lithium batteries

[timlsalem]

I have something eating at me and can't find an answer anywhere. I have a 30A breaker between the panels + and the charge controller so I can disconnect the panels when I'm in travel day mode. and just use my DC to DC charger. I am set up right now at my homebase, in Arizona, and am using the sun to keep the batteries charged up instead of being plugged in to 30A shore power. What I'm wondering about is, should I be letting the batteries discharge at all or just keep doing what I am doing. They remain fully charged during the day but at night they do discharge a little bit but always recharge to full during the day hours. What do you say? Am I harming them by doing this or will they be alright? Thanks in advance for any information on this you can provide me with.
Tim

[TucsonJim]

If your batteries are lithium iron phosphate (LiFePO4), They will be just fine with small cycles. In fact, most of them are rated for about 3,000 full cycles. They will last even longer with small discharge cycles.

Jim

[BobinICT]

When home our rig is on shore power but the converter remains off. (Mainly for AC and fridge when we turn it on a couple of weeks before leaving) The 12 volt system always runs on the LiFePO4 with the 600 watts on top doing what it is designed to do. I very seldom turn on the converter and it's mainly used as a backup charger when needed which is not very often. Also, I pulled the breaker supplying charge to the trailer when we are driving. I, do, not, want to end up replacing an alternator.

[howson]

I have something eating at me and can't find an answer anywhere. I have a 30A breaker between the panels + and the charge controller so I can disconnect the panels when I'm in travel day mode. and just use my DC to DC charger. I am set up right now at my homebase, in Arizona, and am using the sun to keep the batteries charged up instead of being plugged in to 30A shore power. What I'm wondering about is, should I be letting the batteries discharge at all or just keep doing what I am doing. They remain fully charged during the day but at night they do discharge a little bit but always recharge to full during the day hours. What do you say? Am I harming them by doing this or will they be alright? Thanks in advance for any information on this you can provide me with.
Tim

Tim,
I agree with TucsonJim. Even if that small discharge/charge is considered a "cycle" by the (presumably) LifePO4 battery, 3,000 cycles (at one per day) means the batteries are good for more than 8 years. I believe it was acoleman43 that wrote in another post something to the effect, "there's a lot more to worry about in our RV's than how long the LifePO4 battery will last--just use them and enjoy your RV".

Howard

[timlsalem]

( [/QUOTE] Also, I pulled the breaker supplying charge to the trailer when we are driving. I, do, not, want to end up replacing an alternator.) I installed a Renogy 20A dc to dc charger on the trailer with 2.0 gauge wire running to a 20A fuse in the engine compartment and that connects to a battery shut off so I can disconnect it from power, just for that purpose. Thank you for the response. Very appreciated. I was about to dig up my paperwork on my batteries, which would have taken a long time I have no idea where I stuffed them, so I could contact the dealer and ask them. Tim

[timlsalem]

If your batteries are lithium iron phosphate (LiFePO4), They will be just fine with small cycles. In fact, most of them are rated for about 3,000 full cycles. They will last even longer with small discharge cycles.

Jim

Yes, they are two 100aH LiFePO4.

[TucsonJim]

Even if that small discharge/charge is considered a "cycle"

Howard

howson - I've discussed this with Battle Born Batteries technical staff when they attended the Las Vegas rally in 2019. They consider a "cycle" a full charge and full discharge. A 50% discharge and recharge would be the equivalent of 1/2 of a cycle. The way they explained it, their batteries would supply 3,000 full cycles, or nearly 6,000 1/2 cycles.

I'm not sure if all LiFePO4 manufacturers have the same position.

Here's the cycle information from Battle Born's FAQ page:
"A cycle is the process of fully charging and discharging a battery. Our LiFePO4 batteries can be discharged nearly 100% for thousands of cycles without shortening their lifespan."

Jim

[colan]

Agree with the other posts, don’t worry about the small daily discharges.

Question:

What is the reason for disconnecting the solar panels when traveling? I leave ours on with the refrigerator set to run on electric. Arrive at the destination with fully charged batteries assuming I don’t drive to well after dark.

can disconnect the panels when I'm in travel day mode. and just use my DC to DC charger.
Tim

[acoleman43]

I have something eating at me and can't find an answer anywhere. I have a 30A breaker between the panels + and the charge controller so I can disconnect the panels when I'm in travel day mode. and just use my DC to DC charger. I am set up right now at my homebase, in Arizona, and am using the sun to keep the batteries charged up instead of being plugged in to 30A shore power. What I'm wondering about is, should I be letting the batteries discharge at all or just keep doing what I am doing. They remain fully charged during the day but at night they do discharge a little bit but always recharge to full during the day hours. What do you say? Am I harming them by doing this or will they be alright? Thanks in advance for any information on this you can provide me with.
Tim

Yes, you are probably shortening the lifespan of your batteries. However, that lifespan will probably far exceed the life of your trailer ownership. If you do have the trailer 10 year or 15 years down the road, just get new batteries. By then there will be better technology and you will want to replace them anyway

Even at 3000 cycles, that is 20X more than a lead acid battery. I say use the batteries in a way that is convenient to you and don't sweat it.

[timlsalem]

Agree with the other posts, don’t worry about the small daily discharges.

Question:

What is the reason for disconnecting the solar panels when traveling? I leave ours on with the refrigerator set to run on electric. Arrive at the destination with fully charged batteries assuming I don’t drive to well after dark.

It's just something I do. With the DC to DC charger I don't need the panels to keep the batteries charged or to run anything AC inside the trailer while driving.

[howson]

It's just something I do. With the DC to DC charger I don't need the panels to keep the batteries charged or to run anything AC inside the trailer while driving.

You can safely use the solar and DC-DC charger simultaneously--won't hurt a thing as they work together without any issues. I do this all the time. Very similar to having solar and the RV's converter working together. No problems at all.

Just an FYI. What you're doing isn't "wrong".

Howard