Lithium on the Cheap

[avanti]

As a single data point:
My old Airstream Interstate had no solar, and I was not very careful, so my AGM house batteries went completely dead at least 2-3 times/year. In the 8 years I owned the vehicle, I had to replace them once (probably after 5 years or so), and the replacements were still going strong when I sold the vehicle.

[Davydd]

BobB,

Your Silverleaf monitor in an Advanced RV shows the real time percent SOC in 1% increments. It shows how many amps are being withdrawn and how many amps are charging be it solar, shore power or engine alternator idle, or all three simultaneously. If you use 200ah of your battery and while driving your engine alternator and solar are putting out over 200 amps then you will know you will recharge back to 100% within an hour. That is just simple estimating. After a while you get to know pretty much what your usage will be in a given period and how long you can sit doing what you do before you have to drive or idle your engine and how long.

You also have a voltage read out and temperature of your battery bank and you can drill down and check each individual cell voltage and temperature.

[booster]

All of that information is also available from the Trimetric monitors, the monitor built into the Blue Sky solar controller, and if you have a charger with shunt controlling it will show it all also it all. They all will pick up the charging and loads from all the sources-nothing special about that.

[Boxster1971]

This is an interesting thread. I wanted bigger batteries and a 2,000 watt inverter so I can use the microwave off batteries.

I was planning to upgrade my Interstate with a 400 AH lithium pack from AM Solar. They are however not yet able to ship their batteries. They also haven't yet developed a heater system for charging in freezing temps.

Then I started researching and found the sailboat cruiser community and their wealth of info as mentioned above. I could just buy my own batteries and BMS to build a system. But then I discovered the wire from my Sprinter battery to the two AGMs in back of my van is only 4 gauge. I don't think this is adequate for charging a well depleted 400 AH lithium pack. Upgrading that wire is a big job. Interestingly the newer Airstream Interstates use a 1/0 wire to the coach batteries.

So for now I'm just going to live with my AGMs and regroup on how I might upgrade batteries and inverter in the future.

BTW - I notice on the Roadtrek Facebook posts Jim H said that the Eco-Trek includes cooling for batteries.
- - Mike

[BobB]

Originally Posted by Davydd

BobB,

Your Silverleaf monitor in an Advanced RV shows the real time percent SOC in 1% increments. It shows how many amps are being withdrawn and how many amps are charging be it solar, shore power or engine alternator idle, or all three simultaneously. If you use 200ah of your battery and while driving your engine alternator and solar are putting out over 200 amps then you will know you will recharge back to 100% within an hour. That is just simple estimating. After a while you get to know pretty much what your usage will be in a given period and how long you can sit doing what you do before you have to drive or idle your engine and how long.

You also have a voltage read out and temperature of your battery bank and you can drill down and check each individual cell voltage and temperature.

Thank you Davyyd for the info

Can you capture that data on a chip/card/computer? Is there anything that can give one a idea of the "health" , i.e remaining "life" of their battery?

OR will we just all know how well it goes in 10 years

[avanti]

Originally Posted by Boxster1971

I discovered the wire from my Sprinter battery to the two AGMs in back of my van is only 4 gauge. I don't think this is adequate for charging a well depleted 400 AH lithium pack. Upgrading that wire is a big job.

Mike, Out of curiosity, why do you see upgrading that wire as a big job? I am considering doing exactly that on my rig, and I was thinking it looked pretty easy. I was just going to run from front to back under the vehicle with a sheathed wire. Are there issues i am not seeing?

[booster]

Originally Posted by avanti

Mike, Out of curiosity, why do you see upgrading that wire as a big job? I am considering doing exactly that on my rig, and I was thinking it looked pretty easy. I was just going to run from front to back under the vehicle with a sheathed wire. Are there issues i am not seeing?

Not really missing much. It can be a pain to get around some stuff, though. The tightest spot on our Chevy was in the left front wheelwell area that the cable had to go through, along with about a billion of it close friends that were already there .

Wiring, refusing, different separator and controls, ammeter, etc under the hood were at least as much work as running the cable.

[Davydd]

Originally Posted by BobB

Thank you Davyyd for the info

Can you capture that data on a chip/card/computer? Is there anything that can give one a idea of the "health" , i.e remaining "life" of their battery?

OR will we just all know how well it goes in 10 years

All batteries lose capacity over time. I feel I have enough capacity at 800ah to still bridge that loss with little change, if any, in what I do, at least in my anticipated ownership time. I actually don't see myself owning my ARV for 10 years. Even if I stay healthy and active there will be a lot newer and better gnawing on me.

