homeadrift avatar image
homeadrift asked

Limit Battery Draw - Keep Blowing 400 Amp Fuses

I have an Quattro 24/5000/100 hooked up to shore power. Absolutely love it so far.

Also have a Tesla Model S bat, 233 Ah.

I have been testing the system, and can't seem to find an option to limit the draw off the battery when using only the battery.

As I start adding loads, air conditioner #1, then #2, then microwave, pop goes the fuse at about 200 amps. We have blown 4 of these already, 1 in testing, 3 in real world use.

From what I have found, the Tesla battery is rated at around 200 amps without cooling and that's more than I ever want it to draw.

Question: is there a way to tell the Quattro to just shut down if more than 200 amps, or say 4000 watts are being drawn off the battery?

I would rather that happen, then the fuse blowing every time the wife or kids turn on a blower dryer without thinking, while off grid.

Also using the Venus GX, 220A bat protect, 65A bat protect, and MPPT 50/100 with 1500 watts of solar panels.

Thanks for any help!

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3 Answers
boekel avatar image
boekel answered ·

No you can't really, except from Guy's advice to put a breaker on the output side of the inverter (but that won't help you when on shore power)

Also the inverter can be overloaded quite a bit, a 300-350A draw is quite normal for these units.

The problem:

-your battery is too small
-your battery will need active cooling at 200A draw, even a 100A draw will warm up the battery, the inside more than the outside cells, a 'full pull' at 100A might already damage the battery, and can set it on fire!

I'd use at least 3, preferably 4 modules, think about active cooling, etc.

What BMS are you using?

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homeadrift avatar image homeadrift commented ·

Bummer, monitoring watts, and programming something based on it seems pretty straight forward... and intuitive. Of course, that's from a users perspective and not an engineer's.

I will likely get another Tesla Model S battery for 466 Ah total at 24V.

Also, I did use the recommended 55 m2 cross section welding wire (1/0 gauge - times two) across all connections. And after the fuses were blown, they were all pretty warm to the touch.

Can't imagine pulling 350 amps continuously and not smoking a cable. 200 Amps at 24 is 4,800 watts, we would never need more than that continuously in our camper.

But, there is the occasional kid that starts the microwave while both A/C's are running and boom, fuse blown. I'll just order a bunch, only $10 for 3 on A-Z.

Putting the second A/C on AC out 2 isn't feasible, then we wouldn't be able to use it period when off shore power. I want the option of turning either A/C on.

No BMS yet. Most reports say a simple RC style lithium balancer will do the trick on these. My cells haven't been off by more than .03 yet.

Thanks for the info and response.

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wkirby avatar image
wkirby answered ·

Are you blowing 400A fuses or 200A fuses? The title and body of your message conflict.
A 200A fuse is a bit low for that Quattro.Nominally, it can draw more than 200A continuously. The types of loads that you speak of are notorious for having high inrush currents which will easily translate to current way in excess of 200A on the DC side.
I'd be aiming for at least a 300A fuse with appropriate DC cabling on the DC side.

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homeadrift avatar image homeadrift commented ·

Thanks for the response.

Yes, I have the recommended 400A ANL fuses. But like you said, the inrush currents are what's blowing it. Usually within a couple seconds of turning on a high power device if there is already a significant load.

We had a real world power outage yesterday, normal electronics running plus two A/C's. UPS was enabled. So, of course... fuse blown when it tried to pull the load off the battery.

My question is, can the Quattro limit the amount of Amps or Watts drawn from the battery? Even if it just shuts down due to over current, I would be happy with that rather than blowing fuses.

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Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

The best and easiest way is to put a small AC circuit breaker on the output.

Easy to reset. And free.

16A @ 230V should trip before the DC fuse.

The Quattro is designed to run the loads.

It may be possible to get more elaborate and connect high power load circuits to ACout2 and then program it to open the relay and disconnect that when load exceeds 3000W, and have that conditional on AC input.

But I’d just use the circuit breaker.

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