Questions about AGM -> LFP

[Urlauber]

Thank you, I wish mine were labeled as nicely!

[@Michael]

Originally Posted by Urlauber

So... that's the big (converter) question for me here - what is the worst thing that could happen if I would use the existing WF-8955-PEC on a single 100Ah LFP battery.

From the WFCO manual, it looks like it would bulk charge at 55amps to 14.4v, hold that for either 4 hours or until current drops to less than 5 amps. It will then drop to 13.6v absorption for 44 hours, then drop to 13.2 float.

https://wfcoelectronics.com/theory-of-operation/
https://wfcoelectronics.com/wp-conte...ies-Manual.pdf

• The 14.4V should be OK if the current drops to less than 5 amps (less than 5A parasitic loads)
• The 13.6v absorption shouldn't hurt either.
• The 13.2 float is low - the LiFePo4 will be significantly discharged at that voltage. Your solar should still charge though, so you should never see 13.2v.

Is the WFCO charger on a separate breaker? If so, and if it were mine, I'd buy the cheapest Victron battery charger (Victron IP65 BlueSmart) that can charge at about 10 - 15 amps and set it up with a proper lithium profile. That'll cover you any time you are plugged in. I'd shut the breaker that powers the WFCO charger off and only flip it on when I really needed a 50amp fast charge, and shut it back off when the lithium is charged. If you don't think you'll even need 50A charge, then disconnect the WCFO completely.

[Urlauber]

From what I gather, the converter will only come into play when I am plugged in or the generator runs. Both will be happening rarely - most of the places I stay don't have hookup, and the solar panels should be able to maintain our meager energy needs so no genny necessary.

Given that, would you still try to isolate the converter and add another charger? It sounds like the WFCO wold not damage the battery, it would only not optimally charge it. And again, NORMALLY I would not use the converter. All that said, adding a switch to prevent the converter from charging the LFP when I don't want it (like when running the genny just for A/C) sounds like a good option.

Been looking at batteries that come with some monitoring app to easily see the SOC and cell voltage on the existing BMPro screen. This one is heavily promoted by Amz... but it seems like a candidate. Not a brand name for sure, so it could be a bit risky.

Also, I was hoping to install such a battery in one of the two then available battery brackets underneath the car... Is that a terrible idea? I could probably fit them in some sort of enclosure to protect it a bit better from the elements, but that may be counter-productive when going to hot places and the battery heats up even more.

[hbn7hj]

You need a Victron or Bogart shunt based battery monitor. You already know what is good in the way of voltage and current, you just need to see what is happening.

You can then run whatever charger you wish and shut it off when necessary.

I monitor all my charging real time. You can do that with the short lithium charge times.

Solar doesn’t work that way but we are not talking solar here.

[@Michael]

Originally Posted by Urlauber

...would you still try to isolate the converter and add another charger?

As long as you can switch the converter off when you don't want a charge, it can be used.

Originally Posted by Urlauber

Been looking at batteries that come with some monitoring app to easily see the SOC and cell voltage on the existing BMPro screen.

The BMS's that have built-in Bluetooth & monitoring should give you adequate/accurate information on the state of charge of the battery. An external shunt would be nice, but not necessary. If you can monitor individual cell voltages, you'll know whether they're in balance or not.

Originally Posted by Urlauber

Also, I was hoping to install such a battery in one of the two then available battery brackets underneath the car... Is that a terrible idea?

Odds are that the battery is not designed for that. You'd have to think about hot pavement, freezing weather, dirt/rocks/road debris, spray/splash, etc. Some people do it though.

[booster]

Do the Bluetooth apps indicate when the battery is auto top balancing, it the auto balancing is in the BMS?

[Urlauber]

Originally Posted by @Michael

As long as you can switch the converter off when you don't want a charge, it can be used.



The BMS's that have built-in Bluetooth & monitoring should give you adequate/accurate information on the state of charge of the battery. An external shunt would be nice, but not necessary. If you can monitor individual cell voltages, you'll know whether they're in balance or not.



Odds are that the battery is not designed for that. You'd have to think about hot pavement, freezing weather, dirt/rocks/road debris, spray/splash, etc. Some people do it though.

