Upgrading House Batteries to Lithium - Page 2

AJMike · 08-09-2020, 01:17 PM

Quote:

Originally Posted by DavidM

The Renogy controller shares its amp rating between the solar panels and the chassis alternator input with solar having preference.

Are you saying that the Renogy charger adjusts its output based on how much solar is being produced? That is, are you saying that if there is 15 amps being generated by solar a Renogy 20 amp charger will drop its output to 5 amps to compensate?

BobC · 08-09-2020, 01:53 PM

The size would depend on how many AH you need to replace and how fast you would like to do so. If your three batteries were to be discharged 50%, that's 150 AH that need to be replaced. In a perfect world, a 20A charger would replace that in 7.5 hours of driving. A 60A charger would take 150/60 = 2.5 hours and the 50A combo Solar/DC-DC charger would take three hours.

Again, this is all theoretical, in the real world, the times will probably be longer. Your inverter's capacity is irrelevant. If you're going to be running something off the inverter while driving, it's the amp load that you'll be running tha'ts relevant. This would need to be added to your AH charging need. A 100 watt, 120V appliance will draw 100/12 = 8.3 A at 12V, etc. If your 120V appliance is rated in amps, you need to multiply the 120V amps by 10 to get the amp draw at 12V.

Other than cost, there's no downside to having a larger than necessary charger. It's not going to overload your batteries and, if you plan on adding more batteries in the future, it's nice to have the capacity to do so.

All in all, if I were in your situation, I'd go either for the 60A version or the 50A Solar/DC-DC combo.

**creativepart** · 08-09-2020, 02:25 PM

Mike, In my experience your Solar Charge Controller is the device that regulates how much solar is being used to charge your batteries.

So, when your batteries are depleted even a little and not being charged and there's plenty of sun on your panels the solar charge controller dumps all available power into your batteries. If you are driving and the alternator is charging the batteries OR if you are plugged into shore/gen power and your on board charger is dumping power into your batteries your solar charge controller dials back the amps going into the batteries from the solar panels.

Basically, like any charge controller - when your batteries are full your charger drops to lower amperage levels. So when you are applying a charge to your batteries from some other source those batteries read high surface charging voltage as a fully charged battery and your solar controller responds to that by reducing the amps into what appear to be fully charged batteries.

AJMike · 08-09-2020, 03:40 PM

Quote:

Originally Posted by BobC

Other than cost, there's no downside to having a larger than necessary charger. It's not going to overload your batteries and, if you plan on adding more batteries in the future, it's nice to have the capacity to do so..

I don’t know enough about any of this to say with certainty but I would assume that a 60 amp charger would really stress the alternator, and it would certainly require some substantially large gauge wires,

AJMike · 08-09-2020, 03:47 PM

Quote:

Originally Posted by creativepart

Mike, In my experience your Solar Charge Controller is the device that regulates how much solar is being used to charge your batteries.

So, when your batteries are depleted even a little and not being charged and there's plenty of sun on your panels the solar charge controller dumps all available power into your batteries. If you are driving and the alternator is charging the batteries OR if you are plugged into shore/gen power and your on board charger is dumping power into your batteries your solar charge controller dials back the amps going into the batteries from the solar panels.

Basically, like any charge controller - when your batteries are full your charger drops to lower amperage levels. So when you are applying a charge to your batteries from some other source those batteries read high surface charging voltage as a fully charged battery and your solar controller responds to that by reducing the amps into what appear to be fully charged batteries.

As I said in my previous post, I don’t know very much about the way all of this stuff works, but I always assumed that the solar input combined with the charger input so that if you had a 20 amp charger and were getting 15 amps of solar, then the input to your battery would be 35 amps.

That is what I assumed, but it does not match what I have seen when using the Renogy charger. The opposite seems to be happening - as the solar increases the charger output decreases. The problem is that I don’t know if that is what is supposed to happen or if it is just my charger malfunctioning.

The basic problem I have in understanding this is that I don’t see how the charger would even know what the solar input is. The solar input does not go through the charger, the charger does not have any way to measure the solar charge to the battery unless there is some interaction between the charger and the BMS. Still, what I have seen is a steady decrease in the charger output as the day progressess and there is more sunlight.

