LiFePO4 Deep Cycle Batts (again)

[DonTom]

We have 600 amp hours of LifeBlue lithium coming (3 batteries). New charge controller for solar has arrived plus some other miscellaneous stuff. Kevin is getting anxious! He loves messing with the motorhome.

And I thought my 300 AH of lith was a lot!

I see you have $5,685 worth of batteries coming in. And I thought I spent a lot on a battery! I assume you are a full-timer and boondock a lot.

I also mess around with my Class C a lot. I am always finding something to change or improve ( or fix!).

I don't like working on houses, but RVs are different.

-Don- Auburn, CA

 

[UTTransplant]

Ours weren’t quite that high, but they are expensive. We do dry camp a lot, 12 weeks or more total a year, and sometimes more, but we aren’t full-time. We are gone 6-8 months a year total though. We have a Class A with a residential refrigerator and an entertainment/satellite system that uses an obscene amount of power when it is on (we unplug it when we aren’t using it). I admit it is a bit of an extravagance, but if we average it over 10 years it doesn’t look as painful. Tiffin has a advertising phrase about “Roughing it Smoothly,” and we do like our comforts.

 

[DonTom]

We have a Class A with a residential refrigerator

Does that mean when you're boondocked, you have to run an inverter to keep the refrigerator on?

What is the advantage of having a residential refrigerator in an RV? Is it the size? Is there a reason why they cannot make RV/ propane refrigerators the same size?

What is the power consumption of it?


-Don- Auburn, CA

 

[UTTransplant]

Yes, we have a 2000 watt inverter. after having traditional RV 3 way refrigerators for many years, we appreciate the residential version a lot. It is bigger, always stays the right temperature, and the ice cream is always really frozen. We used to do all the messing around the adjusting the refrigerator temp, moving the trailer until the frig wasn’t on the sunny side, etc. No more; it just runs. We have a standard 3 door Maytag. Oh, and it would be 1/4-2/3 the cost of a good sized RV refrigerator. The way we use it, it need 100-120 amp hours per day. See why we have more batteries?

 

[DonTom]

Yes, we have a 2000 watt inverter. after having traditional RV 3 way refrigerators for many years, we appreciate the residential version a lot. It is bigger, always stays the right temperature, and the ice cream is always really frozen. We used to do all the messing around the adjusting the refrigerator temp, moving the trailer until the frig wasn’t on the sunny side, etc. No more; it just runs. We have a standard 3 door Maytag. Oh, and it would be 1/4-2/3 the cost of a good sized RV refrigerator. The way we use it, it need 100-120 amp hours per day. See why we have more batteries?

Yep. Sounds like a good idea when you have 600 AH worth of lith batteries.

However, I find my cheap, small RV refrigerator is reasonable enough for me. I keep it a bit on the cold side, but yeah, they do vary quite a bit compared to my home refrigerators that have a digital readout and can be set right at +38/-2.

But -2F makes ice cream a bit too hard, IMO. IMO, a separate temp is needed for ice cream, a bit warmer than that -2F. Do any refrigerators have a separate ice cream section?

I just looked it up here and now see the problem. Ice cream should be stored around that -2F but served around +10 F. I guess a wait of several minutes is the answer. I prefer ice cream to be somewhat soft.

-Don- Auburn, CA

 

[AStravelers]

Many higher end gas motorhomes and most new large diesel pushers now come standard with a residential fridge. Some offer an extra cost option for a gas/elect fridge since the residential fridge is less expensive than the gas/elect.

 

[Larry N.]

Many higher end gas motorhomes and most new large diesel pushers now come standard with a residential fridge. Some offer an extra cost option for a gas/elect fridge since the residential fridge is less expensive than the gas/elect.

Yep -- my Ventana came with 8 6V batteries and a 2K inverter, and there isn't even any propane on board. Heat and hot water are via the Oasis (similar to Aqua Hot) and stove top is induction heat. The oven is microwave/convection, and does well for us. Induction burners heat much more quickly than gas or resistive electric and can have water boiling before gas would have it more than barely warm. Of course it does require that the pan/skillet be magnetic, but we have several, and stainless steel is almost non-stick, to boot.

So if we boondocked as much as Pam and Kevin do we'd look seriously at a similar setup, but we're not on the road nearly as much.

But I agree with Pam (as does DW) that the residential fridge is a drastic improvement (for us) over the absorption style, partly because of capacity but as much because of the much improved performance.

But -2F makes ice cream a bit too hard, IMO. IMO, a separate temp is needed for ice cream, a bit warmer than that -2F. Do any refrigerators have a separate ice cream section?

I just looked it up here and now see the problem. Ice cream should be stored around that -2F but served around +10 F. I guess a wait of several minutes is the answer. I prefer ice cream to be somewhat soft.

I like it a little softer, too, so (at home) when I don't want to set the ice cream out for several minutes to let it soften, I put in in my 1200 W microwave for about 11-12 seconds (for a half gallon) and it's about right -- small adjustments for lesser amounts (YMMV).

 

[DonTom]

I put in in my 1200 W microwave

Yeah,

I have done the same many times. For just a few seconds (much smaller amounts than half gallon).

-Don- Auburn, CA

 

[UTTransplant]

I like it a little softer, too, so (at home) when I don't want to set the ice cream out for several minutes to let it soften, I put in in my 1200 W microwave for about 11-12 seconds (for a half gallon) and it's about right -- small adjustments for lesser amounts (YMMV).

I am lactose intolerant, so I can have my ice cream only in small quantities. I use the little pint cartons, and 5 seconds in the microwave makes it nice.

And the batteries have made it to Iowa! Maybe they will arrive in the next day or two. Kevin has already installed the new charge controller and added a new fuse of some type.

 

[shorts]

We have a 2015 fifth wheel that came with a residential fridge and we love it. We fulltime and boondock a lot but have also put in the batteries and solar to do that. We definitely would not go back to a non-residential fridge.
Vicki

 

[DonTom]

I just went out to our RV parked in our back yard and tested the voltage drop for our 5 year old lithium batteries and the voltage drop was only 0.3V for our fully charged batteries.

What is your unloaded voltage? Mine is speced at 12.8V. If we go by this number, then under my large load, mine also only dropped 0.3 volts when it was down at a steady 12.5V.

Perhaps I am not supposed to be concerned about the voltage that is above spec as 12.8 is the spec. and I should not count the voltage above 12.8 as being a part of the voltage drop.

And do you know if your unloaded voltage was higher when it was new?

If I ignore what happens above the unloaded spec voltage, then my drop is the same as yours. About what I would expect for a battery with a capacity of 2,560 watts. 0.3 volts is almost nothing under such a load and that also explains the large drop at first and then the very steady voltage under a heavy load a few minutes later.

-Don- Auburn, CA

 

[AStravelers]

What is your unloaded voltage? Mine is speced at 12.8V. If we go by this number, then under my large load, mine also only dropped 0.3 volts when it was down at a steady 12.5V.

Perhaps I am not supposed to be concerned about the voltage that is above spec as 12.8 is the spec. and I should not count the voltage above 12.8 as being a part of the voltage drop.

And do you know if your unloaded voltage was higher when it was new?

If I ignore what happens above the unloaded spec voltage, then my drop is the same as yours. About what I would expect for a battery with a capacity of 2,560 watts. 0.3 volts is almost nothing under such a load and that also explains the large drop at first and then the very steady voltage under a heavy load a few minutes later.

-Don- Auburn, CA

My battery voltage stays between 13.4V and 13.1V.

Here is a lithium battery voltage to SOC chart:

 

[DonTom]

Can somebody please explain why the spec on my battery is 12.8 VDC when the above chart says that is only a 17% SOC?

How are these batteries rated in voltage? At 17% SOC?

So my 12.8 volt battery was at a 70% charge when I received it at 13.2 VDC.

Thanks for the chart. I will print that out and see how it compares to my SmartShunt in the real world. First I need to see if I can really charge it up to 14.4 V. I take it that I should still wait around 30 minutes after the charge to check the voltage?

-Don- Auburn, CA

 

[Dreamsend]

Hi Don
Likely I'm missing something here, but why all the concern about voltage "drop". If the SOC numbers are good, what are you trying to figure out by doing the voltage drop testing? If you have enough juice charging your batteries . . ? I've had lithiums for nearly 2.5 years now, and your chart is right on. My SOC will read 100% and 13.6 to 13.7 V at times (solar only generating). During those times, the batteries can still be in bulk charge profile. When I plug into the grid or run the generator, I'll get 100% at 14.1 or 14.2 V. At that voltage, the batteries are in float. AM Solar says this is all normal - something to do with the solar but I've not pressed them to explain what. Anyway, just curious.

