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mohospinner 06-07-2021 09:25 PM

Replacing new Li-Ion batteries in Class A Motorhome
 
Hello fellow RVers,

I purchased (4) 12V 100aH Li-Ion batteries and want to make sure I don't damage anything.

Here is some information:

Year: 2020
Make: Fleetwood
Model: Pace Arrow LXE 38N (diesel pusher)
Inverter/Charger: Magnum MS2812
Controller: Magnum ME-ARC
Stock Batteries: (4) 6V lead acid batteries wired in series/parallel.
New Batteries: (4) 12V Ampere Time Li-Ion 100AH wired in parallel. (I watched many YouTube videos and read multiple reviews regarding these "Ampere Time" batteries).

My main concern is that I don't want to damage the electrical system, charging system, or alternator. I have read so many threads here and there and need more coherent answers. I have installed the Li-Ion batteries and changed the charging settings with the controller to constant charge/constant voltage (CC/CV) and the Li-Ion charging settings designated by the battery manufacturer. I have a 50A 240V outlet at my house that I plug into when the RV is here. I left it plugged in overnight with the 12V RV porch lights on and noticed before heading to bed that the lights were off and there was no house battery power in the RV (This was after many hours being plugged in to shore power). I disconnected the Li-Ion house batteries that night, re-connected them in the morning and things all looked normal and stable. Do you have any idea what would cause the house system to shut off?

My next question would be the alternator. I've read about DC-DC charging, upgraded alternators, and Battery Isolation Managers (Like this: https://battlebornbatteries.com/prod...ation-manager/) that time cycle the charge current from the alternator to the house batteries so they are not getting charged full time from the alternator. I'm confused with this. Which option is best? What do you use for this? I'm heading on a trip later this week and wondering if I should install a manual disconnect to shut down the charging from the alternator to the batteries before we head out to prevent charging from the alternator until I get this mess sorted out. (Update: I ordered the disconnects and will be installing on this week).

I'm also convinced I should probably install a Victron Battery Monitor to keep a close eye on things...

I appreciate any input and thank you in advance!

paul65k 06-07-2021 11:16 PM

Lots of questions here, I'll start with some of the easy ones first;

YES, you should get the battery monitor. Voltage is a poor way to measure capacity on a LiFePO4 battery as the discharge profile is very flat and then falls off the end of the earth and the Victron SmartShunt or BMS712 would be a great solution.

I think your choice to disconnect the alternator (regardless of what others may tell you) is a very prudent decision until you can figure which solution is best.

I personally believe that the DC-DC is the way to go and I did install dual Victron 30A chargers. The Li-BIM is also a good solution but the charging will be less as it works at 30A for 15 minutes and then is off for 20 minutes so if you do the math you are putting less charge back in the batteries while driving.... but that's not to say this is not a viable solution.

Your decision to wait until you have it completely figured out is wise and whichever solution you choose it should work out well for you.

Good luck and welcome to the next level....... Lithium batteries will change your life!:dance:

757driver 06-08-2021 10:42 AM

Your house system shut off because something in the batteries BMS was triggered to shut things down. Could have been over current from charging, cell or battery overvoltage etc. The next morning everything returned to normal so the bank could be reconnected. I would check your charge settings something may be wrong. You mentioned you have set up CC/CV charging. How long is your CV charge cycle? This cycle should be measured in minutes, not hours.

You mentioned getting a lithium BIM or a DC to DC charger. You have more control over a DC to DC charger, but the LI BIM works just fine. What BIM do you have presently? You may not get any alternator charging of your lithium bank in its present form.

vsheetz 06-08-2021 10:46 AM

Options for alternator charging:

Checking to see if the alternator draw is actually excessive and voltage is adequate to charge lithium - act or do nothing accordingly.

The LiBim is just a timed switch. So many minutes off, so many minutes on. The idea is to reduce the duty cycle. Depending on the actual draw and voltage, it may be a solution. I'm not a fan, ymmv.

A DC to DC charger is likely the best if solution needed. Select the proper size unit for the alternator and provides a proper lithium charge profile.

###

My experience with my DP motorhome and 600ah battery bank:

At low SoC the alternator draw is typically 40-45a - not excessive, and reduces as the bank charges. However the voltage is inadequate to bring the bank to a goodly charge level.

So a LiBim would not get the job done.

I've elected to do nothing, as my 1500w of solar typically charges well while traveling. If I do decide to add something, it would likely be a Victron DC to DC charger.

