Has anyone used a Victron SmartShunt IP65 500A on a normal 12V car starter battery?
My battery is 70 Ah, 700 CCA. I would like to monitor the battery’s voltage, current consumption, charging, and standby drain over time.
I understand that the SmartShunt is commonly used for solar, RV, marine and auxiliary batteries, so I am particularly interested in whether it is suitable for a vehicle starter battery, where there is a very high current for a few seconds during engine cranking.
My main questions are:
Is the 500A model suitable for this application?
How does it handle the short high-current pulse during engine starting?
Has anyone here installed one in a car and can share their experience?
It’ll most likely be fine, but depends on the lock-rotor startup current of your starter; some starters pull more than others. Generally speaking it’d be rare for an average automotive starter to pull more than 500A even from lock-rotor, so good chance it’ll be fine. If in doubt, get yourself a good multimeter that’s capable of measuring inrush/lock-rotor startup currents and check for yourself, then select the appropriately-rated shunt based on that measurement!
I will say that I’d be more concerned, if it’s a modern car, with how you’re going to set things up; modern cars often have their ECU monitoring the battery state, temperature, and charge current, usually through a current sensor on the battery negative terminal clamp, and you would need to move that to be able to install a shunt. The SmartShunt must be the only thing connected to the negative terminal of the battery being monitored, without exception, so any existing negative connections on your battery must be moved to the other side of the SmartShunt. This could, depending on your setup, cause other unforeseen issues with your onboard electronics/ECU monitoring/smart alternator operation (if equipped) and etc.
Obviously if we’re just talking about a 1977 Chevy Caprice, that’s not going to be a concern, but if we’re talking about a modern vehicle, proceed with caution after acquiring a full understanding of your vehicle’s onboard systems or consult a reputable and experienced automotive technician before you necessarily start fiddling with things.
Thank you for the information! Yeah, I was thinking the same, I would expect 500A to probably be fine. I assume the 700 CCA is basically the maximum current the battery is rated to deliver for starting, but I don’t think my car’s starter actually draws that much.
My car does have a very sensitive battery monitoring system and a smart alternator. But I’m not quite sure why adding the SmartShunt would be a problem. My goal is actually to have an independent way of monitoring the battery, since I cannot access or see all the information that the car’s own battery monitoring system is seeing.
As long as I install the SmartShunt between the battery and the car’s existing battery monitoring sensor, wouldn’t the SmartShunt simply measure the current going in and out of the battery while the car’s system continues to do its own monitoring? Wouldn’t both systems basically just be measuring the same battery independently?
Is there something I’m missing about how the OEM battery monitoring system could be affected?
I don’t know your particular car’s OEM battery monitoring system, so I don’t know, and thus advise caution.
If it’s monitoring temperature, you’ll be changing that datapoint by moving the point of connection; you’ll also be changing the resistance in the circuit, both because of adding contact points as well as because the SmartShunt is, quite literally, a resistor of known value which is how the shunt gathers its measurements.
Both of those factors, and any others I haven’t thought of, may be non-issues at all, or they could throw CELs or error codes or cause other issues within the vehicle… so, again I’ll just say proceed with caution after acquiring a full understanding of your vehicle’s onboard systems.