Lithium Batteries

[msmith1199]

Just downsized from a Class A DP to a Class B+. I got the residential fridge in the new motorhome so power when off the grid is going to be more of an issue that it was before. I’ve been looking at Lithium batteries and they look like a good solution for me. Only problem I see is physical size. The two current batteries I have are 11.5 inches long and they are a tight fit in the battery compartment. All the lithium batteries I’ve seen are at least 12.5” or longer. So they won’t fit in the existing battery compartment without modifications. But those are all 100AH batteries. I see they also have 200AH lithium batteries. They are a lot longer, over 20 inches, but one of those batteries will fit in the compartment versus two 200AH batteries. So not only does the 200AH battery have a smaller footprint than two 100AH batteries, they are also quite a bit cheaper than buying two 100Ah batteries.

Anybody see any issues in going with one 200ah battery versus two 100ah batteries?

[BFL13]

She wants to keep the charging to 50 amps each so 100a for the two. Meanwhile there have been posts that the alternator will fry from trying to charge the thirsty Li house batts.

Sounds like the way to go is disconnect/disable alternator charging and just leave in the Aux start from the house feature if ever needed.

[msmith1199]

01tundra wrote:

Bert the Welder wrote:
And just for the sake of wondering.... for temps that cold, could some sort of heat pad, blanket or bag not be used to keep the lith's warm enough to function properly? (I'm picturing a Domino's pizza delivery electric warmer bag) Or, perhaps, would moving your batt's inside your camper living space. Obviously if you go with the SiO2, your good to go. But for those with Lith's already, are there options if they are occasionally stuck in temps that cold?

Or mount them inside the trailer instead of outside, which eliminates the low temp operation issue and increases security. Or buy one of the brands that has internal heaters or use the heating pads offered if you'd prefer to keep them outside. The entire temperature argument is a non-issue in my opinion.

It’s not relevant to my original question as if it’s 40 below outside, you won’t see me there! I do live in Nevada but the lowest temp I’ve even seen here is about 12 to 15 and when it’s that cold the motorhome is comfortably stored away in its indoor storage.

[msmith1199]

Ok, well this subject took off since I started it. Hadn’t been back in a while so I read some of the newer replies but not all. So I’ll get on to my next question. I went ahead and bought two Battle Born 100AH lithium batteries. $2100 for both if anybody cares. There were some cheaper alternatives out there, but the Battle Born factory and factory sales center is a few miles down the road so I opted to pay a couple of extra bucks to have them close by. And they had some mock up batteries at the office so I was able to go down there and use their mock ups to make sure they would fit in my battery compartment. They fit.

So I found out my converter actually supports Lithium batteries with just the flip of a switch. So once I install the batteries just flip the switch and we’re good. But, the lady who I bought them from, said that since my RV has a 230 amp alternator and that need to install a DC to DC charger to bring it it down to 100 amps for charging the battery. She seemed to know what she was talking about but I don’t know her background so I thought I’d ask here. Anybody else that switched to lithium install the DC to DC charger? I know the motorhome is already set up to charge the house batteries from the alternator but I’m assuming the lead acid batteries don’t need this DC to DC charger and can take all the power from the alternator? I’m not an electrician so I’m not sure how this stuff all works.

[nightshift]

Or you could just do this.

[pianotuna]

msmith1199 wrote:


Anybody see any issues in going with one 200ah battery versus two 100ah batteries?

It is preferable to have one 200 amp-hour vs two 100 amp-hour jars. It might cost more to do so.

[pianotuna]

Joins 3 tons in my Mylar suit, complete with a chain to drag on the ground a la Marley's Ghost.

[Stanfordstander]

msmith1199 wrote:
Just downsized from a Class A DP to a Class B+. I got the residential fridge in the new motorhome so power when off the grid is going to be more of an issue that it was before. I’ve been looking at Lithium batteries and they look like a good solution for me. Only problem I see is physical size. The two current batteries I have are 11.5 inches long and they are a tight fit in the battery compartment. All the lithium batteries I’ve seen are at least 12.5” or longer. So they won’t fit in the existing battery compartment without modifications. But those are all 100AH batteries. I see they also have 200AH lithium batteries. They are a lot longer, over 20 inches, but one of those batteries will fit in the compartment versus two 200AH batteries. So not only does the 200AH battery have a smaller footprint than two 100AH batteries, they are also quite a bit cheaper than buying two 100Ah batteries.

