FitRV's lithium/alternator/inverter setup

[wincrasher]

That's what I was talking about.

These pictures show it with the plastic belly pan removed. This stock pan is bowed out and doesn't fully cover the alternator when it's put back in place.

[wincrasher]

Here's the info on the lithionics battery. Note it says individual cell monitoring for voltage & temp.

http://lithionicsbattery.com/wp-cont...-CTRL400-1.pdf

[wincrasher]

Originally Posted by Davydd

If you think the air conditioning was running in northern Minnesota last week which was about perfect weather wise you had to be a real wimp.

LOL. No, we were in Iowa at the time and it was 100+ with stifling humidity. I didn't need my AC at all the week we were in Minnesota.

[gregmchugh]

Originally Posted by wincrasher

Here's the info on the lithionics battery. Note it says individual cell monitoring for voltage & temp.

http://lithionicsbattery.com/wp-cont...-CTRL400-1.pdf

Both Lithionics and Victron make rugged, high quality, and reliable lithium battery systems. You do pay more for these systems and they are likely worth it but how many people are going to pay that premium for a system in an RV vs a marine application?

AM Solar is now selling Victron lithium batteries instead of building their own...

[cruising7388]

Originally Posted by booster

The BMS probably wouldn't be measuring current and wouldn't trip until the voltage dropped. By then the relay contacts could be fried or something else melted.

Considering that the energy density of these puppies is approaching a hand grenade, I would think something might be set afire before there was a sufficient voltage drop to effect shut down.

Couldn't the BMS measure excess current indirectly? Assuming the system includes balancing, during normal discharge, the voltage differential between cells is very low. But during excessive discharge rates, this differential increases significantly. Couldn't the BMS set a threshold for this differential to provide the logic for a shut down command? Wouldn't this provide protection for both external and internal shorts?

[Jostalli]

I need my AC on in San Diego and it's 75 degrees. If you've got it use it.

[tex4judy]

FitRV sent his newsletter with this article tonight:

Our Generator-Free RV – Lithium Battery, Solar, Alternator, and Inverter

It's pretty much everything I stumbled onto. And what we're installing. It was encouraging to read his test of the battery powered AC. And that the system worked as described. It's probably not for everybody, but it looks like it will accomplish our goal of not propane and no generator.

[booster]

Maybe I missed it, but what are they using for heat if they have no propane?

[tex4judy]

The Espar unit that burns diesel, taken from the secondary fuel line provided on Mercedes fuel tanks, and produces hot water, cabin heat, and engine preheating for cold weather starts. I bought mine from the distributor in Idaho - Rixen - that was recommended by Avanti. That's what we're doing.

FitRV may still have propane, but at the end of the article he described the radiant induction cook top he is testing - presumably to eliminate the propane stove. His newsletter described eliminating the generator. We also want to avoid propane.

[gregmchugh]

Originally Posted by booster

Maybe I missed it, but what are they using for heat if they have no propane?

I believe they still have a propane fueled Truma heat and hot water system.

[BBQ]

.

He only has 420Ah of batteries. That's a tall order for induction cooktop in addition to aircon.

I can't wait to see him adding more batteries, and to see how he manages the vampire draw that caused so much headache to RT.

[booster]

It was interesting that the add on alternator appeared to be a rewound factory case style instead of the one of the dedicated case DC Power units that Nations uses on many of their other units.

I hadn't heard of the controller that turns off the alternator before, and that is a very good thing to have.

I also think they are going to find out that they will come up short of capacity with battery bank, but a lot of that will be determined by how long they sit in one spot, and if engine idling is not an issue for that spot. They said they don't mind idling the engine once in a while, but that may become tedious.

With all their writing and computer use, they must also use quite a bit besides the big draws. Have they ever mentioned what their typical daily use is?

All of this is starting to look like the beginning of a bit of shift in how things are looked at in the RV world. When they all started talking about AC off the batteries, it was assumed huge battery banks and driving often was about the only way it would add up. Now, probably started by the Zion smaller bank setup, we are starting to hear about repeatedly idling over a day to get AC and recharge a smaller bank. If this trend continues, I expect we will see a lot more no idling rules campgrounds.

[tex4judy]

Yes, our discussion was similar. James / FitRV says that his goal was 3 hours of AC. Our first thought was that if we were stopping for the night and needed the AC we would get plugged in.

Since then, we've added a 500/5,000 lb trailer hitch to our construction program. For hunting trips into western NM, on the edge of the Gila Wilderness, will probably bring a trailer for the ATV, generator, etc. Bow seasons are during warmer months, rifle seasons not so much. But that is one possible solution for some of our summer trips.

Many of our trips are to Northern NM - so a 4 hour summer trip to Santa Fe would start in hot, desert weather and end in pleasant mountain air. We're thinking that the alternator/AC will take good care of that.

