Battery replacement

[WOLF 1]

I have 16 Trojan l-16 6 volt batteries at 370 amp hours each, How many Battle Born 12 volt 100 amp hour lithium batteries would replace that pack? In the summer in the batteries always stay above 70% but 5 months in the winter the batteries drain to 50% discharge.

 

[Bob142]

I recommend you check out this video. Will makes a direct comparison between lead acid and lithium batteries. You should be able to do the math from there.

 

[Ped]

24

 

[WOLF 1]

I recommend you check out this video. Will makes a direct comparison between lead acid and lithium batteries. You should be able to do the math from there.

Great thank you

 

[WOLF 1]

24

Holy smokes that's not cheaper than lead acid. Thanks

 

[SCClockDr]

370 / 2 = 185 useful AH
185 X 8 (12V batteies) = 1480 AH
1480 / 90 (90% DOD) = 16.4 (17 BB 100AH 12V Batteries)

 

[Ped]

Holy smokes that's not cheaper than lead acid. Thanks

Thats just equaling your usable amperage from 80% - 20% soc. There is a bunch of variables that can allow for less batteries. You can choose to draw much deeper and you can factor your current system will charge faster, perhaps much faster, drastically lowering needed reserve. You can buy 200ah raw cells for about $650 x 9 = $5850

thats about equal to the trojans and will last realistically 3-4x longer.

 

[Bob142]

Great thank you

I think Ped's number is a worst case scenario (as they explain in their follow up). SCClockDr's seems more realistic in practice.

Based on the info at 1:25 of the video: If your Trojans are AGMs I think the equivalent BBs is 14. If they are flooded, BB equivalent is 12.

Here's how I arrived at those numbers:
From the vid: "Factoring in Coulombic Efficiency: A 100ah Lithium = 220ah AGM = 250-290ah Flooded Lead Acid"
So, normalizing your 6V lead acids to 12V (as SCClockDr does above), you have: 370 X 8 = 2,960 Ah.

• If AGM: 2,960/220 = 13.45 100Ah BBs (so 14)
• If Flooded: 2,960/250 = 11.84 100Ah BBs (so 12).

And you get 3,000-5,000 cycles at 100% capacity from the BBs.

It's worth watching the entire video to understand the total cost of ownership of LiFePO4 vs. Lead Acid. Will's coverage of the topic is comprehensive.

 

[WOLF 1]

370 / 2 = 185 useful AH
185 X 8 (12V batteies) = 1480 AH
1480 / 90 (90% DOD) = 16.4 (17 BB 100AH 12V Batteries)

Yes thank you that makes total sense you're awesome

 

[WOLF 1]

I think Ped's number is a worst case scenario (as they explain in their follow up). SCClockDr's seems more realistic in practice.

Based on the info at 1:25 of the video: If your Trojans are AGMs I think the equivalent BBs is 14. If they are flooded, BB equivalent is 12.

Here's how I arrived at those numbers:
From the vid: "Factoring in Coulombic Efficiency: A 100ah Lithium = 220ah AGM = 250-290ah Flooded Lead Acid"
So, normalizing your 6V lead acids to 12V (as SCClockDr does above), you have: 370 X 8 = 2,960 Ah.

• If AGM: 2,960/220 = 13.45 100Ah BBs (so 14)
• If Flooded: 2,960/250 = 11.84 100Ah BBs (so 12).

And you get 3,000-5,000 cycles at 100% capacity from the BBs.

It's worth watching the entire video to understand the total cost of ownership of LiFePO4 vs. Lead Acid. Will's coverage of the topic is comprehensive.

Yes l did watch the video,and I think your calculations are correct. Thank you for all the effort you put into your response?