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Old 04-20-2016, 10:47 AM   #29
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Just to return to my original inquiry for advice. I think I can live with the OEM solar set up if the Lithium plug and play is a real option. It would provide substantially more AH for half the weight and faster charging time. It appears the Magnum with the batteries internal BMS will work fine and they are designed to work well below freezing. Am I missing something? Other than the cost.
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Old 04-20-2016, 12:27 PM   #30
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Just to return to my original inquiry for advice. I think I can live with the OEM solar set up if the Lithium plug and play is a real option. It would provide substantially more AH for half the weight and faster charging time. It appears the Magnum with the batteries internal BMS will work fine and they are designed to work well below freezing. Am I missing something? Other than the cost.
This thread is wandering more than a confused armadillo caught in this week's flood, but my short response is "it might not be that easy". Well, we have different vintages of Interstate so it gets dicey to even speculate. My husband LB_3 is working on the specs for our lithium as we speak, so that we can fully take advantage of the solar that we put in. Not only is it NOT plug and play, he's telling me that he has to physically re-wire part of the vehicle, and that's not solely because of our battery location, I don't think (it has to move from under the passenger seat where it never should have been to start with, to under the closet). Anyway, I will get him to clarify this when he has a free moment.
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Old 04-20-2016, 12:39 PM   #31
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Have you had your alternator checked? That sounds like a very slow charge rate, especially if you still have one house battery.
The issue with Lead acid batteries is that they have a high internal resistance so once they get above 85% full the charging rate drops considerably. One of the biggest advantages of Lithium batteries is that they have a low internal resistance which permits them to charge at their full amperage until full. One of my biggest frustrations with solar is getting direct sun and knowing we have 10+ amps available and the battery only taking on 2.5 amps.
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Old 04-20-2016, 01:14 PM   #32
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The two brands I'm looking at are Smartbattery and Starkpower. Both claim to be drop in replacements for lead acid and the internal BMS protects the battery from the evils of lead acid/solar charging systems.
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Old 04-20-2016, 05:09 PM   #33
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No lithium battery on the market is a true drop in replacement for lead acid batteries due to the different charging voltages and protocols. They have to be considered part of a larger system. Luckily, many inverter/chargers are flexible enough to be programmed to support Lithium batteries.

The reason a drop in won't work for us is that I want to install an inverter in our AI (30% off from Uncle Sam if it's part of a solar system) and there just isn't any practical way to run heavy enough wire to the passenger seat pedestal to hook up an inverter. That means removing the current converter, relocating the battery, and installing the inverter, and rewiring the AC power circuits.
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Old 04-20-2016, 05:29 PM   #34
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The two brands I'm looking at are Smartbattery and Starkpower. Both claim to be drop in replacements for lead acid and the internal BMS protects the battery from the evils of lead acid/solar charging systems.
I did a lot of research before I upgraded my batteries last fall. Lithium was my desired choice until I discovered that ALL lithium batteries must be above freezing to charge. They will happily discharge below freezing but can't be recharged without damage unless they are above freezing. That was a show stopper for me as I use my Interstate all year in Maryland and have been know to make winter trips to Minnesota. Smartbattery and Starkpower never mention this limitation on their web sites, but if you contact them with a direct question on charging beow freezing they will admit the limitation. See this article from Battery University for details;

http://batteryuniversity.com/learn/a...w_temperatures

- - Mike
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Old 04-20-2016, 05:38 PM   #35
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I did a lot of research before I upgraded my batteries last fall. Lithium was my desired choice until I discovered that ALL lithium batteries must be above freezing to charge.
You could install battery heaters just like your tank heaters. Added complication, perhaps, but it would extend your camping season with lithium batteries.
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Old 04-21-2016, 06:44 AM   #36
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You could install battery heaters just like your tank heaters. Added complication, perhaps, but it would extend your camping season with lithium batteries.
Heaters in general tend to draw boat-loads of power (unless they are gas) and so I'd like to see the calcs on that one.

