[brian_]

LiPo's are used in RC aircraft where C-Rates run 20C or greater continuous. Extremely dangerous lithium batteries notorious for catching fire.

They do have a application in EV used as Drag Racers ...

I'll note that these comments are specifically about LiPo (lithium-ion polymer) cells, not all lithium cell types.

(1) Lithium batteries have been used heavily in all EV's, not just drag racers...

Of course - every current production EV (and plug-in hybrid) uses some form of lithium battery, and I doubt that anyone is suggesting otherwise. The drag racing comment was about LiPo cells, specifically.

 

[brian_]

(2) You get different voltages from configurations that are higher, such as a 4S configuration that would have a nominal voltage of 14.6V...

I think it's safe to assume that everyone is this conversation is well past the extreme novice level at which they need someone to tell them that adding cells in series increases the pack voltage.

 

[brian_]

... However, I don't think weight is much of a concern in the case posted here anyway.

That's for sportcoupe to decide, but I think that weight is a significant concern for such a large battery in a small RV. Weight (and weight distribution) is always a concern in RVs, and we're talking about energy storage capacity at least four times as high as is typical for the base configuration of a small RV (which usually has a single 12V lead-acid battery of 80 to 110 Ah capacity), and double the capacity typically carried by large RVs (two GC2 6V, for about 230 Ah @ 12V).

Weight may be the most common reason given by RV owners for wanting a lithium battery.

 

[sportcoupe]

So I can see the possible benefits of using solar if the house battery is FLA (or AGM). The major one is 100% charge several times a week. I understand I could plug in if readily available too. It isn't likely I'd run a genny to get a proper absorption charge on a large house battery bank.

LFP is another matter. I could invest the money for a larger house battery instead of running solar. I suppose a ~800Ah LFP pack would easily handle my crazy inverter ideas.

If I go LFP, I'd go Calb now after some study. Trouble is they discontinued the CA400 cells. The largest they make is 180Ah. Using them, there's no way to single string a 12v pack. I'd have to parallel.

I've had bad experience in paralleling in the past without a BMS. Can a 3P4S or 4P4S LFP pack be made to last without breaking the bank even more? Are CA180 cells readily available still?

What's the best way to bulk charge LFP house battery using a van alternator?

 

[Emyr]

Weight may be the most common reason given by RV owners for wanting a lithium battery.

That along with more Wh in the same battery compartment and faster charging.

 

[Emyr]

What's the best way to bulk charge LFP house battery using a van alternator?

Don't. Save fuel and use a mains charger since LFP should accept a faster charge rate than Lead-based chemistries.

 

[sportcoupe]

That's for sportcoupe to decide, but I think that weight is a significant concern for such a large battery in a small RV. Weight (and weight distribution) is always a concern in RVs, and we're talking about energy storage capacity at least four times as high as is typical for the base configuration of a small RV (which usually has a single 12V lead-acid battery of 80 to 110 Ah capacity), and double the capacity typically carried by large RVs (two GC2 6V, for about 230 Ah @ 12V).

Weight may be the most common reason given by RV owners for wanting a lithium battery.

The vans I'm looking at have a payload of 4500 pounds. That is a lot available for batteries and creature comforts inside the van.

 

[sportcoupe]

Don't. Save fuel and use a mains charger since LFP should accept a faster charge rate than Lead-based chemistries.

I would need a really LONG extension cord. My last trip was almost 8000 miles.

 

[Emyr]

Buildings other than your home contain AC sockets. You could even use an EV-style connector.

 

[sportcoupe]

Buildings other than your home contain AC sockets. You could even use an EV-style connector.

You are suggesting it is not possible to be mobile with a LFP 12v battery pack. That's just not true. Mains isn't required while on the road. You expect me to hunt for a plug-in after driving all day in a camper van?

What the heck am I going to do with an EV style connector? Quick charge my 12v pack?

