Hello.  I'm trying to find out if there is anyone out there who has done a test regarding MPP SOLAR and their battery voltage metering on the State of Charge of a battery.  There have been questions about this so I experimented (cheaply) to try to answer the question myself.  This video is my evidence regarding that question that many seem to pose on youtube or in other blogs.  Maybe I've just been lucky, but I don't see any discrepancies to the metering of their battery voltage.

 

 

1 hour ago, MetalFiber said:

I'm trying to find out if there is anyone out there who has done a test regarding MPP SOLAR and their battery voltage metering on the State of Charge of a battery.

Accuracy of the voltage measurement of the Axpert/MPP Solar equipment has never been questioned to my knowledge, and it is accurate to 1/10th of a volt which is more than adequate for its purpose (as is just about any digital voltmeter you can lay your hands on).

State of Charge measurement within the Axpert/MPP Solar (and most other similar equipment) is based on battery voltage which is a very poor method of ascertaining SOC and is highly inaccurate, bordering on useless.

Spend some time on the Forum and read up about Axpert inverters, Victron BMV-702 battery monitor (which will deliver accurate SOC) and ICC software which will help control your system using the SOC info delivered by the BMV. 

2 minutes ago, pilotfish said:

Accuracy of the voltage measurement

I also feel like I must add that an accurate voltage measurement in a busy system is just about impossible because of voltage drops across the various cables. Especially where you have external MPPTs, you will find that there is four voltages in the system 1) the one measured by the MPPT (almost always a couple hundred millivolts high), 2) the one measured by the inverter (almost always a couple of hundred millivolts low), 3) The voltage measured by the battery monitor/BMS (which may be delayed by some seconds for some setups), and 4) the actual battery voltage you measure with the DMM.

I discovered over time that a perfectly accurate measurement isn't a deal breaker, what matters most (where there are multiple chargers) is a loose agreement. It reminds me of some of my training back in the day in distributed systems, where it also turns out that it doesn't matter if all the nodes have accurate time compared to the wall clock, what matters is that they agree even if they are all equally wrong :-)

Thanks for all the comments.  I figured SOC is different than just battery voltage.  I've been studying up on Victron and other brands that offer a bit more when it comes to battery charging.  I find it funny that there are many things involved in solar when it come to PV, the inverting itself and batteries.  I think MPP SOLAR is ok.  I'm finding limitations when it comes to battery charging.  I put on an Epever as is was inexpensive for a 40amp charger and gave me more control over charging.  I'd love to have a Victron, but they're just a tad out of my price range just yet.  Again thanks for all the inputs.