Imho. Ymmv.

vsheetz 06-08-2021 10:49 AM

Using CC/CV. What is the rebulk voltage set to? This is where the charger resumes charging after being silent. Suggest 13.0 bolts with lithium.

If set for lower voltage, as would be used with lead acid batteries, the lithium batteries could have been allowed to go to LVCO.

vsheetz 06-08-2021 10:51 AM

Yes. You need a batteru monitor such as Victron SmartShunt or BMV712. The flat discharge curve of lithium battery negates SoC estimation by voltage.

creativepart 06-08-2021 10:51 AM

I'm wondering about your description of your home shore power connection. You said "50amp 240v". But a 50 amp RV shore power connection is two 120v 50 amp legs. So, it's similar but certainly not the same thing at all.

Have you been using this home shore power set up from before you made this battery switch? Is it possible that the home shore power setup has damaged or tripped your on board charger?

vsheetz 06-08-2021 10:51 AM

Here's a pretty good article on the care and feeding of Lithium batteries.

https://www.solacity.com/how-to-keep...tteries-happy/

mohospinner 06-09-2021 09:35 AM

Quote:

Originally Posted by paul65k (Post 5782685)
Lots of questions here, I'll start with some of the easy ones first;

YES, you should get the battery monitor. Voltage is a poor way to measure capacity on a LiFePO4 battery as the discharge profile is very flat and then falls off the end of the earth and the Victron SmartShunt or BMS712 would be a great solution.

I think your choice to disconnect the alternator (regardless of what others may tell you) is a very prudent decision until you can figure which solution is best.

I personally believe that the DC-DC is the way to go and I did install dual Victron 30A chargers. The Li-BIM is also a good solution but the charging will be less as it works at 30A for 15 minutes and then is off for 20 minutes so if you do the math you are putting less charge back in the batteries while driving.... but that's not to say this is not a viable solution.

Your decision to wait until you have it completely figured out is wise and whichever solution you choose it should work out well for you.

Good luck and welcome to the next level....... Lithium batteries will change your life!:dance:

Thanks Paul65K,

Ok on the battery monitor. It seems like the logical thing to do and I have heard nothing but praise for Victron products.

I think I will disconnect the alternator until I go with the Victron DC-DC charger like you mentioned. You mentioned "Dual", can a single charger have enough power to charge my 400aH battery bank or do I need (2) DC-DC chargers?

I will submit a summary when I get this all sorted out.

Thanks again!

mohospinner 06-09-2021 09:40 AM

Quote:

Originally Posted by 757driver (Post 5783169)
Your house system shut off because something in the batteries BMS was triggered to shut things down. Could have been over current from charging, cell or battery overvoltage etc. The next morning everything returned to normal so the bank could be reconnected. I would check your charge settings something may be wrong. You mentioned you have set up CC/CV charging. How long is your CV charge cycle? This cycle should be measured in minutes, not hours.

You mentioned getting a lithium BIM or a DC to DC charger. You have more control over a DC to DC charger, but the LI BIM works just fine. What BIM do you have presently? You may not get any alternator charging of your lithium bank in its present form.

Thanks 757, I will check the CC/CV settings today or tomorrow. I currently have a stock BIM that was installed new in the coach and have no idea where it might be, but probably not going down the aftermarket BIM route as I would rather deal with the more effective DC-DC charging method. Thanks again.

mohospinner 06-09-2021 09:41 AM

Quote:

Originally Posted by vsheetz (Post 5783178)
Options for alternator charging:

Checking to see if the alternator draw is actually excessive and voltage is adequate to charge lithium - act or do nothing accordingly.

The LiBim is just a timed switch. So many minutes off, so many minutes on. The idea is to reduce the duty cycle. Depending on the actual draw and voltage, it may be a solution. I'm not a fan, ymmv.

A DC to DC charger is likely the best if solution needed. Select the proper size unit for the alternator and provides a proper lithium charge profile.

###

My experience with my DP motorhome and 600ah battery bank:

At low SoC the alternator draw is typically 40-45a - not excessive, and reduces as the bank charges. However the voltage is inadequate to bring the bank to a goodly charge level.

So a LiBim would not get the job done.

I've elected to do nothing, as my 1500w of solar typically charges well while traveling. If I do decide to add something, it would likely be a Victron DC to DC charger.

Imho. Ymmv.

Helpful info. Thank you Vince.

mohospinner 06-09-2021 09:42 AM

Quote:

Originally Posted by vsheetz (Post 5783182)
Using CC/CV. What is the rebulk voltage set to? This is where the charger resumes charging after being silent. Suggest 13.0 bolts with lithium.

If set for lower voltage, as would be used with lead acid batteries, the lithium batteries could have been allowed to go to LVCO.

I will check this later today or tomorrow and see what the settings are and modify if needed.

mohospinner 06-09-2021 09:46 AM

Quote:

Originally Posted by creativepart (Post 5783186)
I'm wondering about your description of your home shore power connection. You said "50amp 240v". But a 50 amp RV shore power connection is two 120v 50 amp legs. So, it's similar but certainly not the same thing at all.

Have you been using this home shore power set up from before you made this battery switch? Is it possible that the home shore power setup has damaged or tripped your on board charger?

It's the same 240V 14-50 outlet you would use with any larger coach or 5th wheel. (4 wires), 2 hots, 1 neutral, and 1 ground (240V between hots, 120V between hot/neutral or hot/ground). It's exactly the same.Thanks

mohospinner 06-09-2021 09:47 AM

:thumb:

Quote:

Originally Posted by vsheetz (Post 5783188)
Here's a pretty good article on the care and feeding of Lithium batteries.

https://www.solacity.com/how-to-keep...tteries-happy/


RichardE 06-09-2021 12:15 PM

To MoHo,

I recently worked with another Newell owner who installed a well known LiOn battery bank and used their CC/CV recommendations to the letter.

This setup was not treating his batteries kindly at all. When he challenged the CC/CV numbers from the battery maker, they quickly said that other setups may work better.

When you have a chance, please post your setup parameters. All of them. There are a few folks following this thread that can help you fine tune them to get the most out of that setup.

Specifically:
Charge current
Charge current time or trigger point to change to CV
CV voltage
CV trigger to turn off. Is it time, returned amps, or something else
What is your low battery cutoff for the inverter?

Are you using an external battery management system or depending upon the BMS internal to the batteries to protect them?

And lastly, how do you plan on using the battery bank? The reason I ask is that if you are a serious boondocker and need all the power available, then that will require a more aggressive charge and discharge setup. If you are a pedestal to pedestal traveler, then a less aggressive setup will work that should give much longer battery life.

And up front, I am not an alternator charge the LiOn guy. I know others are successful with it, but my bank is 1000 AHr, and would fry my alt in about an hour if it were trying to charge a low SOC situation.

757driver 06-09-2021 01:17 PM

Quote:

Originally Posted by vsheetz (Post 5783188)
Here's a pretty good article on the care and feeding of Lithium batteries.

https://www.solacity.com/how-to-keep...tteries-happy/

Overall a great article but I have issue with one paragraph.

“There is no sulphating, there is no equalizing, the absorb time does not really matter, you cannot really overcharge the battery, and the BMS takes care of keeping things within reasonable boundaries.”

Absorb time does matter…..a lot. Yes, you can overcharge a lithium battery and at a much lower voltage than one would think. A BMS should not be relied upon for controlling charging and discharging it should be used as a safe guard if your user settable parameters fail.

mohospinner 06-09-2021 05:57 PM

Quote:

Originally Posted by RichardE (Post 5784808)
To MoHo,

I recently worked with another Newell owner who installed a well known LiOn battery bank and used their CC/CV recommendations to the letter.

This setup was not treating his batteries kindly at all. When he challenged the CC/CV numbers from the battery maker, they quickly said that other setups may work better.

When you have a chance, please post your setup parameters. All of them. There are a few folks following this thread that can help you fine tune them to get the most out of that setup.

Specifically:
Charge current
Charge current time or trigger point to change to CV
CV voltage
CV trigger to turn off. Is it time, returned amps, or something else
What is your low battery cutoff for the inverter?

Are you using an external battery management system or depending upon the BMS internal to the batteries to protect them?

And lastly, how do you plan on using the battery bank? The reason I ask is that if you are a serious boondocker and need all the power available, then that will require a more aggressive charge and discharge setup. If you are a pedestal to pedestal traveler, then a less aggressive setup will work that should give much longer battery life.

And up front, I am not an alternator charge the LiOn guy. I know others are successful with it, but my bank is 1000 AHr, and would fry my alt in about an hour if it were trying to charge a low SOC situation.

Hi RichardE,

My batteries have a built in BMS and I'm controlling them with the Magnum ME-ARC controller to specify the charge settings.

I want to be flexible with my situation. We BoonDock from time to time and plug into park power also. So I'm guessing we are 70% park power and 30% BoonDocking.

