LiFeP04 Drop In Batteries

[Reed Cundiff]

Dan

Our 19' Roadtrek is at a different scale: smaller fridge, air conditioner, micro-wave etc and has 1/3 of the solar (Roadtreks have limited real estate - 415 W of solar requiring two different controllers) and half the LFP battery suite with about 4.5 kW-hrs as opposed to 9 kW-hrs.

We have had bad experience with line power in Canada, US, and Mexico (lost microwaves in Baja and Yucatan) so both rigs are set to take power through battery chargers to battery and then PSWI for AC. It just takes a switch to utilize line power directly but have not done this in four years. We are currently visiting younger son and family on Fort Collins so we are plugged in with 5th wheel (15 amp extension cord to battery chargers).

Reed and Elaine

[Luv2go]

Originally Posted by computerguy

Curious where you got 1000Ah lithium for $5500
.....

Here's an example of 1000AH at 12V of bare cells for less than $5500. These were manufactured in 2015, however LiFePO4 batteries have a long demonstrated shelf life (Jack Rickard from EVTV tested several CALB cells that had been sitting on a shelf for two and a half years and found minimal capacity degradation).

It would take 48 of these to make up a 1000AH battery, so this may not be the best cell to use for that system, however I bought 16 of these in November 2016 for our new-to-us Roadtrek and have had good results. If you e-mail the seller you will be able to reduce the shipping cost, but even at the listed costs the total for 1000AH at 12V is $3890.

[Timon]

Originally Posted by Reed Cundiff

... both rigs are set to take power through battery chargers to battery and then PSWI for AC...

This is by far the best way to run a coach but it does take a good size battery charger, a larger inverter good energy management especially in larger coaches.

[Reed Cundiff]

Timon

Thanks, it seems to work well. We are currently set up in younger son's backyard. We did run 15 amp power cord to his house since it is raining unseasonly in Fort Collins. If sun were shining we would not.

How do you fit all those big dogs in your rig?

Reed and Elaine

[BatteryPro]

Originally Posted by baphenatem

The only thing that I don't like on those LifeBlue batteries is the 100 Amp current limit for pretty much all of their models. It seems like they're trying to get by with only one type of BMS board, instead of having different ones tailored to the various Ah capacities. If you are paralleling them it's probably not a problem.

Hi Tom,

All other drop-in Li-ion batteries have the same 100 Amp limitation due to heat generation and space in the battery case for the larger components that can pass more current.

You are correct, by paralleling the LiFeBlue battery, you are increaseing the current capability; 2 gives you 200 Amps continuous, 3 is 300A and so on.

The LiFeBlue manufacturer is now developing a 200 ampere EMS board with high efficiency components that will limit the heat. These will only be in the 200AH and 300AH battery packs. The 75AH, 100AH and 150AH will still pass 100A continuous. That will mean you can use a single battery for up to a 2kW inverter. Should be available in about 3 months.

73,
Larry

[harryn]

Actually there are some very good LiFe batteries that are rated at 150 amp output continuous. I use them to build up 48 volt systems.

As a practical matter though, if you are running more than 100 amps through a wire, it makes sense to consider moving from 12 volts up to 48 as your pack voltage.

- The entire solar charge control setup shrinks in size and cost.
- The inverters are more efficient and can actually hit the output specs
- 12 volt loads are fed from 48 - 12 volt converters
- Wire losses can easily be made negligible
- Even an AGM based system gains substantial benefit using a 48 volt pack. I just finished installing one for one of my wife's friends in her sprinter.

I can't imagine going back to a 12 volt battery pack based system. There are very good reasons why many off grid homes are now mostly 48 volt.

[CountryFit]

i like higher voltage system too, thinking that next coach (if) would go that route. however, on the down side, (1) you need to get a 48v inverter like magnum ms4448pae; (2) you can't utilize the alternator power to charge the house batteries while you are driving, unless you invest $$$$ upward charging management device - not sure such a thing is available, or let alternator output 48v (then you would have problem to charge the starting battery). subsequently, you would need to rely on solar and/or generator to charge the battery pack. it's good but need to know the challenges.

[Timon]

It’s not unreasonable to just add a second alternator to feed a LiFePO4 bank as you can better control the charge to the Lithium. With a 48V bank IMHO it’s the only way to go.

[BatteryPro]

Hello harryn,

Originally Posted by harryn

Actually there are some very good LiFe batteries that are rated at 150 amp output continuous. I use them to build up 48 volt systems.

Please tell us who makes a drop in replacement with 150 amp continuous output.

Originally Posted by harryn

...As a practical matter though, if you are running more than 100 amps through a wire, it makes sense to consider moving from 12 volts up to 48 as your pack voltage….

We daily design and install power systems that use well over 200 amps. No problems with wire size. Using the right size wire for the job is decided by simple math and following the NEC.

