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Old 03-30-2020, 09:08 PM   #1
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600 ah AGM vs 480 lithium

I currently have 600 watt solar and 6 6V AGM batteries in a combination of series and parallel for about 600ah of capacity total.

I am thinking about Lithium and moving to 4 lithium expion360viper 120ah in parallel. However that would reduce my amp hours to 480.

I know that AGM has some reduced capacity but is this move worth it in terms of capacity and amp hours?

A little bit about our travels, we have a 2015 30ft bunk and would like to have the capacity of going off grid for up to 6-7 days.
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Old 03-30-2020, 09:35 PM   #2
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Going to lithiums will save a lot of weight, both in your trailer and in your wallet (as the money flies out). A few hundred pounds savings at a cost of $4-$5k. You'll get some more "usable" amp hours. But your current batteries can go below 50% if called upon with a small, but acceptable reduction in life, so the difference may be negligible or not ultimately be as much as you think.

If you like what you have now, stay with it. If you must have the latest & greatest and don't mind the cost, then go with the lithium batteries. Just know the other solar, inverter, and charging components should be replaced with lithium compatible ones unless you've thought ahead on that and already have such components. The costs can really add up fast.
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Old 03-30-2020, 09:36 PM   #3
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For AGM, you don’t want to take them down below 50%, so you really have 300ah of battery. For the lithium, you can take them down to 10% or even fully discharged, so let’s say you have at least 425ah. You are going to get much more usable power with the lithium.

That said, with your solar amount, can/will you use more than what the panels will put back in over a 24 hour period? If not, then why change?
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Old 03-30-2020, 09:45 PM   #4
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I definitely use more than the solar panels provided on our last camping trip! Of course I was in the shade. We did last 4 days without issues though.

We run the inverter usually for my kids sound machine and my other kid likes to occasionally watch a show on the tv.

Yeah I know I need to replace the charge controller to go to lithium but need to investigate what else. I didn't do the install and bought this used so still debating.

I know myself though, eventually I will upgrade to lithium it's just when and I am leaning on not doing that this year and saving some money!
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Old 03-30-2020, 10:38 PM   #5
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Originally Posted by Alreddawg19 View Post
I definitely use more than the solar panels provided on our last camping trip! Of course I was in the shade. We did last 4 days without issues though.

We run the inverter usually for my kids sound machine and my other kid likes to occasionally watch a show on the tv.

Yeah I know I need to replace the charge controller to go to lithium but need to investigate what else. I didn't do the install and bought this used so still debating.

I know myself though, eventually I will upgrade to lithium it's just when and I am leaning on not doing that this year and saving some money!


Your profile says a 2018 model, so you have a 3-stage charge controller. That is sufficient to recharge lithium to a partial state of charge, and the solar panel controller (MPPT or PWM) should have a lithium setting or be programmable. If you can add a solar suitcase, that may help generate enough amp hours for you to last. If not, consider a generator and run it in the morning when the batteries are lower. The combo of a couple hours of generator (I like dual fuel off the propane port instead of gas) and 600w of solar should be able to boondock for weeks. Water will run out before you drain 400+ah of lithium. Remember that lithium also charge faster, so it doesn’t take as much generator/solar time to get from 80% to full.
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Old 03-30-2020, 11:03 PM   #6
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Your profile says a 2018 model, so you have a 3-stage charge controller. That is sufficient to recharge lithium to a partial state of charge, and the solar panel controller (MPPT or PWM) should have a lithium setting or be programmable. If you can add a solar suitcase, that may help generate enough amp hours for you to last. If not, consider a generator and run it in the morning when the batteries are lower. The combo of a couple hours of generator (I like dual fuel off the propane port instead of gas) and 600w of solar should be able to boondock for weeks. Water will run out before you drain 400+ah of lithium. Remember that lithium also charge faster, so it doesn’t take as much generator/solar time to get from 80% to full.
Thanks! I also realized my profile is now out of date. We just traded in our 2018 23ft FC to a 2015 30ft FC bunk with the 600 watt solar and 600 ah AGM.
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Old 03-31-2020, 07:06 AM   #7
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LifePo4 batteries don’t need to be pricey. I just added 8-3.2V, 200 amp hour cells for $1000.00 including BMS.Wired in series/parallel gives me a 12 volt 400AH battery. These are CATL cells. CATL is a major supplier to Tesla, BMW, and Mercedes.

This was a DIH project and I learned a lot from Will Prowse on his Youtjbe channel.
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Old 03-31-2020, 10:03 AM   #8
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Con of lithium:
- up-front cost of batteries is much more than lead acid (of any form).

- requires a BMS (might come with the battery depending on manufacturer / retail package).

