Good Sam Club Open Roads Forum: Just curious - why Lithiums are so heavy?
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 > Just curious - why Lithiums are so heavy?

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dougrainer

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Posted: 01/05/18 06:40am Link  |  Quote  |  Print  |  Notify Moderator

AGM and Lithium batteries are heavier due to there is NO space between the plates for the electrolyte. So, the battery case is completely full of the lead type plates. Go to a battery store and pick up a 24 series lead acid deep cycle battery and then pick up the same 24 series AGM. You will be surprised at how much heavier the AGM is. Doug

valhalla360

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Posted: 01/05/18 07:59am 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?


When they talk about 2-3 times more are they talking about per pound of battery as opposed to the rated amp-hrs.


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theoldwizard1

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Posted: 01/05/18 08:06am 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.

Some do. Most do NOT.

John & Angela

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Posted: 01/05/18 08:07am Link  |  Quote  |  Print  |  Notify Moderator

MEXICOWANDERER wrote:

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...


Yah. Think you are right. Dead is not dead. Just a limit set by the car company. I don't know what percentage that is though. I think the car starts to limit as well at the end, or at least the one does. Kind of a last ditch effort to save power. It allows one restart after it turtles so you can move to the edge of the road. Maybe a kilometer. