I have recently upgraded my house bank to LiFePO4 from AGM. I was using an ACR to keep the start bank charged from the house bank. This is apparently not the best idea with mixed chemistry, so I’ve installed an OrionXS to charge the start AGM bank from the LiFePO4 house bank. All charging sources (2 x alternators and 2 x MultiPlus 3000) charge the house bank.
The ACR I used is a Blue Sea 7620 that has manual capability. ie it could work as an automatic ACR, it could be turned off to never permit the battery banks to be connected, plus - and this is the big advantage - it can be “turned on” which connects the banks in parallel, like in an emergency situation if the start bank is dead and you need to start the engines. I want to keep this configuration, understanding that the paralleling can only be very brief, and so on and so on.
Here is the question: with the OrionXS doing its thing, if I hit this parallel switch, I would be effectively shorting the input to the output of the Orion. Is this verboten? Or would it be allowable (even though maybe not really desirable) for the short time this would occur?
Edit to add: it would also be valuable, like it already was when installing the lithium bank, to provide power to the house from the start if the lithiums died or shut down.
Thx….Randy
Hi Randy. I can’t answer your question but I can give you some food for thought.
My set up also has an emergency start facility achieved via a solenoid that parallels the start and house batteries and I too have an Orion XS that charges the house battery from the start battery which of course gets it’s charge from the alternator.
Your question made me query my own setup. As I originally had it configured, the Orion XS was only ever charging when the engine is running, thus why would I need to use the emergency start facility if the engine is running? Thus not an issue.
However I have recently added a second solar array and MPPT to charge the start battery and any surplus then goes to the house battery thus I could potentially need the emergency start facility whilst the Orion is working from a charge provided by the MPPT.
Following your question, If I ever need to use the emergency start facility I will first go into Victron Connect or Remote Console and disable the Orion before I flick the emergency start switch which energises the selonoid
If you wanted to make a proper job of it, you could use a spare NC contact of the emergency start switch to control the remote control on / off switch for the Orion.
Use the Remote ON-OFF terminals to turn the Orion XS OFF when the parallel relay is energized. See Figure 3.9 in the 50A manual for the different schemes.
Starter batteries that are kept on float charge very rarely go flat, or go faulty. On our yacht (11 years, 57000 miles) I had a 24V house bank and kept the engine and radio batteries on a 13.4V float charge. No problems ever with the starter battery, engine usually started in <3s.
Re the chemistry: 12V lead acid range from 10.8 - 14.4V, but should never be discharged below 12v (no load voltage). Lithiums (LiFePO4) can operate from 11.2 to 14.4, so there is no real issue in direct parallel - on charge - for the 2 batteries as long as the alternator voltage does not exceed 14.4V. At 24v & 48v the voltages are sufficiently different that this cannot be done safely. However, one should be cautious about trying to start an engine from a lithium battery - you need to make sure that the battery can handle the peak current - which can hit up to1000A (depending on engine size) for a few seconds.
Thx @CharlieJ, that sounds like it might be just the ticket. I’ll look more closely at that remote on/off capability to confirm if I can set it up so,that the Orion is on all the time, and turned off when the ACR parallel is energized.
Thx for the reply @MikeD. I do understand all that, and for all the reliability of the start bank I wouldn’t be going out to add the paralleling capability. But it is already there and functioning so I’d like to keep it in place if possible.
And it’s not the voltage range I’m concerned about, it’s that when the banks are paralleled by using the ACR switch, the Orion is effectively being shorted out from input to output. I don’t know if this is not allowable, but I can imagine it might not be. Remote controlling the Orion as discussed above sounds like an elegant way to avoid the whole issue.