- highly recommended is a DC to DC controller for when connected to the tow vehicle (and IIRC to solar as well). Going without is possible, but this risks over-stressing the TV's alternator.

- (maybe) change the power controller to one that is compatible with lithium.

- cold and heat effects the batteries. There is plenty of information available on the effects.





Pro to lithium (not previously noted by others):
- expect lower lifetime costs versus multiple lead battery replacements. At the moment this is a theoretical benefit as I am not seeing where anybody has run their lithium batteries to end of life.

- significantly faster charge rate. Lithium batteries are able to take 100% charge rate (bulk in lead acid terms) until reaching full; then they stop charging completely.

- does not need trickle charging while in storage.
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Old 03-31-2020, 10:37 AM   #9
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I'm curious as to what exactly I may have damaged by my having driven 8k+mi w/o the DCDC controller charging thru the 7pin.
As I understand it the DCDC controller boosts the V to properly charge the BB's, but without a wiring upgrade to the 7pin isn't that moot?

The Burb's 200a alternator is still charging its 1ft away battery just fine, and holding the 20' away BB's at 13.2v pretty well also.

Bob
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Old 03-31-2020, 11:14 AM   #10
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Here is a good reference article on the benefit of a DC to DC converter and risks to the alternator:

https://www.victronenergy.com/blog/2...rging-lithium/
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Old 03-31-2020, 11:35 AM   #11
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If I were buying new batteries, I would buy four Lithiums with 400AH to 480AH over 600AH of AGM. If I already had 600AH of functioning AGM and wanted Lithiums, I would use and abuse the AGMs until they no longer met my needs and then buy the 4xxAH of Lithium. While doing this I would watch for a sale on Lithiums and if the right deal comes along jump at it. Who knows what kind of deals may arise with the current economy? Costco recently had LION 1300's on sale for $699 each. Others reported purchasing Renogy had 100AH Lithiums for around $500 each recently.
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Old 03-31-2020, 12:27 PM   #12
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Quote:
Originally Posted by JayTheCPA View Post
Here is a good reference article on the benefit of a DC to DC converter and risks to the alternator:

https://www.victronenergy.com/blog/2...rging-lithium/
That's all well and good...IF your goal is a complete charge on the lithiums starting at 20% SOC.
Another point, there is no BMS used in the VID.
What about the 20' of inadequate charge line?

I guess the only way to know for sure is to drive until the alternator burns up as in the vid.

Although maybe this explains it...

Maybe the Burb's low tech 200a is up to the task after all.🤔

Bob
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Old 03-31-2020, 02:13 PM   #13
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Your call, I only articulated the risk (and backed-it up) Not sure what the push-back is about though. You want to go a different path of which nobody is disputing and that is fine. Although, this detail does seem like it is a new news item despite that IIRC it got coverage in at lest one of the extensive lithium battery threads. In any event, pay to play is always part of the risk tolerance game.

In analogous manner, people state they drive at posted speed limits where this might actually run faster than the tires' rating. That is their call too


So use a DC to DC converter, or not. Just know what it is there to do.
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Old 03-31-2020, 04:33 PM   #14
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Your call, .
I'm Out

Backed it up?🤔

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Old 03-31-2020, 05:53 PM   #15
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Lithium vs AGM - considerations

Going with lithium batteries has a lot of advantages. Higher usable amp hours and higher constant voltage are two of the biggies. They charge faster because every amp in goes in. Also they charge at a higher constant voltage and higher constant amps. Lead acid lose 15% of incoming charge or more in the chemical energy convertion. Less weight is always nice because you pay fuel to haul every pound. Lithium batteries last a lot longer. Lithiums last significantly longer.

Talking about cycle life is like talking about amp hours. With lead acid batteries, the number of cycles until end of life is determined when the battery will no longer hold more than 50% capacity. Lithium batteries, the number of cycles until end of life is determined when the battery will no longer hold more than 75% capacity. Lithiums have another 25% more to go before meeting the LA standard.

Lead acid batteries (flooded, AGM, Gels) all recommend not discharging below 50%. So a 100Ah LA battery is good for 50Ah. A good quality group 31 AGM (Trojan or Lifeline) will cost $300-$400 per battery delivered. A good AGM will provide 800-1000 cycle life - with end of life = 50% charge capacity.
The discharge voltage of AGMs is directly relative to the state of charge. Typically, 90% SOC=12.65v, 80%=12.55v, 70%=12.42V, 50%=12.15v.(per Lifeline data). Also, AGMs are valve regulated lead acid (VRLA) and should be in a vented area. The do have the potential to vent hydrogen gas.

