Replace house batteries with LiFePo4?

[BillSkeen]

Any Palazzo owners replace their AGMs or Lead-Acid house batteries with LiFePo4 batteries yet?

I am working with StartLight in Yuma, AZ on getting some LifeBlue 200AH batteries. Looking to see if anyone has any other recommendations.

Thanks,

Bill

[venturer]

I've been running on a 400AH lithium battery from Lithionics for about a year and I can't imagine going back to lead-acid. One thing to be aware of is that with the higher voltage of lithium, the BIRD likes to keep the house-chassis solenoid energized, leading to a parasitic draw on the house batteries. You can replace the BIRD system with an adjustable option from Magnum for ~$200.

Originally Posted by BillSkeen

Any Palazzo owners replace their AGMs or Lead-Acid house batteries with LiFePo4 batteries yet?

I am working with StartLight in Yuma, AZ on getting some LifeBlue 200AH batteries. Looking to see if anyone has any other recommendations.

Thanks,

Bill

[nothermark]

Please write up what you had to change to make it all work. From what I know it's more than just a battery swap.

[msturtz]

I'd be interested as well.

[venturer]

Other than some sizing issues, it was basically a battery swap for me. I chose to stick with the original BIRD system, and simply disconnect the house sensor lead (this means the chassis batteries only charge when the engine is running, or I reconnect the wire.) Change the charge parameters on the Magnum inverter and solar charger (if you have one) and that was it.

If you're looking to keep the chassis batteries topped off while parked for a long time, the Magnum SBC can replace the BIRD to support adjustable voltage connect/disconnect ranges that are in range for what the lithium battery puts out.

[parks0412]

I was thinking about buying a Relion 300ah, but they are sold out until May.

[BillSkeen]

Originally Posted by parks0412

I was thinking about buying a Relion 300ah, but they are sold out until May.

I thought about using just one large battery, but decided having individual batteries with lower Ah would allow for easier configuration in the motorhome and less expensive to replace if one failed. Two of the LifeBlue 200Ah batteries are comparably priced.

I hope to place my order by the end of the month.

[parks0412]

Venturer- how well does 400ah work for you? I was thinking about starting with one 300ah. I'm sure it would be much better than what came with the coach, but what do you think? I'm assuming your Palazzo has the residential frig like mine. Do your batteries last all night? If I could run the inverter for 8 to 12 hours before recharging, I'd be happy.

[venturer]

Originally Posted by parks0412

Venturer- how well does 400ah work for you? I was thinking about starting with one 300ah. I'm sure it would be much better than what came with the coach, but what do you think? I'm assuming your Palazzo has the residential frig like mine. Do your batteries last all night? If I could run the inverter for 8 to 12 hours before recharging, I'd be happy.

We see a large variance in battery usage depending on temperature, how much we're opening the fridge, etc, so I am a bit hesitant to put out specific numbers. In general, however, we use about 100-200AH for each 24 hour period. With 400AH, we usually go 2-3 days of "normal" usage without any charging. That includes the fridge, daily coffee, a few minutes of microwave/convection, and lights. (We have quite a bit of solar, so "no charging" is unusual for us unless it is really cloudy or we are parked under a tree.)

If you're only worried about getting through the night, 300AH should be more than adequate.

[msturtz]

They only recommend discharging to 50% SOC if I'm reading their specifications correctly. That means for sizing we would need to use the same formula as for lead acid. I can get 2000 to 3000 cycles out of my AGM batteries as long as I only use 20% of the capacity I.e. 80% SOC.

[BatteryPro]

Originally Posted by msturtz

They only recommend discharging to 50% SOC if I'm reading their specifications correctly. That means for sizing we would need to use the same formula as for lead acid.....

Who recommends only 50% DoD? What “formula” are you referring to?

There is a troublesome myth floating around the RV world, one that we hear the most in our showroom and one that I wish did not exist, that you can or should only discharge a deep cycle battery to 50%. This is wrong. All deep cycle batteries can be discharged 100% each cycle without harming the battery. A battery cycle is calculated as a complete discharge and recharge.

There are several factors that affect how many cycles a battery can provide. Some manufacturers, like Trojan Battery, show a linear relationship for cycle life based on how deep the discharge is. Others, like Lifeline, claim a curve that with shallower discharges, greater cycle life can be achieved. So, you may increase life by using a shallower discharge but that should not suggest that 50% is all you can use. Temperature, age, charge rate, voltage, charge frequency and more play a role in battery cycle life.

LiFeBlue battery (www.lifebluebattery.com) has a cycle life calculator built into the battery BMS system. They have taken into account a number of factors and use 80% of capacity removed to calculate 1 cycle. However, like all deep cycle batteries, you an discharge 100% if you need to.

Perhaps you misunderstood the sizing recommendation as being a rule. By sizing your Li-ion battery bank for 50% average discharge, the full time RV’er will find a balance of long life and not struggling with battery capacity between charge periods. This is no rule, only a suggestion to help in sizing. You can have a much larger bank so you have reserve capacity or a much smaller bank if you precisely know your use each day or don’t mind charging more often than once per day.

Larry

[msturtz]

Originally Posted by BatteryPro

Who recommends only 50% DoD? What “formula” are you referring to?

