4 x 6V vs. 2 x Lithium

[GoLeafsGo]

Originally Posted by cruzbill

I think you have a pretty good handle on the FLA vs Lithium; mostly comes down to $85 at costco or $1,000 for lithium. I can't wait for lithium prices to come down. Tongue weight, now that's a consideration for sure.

Lots of info on lithium:

https://www.gonewiththewynns.com/sai...hium-batteries

Great link! Thanks.

[Tony Lee]

the lifetime capacity is 10 times longer is true.

So instead of lasting 10 years like my AGMs, and which I have just replaced expecting to get another 10 years good service from, you say I should spend waaaayyy more money and install lithiums that will last me 100 years.

BUT I am 70 years old now!!!

Doh!!!

[GoLeafsGo]

Yes, that's clearly what I'm saying.

[Blackbelle]

Another fact of lithium is they stay at the same rate of discharge as they draw down. Flooded batteries produce less power as they are drawing down. Hence you will notice your lights starting to yellow, and the speed of your fans slowing. I too will be switching to lithium in the next several months. You tube some of the comparison videos, they are pretty telling.

[Blackbelle]

Also they are capable of being fully recharged in several hours compared to flooded batteries that take much longer to fully get to float level.

[Blackbelle]

https://youtu.be/aCT_275ca2g

[Blackbelle]

https://youtu.be/KT9sKfU-sQs

[brulaz]

Originally Posted by twinboat

I think the hold up may be with the charging equipment out there. Lithium batteries charge at a specific voltage and then the charging needs to stop.

The chassis charging system would also need a seperate control to cut of the charging.

A lot of the drop-in LiFeP batteries come with a built in BMS that handles that for you. They'll just stop accepting the the charge when they are full. You do want a charger that gives you the right volts though. Not sure, but a simple V adjustable Power Supply might be all you need.

[twinboat]

Originally Posted by brulaz

A lot of the drop-in LiFeP batteries come with a built in BMS that handles that for you. They'll just stop accepting the the charge when they are full. You do want a charger that gives you the right volts though. Not sure, but a simple V adjustable Power Supply might be all you need.

When the BMS cuts off the charging, I'd have to think it also cuts off the battery output, since it's charging thru the same terminals.

I suppose the house loads can run off the chassis battery but I imagine there could be situations when the isolation relay could cycle open and close, when it sees no voltage from the house battery, causing the BMS cut in and out.

Not sure how that will work out.

[brulaz]

Originally Posted by twinboat

When the BMS cuts off the charging, I'd have to think it also cuts off the battery output, since it's charging thru the same terminals.

I suppose the house loads can run off the chassis battery but I imagine there could be situations when the isolation relay could cycle open and close, when it sees no voltage from the house battery, causing the BMS cut in and out.

Not sure how that will work out.

When any battery is being charged, it is not supplying any current to any loads. The charger is supplying the current to charge the battery as well as to the loads.

I suspect the BMS determines whether amps will go in or go out by comparing battery V versus the "outside" V.

If the "outside" V is higher than the full battery V, then no amps are allowed in and the "outside" V source (solar charger or whatever) supplies the needed amps to the loads.

If the "outside" V drops below that of the full battery V, amps are allowed to flow out, until the battery's allowed minimum V is reached.

Just guessing mind you. I am not an expert.

A fair number of newer battery chargers claim to be able to charge LiFeP batteries. As far as I can tell they are little different from older chargers; they just have a different charge voltage and don't switch to float.

[GoLeafsGo]

All right, back to me

The TT will have a 320W Zamp solar panel system with a Zamp controller from the factory. I purchased a Torklift locking battery box which will be bolted down to the frame for security.

I am considering purchasing 2 x 12V Battle Born LiFePO4 batteries (https://battlebornbatteries.com) and an AIMS 1500 Watt Pure Sine Inverter Charger (http://www.aimscorp.net/1500-Watt-Pu...r-Charger.html).

The TT is a Creekside 21DBS. It will house a family of five on up to month long trips typically split 75% National/State Parks and 25% RV parks. We take a month long trip in July, an 8 day trip at Thanksgiving, and depending on school and other factors, multiple weekend trips sprinkled throughout the year. This being a 4 season type of trailer we might add a Christmas desert trip once in a while. The month long trip usually breaks down to 3 - 6 night stays at several National or State parks, so the batteries get recharged while driving between destinations. I also like to stop for a night at a full hook up place between parks to plug in, recharge, shower fully, do laundry if need be, etc.

We try not to use electronics during our camping trips, but do sometimes throw a movie on for the kids, and charging cell phones, camera batteries, and my laptop are realities. Our previous trailer, a Nash, had a built in propane generator which we would occasionally turn on to use the microwave. The new trailer not having a generator, I would like the battery/inverter system to be powerful enough to run the microwave once in a while.

In 4 years of camping we only turned the A/C on to make sure it was working, so I'm not too concerned about that. I am not convinced I want to tote around a generator, but am willing to do so if necessary.

Am I on the right track?

Any further words of advice are greatly appreciated.

[twinboat]

Originally Posted by brulaz

When any battery is being charged, it is not supplying any current to any loads. The charger is supplying the current to charge the battery as well as to the loads.

I suspect the BMS determines whether amps will go in or go out by comparing battery V versus the "outside" V.

If the "outside" V is higher than the full battery V, then no amps are allowed in and the "outside" V source (solar charger or whatever) supplies the needed amps to the loads.

If the "outside" V drops below that of the full battery V, amps are allowed to flow out, until the battery's allowed minimum V is reached.

Just guessing mind you. I am not an expert.

A fair number of newer battery chargers claim to be able to charge LiFeP batteries. As far as I can tell they are little different from older chargers; they just have a different charge voltage and don't switch to float.

My original statement is about the alternator charging thru the isolation relay, while on the road.

I agree that the battery isn't supplying power when a constant voltage charger is supplying the power, up to its amp output, but automotive alternator varry output by RPM.

As you drop RPMs, there comes a point where it can not support the chassis and house loads. That's when things can get mixed up, since the BMS has the house battery shut down.

[Bugslinger]

GoLeafsGo, let me understand something. You want to minimize your impact on the environment, i.e.. minimize your footprint. Then why did you buy a 27 foot travel trailer???

[Coral]

Originally Posted by twinboat

Both batteries have a 100 amp discharge rate.

Two Battle Born batteries in parallel, equaling 200 AH, will give you a 200 amp discharge rate and handle a 2000 watt inverter.

The 200 AH battery has the same 100 amp draw spec, so it will only handle a 1000 watt inverter.

Just something to consider.

I was actually going with 3 in parallel, my inverter pulls over 200 amps at max load so I need 3