[BobB]

Originally Posted by Boxster1971

BTW - I notice on the Roadtrek Facebook posts Jim H said that the Eco-Trek includes cooling for batteries.
- - Mike

That may have something to do with some reports of decreased battery life with high temperatures.

Technomadia.com observed decreased life in their lithium batteries and posed some theories, one of which was about temperature. His manufacturer (Elite)"........ observed that a 10C (18F) temperature increase over a baseline room temperature of ~23C (74F) results in the number of lifetime cycles being cut in half."

Technomadia.com concluded - "This means at 33C (91F) usable battery life will be cut in half, and presumably to a quarter at 43C (109F). This is VERY substantial. "

Sounds like needing a well ventilated space with some kind of auto fan system if temp rises above a certain level?

This is all part of their 3.5 year lithium update on their site - very interesting reading.

[avanti]

The Tesla automotive battery pack is liquid cooled.

[BobB]

Originally Posted by avanti

The Tesla automotive battery pack is liquid cooled.

As is the new PowerWall - "liquid thermal control system". I read somewhere that it must be vertically mounted on a wall, due to this thermal system.

[eric1514]

Originally Posted by BobB

That may have something to do with some reports of decreased battery life with high temperatures.

Technomadia.com observed decreased life in their lithium batteries and posed some theories, one of which was about temperature. His manufacturer (Elite)"........ observed that a 10C (18F) temperature increase over a baseline room temperature of ~23C (74F) results in the number of lifetime cycles being cut in half."

Technomadia.com concluded - "This means at 33C (91F) usable battery life will be cut in half, and presumably to a quarter at 43C (109F). This is VERY substantial. "

Sounds like needing a well ventilated space with some kind of auto fan system if temp rises above a certain level?

This is all part of their 3.5 year lithium update on their site - very interesting reading.

It was 105 here yesterday. It will be over 100 the rest of the week. A fan will do little more than blow hot air at the batteries. Some other source of actual cooling will be needed.

[BobB]

Originally Posted by eric1514

A fan will do little more than blow hot air at the batteries. Some other source of actual cooling will be needed.

So another question for Roadtrek - how are you cooling your batteries? Probably some proprietary system they won't give details on (yet)

[Boxster1971]

Originally Posted by avanti

Mike, Out of curiosity, why do you see upgrading that wire as a big job? I am considering doing exactly that on my rig, and I was thinking it looked pretty easy. I was just going to run from front to back under the vehicle with a sheathed wire. Are there issues i am not seeing?

Hadn't thought about running the new larger wire under the vehicle. That might work - I'll have to look at that closer. Thanks for the idea - that's why this forum is so great. When one gets tunnel vision on an idea fresh thinking always helps.

[Jostalli]

Originally Posted by eric1514

It was 105 here yesterday. It will be over 100 the rest of the week. A fan will do little more than blow hot air at the batteries. Some other source of actual cooling will be needed.

A fan is a fine cooling method. This is why fans are in computers.

[markopolo]

You rely on the ambient air being cooler with fan moving air through a computer or blowing on a heatsink.

The part gets hot and you use moving air to help remove the heat.

I think with the batteries you're more concerned with the surrounding air being too warm for the batteries.

[Davydd]

The lithium ion batteries have an upper range of 149F. Like all cooling, it would be to prevent confined heat build up over ambient I would think. Like computers, refrigerators, inverters, etc. fans would be the logical inexpensive choice. I suspect I would rarely be in situations where I live and when and where I travel where my batteries will rise to the temperatures Technomadia seemed to be concerned with and not for any significant time to worry about it. I would think liquid refrigeration cooling would be an expensive overkill.

[booster]

I think the information said something like 1/2 the cycle life for every 10* C? above ambient of 25*

[mojoman]

I'm installing this in my battery cabinet to address any heat:
http://www.amazon.com/gp/product/B00...rch_detailpage

[BobB]

Originally Posted by booster

I think the information said something like 1/2 the cycle life for every 10* C? above ambient of 25*

The info on the Technomedia site was:

"Elite let me know that in their experience heat has a huge impact – even within that operating range.

They [Elite] have observed that a 10C (18F) temperature increase over a baseline room temperature of ~23C (74F) results in the number of lifetime cycles being cut in half.

This means at 33C (91F) usable battery life will be cut in half, and presumably to a quarter at 43C (109F). This is VERY substantial.

I am disappointed that the impact of temperature on GBS cells does not seem to be documented and published online anywhere (though I don’t feel it was intentionally hid either) – especially considering 110F is actually a rather common summer temperature in Phoenix Arizona where Elite is located!

Had we known this potential impact upfront, we would have definitely approached the installation differently."

Not hard to travel to non-desert areas in the summer and see temps hit 91F.