RoadTrek's EcoTrek

[booster]

Originally Posted by gerrym51

Mumkin-2 volt agm batteries give you 110 usuable amp hours. you would be picking up some with a 200 lithium but i would think 400 will be more efficacious.

Roadtrek appears to use two 95ah 12v batteries if you get the optional second one in the 170, so Mumkin would have 190ah total. Taking them to 80% down would give about 150 usable. I think that is pretty reasonable to do, when compared to the lithium costs, and replacing them isn't all the spendy if you do wreck them. To each their own.

[gerrym51]

Originally Posted by booster

Roadtrek appears to use two 95ah 12v batteries if you get the optional second one in the 170, so Mumkin would have 190ah total. Taking them to 80% down would give about 150 usable. I think that is pretty reasonable to do, when compared to the lithium costs, and replacing them isn't all the spendy if you do wreck them. To each their own.

isn,t taking standard agm's down to 20 percent on a steady basis bad

[avanti]

Originally Posted by gerrym51

isn,t taking standard agm's down to 20 percent on a steady basis bad

Yes, but the point being made is that if you step back and look at the total cost of ownership, there are definitely scenarios in which purposely abusing AGMs and replacing them when needed may be the cheapest option.

[wincrasher]

I think you all are assuming some things.

If they label it a 200 ah lithium, is that the true total capacity, or is it the useable capacity - so it's really a 220 ah? Or is it something else?

[booster]

Roadtrek will always list a spec to look the best for them, regardless of it is deceptive, so in this case it would be 200ah if they say that, as there is no way to claim it bigger, unless they did the "amp" reading like they did on the zion.

[markopolo]

For pricing ideas I just took a look at Balqon's store and their RV battery packs. http://www.balqon.com/online-store/#...&sort=priceAsc They have 4 RV battery packs with BMS.

160 AH $1,510
400 AH $2,950
750 AH $4,480
1400 AH $8,150

This is good info:

Comparing and determining your energy needs in an RV application is a key factor to selection of proper size battery. Lead acid batteries are generally rated on 20 hour discharge cycle, while lithium batteries are rated on an one hour discharge rate which makes it difficult to determine the proper equivalent size of lithium battery to purchase.

They go on to say:

As an example a typical 12 Volt flooded lead acid battery rated at 155 amp hour rate has an actual rating of 113 amp hours in a five hour rating (a typical use cycle of an RV). If the application required removal of 50 amps continuous the actual battery rating is only 80 amp hours. A 2 kWhr lithium battery pack with 160 amp hour battery cells would have 160 amp hour capacity for the same draw of 50 amps continuous, which would be double the capacity of lead acid battery pack.

On the biggest Lithium Iron Phosphate RV pack, their pricing is down to $0.45 per watt hour. I think AGM's are around $0.20 per watt hour!

You have to wonder how many RV's at this years Hershey Show will have lithium batteries.

[gerrym51]

Originally Posted by Nomad32

Here is a link to a window sticker on a 210 Popular with an 800 system:

http://americanrv.com/sites/american...iles/10324.pdf

Nomad 32. the refrigerator does not look like a 3 way in this 210. it looks like the 5 cubic foot compressor fridge in my zion. there is no bottom vent outside like for the 3 way

[wincrasher]

Originally Posted by markopolo

For pricing ideas I just took a look at Balqon's store and their RV battery packs. http://www.balqon.com/online-store/#...&sort=priceAsc They have 4 RV battery packs with BMS.

160 AH $1,510
400 AH $2,950
750 AH $4,480
1400 AH $8,150

This is good info:



They go on to say:



On the biggest Lithium Iron Phosphate RV pack, their pricing is down to $0.45 per watt hour. I think AGM's are around $0.20 per watt hour!

You have to wonder how many RV's at this years Hershey Show will have lithium batteries.

Wow - each mounted in a custom steel enclosure. Adds weight, but it all looks professional grade.

[booster]

"Comparing and determining your energy needs in an RV application is a key factor to selection of proper size battery. Lead acid batteries are generally rated on 20 hour discharge cycle, while lithium batteries are rated on an one hour discharge rate which makes it difficult to determine the proper equivalent size of lithium battery to purchase.

As an example a typical 12 Volt flooded lead acid battery rated at 155 amp hour rate has an actual rating of 113 amp hours in a five hour rating (a typical use cycle of an RV). If the application required removal of 50 amps continuous the actual battery rating is only 80 amp hours. A 2 kWhr lithium battery pack with 160 amp hour battery cells would have 160 amp hour capacity for the same draw of 50 amps continuous, which would be double the capacity of lead acid battery pack."

I have seen this or similar statement several places, and truly don't understand it. Yep, they are rated at different discharge rates by time, but which is slanted to look the best?--maybe both?. Lithium gives up charge quickly and efficiently, wet cells are great at giving up charge slowly over a long time. The statement takes the lead acid battery out if its preferred spot to run at 20 hours and compares it to the lithium at 1-3-5 hours, but doesn't compare them the other way. Is it because lithium would lose capacity at slower discharge?--not stated.

They also say that the 5 hour rate is closer to what RV use is, which is nowhere near what we see, and I would guess few others would either. The example would be about a 3 hour rate. How many folks go flat in 5 hours, or even 20 hours for that matter. Our usage is more typical of a 100 hour rating. Since most folks are able to go a day or two on batteries, typical RV would more likely be 36-48 hours, I would think, and that is going totally flat. A 50 amp discharge for more than a few minutes is pretty hefty for most of us. That would be a 4 hour rate for a 200ah bank.

