Lithium batteries, are they really that expensive?

[TitanMike]

Originally Posted by babock

The people that go 24V are the ones that are going to power Air Conditioning. Then there are the ones that somehow get in their head that 24V has to be better for everything else which is kinda ridiculous.

Buy a Victron battery shunt and you will see how low all your loads really are...including your slide.

If I was running A/C from my battery bank I think I'd not stop at 24 volts but rather make the jump to 48 volts.

[babock]

Originally Posted by TitanMike

If I was running A/C from my battery bank I think I'd not stop at 24 volts but rather make the jump to 48 volts.

Would just have to make sure you had high enough voltage solar panel array and the larger Victron solar controllers to do it. If I was going to run A/C and had a large trailer, I would probably use Tesla modules. Now those are science experiments.

[Half Ton Heavy]

Originally Posted by babock

Wopud just have to make sure you had high enough voltage soar panel array and the larger Victron solar controllers to do it. If I was going to run A/C and had a large trailer, I would probably use Tesla modules. Now those are science experiments.

I was initially going to Tesla 85, based on the Mortons video series.
Then I saw the videos of those batteries burning, and the drop in prices of large capacity LiFePO4 cells, and it was a no brainer. I know from using A123 cells that they are pretty tolerant of abuse ( comparatively) vs. the Tesla.
Lithium is getting cheaper by the day.

[babock]

Originally Posted by Half Ton Heavy

I was initially going to Tesla 85, based on the Mortons video series.
Then I saw the videos of those batteries burning, and the drop in prices of large capacity LiFePO4 cells, and it was a no brainer. I know from using A123 cells that they are pretty tolerant of abuse ( comparatively) vs. the Tesla.
Lithium is getting cheaper by the day.

If I used Tesla batteries, they would be in a fireproof metal box. I will never have to worry though...I have ZERO desire to get a trailer that big and ZERO desire to ever camp where I need AC.

[Half Ton Heavy]

Originally Posted by babock

If I used Tesla batteries, they would be in a fireproof metal box. I will never have to worry though...I have ZERO desire to get a trailer that big and ZERO desire to ever camp where I need AC.

At least in the Mortons video, they did not do it for air, (although he demonstrated it), just capacity. You would need three Tesla modules to use air for a day. And then the associated solar, etc. It is not really an attainable goal I think. They do run a dc fridge cooling system from jc refrigeration with it. If you’ve not seen his Tesla videos, they are interesting.

[woodruff13]

Riverbend, thanks for doing this first. I wrote up my experiences at https://www.forestriverforums.com/fo...ml#post2457637



Bill

[Riverbend]

Nice job on the conversion and the write-up! I know I needed and received much help from this forum when I did mine. I especially appreciate the little details you take care to address, like lug sizes for example. I also had to work through most of those same issues, and am planning the Li-BIM swap in the spring before reinstalling the BattleBorn batteries. And giving credit where credit is due, the Li-BIM picture I shared was from Mlmay, another Lithium convert who was one of the huge helpers in my installation process.

[Hclarkx]

I'm surprised that running A/C on battery is being discussed without mention of changing to a mini split A/C. A mini split is not always practical or an easy switch, but where it is, switching to a mini split is far less costly than the battery and solar needed to run the far less efficient conventional roof top A/C. My son and I both run mini splits on modest 12V systems.

[TitanMike]

Originally Posted by Hclarkx

I'm surprised that running A/C on battery is being discussed without mention of changing to a mini split A/C. A mini split is not always practical or an easy switch, but where it is, switching to a mini split is far less costly than the battery and solar needed to run the far less efficient conventional roof top A/C. My son and I both run mini splits on modest 12V systems.

Hard to see how a split system is more efficient, at least mechanically, as on the rooftop units one motor does double duty. Both cool the condenser and push air through the evaporator. A split requires two motors.

As for more efficient compressors I would imagine that more efficient compressors are possible but don't fit the price point required for most RV manufacturers. My Chevy Volt has electric powered A/C but I'd hazard a guess that the compressor alone is as much as a Coleman, Dometic, or Furion rooftop unit complete.

Not saying the split can't work, just figure that there has to be a good reason the industry hasn't jumped on it.

[Rickbike]

I have a 2015 Solera and I'm trying to drop in two 100ah Battle Born Batteries. Your article was very helpful. I'm struggling with where to put the DC to DC charger. Like yours my RV has the battery control center by the steps. You mentioned:I first disabled the factory BIM interconnect relay by disconnecting the wires to the non-grounded side of the relay’s coil. Could you explain this a little more for me. My RV has a solenoid. On the solenoid there are three terminals. The small terminal has all the wires running back to the fuses. I don't exactly understand how this solenoid works so I'm having a hard time figuring out what you disconnected (how you did that) and where you mountered your renogy DC to DC. Any help would be greatly appreciated. Thank You

[JLeising]

