Thor Tiburon - Replace Gen w/LiFePo Batteries

[rmackay]

I am considering replacing all the batteries (engine and house) in the Tiburon with LiFePo batteries.

In addition, I am considering taking out the diesel generator and in the space it occupies, installing two 400 Ah LiFePo batteries and a 200a dedicated alternator for charging these (should take 3-5 hrs of engine run/drive time to fully charge). Result would be 200+ lbs of gained OCCC weight capacity and 800 Ah / 10k Wh of battery capacity. This should give me roughly 48+ hrs of run time with fridge, A/C, and typical other current usage. Does that make sense to do? Am I calculating things correctly? Other benefits are no smoke/smell of diesel, no maintenance of diesel generator, green, etc.

My main goal is to be able to carry more stuff/people in my Thor Tiburon, but to do that, I need that additional 200 lbs of OCCC capacity that the lighter batteries yield.

Thoughts?

Thank you in advance.

[Lt Keefer]

Sounds like a DC to DC charger should be on your list. Check out the Foresty Forrest channel on youtube. He has a sweet setup for his van.

[The Gritz Carlton]

If selling it, how much do you want for the generator?

[rmackay]

We are, hence the dedicated 200a Alternator just for these batteries. Or am I not understanding your suggestion?

[rmackay]

I'm told that a fair price for that specific unused generator is $4500-$5000.

[DavidEM]

If I were doing your project, I would buy a high output, externally regulated alternator such as Balmar sells along with their external Lithium capable regulator with the external temperature probe for the alternator.

The regulator would then give you a lithium specific charging profile and the temperature probe would protect your alternator by cutting back DC output when the case temp gets too hot. Both features are what a DC to DC charger does but more crudely as it justs has one or maybe two charging amp settings. The Balmar regulator actually manages the alternator case temp.

It sounds like an expensive and ambitious project just to pick up a few OCC pounds. Couldn't you do that with suspension mods?

David

[Chance]

Originally Posted by rmackay

......cut..... Result would be 200+ lbs of gained OCCC weight capacity and 800 Ah / 10k Wh of battery capacity. This should give me roughly 48+ hrs of run time with fridge, A/C, and typical other current usage. Does that make sense to do? Am I calculating things correctly?

.....cut.....

Thoughts?

Thank you in advance.

For clarity, an air conditioner won’t run for 48 hours on 800 Amp-hours of 12.8 VDC batteries. When running steady on a hot day, I’d expect 6~8 hours at best before you would need to recharge. If taking 4 hours of fast idling with 200-Amp alternator, you would end up running diesel van engine too much of the time.

I personally support the conceptual design of what you are considering, but it has to be accomplished in a much more efficient manner from the start to make it viable if sustain air conditioning is planned.

If I were you, I would not eliminate the diesel generator in order to save a little weight unless air conditioning will be limited to short periods or overnight only. Just my 2 cents.

[Chance]

P.S. — The Fit RV guys did such a modification to a gas ProMaster-based Winnebago Travato if I recall correctly. You may want to research their project to gain insight. It’s not exactly the same, but fairly close.

[rmackay]

If the A/C consumes 15 amps then 800 Ah of capacity / 15 amps = 53 hours of run time. I understand that it does not include the fridge and lights and what not, but way more than just 6-8 hours. If not, where is my math wrong?

[sandy1970c]

Hi, I love the idea of the project, and have been interested in it ever since seeing the Volta system. However, for some reason, they say you only get 1 hour of run time for a 15K AC when using 200 Ah batteries. Here is the link:
AM Solar

"If your goal is to run an air conditioner in your Trailer or RV with your lithium batteries, know that one fully charged 200Ah lithium battery will give you about one hour of run time on a typical 15,000 BTU air conditioner, assuming no other loads."

From Battle Born:
"For example, a 100 Ah lithium battery will power a typical 15,000 BTU RV AC unit for about 30 minutes. If you’re RVing in hot weather, running your AC for 30 minutes likely won’t do much to increase your comfort. However, if you had a bank of eight 100 Ah batteries, it would run for about four hours. This may be just enough time to beat the heat in the hottest part of the day."

[reminckv]

Originally Posted by rmackay

If the A/C consumes 15 amps then 800 Ah of capacity / 15 amps = 53 hours of run time. I understand that it does not include the fridge and lights and what not, but way more than just 6-8 hours. If not, where is my math wrong?

15 amps at 120v AC is 150 amps at 12v DC. Your math is off by a factor of 10, not to mention the loss of the inverter.

[dkoldman]

Originally Posted by Chance

If I were you, I would not eliminate the diesel generator in order to save a little weight unless air conditioning will be limited to short periods or overnight only. Just my 2 cents.

Wow, this thread has made me love my generator more. I really struggle to understand the fascination with removing a generator from a RV that was designed to run off a Genset?

I do get those that complain about noise, especially propane; and I don't like diesel smell either. But I will never buy a diesel anything, but if I did;' the smell should not be an impediment.

My lithium day may come, and if it does, it will be when the Mfg companies can mass produce and all of the details are worked out.

Best advice I got from this site when shopping for RV. I wanted 2 ACs badly because I live in hot Texas, but most all the RVs I saw of models I wanted only had 1 AC, so I was planning a mod in some cases a new RV to add a 2nd AC. Then someone said, if you want 2 ACs in RV, buy one with 2. It was simple but I am glad I patiently waited. If I had 1 AC, I would be miserable and not use the RV as much.

[16ACE27]

Originally Posted by reminckv

15 amps at 120v AC is 150 amps at 12v DC. Your math is off by a factor of 10, not to mention the loss of the inverter.

Truth! Looks like 5.3 hours or less.

[Chance]

Many air conditioners used in vans (particularly the smaller high-efficiency units used with lithium-battery powered systems) do not require 15 Amps. In normal use I would expect closer to an average of 10 Amps; unless parked in desert.

A few vans that have 12 VDC air conditioners can often only pull between 60~100 Amps depending on conditions.

Much depends on weather, but 8 hours on 800 Ah should be possible. At night, the A/C should run longer than 1 hour per 100 Ah at 12.8 VDC.