FitRV's lithium/alternator/inverter setup

[thefitrv]

Originally Posted by wincrasher

Well, if I go undetected by JH, I'll be sure to snap some pics, and maybe a bit of video. If he chases me off, I have a backup plan that is very sneaky.

The sneaky option sounds more fun. I'd just start with that one! (I hope it involves fake moustaches...)

[rectalogic]

Originally Posted by mojoman

They are lighter than a standard microwave too.
When I need to replace my house one, I'm going to find another inverter type.

Interesting. I wonder if they could make DC native versions. Docs say "The inverter power supply circuit uses the AC line 120V, 60Hz to supply 4,000V DC to the magnetron tube." https://electronico71.files.wordpres...o-inverter.pdf

So maybe hook a 12V->4000V converter into that and avoid 12V DC->120V AC->4000V DC
http://apowerdesign.com/pdf/p3.pdf




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[avanti]

You would need a mighty big wire from your battery to the oven. I think a microwave is one of the few places in an RV where AC makes sense, given the relative short run times.

[bobojay]

Originally Posted by wincrasher

Well, if I go undetected by JH, I'll be sure to snap some pics, and maybe a bit of video. If he chases me off, I have a backup plan that is very sneaky.

Can you outrun him?

[cruising7388]

Originally Posted by booster

As long as the batteries and/or loads are drawing enough power to keep the power sources from reaching their absorption settings, all of them will be putting out what ever they can as they try to get to those settings.

Once the batteries and/or loads start requiring less power, the voltage will start to climb until the lowest setpoint is reached on one or more of the sources. Soon after that, those sources will start to drop output to try to maintain the voltage from going higher. By this point, however, you don't care if they quit contributing because you are charging at all the batteries will take, and running everything you want without their contribution.

Bottom line is that matching voltages is not a big deal to get all sources to charge at max. If you are trying to get voltage control on your charging, then you need be aware of how you set things so the best controlled source is in control of the voltage once the setpoints are reached.

I think what you're saying is that different charging sources with disparate voltages will still contribute to battery charging when those sources are operating in the bulk/constant current mode but when the sources revert to to absorption/constant voltage charging, this is no longer the case.

My own test with dual non-managed constant voltage charging sources indicated that the battery only recognizes the source presenting the higher voltage.

[booster]

Originally Posted by cruising7388

I think what you're saying is that different charging sources with disparate voltages will still contribute to battery charging when those sources are operating in the bulk/constant current mode but when the sources revert to to absorption/constant voltage charging, this is no longer the case.

My own test with dual non-managed constant voltage charging sources indicated that the battery only recognizes the source presenting the higher voltage.

In theory, what you say about recognizing the highest voltage makes sense. But in a typical case, if we have an engine generator running at 14v setpoint with 200 amps capacity, and solar at 14.3v and 15 amps capacity, it doesn't seem to pan out. We can be charging at 150 amps and maybe getting 13.8v, and if we shut off the solar we just get 140 amps at nearly the same voltage. If we shut off the alternator, we will go to 15 amps and maybe 12.5v, so obviously both have to be contributing. Once you get to the point where the loads are within the capacity of all the charging sources, then your scenario of the higher voltage source taking over is what appears to happen, as I mentioned earlier, but as soon as the load is higher than any given sources capacity, it loses that control. At that point the voltage will be stable at the voltage of the higher setpoint source, and the load will be under that sources capacity.

[wincrasher]

Originally Posted by bobojay

Can you outrun him?

If he wants to challenge me to a "heart attack sprint", then I'm up for it!

[Jostalli]

I am learning that it is all about where you plan on using your van. Davydd only travels in cooler climates and apparently FitRV does as well. We have a self-built ~R-10-12 insulated Promaster with window insulation, fantastic vent, three portable 12V fans, and a 12V Autoclima Air Conditioner. Our van is all electric with induction cooktop, convection microwave, electric heater, electric water heater. Powered by 640Ah LiFePO4 batteries. In San Diego the van performs perfectly. Now that we are on the road full time I feel I have enough experience in incredibly hot and humid temps. A month ago we finished almost 6000 miles throughout the southern United States. Today we are on the beach in Sayulita Mexico. Very few days have been more comfortable in the van versus outside. We interviewed RV's in parks we stayed in and they all said their Air Conditioners were running non-stop and many confessed that their AC's were not maintaining the temps set on the thermostats.

[avanti]

Originally Posted by Jostalli

and a 12V Autoclima Air Conditioner.

I'd love to hear more about your A/C. I am planning to upgrade to a 12V unit, but I am frozen in indecision as to which option to go with.

[Jostalli]

Originally Posted by avanti

I'd love to hear more about your A/C. I am planning to upgrade to a 12V unit, but I am frozen in indecision as to which option to go with.

I performed a rather lengthy due diligence on this subject but that was almost a year ago. I chose the Autoclima UGO 12V A/C because I did not want a huge box on the roof (I wanted to remain stealth due to our travel plans) and the mini split units available seemed to be a little kludgy. The mini split is the most ideal so if I were building a van now I would probably get the Autoclima: http://impianti.autoclima.com/en/single/1248

I mounted the Autoclima UGO in a closet. I cut two holes in the floor. One is the exhaust and one is to draw in the cooler air under the van. I cut a hole in the side of the closet that faces our sofa sleeper and mounted a vent. I ran ducting from the UGO up to the vent.

