Hi There. So my set up is 2x214w solar panels, LiFePO4 house battery, Ford Transit dual AGM starter batteries. Multiplus 2kVA 120v, Lynx Distributor, Orion Tr DC/DC, BVM-712 Smart Shunt, SmartSolar 100/30 and SmartSolar 75/10.
I want to maintain the starter AGM battery when parked for an extended period of time with my solar panels. I also want to be able maintain the House lithium battery with solar (and not connected to shore power) while parked in storage as well. I have both solar panels (parallel) connected to both SmartSolar MPPTs. The 100/30 connected to the Lithium and the 75/10 connected to the starter AGM. I also have a 4 way isolating switch to connect the 75/10, or connect the Orion, or connect them both, or disconnect them both to the AGM. The idea here was to have different charging profiles (solar) for the different battery chemistries. So when in storage I have the switch connecting the 75/10 to the AGM and the 100/30 always to the Lithium.
The problem I’m having is that the two controllers aren’t working simultaneously to maintain their respective batteries from the solar panels. When I have the 75/10 on, the 100/30 turns off. When I turn off the 70/10, only then the 100/30 turns on and charges the Lithium.
Is there any way to charge each battery with different controllers from the same panels?
Also is there any downside to having the 75/10 and the Orion switched together while driving and using the alternator?
Also the BVM712 has two monitor inputs, one for the Lithium, and one for the AGM. But only the Lithium is showing a read out. How do I add the second AGM read out?
Wow, you have some unconventional stuff going on there to say the least. First off, if I am understanding correctly, you can not have two charge controllers on the same array. They will almost definitely interfere with each other. There is no way to make them do what you are attempting. They are not designed for that purpose. Essentially the MPPT technology is watching(tracking) for the maximum power point. Now they are both tracking and interfering with one another. You will likely find someone on this forum explain this much more comprehensively if you want.
My recommendation would be to simplify this system by installing the components the way the were designed.
One MPPT charging one battery bank. If you want you could install a small solar panel to just charge your starting battery using the 75/10.
Abandon the isolating switch and connect the 100/30 MPPT and the Orion properly to your house battery bank.
To maintain your starting battery while in storage(I assume your solar is working) you could use Victron Bluesmart charger.They come in pretty small amp outputs very affordably and can be set to AGM chemistry. Blue Smart IP65 Charger | Victron Energy
You should not do this without setting up master/slave and networking them. The MPPT power search routine in one will adversely affect the performance of the other device. The 428W of solar will give you ~35A @ 12v, 31A @ 13.8V. The simplest way to set this up would be to just use the 100/30 charger to charge the house bank, and then to use a dc/dc converter or a simple AC charger from the inverter to keep the starter battery charged. at 12V, the Lithium and lead acid voltages are sufficiently similar that even an automatic charge relay could be used. A DC/Dc converter could also be used for charging the house battery from the engine.
With the BMV, the 2nd battery should show up in the Auxiliary battery voltage, but may need to be enabled.
I forgot to mention the Lynx distributor… but not important. Thanks for the feedback. Having separate panels for each controller isn’t ideal. So there is no way to charge two separate batteries with different profiles and one solar array? I may be overthinking it but the isolator switch does allow me to control the solar charging of the starter AGM vs the House. Just not concurrently. It may be unconventional, but I can still use shore power to charge the Lithium House with the Multiplus, and the solar to maintain the AGM Starter. I don’t feel way out in left field, but here I am.
ACR? Acronym for…? I would have liked to use the trickle charge from the Multiplus, but you need shore power or inverter, and the profile isn’t configurable (maybe doesn’t matter that much?) Maybe there is a 12v to 12v charger not Victron that wouldn’t interfere on the array. I’m not sure I’m brave enough to find out…
Automatic Charge Relay. This is standard in the marine and RV industry for bridging 2 batteries, once the charge voltage on either gets to a pre set level.
Trickle charge output from the Multi: you could use that, but ground wiring (-ve side) is then important - both batteries must share common negative.
DC/DC converters as chargers won’t interfere with the solar array and are also very common in the Marine & RV industry. Victron have two publications Energy unlimited, and wiring unlimited with lots of common examples. https://www.victronenergy.com/blog/2019/09/03/wiring-unlimited/ https://www.victronenergy.com/blog/2019/09/03/wiring-unlimited/
Looks like I have a viable use case for those enterprising engineers. I’ll only take a small percentage… just get in touch. lol. Also minutia, maybe charging profiles are just a way to eek out the best case scenario for each battery. Whats a couple of volts or a year between friends. Ok, no more IPAs tonight.
I wonder if you could use a Cyrix combiner installed backwards here. A little unconventional but seems like it could work. It should allow the starting batteries to be charged off the house batteries when they are at a charging voltage. Also, the Precision Circuits LI BIM allows the house bank to charge the starting batteries but would take the place of the Orion.
So this is the first really sunny day since I’ve been monitoring and they’re both working charging their respective batteries. I checked a couple of hours ago and both controllers were charging. I checked again just recently. Both batteries were fully charged and the chargers were both in float mode. Yesterday the 100/30 said that there wasn’t enough power in the (i) information dialogue, so wasn’t charging. Only the 75/10 was charging at a small amperage. But it was cloudy. I assumed that the 100/30 wasn’t working, but maybe it wasn’t getting enough juice. Each controller is programed to the battery manufacturer’s recommendation and seems to be maintaining, provided there’s enough sun.