Question about using Current Shunt on battery

[Salts]

I'm going to be hooking up a Rec-BMS and ordered a 50mv shunt from them.
My inverter can also use a shunt to measure current draw.

Can I hook both to the same shunt? The way I figure it, each device is just basically using an internal meter to measure the voltage differential. So would hooking two devices up to the same shunt cause a problem?

[Ampster]

I'm going to be hooking up a Rec-BMS and ordered a 50mv shunt from them.
My inverter can also use a shunt to measure current draw.

Can I hook both to the same shunt? The way I figure it, each device is just basically using an internal meter to measure the voltage differential. So would hooking two devices up to the same shunt cause a problem?

It is worth a try. I would think those two devices would need to be isolated enough that you don't get transient currents that would screw up the measurments of the shunt. You could probably check that with a VOM.

Somewhat related in a tangental way, I had problems with my Outback Radian inverter putting out EMFs on the DC side such that the shunt on my BMS wouldn't register Amperage.That was years ago and I couldn't use the BMS for SOC. My Outback Skybox is better and the same BMS is giving me good SOC measurements today.

[Salts]

It is worth a try. I would think those two devices would need to be isolated enough that you don't get transient currents that would screw up the measurments of the shunt. You could probably check that with a VOM.

Somewhat related in a tangental way, I had problems with my Outback Radian inverter putting out EMFs on the DC side such that the shunt on my BMS wouldn't register Amperage.That was years ago and I couldn't use the BMS for SOC. My Outback Skybox is better and the same BMS is giving me good SOC measurements today.

Interesting comments on the Radian. Did you ever try putting some ferrite rings on your lines to see if it would quiet the EMF?

I'm not sure I want to try hooking two devices up to a single shunt without knowing what's going to happen. Sunny Island inverters are not cheap, although I'm not sure what could possibly go wrong other than an incorrect reading. I don't like guessing when it involves $10K worth of hardware and a lithium battery just looking for an excuse to go all 4th of July on me.

Maybe I'll fire off another email to the Rec-BMS guys and one to SMA support and see what they have to say.

[littleharbor]

. Sunny Island inverters are not cheap,

Historically Sunny Island Inverters have been very expensive. Not sure what's going on with them but lately I've seen them selling for 1/4 to 1/3 of their regular prices. Right now they're going for as low as $1200.00 for new SI6048-US-10 models.

[Salts]

Historically Sunny Island Inverters have been very expensive. Not sure what's going on with them but lately I've seen them selling for 1/4 to 1/3 of their regular prices. Right now they're going for as low as $1200.00 for new SI6048-US-10 models.

Ya, I got mine for $1100 each for two of them.. its a one time thing on ebay, and when they're gone, the replacement cost will be $4k each or more.

[Paul Land]

what is Mv of the 1st shunt

[Salts]

what is Mv of the 1st shunt

Rec-BMS shunts are 50mv. The Sunny Island can accept 50mv or 60mv.

[Aurimas]

Hi everyone, maybe someone know why on fronius inverter display the moment power it shows with the minus simbol for example. - 30W