Since the UGO is only 3250Btu it is not effective at lowering the temperature inside when ambient temps are high (maybe 1-2 degrees). But, my wife and I agree that we would be so upset if it died. It is so nice to have it blowing cold air on us when we sleep. We run it on high all night.

The amp draw on high is around 40 amps.

[Davydd]

Originally Posted by Jostalli

I am learning that it is all about where you plan on using your van. Davydd only travels in cooler climates and apparently FitRV does as well. We have a self-built ~R-10-12 insulated Promaster with window insulation, fantastic vent, three portable 12V fans, and a 12V Autoclima Air Conditioner. Our van is all electric with induction cooktop, convection microwave, electric heater, electric water heater. Powered by 640Ah LiFePO4 batteries. In San Diego the van performs perfectly. Now that we are on the road full time I feel I have enough experience in incredibly hot and humid temps. A month ago we finished almost 6000 miles throughout the southern United States. Today we are on the beach in Sayulita Mexico. Very few days have been more comfortable in the van versus outside. We interviewed RV's in parks we stayed in and they all said their Air Conditioners were running non-stop and many confessed that their AC's were not maintaining the temps set on the thermostats.

I may travel in cooler climates or follow the 70 degree principle not because of what my B is capable of but what I prefer which is comfort, quietness, being outside and breathing natural air. If I had to stay inside a B running air conditioning to be comfortable I might as well stay home.

Our B is insulated better than most. One Advanced RV person has claimed running 13 hours straight on the same 800ah lithium ion battery bank I have in 90 degree temperatures. I would just hope to never get into that situation. It has happened but has been rare in our travels.

I'm generally comfortable up to 85 degrees and 90 degrees if in a dry climate. With our screen system, our window shading and reflecting system and MaxxFan we can keep the inside of our van about the same temperature as the outside. I would do that before turning on air conditioning.

High humidity, not heat, is the biggest culprit that bugs me.

[avanti]

Originally Posted by Jostalli

The mini split is the most ideal so if I were building a van now I would probably get the Autoclima: http://impianti.autoclima.com/en/single/1248

Yeah, that one is on my short list. Do you happen to have a recommendation on where and how to buy Autoclima products in the US?

Thanks!

[thefitrv]

Originally Posted by Davydd

If I had to stay inside a B running air conditioning to be comfortable I might as well stay home.

Here, here!! I think that's what's missed out in a lot of the discussion about running air conditioning off batteries. Like Davydd, we don't really want to do that.

Trust me, it's not that we don't go out when it's hot. We do. But we're usually outside doing something in those circumstances. Or, we go higher up. And, of course, we don't deliberately go to Phoneix in August or anything like that (because that's just insane).

There are times when we can't avoid the heat (or humidity to Davydd's point). Things like Forest City for this year's GNR. At those times, we relent, and plug in, and run what we need in order to survive.

[wincrasher]

I agree as well, but with a twist.

It would be a sad day if we had to stay home if it was "too hot". Many, many trips I would have to cancel if that was my attitude. And forget about taking the dog anywhere.

90% of the fun of this whole AC on batteries boondoggle is just in the attempt. Why go to the moon? Why climb a mountain? Because it's there of course!

[B Eventually]

Originally Posted by thefitrv

Here, here!! I think that's what's missed out in a lot of the discussion about running air conditioning off batteries. Like Davydd, we don't really want to do that.

Trust me, it's not that we don't go out when it's hot. We do. But we're usually outside doing something in those circumstances. Or, we go higher up. And, of course, we don't deliberately go to Phoneix in August or anything like that (because that's just insane).

There are times when we can't avoid the heat (or humidity to Davydd's point). Things like Forest City for this year's GNR. At those times, we relent, and plug in, and run what we need in order to survive.

But now you have Stef's cat to keep cool.... I suppose you could shave it and run the fan to keep the kitty cool.

[thefitrv]

Originally Posted by wincrasher

I agree as well, but with a twist.
90% of the fun of this whole AC on batteries boondoggle is just in the attempt. Why go to the moon? Why climb a mountain? Because it's there of course!

Guilty as charged!!

[thefitrv]

Originally Posted by Transit

But now you have Stef's cat to keep cool.... I suppose you could shave it and run the fan to keep the kitty cool.

Stef is determined to turn it into an "adventure cat". I don't know if she envisions it staying put in the RV much.

As for myself, I don't know if I envision it in the RV at all. :-/

[B Eventually]

Originally Posted by thefitrv

Stef is determined to turn it into an "adventure cat". I don't know if she envisions it staying put in the RV much.

As for myself, I don't know if I envision it in the RV at all. :-/

You should have told me you were in Seattle that week. I would have driven in to Seattle to visit. I could have shared about our adventures traveling with a giant dog. Maybe we could have schemed a way to get that cat back into the tree or something...

[Jostalli]

Originally Posted by avanti

Yeah, that one is on my short list. Do you happen to have a recommendation on where and how to buy Autoclima products in the US?

Thanks!

The US distributor I bought from is no longer a distributor. I would go through Badger Truck Refrigeration. They are very helpful in pre sales. They sell the IndelB line, which is their private label of the same products.

[Jostalli]

We specced our system to be able to run the A/C, fans and fridge all night with the occasional siesta. Of all of our systems I'd say the 12V A/C and 640Ah LiFePO4 batteries are what we appreciate most. Especially sitting here now in Mexico where the low is 80 with 80% humidity.