Good Sam Club Open Roads Forum: Are lithium batteries worth the cost?
Open Roads Forum Already a member? Login here.   If not, Register Today!  |  Help

Newest  |  Active  |  Popular  |  RVing FAQ Forum Rules  |  Forum Posting Help and Support  |  Contact  

Search:   Advanced Search

Search only in Truck Campers

Open Roads Forum  >  Truck Campers

 > Are lithium batteries worth the cost?

Reply to Topic  |  Subscribe  |  Print Topic  |  Post New Topic  | 
Page of 8  
Prev  |  Next
FWC

The Wilderness

Senior Member

Joined: 09/12/2020

View Profile



Posted: 04/27/21 08:59am Link  |  Quote  |  Print  |  Notify Moderator

Also to add, Trojan is one of the few battery assemblers to actually provide a real spec sheet for their LiFePO4 batteries:
Trojan Trillium Spec sheet
They spec charging at 0.05C down to -10C, and no limits on discharge down to -20C. As these are warrantied batteries, this is likely conservatively rated.

otrfun

On The Road

Senior Member

Joined: 09/08/2012

View Profile



Good Sam RV Club Member


Posted: 04/27/21 11:45am Link  |  Quote  |  Print  |  Notify Moderator

FWC wrote:

Also to add, Trojan is one of the few battery assemblers to actually provide a real spec sheet for their LiFePO4 batteries:
Trojan Trillium Spec sheet
They spec charging at 0.05C down to -10C, and no limits on discharge down to -20C. As these are warrantied batteries, this is likely conservatively rated.
Yup, the Trojan Trillium spec sheet is very telling. Thanks for the link. They recommend a max. of .13c charge from 0c to 5c. Jumps up to .5c from 5c to 23c. I can see why there's general agreement that <0c should be the cut-off for charging. .05c charge from -10c to 0c is bordering on a trickle charge.

Most folks don't have programmable chargers so they can limit charge current to a specific amount. Based on Trojan's spec sheet I may consider changing the low-temp cut-off for charging our 200ah LifePo4's with our 45a converter a bit higher than its current 0c (32f).

jaycocreek

Idaho

Senior Member

Joined: 12/28/2013

View Profile


Offline
Posted: 04/27/21 12:09pm Link  |  Quote  |  Print  |  Notify Moderator

Nice spec sheet but I don't see anything on internal cell type and how there configured..Battleborn makes a deal about there cylindrical cells and discharging to 0% and stated some other types cannot do that..Just another interesting point other companies don't discuss...

FWC

The Wilderness

Senior Member

Joined: 09/12/2020

View Profile



Posted: 04/27/21 12:15pm Link  |  Quote  |  Print  |  Notify Moderator

I think the actual test data in the paper is probably more telling. There they charge/discharge LiFePO4 cells at 1C, 1000 times at various temperatures. Even after brutal test like this, the battery that was cycled at -5C had only slightly worse degradation than the room temperature batteries. To me that makes it pretty clear that an occasional charge cycle at -5C (or even lower) at a less than 1C rate of charge is not something to be worried about. Cycling at very high temperatures was actually far worse for the battery.

It is up to the user to decide what their requirements are, but for my use I am never going to need 2000+ 100% DOD cycles out of my batteries. In a good year, I am at about 100 nights of use, and most of those are at < 50% DOD, so even if I only get 20% of the rated cycles from my LiFePO4 battery, it will outlast my use. So in my case I don't sweat charging at -10C.

Now if this was an EV where the goal was to have a 200,000 mile lifetime, then the calculus would be different.

I think the most important thing to realize is that there are no black and white rules or limits. You can charge below freezing, you can run down to 0% SOC, you can cycle at high temperatures, it is all a trade off between usability and lifetime.

* This post was edited 04/27/21 12:25pm by FWC *

FWC

The Wilderness

Senior Member

Joined: 09/12/2020

View Profile



Posted: 04/27/21 12:17pm Link  |  Quote  |  Print  |  Notify Moderator

jaycocreek wrote:

Nice spec sheet but I don't see anything on internal cell type and how there configured..Battleborn makes a deal about there cylindrical cells and discharging to 0% and stated some other types cannot do that..Just another interesting point other companies don't discuss...


This is not really important to the end user - just that the battery meets its specifications.

otrfun

On The Road

Senior Member

Joined: 09/08/2012

View Profile



Good Sam RV Club Member


Posted: 04/27/21 04:56pm Link  |  Quote  |  Print  |  Notify Moderator

FWC wrote:

I think the actual test data in the paper is probably more telling. There they charge/discharge LiFePO4 cells at 1C, 1000 times at various temperatures. Even after brutal test like this, the battery that was cycled at -5C had only slightly worse degradation than the room temperature batteries. To me that makes it pretty clear that an occasional charge cycle at -5C (or even lower) at a less than 1C rate of charge is not something to be worried about. Cycling at very high temperatures was actually far worse for the battery.

It is up to the user to decide what their requirements are, but for my use I am never going to need 2000+ 100% DOD cycles out of my batteries. In a good year, I am at about 100 nights of use, and most of those are at < 50% DOD, so even if I only get 20% of the rated cycles from my LiFePO4 battery, it will outlast my use. So in my case I don't sweat charging at -10C.

Now if this was an EV where the goal was to have a 200,000 mile lifetime, then the calculus would be different.

I think the most important thing to realize is that there are no black and white rules or limits. You can charge below freezing, you can run down to 0% SOC, you can cycle at high temperatures, it is all a trade off between usability and lifetime.
Got it. Appreciate you taking the time to clarify everything, FWC. Tried to look at the article in your link, but it was asking for registration info and a subscription fee. The article looked like it addressed my query perfectly.