AJMike · 08-09-2020, 07:17 PM

CLARIFICATION:

Just to clarify, when I wrote that I did not see how the charger "even know what the solar input is" I meant the solar power input to the batteries, not the amount of solar input the panels were getting. I don't see how the charger knows how much solar power is being sent to the batteries so I don't know how it would adjust its output to compensate.

jipper · 08-10-2020, 06:01 PM

I changed out my stock batteries for Lithium on my 2019 Navion and after much research, I found that the New 2020 option used a closed battery box, 2 -125 amp batteries with a BIM instead of the start solenoid used in the 2019.
The BIM uses a Xantrex controller to turn on/off the BIM.
In speaking with the battery Mfg., they suggested to go with a ABSO - Kisea B to B charger. This also has a solar panel controller built in.
This was not only to prevent large draw from the alternator, but to prevent harming the alternator when the BMS suddenly shut down the house batteries when fully charged.
I will start a thread about my upgrade when I am able to get another trip with the new system.

Jipper
2019 Navion J

Pianotuna · 08-12-2020, 04:38 PM

Quote:

Originally Posted by TheArthurs

We are just about ready to pull the plug on replacing our house battery bank to LiFePO4. This will include the whole shebang...inverter, EMS and battery monitor.
Question is: Will we need to switch out our coach batteries as well? ie, we have 3 deep cycle LA coach batteries, do these need to be lithium as well?

Thanks

Hi,

I would suggest looking closely at SiO2 batteries. They are less than 1/2 the price of Li, and do not require specialized chargers nor battery management. They can be discharged to zero volts 620 times (not recommend, of course). They do well as both deep cycle and starter batteries.

For the inverter, I'd recommend the Victron or Outback hybrid inverter/chargers.

The SiO2 are about $454 USD for a 100 amp-hour unit. They can be used and charged right down to -40.

Winterbagoal · 08-12-2020, 05:49 PM

If weight is a concern, the SiO2 battery's weight is 59.9lbs for a single 100Ah 12V GR27 sized battery. Available from here...
https://www.azimuthsolar.ca/product/...-sio2-battery/
Their charge profile appears to mimic AGM/LiFePO4, so most chargers will work with them. I use a PD9245 to charge my LiFePO4 pair. Works fine along with the solar charge controller.
These things use a FLA type of electrolyte, I believe. Gassing might be an issue.

If cold weather charging is an issue, Relion makes a low temperature charging battery that uses some of the charge current to heat the battery. They can charge down to 4F / -20C.
https://relionbattery.com/products/lithium/rb100-lt

TheArthurs · 08-12-2020, 06:22 PM

Thanks to all who have weighed in on this topic

We have chosen to go with Battleborn and I have spoken with them on the phone and have a bundle all wrapped up. I can hardly wait!!! We are also including a solar controller unit as will be adding 300w array soon afterward.

cj_calva · 08-12-2020, 09:06 PM

Hi
Do not replace the coach batteries (= starter batteries) with LiFePO4. The current load of a house battery is completely different to a starter battery.
Installing LiFePO4 as starter batteries will shorten their life very fast.

Let's say it this way:
A starter battery has to give a lot of power in a very short time (when you start the engine), while a house battery is designed for giving constantly less power over a longer period. So that's also why starter batteries are "not so good" to be used as house batteries.

Lithium based batteries are much more complex than lead-acid batteries like AGMs or normal "car batteries" etc. Lead-acid batteries are working on a basic physical principle while lithium based batteries needs to be controlled (there is a electronic controller inside the battery) for not having a stand-by-effect, drain, dendrites etc. or even burning (lithium is easily flammable, ok, LiFePO4 are "fire-proof", compairing to lithium cobalt products).

Well, you will not destroy the lithium batteries if you start your rv with the house batteries once or twice when the starter batteries are down, but if you do it regularly you will have to replace your expensive lithium batteries after a year at least.

TheArthurs · 08-12-2020, 10:14 PM

Oh no worries, we are leaving our startup batteries as is. ��

Hicks3456 · 08-13-2020, 07:13 AM

Just replaced my house batteries and looked at all options. I ended up going with good quality 2 year warranted wet batteries. I spent roughly $100 on each battery.

I looked at AGM but the costs was over 2x the amount and only had a warranty for 3 years.

At a $1000 a pop Lithium just is a non-starter. In order for it to be feasible they would need to give you a 20 year warranty. I am pretty sure I will not have the same RV in 20 years anyway.

