Interesting and informative article. Please note the following:
1. Statement in article: “Many LFP batteries are rated for 3,000 to 5,000 recharge cycles versus 200 to 500 recharge cycles of a LA battery – so up to 10 times the life of a Lead Acid battery”
Actual data: For a “standard” AGM deep cycle battery (This data from East Penn Manufacturing (Deka and Duracell batteries), Trojan and Odyssey.) At 50% depth of discharge, 1000 charge discharge cycles. At 100% depth of discharge (not recommended) 150 to 200 cycles. The graph of cycle life vs. number of discharge cycles expected is virtually linear from 50% to 0% depth of discharge. (This shows that the often-stated guidance to not discharge deep cycle AGM batteries below 50% state of charge is incorrect and can even reduce the total amount of energy that can be extracted from the battery over its service life.)
2. Statement in article: “You can also see a significant cost savings over the life of the battery.” Actual data Very few RV’ers, in fact almost no RV’ers, will ever save any money by converting from AGM deep-cycle house batteries to lithium ion house batteries. 2a. Very few RV’ers will exceed At 1,000 50% cycles on a given RV. 2b. For a proper conversion to just 2 lithium ion batteries from 2 AGM batteries, which includes as the article states much more than just the batteries, the cost will likely be in the $2,000 to $3,000 range for a do-it-yourself conversion and in the $ 4,000 to $6,000 price range to pay a professional to perform the conversion.
Given the high cost and the storage/use low temperature limitations, it is generally highly inadvisable to convert from deep-cycle AGM batteries to lithium ion batteries. (With the possible exception of full-time RV’ers and those who must be able to run their A/C without a connection to shore power or running their generator). If you just need more energy storage, a portable lithium ion power supply, such as a Jackery or Bluetti can be far more practical. These devices can even be used to top-off or even fully charge your AGM house batteries.
Correction: "The graph of cycle life vs. number of discharge cycles expected is virtually linear from 50% to 0% depth of discharge. " Should be: "The graph of cycle life vs. number of discharge cycles expected is virtually linear from 50% to 0% depth of charge."
As with any electronic component, what would keep the BMS from failing and allowing runaway charging to the battery and causing a fire? That’s my biggest reluctance in switching battery types.
I see numerous articles on electrical apparatus referring to being "UL Approved". UL, or Underwriters Laboratories, is only one organization that may be a Nationally Recognized Testing Laboratory (NRTL) by OSHA for a particular product category. CSA, Intertek, TUV, ETL, are examples of other NRTL's that may have certified a product, equivalent to UL. Maybe a brief article on NRTL's would be helpful to readers.
I jumped into the LiPo batteries last year. I've got two 100ah batteries, and my 700 watt solar array is controlled by a Morningstar MPPT controller. Morningstar helped me set up a custom charging program for the batteries. So far, so good. But then we got caught in sub-freezing temps on a trip from Houston to Reno recently. I've installed knife switches on the batteries to keep from attempted charging because constant charge attempts can't be good for the BMS. I also shut off the power from the solar array. If we're plugged in, the trailer just runs off the stock converter with no charging when we're in these freezing conditions. Normally we don't do winter camping but we were tossed into this unexpectedly. I think I have MY system set up now, but this was all stuff I hadn't planned on when I first got started. Live and learn.
All articles I've seen deal with the inverter charging of the batteries. My reluctance to switch, stems from questions about the charging of the batteries from the alternator on my Class A motorhome. Any info would be appreciated!
Interesting and informative article. Please note the following:
1. Statement in article: “Many LFP batteries are rated for 3,000 to 5,000 recharge cycles versus 200 to 500 recharge cycles of a LA battery – so up to 10 times the life of a Lead Acid battery”
Actual data: For a “standard” AGM deep cycle battery (This data from East Penn Manufacturing (Deka and Duracell batteries), Trojan and Odyssey.) At 50% depth of discharge, 1000 charge discharge cycles. At 100% depth of discharge (not recommended) 150 to 200 cycles. The graph of cycle life vs. number of discharge cycles expected is virtually linear from 50% to 0% depth of discharge. (This shows that the often-stated guidance to not discharge deep cycle AGM batteries below 50% state of charge is incorrect and can even reduce the total amount of energy that can be extracted from the battery over its service life.)
2. Statement in article: “You can also see a significant cost savings over the life of the battery.” Actual data Very few RV’ers, in fact almost no RV’ers, will ever save any money by converting from AGM deep-cycle house batteries to lithium ion house batteries. 2a. Very few RV’ers will exceed At 1,000 50% cycles on a given RV. 2b. For a proper conversion to just 2 lithium ion batteries from 2 AGM batteries, which includes as the article states much more than just the batteries, the cost will likely be in the $2,000 to $3,000 range for a do-it-yourself conversion and in the $ 4,000 to $6,000 price range to pay a professional to perform the conversion.
Given the high cost and the storage/use low temperature limitations, it is generally highly inadvisable to convert from deep-cycle AGM batteries to lithium ion batteries. (With the possible exception of full-time RV’ers and those who must be able to run their A/C without a connection to shore power or running their generator). If you just need more energy storage, a portable lithium ion power supply, such as a Jackery or Bluetti can be far more practical. These devices can even be used to top-off or even fully charge your AGM house batteries.
Correction: "The graph of cycle life vs. number of discharge cycles expected is virtually linear from 50% to 0% depth of discharge. " Should be: "The graph of cycle life vs. number of discharge cycles expected is virtually linear from 50% to 0% depth of charge."
As with any electronic component, what would keep the BMS from failing and allowing runaway charging to the battery and causing a fire? That’s my biggest reluctance in switching battery types.
That is a small (but real) possibility. And that’s why it’s important to only use quality components…
I see numerous articles on electrical apparatus referring to being "UL Approved". UL, or Underwriters Laboratories, is only one organization that may be a Nationally Recognized Testing Laboratory (NRTL) by OSHA for a particular product category. CSA, Intertek, TUV, ETL, are examples of other NRTL's that may have certified a product, equivalent to UL. Maybe a brief article on NRTL's would be helpful to readers.
For motorhomes, you also need to discuss alternator charging profiles.
A DC-to-DC charger will take care of all of that. It’s the best way to intermix battery chemistries.
I jumped into the LiPo batteries last year. I've got two 100ah batteries, and my 700 watt solar array is controlled by a Morningstar MPPT controller. Morningstar helped me set up a custom charging program for the batteries. So far, so good. But then we got caught in sub-freezing temps on a trip from Houston to Reno recently. I've installed knife switches on the batteries to keep from attempted charging because constant charge attempts can't be good for the BMS. I also shut off the power from the solar array. If we're plugged in, the trailer just runs off the stock converter with no charging when we're in these freezing conditions. Normally we don't do winter camping but we were tossed into this unexpectedly. I think I have MY system set up now, but this was all stuff I hadn't planned on when I first got started. Live and learn.
👍🏻
All articles I've seen deal with the inverter charging of the batteries. My reluctance to switch, stems from questions about the charging of the batteries from the alternator on my Class A motorhome. Any info would be appreciated!
You need a DC to DC charger yo do this properly. I have an article on that topic coming soon.