Linda

 

[AStravelers]

Can somebody please explain why the spec on my battery is 12.8 VDC when the above chart says that is only a 17% SOC?

How are these batteries rated in voltage? At 17% SOC?

So my 12.8 volt battery was at a 70% charge when I received it at 13.2 VDC.

Thanks for the chart. I will print that out and see how it compares to my SmartShunt in the real world. First I need to see if I can really charge it up to 14.4 V. I take it that I should still wait around 30 minutes after the charge to check the voltage?

-Don- Auburn, CA

You will have to ask the company that sold you the battery just what they mean when they spec the battery at 12.8V.

I have seen lithium batteries with that 12.8V spec and it doesn't make a bit of sense to me.

As you can see from the voltage to SOC chart the useable voltage is from around 13.3V at 90% to 13.0 at 30%. (Yes you can take lithium to 10% or 20% full. I don't. I also don't I constantly run vehicle engines at the redline or lug the engine.)

Maybe it is something like 12V batteries are really fully charged at 12.6 to 12.7V.

Or they don't want to worry potential buyers by publishing a spec of 13.4V when they are designed to be used in 12V systems. That would be confusing to people.

Yes, you can charge your batteries up to 14.4 to 14.6V. However you don't want to keep them constantly charged and not used at 100% full. Lithium prefers to be at 90%-94% and stored at 50%-70% full.

Charging at 14.4 charges them quickly and then you want to drop in to basically a float voltage of 13.4-13.6V.

One other thing, is while lithium is 100% full at 13.6 or above it drops very quickly to 13.4V at 99% full.

 

[DonTom]

Anyway, just curious.

Same here, but I am curious about how they spec the battery and why the large drop at first and then a very steady 12.5 VDC that no longer drops at all.

I do NOT consider any of it to be a problem, just a curiosity, as it wasn't what I expected. I expected my 12.8 volt battery to be 12.8 volts when fully charged, for one thing, as that is what they advertise. 14.4 volts isn't all that close to 12.8.

-Don- Auburn, CA

 

[DonTom]

Or they don't want to worry potential buyers by publishing a spec of 13.4V when they are designed to be used in 12V systems. That would be confusing to people.

And they way they are doing the 12.7V spec is confusing you as well as me.

But 13.4V would not confuse us at all.

I will post the question to AmperTime for clarification. I will do it right after I check my battery voltage to see where it is at right now.

I will post here what they say.

-Don- Auburn, CA

 

[DonTom]

Here is the answer. It is rated at what minimum voltage it will hold for 95% of its discharge. IOW, it is rated at 5% SOC when almost totally discharged.

" Ampere Time LiFePO4 battery’s flat discharge curve holds above 12.8V for up to 95%* of its capacity usage, providing astronomical boosts in run-time compared to only 50% in Lead Acid. (* 95% Efficiency)"

 

[DonTom]

The price of my battery went down in price by $200.00 since the day I ordered it.

Bad timing, caused by my compulsion!

-Don- Auburn, CA

 

[DonTom]

Today, I did a little more testing on the new house battery. I was curious what would happen if I fully charged it and then ran the engine and checked my SmartShunt.

The starting of the engine discharges the house battery (very little) instead of charging it. Not too surprising because the resting voltage then fully charged on my new house battery is just a few tenths of a volt below 15V. According to my SmartShunt, when I start the engine the house battery drops 0.3 of a volt and has a 12 watt drain. A drain that is not there when I turn off the engine. In fact, then I get a gain (small charge from my solar) with the engine off.

I expect it to drop a bit more as I drive, if anything, until the house battery voltage is the same as the voltage from the alternator. And that could take a very long drive!

When the house battery voltage gets below the alternator voltage, then it should charge and put a load on the alternator, so what I will try later is to see how well the alternator charges the house battery when it's discharged quite a bit. Discharging this thing could take a while and I probably won't try that until my next time I am boondocked for a few days without using the generator.

-Don- Auburn, CA