Quote:
Originally Posted by Backcountryguy
Interesting statement which seems to be borne out by all lithium sites I've visited. This statement alone makes lithium the way to go for me:
"A single GT12V 600A-8DR battery at 145 pounds will easily replace
6 units of the Concord Lifeline 255 ah 8D batteries at 1100 pounds."
Of course, this higher end battery costs in excess of $9500... Wow! If you go with one of their standard 8D lithium's (450 Ah), that price is approximately $6000.
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I hate it when vendors overly exaggerate ... lithium is good, but not that good. Especially when it isn't qualified with the comparison metric.
6 x 255ah = 1530ah of LA (Lifeline 8D LA is 255ah @ 20hr rate)
- if we use the overly conservative value of 50% DoD for an LA, that gives us 765ah of usable LA.
If we ignore current / amp draw effects for a moment (6 8D would permit a very large current draw w/o deleterious energy yield impacts) and design the system assuming a 60% DoD (knowing full well it really won't shorten usable life of LA that much) - we have 913ah.
SO: Our massive 6 x 8D pack will supply 765-913aH of usable energy with decent life cycle and a calendar life of 5-7yrs if treated properly. Most packs end up 'calendaring' out rather than cycling...so most liklely 7yrs.
A lithium ion pack is best served if DoD is ~90%. If you believe the claims that consumer level lithium will last 10yrs or more, the DoD will need to be reduced to about 75-80%. But let's use the 90% figure -> so that 600aH lithium battery is good for 540aH.
So now we are talking apples to apples. The usable capacity of that lithium battery is 540aH. The usable capacity of the lead bank is ~765ah.
A more valid comparison is the 4.2-4.5 of the 8D Lifeline LA vs a single 8D form factor from Lithionics. However, since we can't have fractional batteries, we would need a different case size. (I'd use a different form factor (smaller individual batteries) for both the LA and the Lithium ion anyway).
I saw something interesting in the Lithionics datasheet. The internal resistance of the pack is spec'd at <8mohms. This is pretty high. Looking over a few of their batteries, looks like most of them are spec'd this way. Interesting.
As side note, there is an interesting thread going on over at expeditionportal about these guys :
battleborn batteries. $900/100ah. Might be worth a look (no affiliation, no idea as to their rep or quality).
Not trying to damping your enthusiasm...I love lithium batteries and will most likely be installing a medium sized pack (~400ah) in my van too. At the moment, I will be assembling my own pack ... and even with my supply channels, the economics still do not favor a lithium. Energy density & weight will make the decision for me...
...I work in energy storage.