Thank you for your help, all very good points. I am concerned about hot pavement/overheating and spray/splash. Are AGM batteries intrinsically tougher than LFPs? I think some sort of enclosure which insulates the bottom and sides, and covers the top while leaving some openings to ventilate, might be beneficial.

Do you know if there is a way to turn off a converter like this WFCO, or are they pretty much always on if the main switch is engaged? Also, will turning off the converter (charging) disable USB charging outlets and such?
This would only apply when on shore power, which, like I said, happens very rarely. So pulling a plug or flipping a breaker in those circumstances would be doable.

[Urlauber]

Originally Posted by booster

Do the Bluetooth apps indicate when the battery is auto top balancing, it the auto balancing is in the BMS?

The BT app shows the individual cell voltages in mV, indicating in different colors which one is lowest/highest. According to reviews, this changes when charging/discharging, so I assume there is auto balancing in the BMS.

[Urlauber]

Originally Posted by @Michael

As long as you can switch the converter off when you don't want a charge, it can be used.

Reading over the docu, it appears that I could disconnect the converter by pulling the reverse polarity fuses. I hope that interrupts the converter charging of the battery, not the 12V power delivery to the camper. Will test.

This would come in handy if I want to run the genny to use A/C, but don't want to charge the battery at the same time.

[booster]

Originally Posted by Urlauber

Reading over the docu, it appears that I could disconnect the converter by pulling the reverse polarity fuses. I hope that interrupts the converter charging of the battery, not the 12V power delivery to the camper. Will test.

This would come in handy if I want to run the genny to use A/C, but don't want to charge the battery at the same time.

Don't make it difficult. Just put a remote switched relay on the power to the converter. Flip the switch, converter is off.

[hbn7hj]

Just flip the 120 volt circuit breaker to the converter. It is already there. Quit talking about it and get it done.

I still think you should use a shunt based battery monitor. Gives you volts and amps at all times along with state of charge. All the info you need.

[Urlauber]

Originally Posted by booster

Don't make it difficult. Just put a remote switched relay on the power to the converter. Flip the switch, converter is off.

Pulling two fuses is not too difficult... a switch is more convenient, sure, but I wonder how often I will want to do this. This would happen only if 1) I am on shore power (which rarely happens) or run the generator (infrequently as well) and 2) don't want to charge the batteries at the same time. Special case indeed.

It's not like I don't have a backlog of switches I want to install... I did the charge/use switch for the Power Station, and the disconnect switch for the BMPro panel to not kill the tablet battery when the main switch stays on all the time. I know I want to add a switch to disconnect the solar panel, plus I need a switch to interrupt the power to the awning, which tends to slide out cheekily at inopportune times. Maybe a switch to turn the rarely used Winegard off when not needed.

In any case, pulling the two fuses did turn off the converter, while the remainder of the 12V system was still going strong. So I think this is the ticket. Or another switch.

[Urlauber]

Originally Posted by hbn7hj

Just flip the 120 volt circuit breaker to the converter. It is already there. Quit talking about it and get it done.

Relax... breathe... this is all in the designing phase, trying to imagine how things would work if. Soaking up all the knowledge.
So the 30A Main circuit breaker should do it? That would certainly be easier. It does not turn off the converter (I think), but if it interrupts the shore power to it that should work.

Originally Posted by hbn7hj

I still think you should use a shunt based battery monitor. Gives you volts and amps at all times along with state of charge. All the info you need.

I would like to see the voltage of each cell to monitor battery health and leveling, maybe to tell me that I have to do a full charge to bring things into balance. The particular battery's BT app provides that along with SOC and voltage and amps and temperatures and a bunch more. Not sure a shunt based monitor would improve on that, but I know it would set me back another 150 or so and adds yet another thing that can drift or refuse to connect or update or something.

[hbn7hj]

Originally Posted by Urlauber

So the 30A Main circuit breaker should do it? That would certainly be easier. It does not turn off the converter (I think), but if it interrupts the shore power to it that should work.

