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Lithium-Ion Batteries


kfrimr

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I am looking to put some new batteries in our 5th. I am thinking about something over 600Ah. Have you had experance with the new Lithium Ion? Have you found them worth the extra $? Who is coming us as a good source for purchasing them? Any wisdom you can share would be a huge help.

Kent

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Not 16v. You charge them around 14v, and they discharge at around 12.8v.

 

They don't like either being overcharged or allowed to completely discharge.

 

But the do have some huge advantages. Weight is just one of them.

 

Geo

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The chemistry you are looking for is LiFePO4, or Lithium Iron Phosphate. Lithium Ion batteries are way too unstable for mobile use.

 

I was hoping the technology would catch up before I was ready to buy batteries again as swapping to LiFePO4 is my plan. There are very expensive off the shelf batteries with built in cell balancing combined with low/high voltage shutdown. I consider this to be mandatory unless you want a part time job doing maintenance and guarding the batteries for their own safety.

 

Have a look here: http://www.balqon.com/store-2/#!/12-Volt-Systems/c/12286436/offset=0&sort=priceAsc

 

You can drop to 1/3-1/2 your Ah capacity since you will be able to cycle these down to 10% SOC before charging. I have been waiting for a solar charge controller and inverter/charger manufacturer to get on board and build some safe features and balancing circuits so we can have a trouble free system. We could then essentially "Build" our own battery from 4 cells and swap out a bad one if ever needed.

 

I turned a friend on to these earlier this year for use on his mountain top wireless internet sites, but it's still too early to know how it will tun out.

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I gave a presentation on this subject at the rally a couple of weeks ago. Here's a link to my slides: http://rvnerds.com/presentations-from-2015-hdt-rally/

 

Charging voltages and currents vary depending on the presence or absence of a cell-level monitoring system, the particular cell type (even among LiFePO4 cells, there are a number of minor differences in electrode chemistries--from one brand to the next the specifications may be different), and the cell temperature, among other things. I mention it in the presentation, but be careful not to compare amp-hours across different types of batteries--look at usable energy, in kWh. The various cell voltages and cell configurations can make comparisons confusing in a hurry.

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Very, very useful. Thanks!!

 

Has anyone thought of jacking the solar panel array up a few inches to achieve a true tropical roof. I can't see it being a tough change, all you are trying to achieve is maximum air flow under the panels to cool their back while getting maximum change delivery in the panels themselves.

 

Geo

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I gave a presentation on this subject at the rally a couple of weeks ago. Here's a link to my slides: http://rvnerds.com/presentations-from-2015-hdt-rally/

 

Charging voltages and currents vary depending on the presence or absence of a cell-level monitoring system, the particular cell type (even among LiFePO4 cells, there are a number of minor differences in electrode chemistries--from one brand to the next the specifications may be different), and the cell temperature, among other things. I mention it in the presentation, but be careful not to compare amp-hours across different types of batteries--look at usable energy, in kWh. The various cell voltages and cell configurations can make comparisons confusing in a hurry.

Good info there!

 

It would be cool to see Magnum or Outback make a BMS that just plugged into the network. Then the charger built into the inverter could be used?

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Very, very useful. Thanks!!

 

Has anyone thought of jacking the solar panel array up a few inches to achieve a true tropical roof. I can't see it being a tough change, all you are trying to achieve is maximum air flow under the panels to cool their back while getting maximum change delivery in the panels themselves.

 

Geo

 

The thermal environment for solar panels is key to longevity--thermal cycling of solder joints between cells gradually increases resistance and decreases output. A PV panel's output also decreases quite a bit with temperature, so the cooler the panel, the more you get out of it. My intention is to do what you describe, in conjunction with eliminating a lot of stuff on the roof. I might even consider cooling the backsides of the panels if I can make it work without too much headache--and use that heat to help out with hot water.

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Very interesting. I really like the thought of integrated solar hot water. I understand that works fine down to quite low temps. I've been lurking on some of the Aussie forums. In some respects they are ahead of us and the climate in the bush can be savage. A tropical roof is routine because it brings so many benefits.

 

Lots of Lithium Iron in use already, AirCon usage off the batteries, and CanBus managed electrical systems. Also some nice air suspension.

 

I'm starting to think about a project modifying an earlier 30' Roughneck travel trailer. Earlier because it has the bedroom front window which the newer ones don't. Here is a very nice example http://www.kijiji.ca/v-travel-trailer-camper/grande-prairie/roughneck-trailer-duramax-combo-or-separate/1111376234?enableSearchNavigationFlag=true

 

Upgrade the electrics to Lithium Iron with a Hybrid inverter, probably 24v as there is now a lot of stuff like LED lighting that doesn't care if its running on 12 or 24. Big solar array as panels are so inexpensive now. Truma hot water (and your solar hot water would make a great pre-heater even on cool days). A better heating system compared to regular RV furnaces TBD. Possibly MoreRyde suspension and 17.5s for longevity. Possibly move away from roof A/C and de-clutter the roof generally.

 

Geo

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This where I got mine. http://evtv.me/author/mjrickard/. Also check out for good background. http://www.pbase.com/mainecruising/lifepo4_on_boats.. For by far the most in depth discussion you can work your way through this discussion board. It takes a very long time but you know your stuff when you are done. I have read the whole thing twice. http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069.html.

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This where I got mine. http://evtv.me/author/mjrickard/. Also check out for good background. http://www.pbase.com/mainecruising/lifepo4_on_boats.. For by far the most in depth discussion you can work your way through this discussion board. It takes a very long time but you know your stuff when you are done. I have read the whole thing twice. http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069.html.

Thanks for sharing......that should keep me busy a while longer.

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Thanks for sharing......that should keep me busy a while longer.

 

 

Definitely a lot of good info there--but IMO, LiFePO4 cells are still really pricey. I'm behind on a few other things right now, but so far I'm impressed with the Volt battery system. Configuring for 12V will take little more work than 48V, but it's a really modular design all things considered. I'll try to post some pictures tonight.

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Did you a

Ready purchase a Volt battery and start disassembly?

 

Sure did! Here are a couple of pictures:

 

First, here's the whole 435lb battery loaded in the car. Loaded with a forklift and on my way pretty quickly.

 

20151023_171718.jpg

I felt like a certain purveyor of hitches driving back to the RV park--good thing the rear shocks are new:

20151024_130643.jpg

Here's the batttery with the composite cover removed:

20151024_153157.jpg

And here with the first (and at ~200lbs, heaviest) module removed:

20151024_160546.jpg

Getting this thing up the stairs into the RV was no picnic working solo.

20151024_160538.jpg

 

I should get a chance to post more tomorrow.

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