Need more battery capacity

[Steveva]

Recently returned from a 70 day outing. We saw some temperatures in the middle 30's so we used the AC heat pump. Had to use shore power everyday due to CPAP. Need to get away from shore power. Our old van had two AGM's and water was our limiting factor at two maybe three days camping if we watched our usage. This van has one AGM at 64 amp hrs, size 24.
The CPAP is rated at 90 watts and I'm thinking 10 hours run time, but usually less at 8 hours. We are also adding a compressor refrigerator. All our lights are leds as installed by Pleasure Way. I really don't want to rewire the house part of the van but if we increase our battery capacity are some of our current wire sizes under sized? If we switch to Lithium Phosphate how do we charge the batteries?
We currently have a Surge Power Industries battery separator which (from their manual) will assist in engine starting and protect the charging system.
We also have a Intelipower 9200 power converter. Which I am assuming will be replaced with something similar to charge the Lithium batteries. We also have a 400 watt inverter which we have never used. We seldom use the microwave. We may use the microwave when traveling and then we start the generator (usually at a rest stop) for a warm lunch. One suggestion is to get a large Lithium bank and charge it at home before we leave and then occasionally as needed use shore power to recharge, don't use the van to recharge, and dump the generator, and get an invertor. I don't see that as a viable solution, I would sell the van and buy newer with all the engineering work done by the manufacturer. Of course then we would have payments.
With the old van our routine was set up camp and then bike or hike and maybe take a drive but we never had an issue with battery capacity. If needed we used the drive as an excuse to charge the batteries. We would like to get back to this routine. I am thinking 200 amp hrs would get us there but do we really need that much or will 150 amp hrs do it. I have started a kw hr per day estimate but am wondering if I should continue as I am thinking others on this forum may have a very good idea of what we need from their own experience. I, at this time do not have the time to install solar but may in the future. We have a 2011 Pleasure Way Excel on the Ford E350 with the V10. Thank-you in advance for any suggestions and help, Steve

[Urlauber]

Disclaimer: Everyone is different. Many have converted their rigs to Lithium, but realize that there are some drawbacks.

With that out of the way, here is what we have and how it works for us:

+2 Grp 31 100AHr AGMs
+190W Solar
+Generator

-12V Compressor Fridge
-Truma Heater (Winter)
-roof fan (Summer)
-the usual: Lights, water pump, propane solenoid, etc

I don't like running the Generator (except to run A/C if needed), and we're mostly going to places where we cannot plug in.

So I added a 1200Whr LiFePO4 "Power Station" (LPS) for about $500. When the camper is not used (often during the week) the solar panel slowly fills up that Power Station.

We usually go camping for 3 nights (long weekends).

What I do: I use the LPS during the night to power the fridge and Truma etc as needed. That eats about 350WHr of the capacity, therefore good for 3 nights.
During the day, I use the 2 AGM house batteries, which are replenished by the Solar Panel. Depending on how much sun we get, it may not only keep the AGMs charged, but also allow to charge the LPS a bit. On the other hand, if we're under trees, the AGMs last for about 3 days before they need to be recharged.

This gets us pretty much independence from having to plug in (or run the genny). The nice thing about the LPS that it has its BMS and I can just charge it via the house AGM batteries as needed.

You are probably familiar with the various drawbacks of Li batteries, and you know that you'll most likely need to upgrade the converter and isolator and do something to not burn up your alternator etc.

The challenge is the CPAP, 90W for 10 hours is significant. 900WHrs plus the fridge maybe another 500 (guestimating, depends...) you'd need more than 200AHr Lithium, I think.

Would you have a way to use solar panels, either on the roof, or plug-ins? Where we camp, there is usually no shade, so it's a great option to keep things topped off. I could add more solar, but honestly the 190W panel does most of the work to keep the fridge cool and everything running during the day.

Just some random thoughts..

