RV News RVBusiness 2021 Top 10 RVs of the Year, plus 56 additional debuts and must-see units → ×
 


Reply
 
Thread Tools Display Modes
 
Old 11-08-2020, 11:37 AM   #1
Member
 
Thorne's Avatar
 
Join Date: Sep 2020
Location: SF Bay Area
Posts: 42
Any good guides to replacing AGM house & starter with LiFeP04?

We've got a fairly stock 2011 SMB RB110S build -- all electric, no back heater, 6 gal hot water heater, unknown inverter size.

The two house batteries had enough dust to be original but certainly need replacement anyway. The starter AGM battery is relatively new but I can replace it if that's what's needed to have the alternator charging work properly.

Unknown: Inverter size / rating. Also unknown is how alternator charging works (direct to house bank, via the starter wired in series, or via an isolator that works when ignition is off, etc). Ditto for solar charging to house bank.

I know I'll need an updated solar controller / charger for whatever LiFeP04 house batteries (or battery) I install. Should I keep the current Zamp charger for the starter battery and put in the new LiFeP04-rated charger next to it for the new house battery(ies)?

Or is it easier to replace both starter and house batteries with LiFeP04 batteries, then figure out how to avoid over-charging the starter battery from the alternator?

I'd like to just put in one 100ah LiFeP04 battery to replace the old 2x 62ah AGM marine deep cycle batteries. We're not heavy power users ... yet. ;-)

Current controllers and fuses. Ignore the asian text sticker - humor from the PO.
__________________

__________________
------------
2011 Freightliner 2500 Sportsmobile RB110S, all electric, 150k
Thorne is offline   Reply With Quote
Old 11-08-2020, 12:07 PM   #2
Senior Member
 
Join Date: Nov 2016
Location: FL and VA
Posts: 1,126
Garage
You will need to figure the out wiring system and how the alt charges the house batteries because you should add a DC to DC charger as well as a shore power charger.

Is the inverter also your charger?

Scalf77 will hopefully be along to offer recommendations.
__________________

__________________
Chris
2008 GMC 3500 Quigley Weldtec 4x4 Savana SMB
2006 BMW HP2 Enduro
marret is online now   Reply With Quote
Old 11-08-2020, 01:29 PM   #3
Senior Member
 
Join Date: Aug 2019
Location: Elk Grove, CA
Posts: 210
There are a lot of complex issues, especially with respect to alternator charging of LiFePO4 batteries. This may give you some insight:

https://www.winnieowners.com/forums/...on-359190.html
__________________
Bob
2005 E350 Super Duty Ext Wheelchair Van
2002 Itasca 35U Motorhome
BCam is offline   Reply With Quote
Old 11-08-2020, 09:02 PM   #4
Senior Member
 
Join Date: Nov 2019
Location: Denver Colorado
Posts: 299
You will need to be able to input a algorithm into you controller that works for the Lithium batteries. If your controller doesn't have programmable charging capabilities you won't get the full use/life from your lithium batteries. I wouldn't use a lithium battery for a starter battery. They don't like the cold and they are made more for big discharge- recharge cycles. Your starter battery is always being topped off from the alternator, it never really gets discharged much.
Lilnuts2 is offline   Reply With Quote
Old 11-10-2020, 09:12 AM   #5
Senior Member
 
Scalf77's Avatar
 
Join Date: May 2007
Location: Beaverton, OR
Posts: 1,796
It appears your shore charger is a Tripp-lite RV1512UL inverter/charger which basically only has a Gel & Wet cell setting. This would make this a good choice to be replaced with a unit that supports a lithium and/or programmable charge settings.

I would expect that your that your build uses a Blue Sea ACR for the alternator to house charging. So you also would need to look for a new solution for alternator charging of the house battery.

Now I would start looking at lithium batteries and decide which manufacturer that you are interested in going with. This is important as each manufacturer should have the settings that they want for their battery. This way when you look for new charging devices that will meet the the charging parameters of the battery you go with.

Now when choosing a lithium battery you have another specification to be worried about. Many of the internal BMS batteries, are limited in current discharge by the size of the internal FET's used to protect the lithium batteries. This many times is specified around 100 amps. So if choosing a 100 Ah battery you might have a discharge capability 100 amps continuous (200 Amp Surge). This becomes important if you are a big inverter uses as it will be your largest current user. 2000 watt / 12 volts = 167 amps. This would mean that you would need two 100 Ah batteries in parallel to use your inverter to full capacity. So check your choices and make sure you can support your chosen system. If you choose a external BMS you will need to check that specification also.

For the alternator charging you will have to change the ACR solution. A common solution is a DC to DC charger, like Sterling Power or KISAE DMT1250. There are many more on the market and it is growing. This will enable you to take alternator power and charge your lithium battery with the correct parameters for the battery.

A simpler solution would be much like your ACR, but has additional capabilities like Precision Circuits Inc LI-BIM or Battery Isolation Manager. The BIM limits the charging of the lithium battery to around 80% to prevent over charging. Take this into account in your power usage calculations.

If moving to a large lithium bank a second alternator with a multi-stage regulator would be a better choice.

Most solar controllers also now support lithium but again, you want to make sure that they support the battery of your choice. Some of the DC to DC chargers available have a solar input also, making one unit for both solar and alternator charging.

I do cover some of these devices in the Battery Isolators, Separators, Switches & More (updated 2020) post starting on post #5

Many Inverter/Chargers now support lithium. I will throw in a shameless plug for a New in the Box Magnum MS2000 I have available.

hope this helps.

-greg
Scalf77 is offline   Reply With Quote
Old 11-15-2020, 02:16 PM   #6
Member
 
Join Date: Sep 2019
Posts: 75
Greg nailed it.

Isn’t a drop in solution but lithium is a way better technology!!
winnievan is offline   Reply With Quote
Old 11-15-2020, 03:22 PM   #7
Senior Member
 
Twoxentrix's Avatar
 
Join Date: Mar 2015
Location: Annapolis, Maryland
Posts: 1,856
Garage
Thorne - There is middle ground between AGM & LiFeP04 batteries...Carbon Foam.

The Carbon foam offers around 3500 cycles at 50% DOD, and 1000 cycles at 80% DOD... crudely stated, that's 1/2 of what Lithium's claims, but about 3 times more than an AGM.
The difference in using the Carbon foam is its more affordable than Lithium & its essentially a "drop in" (you don't have to upgrade all of your electronic support infrastructure to accommodate Lithium).

https://www.amazon.com/exceptional-p.../dp/B078GKKN17 (Just included as reference - can get a better price, less the huge shipping expense here)

https://oceanplanetenergy.com/advanc...asis-group-31/

https://coastalclimatecontrol.com/in...g-reveals.html

https://www.pacificnwboatertested.co...-really-better

***Just an alternative worth mentioning.
__________________
TwoXentrix
"AWOL"
Twoxentrix is online now   Reply With Quote
Old 11-15-2020, 07:31 PM   #8
Junior Member
 
Join Date: May 2016
Posts: 4
This becomes important if you are a big inverter uses as it will be your largest current user. 2000 watt / 12 volts = 167 amps. This would mean that you would need two 100 Ah batteries in parallel to use your inverter to full capacity.

Wouldn’t a 2000 watt inverter be at 120 volts, so 2000 watt/120 volts= 16.7 amps?
Viajero is offline   Reply With Quote
Old 11-15-2020, 07:37 PM   #9
Senior Member
 
Scalf77's Avatar
 
Join Date: May 2007
Location: Beaverton, OR
Posts: 1,796
Quote:
Originally Posted by Viajero View Post
Wouldn’t a 2000 watt inverter be at 120 volts, so 2000 watt/120 volts= 16.7 amps?
Sure, that would be what it puts out. But, it has to get that power from the 12 DC system. The inverter takes DC battery power and creates AC Power, so 2000 watts / by 12 volts would be 167 amps. Actually a little higher with conversion cost.

-greg
Scalf77 is offline   Reply With Quote
Old 11-15-2020, 07:44 PM   #10
Senior Member
 
Join Date: Aug 2019
Location: Elk Grove, CA
Posts: 210
Quote:
Originally Posted by Scalf77 View Post
Sure, that would be what it puts out. But, it has to get that power from the 12 DC system. The inverter takes DC battery power and creates AC Power, so 2000 watts / by 12 volts would be 167 amps. Actually a little higher with conversion cost.

-greg


Greg is correct but, just to be clear, a 2000 watt converter only puts out 2000 watts and consumes 167+ amps when you're running something that uses that many watts. And most inverters' rating is based on their peak wattage capacity, not their steady state wattage capacity.
__________________

__________________
Bob
2005 E350 Super Duty Ext Wheelchair Van
2002 Itasca 35U Motorhome
BCam is offline   Reply With Quote
Reply

Thread Tools
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

Powered by vBadvanced CMPS v3.2.3
Disclaimer:

This website is not affiliated with or endorsed by Sportsmobile SIP or any of its affiliates. This is an independent, unofficial site.


All times are GMT -6. The time now is 05:10 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
×