Anybody see any issues in going with one 200ah battery versus two 100ah batteries?

My batteries once melted a hole in my pants pocket

[3_tons]

Now entering the FDZ (fascinating discourse zone), I’ve just donned my tin-foil hat - lol

3 tons

[pianotuna]

Bert the Welder,

Potting would not work well as the cells need to be cooled.

[MrWizard]

The cheapie Chinese drop ins
Pot the inside perhaps to keep the smaller cells they use from rattling around

Will Prowse on YouTube has opened several different drop in 12v LiFePo batteries to show the quality or lack of quality
One had been filled with glue after assembly

He also did capacity tests on each one
And he has an interview with Battle Born

AFAIK The good quality ones are not potted

[Bert_the_Welder]

With regards to vibrations, etc. effecting the connections of all those smaller batt's making up the larger box in that rendering in the posted link (which was neat to see. Thanks) I wonder if missing from the rendering is any type of potting? Yes, filling the box full of epoxy would nix any type of servicing. But one still wonders.
Or one of you smart fella's may already know the answer to this....

[MrWizard]

This is a perfect example of large cells
(4) 100 ampHr 3.2v cells make (1) 100 amp HR battery

(5) batteries in parallel make a 500 amp HR battery

Just like stringing (5) 6 cell 12v batteries in parallel

The difference, everything is in one Box/Container
The connections are all inside box,
With lead acid cell connections are in the box and battery to battery is outside cabling

Some of these arguments are nitpicking , trying to turn mole Hills into mountains

[Itinerant1]

pnichols wrote:

Itinerant1 wrote:

pnichols wrote:

FWC wrote:

pnichols wrote:

Well ... reading this clip below from the Azimuth Solar Products Si02 webpage
https://azimuthsolarproducts.com/product/12v-108ah-ultra-long-life-battery/ under the "Additional Information" tab:

---------------------------------------------------------------------------------------------
Battery Type
SiO2 Composite Electrolyte Battery

Nominal Capacity (25°C/77°F)
108 Ah (1296 Wh) @ 20 Hour

Nominal Voltage
12V

Max Charge Current
27A

Max Charge Voltage
14.7V

Internal Resistance (25°C/77°F)
=< 6 m?

Max Discharge Current (25°C/77°F)
800A(5S)

Depth of Discharge
100% DOD

Operational Temperature
-40?C to 65?C (-40?F to 149?F)

Self Discharge
< 1.6% per Month

Life Cycle
3400 Cycles at 40% DOD; 1500 Cycles at 80% DOD; 620 Cycles at 100%
DOD

Dimensions
17.2 x 33 x 22 cm (6.77 x 13 x 8.66")

Weight
31.5 kg (69.4 lbs)

Manufacturer
Soneil International Ltd.

Warranty
2 Years Workmanship
---------------------------------------------------------------------------------------------

It sure looks to me like their SiO2 batteries function in a far, far superior way as compared to good old regular lead acid (liquid or AGM) batteries. Crystals are not the same as liquid or liquid absorbed into mats.

Note that the SiO2 batteries can even be discharged to "zero" about 620 times - which I would never think of doing even once, with any battery in my RV - no matter what the chemistry. (Excluding a capacitor battery of course!)

BTW, that maximum charge current of 27A is perfect for us folks with only 130 alternators when underway, and for us drycamping RV folks with only stock converters and very small portable generators.

The spec actually says discharged to 100% DOD (ie pull the full rated capacity out of the battery), not to zero (volts). As I pointed out this claim is not really substantially different from what deep cycle flooded battery manufacturers claim (see the graph I posted earlier with ~500 cycles to 100% DOD). I am not sure I believe either of these claims, just pointing out that the claims are about the same.