[Bud]

Originally Posted by Steveva

Recently returned from a 70 day outing. We saw some temperatures in the middle 30's so we used the AC heat pump. Had to use shore power everyday due to CPAP. Need to get away from shore power. Our old van had two AGM's and water was our limiting factor at two maybe three days camping if we watched our usage. This van has one AGM at 64 amp hrs, size 24.
The CPAP is rated at 90 watts and I'm thinking 10 hours run time, but usually less at 8 hours. We are also adding a compressor refrigerator. All our lights are leds as installed by Pleasure Way. I really don't want to rewire the house part of the van but if we increase our battery capacity are some of our current wire sizes under sized? If we switch to Lithium Phosphate how do we charge the batteries?
We currently have a Surge Power Industries battery separator which (from their manual) will assist in engine starting and protect the charging system.
We also have a Intelipower 9200 power converter. Which I am assuming will be replaced with something similar to charge the Lithium batteries. We also have a 400 watt inverter which we have never used. We seldom use the microwave. We may use the microwave when traveling and then we start the generator (usually at a rest stop) for a warm lunch. One suggestion is to get a large Lithium bank and charge it at home before we leave and then occasionally as needed use shore power to recharge, don't use the van to recharge, and dump the generator, and get an invertor. I don't see that as a viable solution, I would sell the van and buy newer with all the engineering work done by the manufacturer. Of course then we would have payments.
With the old van our routine was set up camp and then bike or hike and maybe take a drive but we never had an issue with battery capacity. If needed we used the drive as an excuse to charge the batteries. We would like to get back to this routine. I am thinking 200 amp hrs would get us there but do we really need that much or will 150 amp hrs do it. I have started a kw hr per day estimate but am wondering if I should continue as I am thinking others on this forum may have a very good idea of what we need from their own experience. I, at this time do not have the time to install solar but may in the future. We have a 2011 Pleasure Way Excel on the Ford E350 with the V10. Thank-you in advance for any suggestions and help, Steve

If you want inexpensive, simply 2 of 'Amazon's Choice', the end. Oh, there is the installation............

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[RossWilliams]

Wire size is determined by current draw from the attached appliances, the source doesn't matter. Presumably you have fuses that will blow if you overload the wiring. Chargers and inverters both draw current, so changing them out for more powerful versions may have some wiring issues but probably not.

The main advantage of lithium is weight and size is smaller for a similar amount of power. There are a bunch of other theoretical differences which you may or may not notice in use. One is that lithiums have problems with extreme cold. Can't be charged below freezing and, as I recall, they can't be operated at all below -4. But that is the battery temperature, not the air temperature.

AGM's main advantage is that they are much cheaper, at least in terms of initial purchase price.

[MsNomer]

We switched from AGM to Lithium last year and the improvement has been astounding.

The only other change was to swap the isolator for a Renogy 40A B2B.

[phantomjock]

Quick AGM to LiFePO4 comparison:


What does that translate to? Use a 400Ah Battery bank, of each type of battery. With AGM, you'd have 200Ah available @ 50% discharge - to stay in the "Green Zone" of Safe Depth of Discharge (DoD) to get maximum life vs use.
The same bank size in Lithium gets you to a 20% DoD or 320Ah. You'll note the "Green Zone" is for reasonable life expectancy. Costs are coming down on the Lithium and the biggest factor in my case was size and weight.

While I chose a 400AH bank for comparison, here is Renology's 10/22 chart and you'll note the cost, size, and weight of the AGM vs the Lithium pretty clearly.



The costs etc, don't "scale" but you can find reasonable 400Ah comparisons on eBay and other online sites.
2@ 200aH Renology AGM $359 128# each BATTERY BANK WEIGHT; 250#+, 21x9.5x9 inches (rounded up) Life expectancy - 4 to 5 years
1@ 400Ah Ampere Time LiFePO4 $1649, 21x10.6x9 inches (rounded up) Battery Bank Weight = about 80# Life expectancy - anticipate around 8-10 years.

You could use your energy budget to "right size, an AGM bank and also a Lithium bank, and I think you'd be very surprised at the Cost/Benefit comparison.

Here is a radar plot comparing several classes of batteries. Even if "slightly skewed" by the manufacturer, it should provide a relative comparison.

Originally Posted by MsNomer

We switched from AGM to Lithium last year and the improvement has been astounding.

As they say, Your Mileage May Vary.

Best of luck in your decision making process.

Regards, Jim

[phantomjock]

I wanted to do the maths for a 200Ah Battery bank. With AGM you'd have 100Ah available @ 50% discharge - stay in the "Green Zone." A 200Ah in Lithium gets you to a 20% DoD or 160Ah available - still in the Green.

A few details of Amazon availability:

1@ 200aH Renology AGM
$359; 128# ; 21x9.5x9 inches (rounded up)
Life expectancy - 4 to 5 years

1@ 200Ah Ampere Time LiFePO4
$629; 46#
21x10.6x9 inches (rounded up) Life expectancy - anticipate around 8-10 years.

