I am switching out lead acid for lithium in my truck camper, I have all Victron products: SmartSolar MPPT 100/15, battery monitor BMV-702 and an Orion-Tr Smart Isolated DC-DC charger all going into two new parallel Lipo 100ah batteries with a 200 watt PV panel, system is 12 v. (any problems so far?)
The DC-DC charger is stumping me. In reading the manual and watching the videos I don’t see dual charging discussed. Obviously if I am sitting still with the engine off I am charging via solar, if I am driving at night I am just charging from the car alternator. But if I am driving in the day I am charging with both alternator and PV.
This seems problematic, is it? Does the system just shove electrons into it from both sources and stop when full? Can I “overcharge” the batteries? Does it need to have a specific setting with this setup? Are they going to war with each other?
If you see something -like I am making a huge mistake- then say something!
I will only endeavor to give you the simplest answer I can:
In a simple DC system the greatest relative voltage 'wins’ (provides charge). If one DC supply system is producing 12.8 volts of output/input and is ‘competing’ with another DC supply system producing 13.1 volts of output/input - well, the higher will win the charging position in the system. In a multiple DC input/output scenario where the voltage output/input is synchronized or adjusted to the same voltage from each of the DC units - in theory and in a perfect world - they would each contribute current to the system (limited to their capabilities) on an equal basis.
A charging system/charger becomes the referee regarding competing multiple voltage inputs.
If you are using any device labeled as a CHARGER or MULTIPLE CHARGERS from different sources - in theory and practice - a charger will not ‘overcharge’ a battery based on the built-in or selected charger settings (Lead acid chemistry, AGM and the like). A charger generally ,by design, will stop charging once a prescribed maximum voltage level is reached in the battery over a given amount of time thus protecting the battery from overcharge. There are caveats to this but I am trying to keep this as simple as possible.
Additionally, if you are using a Lithium chemistry battery system as stated in your post, the onboard or outboard BMS will generally be the gatekeeper and final arbitrator of how and when the battery is charged and will generally be programmed to disable charging once reaching the programmed charge limit. Any surplus voltage/current supplied to the DC system by your alternator, inverter charger or PV(MPPT Controller) system will be available to any of your active DC loads but battery charging would be disabled by the BMS. You will need to set your charge settings on all charging sources (MPPT 100/15 and the Orion-Tr Smart Charger) for charging Lithium chemistries and make any adjustments to charge voltages as recommended by the battery manufacturer.
Have a look at setting up a VE.Smart Network with Bluetooth. The MPPT and Orion will use the voltage of the BMV to set their charging algorithm. There will be no fighting they will be a slave to the BMV.
I thought the 702 could they have the network setup instructions in the manual. You are correct about the Tr Smart. I should know I have one installed on my boat. There is nothing smart about it.
Check Justin’s comment, the Tr smart DC-DC is very much standalone. It does not communicate with anything. It might be worth having a look at setting up a network with BMV-702. Here is the manual.
Well the BMV-702 doesn’t have bluetooth at all, is the problem there; odd the manual there lists it as an option without mentioning that additional equipment would be required. With an added Ve.Direct Bluetooth Dongle I believe it can work, though.
And “Smart”, in this context, just means it has a bluetooth module, which the Orion-Tr Smart does have.
I have not used the BMV-702, but I know from reading that it has a relay. You could use the SOC function to turn on the remote of the DC-DC charger. This will allow you to charge the battery from the alternator when the SOC is low, allowing you to get as much from solar production until it drops. You can also use the relay to stop the DC-DC charger when the SOC is, say 90% and let the solar finish it off. You only have problems charging from 2 different charge sources that are not communicating when the battery is near full.