48 volt DC systems are great for most off grid or standby power systems. It is very rare that they would be practical in an RV compared to a 12 or 24 volt system with all the additional costs. Using 48 volt battery system in an RV can also put unsuspecting people such as service technicians at risk of electrical shock. It also increases your fire risk due to parallel arc fault potential from the high voltage PV solar array. We do not recommend installing a 48 volt system in an RV.

Consider:
1. Few inverters are designed for mobile use making them a shock hazard without the neutral to ground automatic switching.
2. You loose the ability to charge from an alternator which is one of the best charge sources RV’ers have.
3. Adding a second 48 volt alternator is expensive.
4. You must convert the 48 volts down to 12 volts for house use which will add cost.
5. Your PV open circuit voltage will be above 60 volts. This is viewed as High Voltage by the NEC, NFPA. Most such systems would not be approved as in compliance. What is your Voc?
6. Parallel Arc Fault danger greatly increases. This is dangerous because you can’t stop the fire or arcing without blocking the sunlight to the PV modules. What kind of wire did you install and how did you protect it?
7. Potential law suit for injury or death from the shock hazard you create. Think of all future people that may come in contact with your AC/DC system that are unaware of the hazard.
8. Potential rejection of insurance claim do to many code violations.

Originally Posted by harryn

...
- The entire solar charge control setup shrinks in size and cost.

Any cost savings using 48 volts is swallowed up by the other equipment required to operate at that voltage. The same amount of PV solar power is required no matter what voltage you operate at. Power does not change based on voltage.

Originally Posted by harryn

...
- Even an AGM based system gains substantial benefit using a 48 volt pack. I just finished installing one for one of my wife's friends in her sprinter....

There is no difference using 48 volts or any other voltage to charge a particular battery chemistry as long as the proper charge procedures are followed.

I hope the reader will consider these things before attempting a 48 volt battery system in an RV.

Larry

[CountryFit]

thank you larry! really like this kind of informed advices, for "experienced", and new comers!

[Dan McMartin]

I'm sure moving up to 24 volts has advantages...maybe even 48 if you know what you're doing...but for most of us, that's just a lot of unnecessary hassle.

12 volt systems work just fine and are all most RVers need, save for the solar array which is pretty easy to bump up to 24 volts. Heck, most of us can get by with 4 golf cart batteries and 400-600 watts of solar. Plenty of power to run the coach for a day or three and enough solar to charge the batteries back up. Add generator to the mix and you're off grid for as long as long as your tanks hold out.

[harryn]

The advantages of 24 and 48 volt systems are widely recognized and quite safe. 24 volt is widely used in boats / marine applications, and 48 volts is more common than you might think.

You are correct that for RVs with the primary power use being to drive an exhaust fan and a few lights, the battery pack voltage doesn't matter.

Once the RV power use starts to need 2000 watts of 120 vac, it does make a difference in inverter efficiency, and for the 4000 - 8000 watt region it is a must.

The fire risk is actually lower with 48 volt vs 12 volt if powering a 3000 watt inverter because the current is so dramatically reduced.

24 volt systems can be done by anyone but I agree that it is better (but not required) to have someone with 48 volt experience install that type of system as there are definitely more details that need to be cared for.

Charging from the existing alternator is not a problem in a system that is properly designed - we do it all of the time.

[harryn]

Originally Posted by Dan McMartin

I'm sure moving up to 24 volts has advantages...maybe even 48 if you know what you're doing...but for most of us, that's just a lot of unnecessary hassle.

12 volt systems work just fine and are all most RVers need, save for the solar array which is pretty easy to bump up to 24 volts. Heck, most of us can get by with 4 golf cart batteries and 400-600 watts of solar. Plenty of power to run the coach for a day or three and enough solar to charge the batteries back up. Add generator to the mix and you're off grid for as long as long as your tanks hold out.

Dan, you are right when it comes to each individual case.

This forum section is called "going green" and to me it entails more than just solar panels and running the generator less. It also includes our larger environmental responsibility.

It might not be obvious, but every lb. of thick gauge wire that we use also results in 10 - 20 lbs of waste rock dust that is forever contaminated with the acid used to extract the copper from it.

By moving from 12 volts to 24 volts, the potential exists to reduce this waste by 50%, and for 48 volt systems, by 75%. This is why the auto industry is moving toward 48 volt systems and over the next 5 years it will be increasingly common.

BTW, I am not in any way any kind of super environmentalist type - this is just common sense and economics.

[cruzbill]

Just a reality check here, but anyone saying that towing or pushing an RV with an internal combustion engine is somehow 'going green'; Think about it when you fill up your fuel tank. I enjoy the RV lifestyle, I have 7kw of solar on our house, but I don't kid myself into thinking I'm saving the planet for my grandkids (of which I have none). We're burnin' it so they can't use it........

Can technology get us out of the mess we're in?