All decisions are a compromise, will be interesting to see how the RV market will respond to new possibilities.

[Davydd]

Originally Posted by BBQ

.

He only has 420Ah of batteries. That's a tall order for induction cooktop in addition to aircon.

I can't wait to see him adding more batteries, and to see how he manages the vampire draw that caused so much headache to RT.

In every day situations 420ah of lithium ion batteries is not a tall order especially with a fast recharging under hood second alternator. They charge faster than Onan generators or shore power. It is enough. Yes, and you can run air conditioning as well. Considering many of us rarely use an air conditioner or use one for a very short time it makes a lot of sense.

Not all of us have a "vampire" draw on our lithium ion batteries. That is a Roadtrek only problem from everything I have read.

Electric induction cooking is fast and efficient. A typical one pot meal if you have one burner does not draw that much down on the batteries. A meal might be anywhere from 20-30ah draw down.

[BBQ]

Originally Posted by Davydd

In every day situations 420ah of lithium ion batteries is not a tall order especially with a fast recharging under hood second alternator. They charge faster than Onan generators or shore power. It is enough. Yes, and you can run air conditioning as well. Considering many of us rarely use an air conditioner or use one for a very short time it makes a lot of sense.

Not all of us have a "vampire" draw on our lithium ion batteries. That is a Roadtrek only problem from everything I have read.

Electric induction cooking is fast and efficient. A typical one pot meal if you have one burner does not draw that much down on the batteries. A meal might be anywhere from 20-30ah draw down.

FitRV is planning to run the aircon for 3+ hrs at a time, and adding the cooktop, that's why I thought it is a tall order. You are right, for most people, in every day situations 420ah of lithium ion batteries is plenty.

[B Eventually]

420Ah should be plenty for James and Stef. In the article, James mentions that they've only put 13 hours on their generator in the past year and most of that was from exercising the generator.

They love their Truma, so that's not going anywhere. In the article, they mention propane capacity is the biggest limiting factor on their winter camping. So induction is a no brainer. They'll also be able to save a bit running the fridge off the inverter when they are driving.

We recently had AM Solar work their magic on our Trend. Due to weight constraints, we were limited to 180Ah which is more than enough given our touring pace. I'm sure they will find they have plenty of power unless they decide to start leaving the fridge running off the inverter over night.

[B Eventually]

Originally Posted by BBQ

FitRV is planning to run the aircon for 3+ hrs at a time, and adding the cooktop, that's why I thought it is a tall order. You are right, for most people, in every day situations 420ah of lithium ion batteries is plenty.

The three hour goal should be achievable with their setup. That's the longest time they might use AC.. They'd also have 300 watts of solar that wasn't a big factor in their AC runtime test (that alone is probably enough to run their fridge off the inverter during the day). At the end of the 3 hours, just picking James up and driving to their next stop would recharge their lithium bank in a little over an hour.

Originally Posted by The FitRV

Our goal with the battery and inverter setup is to run the air conditioner for three hours without having to run the vehicle. Three hours represents the longest race I typically compete in (during which Stef might be stuck hanging back in the RV). It’s also about an hour longer than we ever ran the generator at once during our first year in the Travato. After three hours, we’d be fine to run the engine for a while to recharge.

[Davydd]

Originally Posted by BBQ

FitRV is planning to run the aircon for 3+ hrs at a time, and adding the cooktop, that's why I thought it is a tall order. You are right, for most people, in every day situations 420ah of lithium ion batteries is plenty.

It is plenty for them as well. I'm speaking here from experience and not speculation. As Transit said, if all they did was run an Onan generator for 14 hours last year their off-grid air conditioning needs probably are not that great. 3 hours is an estimate not a tall order and I think they have a balanced view of what they want to accomplish. You don't cook all day long with an induction cooktop. It is available and with the use I mentioned you still have a potential of three hours of air conditioning.

[mojoman]

The induction cook top heats much faster than a propane stove. I amazed me how fast you can bring something to a boil. We have a small pressure cooker we use which speeds cooking and conserves power and less condensation in the van. I also installed a inverter microwave which also cooks faster or can be adjusted to lower power consumption rather than the conventional ones that cycle on and off at high power.

[gregmchugh]

Originally Posted by BBQ

.

I can't wait to see him adding more batteries, and to see how he manages the vampire draw that caused so much headache to RT.

The vampire draw is by all reports unique to the Roadtrek implementation and surely in no way inherent in a lithium battery system. It will be interesting to see if and when Roadtrek resolves this issue, I can't see how they can continue having this deficiency, especially when they start installing Ecotreks in Hymer branded vans, I wouldn't think that would be acceptable to Hymer...