[Art]

We all know in a storage application, AGM will self discharge and Lithium will also. None of us use our batteries as stored (unhooked and resting) and we all have many parasitic loads going full time, so float charge is a convenient method to keep batteries full. The newer Magnum inverters go to a full charge state and stop charging until the voltage reaches 12.8 then go back to float charge. Relion publishes float voltage for the Insight line as does Battleborn. Battleborn’s self discharge is 2 – 3% monthly and Relion up to 3%.

[Dorel]

Our bus lives 50′ from my Lazyboy. It gets tinkered with almost daily. When not in use, which is most of the time for most motorhomes, Renogy and Relion recommend that their lithium batteries be stored at 30% to 50% state of charge (SOC) to minimize irreversible capacity loss.

Lithium battery self-discharge rate is negligible. When disconnected from parasitic draws, there is no need to float charge them.

When we get home from a trip we “discharge” our three 200ah house lithium batts down to about 13.1v = 40% SOC. Then, we turn the inverters and 12v master off. Now the house batts are disconnected from any and all parasitic draws.

We have never left our bus plugged in to shore power when not in use. If necessary I’ll temporarily hook a small 12v trickle charger up to the lead acid genny and/or chassis batts to keep them healthy.

I take the bus out for a 1 hr cruise monthly. The bus, the batteries, and me love it.

[glen]

If our coach was at a remote location it would definitely be powered down at the end of a trip, but with it 15 paces from the house we keep it powered up 100% of the time except when swapping batteries, something I won’t be doing again. We like the convenience of not only having it powered up so we can go in and out of it anytime to swap out clothes or get something from the fridge or just to monkey with minor repairs or cleaning. A primary reason to keep power to it is because it is a pain going through the steps to put it to sleep or to wake it up.

I cannot speak about other conversions but there is a specific sequence required to power it down and up and there is a risk of damage if it is not followed.

[Jon]

I posted this video primary for folks that are afraid of using their current invert/charger for lithium batteries. You comment do bring up a big difference in our batteries than the guy in the video. Our batteries general have some type of constant draw.

[Dick]

I cannot relate to other coaches because inverters and how they are set up may be different. My coach has Outback inverters and when power (shore or generator) is applied to them they go into bulk charge mode regardless of the SOC of the Li batteries. Even after a day of driving when the Li batteries have a near full charge this happens.

But as long as power to the inverters remains the inverters go into float and at that point go into “silent” mode. In silent mode they no longer apply float current to the batteries until the batteries drop to around 12.6 or 25.2 depending on if the coach is a 12 or 24 volt coach. Once the batteries reach that voltage level, unlike conventional batteries Li batteries have very little SOC left, but that is OK. They are going to get a float charge when reaching that point and when they reach that level again the inverters go back to silent mode.

My coach has a lot of phantom loads and the cycling in and out of silent mode is normal and OK. But I learned even with an uninterrupted power supply to the inverters I have to realize, unlike AGM batteries they may not be fully charged depending on their voltage when power to the inverters is removed. The Li batteries however get more fully charged when the bus is started, which is OK, but if we have a power outage I have to be prepared to get the generator running to fully charge them again if power goes off when their voltage is down to 12.6 or 25.2 because at that point they are close to when their power drops off fast and they can go into shut down.

The bottom line is Li batteries are great, but depending upon various conditions like an inverter in silent mode or cold temperatures to name two they are going to be different from what we were used to.