Fifth Wheel - 1500W Panels - 5000W Inverter - 233Ah Tesla Battery

[ashelby]

I originally bought Will's book thinking I would build my system from it. While a great resource, I ended up basing my install mostly on Tom Morton's (of Morton's on the Move) setup but changed where needed to fit my needs.

We used this system as we traveled the country for about 2 years, 40,000 miles. Including one section where we boondocked for 30 days (see video below on that one).

All-in cost ran close to $6,000 with the inverter being the largest cost about $2,800 at the time.

This is my schematic... (PowerPoint screengrab)



According to Victron, the BP220 could potentially overheat in this setup due to reverse current flow while charging, but I have never had the BP220 even warm to the touch. There are some newer configuration suggestions on their site. But this has served us extremely well.

Here's the Install wrapup video:

And here's the boondocking video made possible with the solar setup. It would have been far tougher, doing it on a generator alone.

Let me know if you have any questions and I'll try to answer them.

 

[snoobler]

What BMS did you go with?

 

[ashelby]

What BMS did you go with?

No BMS.

I had a heating pad and relay to protect from freezing temps. Although we never saw less than 40 degrees, even in the winter we bounced from Florida to Texas and stayed warm enough to never worry about it.

Over voltage was protected by a voltage monitoring relay connected to the BP-65's remote port.

Under voltage was protected by the BP-220 and actually saved us a few times from draining the battery.

The 400 amp fuse also saved us several times from over current situations. The parks occasionally lose power while we're running both A/C units and when the Victron switches to battery automatically it's too much draw. Pop. I started with 10 spares and ended up buying 5 more along the way so far.

As far as balancing the six cells. We keep the charge between about 30 and 80 percent. After approximately 300-400 cycles, the cells were min-max difference of .08 volts. Very acceptable IMO.

I recently disconnected the battery and balanced it using the Tenergy 5 in 1. After 3 days it was balanced to .011. That's the best the do Tenergy can do it seems. Tried three times to balance further.

Overall extremely happy with it and the flexibility it provides while traveling, basically hands off.

 

[BiduleOhm]

No BMS.

No BMS with a Tesla battery is very dangerous... They use NMC chemistry which can go thermal runaway in some cases. Please reconsider your choice before you have to deal with a fire.

Really nice besides that

 

[snoobler]

I thought I'd let somebody else say it first, since I'm the doom and gloom NMC dick.

You've cheaped out on a $200 component putting your entire rig at risk.

If you have an active monitoring system and check it several times a day, you're probably fine. If not, I hope your insurance covers damage from an improperly installed power system.

 

[Ampster]

It usually takes charging abuse or physical abuse for a Tesla module to go into thermal runaway. There have been some examples posted here of over charging but no thermal runaway that i havecseen. Unlike LIPO that have been known to self combust when left fully charged. Nissan Leaf modules are the same chemistry but do not have the same individual cell fuses that Tesla modules have. No reports of fires from them that I am aware of. Several of us have used Nissan Leaf modules with only a puffy cell being the worst case.
I agree a BMS with good temperature sensing probes would add some sense of security.

 

[BiduleOhm]

There have been some examples posted here of over charging but no thermal runaway that i havecseen.

I can recall of one being very very close to it tho... found it: https://diysolarforum.com/threads/tesla-battery-charged-to-28-volts-popping-and-shorted-out.9740/

Also even if there's no fire there's the money loss; it make little sense to not protect thousands of battery with a few hundreds of BMS. It's like seatbelts in a car: you can see them as an expensive option or very cheap given the security they offer

 

[Ampster]

Yes, I remember that one. Clearly a case of overcharging. Not the explody thermal runaway that resulted in a fire. We will never how close that one came to a fire or whether the popping was the fuses doing their job or the cells popping their tops.
Yes a BMS would have protected that one. Since I have always used a BMS I am not arguing against a BMS. I was objecting to the Fear, Uncertainty and Doubt (FUD) expressed earlier. I have said the same thing about LIPO and got called a troll as a result. Lipos have none of the protective devices that exist in a Tesla module.

 

[BiduleOhm]

Well it's not really FUD where there's significant chances it can happen.

No that's just my advice, everyone can do what he wants of course, but I wanted to mention it as it was not yet and the OP needed to know the risks before chosing BMS/no BMS

 

[snoobler]

This Tesla battery had a very robust BMS:

Remember... these batteries come from salvage yards.

 

[Ampster]

This Tesla battery had a very robust BMS:

So that nobody gets the wrong Idea, a BMS cannot always prevent a fire and and it can never put out a fire.

 

[Ampster]

And here are a couple of modules that were overcharged. I think this is one may give the readers some examples of the popping explody things that these can do.

 

[snoobler]

It was more intended to illustrate the damage potential. These batteries come from salvage yards. The potential for defects exist as does damage from whatever happened to put it in the salvage yard.

I have 39kWh of NMC cells, so I'm on board. I even ran a 7S 24V configuration w/o BMS, but that was only after testing all 84 cells for capacity and IR, top balanced and had 4A active balancers installed.

I'm not going to trust them without a BMS installed to ensure things stay where they're supposed to.

 

[ashelby]

I'm not sure what all the fuss is about.

I explained that I had covered all the basics of a BMS through alternative relays and temp monitors.

This Tesla battery was protected from under-temp, over/under volt, and over current. What more could a few hundred dollars do?

Maybe keep the cells more balanced... But after about 10 months, the cells were about .1 (min-max) out of balance. And I restricted charging to 80%, so no way a cell could get over-charged.

 

[snoobler]

The fact that you think 0.1V is no big deal just makes the point.

 

[HRTKD]

@ashelby, how large is your generator and how many amps does the starter pull? The reason I'm asking is that I kept a FLA battery separate for starting the generator. It wasn't clear how many amps the starter would pull.

 

[ashelby]

@HRTKD We only use a small Generac 2200 peak, 17000 continuous generator. It's a pull-start.

Merging that with the battery through the Quattro inverter powers anything we throw at the system. Except 2 A/C units running.

Once the generator is running, it takes about 15-20 seconds for the Quattro to start pulling from it and then deliver that power to the A/C system or begin charging the battery. Very smart system and I'm really happy with it.