Magnum Energy ME & MS Series Battery Monitor Kit (ME-BMK)

Great item for monitoring you system. Goes well with other magnum products.

I installed this on a RV so my comments are specific to that application. I recently installed a residential refrigerator and now find myself using the inverter constantly when not "plugged in". Never really used the inverter much before but now find myself constantly concerned about my batteries and their level of charge. This is the solution, think "battery fuel gauge" with extras. Installation is straight forward with good instructions. Several items are not included and some have lowered their rating because of this. With each installation different I find that not reasonable. Plan your installation, the manual is available online but you also need to read your inverter manual to insure compatibility and understand how this works. Map your installation to calculate wire lengths needed. Additional items I needed to install this in an RV. Wire to make connections to both the positive and the negative battery terminals. Used 10 gauge because I had it on hand but 12 would work fine. Connectors for the wire and a "in line" fuse holder with 2 amp fuse. I used red wire and black wire to make it neat and easy for someone to understand if needed. You will need a battery cable with the appropriate ends to "insert" the shunt on the negative (ground) battery cable. Don't go cheap on this, buy a good copper cable the same size that is currently in use with the right sized ends installed. Good source here on Amazon. Lastly I recommend some plastic wire loom to protect all wires run including the twisted pair cable and communication cable. Most difficult part was running the communication cable from the inverter under the bed to the battery bank in the basement.

Create an isolated termination point and send as many negative connections to this baby as you can. It's good for up to 500amps

Very nice way to monitor batter power, as either a percentage of capacity or directly as amp-hours. I discovered, however, that I tend not to look at it... ever. Because the Magnum 2812 charger that I used it with does such a good job, that this is simply icing on the cake. Again, NOT their fault. If you're going to be doing a lot of boondocking, I can see where this will be a very important tool to watch conditions and know when either you have problems with your batteries or power consumption. But in "normal" (i.e., not boondocking much) use, it's probably overkill.

Instructions are pretty straight forward, more so when used in a Magnum Mini Panel, which already has the shunt. The problem here, more so for lithium batteries is inaccurate readings. When checked with several multimeters, the readings are off by .2 which is deadly for lithium batteries if you are using the inverters charger function. I called Magnum costumer service (this was in 2021) and they were quick to send a replacement. However, the new one had the same flaw. Which researching on forums, it seems like a common issue with the BMK. If you're not using the charger function, the issue is quite small as you take that difference into consideration. Charging parameters must be precise, and the unfortunately the BMK is not.

This unit is a must have with the current Magnum controller. Before all I could really see was the volts and AC flow at a very high level. With this kit, I am able to see all the current running in and out of the battery bank. The controller will give a basic % of battery charge for a quick look, but also break down the exact amount of amp hours being used, put back in and total amount since the start of the installation, to give you a better understanding how used the batteries are.

This was a nice addition to my MS2012 Inverter / Charger. It works in conjunction with the ME-RC50 or ME-ARC50 remote panels and displays the Rate of Charge (ROC) in either percent of capacity or amp-hours. After reading online RV forums talk about these ROC units I felt compelled to install one, and I am glad that I did because it gives a better understanding of the battery status.

I dont usually leave reviews on amazon, but I was incredibly disapointed with this product. This battery monitoring kit tries to be "smart" in detecting when the state of charge (SOC) is 100%, however if you are using solar, and start to get a small amount of charge in the morning, the low amps will cause it to think it is at the end of a charge cycle. SOC is reset to 100% even if though it may be 70-80% from overnight use. Cant be used to accurately show SOC in this scenario. I contacted Magnum support and got little help. Look to a different solution if you need accurate SOC info.