Also note that Gell Cells have a sulfuric acid electrolyte solidified with SiO2 (silica), the difference is that these appear to have more SiO2, but the concept is the same.

What spec do you think is far, far better?

Note that I did not say zero with the word "volts" after it. I of course meant zero state of charge.

SiO2 cycle life - as seen in the SOC graphs for it - sure seems quite superior to that of my current high-end deep cycle AGM batteries. Combined with SiO2 cold weather performance and their price - I'm wondering why continue with AGM when mine wear out, or mess with lithiums and their price for only part-time camping use.
That sums it up pretty well, as a part time camper the dropin lfp cost doesn't offset the benefits for your needs.

BTW, regarding drop-in size RV lithium batteries, take a look inside them to see all the inter-connections inside that gotta stay solid and corrosion-free year of year and vibration after vibration. The number of connections decreases reliability in any piece of electrical equipment or circuit. When are drop-in size lithium RV batteries going to have only three or six large cells?

Most dropins are sealed batteries and you have to go out of your way to open one up which probably void any warranty it had.

Connection, corrosion and vibrations could be a consideration but I think that's stretching it to worry about or why stop there, vehicles and rvs with electronic and computer components are in the same conditions and even more exposed.

Nominal voltage of the cells are 3.2v which is why they are built 4 series combination for 12.8v nominal, 3 or 6 cells doesn't work out so well for voltage.

Here's how at least one model of 100AH vehicle drop-in LiFePo4 lithium battery is constructed:
https://www.lithiumion-batteries.com/uploads/files/15019/12V%20100AH%20Internal%20Design%20PDF.pdf

That sure looks like a lot of "little batteries" hooked up together with a lot of inter-connections that may/can eventually fail. I don't know if Battle Born LiFePo4 lithium batteries are also built of a bunch of small cells - but I bet they are. We're not talking about printed circuit board or integrated solid state electronics here - but a bunch of physical cylinders that have to be kept in place with secure connections between them year after year. Plus how many of those little individual lithium cells have to fail before the entire battery can no longer function properly?

Four (4) larger 3.2V 100AH LiFePo4 cells in series would make a 12.8V 100AH LiFePo4 battery ... with a lot less inter-connections - very similar in construction and fully charged voltage to good old vibration proof AGM batteries.

However, I'm betting that the technology of LiFePo4 battery cells is such that a large pancake type design - like the plates in lead acid based batteries - is difficult or impossible or unsafe to produce for use in a commercial drop-in vehicle sized lithium based battery. Hence drop-in LiFePo4 vehicle batteries must be made up of a bunch of "kludged together" small cells.

So how many failures of said battery design have there been? Or is this one of those debates where you throw enough **** against a wall something is bound to stick?

I don't know my 4s5p setup is pretty easy and straightforward even with all that scary electronics on them.



I wouldn't even call that pdf image you posted a "kludged together" but like 3tons said I'm not looking for the boogie man.

[3_tons]

pnichols wrote:

3 tons wrote:
“ That sums it up pretty well, as a part time camper the dropin lfp cost doesn't offset the benefits for your needs.”

If one’s looking for a Boogieman, they’ll tend to find one behind every tree...

3 tons

Well ... there's a whole area of engineering that addresses reliability of complex systems ... and what makes up a "complex system" is a whole lot of separate components that all have to function or the whole system fails. 😉

You might be pointing to say the evolutionary path of the transistor, lap-top computer, or fly by wire commercial airliner, all ‘solid examples’ of how engineering meets these not so insurmountable challenges...I suspect that at this juncture LiFePo4 failure analysis has become a rather mature subject matter as indicated by Lithium batteries aboard Boeing’s own aircraft...JMO

3 tons

[pnichols]

3 tons wrote:
“ That sums it up pretty well, as a part time camper the dropin lfp cost doesn't offset the benefits for your needs.”

If one’s looking for a Boogieman, they’ll tend to find one behind every tree...

3 tons

Well ... there's a whole area of engineering that addresses reliability of complex systems ... and what makes up a "complex system" is a whole lot of separate components that all have to function or the whole system fails. 😉