 

[brian_]

Buildings other than your home contain AC sockets. You could even use an EV-style connector.

At an EV charging station? We've had that discussion in this forum, and I think that the consensus is that this would be unacceptable to EV owners. Even using 240 V AC power to run a charger (not trying to fast-charge with high-voltage DC) I'm not sure that the charging station would maintain power when only a few amps are being drawn.

EV charging stations are rare, to say the least, in places where one might want to camp.

Campsites with power are very common... if that is the type of place one wants to camp.

 

[john61ct]

Best for flexibility is to have multiple sources, but with LFP and such high usage, solar would be pretty redundant.

You need a mains charger for the genset anyway, so ready for shore power when you come across it already are you.

 

[sportcoupe]

So driving all day, there's no way to charge LFP house battery? Seems very odd.

 

[john61ct]

Of course if you drive more than a few hours, not even every day, just most days, with a good setup going into a big LFP bank, that covers a lot of usage.

But that is a very unusual usage pattern. For me, I may stay put 2-3 weeks at a time. Limiting factor is usually water.

Are you a logistics owner-operator ?

 

[sportcoupe]

Back to my question then. What is the best way to charge LFP house pack off the alternator while driving? Electronic isolator relay ? Sterling Battery to Battery charger? Something else?


No, I'm not an owner operator. I am a tourist on extended vacations and like to travel. It will also be my daily driver as I am not retired (yet).

 

[john61ct]

Define best.

The keys are:

user-custom adjustability of setpoints

the ability to limit current drawn by the bank so as to prevent damaging overheating

Sterling BB does these, and is portable with the bank, can be used to regulate any old charge source.

No mods to the vehicle.

But you need more than one if 60A is not enough for you

If the vehicle allows the alternator to be adapted to use an external VR, I recommend Balmar's MC-614.

This lets you get the maximum amps out of your alt.

As heat rises, throttles current while keeping voltage at your desired setpoint.

But then every other source needs fancy regulation, and the money spent only applies to that vehicle.

 

[brian_]

What is the best way to charge LFP house pack off the alternator while driving? Electronic isolator relay ? Sterling Battery to Battery charger? Something else?

If the same alternator is used for vehicle power and to charge the house battery, you probably won't have sufficient voltage so I think a DC-to-DC charger would be advisable. Certainly a relay-type isolator would be a good idea; that's normal equipment for motorhomes and trailer tow vehicles.

If you have two alternators, with one dedicated to charging the house battery, then an external regulator set to suit the house battery might work well.

 

[sportcoupe]

If the same alternator is used for vehicle power and to charge the house battery, you probably won't have sufficient voltage so I think a DC-to-DC charger would be advisable. Certainly a relay-type isolator would be a good idea; that's normal equipment for motorhomes and trailer tow vehicles.

If you have two alternators, with one dedicated to charging the house battery, then an external regulator set to suit the house battery might work well.

Relay-type isolator for motorhomes and trailer tow vehicles but they don't normally use LFP house battery. I'm thinking DC to DC charger is best.

 

[sportcoupe]

Define best.

The keys are:

user-custom adjustability of setpoints

the ability to limit current drawn by the bank so as to prevent damaging overheating

Sterling BB does these, and is portable with the bank, can be used to regulate any old charge source.

No mods to the vehicle.

But you need more than one if 60A is not enough for you

If the vehicle allows the alternator to be adapted to use an external VR, I recommend Balmar's MC-614.

This lets you get the maximum amps out of your alt.

As heat rises, throttles current while keeping voltage at your desired setpoint.

But then every other source needs fancy regulation, and the money spent only applies to that vehicle.

Sterling BB has a high power 120 Amp version now. Looks sweet.


https://www.sterling-power-usa.com/...probattc-batterytobatterycharger12vto12v.aspx

 

[john61ct]

Nope, that's their older BBW line, not appropriate for LFP, not user adjustable.

But Charles has stated up to 240A BBs coming out "soon"