Lithium Iron Phosphate Batteries

[GenXair]

Has anyone switched out their stock batteries to Lithium Iron's?
I want to know if they live up to their power & life claims and if it helped reduce hitch weight.

Thanks

[ghaynes755]

There are multiple posts from BAB and SWITZ on their installs. Growing number of folks doing lithiums. I'm getting my solar install this weekend and went with lithiums. 400ah is 110#.

[switz]

In May of 2014, we replaced the two factory lead acid batteries with four Lifeline 6ct 6Vdc 300 amp hour GSM batteries (configured to be 12Vdc and 600 amp hour capacity) weighing 93 pounds each for a total of 372 pounds in a custom 140+ pound stainless enclosure on the the front of the Classic 31' trailer. We also installed the eight 100 watt solar panels at that time. Actual tongue weight was 1375 pounds camping ready.

Two weeks ago those four batteries and enclosure were removed and replaced with a single lithium iron phosphate battery with the same 12Vdc 600 amp hour capacity that weighed 168 pounds and was mounted inside under the front sofa. We reduced tongue weight over 300 pounds.

The Lifeline batteries could provide up to 50% of their rated power while the lithium iron phosphate can provide between 80 and 90% of their power capacity.

Both the TriStar MPPT 60 solar charge controller and the Magnum MS-2812 converter were reprogramed to the details necessary for the new battery which charges to 14.3 Vdc

Paying close attention to the correct power usage and management will enable the battery to last much longer than lead acid and now the Lifelines. These are still new technology and real world longevity has yet to play out.

[Photobum]

How much did the new battery cost and what are the dimensions????

[ckottum]

Great technology, especially for us Airstreamers with loaded hitch weights well beyond the 10-12% needed for safe towing. And the wish for a little more battery power at times.

The major or perhaps only issue to some is price of these batteries and equipment to charge them. Although I'm wondering if that is truly significant for those who keep and use their Airstream for 10 years or more.

Another, less costly way to improve battery performance while reducing hitch weight is getting larger AGM batteries and locating them nearer the center or back of the Airstream.

cheryl

[ghaynes755]

You can see prices and dimensions at one of the two primary folks that have experience in the RV market. Welcome to AM Solar_Your RV Solar Specialists since 1987 and www.elitepowersolutions.com. Ball park is about $800 per 100ah when you include the cost of the BMS (Battery Monitoring System) that is essential to success, life and not killing the batteries. This is different than the charger/inverter and solar controller. Lithiums have need their own BMS.

[switz]

Check this link to better visualize how the battery size can be manipulated:

AM Solar, Inc.:

Referring to the AM Solar battery we have installed, there were four 3.2Vdc subsets. When wired in series, we have 12Vdc nominally.

Each subset had six identical 100 amp hour cells at 7 pounds each wired in parallel. So each subset weighed 42 pounds and had 600 amp hour capacity. The entire assembly weighed nominally 168 pounds. AM Solar uses solid copper flat bar stock about ⅛" thick and over 1" wide to jumper between each cells posts to its neighbor and to jumper between the subsets.

Thus our battery is rated 12Vdc and 600 amp hours of capacity.

The physical size can vary depending how one positions the four subsets. Ours was configured to have a roughly 11.25" x 29 1/16" foot print. We needed about 10" of height to clear the terminals and battery management chips.

I would expect that by next year, the cost of these cells will have decreased significantly. Probably not as much as ball point pens did going originally from nearly $100 down to the BiC for $0.29 today.

The individual 3.2Vdc 100 amp hour cells can be transported via some public carriers. They balk at bundles of the 3.2Vdc cells strapped together, let alone a complete battery strapped together.

Thus I drove from Phoenix to Eugene Oregon to pick up the battery and take it with me to Phoenix and then onwards to A&P Vintage Trailer Works in Paradise, Texas where all the conversion work has been done on our Classic.

[lewster]

Here's a shot of a 400 amp/hour lithium pack going in a new Bunkhouse 30. The available space is directly over the axles. We (AM Solar) arrange individual 3.2 VDC/100 amp-hour cells into banded packs of varying amp/hour capacities. All terminals on each pack are paralleled to form a single (in this example) 3.2 VDC pack rated at 400 amp/hours.

Each pack is then connected in series to form one, large 12.8 VDC battery. There are electronic cell balancers required (one for each 3.2VDC/400 AH pack) and AM Solar's proprietary Battery Monitor System, which prevents ruining the battery from excessive over or under charge situations.

Lithiums DO require very specific charge voltages that are not the familiar 3-stage charging. The charging systems MUST be upgraded (in this case, a Magnum MSH3012M hybrid inverter/charger and 540 watt solar array with Blue Sky 40 amp solar charge controller) to properly charge these lithiums. Another benefit is their extremely rapid acceptance of charging voltage at very high amperages. This translates into very fast re-charging, sometimes in as little as 30 minutes!!!

This installation will effectively reduce the tongue weight on this 30 by approx. 140 lbs. (the weigh of the 2 Interstate group 24 batteries on the tongue and removal of the WFCO inverter.

They are gaining in popularity, as I have 5 lithium installations scheduled for inclusion in the larger solar charging systems I am installing in the next 5 weeks, along with 5 more for folks who already had their solar/inverter systems installed by me in FL this past Winter/Spring and are headed to Hood River to complete their systems.