I only had a cursory understanding of the ins and outs of LifePo4 just a month ago. Been processing a lot of info in the week or so since I built this LifePo4 battery pack. Still trying to put all these baselines and various risk factors into perspective. Thanks for all your help!

Dodgemahal

Idaho

New Member

Joined: 09/29/2019

View Profile



Posted: 04/27/21 08:45pm Link  |  Quote  |  Print  |  Notify Moderator

StirCrazy wrote:

Dodgemahal wrote:



Not putting a DC to DC charger in the system carries the risk of two things. Discharged lithiums can pull max current from your (non smart) alternator which will burn it up and possibly cause a fire. Ending up on the side of the road is a big possibility.


Lets clear this one up before it starts spreading as fact.

The only way this is going to happen is is some one took the fuse out of your charging line for your 7 way. Or if some person who didnt have a clue installed there own because it want a factory option and didnt put a fuse in.

I think most of this stems from the youtub video of a guy hooking a li pack directly to an altnator with large wires and started it up using an electric motor. no fuse now voltage loss and yes it did start stuf burning.

having said that I still would encourage the use of a LFP compatable DC to DC charger and proper wiring to provide the LFP battery its best charging.

Steve

Steve


Well you just reiterated what I was mentioning. The proper way to charge Lithiums (with the truck charging system)is with a DC to DC charger and not unregulated with a smart or dumb alternator. Because the lithium battery will absorb a lot of amps if you offer it up. Not sure what you cleared up though. Facts are what we both stated. So thank you. [emoticon]


Almost new to truck camping. Truck is a 2001 Dodge 3500 Dual rear wheel with a few performance mods. Camper is a 2005 Bigfoot 2500 9.6 with Lithiums. The trailer carries gear, one quad, two kayaks, two bicycles, and a 3700kw generator.

Siletzspey

Shedd, OR

Full Member

Joined: 01/24/2018

View Profile



Good Sam RV Club Member

Offline
Posted: 04/27/21 11:12pm Link  |  Quote  |  Print  |  Notify Moderator

Dodgemahal wrote:

... the lithium battery will absorb a lot of amps if you offer it up ...


Technically, voltage is pushed at the battery, and based on how many volts successfully reach the battery, the battery decides how many amps it wants to pull (at that voltage).

As hinted at above, Victron's burning-up alternator video is misleading in that it doesn't model in voltage drop, not to mention their pully gearing did not reflect what is typically installed in a truck, and they were running the alternator much slower than a truck at idle.

Lead-acid batteries typically want ~12.6VDC before they start pulling any current. Battery University says 12.6VDC +/- 0.3VDC.

LiFePO4 batteries typically want ~13.6VDC before they start pulling any current.

Factoring in voltage drop...

At ~13.6VDC from my 45A-capable Progressive Dynamics converter/charger with very short 4AWG wiring, my 100Ah x 2 BattleBorns at 50% SOC choose to pull ~4A total. At 13.6VDC, their thirst for current is minimal.

Assuming ~50 feet (one way) of 10AWG wire between your truck alternator thru the 7-pin to the battery, and an alternator putting out 14.4VDC, by definition you can only put a ~8 amp load on the wire before the voltage drops to 13.6VDC, which put another way means you can hook any number of LiFePO4s to such a 7-pin setup and you won't exceed ~8 amps of pull. No wires fry, no alternator burns out, etc.

Here is a link to the voltage drop calculation.

Assuming ~35 feet (one way) of 4AWG thru say Anderson connectors, a 46 amp load will drop the voltage to 13.6VDC, hence you won't exceed 46A of pull no matter how many LiFePO4 you hook up and how massive your alternator is.

Here is the updated calculation.

All that said to counter the myth that LiFePO4s always burn up wires and alternators if direct wired (unless the wires are really big and short!), DC-to-DC converters do so many valuable things, including countering voltage drop.

--tg

Durb

NW

Senior Member

Joined: 01/15/2016

View Profile



Good Sam RV Club Member


Posted: 04/28/21 08:13am Link  |  Quote  |  Print  |  Notify Moderator

I installed a 100AH Battle Born battery and Progressive Dynamics Lithium Convertor in my trailer. No maintenance, no removing the battery during the winter, no battery tender during the off season. I don't obsess about SOC and all the other stuff in this thread. I just ignore the battery and expect to do so for the next ten years. So far, the battery meets all my needs. So, for me, the lithium conversion was worth it.

jaycocreek

Idaho

Senior Member

Joined: 12/28/2013

View Profile


Offline
Posted: 04/28/21 08:52am Link  |  Quote  |  Print  |  Notify Moderator

Durb wrote:

I installed a 100AH Battle Born battery and Progressive Dynamics Lithium Convertor in my trailer. No maintenance, no removing the battery during the winter, no battery tender during the off season. I don't obsess about SOC and all the other stuff in this thread. I just ignore the battery and expect to do so for the next ten years. So far, the battery meets all my needs. So, for me, the lithium conversion was worth it.


That's pretty much how I feel also..While there are alot of things about the lifepo4 that interest me to totally understand it,none of it really matters in my day to day use..

It is just another battery except it can be drawn down 100% and it is totally lighter/charges way faster and does not need a 100% charge/ and the life cycles far exceed the others with caution towards charging below 32C..What's not to like..

Reply to Topic  |  Subscribe  |  Print Topic  |  Post New Topic  | 
Page of 8  
Prev  |  Next

Open Roads Forum  >  Truck Campers

 > Are lithium batteries worth the cost?
Search:   Advanced Search

Search only in Truck Campers


New posts No new posts
Closed, new posts Closed, no new posts
Moved, new posts Moved, no new posts

Adjust text size:




© 2021 CWI, Inc. © 2021 Good Sam Enterprises, LLC. All Rights Reserved.