Cheers - Jim

[booster]

Originally Posted by phantomjock

I wanted to do the maths for a 200Ah Battery bank. With AGM you'd have 100Ah available @ 50% discharge - stay in the "Green Zone." A 200Ah in Lithium gets you to a 20% DoD or 160Ah available - still in the Green.

A few details of Amazon availability:

1@ 200aH Renology AGM
$359; 128# ; 21x9.5x9 inches (rounded up)
Life expectancy - 4 to 5 years

1@ 200Ah Ampere Time LiFePO4
$629; 46#
21x10.6x9 inches (rounded up) Life expectancy - anticipate around 8-10 years.

Cheers - Jim

IMO, you shouldn't believe the 50% usable for AGM batteries as the old 50% rule is bogus number manipulations. There is lots of information on this forum about why the rule is bogus and solid information and just how much total life (in AH available to use) by going to 80% discharge instead of 50%. It is really only about 10-15% less life not the half the life thing they always tell you when referring to the rule.


So you 200ah AGM will give you 160ah usable in most cases with the exception being if you use large amp draws at the end of the 80% discharge as you might bounce of the low voltage cutout on an inverter.


Many of the higher end lithium systems set up for 10% headspace when charging and 10% bottom space when discharging, so they also get 80% of capacity. They do it that way to save wear and tear on the batteries, also.

[phantomjock]

Originally Posted by booster

IMO, you shouldn't believe the 50% usable for AGM batteries as the old 50% rule is bogus number manipulations. There is lots of information on this forum about why the rule is bogus and solid information and just how much total life (in AH available to use) by going to 80% discharge instead of 50%. It is really only about 10-15% less life not the half the life thing they always tell you when referring to the rule.

All understood, and I've seen your reference before. I purposely chose the Renogy Charts as they make AGM batteries, and expected they might have some insight into the properties. Yes they'd have skin in that game and hope to sell you another battery. Coincidentally, they also sell Lifepo4 - with Bluetooth for just under $1000 for 200Ah. So, they ought to be interested in getting out the correct details there too.

Some could say; "Market Manipulation." They are just hoping to get you to buy their LiFePO4. But they still have the AGMs to sell.

Just using their (Renogy) numbers to be fair. Perhaps there is some merit to the occasional "deeper discharge" from your experience, I wouldn't expect that to be useful on a frequent basis.

Unless there is a a side-by-side life cycle test of Depth of Discharge - to battery destruction, it can only be conjecture, or personal experience. It would be a fun test to run and maybe a You-tuber like Hobo, or Will, or Jesse (a "real" engineer), could set the story straight melting down an AGM and a Lithium. But what size batteries to test, discharge rate, recharge to full capacity, or partial, any number of interesting characteristics to consider. How long would it take?

Until then, this information from a reputable company, that makes money from both types of batteries, and ought to be considered as a fair representation, and unless there is contrary,test-based evidence, ought to be accepted at face-value.

Now, the cost/benefit, size and weight, and expected life cycles need to also factor in, and in appear to tilt for many people towards the Lithium.

Unless I misunderstood the intent of the comment. It wouldn't be my first time. And if nothing else, we provided some information and entertainment!

Cheers - Jim

[booster]

Originally Posted by phantomjock

All understood, and I've seen your reference before. I purposely chose the Renogy Charts as they make AGM batteries, and expected they might have some insight into the properties. Yes they'd have skin in that game and hope to sell you another battery. Coincidentally, they also sell Lifepo4 - with Bluetooth for just under $1000 for 200Ah. So, they ought to be interested in getting out the correct details there too.


Just using their (Renogy) numbers to be fair. Perhaps there is some merit to the occasional "deeper discharge" from your experience, I wouldn't expect that to be useful on a frequent basis.

Unless there is a a side-by-side life cycle test of Depth of Discharge - to battery destruction, it can only be conjecture, or personal experience. It would be a fun test to run and maybe a You-tuber like Hobo, or Will, or Jesse (a "real" engineer), could set the story straight melting down an AGM and a Lithium. But what size batteries to test, discharge rate, recharge to full capacity, or partial, any number of interesting characteristics to consider. How long would it take?

Until then, this information from a reputable company, that makes money from both types of batteries, and ought to be considered as a fair representation, and unless there is contrary,test-based evidence, ought to be accepted at face-value.

