question

You want Air Con to be running off of it so this indicates heat is a factor. Are the cells going to benefit form this cooling? If not and they are going to be in a hot environment then just do not use them. You do not want to over look thermal management with this chemistry especially with a lot of cells. If one cell goes into thermal runaway they all go like fire crackers.

@murphyslaw, this is definitely not a recommended -or supported- design. The Quattro programming interface and standard-range voltage requirements are exactly the same as a MultiPlus, so you're not gaining any flexibility by going to a Quattro over a Multi... and scavenged batteries are definitely not a supported power storage method in any Victron system. I understand that you're looking at their energy density and being impressed, but please understand and take into account that there is a vast array of things that can go horribly wrong in any scavenged battery setup, let alone a scavenged LTO setup... if anything, at least go with scavenged LFP cells that don't need liquid cooling and are highly unlikely to burst into flames that you can't put out if they get hot.

To be entirely honest, their hinky voltages should be the least of your concerns in trying to use these to power your system; their cooling requirements and their high fire risk should be the first considerations that point you away from using LTOs.

Can it be made to work? Yes, probably. But should it? No. And, too, being that it's an entirely unsupported configuration, I would effectively consider your Quattro's warranty to be null and void as soon as you hooked it up to scavenged cells of any kind, let alone LTOs like the Teslas.

Bottom line: Please think very long and hard before you attempt this, as any of us with experience will strongly advise against it.

I have two teslas in parallel in a mobile environment. The multi plus handles the voltage requirements easily The batteries can handle the discharge rate you're describing easily without heating up excessively do get easy start for your Ac's., Of course, you need to set up your own battery management system to back up the Victron products for low, high voltage, temp, and cell balancing, I can recommend where to get the teslas that are fully tested and rewired for cell balancing, etc. If you do go this way, Teslas are not drop-in solutions - nor do I think are Victron products - your gonna have to do your homework and I am a long way from being a pro on this stuff -I consider myself a total noob. That said I really like 18650 batteries been handling them for 7 years daily in other applications with individual discharge rates that our testlas will never experience in the application we are looking at here.

For starters... I am not dicing anyone's concerns regarding used batteries. I have seen the clips of Tesla fires and it's serious, but the energy density is beyond phenomenal and I believe worth the informed risk.

I just want to build the safest, most bullet-proof system I can. Weight is an issue and that's why I am passing on FLA and AGM. This level of storage would equal 28 12v Battle-borns at a cost of $28,000 and weigh 868 pounds. I can have my pick of 6 teslas, and test them myself for $5200 and the total weight is 360 pounds. Tesla's are the best bang for the buck...

I am looking at the Tenergy 5-1 to handle cell balancing. The batteries are going to be inside the coach to take advantage of the warmth of the Dickinson stove I am installing for cold weather.

I am planning to include a glycol reservoir to move 'cooling/warming' fluid, but I will have at least (4) teslas wired series-parallel, and possibly 6 teslas... depends on funds. That's a staggering 1400 ah at 24v... I can't imagine how I will ever go beyond 1C, so the cooling system I am already incorporating really is superfluous.

The Victron Smart MPPT Controllers have temp shutoff to prevent charging in the cold and I can't think of a situation where it would be too cold in the coach to charge the batteries while plugged into shore power.

I believe the Victron Equipment (low voltage/overcharging) will handle battery management and the Tenergy 5-1 will handle cell balancing.

I am also playing with an idea for an Arduino controlled relay switch to isolate the batteries as a backup based on high/low voltage and high/low temperature. Still hashing out the basics on that one, been too busy with other stuff.

As for Air Conditioning... the plan is to go North as it gets hot, but I want the option. I like options...

My current idea (subject to change at my whim) is to remove the rear AC from my coach and install a 220v mini-split on the rear of the coach with the head units in the living room and bedroom.

I am IMPRESSED with their energy efficiency and plan to run the unit using a Single-Phase 220 inverter solely for this purpose, and protect that circuit with a Victron battery protect.

I have considered just getting a 220v inverter and splitting the legs, but balancing the 120v out seems like a pain. The AC won't run often and having the Victron solely handle the 120v system seems like a righteous plan.

The 220v inverter (Off-Brand) need only operate when I run the big AC unit.

I might use the Victron 120v to power the remaining roof AC unit when traveling, for short periods and it will have a soft start. I know the mini-split will work great when parked, and I know the unit can handle significant jostling, in shipping... so long as it isn't running. I do not plan to torture-test my mini-split by running it why cruising down the road.

The ultimate goal, to become as energy independent as possible... I like long-term boondocking and want to extend that time to the extremes.

SO what the consensus? Quattro 48v or Multiplus 24v?

I have two Teslas in parallel in my RV using a Multiplus 24/3000 running a 24 volts system. The muliplus works fine in the voltage range I use 19 volts to 24.4 volts running a 48 volt (38 to 48.8 volts) system would be even better. I have run my AC 10 hours straight off the battery system and the battery does not even come close to hot. You will not void your multiplus warranty by using Teslas. That is clearly just BS. Even the owner of Victron has helped us Tesla uses by lowering the low voltage restart values in the programming of the multiplus.

I use a proper BMS system the Electrodacus SBMS0 and it controls balancing, under voltage, low temp and over temp, and over charge issues and is compatible with Victron equipment to send a high or low signal. For the size of your system i would recommend you use the REC-BMS as they can do 12 S in your 48 volt system and have a master and slave system.

I do use heated coolant to keep my system above 40 deg F for charging, but you dont need to cool the battery for the low draw use in a RV.

People saying Tesla batterys are unsafe is BS again as long as you use a proper BMS and do not over charge them. Even Lead Acid will catch fire of you over charge them and cook them. Believe me there are more Tesla batteries on the road and charging in peoples garrages than any LiFepo systems. Sure LiFepo have a better voltage range but they are heavier and cost more than the Tesla for RV use.

I know I am bringing up an old thread, but it references something I haven't been able to discern. Is there anyplace that lists the max draw one should pull from a Tesla pack based on ambient temp? Like if it is 100F outside and the batteries are using ambient air to cool, what would be the max draw before active cooling would need to take place?

I am planning on installing two Tesla modules between the rails under my RV. I will occasionally use them to run an AC at 1600W uptown 2000W. So, I expect a max C of around .2.

Thanks!