Thanks,

Matt

mohospinner 06-09-2021 06:12 PM

1 Attachment(s)
Hi everyone. Thanks for your help so far. I have drawn up a diagram of my "proposed" install. Please take a look and let me know if I have designed this correctly. I am open to your input and looking forward to seeing your comments. Thanks-Moho

Attachment 331560

nvs4602 06-09-2021 06:29 PM

DC TO DC charger
 
Since my converter is not compatible with lifepo4 batteries.
I going to us a DC to DC charger to charge the battery from the alternator and the converter both. To do this I will install a SPDT relay with the converter connected to the normally closed pole. And the alternator connected to the normally open contact.


https://smile.amazon.com/dp/B08F2G1J...ing=UTF8&psc=1

mohospinner 06-09-2021 07:38 PM

Quote:

Originally Posted by mohospinner (Post 5785234)
Hi RichardE,

My batteries have a built in BMS and I'm controlling them with the Magnum ME-ARC controller to specify the charge settings.

I want to be flexible with my situation. We BoonDock from time to time and plug into park power also. So I'm guessing we are 70% park power and 30% BoonDocking.

Thanks,

Matt

RichardE,

I will post initial parameters tomorrow and see how it works. I still don't have the DC-DC charger or Smart Shunt. Placing order soon.

153stars 06-09-2021 09:02 PM

Wrong post

Caymanedge 06-10-2021 10:12 AM

I installed LifePO4 is a similar set-up, same Magnum MS2812 and utilized the ARC control. Set-up is easy and everything is working great. I wouldn't hesitate to do it again.
I also replaced my existing battery isolator with the Battle Born LI-BIM unit to protect my alternator. Connections were simple, but getting everything positioned properly to connect was a challenge. I had to make a bracket to mount it and a few extension cables.

mohospinner 06-10-2021 05:06 PM

Hi Richard,

Here are my parameters:

AC IN: 50A
VAC Dropout: 80A
Battery Type: CC/CV
Max Charge Rate: 100%
Max Charge Amps: 200
CV Charge Volts: 14.6
CV Done Time: 1.3 Hours (20 min per battery x 4 batteries)
Recharge Volts: 13.8
Low Battery cutoff: 11 Volts (manufacturer says 10.8, but I opted for the .2 buffer)

It looks like everything is controlled by the CC/CV settings and cannot be altered unless I'm missing something. The parameters were set by "Ampere Time" on a printed card that was included with each battery.

Also curious as to what 757Driver says about the parameters I set. I installed the battery disconnect and am heading on a 5 hour drive tomorrow. I think I will just shut the house batteries off while I drive unless you all think otherwise? This is to avoid any conflicts with the alternator and I'm also still waiting for my Victron DC-DC charger and smart shunt to arrive. Thoughts?

mohospinner 06-10-2021 05:08 PM

Caymanedge,

Thank you.

Could you post your controller parameters for us to see? Also include the information about your battery bank. Thanks!

Caymanedge 06-11-2021 04:48 AM

4x170ah LifePO4
I am not near it to get the charging parameters right now. The only thing that jumps out at me from your list is the recharge volts. I believe mine settle at 13.4.

757driver 06-11-2021 08:52 AM

Quote:

Originally Posted by mohospinner (Post 5786471)
Hi Richard,

Here are my parameters:

AC IN: 50A
VAC Dropout: 80A
Battery Type: CC/CV
Max Charge Rate: 100%
Max Charge Amps: 200
CV Charge Volts: 14.6
CV Done Time: 1.3 Hours (20 min per battery x 4 batteries)
Recharge Volts: 13.8
Low Battery cutoff: 11 Volts (manufacturer says 10.8, but I opted for the .2 buffer)

It looks like everything is controlled by the CC/CV settings and cannot be altered unless I'm missing something. The parameters were set by "Ampere Time" on a printed card that was included with each battery.

Also curious as to what 757Driver says about the parameters I set. I installed the battery disconnect and am heading on a 5 hour drive tomorrow. I think I will just shut the house batteries off while I drive unless you all think otherwise? This is to avoid any conflicts with the alternator and I'm also still waiting for my Victron DC-DC charger and smart shunt to arrive. Thoughts?

Here are my thoughts.

CV charge volts- for normal day to day charging I would set this at 14.2v. This voltage will fully charge your lithium battery bank. Since your batteries have balance boards about once a month set this to 14.6v and let the balance boards do their thing. I have read where the more lithium batteries are balanced the more they go out of balance and need balancing.