Now, the cost/benefit, size and weight, and expected life cycles need to also factor in, and in appear to tilt for many people towards the Lithium.

Unless I misunderstood the intent of the comment. It wouldn't be my first time. And if nothing else, we provided some information and entertainment!

Cheers - Jim

Most of the data we have seen on the life cycle of both AGM and Lithium come from the manufacturers themselves and/or laboratory testing of lithium batteries in general. Some also comes from the higher end systems builders that deal with the battery manufacturers and the control devices all the time. The 50% rule questioning is taken from Lifeline's own life charts that they use to tout the 50% run by using the data deceptively.



A lot of people put faith in Renogy for great information, but personally I am not one of them. Their charging and controls is not all that great, but has gotten better lately as the state of the art has moved down into the mid tier sellers.



All that said, I totally agree on the cost vs benefit analysis and that is why ignoring the 50% rule is so very important. If you use total lifetime AH out to use the AGMs look much better at 80% than 50%. At 80% discharge you get 160ah usable out of 200ah of batteries and that would 320ah of battery at 50%. You save half the weight and half the cost and only give up 10-15% of lifetime capacity.



Lithium is getting cheaper so it is getting closer to a wash on costs, unless you need to make certain that you don't get them too cold, to often, which can run up the cost and hassle of having them. But, they also have been lowering the expected lifespan in RV at a lot of suppliers. When all this started, lithium was touted as drop into a system as a direct replacement for lead acid with no extra work needed, 100% discharge, 5c charge rates, no temp limits, 10K cycle life. All of those claims have been backed off of by many lithium manufacturers so I am not sure where it will all settle out.


It is probably most likely that some new technology will come out that blows both AGM and lithium out of the water.


Everybody is free to choose what they want just like with AGM or wet cells, and improved support systems like chargers can improve life in all of them, but many/most have chosen to not use state of the art, expensive support stuff to increase battery life and stick with less capable systems and accept the battery life with be less than perfect. I think lithium will settle into the same pattern as prices drop even more than they already have.

[phantomjock]

I agree as well. Just trying to keep the apples in one basket.

After the cost/benefit analysis, another consideration for folks facing the decision, with will be;

What is my life-cycle cost? Will I get 10 years more out of the vehicle? Will I be around then? Will I want to keep it? Will it add value to resale if I need to get out in a year or 2 due to health, don't like RV travel, want to upgrade, etc.?

In some regards the Lithium batteries will be improved with different chemistries, just as solar panel technology has evolved somewhat. The BMS is a great feature, and more suppliers are understanding the internal heating "requirement." I for one am From Fargo, and won't be finding myself in those temperature unless the magnetic poles shift - or CC proves to be real. Having spent a lot of time in the tropics sans aircon, I think we can make these go.

I recall either roadiebowie or mkguitar made a comment that it is a $10K bite in the wallet. {sorry guys if I got your comment wrong} but that would not be far off. Adding in a second alternator to charge is more expense and work - even if one does DIY. A more cost favorable Lithium option could be spec'ed, but each person needs to understand their basic requirements, and evaluate which approach might work best.

The simplest "drop-in" may fit many folks, whether AGM or Lithium. I think it might just depend where they are in the van-experience spectrum.

[Davydd]

I saw this on Facebook in an answer to a new ARV customer.

“My name is Bmo (Brian) I am one of the Power System Designers and electricians.
Yes, the Autogen doesn’t turn on the headlights anymore.

Starting a few months back we have made the switch for all coaches to have 48v systems. We have developed in house a new lithium battery system that is made in house. The new battery pack is 16.3kwh. The bonus of this pack is that it’s smaller and lighter then our previous 10.2kwh 12v battery system.
With this system we also have a new alternator and charge controller that is lighter and provides 6.6kwh of max charge. At high idle it provides 3.6kwh charge.
We also have a new inverter that is 4000watts jumping up in size from our 3000watt 12v version.
On average this system is a few hundred pounds lighter then the previous 12v systems.

As a few other owners have answered, it all depends on how you use the coach on how long you battery with last before autogen kicks in to charge up the battery pack. Air conditioning is the biggest consumer of power in the coach.

I hope I answered some of your questions and of course we have some of the best owners that make our job easier by helping out new owners!!!”

My comment: 16.3 kWh at 48v = an equivalent 1,358 ah for a 12v battery system. Am I right?

[MsNomer]

AGMs work a lot better if you only have light loads.

