DC electric air conditioners are a reality

[Jack Mayer]

10 hours ago, sushidog said:

Here's their unfortunate experience with their LiFePo4s "Considering that our batteries are seemingly not on track to outlive an AGM bank as much as theory promised, our personal value calculation haven’t worked out nearly as well as we had hoped."

Chip

Your numbers seem accurate, although I'll admit I have not worked them through. But you are overlooking a few things.

1) since C&C put in their LFP bank things have changed a lot. Also, they were educating themselves as they did it. "Bleeding edge" activities can hurt.....and that is what they were doing at the time. Also the reason I did not recommend LFP at the TIME.  You are aware of the issues due in part to their efforts. You would not do what they did.

2) The lifetime of the various lithium chemistries is pretty well demonstrated at this point. So I would not worry "too" much about it.

3) You should seriously consider used E-car battery sets. Which can be had in the 2-3K range. Yes, you will have to do some work on them, but you seem capable of that. It is not rocket science. 

4)The biggest issue is still "environmental", but the facts are well known at this point, and can be managed. The BMS will not allow charging if it is not "happy". In the project I'm currently working on we are conditioning the battery/utility compartment. But that will not work for everyone. 

I recommend that anyone putting on solar put on the max that you can fit on the roof.....unless it is a total budget project. Then tradeoffs need consideration. But you can never have "too much" solar harvest.  IMO.

[sushidog]

Thanks, Jack.

I value your opinion. I looked at the Prius battery packs a couple years ago but learned that they are nickel metal hydride not lithium. Which Hybrid battery packs would you recommend I look at? Cracking into one and rewiring for 48 volts wouldn't be a problem as long as it wouldn't affect the BMS. Yes I understand that LiFePo4s are more temp sensitive and the fact that pioneers like C&C end up with more arrows in their backs than settlers, so I can learn from the mistakes of others - this is wisdom. I was pioneering an electric supercharger setup a few years back. I found out that as voltage increased, intake manifold pressure increased logarithmically. Long story short, I ended up overvolting and destroying a couple of high dollar rare earth magnet motors in my quest for boost. Heck, education costs money, no? 

Thanks for your advise,

Chip

[TheLongWayHome]

34 minutes ago, sushidog said:

Which Hybrid battery packs would you recommend I look at?

 

Chip,

A presentation from one of the members here:-

http://eastcoasthdtrally.com/wp-content/uploads/2017/04/ECR-2017-Lithium-Battery-System.pdf

 

[sushidog]

Thanks, LongWay!

He used the battery from a Fiat. Six of these  http://www.ebay.com/itm/24V-64Ah-Fiat-500e-TESTED-Lithium-Ion-Golf-Cart-battery-/222419957522?hash=item33c9433712:g:EcgAAOSwbiFZUti9&vxp=mtr would be under $2,600 - about half the price of new. Now that's in the price range that makes it economically feasible.192 AH (153 useable) at 48v is perfect for my needs. I've got to learn a lot more about a BMS for it though.

Chip

 

[TheLongWayHome]

6 hours ago, sushidog said:

Thanks, LongWay!

He used the battery from a Fiat. Six of these  http://www.ebay.com/itm/24V-64Ah-Fiat-500e-TESTED-Lithium-Ion-Golf-Cart-battery-/222419957522?hash=item33c9433712:g:EcgAAOSwbiFZUti9&vxp=mtr would be under $2,600 - about half the price of new. Now that's in the price range that makes it economically feasible.192 AH (153 useable) at 48v is perfect for my needs. I've got to learn a lot more about a BMS for it though.

Chip

 

Chip,

If you want to see it for real and talk with the designer/implementer, come to Hutchinson, KS from Oct 8-14 (Actually Monday 9th, afternoon for the Lithium Ion battery system!) for the National HDT Rally - http://nationalhdtrally.com/2017-national-hdt-rally-registration/

Sign up before Sept 1st and get a better price and a tee shirt!!! You don't need an HDT (I don't have one) to attend.  There is also a presentation on a mini-split cooling system, which was the original OP subject matter, and is on the same afternoon. If you can only attend one day, that would be it. Then there is all those big shiny HDTs and RVs!!!!!

If you can find the "right" salvage yard, you can cut out the ebay middle man and save some more money!!

Gerry

 

 

 

[sushidog]

Thanks for the invite, Gerry.

Unfortunately I will need to be working those dates at the Shrimp Fest in Gulf Shores, AL. If not, I would have liked to attend it.

Chip

[Steve from SoCal]

I was curious about DC mini splits and ran across this, http://www.hotspotenergy.com/DC-air-conditioner/DC-AC-Complete-Systems.php

 

It is smaller than the truck unit but, a couple of these in an RV should be just fine, a truck is not as well insulated as an RV in general.    One thing about the system above, there is no DC-AC-DC conversion loss.    I use inverter drives on several machines, all my inverters are 3 phase because single phase is a poor starting point for DC rectification.     I may try one of these in my truck with a battery bank,    I have looked at window air units with an inverter as a cheap solution, lots of comments about vibration and longevity but, real cheap to replace?

