A very simple question I have smart solar charger to charge the leisure battery of my campervan. I want to add an Orion DC-DC to also charge from the alternator. If I connecto both outputs directly to the battery when driving potentially I could have DC-DC converter and smart solar charging trying to charge rthe battert at the same time. Do I need to disable the smart solar output to prevent any issue when driving .
I’m a qulaified electrical engineer… so I do know hwat I’ doing. thanks
They will work together OK. Once the battery reaches absorption you will find one cuts back charging first and goes to float first. Some people deliberately set the DC to DC charger voltages 0.05-0.10V lower to give priority to solar.
Are Solar Inputs (Smart MPPT) and Input from Alternator, (Orion), Prioritized, if at all? Are these these inputs “managed?”, eg by CerboGX or VE.Bus BMS V2? How is it a Smart MPPT does not see the Orion input as, say, a fully charged battery, when it is the alternator input, and vice versa?
Chargers work off the voltage going into the battery, the absorption voltage which will be set at something like 14.2V. When the battery is quite empty the charger will be outputting it’s maximumoutput Amps and the voltage will remain below 14.2V. As the battery gets fuller, the voltage will increase until it reaches 14.2V, at which point it is nearly full. As the last of the battery fills up, the charger reduces the Amps going in to maintain 14.2V. If your MPPT is charging and the voltage is below 14.2V then the battery is not full so it can take more current when you start the engine. If the voltage then reaches 14.2V then one or both chargers will start to reduce current, both under voltage control and one will tend to reduce first based on small differences in wiring and accuracyof voltage measurement. With a VE bus BMS there is no prioritisation, the chargers follow their own settings. One way to get prioritisation is to set the MPPT to say 14.3V and the Orion to 14.2V, so when the battery gets to 14.2V the Orion reduces charge first.
Thank you for the reply.
Please see below two attachments, and I am only using these as examples of Orion and MPPT wiring. The first attachment shows the Orion and MPPT output leads joining together at a distribution bar.
The second attachment also shows the Orion and MPPT output leads joining together at a distribution bar, and also with the MPPT having a VE Direct Lead to the Cerbo GX. What does the connection to the Cerbo GX do please?
The first schematic shows a simple system where the chargers are completely independent of each other and there is no control from the battery so the chargers follow their own charge settings as I have described above. The small BMS just shuts down the chargers and inverter via the remote terminals if charging is not allowed.
The second schematic shows a more complex system with a BMS with more features. In this diagram the older Orion chargers are shown which do not communicate with a Cerbo GX. Therefore, in this case, the BMS still has to stop the Orions through the remote terminals. If a newer Orion XS was used then this would be connected to the Cerbo GX by VE Direct cable as is the MPPT. You will note that in this case, the BMS is not connected to the MPPT remote terminal, this is because if charging needs to stop, the BMS tells the Cerbo to stop charging and the Cerbo tells the MPPT and the inverter to stop charging via DVCC by setting the charge current to zero Amps. When charging, the BMS does not control the chargers, they still follow their own charge settings. DVCC can also transmit the battery or SmartShunt voltage to the MPPT so it can compensate for cable losses, if the battery wants 14.2V and there is 0.2V voltage drop in the cables due to resistance then the MPPT will run up to 14.4V at its terminals. Without this, the MPPT would be at 14.2V and the battery at 14.0V. This can not take place for the older Orions but the newer Orion XS has this feature. The Cerbo also allows monitoring etc.
To finish off, an example of my system, there are schematics available, I have the Lynx Smart BMS with NG batteries, MPPT, inverter, alternator (with external regulator rather than an Orion but the same applies) and solar charger all connected to the Cerbo as is the BMS. The BMS acts as a master charge controller, it tells the Cerbo what charge voltage it wants and the maximum allowable charge current. The chargers are all under direct control of the BMS / Cerbo, they do not use their own settings, just do what the Cerbo tells them via DVCC. There can be some prioritisation in DVCC control if the allowable charge current is lower than what can be produced. If the BMS needs to stop charging, the charge current is set to zero and the Cerbo shuts down all the chargers, there are no cables to the remote terminals on the chargers, it is all done via comms cables.
Thank you very much for your reply and you have certainly filled in a few gaps in the Victron information I have read to date - much appreciated.
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