Switching house batteries to lithium

[Mark_K5LXP]

consider changing this to a 48-volt system

What are you going to charge 48V batteries with?

Mark B,
Albuquerque, NM

 

[John From Detroit]

What are you going to charge 48V batteries with?

Mark B,
Albuquerque, NM

48 volt charge controllers are very common in the Solar field (I will explain) and in the "Home power storage" field as well. Devices like the Power (Tesla) which uses a 50 volt battery.

Some areas limit the storage battery to 48-50 volt Thus chargers in that range.. Very common.

 

[DonTom]

48-volt converter.

What are you going to charge 48V batteries with?

Mark B,
Albuquerque, NM

I assume somebody makes a 48-VDC converter and such stuff.

But I don't know if I should use two DC2DCCs so both batteries can charge as I drive. I don't want to overload the alternator, but perhaps I can make a setup which charges one at a time. Called a SPDS switch. Or deduce the current to both. I have not thought about it much yet. I am not even sure if I will bother with it.

Maybe some rainy day when I am extra bored.

-Don- Verdi, NV

 

[zulutron]

What are you going to charge 48V batteries with?

A 48V Victron Inverter/Charger

 

[DonTom]

A 48V Victron Inverter/Charger

That looks perfect if I do decide to do it.

Nice specs on both the converter and inverter.

-Don- Auburn, CA

 

[Primerump]

That looks perfect if I do decide to do it.

Nice specs on both the converter and inverter.

-Don- Auburn, CA

I usually spec the 3kVA version for 30amp RV's, mine included.. it's a good unit and will act as a UPS, control generator and prioritize solar when on shore power too.. I can assist with the programming/configuration stuff too..

 

[DonTom]

I usually spec the 3kVA version for 30amp RV's, mine included.. it's a good unit and will act as a UPS, control generator

One of my motorhomes is a 50-amp (2022 Class A), the other is a 30-amp (Y2K Class C).

-Don- Auburn, CA

 

[Mark_K5LXP]

Yes, it was an obvious answer to a basic question but what you're proposing to do is engineering, buying and integrating a whole new storage system. Perfectly OK if that scratches an itch you have but that's a long way around the block to go unless it solves a pretty direct and specific operational issue. I guess I'm at a stage in life of being careful what problems I choose to solve and fixing something that isn't necessarily broken would be lower on my list. But it will be fun to watch you do it...

Mark B.
Albuquerque, NM

 

[Primerump]

Parallel connections do not scale perfectly. Even miniscule differences in cables and connections can cause a large disparity in current flow. Not just in cabling, that's actually a pretty stable constant. Connections and components become a large variable that can easily get away from you in the form of both lost power, voltage drop and long term reliability. A basic crimped cable terminal, copper nut and bolt, and another terminal (as you'd find on a bus bar) can easily have a few milliohms resistance. Run a hundred amps through that and you're dropping a quarter volt and dissipating 25 watts. 25 watts is a lot of power in a small volume like that - it's gonna get toasty. Run that load frequently and that junction is getting cycled hot and cold, expanding and contracting which can eventually loosen the connection. Causing even greater drop, a hotter connection until eventually it either opens up or melts something. Fuseholders and fuses can have even more resistance between their terminations, end/blade contacts and the fuses themselves. No two batteries will have the same exact internal impedance and connection resistances. Getting them to share identical currents into large loads is difficult. Throw in a number of connections, cables and components and the variables only increase. High(er) voltage can have challenges but low voltage/high current has it's own set of subtleties to deal with so there's no universal solution. The components and configuration are dependent on the end application.

Mark B.
Albuquerque, NM

agree 100%.. paralleling batteries is to be avoided if possible.
standard practice for off grid is to parallel CELLS first to achive capacity, then series those cell banks to achive desired voltage. exception to that is if cells are available at the desired capacity. in some off grid designs I have utilized 2000Ah 2V FLA cells rather than paralleing lower capacity units.

 

[Primerump]

One of my motorhomes is a 50-amp (2022 Class A), the other is a 30-amp (Y2K Class C).

-Don- Auburn, CA

the 3kVa unit is fine for most 30A applications, 50A is a little more complicated depending on the requirement to have true split phase 240V or not.. most US motorhomes appear to not require true split phase, but there are exceptions for those that have 240 V appliances such a washer.
then I would suggest 8kVa

 

[DonTom]

the 3kVa unit is fine for most 30A applications, 50A is a little more complicated depending on the requirement to have true split phase 240V or not.. most US motorhomes appear to not require true split phase, but there are exceptions for those that have 240 V appliances such a washer.
then I would suggest 8kVa

There is no 240 VAC stuff in my 50-amper RV.

-Don- Auburn, CA

 

[Primerump]

There is no 240 VAC stuff in my 50-amper RV.

-Don- Auburn, CA

that simplifies the install to one inverter, both "phases" connected as if you were using a 30 to 50A adapter.
a true 50A split phase requires much more hardware.

I will post typical solutions for both..

 

[Sunnyfalls]

Just FYI, having 240VAC circuit capability and 14,400 Watts power capability is a trivial, low cost modification if you are capable of doing the work yourself.

Replace old WFCO, modify it with new chager? - Fiberglass RV

I have a 13' 2001 Scamp . I replaced the power center when I bought it, can't recall exactly why, but I put in a new (at the time) WFCO. The Scamp has been in storage unused for over 10 years and it

www.fiberglassrv.com

And we actually use our 240VAC and 14,400 Watt power capability when we are paying for a hookup to avoid using any of our propane at all. Our electric/propane tankless water heater is 240VAC and 6500 Watts. Our electric induction cooktop is 240VAC and 3500 Watts. Our electric heater is 120VAC and 1500 Watts. And when we have a hookup, we run our air conditioner, refrigerator and all our other appliances on 120VAC too which includes our coffee maker, hair dryer, Starlink Internet, toaster oven, microwave oven, toilet heated bidet seat and vacuum cleaner.

Gayle & Bob
"Los Gatos Casita"