Ordered a 100 Ah Lithium Battery - Fiberglass RV


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Old 07-03-2018, 11:14 AM   #1
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Name: Huck
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Virginia
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Ordered a 100 Ah Lithium Battery

Now I have to figure out what I am going to do with it.

Option 1: Replace my lead acid batteries with Lithium batteries
Option 2: Leave my current setup as is
  • 100 w solar panel on roof
  • 100 w solar panel hooked up as needed
  • PWM Charge Controller
  • 2 Lead Acid Batteries mounted on tongue
And
  • Install additional solar panels on roof of van
  • Install lithium battery(ies) in van
  • Add MPT controller
  • Add Inverter
  • Plug Shore Power cable from trailer into Van Inverter
Option 3: Yet to be determined
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Old 07-03-2018, 03:09 PM   #2
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keep it simple!
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Old 07-03-2018, 04:02 PM   #3
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It can't be too simple because the objective is to run my 5000 BTU ac off solar.
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Old 07-03-2018, 04:20 PM   #4
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Originally Posted by Huck View Post
It can't be too simple because the objective is to run my 5000 BTU ac off solar.
how many watts is that? I googled a random 5000 btu, and came up with 450 watts, so at 12V and allowing for power conversion inefficiency, thats 40 amps when on. so if its running with a 50% duty cycle for 8 hours a day, thats 4 hours * 40 amps, or 160 amp*hours at 12V... If you're inland or in the south where it stays hot half the night, you'll be running that alot longer per day.

I wouldn't try to mix lithium and lead-acid batteries, pick one and stick with it. lead-acid better figure on no more than 50% of the AH capacity is actually usable in a day. With LiPo, you should in theory be able to use about 80% of the capacity.

IF your solar panels 'follow the sun', figure on about 4-6 hours of rated wattage per day usable output, if they lie flat, figure less. Keeping this system happy will likely require 500W or more of solar capacity... and on cloudy muggy days, good luck.
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Old 07-03-2018, 05:11 PM   #5
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It can't be too simple because the objective is to run my 5000 BTU ac off solar.
WHOAAAA!!! IMPRESSIVE!!

It'll be fine, once he gets a hold of that lithium battery he'll soon ditch all the lead acid batteries

He doesn't have to do it NOW but I am VERY confidant he will EVENTUALLY be able to!! YAY!!!
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Old 07-03-2018, 05:13 PM   #6
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Originally Posted by John in Santa Cruz View Post
how many watts is that? I googled a random 5000 btu, and came up with 450 watts, so at 12V and allowing for power conversion inefficiency, thats 40 amps when on. so if its running with a 50% duty cycle for 8 hours a day, thats 4 hours * 40 amps, or 160 amp*hours at 12V... If you're inland or in the south where it stays hot half the night, you'll be running that alot longer per day.

I wouldn't try to mix lithium and lead-acid batteries, pick one and stick with it. lead-acid better figure on no more than 50% of the AH capacity is actually usable in a day. With LiPo, you should in theory be able to use about 80% of the capacity.

IF your solar panels 'follow the sun', figure on about 4-6 hours of rated wattage per day usable output, if they lie flat, figure less. Keeping this system happy will likely require 500W or more of solar capacity... and on cloudy muggy days, good luck.
I'm thinking minimum 600 w solar panels and a 2nd 100 ah lithium battery. From someone else's experience, I think the AC will draw a little under 40 amps, so 600 w of solar panels should run the ac during the hottest part of the day and the batteries might give me a few more hours if needed.

I'm getting the lithium battery so I can start playing around and try to determine exactly what I need.

This particular battery is made so you can take out your lead acid batteries and swap in the lithium batteries. They only weigh 30 lbs each and are almost exactly the same size as my current batteries.

My current system works fine for running lights, fan, water pump, etc, so I'll probably just leave it as is, and create a new solar system in the van. The long term plan is to run microwave, refrigerator, ac, etc, just not all at the same time.
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Old 07-03-2018, 05:18 PM   #7
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I am pretty sure the charge requirements for optimal life will be different for lithim than for lead acid. So you will want to keep the charging separated. Which seems to suggest using first one, then the other to run your devices. Yeah, not simple.
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Old 07-03-2018, 05:23 PM   #8
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The long term plan is to run microwave, refrigerator, ac, etc, just not all at the same time.

SAME SAME!! You'll soon want to ditch the propane tank too!

Yep, the zombies are going to come you gotta be self efficient without the need of buying fuel!
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Old 07-03-2018, 05:43 PM   #9
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SAME SAME!! You'll soon want to ditch the propane tank too!

Yep, the zombies are going to come you gotta be self efficient without the need of buying fuel!
Propane will be backup and for heat, hot water, and some cooking.
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Old 07-03-2018, 06:02 PM   #10
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Propane will be backup and for heat, hot water, and some cooking.
Ohhh you have a hotwater tank then yeah I guess you'll have to get eaten when you're filling that tank up

Have you tried induction?
You'll love it! It'll boil water in seconds! If it's a pot full minutes

It won't heat up the inside as propane will so your AC can run longer.
You may not be able to use high but low and medium still will cook faster than propane.
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Old 07-04-2018, 10:23 AM   #11
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I've often read that you'll need a different charge controller for lithium batteries. I've not looked into it carefully.