I wish we could see some test data at 1-5-20-100 hour rates between the 3 types (lithium, AGM, wet). I just have a feeling there is some information that is not being put out, that would be very interesting to see. Can't say which way it would lead, but would be very useful.

[gerrym51]

they all say indoor use only-what does that mean-besides the obvious-no outside underneath mounting?

[gerrym51]

Originally Posted by booster

"Comparing and determining your energy needs in an RV application is a key factor to selection of proper size battery. Lead acid batteries are generally rated on 20 hour discharge cycle, while lithium batteries are rated on an one hour discharge rate which makes it difficult to determine the proper equivalent size of lithium battery to purchase.

As an example a typical 12 Volt flooded lead acid battery rated at 155 amp hour rate has an actual rating of 113 amp hours in a five hour rating (a typical use cycle of an RV). If the application required removal of 50 amps continuous the actual battery rating is only 80 amp hours. A 2 kWhr lithium battery pack with 160 amp hour battery cells would have 160 amp hour capacity for the same draw of 50 amps continuous, which would be double the capacity of lead acid battery pack."

I have seen this or similar statement several places, and truly don't understand it. Yep, they are rated at different discharge rates by time, but which is slanted to look the best?--maybe both?. Lithium gives up charge quickly and efficiently, wet cells are great at giving up charge slowly over a long time. The statement takes the lead acid battery out if its preferred spot to run at 20 hours and compares it to the lithium at 1-3-5 hours, but doesn't compare them the other way. Is it because lithium would lose capacity at slower discharge?--not stated.

They also say that the 5 hour rate is closer to what RV use is, which is nowhere near what we see, and I would guess few others would either. The example would be about a 3 hour rate. How many folks go flat in 5 hours, or even 20 hours for that matter. Our usage is more typical of a 100 hour rating. Since most folks are able to go a day or two on batteries, typical RV would more likely be 36-48 hours, I would think, and that is going totally flat. A 50 amp discharge for more than a few minutes is pretty hefty for most of us. That would be a 4 hour rate for a 200ah bank.

I wish we could see some test data at 1-5-20-100 hour rates between the 3 types (lithium, AGM, wet). I just have a feeling there is some information that is not being put out, that would be very interesting to see. Can't say which way it would lead, but would be very useful.

isn't this Peukerts law-the faster the amps are withdrawn the less capacity a battery actually has-i;ve seen this several times when i was researching tppl agm

[booster]

I think that is what we don't know-does Peukert apply to lithium in the same way it does lead-acid?

[booster]

The info I found in a quick look would put Peukert at about 1.00 for lithium, so it would have the same capacity at all normal discharge rates.

So--rough example

100ah batteries in lithium and lead acid

At 1 hour rate lithium 100ah lead acid maybe 85ah

At 5 hour rate lithium 100ah lead acid maybe 92ah

At 20 hour rate lithium 100ah lead acid 100ah

At 100 hour rate lithium 100ah lead acid 115 hours

Which gives the most amp hours per rating would depend entirely how you use them. For us at 100 hour rating use, we would gain 10-15% with lead acid.

[Davydd]

Originally Posted by gerrym51

they all say indoor use only-what does that mean-besides the obvious-no outside underneath mounting?

Gerry, That's a CYA hedge, IMO, with the assumption inside might be a more conditioned space. However, we all know the inside of a van can get a lot warmer than the outside and Class Bs are rarely kept conditioned year round. I doubt so even with full-timers parked and letting their Bs heat up during the day while out galavanting around. And cold is cold when parked and unused inside and out.

BTW, my batteries peaked at 84F today when I checked and the inside of my B was an oven over 100F when I opened it up. That's just an anecdotal example.

You would have to keep your B self-defeatingly plugged into shore power 24/7 all year running heating and air conditioning for that recommendation to hold. Ain't gonna happen. A mobile Class B is not a fixed conditioned house.

[Davydd]

Originally Posted by booster

I think that is what we don't know-does Peukert apply to lithium in the same way it does lead-acid?

Several sources have said Peukert does not apply to lithium batteries.

[gerrym51]

Originally Posted by Davydd

Several sources have said Peukert does not apply to lithium batteries.

red alert-i agree with David. i don't think peukerts law applies to lithium or if it does not as much

[avanti]

Originally Posted by gerrym51

red alert-i agree with David. i don't think peukerts law applies to lithium or if it does not as much

Well, if you REALLY want to know:

Peukert Revisited

Summary: It's complicated.

[booster]

Originally Posted by gerrym51

red alert-i agree with David. i don't think peukerts law applies to lithium or if it does not as much

Take a look at my previous answer, where I said I found the same information and how it would apply in the real world. It may or may not be an advantage.

[Boxster1971]

In this weeks Roadtreking story from Mike Wendland he says he has 32 lithium batteries. If they are the typical 200 AH variety that means he has 1600 AH of total capacity at 12 volts. Mike's comments on being energy independent sound a lot like David's posts on performance of his ARV.

[gerrym51]

Originally Posted by Boxster1971

In this weeks Roadtreking story from Mike Wendland he says he has 32 lithium batteries. If they are the typical 200 AH variety that means he has 1600 AH of total capacity at 12 volts. Mike's comments on being energy independent sound a lot like David's posts on performance of his ARV.

does this mean they are making 6 volt battery packs? just wondering