12v A/C system - Page 2

mojoman · 07-17-2014, 04:13 PM

Seems the chinese are buying up the battery businesses and technology, A123 systems was bought by the chinese after it was bailed out by our tax dollars. Maybe we will get cheaper cells soon.

Davydd · 07-17-2014, 05:13 PM

Right now I am assuming lithium-ion batteries in my Advanced RV on order. Nothing has been finalized yet as they are still researching. They have however been installing the lithium ion 100ah deep cycle Smart Battery in their RVs. They weigh about 1/3rd an AGM and can power down 80% safely instead of 50%. So 4 lithium ion batteries would be about equivalent to having 6-7 AGM batteries. That could represent a savings of over 300 lbs. in weight.

rsrogers4 · 07-18-2014, 02:11 AM

Quote:

Originally Posted by Davydd

Right now I am assuming lithium-ion batteries in my Advanced RV on order. Nothing has been finalized yet as they are still researching.

Check out the products from MasterVolt, http://www.mastervolt.com/automotive/products/. Almost by definition, boats are disconnected from shore power for long stretches of time. MasterVolt is the most highly regarded marine power management system in marine applications. They have several different battery types available, including lithium ion.

mojoman · 07-18-2014, 05:24 PM

This place will make you a custom battery or you can assemble on yourself.
http://www.lithiumbatterypack.co/Batter ... _c_94.html
I will go through them, if a battery goes bad is usually because one of the cells crap out and you can replace just one cell rather than trashing the whole battery. Its also allot cheaper, almost half the price per AH of the fancy ones for people like me who now have lower income due to Obamacare . I have made many motorcycle batteries that have lasted years from bad Dewalt battery packs, just replace the one bad cell and they are good to go for years.

Davydd · 07-18-2014, 07:46 PM

At Advanced RV Fest they had on display individual cell lithium ion batteries and their Silverleaf controller was monitor voltage and temperature of each individual cell. Whether they will have something new is what I don't know. They have been using the 100ah 12V Smart Batteries.

This is one example of a B they had under construction using 4 lithium ion batteries. My understanding is that without an Onan generator they would move the two batteries on the sides up with the other two batteries and make those battery compartments at the back of the van two more storage bins.

wincrasher · 07-18-2014, 07:57 PM

Wow. $1299 for this battery! I wonder if it's just drop in and you could charge it with the Progressive Dynamics 9000 series charger/converter I have in my van.

http://www.lithiumion-batteries.com/...on-battery.php

On one of thier pages, they have a cost comparison. They claim this battery is good for 5000 cycles, which is over 10 times a lead-acid battery, so therefore you'll save money in the long run. Buy one of these or 10 of the other. I doubt you'd go thru 10 lead-acid batteries in 10 years. I think most lead-acid are good for 3-4 years depending on care.

I do like the weight savings though - this one is 31 pounds compared to ~70lbs for an AGM. - that alone could make it worth it on a B.

Davydd · 07-18-2014, 08:37 PM

Don't forget you can also discharge a lithium ion battery more so four lithium ions is equivalent to about 7 lead-acid batteries in amp hour use. They also recharge faster so that engine idle charging idea makes a little more sense. In "theory" they are maintenance free. I would not be having to check the water levels every time I go on a trip as I do now, so it might make more sense to not have access to the under floor boxes. If you can monitor temperature and voltage of every cell and they can last maybe longer than you will with the B that maybe once in a blue moon you might have to put the B up on a lift to get to them under the floor. That is kind of a tough concept to accept. I think I would still like access to everything.

I'm going for the convenience. I already know that if I don't run the air conditioner I might be putting in a bit of overkill but I am also looking for no-brainer decisions where I go and where I sleep at night and the full electrical use of the van on the AC side of things without needing to run a noisy generator. I doubt I would use that engine idle charging much, if ever, either.

Boxster1971 · 07-22-2014, 06:05 AM

Quote:

Originally Posted by mojoman

Lithium Ion Batteries are quite expensive and are an upgrade for RV batteries. They are a fraction of the weight, last multiple times longer and can be drawn down much lower than a lead acid without damage thus providing more power. They take a different type of charge as they can take more amps faster and at a higher voltage. I used to make my own lipo motorcycle batteries from Dewalt battery packs when I had several motorcycles and got fed up with replacing them almost every year. A 4 cell lipo battery weighs about a 1 lb, size of soup can and can start a car. They are on the market everywhere now. Rather than buying a nice inverter and a new generator, I'm going to spend the extra coin in the batteries and use one of my old portable generators. There are venders who will build your battery pack to your specifications much cheaper than buying one of the pre made ones on the market. Or you can assemble the cells yourself.

What about cold weather operation? Every lithium battery for RV use I've read about have sub-freezing limitations.

- - Mike

mojoman · 07-22-2014, 09:39 PM

When you put a load on them when cold,they warm up. They also hold voltage @ around 13.8v so most everything using a motor runs better. Starters spin faster etc...

Davydd · 07-23-2014, 12:12 AM

Mike,

The limitation is you cannot charge the li-on batteries below freezing. If they are already charged they can still be used. Covered this with a reference in another thread.

Little Tex · 08-07-2014, 09:55 AM

Are the LiPo batteries safer than lithium ion? I would be dubious of anyone offering li-ion batteries that were custom AND cheaper than normal as those are known fire hazards. You'd need a good system to regulate charging and prevent over-charging because an RV is not like a motorcycle. A potential fire hazard is a much bigger problem. So, be careful. But also, please post everything if you try this out. I am very intrigued by the advent of solar & battery powered A/C. I know people have tried, but I don't hear much about actual usage. The options are increasing and the prices are dropping annually, though. I expect this is about to be the next big thing in RVs.

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