Nope. It is a 20 amp circuit breaker labeled converter. I use it all the time because I happen to have a second battery charger for FLA. I turn it on the rare times I have shore power. The other FLA charger only works with the generator. Just a quirk of my installation.

Interrupting the shore power to the converter turns it off.

You can get the battery monitors later.

I just ordered a battery without bluetooth because I have bluetooth on a battery monitor in another RV and I notice the current drain, A few miiliamps 24/7 when you only have 100AH to work with mounts up. The battery monitor itself is 150 milliamps.

Bluetooth within sealed batteries cannot be turned off.

[Urlauber]

Originally Posted by hbn7hj

Nope. It is a 20 amp circuit breaker labeled converter. I use it all the time because I happen to have a second battery charger for FLA. I turn it on the rare times I have shore power. The other FLA charger only works with the generator.

Interrupting the shore power to the converter turns it off.

I am not seeing that. Perhaps mine is different, or we're talking about different things?

Originally Posted by hbn7hj

You can get the battery monitors later.

I just ordered a battery without bluetooth because I have bluetooth on a battery monitor in another RV and I notice the current drain, A few miiliamps 24/7 when you only have 100AH to work with mounts up. The battery monitor itself is 150 milliamps.

Bluetooth within sealed batteries cannot be turned off.

That is a good point. Nothing is quite perfect... With my current setup I have a solar panel which tends to fill up the batteries all the time. A bit of drainage wouldn't even be that bad. I am running my internet router off it just to make some use of the solar power.

[hbn7hj]

The converter most likely has it’s own circuit breaker. It would have to be one of the 15 amp breakers. Put a voltmeter on your 12 volt output. It should be around 13.7 volts. Start flipping breakers till it drops.

The last 15 amp breaker is not labeled. Maybe that is it

[booster]

Originally Posted by hbn7hj

I just ordered a battery without bluetooth because I have bluetooth on a battery monitor in another RV and I notice the current drain, A few miiliamps 24/7 when you only have 100AH to work with mounts up. The battery monitor itself is 150 milliamps.

Bluetooth within sealed batteries cannot be turned off.

I haven't been able to find any information about how much continuous drain the Bluetooth in the batteries consumes. I have the same concerns as you about that kind of monitoring and not being able to shut it off if you want to.


Has anybody seen anything on the it? I know having the Bluetooth on runs down the battery faster on phone if it is on.

[Urlauber]

Originally Posted by booster

I haven't been able to find any information about how much continuous drain the Bluetooth in the batteries consumes. I have the same concerns as you about that kind of monitoring and not being able to shut it off if you want to.

Has anybody seen anything on the it? I know having the Bluetooth on runs down the battery faster on phone if it is on.

It used to be a concern, but I think newer BT protocols and implementations are lighter on resources. According to THEM it's about 1.8% over a 26 hour period. Newer phones don't have a way to plug in headsets so you're pretty much stuck with BT.

Also keep in mind a phone battery <> 100Ah LFP. My gutfeel is that it would be negligible, unless they have a really shty implementation.

Now, heating the cells is an entirely different topic.

[Urlauber]

Before I dive into this much further, I want to see what I could get for some slightly used AGM Grp31 batteries that are about 2 years old. If that is next to nothing, I might as well wait and milk them a bit longer.

Been checking out several (no-name) BT equipped 100Ah LFP's. I am sure as competition heats up prices will fall further.

name price ratings comment link
JavaEnegy 350 77 Heating https://www.amazon.com/JavaEnegy-Sma.../dp/B0BSD7PN7W
Chins 380 104 Heating https://www.amazon.com/LiFePO4-Tempe.../dp/B08N56CYS5
Vatrer 390 158 Rudimentary App https://www.amazon.com/dp/B0BQR1RSGG
Temgot 370 7 Touch Display https://www.amazon.com/LiFePO4-Touch.../dp/B0BTBQFLDX
Ogrphy 380 241 Heating https://www.amazon.com/OGRPHY-LiFePO.../dp/B09HB8HMX3

[hbn7hj]

SOK allows the battery to be opened. You could disable the Bluetooth if you wished. I choose not to order it

Did you locate the converter circuit breaker?