Switching from 200Ah AGM to 300Ah Lithium in the same space gave us 5x the usable capacity—as in ability to run what we want to run, including the microwave. By the time the AGMs got to 75% SOC, the voltage was so low under load that microwave could not run. We use the microwave extensively. Before switching to Lithium, we stupidly wasted a lot of money switching to Lifeline because their voltage profile was a bit higher.

[Urlauber]

Agreed, if you want to go all (or most) electric, Lithium batteries will provide the power at a much lower weight. Microwave/Convection oven, induction cooktop, heating/cooling will all eat up the amps.

For lower draws, AGM will do fine, and if you add a Li Power Station like I did the AGMs stay mostly charged while the Lithium does most of the daily work. Simple solution.

[Steveva]

Been going back and forth on the battery decision and finally ordered two 50 Ah lithium batteries. The main reason was they fit in the existing space. Almost went with 100 Ah AGM but could not get one to fit without major work. So the system will be: Current 75 Ah house battery will supply power to everything as before except the refrigerator. The lithium's will power the new compressor refrigerator and on occasion the CPAP when not on shore power. The lithium's will be charged by a 110 vac, 10 amp charger when on shore power or when the generator is running. The lithium's, the charger and the refrigerator will be their own system. The 110 vac side will be shared by both systems. Unsure if I should connect the grounds of the two battery "banks" together, the house battery and the lithium batteries.

[dmb496]

Regarding lithium batteries and Depth Of Discharge :

Dig deep into each manufacturer's information. Some don't place DofD info up front.

[booster]

Originally Posted by dmb496

Regarding lithium batteries and Depth Of Discharge :

Dig deep into each manufacturer's information. Some don't place DofD info up front. The screen shot is taken from Renogy's web site, and is info that isn't readily apparent until a potential customer asked about DofD in the FAQ section.

Why buy a 100 ah lithium battery that performs like a 100 ah AGM?

It is cutoff on the top, but that appears to be in and AGM battery question area. It also spouts the 50% rule of AGM which is exceptionally deceptive in claims (data is on this site about that)



IMO, the manufacturer's are either behind the times or not giving the customers the whole story on DOD vs life on many lithium batteries.


There is getting to be more and more information available the benefits of leaving some capacity at the top and bottom of the capacity for LiFePO4 batteries. How much to leave if pretty much up in the air, I think, but 10% on each end comes up a lot. Lithium recommended specs for capacity and charge rates are getting more conservative quickly, but I am sure the sellers don't want that to be common knowledge.


I have read, but not been able to confirm, that some brands of lithium over capacity the battery so they can limit the discharge lower limit and still make rated capacity.

[dmb496]

Originally Posted by booster

It is cutoff on the top, but that appears to be in and AGM battery question area. It also spouts the 50% rule of AGM which is exceptionally deceptive in claims (data is on this site about that)



IMO, the manufacturer's are either behind the times or not giving the customers the whole story on DOD vs life on many lithium batteries.


There is getting to be more and more information available the benefits of leaving some capacity at the top and bottom of the capacity for LiFePO4 batteries. How much to leave if pretty much up in the air, I think, but 10% on each end comes up a lot. Lithium recommended specs for capacity and charge rates are getting more conservative quickly, but I am sure the sellers don't want that to be common knowledge.


I have read, but not been able to confirm, that some brands of lithium over capacity the battery so they can limit the discharge lower limit and still make rated capacity.

You're correct, my bad. Renogy states an 80% DofD for their lithium batteries. I'll amend my other post.

[hbn7hj]

I’m late to this thread but will suggest that a 10 amp charge rate for the lithium battery is not adequate. To get more, installing a 100AH lithium battery with a 60 amp AC powered lithium charger should fix you right up. That, in addition to your standard battery should keep things powered..

You would need to make the lithium battery easily removable for a Vermont winter. This is essentialy what I run and works very well. Get behind and a 20 minute generator run will get you going. I can charge the FLA from the lithium battery but that is not necessary. With a compressor fridge I would probably add another 100AH lithium battery.

I rarely use shore power but then I don’t run a CPAP. Running the compressor fridge is the killer.

[Urlauber]

To add some more numbers...

My Vitrifrigo compressor fridge draws 4.5A when compressing.
Lets say it runs 30% of the time.
So, a fully charged 100Ah battery should run it for 74 hours. Don't want to run down the battery completely, so deduct 10%.

Almost 3 days. Add a solar panel and you should not run out if you can capture some sun.