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 > Just curious - why Lithiums are so heavy?

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Almot

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Posted: 01/04/18 06:18pm Link  |  Quote  |  Print  |  Notify Moderator

100 AH, flooded, 66-69 lbs.
100 AH, Li, 29-31 lbs.

Brain-dead sellers jumping on a new bandwagon, "One-fifth the weight of a traditional battery", yahooo....

More usable capacity, yes, but not 2 or 3 times more. 70-75% of Li vs 50% of flooded, this is 1.4-1.5 times more capacity.

I'm curious, is there any drop-in Gr31 Lithium, 12V, with BMS, that weighs less than 25 lbs?

GordonThree

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Posted: 01/04/18 06:32pm Link  |  Quote  |  Print  |  Notify Moderator

Is that a lithium iron battery? I've read 80% capacity at a minimum, more depending on chemistry and management.


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John & Angela

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Posted: 01/04/18 07:02pm Link  |  Quote  |  Print  |  Notify Moderator

Almot wrote:

100 AH, flooded, 66-69 lbs.
100 AH, Li, 29-31 lbs.

Brain-dead sellers jumping on a new bandwagon, "One-fifth the weight of a traditional battery", yahooo....

More usable capacity, yes, but not 2 or 3 times more. 70-75% of Li vs 50% of flooded, this is 1.4-1.5 times more capacity.

I'm curious, is there any drop-in Gr31 Lithium, 12V, with BMS, that weighs less than 25 lbs?


Both our cars are Electric.

I don’t know if I would do it all the time but we run our cars down to 5 to 10 percent once in awhile when we make a certain trip and don’t want to stop at a DC fast charge for twenty minutes. The cars don’t seem to care. Probably only a few times a year but that would probably be the same in the RV world.

I haven’t looked into it much. Are the RV lithium ion batts ok with standard RV converters? What does a group 31 lithium ion cost nowadays.


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Almot

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Posted: 01/04/18 07:14pm Link  |  Quote  |  Print  |  Notify Moderator

Electric car battery works in different conditions, it has (I think) liquid cooling system that drop-in batts don't.

I'm not sure it really goes down to 5%, what you see on display is not necessarily it, they might show you only % of a "usable charge", but I don't have electric car. Common recommendation for drop-in 12V Li, and 24-36-48 batts of scooters, ebikes etc is running it in 20%-90% SOC.

Quote:

Are the RV lithium ion batts ok with standard RV converters?

It needs slightly higher bulk voltage, and Float voltage is zero - charging must stop when full. But let's not deviate.

So... Anybody saw 20 lbs Gr31? [emoticon]

MrWizard

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Posted: 01/04/18 07:45pm Link  |  Quote  |  Print  |  Notify Moderator

Charger voltage depends on the number of series cells and the cell chemistry
The avg new 14+v converter is to high for a 3* 3.7v setup
The liFePos are 3.2v per cell and use four cells in series
4*3.2v

An inexpensive 100 ampHr 12v LiFe made from 18 cells of Chevy volt battery

Is $400
A car box drop in is around $900

* This post was edited 01/05/18 09:40am by MrWizard *


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2oldman

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Posted: 01/04/18 08:00pm Link  |  Quote  |  Print  |  Notify Moderator

Almot wrote:

I'm curious, is there any drop-in Gr31 Lithium, 12V, with BMS, that weighs less than 25 lbs?
Probably not one you'd be willing to pay a grand for.

Can't say I've heard too much complaining about their weight.

John & Angela

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Posted: 01/04/18 09:03pm Link  |  Quote  |  Print  |  Notify Moderator

Almot wrote:

Electric car battery works in different conditions, it has (I think) liquid cooling system that drop-in batts don't.

I'm not sure it really goes down to 5%, what you see on display is not necessarily it, they might show you only % of a "usable charge", but I don't have electric car. Common recommendation for drop-in 12V Li, and 24-36-48 batts of scooters, ebikes etc is running it in 20%-90% SOC.

Quote:

Are the RV lithium ion batts ok with standard RV converters?

It needs slightly higher bulk voltage, and Float voltage is zero - charging must stop when full. But let's not deviate.

So... Anybody saw 20 lbs Gr31? [emoticon]


I think I remember reading that. When my car turtles (is completely dead) its not actually dead. The BMS controls that I believe. I have never turtled either car so don't actually know what happens.

Isaac-1

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Posted: 01/05/18 04:22am Link  |  Quote  |  Print  |  Notify Moderator

Here is one that is 28 pounds http://www.lifebluebattery.com/order-lifeblue-lithium-rv-battery/100ah-lifeblue-lithium-rv-battery.html it even has built in a bluetooth connected BMS

MEXICOWANDERER

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Posted: 01/05/18 05:54am Link  |  Quote  |  Print  |  Notify Moderator

I don’t know if I would do it all the time but we run our cars down to 5 to 10 percent once in awhile when we make a certain trip

Is this not what you are ALLOWED to take from the battery and not the same thing as ADVERTISED ampere hours on individual Li-ion batteries?

Is there not a chart that explains depth of discharge of a Li-Ion battery versus expected cycle life? I seem to be having trouble finding one...

Itinerant1

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Posted: 01/05/18 06:33am Link  |  Quote  |  Print  |  Notify Moderator

Mex possibly from here? ...Battery University lithium


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