There is a troublesome myth floating around the RV world, one that we hear the most in our showroom and one that I wish did not exist, that you can or should only discharge a deep cycle battery to 50%. This is wrong. All deep cycle batteries can be discharged 100% each cycle without harming the battery. A battery cycle is calculated as a complete discharge and recharge.

There are several factors that affect how many cycles a battery can provide. Some manufacturers, like Trojan Battery, show a linear relationship for cycle life based on how deep the discharge is. Others, like Lifeline, claim a curve that with shallower discharges, greater cycle life can be achieved. So, you may increase life by using a shallower discharge but that should not suggest that 50% is all you can use. Temperature, age, charge rate, voltage, charge frequency and more play a role in battery cycle life.

LiFeBlue battery (www.lifebluebattery.com) has a cycle life calculator built into the battery BMS system. They have taken into account a number of factors and use 80% of capacity removed to calculate 1 cycle. However, like all deep cycle batteries, you an discharge 100% if you need to.

Perhaps you misunderstood the sizing recommendation as being a rule. By sizing your Li-ion battery bank for 50% average discharge, the full time RV’er will find a balance of long life and not struggling with battery capacity between charge periods. This is no rule, only a suggestion to help in sizing. You can have a much larger bank so you have reserve capacity or a much smaller bank if you precisely know your use each day or don’t mind charging more often than once per day.

Larry

I have been working with and reading about batteries for a long time. I work in the research department of a heavy truck manufacturer. Strangely enough battery replacement is a major cost for our research fleet. That said, every major battery manufacturer publishes a chart or graph that describes the number of cycles you should receive for a particular model of battery based on the DOD (Depth of Discharge). Lead Acid batteries are not designed to be discharged to 100% DOD or 0% SOC (State of Charge). For example the batteries in my Palazzo are from Fullriver and the chart reads like this: if I only use the top 10% of the battery capacity or 90% SOC / 10% DOD I can get 5000 cycles out of the battery before it needs to be replaced. However, if I discharge the battery to 100% DOD / 0% SOC I only get about 600 discharge cycles before the battery will need to be replaced. For my rig I selected 80% SOC or 20% DOD as a set point for the AGS (Automatic Generator Start) system. This will give me approximately 2000 discharge cycles before the battery will need to be replaced. If you don't believe me here is the link to the charts Fullriver Battery DC224-6 Product Information Please keep in mind that Lithium based batteries are much more tolerant to deep discharges than lead acid. That said the material on the site suggests to use a 50% DOD measure for sizing their battery packs. That was the point of my question. Lithium battery systems usually use a battery management system to only allow you to discharge the battery to a preset point. However, that specific point may not be the best point for DOD for a long life of the battery. If I'm going to pay $1000 for a 100AH battery I don't want to destroy the battery or reduce it's life by not using it per the manufacturer's specifications.

[nothermark]

FWIW while one may or may not be able to discharge to various levels the cost/benefit ratio sets the optimum for most of us. That is based on the chemistry as much as the design. It's nice to have reserve but we get a long longer life out of lead acid staying above 50%. As I recall Nissan set up their hybrid to run between something like 40-90% for optimum life on NMh. The point is to learn what the chemistry likes and work with it.

[BatteryPro]

Originally Posted by msturtz

.... Lead Acid batteries are not designed to be discharged to 100% DOD or 0% SOC (State of Charge)...... .

You are confusing two different issues: cycle life and the ability to use 100% of a battery. My post was not to discuss the effect shallow verses deep discharge, although I did cover it somewhat, it was to expose the myth that you can not use more than 50% of a battery. People believe that 50% is a magic number that can not be exceeded or something bad will happen.

You provided a link to Fullriver data for the DC224-6. If you will examine the data, you will see that ALL of it, minutes and hours, is BASED on 100% discharge. If the battery can not be fully discharged, they would tell you and base their calculations of how much you can discharge.

The cycle life vs DoD chart you refer to is useless for RV’ers. The chart is based on a 2 hour cycle, something that no RV will ever experience. That’s 112 Amp load continuously per parallel battery. If you have a typical RV 4 battery bank of the 224 batteries, you would have to apply a load of 220 Amps continuously for 2 hours in order for that chart to mean anything. Because an RV battery bank is discharged much slower, a true graph would be fairly linear.

FACT: All deep cycle batteries can be discharged 100%. Think about this: The way a battery manufacturer rates a deep cycle battery is by how much energy it stores IF you discharge it at a specific rate until it is 100% discharged! So, your statement above is wrong. Please stop spreading this myth.

One more thing. It is more likely that you will experience age related death to your battery LONG before the 5000 cycles you mentioned. We design battery bank sizes based on about 30% average DoD. This is a good number for getting the most from a battery bank, having some reserve capacity and keeping the cost to a minimum. With proper charging, our customers get 7-8 years of life.

Originally Posted by msturtz

….For my rig I selected 80% SOC or 20% DOD as a set point for the AGS (Automatic Generator Start) system. ...

I guess I need to address this also: Starting your generator when your battery is at 80% charge is a huge waste of fuel. The battery voltage will rise quickly causing the charger to enter absorb (CV). Your current will be very low for 3-5 hours as you try to reach saturation (100%). You are far better to stop a generator at about 80% full unless that is your only charge source AND you are not going to use shore power for 30 days or longer AND you are only doing this about once every 20-30 days.