 

Steve 

[noteven]

Have you guys and gals seen my analog complete rig shade cloth deployment system? Wind has way less terror effect on shade cloth than solid tarp awnings. 

It's currently on file along with the radiant reflective heat barrier and double insulation, interior ventilation air exchanger, and low voltage hydronic heating and monocoque frameless trailer that encloses all systems inside the heated envelope. 

[TheLongWayHome]

16 minutes ago, noteven said:

Have you guys and gals seen my analog complete rig shade cloth deployment system? Wind has way less terror effect on shade cloth than solid tarp awnings. 

It's currently on file along with the radiant reflective heat barrier and double insulation, interior ventilation air exchanger, and low voltage hydronic heating and monocoque frameless trailer that encloses all systems inside the heated envelope. 

Got a link?

[sushidog]

On 8/28/2017 at 10:37 PM, Steve from SoCal said:

I was curious about DC mini splits and ran across this, http://www.hotspotenergy.com/DC-air-conditioner/DC-AC-Complete-Systems.php

 

It is smaller than the truck unit but, a couple of these in an RV should be just fine, a truck is not as well insulated as an RV in general.    One thing about the system above, there is no DC-AC-DC conversion loss.    I use inverter drives on several machines, all my inverters are 3 phase because single phase is a poor starting point for DC rectification.     I may try one of these in my truck with a battery bank,    I have looked at window air units with an inverter as a cheap solution, lots of comments about vibration and longevity but, real cheap to replace?

 

Steve 

Yep, that's a pretty efficient AC, with an EER of 19.3 according to their spec sheet.  http://www.hotspotenergy.com/DC-air-conditioner/Specs-DC48.pdf

The unit I linked to is also a 48v DC heat pump with an EER of 21.43. http://www.geinnovations.net/HSAC_Productline.html

Both are very similar units, but the higher the EER the better.

Chip

[Dan Hannah]

My Prius has electric AC, I am told.  It seems like it would be powerful enough for the just the bedroom of the RV while sleeping, and it definitely would be quieter than running the genny all night.

 

Is there anything to this idea?

[Kirk W]

6 hours ago, Dan Hannah said:

Is there anything to this idea?

Your Prius has far larger battery capacity than most RVs and even then could you run it all night without the engine running? 

[Al F]

The gas engine may run all the time the air conditioner is on.  If the gas engine doesn't run all the time, the air conditioner discharging the battery faster than normal will cause the gas engine to run to keep the battery charged.

[sandsys]

18 hours ago, Al F said:

The gas engine may run all the time the air conditioner is on.  If the gas engine doesn't run all the time, the air conditioner discharging the battery faster than normal will cause the gas engine to run to keep the battery charged.

Suanne camps in her Prius for extended trips. She says with the A/C on the engine runs about 4 minutes out of every 35 minutes. Details here: http://www.cheaprvliving.com/other-conversions/living-prius/

Linda Sand

[Al F]

16 minutes ago, sandsys said:

Suanne camps in her Prius for extended trips. She says with the A/C on the engine runs about 4 minutes out of every 35 minutes. Details here: http://www.cheaprvliving.com/other-conversions/living-prius/

Linda Sand

That is amazingly efficient, the engine running less than 8 minutes an hour to charge the battery while running the A/C. Good to know.

[Al F]

3 hours ago, sandsys said:

Suanne camps in her Prius for extended trips. She says with the A/C on the engine runs about 4 minutes out of every 35 minutes. Details here: http://www.cheaprvliving.com/other-conversions/living-prius/

Linda Sand

Linda,

Thanks for the info and the link to an amazing way to travel in a very small RV.  It is wonderful the different ways people find to travel this scenic country of ours on a very economical budget. 

We love to travel.  What we love about RV'ing travel, especially when your RV is self contained with adequate battery power and solar panels, is the freedom you have to go where you want, when you want, stay as long as you wish and then move on.

The skeptic in me, checked with our son who owns a Prius, about the A/C and engine running.  He confirms that running the A/C overnight would indeed work very well.  He has never tested how long the A/C would run before the engine would start, but felt very comfortable with 20-25 minutes between running.  I take that as confirmation of the 4 minutes every 35 minutes.  A lot depends on the outside temp, how cool you want the interior of Prius, etc.  

[sandsys]

5 hours ago, Al F said:

Linda,

Thanks for the info and the link to an amazing way to travel in a very small RV.  It is wonderful the different ways people find to travel this scenic country of ours on a very economical budget. 

You're welcome. Sometime we stumble across something unique and can actually remember it later when someone asks.

Linda

[Dan Hannah]

I see a project developing here....  Bedroom AC using a Prius compressor.

I wonder how many volts the compressor takes?  There are some EXTREMELY high voltages running around a Prius.

[lappir]

Following.