slows charging more. Running my gennie in the evening seems like wasted effort, as I'm only pushing a few amps. Some people just upgrade the converter, but if/when I upgrade to lithium, I'll be co-locating the charger with the batteries and shutting off the converter.

Like BobC said, you seem to be using a lot of power. I learned a lot about my power consumption, charging and SoC (state of charge) when I installed a battery monitor. I installed a Victron BVM-712, but there are cheap options if you don't need or want a lot of extra features. I find that after my first day, my batteries rarely get back above 90% SoC and are usually 50% or higher in the morning.

[creativepart]

Originally Posted by Old Navy

One of the problems with our rigs is the crappy WFCO power converter.

A standard Converter in most TTs is rated to put out 45-amps. But you’ll hardly ever, if ever, see that much going into your batteries. The standard Converter in your RV isn’t really “crappy” just not optimized for today’s Boondocking desires. If you travel from RV park to RV park, all with power hookups, then your Converter is perfectly adequate. Manufactures have seen that kind of camping as the norm for quite a few years.

Keep in mind when choosing battery type that the thicker plates in a 6v battery take longer to recharge than a 12v battery of the same amp hour rating. Lithium batteries are vastly faster charging.

[Old Navy]

The WFCO converter might be "fine", it just performs poorly in my system. When I plug in or run the genny with a low battery, I get less than an hour of good charging before it drops from BULK to ABSORPTION. The converter drops into FLOAT when the batteries are still at 80-85%. My converter is at the extreme rear of my trailer, batteries on the tongue, so I'm charging through about 30'-35' of AWG 6, contributing to the problem. Of course it was fine with the little group 24 "marine" battery that came with the trailer, so I'm asking the system to do something beyond what it was designed for.

[creativepart]

Originally Posted by Old Navy

The converter drops into FLOAT when the batteries are still at 80-85%.

Here’s what I’ve read on this topic from other websites:

Stage 3 | Float Charge
Some chargers enter float mode as early as 85% state of charge but others begin closer to 95%. Either way, the float stage brings the battery all the way through and maintains the 100% state of charge. The voltage will taper down and maintain at a steady 13.2-13.4 volts, which is the maximum voltage a 12 volt battery can hold. The current will also decrease to a point where it's considered a trickle. That's where the term "trickle charger" comes from. It's essentially the float stage where there is charge going into the battery at all times, but only at a safe rate to ensure a full state of charge and nothing more. Most smart battery chargers do not turn off at this point, yet it is completely safe to leave a battery in float mode for months to even years at a time.

[Ray,IN]

6V batteries in series do not multiply amp-hrs, only voltage. I doubt you can get 230 Amps from one 6V battery, you do get one 12V battery.


A primer for, The 12V side of Life.http://marxrv.com/12volt/12volt.htm

[creativepart]

Originally Posted by Ray,IN

6V batteries do not multiply amp-hrs, only voltage. I doubt you can get 230 Amps from only 2 6V batteries, you do get one 12V battery.

There are dozens of 220 and 225 amp hour 6-volt golf cart deep cycle batteries available in many places including Amazon and various battery reseller locations.

So, 2-225 amp hour will get him one 12v 225aH battery bank. True, it's not 230aH, but seems like 225aH is close enough. Trojan, however even sells a 240aH 6v battery.

[Old Navy]

Originally Posted by Old Navy

I currently have a similar setup, but have 2X 6V 220ah golf cart batteries.

Originally Posted by Ray,IN

6V batteries in series do not multiply amp-hrs, only voltage. I doubt you can get 230 Amps from one 6V battery, you do get one 12V battery. A primer for, The 12V side of Life.The 12volt Side of Life (Part 1)

220ah is pretty common for 6V GC batteries. Also, I'm a retired ET, so understand the technical side pretty well. Not that I'm beyond learning or helpful suggestions, and I appreciate yours.