Aux Lithium Battery in a old non-smart Alternator vehicle?

CTL

Well-Known Member
Rob I have had a couple of those SSB batteries and were happy with them. I am going through the battery dilemma myself at the moment and trying to justify a Lithium setup. Basically you are paying a huge premium for a weight saving from what I can see
Weight saving is one benefit, consistent voltage over a lot longer period is another, greater use of capacity (DOD to 20% for lithium vs 50% for AGM) and the primary benefit for me was quicker charging for lithium (depending on manufacturer’s recommendations, up to twice as quick).
 

rob_macca67

Well-Known Member
Rob I have had a couple of those SSB batteries and were happy with them. I am going through the battery dilemma myself at the moment and trying to justify a Lithium setup. Basically you are paying a huge premium for a weight saving from what I can see
Correct and since the weight issue is not a big thing for me atm, I cannot justify outlaying the extra $$ for a Lithium...
From what I've been told a 105aH AGM & 105aH Lithium will both supply 105aH and in my low demand setup, I just cannot justify going with a Lithium yet... If I had a Caravan, etc then a Lithium would be the go then....
 

CTL

Well-Known Member
Correct and since the weight issue is not a big thing for me atm, I cannot justify outlaying the extra $$ for a Lithium...
From what I've been told a 105aH AGM & 105aH Lithium will both supply 105aH and in my low demand setup, I just cannot justify going with a Lithium yet... If I had a Caravan, etc then a Lithium would be the go then....
For longevity, you should only discharge an AGM by 50% whereas you use 80% of a lithium’s capacity. So on your example of a 105ah battery, 52aH for the AGM and 84aH for the lithium
 

McGinnis

Active Member
Correct and since the weight issue is not a big thing for me atm, I cannot justify outlaying the extra $$ for a Lithium...
From what I've been told a 105aH AGM & 105aH Lithium will both supply 105aH and in my low demand setup, I just cannot justify going with a Lithium yet... If I had a Caravan, etc then a Lithium would be the go then....

While it's strictly true that a 105Ah battery is a 105Ah battery, that idea ignores several things, including:

1. Voltage curves during discharge (a lithium battery will maintain voltage through a larger range of discharge depths). This may or may not matter in your use case.

2. The impact on the battery at various depths. If you want your AGM to last, you should avoid discharging it below APPROX 50%, giving you an effective ~52.5Ah. If you want your lithium to last, avoid discharging it below APPROX 20%, giving you an effective 81.6Ah.

Pretty big difference really, especially at half the weight. The usable energy density is dramatically different.

On another note, for longevity, don't store your lithiums at 100%.
 

rob_macca67

Well-Known Member
While it's strictly true that a 105Ah battery is a 105Ah battery, that idea ignores several things, including:

1. Voltage curves during discharge (a lithium battery will maintain voltage through a larger range of discharge depths). This may or may not matter in your use case.

2. The impact on the battery at various depths. If you want your AGM to last, you should avoid discharging it below APPROX 50%, giving you an effective ~52.5Ah. If you want your lithium to last, avoid discharging it below APPROX 20%, giving you an effective 81.6Ah.

Pretty big difference really, especially at half the weight. The usable energy density is dramatically different.

On another note, for longevity, don't store your lithiums at 100%.
True... but most 12v appliances (maybe except for a invertor) also have a built-in voltage tolerance range where they can still operate at the lower voltages... As I don't use any high current appliances, the need for a lithium (other than weight saving) is not really there for me at this point in time...
 
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