Originally Posted by Rickbike

I have a 2015 Solera and I'm trying to drop in two 100ah Battle Born Batteries. Your article was very helpful. I'm struggling with where to put the DC to DC charger. Like yours my RV has the battery control center by the steps. You mentioned:I first disabled the factory BIM interconnect relay by disconnecting the wires to the non-grounded side of the relay’s coil. Could you explain this a little more for me. My RV has a solenoid. On the solenoid there are three terminals. The small terminal has all the wires running back to the fuses. I don't exactly understand how this solenoid works so I'm having a hard time figuring out what you disconnected (how you did that) and where you mountered your renogy DC to DC. Any help would be greatly appreciated. Thank You

On my 2012 Solera:
- I disabled the battery interconnect relay (solenoid) by removing the (small) non-ground wires connected to the relay’s coil. Believe, as I remember, there were two wires on the terminal - I kept the two wires connected together - but not to the terminal (I didn’t want to disable any of the BCC’s other functions). With the coil disconnected, the solenoid will not activate and the batteries (coach and chassis) will remain isolated.
- I mounted the Renogy dc-to-dc (20 amp model) on the front panel of the storage compartment immediately behind the stairs. Connected the dc-to-dc converter to the chassis and the coach batteries (positives) using the (large) terminals of the disabled solenoid. Picked up the required ignition signal (to activate the dc-to-dc converter) from the ignition wire in the BCC. As I remember, I used the coach battery negative connection to the chassis as ground.
-FYI, I used a delay relay on the ignition wire, to avoid loading the chassis battery with the dc-to-dc converter before the engine was running - but I don’t now believe this was necessary, as the ignition wire I picked up from the BCC doesn’t seem to activate until after the engine has started.

My install has been working very well.

FYI, Jim

[Rickbike]

Originally Posted by JLeising

On my 2012 Solera:
- I disabled the battery interconnect relay (solenoid) by removing the (small) non-ground wires connected to the relay’s coil. Believe, as I remember, there were two wires on the terminal - I kept the two wires connected together - but not to the terminal (I didn’t want to disable any of the BCC’s other functions). With the coil disconnected, the solenoid will not activate and the batteries (coach and chassis) will remain isolated.
- I mounted the Renogy dc-to-dc (20 amp model) on the front panel of the storage compartment immediately behind the stairs. Connected the dc-to-dc converter to the chassis and the coach batteries (positives) using the (large) terminals of the disabled solenoid. Picked up the required ignition signal (to activate the dc-to-dc converter) from the ignition wire in the BCC. As I remember, I used the coach battery negative connection to the chassis as ground.
-FYI, I used a delay relay on the ignition wire, to avoid loading the chassis battery with the dc-to-dc converter before the engine was running - but I don’t now believe this was necessary, as the ignition wire I picked up from the BCC doesn’t seem to activate until after the engine has started.

My install has been working very well.

FYI, Jim

Thank you very very much. I think I'm going to install the Renorgy DC to DC 50 amp charger. I don't currently have solar and most likely will add it later. I will let you know how it goes.

[JLeising]

Not aware of anyone actually having a problem, but be aware that apparently the Mercedes “upfitter” guide limits current for an auxiliary battery to 40amps. As the Renogy dc-to-dc units draw 150% of the output current per their spec, that is why I chose the 20 amp version.

https://www.forestriverforums.com/fo...it-215973.html


FYI
Jim

[AlanMoor]

I have been fantasizing about LiFePO4 batteries for the camper I don't even have yet. It's actually part of a larger project of a self-sufficient camper, both for my use, and my sister's (her husband lives in his camper while he is away at work and often has to boondock). One of the things I was looking at was LiFePO4 battery costs, as that is about 1/2 the project (I'll put my calculations in another post as not to hijack this thread). Anyway, I've attached a PDF version of a spreadsheet I came up with. One thing I didn't account for is BMS or heaters.

It seems like this group likes BattleBorn, and they come in at about the same price point as Renology. You can go cheaper with other brands (mostly from E-Bay), but I have no idea about the reliability of those brands.

[BajaFog]

Also look at Relion LiFePO4 - Amazing assortment of sizes/capacities to fit weird applications/places. Can be hooked up in parallel, have a good warranty - worth a look:
https://relionbattery.com/products/l...ional-vehicles

[TitanMike]

Originally Posted by JLeising

Not aware of anyone actually having a problem, but be aware that apparently the Mercedes “upfitter” guide limits current for an auxiliary battery to 40amps. As the Renogy dc-to-dc units draw 150% of the output current per their spec, that is why I chose the 20 amp version.

https://www.forestriverforums.com/fo...it-215973.html


FYI
Jim

I installed a shunt type digital meter inline with my Renogy 20 amp DC-DC charger's input. At a full 20 amp output the input current measures exactly 27 amp. Only 135% of the output. Close but still less than the Renogy spec.