It raises the question of whether it would be possible to have a back-up Lifeline system on a separate loop. Hibernate the lithium when it gets too cold. Quite a resource-heavy idea but if the Lifeline is there to start with and could somehow be left in place, I wonder if it could be made to work.

Back when I was in my pre-solar redneck stage of attempted boondocking, I tried to argue to my husband that we simply buy a separate Lifeline, bench charge it, and stow it in isolation under the bloody couch so that I could physically swap it out with the house battery when the house battery got too low (all I have to do in my case is lift the cushion off the passenger cab seat to access the active Lifeline). Presto - my boondocking time doubled with no extra engineering required and almost zero extra work. Sounds promising to me!

Being a mechanical engineer, my husband blanched at the inelegance of this proposal. I said, "I don't care if it's a sophisticated solution or not - all I care is whether or not it works."

Anyway, it's that general mode of thinking that makes me question whether two different battery systems could be feasible, with a possible switch-over depending on prevailing conditions.
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Old 04-21-2016, 07:34 AM   #37
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Heaters in general tend to draw boat-loads of power (unless they are gas) and so I'd like to see the calcs on that one.
I haven't run the calculations.

You can't really use tank heaters when boondocking. They're battery-killers. Since battery heaters are so similar to tank heaters, winter boondocking with battery heaters would be out of the question. But since you still need your batteries to run your 12v systems even when plugged into shore power, running battery heaters from shore power would allow you to recharge your lithium batteries even in winter.
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Old 04-21-2016, 07:54 AM   #38
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So how does Tesla get around this problem? They most certainly have cars driving around in the Nordics and I'm not aware of them shutting off regenerative braking.
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Old 04-21-2016, 09:34 AM   #39
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So how does Tesla get around this problem? They most certainly have cars driving around in the Nordics and I'm not aware of them shutting off regenerative braking.

Tesla and all other electric vehicles have a battery heating and cooling system. Remember the lithium batteries can be discharged below freezing so it is certainly drivable below freezing, with reduced range. But the batteries must be warmed up to be recharged. An EV is only recharged when plugged into a high voltage source. That source first warms the batteries before charging starts.

For my Interstate with 400 watts of solar on the roof plugging into AC shore power is a rare event when parked in my driveway. Solar keeps all my batteries fully charged every day. As I refined my battery upgrade plan the desired location for my new batteries was under the van. The complexity of trying to design and install a battery heater system was more than I wanted to take on. I chose to install four Lifeline GPL-4CT, 6V AGM batteries providing 440 AH capacity. Getting the batteries under the van, like Airstream does now on new Interstates, gave me space inside to install a 2000 watt Magnum inverter/charger without giving up any interior storage space.

My upgrades of more solar, bigger batteries and a bigger inverter has given me new freedom to go and stay where ever I want without worrying about having enough battery power to use the electrical systems for my normal needs. Now I only need to run the generator when using the air conditioner without shore power.


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Old 04-21-2016, 09:35 AM   #40
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So how does Tesla get around this problem? They most certainly have cars driving around in the Nordics and I'm not aware of them shutting off regenerative braking.


Never mind. I found the answer. The car does disable regenerative braking and they have to hear the batteries. Both which deteriorate performance. I guess I've convinced myself to stay with AGM.
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Old 04-21-2016, 10:12 AM   #41
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As I refined my battery upgrade plan the desired location for my new batteries was under the van.


- - Mike
2013 Lounge EXT on 2012 Sprinter

Thanks Mike. Do you have a photo of how you added the batteries underside? And the battery cases you used? The OEM cases on mine will require modification to go with the 6 volt batteries. I'm not sure where I could shoehorn in two more.
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Old 04-21-2016, 10:18 AM   #42
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Here is the battery sling from another thread that Boxter1971 fabbed:

http://www.airforums.com/forums/atta...6&d=1453943121
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