CV done time- this goes hand in hand with balancing. The only reason for done time is to let the balance boards do their thing. Set this to the 1.3 hours when you put the CV voltage up to 14.6v, otherwise set it to 0.1-0.2 hours.

Recharge volts- once again it shows that the battery manufacturers don’t have a clue as to what they are talking about. A recharge voltage of 13.8v will keep your lithium battery at 100% SOC which is harmful. Once the charger switches off at 14.2v or 14.6v (as programmed) it will switch back on within seconds as the voltage drops to 13.8v and start the charge cycle all over again. For the thousands of cycles you will get out of your lithium bank let it cycle and set this to 13.0v.

Low battery cutoff- 10.8v or 11.0v is a good LBCO for lead acid batteries but is too low for lithium. Once a lithium battery hits about 12.0v it is at a very low SOC. I would set the inverter’s LBCO to 12.2v and make sure the inverter is taken off line prior to the lithium BMS activating.

mohospinner 06-11-2021 06:35 PM

Don,

Very Helpful! Thanks so much. I just changed the settings (as per your suggestions) and will see how it works out.

I had the batteries plugged in to shore power last night with no issues, so I guess I can scratch the DC cut-off problem off the list. Now I'm just waiting for the Victron DC-DC charger and the smart shunt to arrive in the mail. Everything seems to be good so far and I'm happy with converting to Lithium. Yesterday, I had the DC system and inverter system running off the Li-Ion batteries (without the shore power plugged in) and the voltage was very stable (even with getting the fridge down to temp and drawing up to 12 amps AC). Today we traveled 6 hours to our destination. I kept the house battery disconnect switch off (just to avoid alternator issues until the Victron system is installed).

Once I get the Victron equipment installed, I will post pictures and summary. Thanks again for your advice.

Best,

Matt

757driver 06-11-2021 10:30 PM

Quote:

Originally Posted by mohospinner (Post 5787902)
Don,

Very Helpful! Thanks so much. I just changed the settings (as per your suggestions) and will see how it works out.

I had the batteries plugged in to shore power last night with no issues, so I guess I can scratch the DC cut-off problem off the list. Now I'm just waiting for the Victron DC-DC charger and the smart shunt to arrive in the mail. Everything seems to be good so far and I'm happy with converting to Lithium. Yesterday, I had the DC system and inverter system running off the Li-Ion batteries (without the shore power plugged in) and the voltage was very stable (even with getting the fridge down to temp and drawing up to 12 amps AC). Today we traveled 6 hours to our destination. I kept the house battery disconnect switch off (just to avoid alternator issues until the Victron system is installed).

Once I get the Victron equipment installed, I will post pictures and summary. Thanks again for your advice.

Best,

Matt

Matt,

You are welcome. Once I got home to look at my settings (memory not as good as I thought) you could bring your LBCO down to 12.0v instead of 12.2v and have plenty of protection.

Enjoy your new batteries. :thumb:

RichardE 06-12-2021 10:51 AM

Matt,

Sorry for the late reply, traveling and spotty interweb to blame.


Anyway, I totally agree with 757 that your recharge voltage is way too high and that will keep your batteries at 100% SOC, the charger will stay on almost all the time, and that is not good for the LiPo. This was the main issue with the Newell owner that I worked with.

Also good recommendations on LBCO and recharge voltage settings from 757.

I do prefer, but this is not the gospel, that the end charge be set up to stop on return amps. Your ME-ARC is capable of this but you may need to add the BMK (battery monitor kit) to access the capability. As you know the amps that flow into the battery bank when charging decrease as the bank approaches full charge. By setting the charge to end when a certain amperage is reached instead of a fixed time you are “listening” to the batteries to know when to end the cycle. Conventional wisdom is to end the charge at 5% of the bank size. So if you have 4 100aHr batts, then set the charge to end when the charger decreases to 20 amps.

I also prefer to float the bank instead of cycling it repeatedly. BB recommends 13.6 as the float. I keep mine at 13.4, but I do not have BB batteries. Again, this is not the LiPo gospel.
You may or may not achieve 100%SOC using float. If you don’t, and you know you are going to boonie for a couple of days, then initiate a full charge manually using the ME-ARC.

I am going to recommend a simple test that will give you a “practical baseline” for your new bank. Sometime in the future you will want to know if you have lost capacity. The test is simple. Turn on the inverter, reset the amp hour out counter, turn off the 120v breaker that feeds the inverter. Run off batteries that way until the LBCO turns the inverter off. You will now know just how much juice the bank will provide before you must recharge. This may or may not match the nameplate, but it doesn’t matter. You are collecting data on what your system provides using the charge and low cutoff parameters.