One thing to take note of when adding load to a stock alternator, make sure to avoid excessive idling at times of high load. Cooling at low engine speeds can be problematic for alternators that have to rely on their own fans for cooling and the incoming cooling air behind the radiator is already hot. Not a big deal cruising down the highway but I wouldn't recommend using the engine for battery charging where it might be idling an hour or two without raising the hood for more cool air.

[Daebado]

Originally Posted by Daycruiser

Could they be fake, yep. Pretty elaborate for a scam, not that many scammers will spend the money or time to address all the details. When I emailed them about shipping they responded immediately, their English and grammar are spot on. If they're fake they did a great job of getting the right people to do their dirty work for them. We shall see.

So, did you get your batteries? Never heard anything back from you since last May and you were expecting them in June...

[Hclarkx]

Originally Posted by babock

Don't know why anyone would want to run a 24V system unless they have huge inverters running air conditioning.

I have the same question. If you must have 10 feet or more between batteries and the inverter, then smaller wire helps make 24V more attractive. And solar controllers can handle twice the Watts at 24V so maybe one solar controller instead of two in a large system; and the solar controller is slightly more efficient. But, you lose those benefits in the 24V - 12V conversion.

My son's system has 840 Ah of LiFePO4 (12 280 Ah cells), three 120 amp BMS, a 3500 Watt inverter, two 60 amp solar controllers (2000 Watts of panels), etc. The only extra bit was parallel 1/0 welding cable runs from the busbars to the inverter (2 x 170 amps, so 340 amp for each pair). It helps that the inverter is only a couple feet from the batteries.

My system is similar, 700 Ah of LiFePO4 battery, three 40 amp solar controllers (1800W solar), etc. 12V is working just fine.

[Hclarkx]

Originally Posted by TitanMike

If I was running A/C from my battery bank I think I'd not stop at 24 volts but rather make the jump to 48 volts.

Can you provide some background on this recommendation? Conventional A/C or mini split? A/C ratings? Battery size? What bottlenecks or costs that 24 or 48V addresses?

It's not uncommon to hear this recommendation, but I've never seen much discussion of the merits.

[Hclarkx]

Originally Posted by TitanMike

Hard to see how a split system is more efficient, at least mechanically, as on the rooftop units one motor does double duty. Both cool the condenser and push air through the evaporator. A split requires two motors.

As for more efficient compressors I would imagine that more efficient compressors are possible but don't fit the price point required for most RV manufacturers. My Chevy Volt has electric powered A/C but I'd hazard a guess that the compressor alone is as much as a Coleman, Dometic, or Furion rooftop unit complete.

Not saying the split can't work, just figure that there has to be a good reason the industry hasn't jumped on it.

Mini splits indeed aren't as efficient in an RV as they are in a home system because the use is somewhat different (though probably not so different for full timers). I.e., less use at very low outputs where the efficiency is very high. Using EER instead of SEER is probably more relevant for RV'ers in a mini split evaluation.

Yes, two motors .... both very efficient and running at much lower speeds and very low speeds much of the time. The motors are permanent magnet field so do not have as much copper resistive loss. And the mechanical losses saved by the low RPM are dramatic (includes motor and compressor). Mostly though, it's the ability to slow the motors when cooling demand is low.

In my case, half the BTU/Hr of my roof-top unit was used to cool down my roof along the air ducts. The mini split does not have this problem, though will mostly cool the room where the indoor unit is.

As for price point, 9k mini split systems suitable for RV use run from $600 to $1200 with price varying primarily with SEER rating. You'll need a bit more battery and solar (or more judicious A/C use) for a $600 unit though a more efficient unit might cost less than the incremental battery and solar. If one must have the unit professionally installed, double these prices. Though units now come plug and play for those with some mechanical skills and time.

As for why the manufacturers are not going this route .... I gather some are though I've not explored the options (they are probably not available in an RV that is appropriate for me ... a $40K fifth wheel). The biggest drawbacks have to be a place to put the outdoor unit and the greater installation labor in a competitive market. And the fact that only dry campers would want them. There's little point to efficiency if you are going to plug into a 50 amp outlet each night. Some of those users might appreciate the hugely lower noise level though.

DIY guys sometimes put the outdoor unit in a side storage compartment and I think the ones installed at the factory are like that. The outdoor units go on a rear bumper or tongue in the case of a trailer or 5th wheel. My son's conversion of a 93 Allegro has one outdoor unit up front where the generator used to be and one in a void alongside the diesel engine (that one is only used at night when not traveling).

I'd guess that as word gets around the demand for the high efficiency and low noise will grow and units specifically designed for RV and long haul truck use will emerge and cost will come down. There have been some compact outdoor units come and go. And one company is making DC powered units. It's a slow process. Heck, mini splits started in Japan over 30 years ago and have been in use in much of the world for many years (where energy tends to be more costly). The penetration in the USA is still small in spite of the fact that the higher cost has only a few year payback. And if one goes solar, a third or half the higher cost is covered by needing less solar. In my own home system, my heating and cooling cost were cut by 2/3 by a mini split retrofit.