RV Trip Planning Discussions

Go Back   iRV2 Forums > RV SYSTEMS AND TECHNOLOGIES FORUMS > Going Green
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
Reply
 
Thread Tools Search this Thread Display Modes
 
Old 07-30-2020, 05:09 PM   #15
Senior Member
 
Itinerant1's Avatar
 
Join Date: May 2017
Location: Itinerant
Posts: 552
Let's not forget about the ability to go for long periods in a partial SOC with lfp and as mentioned still use high draw items with no ill effects. I've pulled 235a at 36% soc inverting at 12.2v, use the coffee maker or microwave pulling 85-147a at 25% soc inverting at 12.5-12.6v early morning and still let solar charge to 65-70% soc and do it over and over and over and over till finally solar catches to up fully charge the bank.
__________________

__________________
2010 Carriage Cameo F34CK3
1,280w solar, 12v500ah
Itinerant1 is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 07-30-2020, 08:20 PM   #16
Senior Member
 
Join Date: May 2017
Posts: 848
Quote:
Originally Posted by twinboat View Post
What's not " Safe " about drawing lead acid batteries down to 10% or 20% charge ?
Not a safety issue, but it hurts their life expectancy as you point out.

The way lead acid batteries are tested for "amp hours" is they are discharged down to 1.75 volts/cell (10.5 volts for a 12V battery). This is well below the recommended discharge amount of 50%. This is also well below the point of when most inverter will shut down (typically >11 volts).

Lithium has a different "rate of discharge" so with the same inverter load, it likely will keep that inverter running longer.
__________________

__________________
Retired. 31 year of automotive engineering for one of the Detroit 3, specializing in Powertrain Control Systems.
theoldwizard is offline   Reply With Quote
Old 07-31-2020, 06:39 AM   #17
Senior Member
 
Winnebago Owners Club
Workhorse Chassis Owner
Join Date: Nov 2018
Posts: 718
Quote:
Originally Posted by theoldwizard View Post
Not a safety issue, but it hurts their life expectancy
If you view a LA battery as a mechanism for storing and retrieving amp hours (which is their primary purpose), and you get nearly the same amount of amp hours over their life whether you take them 20%, 50% or 80% at a time, then what is being "hurt"? You're getting all the performance you paid for, so what's the economy in not using the capacity they offer?

Mark B.
Albuquerque, NM
Mark_K5LXP is offline   Reply With Quote
Old 07-31-2020, 11:28 AM   #18
Senior Member
 
Join Date: Sep 2017
Location: Northern California
Posts: 613
Quote:
Originally Posted by theoldwizard View Post
Not a safety issue, but it hurts their life expectancy as you point out.

The way lead acid batteries are tested for "amp hours" is they are discharged down to 1.75 volts/cell (10.5 volts for a 12V battery). This is well below the recommended discharge amount of 50%. This is also well below the point of when most inverter will shut down (typically >11 volts).

Lithium has a different "rate of discharge" so with the same inverter load, it likely will keep that inverter running longer.
I agree fully, and here's an interesting fact. The popular Battle Born 100 AH LFP battery has to be drawn down to 8.8V to get at the full AH capacity. BB tests their batteries to have at least 102 AH when drawn down to 2.2V per cell (8.8V) before they leave the factory. That's the bad news, at least for BB.

The good news is that even with the BB LFP, voltage does not start dropping significantly until SOC is below 10%. With lighter loads voltage won't become a problem until below 5% SOC. With AGM voltage can become problematic at 30% SOC with heavier loads and it can handle only light loads at 20%.
__________________
2020 GMC Denali 2500HD Crew 4X4 Gas 6.6L Rockwood 8280WS (30' 5th)
600W solar; 300AH LFP battery, 900W PSW inverter
Coming soon: +400W solar & NovaKool RFU9000 fridge
hclarkx is offline   Reply With Quote
Old 07-31-2020, 11:37 AM   #19
Senior Member
 
Winterbagoal's Avatar
 
Join Date: Mar 2017
Location: Sarnialabad, Peoples Republik of Canuckistan
Posts: 1,399
Quote:
Originally Posted by Itinerant1 View Post
Let's not forget about the ability to go for long periods in a partial SOC with lfp and as mentioned still use high draw items with no ill effects. I've pulled 235a at 36% soc inverting at 12.2v, use the coffee maker or microwave pulling 85-147a at 25% soc inverting at 12.5-12.6v early morning and still let solar charge to 65-70% soc and do it over and over and over and over till finally solar catches to up fully charge the bank.
We haven't beat ours up like that yet, but I fully expect our usage to be similar with similar results. Pricey? Yes, but worth it, if you off grid even a little bit.
__________________
2018 (2017 Sprinter Cab Chassis) Navion24V + 2016 Wrangler JKU (sold @ ????)
2016 Sunstar 26HE, V10, 3V, 6 Speed (sold @ 4600 miles)
2002 Roadtrek C190P (sold @ 315,000kms)
Winterbagoal is offline   Reply With Quote
Old 07-31-2020, 11:38 AM   #20
Senior Member
 
Join Date: Sep 2017
Location: Northern California
Posts: 613
Quote:
Originally Posted by Mark_K5LXP View Post
If you view a LA battery as a mechanism for storing and retrieving amp hours (which is their primary purpose), and you get nearly the same amount of amp hours over their life whether you take them 20%, 50% or 80% at a time, then what is being "hurt"? You're getting all the performance you paid for, so what's the economy in not using the capacity they offer?

Mark B.
Albuquerque, NM
True. You get shorter cycle life with the deeper discharge and much longer cycle life with a shallow discharge. But, sticking with a shallower discharge greatly reduces the functionality of the battery. A dry camper has to be a very light electrical energy user to stay out very long and not accept a deeper discharge.

