February 18, 2007 03:46
Last weekend, I fitted the new Nasa BM-1 battery monitor to High Spirit. My primary reason for doing this was that I've just had an eberspacher heating system fitted, and am worried about the potential current draw, and the risk of running my auxiliary batteries flat.
High Spirit's got a fairly standard (in the UK) Off - 1 - 2- 1&2 battery selector swith, and the BM1 was pretty easy to install. As I'm only monitoring one bank of batteries, I fitted the supplied shunt on the Negative return cable to the domestic battery. One minor annoyance was the my negative cable was two big to make decent contact with the nut and bolt terminal connector on the shunt. This was rectified by sandwiching it between two 3/4" washers on the bolt. In addition to this, there's four thin cables that need to be connected to either side of the shunt or battery, and lead back to the BM-1 display.
The BM-1 display itself is a standard size (as in Raymarine ST60 series et al) unit that was easily mounted to my existing chart table nav aids panel. Once connected to the battery, the BM-1 begins to calibrate itself. You need to manually configure it to the Amp Hours of the battery bank you're using in order to get meaningful information, but the instructions provided are excellent and this literally takes seconds.
The BM-1 provides a wealth of information about the current state of your domestic batteries, and the current demands on them. The default screen displays battery volts, % of charge remaining and amps being drawn.
![[Image: bm1.jpg]](http://www.nasamarine.com/Images/bm1.jpg)
The amp reading is particularly useful. I had great fun recreating the Ed Harris scene from Apollo 13, switching on the different electronics and electrical systems on the boat to see what the current draw was!
Of particular interest was the eberspacher heater (Gosport's cold in February) which, at one point during it's start up cycle, peaked at 10.4 Amps of load for a few seconds. However it fairly soon dropped down to a more conservative 1.6 amps.
Other information that can be displayed is similar to that you'd expect from a laptop's battery monitoring software; Time to charge / discharge (depending on whether you're charging the battery).
With more and more electronics on-board, the BM-1's particularly relevant. I've recently added quite a few bit of kit; AIS engine, SSB radio, NavTex receiver etc, and to know what these drain gives me the confidence to use them more. Definitely recommended.
I'll be publishing some ampage figures soon, particularly for running a MacBook under inverter.
ReeferJon
High Spirit's got a fairly standard (in the UK) Off - 1 - 2- 1&2 battery selector swith, and the BM1 was pretty easy to install. As I'm only monitoring one bank of batteries, I fitted the supplied shunt on the Negative return cable to the domestic battery. One minor annoyance was the my negative cable was two big to make decent contact with the nut and bolt terminal connector on the shunt. This was rectified by sandwiching it between two 3/4" washers on the bolt. In addition to this, there's four thin cables that need to be connected to either side of the shunt or battery, and lead back to the BM-1 display.
The BM-1 display itself is a standard size (as in Raymarine ST60 series et al) unit that was easily mounted to my existing chart table nav aids panel. Once connected to the battery, the BM-1 begins to calibrate itself. You need to manually configure it to the Amp Hours of the battery bank you're using in order to get meaningful information, but the instructions provided are excellent and this literally takes seconds.
The BM-1 provides a wealth of information about the current state of your domestic batteries, and the current demands on them. The default screen displays battery volts, % of charge remaining and amps being drawn.
The amp reading is particularly useful. I had great fun recreating the Ed Harris scene from Apollo 13, switching on the different electronics and electrical systems on the boat to see what the current draw was!
Of particular interest was the eberspacher heater (Gosport's cold in February) which, at one point during it's start up cycle, peaked at 10.4 Amps of load for a few seconds. However it fairly soon dropped down to a more conservative 1.6 amps.
Other information that can be displayed is similar to that you'd expect from a laptop's battery monitoring software; Time to charge / discharge (depending on whether you're charging the battery).
With more and more electronics on-board, the BM-1's particularly relevant. I've recently added quite a few bit of kit; AIS engine, SSB radio, NavTex receiver etc, and to know what these drain gives me the confidence to use them more. Definitely recommended.
I'll be publishing some ampage figures soon, particularly for running a MacBook under inverter.
ReeferJon