Pricey....YES! 15 year battery live............YEP! No maintenance ever.....OH YAH!!!!! Weight reductions.........you bet!!! 80% depth of discharge with no capacity loss, battery damage or decrease in usable battery life.........for sure!!! This means that you get 80 usable amp/hours from each 100 amp/hours of battery capacity with no effect on overall battery health. They also do not exhibit voltage sag, which is present in every lead acid battery. This is the decrease in battery voltage output as you use them. Lithiums have a continual consistent voltage output and as such (for you techies out there) Peukert's theorem does NOT APPLY to these batteries.

Price it out over their anticipated life span and they come out less than AGM lead acid based systems and leave liquid cells in the dust. As volume increases pricing should moderate, but at the moment, these are flying out the door!

We have been discussing the larger size lithiums, but what about smaller ones? Here is an example: the stock Interstate group 24 batteries weigh around 50 lbs each and have a usable capacity of 80 amp/hours at 50% depth of discharge. You can achieve that same capacity of 80 amp/hours with a single 100 amp/hour lithium pack at 80% depth of discharge weighing just 28 lbs!

[AWCHIEF]

Price wise still way out of my reach. If someone wants to write me a check I would not turn it down.

[dznf0g]

Appreciate it Lew...I am definitely one who will await "price moderation". Keep us informed.

[ckottum]

We'll need a lower price as well, but look forward to this technology. We have learned to "get by" traveling with our factory solar and leave the generator at home. Much prefer it, these batteries and a little more solar will surely improve our travel experience.

cheryl

[gecko]

Our current hitch weight on International 28' with four Lifeline AGM's (440 amps--220 usable) mounted forward is 1260. We anticipate a significant weight reduction. As far as cost is concerned, we considered relocating the AGM's to the rear (front of bed), but the cost to relocate everything from current forward location was quite expensive, and figured into the relatively simple swap out of the new lithiums for the AGM's. Lew Farber will be doing the work next month.

[KJRitchie]

How much capacity could you stuff in the A frame battery box?

For 25fb queens with the Parallax style converter box in the bed frame do you just pull out the lower guts and retain the AC and DC fuses? Install the litium charger inside the bed near the old converter?

When connected to the tow vehicle what happens with the charge line? Is it run to the new charger so it can continue charging the batteries?

Kelvin

[lewster]

This is where it gets a bit 'sticky' you can't place the lithiums in an outside environment due to their electronic cell balances. They don't out gas, as this is not endemic to the lithium technology.

I always disable the TV's charge line when placing Lifelines in my installations, per direction from Lifeline as the constant alternator output will overcharge AGMs

Same goes for lithiums. They charge so quickly and have such great charge retention and draw capacity that it's unlikely that any charging from the TV is necessary.

Solar is the icing on the cake!!!


Lew Farber
RVIA/RVDA Nationally Certified Master Tech
Master Tech Energy Systems, Inc.
AM Solar Certified Installation Center
Lifeline Batteries**Magnum Inverters
541-490-6357

[KJRitchie]

I have a 200w portable solar panel system. I guess I'd have to ditch the built in controller and connect the panels to cabling connected to a lithium friendly controller.

So for a 25fb queen you install a lithium pack under the queen bed and the A frame battery compartment becomes storage.
Kelvin

[field & stream]

Anyone know the answer to this question: When not in use, and not being charged, how do lithium batteries hold their charge vs. AGM vs. lead acid?

[open01]

Just getting back to Airstream Life after several years of working too hard. Now putting 1972 31 Sovereign back to road readiness. I have had a single PV panel on the roof for over 10 years, still working. Just upgraded to 31 size AGM battery but found it too heavy for battery box- relocated it to space just behind the curb side axel where it sits on the outrigger- takes up some space in that storage compartment, but allows me to use the original battery compartment for other things. Also, several years ago I mounted a 3.5KVA Generac generator in the frame under the sofa. Runs on propane, upgraded to 40# aluminum cylinders. So, not as high tech as a roof full of PVs or bay full of Lithium batteries, but seems practical for a much more reasonable cost. Still great to hear about the next gen stuff though.

[lewster]

Originally Posted by field & stream

Anyone know the answer to this question: When not in use, and not being charged, how do lithium batteries hold their charge vs. AGM vs. lead acid?

I have had Lifelines retain charge when totally isolated for over 6 months. With Lithiums in the same situation: at least a year and probably longer due to their negligible internal resistance and self discharge rate.


Lew Farber
RVIA/RVDA Nationally Certified Master Tech
Master Tech Energy Systems, Inc.
AM Solar Certified Installation Center
Lifeline Batteries**Magnum Inverters
541-490-6357

[field & stream]

Lew -- thanks for the answer to my question. Looks like next batteries for us will be lithium.

[amaier7771]

"This is where it gets a bit 'sticky' you can't place the lithiums in an outside environment due to their electronic cell balances. "

Lew, why is it that the lithiums cannot be in the outside compartment? I do not understand "electronic cell balances", is that a component?? We have a FC 25FB Twin, so we have a fairly large front center storage compartment right next to the other electrical components, so could the lithiums live in that compartment?

Thanks Lew for your expertise on all of this electrical stuff.