A lithium battery is good for the rated Ahs. (1) 100Ah lithium = (2) 100Ah AGM. Lithium batteries vary in price but purchase from a company that offers a good warranty - 8yrs or more. They use higher quality BMS and cells. Lithiums will cost $700-$1300 delivered. A good lithium will provide 3000-5000 cycle life - with end of life = 75% charge capacity (lithium standard) or 6000-10000 cycles - end of life = 50% charge capacity (lead acid standard).
The discharge voltage of lithiums is constant. Typically, 90% SOC=13.3v, 80%=13.2v, 70%=13.1v, 60%=13v, 50%=12.9v... at about 10% SOC = 12.5v and then it drops fast.

The charging advantages of lithium are often overlooked. If you have 600 watts - you expect 600w per hour to go into the batteries on a good day. That will work with lithiums but not lead acid based batteries.
It doesn't matter what your charge source is or how powerful it is, the declining Charge Acceptance Rate (CAR) inherent to lead acid and AGM battery chemistries means that you will always have to dedicate more hours of charge time getting the batteries from, for example, 85% to 100%. Also, as the state of charge increases, Smart chargers decrease the charging voltage and amps so not to damage the battery.
Lithium batteries don't have this issue. They'll take all you can supply until they are at 100% and they'll do it much faster.

Lithiums last a long time. Like amp hours, cycle life is a fuzzy area. With lead acid batteries, the number of cycles until end of life is determined when the battery will no longer hold more than 50% capacity. Lithium batteries, the number of cycles until end of life is determined when the battery will no longer hold more than 75% capacity. Lithiums have another 25% more to go before meeting the LA standard. So you can half the LA battry cycle life or double the Lithium cycle life.

Lastly, depending on where you plan to put the batteries, you may consider a larger lithium. Some manufacturers offer lithium batteries that are 200Ah, 300Ah, 400Ah etc. A 100Ah lithium weighs 30Lbs, A 200Ah lithium battery weighs around 60lbs which is about the same as a Lifeline Group 31.

Fortunately, you have a lot of choices:

Expion360 - 6-year limited warranty
https://www.expion360.com/vpr-powermod-lifepo4-lithium

Battleborn - 10-year limited warranty
https://battlebornbatteries.com

AMPS Lithium - Limited Lifetime Warranty
https://lithiummarinebattery.com

ReLion - 5-year limited warranty
https://relionbattery.com

SmartBattery - Limited Lifetime Warranty
https://www.lithiumion-batteries.com/

Renogy - 5-year limited warranty
https://www.renogy.com
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Old 04-01-2020, 12:40 PM   #16
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I definitely use more than the solar panels provided on our last camping trip! Of course I was in the shade. We did last 4 days without issues though.
\
Any idea of solar production?

What is your goal, no generator use, AC cooling, length of avg trip?
Is it possible your system is not actually producing or you have many phantom drains?

My suggestion would be to baseline your system, changing batteries alone may or may not solve your problem, but it will lighten your pocket book when those funds might be best spent elsewhere.
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Old 04-05-2020, 10:43 AM   #17
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Lithium

I had the full conversion done on my 2015 Interstate lounge and I’m extremely pleased. It was stupidly expensive but only hurt while writing the check.
If you want it and can still feed the family , why not. We only get one shot at this life (except Shirley McClain)..
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Old 04-05-2020, 08:10 PM   #18
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New Charging systems

Bob the answer is you have a reliable good ole Burb charging system. The new TV like my truck may or may not charge on the 7 wire. A BMS in the TV computer decides if you get a charge or NOT!

The DC to DC gets around a computer controlled voltage management system. Also Diesel Rigs do NOT want the truck at idle so no charge goes to the Trailer on the 7 wire. Some charge may go after the TV at speed over time and distance when the TV needs are satisfied and it then allows some charge to the Trailer. In addition a DC-DC 30- 60 amps designed to safely charge lithium is a nice feature especially if you do not have solar on the roof.


Quote:
Originally Posted by ROBERT CROSS View Post
I'm curious as to what exactly I may have damaged by my having driven 8k+mi w/o the DCDC controller charging thru the 7pin.
As I understand it the DCDC controller boosts the V to properly charge the BB's, but without a wiring upgrade to the 7pin isn't that moot?

The Burb's 200a alternator is still charging its 1ft away battery just fine, and holding the 20' away BB's at 13.2v pretty well also.

Bob
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Old 04-05-2020, 09:13 PM   #19
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Thanks all! Given that 3 trips are probably cut this year due to the lockdown, I will most likely wait until next year. We see. I might change my mind if I don't have to pay a arm and leg on taxes....
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Old 04-05-2020, 09:21 PM   #20
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Go with Lion. it will
  • save a lot of weight,
  • go down to 10% capacity vs only 50% in LA
  • over a 6 year period, lower TCO

we use battle born Lion
and Victron parts for control and monitoring
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