Walt
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Old 07-04-2018, 12:46 PM   #12
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Programmable if it doesn't have a Lithium setting.
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Old 07-04-2018, 12:55 PM   #13
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I've often read that you'll need a different charge controller for lithium batteries. I've not looked into it carefully.

Walt
the lithium charge controller is built into these sorts of batteries as they are intended for use in a 'lead-acid' environment.
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Old 07-04-2018, 01:53 PM   #14
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It can't be too simple because the objective is to run my 5000 BTU ac off solar.
Where is your A/C located? Ours in under the side dinette seat and doesn't work very well.
But, we operate it on a 30 AMP supply. If yours draws 40 amps, you would be tripping the breakers.
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Old 07-04-2018, 01:56 PM   #15
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Where is your A/C located? Ours in under the side dinette seat and doesn't work very well.
But, we operate it on a 30 AMP supply. If yours draws 40 amps, you would be tripping the breakers.
30A AC is 3600 watts. 40A DC is 480 watts.
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Old 07-04-2018, 02:17 PM   #16
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Where is your A/C located? Ours in under the side dinette seat and doesn't work very well.
But, we operate it on a 30 AMP supply. If yours draws 40 amps, you would be tripping the breakers.
The one originally installed in ParkLiner. The 40 amps is the hit on the 12v system. A 5000 BTU AC is roughly 500 watts, so at 12v dc, that works out to about 40 amps. The guy (Jim in Denver) that tested said it came out to about 37 amps with the AC he used.
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Old 07-04-2018, 05:08 PM   #17
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That inside AC is one of the reasons I didn't keep my Parkliner very long.

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Old 07-04-2018, 05:30 PM   #18
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That inside AC is one of the reasons I didn't keep my Parkliner very long.

Walt
It should be fixable. The problem is air flow. 5000 BTU's should be plenty to cool the space.
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Old 07-04-2018, 07:35 PM   #19
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Yes, but with both the AC and the battery inboard there was almost no floor level storage.
Didn't work for me.

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Old 07-04-2018, 10:23 PM   #20
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Originally Posted by Huck View Post
Now I have to figure out what I am going to do with it.

Option 1: Replace my lead acid batteries with Lithium batteries
Option 2: Leave my current setup as is
  • 100 w solar panel on roof
  • 100 w solar panel hooked up as needed
  • PWM Charge Controller
  • 2 Lead Acid Batteries mounted on tongue
And
  • Install additional solar panels on roof of van
  • Install lithium battery(ies) in van
  • Add MPT controller
  • Add Inverter
  • Plug Shore Power cable from trailer into Van Inverter
Option 3: Yet to be determined

I go with option 3. I assume (almost certainly correct) that these are lithium iron phosphate batteries. These have a nominal cell voltage of 3.2, making them the most suitable "drop in" lithiums. However, all lithium batteries must be kept inside the RV or other air conditioned space for long life! Lithium batteries hate heat. This gets worse the higher the state of charge.

Keep the lead acid batts outside as is. Add these new lithiums inside and run the high draw stuff off of them. You can combine solar charge controllers on one set of panels, but you can't combine sets of differing batteries on one charge controller.

Since you are buying lithiums I assume cost isn't much of an issue, and that you can get a lithium capable MPPT charge controller. That said, it is likely not needed. You can use a 40 amp negative ground PWM model with up to 800 watts of roof mounted panels. If you have sun tracking keep it at 600 watts.
I have 400 watts on my roof and use one of these; "HQST 40A PWM Negative-Ground Solar Charge Controller". (look that up on amazon.)
It doesn't even get one degree warmer than ambient when pushing 410 watts in high noon Arizona sun. I use Renogy panels which are actually under rated and can produce more than the tag says in optimal conditions.

You will want to consider carefully the inverter you choose. Choose one that is capable of starting your AC obviously, but don't way over size it. Inverters only have a certain efficiency. You would do well to hit anything over 80% in most cases. I highly recommend a pure sine inverter, NOT a modified sine wave. If you use a modified sine with an AC compressor you will likely find that it will overheat the compressor and shut down. Find a pure sine model that has a soft start feature and wire that to the compressor directly. This can be done by choosing a mechanical AC and leaving it all maxed out. Turn the inverter on to start the AC. Therefore you can connect a household thermostat to the power switch of the inverter. Some compressors may not be able to start with the soft ramp up though, YMMV based on each unit.

Some 6300 ish BTU ACs are actually more efficient than their 5,000BTU counterparts in the same chassis. I have a 6,350 BTU unit that takes only 400 watts. Keep the inverter as close to the batteries as possible and run the 120v lines longer instead. Inverters often fail to run loads the sticker says they can due to being fed with cables that are too small.
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