I tend to be rather conservative in setting up the charge/discharge parameters. After 6 years my 1000aHr bank still has over a 1000aHr usable. That is only a data point of one, but it works for me. If you really want to fine tune your bank, there is an interesting little experiment you can run if you care to. The overall idea is to “listen” to the batteries, and they will tell you what they like. The experiment is to collect data from each individual battery while charging to 100% SOC, and to collect voltages again from each battery whiled discharging to about 5% SOC. Why do this? I have read virtual fist fights posted by LiPo “experts” arguing over 0.01 volts. Oh horse hockey. Unless you are using a NIST traceable volt meter, who has instrumentation to measure absolute voltage. And who cares? After all, your charger is going to charge according to the voltage it measures. That includes all the unique variability in YOUR system.

So back to the experiment. If you will take the time to plot the voltage of the individual cells and the charger voltage as the bank approaches 100% SOC against time, you will see the sharp upward rise start. Compare the battery voltages, take the highest one, and note the charger voltage. You now know, looking at your charger voltage exactly where you are on the sharply rising curve. You can decide how far up that curve you want to go. Now do the same graph for discharging the bank. You can see where the voltage starts to drop. You can use that part of the curve to know where to set the LBCO on your inverter.

Using the curves generated by YOUR batteries, you have confidence in where to set the charge and discharge parameters instead of looking at 100’s of LiPo curves on the interweb and trying in 0.1 volts what is safe. Depending on how risky you want to be you can decide how far up and down the steep curves you want to operate. I stay pretty close to the flat part of the curve to maximize the battery life, but I never come close to using my 1000aHR, so the size of one’s bank and the needed use may dictate you operate further up and down the curves.

I hope this helps, and sorry if it was TMI.

mohospinner 06-13-2021 11:11 PM

Hi Richard,

Wow! Thank you for the plethora of information. This is great and I am looking forward to conduct a (certified) "RichardE" test :rofl: . However, we did put the batteries to our own tests this weekend and they really performed outstanding. We had coffee makers going, a tea kettle, a friend with a trailer that needed power, portable tool battery chargers, and basically everything you could throw at them and they did not disappoint! I will send you a note when I complete the "RichardE" test. Thanks again.

mohospinner 06-13-2021 11:18 PM

Just a random question here...Regarding the DC-DC charger: All my Victron equipment is shipping en route and I'm still thinking about the existing alternator charging system for the house batteries. I'm <ASSUMING:facepalm:> that I need to disconnect a wire from the alternator that currently charges the house batteries? Or does it not matter since the DC-DC charging will take over the charging? I have not found any viable information regarding this question. Thanks guys. You all are very helpful and I appreciate your input.

twinboat 06-14-2021 12:07 AM

Quote:

Originally Posted by mohospinner (Post 5790607)
Just a random question here...Regarding the DC-DC charger: All my Victron equipment is shipping en route and I'm still thinking about the existing alternator charging system for the house batteries. I'm &lt;ASSUMING:facepalm:&gt; that I need to disconnect a wire from the alternator that currently charges the house batteries? Or does it not matter since the DC-DC charging will take over the charging? I have not found any viable information regarding this question. Thanks guys. You all are very helpful and I appreciate your input.

There is no wire on the alternator that charges the house battery.
The alternator only connects to the chassis battery, and charges that.

There is what's called a charging or bridging solenoid or relay that connects the chassis battery to the house battery when conditions are right.
That needs to be disabled.

mohospinner 06-14-2021 09:56 AM

Thanks TwinBoat,

So by disabling this relay it will also disable the battery boost switch on the dash or is that something entirely different?

twinboat 06-14-2021 10:59 AM

Quote:

Originally Posted by mohospinner (Post 5791095)
Thanks TwinBoat,

So by disabling this relay it will also disable the battery boost switch on the dash or is that something entirely different?

Yes it will disable the boost switch, unless its a seperate wire to the solenoid. Then you can leave that on, only disabling the solenoid controler, if a seperate item.

WeaverBeaver 10-07-2021 08:51 PM

Hello,thank you all for very good information. I'm just about to complete a 1200AH Lifpo4 conversion this week with almost the same components mentioned.....Is it possible to keep the battery boost function with this dc-dc charging set-up? Would removing the ignition wire circuit and leaving the switch wire only activate the connection while holding down boost button?


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