To make a shallow discharge work with LA, one must carry a lot of battery weight ... and invest more. The alternative, a deeper discharge and days between re-charges, means less AGM battery life. With the cost of LFP as little as twice the cost of an AGM, LFP is a no-brainer. Four times the life for twice the money, half the weight, greater discharge freedom, less solar capacity, and more make LFP an easy choice.
__________________
2020 GMC Denali 2500HD Crew 4X4 Gas 6.6L Rockwood 8280WS (30' 5th)
600W solar; 300AH LFP battery, 900W PSW inverter
Coming soon: +400W solar & NovaKool RFU9000 fridge
hclarkx is offline   Reply With Quote
Old 07-31-2020, 11:51 AM   #21
Senior Member
 
Winterbagoal's Avatar
 
Join Date: Mar 2017
Location: Sarnialabad, Peoples Republik of Canuckistan
Posts: 1,399
Quote:
Originally Posted by hclarkx View Post
True. You get shorter cycle life with the deeper discharge and much longer cycle life with a shallow discharge. But, sticking with a shallower discharge greatly reduces the functionality of the battery. A dry camper has to be a very light electrical energy user to stay out very long and not accept a deeper discharge.

To make a shallow discharge work with LA, one must carry a lot of battery weight ... and invest more. The alternative, a deeper discharge and days between re-charges, means less AGM battery life. With the cost of LFP as little as twice the cost of an AGM, LFP is a no-brainer. Four times the life for twice the money, half the weight, greater discharge freedom, less solar capacity, and more make LFP an easy choice.
And, I would add, the better brands of LFP are mostly idiot proof, in that, it's harder to get past the BMS "sentinel" and screw them up, unlike FLA/AGM.
__________________
2018 (2017 Sprinter Cab Chassis) Navion24V + 2016 Wrangler JKU (sold @ ????)
2016 Sunstar 26HE, V10, 3V, 6 Speed (sold @ 4600 miles)
2002 Roadtrek C190P (sold @ 315,000kms)
Winterbagoal is offline   Reply With Quote
Old 07-31-2020, 11:56 AM   #22
Senior Member
 
Itinerant1's Avatar
 
Join Date: May 2017
Location: Itinerant
Posts: 552
Quote:
Originally Posted by Winterbagoal View Post
We haven't beat ours up like that yet, but I fully expect our usage to be similar with similar results. Pricey? Yes, but worth it, if you off grid even a little bit.
This winter will be our 5th winter using it like that. But we are fulltimers that mostly boondock traveling. Since having the system installed in April 2016 and living off of 500ah lfp/ 1,280w solar it breaks down as 1,448 days boondocked out of 1,568 days.
Itinerant1 is offline   Reply With Quote
Old 07-31-2020, 02:31 PM   #23
Senior Member
 
Winterbagoal's Avatar
 
Join Date: Mar 2017
Location: Sarnialabad, Peoples Republik of Canuckistan
Posts: 1,399
Quote:
Originally Posted by Itinerant1 View Post
This winter will be our 5th winter using it like that. But we are fulltimers that mostly boondock traveling. Since having the system installed in April 2016 and living off of 500ah lfp/ 1,280w solar it breaks down as 1,448 days boondocked out of 1,568 days.
We're small fry/amateurs compared to you.

Our system is 200Ah Relions (cold charging option) + 300W Zamp solar.
But it does handle most of the individual tasks you mentioned, and that works fine for us.
__________________
2018 (2017 Sprinter Cab Chassis) Navion24V + 2016 Wrangler JKU (sold @ ????)
2016 Sunstar 26HE, V10, 3V, 6 Speed (sold @ 4600 miles)
2002 Roadtrek C190P (sold @ 315,000kms)
Winterbagoal is offline   Reply With Quote
Old 07-31-2020, 10:49 PM   #24
Senior Member
 
Join Date: Sep 2017
Location: Northern California
Posts: 613
Quote:
Originally Posted by Winterbagoal View Post
And, I would add, the better brands of LFP are mostly idiot proof, in that, it's harder to get past the BMS "sentinel" and screw them up, unlike FLA/AGM.
Good point, and that screw-up you refer to can be quite disastrous. There are videos on youtube of lead-acid batteries exploding. Most I've seen are the result of putting a simple automotive charger on them at a higher current and forgetting it's there. Though I suspect that a short-circuit could make a lead-acid battery come apart. I would think the lower internal resistance of an AGM would make it more dangerous than a flooded cell ... though maybe it has less acid in it making it less dangerous. The bottom line is that IMHO an LFP is safer than an AGM because it has a BMS. Nobody has ever build an AGM with a BMS I suspect, but somebody should.
__________________

__________________
2020 GMC Denali 2500HD Crew 4X4 Gas 6.6L Rockwood 8280WS (30' 5th)
600W solar; 300AH LFP battery, 900W PSW inverter
Coming soon: +400W solar & NovaKool RFU9000 fridge
hclarkx is offline   Reply With Quote
Reply

Tags
battery



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
House battery/chassis battery/charging and start assist question Rookie RVer Class C Motorhome Discussions 5 06-06-2020 07:02 PM
Battery & Battery Disconnect Question(s) and advice needed LCDRAKAllen Newmar Owner's Forum 16 12-15-2015 08:31 AM
Another battery question - chassis battery and inverter cvbdsl Class A Motorhome Discussions 12 04-06-2015 04:30 PM
Battery Question answered, now I have a solar panel question! Lkraus3 Vintage RV's 8 02-21-2011 11:06 AM
"Fresh" water question, & Inverter/Battery question Dagwood_73 Boondocking 7 07-29-2005 01:15 PM

» Featured Campgrounds

Reviews provided by


All times are GMT -6. The time now is 02:52 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
×