Expedition Vehicle selection thoughts?

[pnichols]

A few other random thoughts.

There are advantages to forward control - higher % of "useful" length.
Having owned both, there are disadvantages to slide-in and drop-in compared with built-directly-onto-the chassis. The advantages of built directly include significantly lower weight, lower CofG (water etc is below the chassis instead of above) and better storage and access to that storage.

I use AGMs. They can be configured to do everything that a Lithium can do. They are all "just batteries".
AGMs are very much cheaper. They can easily be built up in parallel. A dud cell can simply be removed.
Lithiums are significantly lighter. That may or may not be of value.
I charge the AGMs from solar and/or direct from the alternator. I also use an AGM crank bettery, so all batteries are compatible.
Cheers,
Peter
OKA196 motorhome

One of the Lithium battery advantages claimed by many is their fast charging capability. That's probably due to their low internal resistance.

Well, AGM batteries also have low internal resistance and hence can be charged much faster than liquid acid batteries. One of the top AGM battery lines in the world is Lifeline AGM batteries. They claim that some of their larger AGM batteries can accept up to 100 amps when charging. I believe this charging rate is right up there with claimed Lithium battery charge acceptance rates.

 

[gregmchugh]

One of the Lithium battery advantages claimed by many is their fast charging capability. That's probably due to their low internal resistance.

Well, AGM batteries also have low internal resistance and hence can be charged much faster than liquid acid batteries. One of the top AGM battery lines in the world is Lifeline AGM batteries. They claim that some of their larger AGM batteries can accept up to 100 amps when charging. I believe this charging rate is right up there with claimed Lithium battery charge acceptance rates.

AGM charging is a 3 phase process...

Bulk charging at high charge rate to 80-90% state of charge.

Absorption charging at a slower rate for the last 10-20% to 100% state of charge which takes 1-2 hours.

Float charge to remain at 100% state of charge.

Solar works well for topping off the batteries during absorption phase. AGM batteries must be brought to full charge regularly in order to have a long life.

Lithium’s have no Absorption phase and can be charged at a high rate until full. Lithium’s also do not need to be brought to full charge. From a charging point of view those are two advantages to lithium. Lithium’a should not be charged when the cell temperatures are below freezing, one disadvantage of lithium charging.

 

[DiploStrat]

... I believe this charging rate is right up there with claimed Lithium battery charge acceptance rates.

Owning Lifeline AGMs and having tested lithium iron batteries, I would disagree with this, strongly.

Lifelines may charge faster than flooded lead acid, but they are very slow compared to lithium.

YMMV. (But, as noted, I doubt it. )

 

[pnichols]

As gregmchugh's post above implies, good AGM batteries can be brought up to 80% - 90% state of charge during a (14.xx volt) bulk charging phase.

From what I have read, this bulk phase for AGM batteries can complete in a pretty short time if one has a charger that can deliver high currents during bulk phase. I'll bet that this 80% - 90% level is reached for AGM batteries in about the same length of time as 100% full charge is achieved for lithium batteries using a high current charger holding at 14.xx volts.

So ... the faster charging advantage of lithium batteries over good quality AGM batteries (with any given high current capable charger) only applies for the final 20% - 10% of charging between the two battery types.

It appears that what it boils down to is -> does one want to spend the big bucks for lithium batteries over good AGM batteries to get:
1. Faster charging over AGM during only a small portion of any given total capacity,
2. a lower level SOC draw-down point over AGM so charging can be less often,
3. lighter weight over AGM for any given battery bank capacity, and
4. the disadvantage of not being able to use lithium batteries mounted in an unheated RV compartment during below freezing weather.

Not considered by most are these disadvantages of current lithium batteries as used in the standard drop-in sizes for RV power:
1. Their internal cell structures could be, over time, prone to failure because they employ a bunch of small cells wired together with a lot of interconnections required.
2. Their internal BM systems require circuitry requiring PC boads with traces, solder joints, and integrated circuits, all of which can and do fail.

 

[gregmchugh]

As gregmchugh's post above implies, good AGM batteries can be brought up to 80% - 90% state of charge during a (14.xx volt) bulk charging phase.

From what I have read, this bulk phase for AGM batteries can complete in a pretty short time if one has a charger that can deliver high currents during bulk phase. I'll bet that this 80% - 90% level is reached for AGM batteries in about the same length of time as 100% full charge is achieved for lithium batteries using a high current charger holding at 14.xx volts.

So ... the faster charging advantage of lithium batteries over good quality AGM batteries (with any given high current capable charger) only applies for the final 20% - 10% of charging between the two battery types.

It appears that what it boils down to is -> does one want to spend the big bucks for lithium batteries over good AGM batteries to get:
1. Faster charging over AGM during only a small portion of any given total capacity,
2. a lower level SOC draw-down point over AGM so charging can be less often,
3. lighter weight over AGM for any given battery bank capacity, and
4. the disadvantage of not being able to use lithium batteries mounted in an unheated RV compartment during below freezing weather.

Not considered by most are these disadvantages of current lithium batteries as used in the standard drop-in sizes for RV power:
1. Their internal cell structures could be, over time, prone to failure because they employ a bunch of small cells wired together with a lot of interconnections required.
2. Their internal BM systems require circuitry requiring PC boads with traces, solder joints, and integrated circuits, all of which can and do fail.

There is still the issue that AGM batteries will not last if they are not brought to full charge regularly which is not needed for lithium.

I am also suspect of the some of the drop in Lithium batteries in terms of their reliability and ruggedness and quality of the BMS. The marine batteries from Mastervolt, Victron, and Lithionics seem to have a proven record of reliability and ruggedness and effective Battery Management Systems but you do pay extra for this...