Quote:
Originally Posted by eggman1950
...I actually want to know the status of my batteries and their condition and percent of charge. We don't do a lot of boondocking but want to be able to and if so will need to know battery status. Installation instructions seem straight forward and I'm ready to pull the trigger on purchase and install. Anyone put one of these in and if so do you have any tips, traps or suggestions for my coach or in general?.
|
eggman - We are in the process of upgrading our 2015 DSDP to include the BMK and ARC-50, along with new Lifeline batteries. I'm no expert here, but have condensed what others have recommended.
We chose to add the BMK for the same reason you reference (and twinboat's perspective) - which is to accurately monitor our battery bank's State Of Charge. The battery gurus out there recommend managing your batteries by SOC, rather than VDC, because it's not practical to disconnect batteries for 1+ hour to measure their resting voltage. The BMK measures the amount of current out of, and back into, the battery bank, and manages accordingly.
So here's where we're at. We replaced our 8 Discover AGM batteries, installed but have not connected the BMK, and replaced and reset most options on the new ARC-50 monitor. Our Discover AGM batteries failed after just 20 months. (topic of another thread). We purchased 8 new Lifeline GPL-6CT batteries (1200 AH total), and installed them Sunday (with help from NormMac!). Norm and I also installed the BMK in the back of the battery bay, and reconfigured the battery wiring. Owing thanks to CapuTech, we optimized the battery wiring configuration, as Newmar's wiring - while not
wrong - was not optimized. In fact, it's downright inefficient.
To your questions, here is the logic and procedure we followed. I'm assuming you have the MS2812 inverter, all electric, 8 batteries, etc. If not, your config may vary...
1. Agree with your decision to add BMK, and manage battery charging via SOC.
2. We added the ARC-50 to improve monitoring / control over charging and the AGS. This was highly recommended by both Magnum and CapuTech.
3. While not directly related to your quest, I'd recommend a battery run-down test. That is, measure voltages on each battery, pull your shore power, measure each battery again, and every 30 minutes for a few hours. This should give you an idea of how long they'll last when boondocking, and identify any bad batteries. This is how we discovered we only had 3 hours of battery life and found 2 failing Discover AGM batteries. IF you find any batteries that decline VDC faster than the others - take action
now. If you exceed the 12 month warranty period - expect no relief from Discover. And, they'll recommend you purchase 8 new batteries. Yes.
4. Label all your battery cables and take "before" photos.
5. Pull all batteries out of the tray, to give you less restrictive access to the back of the battery bay.
6. Install the BMK on the vertical support rail at the back of the battery bay.
7. Connect the BMK per Magnum's recommendation.
8. (disclaimer - this is how WE wired our battery bank. Seek professional guidance if you decide to follow this).
a. Wire a single very large 4/0 cable from lower left negative post of battery bank to the battery side of the BMK shunt.
b. Wire all 3 large negative cables to the load side of the BMK shunt (Frame ground, Inverter ground, House DC ground)
- purchase a longer bolt for this side of the shunt. Too many lugs make the connection very hard with the included bolt. CapuTech recommended a bronze 1" x 3/8" - 16 UNC threaded bolt - don't mix dissimilar metals).
c. Wire all 3 large positive cables to the upper right positive post of the battery bank. (House DC+, Inverter +, and BIRD).
d. Wire the BMK's power + wire to the upper right positive post, and BMK's ground wire to the lower right negative post (effectively across a single 12 volt battery - the BMK draws very little power).
- you'll need to provide this power / ground cable and 3 amp in-line fuse, to power the BMK - it's not included in the BMK kit.
9. Replace the RC-50 with the ARC-50 - up to you. There are benefits and more granular / accurate battery management. It's not cheap ($240), but neither were the Lifelines.
10. Purchase a phone cable splitter with a short cable. There's a splitter included with the BMK, but there's no room on the Magnum MS2812 network port to use the splitter. You need a splitter with a short single cable - sort of a Y cable. Short RJ14 cable plugs into network port on inverter, and other end gives you 2 sockets - for the AGS and BMK inputs. (there's no room at the network port, because Newmar installs the Precision Circuits AC power management device, which shares the same "monitor port" as the RC-50. Hence, it's plugged into a splitter on the Monitor port, preventing another splitter on the network port.)
11. Before plugging in the BMK, fully charge your battery bank.
12. Plug in BMK to inverter and reconfigure the (A)RC-50. I called Magnum for guidance on settings, before and after the installation. This is how you optimize battery management, using SOC for charging and AGS parameters.
This got to be a lot more long-winded than I expected, but the devil is always in the details. If I left anything out or unclear - let me know. Again - this is how we solved our battery configuration issue, and many thanks to NormMac for his hands on assistance, and CapuTech for technical guidance.
Oh yeah - how does it work? Don't know! Haven't pulled shore power yet. Waiting to connect and optimize the BMK.
Attached battery wiring diagram courtesy of CapuTech.