The math does not work for me.

moabdds · 08-13-2020, 10:23 AM

I installed 3 Battle Born batteries for my coach along with the battery isolation monitor sold by Battle Born. This takes care of the charging problem with the alternator, so you don't have to install an inline switch to turn off charging to the coach batteries while driving. This switch has the potential for problems if you should forget, which is very easy to do. I will admit that installing the BIM was a pain because of access, but I managed to get it done and it seems to work like a charm. Battle Born recommends about 250 watts of solar per battery, and I have 1000 watts (4 x250 watts), so I am over-paneled by 250 watts so the system charges faster with less sun. I installed the Victron 3000 watt inverter, which has a 120 amp charger for the coach batteries and a separate trickle charger line for the starter battery. If you'd like to see my set-up, contact me privately and I can send photos.

moabdds · 08-13-2020, 10:26 AM

I forgot to mention that with a battery isolation monitor, you do not need a DC-DC charger. Battle Born recommends one or the other, but not both.

AJMike · 08-13-2020, 05:06 PM

Quote:

Originally Posted by creativepart

Mike, In my experience your Solar Charge Controller is the device that regulates how much solar is being used to charge your batteries.

So, when your batteries are depleted even a little and not being charged and there's plenty of sun on your panels the solar charge controller dumps all available power into your batteries. If you are driving and the alternator is charging the batteries OR if you are plugged into shore/gen power and your on board charger is dumping power into your batteries your solar charge controller dials back the amps going into the batteries from the solar panels.

Basically, like any charge controller - when your batteries are full your charger drops to lower amperage levels. So when you are applying a charge to your batteries from some other source those batteries read high surface charging voltage as a fully charged battery and your solar controller responds to that by reducing the amps into what appear to be fully charged batteries.

Yes, and that corresponds to what I have seen in terms of how the solar works, but my question was about the DC-DC charger.

What I have expected to see when the batteries were down was a combined charge from the charger and the solar, and I have not seen that. What I have seen is that the charger output seems to decrease as the solar increases and I don't have any idea how the charger would even know what the solar controller is doing with the solar input.

If the battery BIM is telling it what is happening then I don't know why I even need the Victron BMS.

AJMike · 08-13-2020, 05:27 PM

Quote:

Originally Posted by moabdds

I forgot to mention that with a battery isolation monitor, you do not need a DC-DC charger. Battle Born recommends one or the other, but not both.

That is the odd thing about the support at Battle Born. Sometimes they recommend a BIM, sometimes they do not. They explicitly told me to not use one.

AJMike · 08-13-2020, 05:34 PM

Quote:

Originally Posted by Hicks3456

At a $1000 a pop Lithium just is a non-starter. In order for it to be feasible they would need to give you a 20 year warranty. I am pretty sure I will not have the same RV in 20 years anyway.

The math does not work for me.

I think it all depends upon how you plan to use your RV. We bought Lithium because we had a specific problem I needed to address and Lithium seemed to be the only way to do it.

Were we camping with hookups all the time I would have kept our OEM batteries. Were we dry camping a lot, but with plenty of solar input I might have gone with AGMs, but we needed enough power to last for a couple of days with very little solar input and no ability to use a generator. That left us with the need for a lot of power, enough to run ou compressor fridge and other small appliances for 2 days with no real solar or generator charge, and Lithium seemed to be the only solution that worked.

For us it was never about whether it was the best solution from a financial standpoint. It was pretty much the only solution.

**creativepart** · 08-13-2020, 07:01 PM

Quote:

Originally Posted by AJMike

What I have expected to see when the batteries were down was a combined charge from the charger and the solar, and I have not seen that.

The reason is your Charger is charging so your solar isn't needed. The solar charge controller sees the voltage coming from your Dc to Dc Charger.

Turn off the DC to DC charger and the Solar charger will go to work. But as I said previously - once ANY charger starts charging your batteries the Solar Charger sees the voltage and scales WAY back.

AJMike · 08-14-2020, 07:12 AM

Quote:

Originally Posted by creativepart

The reason is your Charger is charging so your solar isn't needed. The solar charge controller sees the voltage coming from your Dc to Dc Charger.

Turn off the DC to DC charger and the Solar charger will go to work. But as I said previously - once ANY charger starts charging your batteries the Solar Charger sees the voltage and scales WAY back.

If I am interpreting what I am seeing correctly that is the opposite of what I am seeing.

When my batteries are down, say at 70 or 80%, and the charger is running when the sun is out, what I seem to see is that the charger output decreases and the solar output is high. That is, the Trends display on my Victron smartphone app shows a lower output than it is rated at and the solar charger display seems to correspond to what I see on that app display. For example:

Early morning. No noticeable sun. Charger running. Victron app shows 20 amps (rated output of charger).

Later morning. Sun out. Charger running. Victron app shows 15 amps. Solar shows 5 amps.

Near noon. Sun bright. Charger running. Victron app shows 12 amps. Solar shows 15 amps. Difference perhaps compressor fridge.

The charger output seems to be decreasing while the solar is high.