mikejkay Posted February 2, 2016 Share Posted February 2, 2016 Has anybody used this device to monitor both the starter and habitation batteries. I have seen a circuit diagram on NASA's website which shows this arrangement but there is no indication as to how you switch between measuring individual batteries. Link to comment Share on other sites More sharing options...
mikejkay Posted February 2, 2016 Author Share Posted February 2, 2016 Just found the answer: Press the V&A button a second time and the display will show the starter battery voltage and current. The manual states " when displaying the starter battery’s voltage, the instrument continues to monitor all aspects of the domestic battery" which would suggest that ampere hours is not available for the starter battery. Anybody got any real world experience? I thought that the BM1 was quite popular. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted February 3, 2016 Share Posted February 3, 2016 Not sure how popular the NASA monitor is, but it’s evident that some forum members have hands-on experience of it. (I’m sure your assumption is correct that the BM1 is designed to check just the voltage of the starter-battery.) Link to comment Share on other sites More sharing options...
Tracker Posted February 3, 2016 Share Posted February 3, 2016 Back in the 80s I've had experience on inshore sea fishing boats of NASA marine instruments, depth sounder, vhf radio, navigation and it was all well designed, easy to use and reliable, if pricey, kit that did exactly what they said it would. Support and repair was also reputedly good back then although we never had need of it and I have no recent experience of NASA kit. Maybe have a look on the yachting or boating forums for feedback as that was/is their primary market? Link to comment Share on other sites More sharing options...
Robbo Posted February 3, 2016 Share Posted February 3, 2016 I have a NASA BM1 Compact fitted to monitor the leisure battery. The manual for the "compact" version only makes reference to monitoring the leisure batteries. In the Q&A section it states that it is only designed to monitor one battery bank. Maybe the standard BM1 can monitor both leisure and starter batteries - I don't know. I purchased the Compact version because it fitted better into the space available for mounting. Also, I only wanted to monitor the leisure battery anyway. I've found it to be a very useful tool to monitor charging and discharge currents and of course an accurate display of the battery voltage. Link to comment Share on other sites More sharing options...
tonyg3nwl Posted February 3, 2016 Share Posted February 3, 2016 Hi, cant resist this. is it rocket science? Tonyg3nwl. Link to comment Share on other sites More sharing options...
Tracker Posted February 3, 2016 Share Posted February 3, 2016 tonyg3nwl - 2016-02-03 7:23 PM Hi, cant resist this. is it rocket science? Tonyg3nwl. Nah - course not - it's electronics - rocket science is about lettuces. Link to comment Share on other sites More sharing options...
camoyboy Posted February 3, 2016 Share Posted February 3, 2016 Just fitted a BM1 to our new Carthago. The starter battery is monitored for volts only, accessed by pressing the VA button. This feature is not on the compact models. The monitor is reasonably straightforward to fit, installing a shunt on the negative side of the leisure battery/batteries and running a cable to the monitor from the shunt. The cable for the van battery is not included, but everything else is. The cable for the van battery runs from the monitor direct to the battery and requires a 1 amp fuse. The monitor is very accurate when it is set up, showing both charge and discharge amps, the amount of time left for the battery to flatten at the current discharge rate, or time to charge up if recharging. There is also a percentage display, and a record of amps used over a period of time. Did have a minor issue when I first installed mine with the fuseholder supplied, but quickly sorted with a better quality fuseholder. Expensive but very useful in understanding how much power each item requires to run, and when the batteries are fully recharged. Colin Link to comment Share on other sites More sharing options...
mikejkay Posted February 4, 2016 Author Share Posted February 4, 2016 Other battery monitors include the Votronic LCD Battery Computer 100S/200S and the Victron Battery Display Monitor System BMV-600S/700S. Quite a bit more expensive but appear to be a bit more sophisticated. Schaudt do the LT 320 Solar Display Panel which seems to be less usefull. Any ideas/recommendations/comments. This is to monitor the batteries and a 150w solar panel on a new Hymer. The Hymer panel seems to be woefully inadequate. P.S. I am an unashamed "Wild Camper" a.k.a. a leech (by some). Three monthe in Norway in 2015 and didn't stop in a campsite or use an EHU once :D . Link to comment Share on other sites More sharing options...
veletron Posted February 5, 2016 Share Posted February 5, 2016 We hardly never stop on sites either. I will use them, but my max spend per person is £7/night for which I only expect a toilet and somewhere safe to abandon the van for the day. This is more practical when I am not on my own because the budget is then £14/night! Generally I consider sites to be a rip-off. We joined the caravan club to get access to the CL's which we have used a few times and find them to be good value, would not dream of coughing up £20-£30/night for a standard caravan club site though - different if you are a family of course. As for the BM1, I fitted one in my 'new' van. They wont monitor the current to/from the starter battery, only the voltage. The BM1 works out the leisure battery state of charge based on both the voltage, the capacity you set and the charge/discharge current. When you think about it, having it monitor the current for the starter battery would require a shunt capable of ~300A peak current for a cold start! The built in panel in my van reports 12.4V when the real voltage is 12.8V thats the difference between 50% SOC and 100% SOC eg its useless! Nigel Link to comment Share on other sites More sharing options...
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