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Old 11-05-2020, 03:51 PM   #1
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Brand: Thor Motor Coach
Model: Axis 24.1
State: Connecticut
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Quality lithium batteries finally competitive

Price is a main factor in my interest in converting from inexpensive flooded lead acid (FLA) batteries to either AGMs or LiFePO4 batteries.

Inexpensive FLAs are available in Group 27 or 31 size with an amp hour rating of 80-100. These can be bought for about $100 each.

AGMs which have several advantages can be bought for about $200 each.

High quality, name Li batteries such as Battle Borns can be bought for about $900 each.

But there is a new sheriff in town, SOK batteries, that offers a 100 Ah Li for $599 and is sold on Amazon. The Li battery geek (don't know his name) evaluates batteries with sophisticated instrumentation and testing and he opens them up and checks out the internal BMS and assembly quality. The SOK got top marks from him. See .

As the geek notes there are lots of low cost Li batteries on the market and many of those that he has evaluated are crap. This is the first one that passes his tests with flying colors. He also evaluates another Li on this video that gets high marks and is even cheaper. But its fabricated aluminum case looks like something assembled in a garage (and like the original Apple I, probably was). I waited for the Apple II to come out and will pass on this one as well.

A pair of the SOKs should easily fit into most modest size MH battery boxes under the steps and should at least double your battery capacity. When our new Axis arrives, depending on what kind of batteries it comes with, I will strongly consider adding these.

Looks like we are finally seeing significant price movement that should make installing Li batteries much easier to swallow for all.

David
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Old 11-05-2020, 04:56 PM   #2
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Thanks for posting that VERY informative video!
Charging at minus twenty?
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Old 11-06-2020, 08:32 PM   #3
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Price dropping below $500 per kWh is quite significant if the quality of these batteries holds up over time (i.e. — many cycles) and the listed capacity is “useable”; which it appears to be.

At that price not only are lithium-iron-phosphate batteries more competitive with AGM (when likely cycle life is considered), but they make elimination of generators for some types of motorhomes a lot more practical.

For example, if the retail cost of a 4-kW Onan was applied towards extra battery capacity, a new motorhome could end up with much more useable battery capacity than what Coachmen has been installing in Cross Trek generator-less motorhomes. And if they were lithium instead of AGM, the owner wouldn’t have to worry as much about over-using the batteries.

I hope these batteries prove to be reliable, and that price keeps going down.
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Old 11-08-2020, 08:59 PM   #4
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Looking at specifications of these SOK batteries a little closer, one item that seems significantly different compared to common US brands is that recommended charge and discharge rates are lower.

The larger 206 Ah battery tested in video has a maximum continuous discharge current of 100 Amps, which could supply an inverter making approximately 1,000 Watts of power. That means that to power a typical microwave, it would take 2 of these larger batteries.

On charging side, the recommended rate is 40 Amps, with maximum of 50 Amps. That means that a fully discharged 200 Ah battery would take 5 hours to recharge (4 hours at max rate) which seems slow for lithium.

The smaller 100 Ah battery has 20A recommended, and 50A maximum, so recommended charge rate is up to 5 hours, but could be done in 2 hours. Either the type of cell, and/or the BMS, limits charge and discharge current to a lower level than I’d prefer. One of the lithium advantage is fast charging and high-power capability, and these fall a bit short in that area.

The larger 206 Ah battery is advertised at $1,029, making it only $400 per kW-hour. However, if it takes 2 batteries at a cost of over $2,000 in order to power a microwave, it may not be a great deal depending on needed energy requirement.
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Old 12-02-2020, 07:30 PM   #5
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Quote:
Originally Posted by DavidEM View Post
...cut...
A pair of the SOKs should easily fit into most modest size MH battery boxes under the steps and should at least double your battery capacity. When our new Axis arrives, depending on what kind of batteries it comes with, I will strongly consider adding these.

Looks like we are finally seeing significant price movement that should make installing Li batteries much easier to swallow for all.

David
If you add them, please reference this post. I started down this road and wasn't aware a BIM was required, mostly because it's a motorhome with an alternator.
https://www.thorforums.com/forums/sh...7&postcount=80
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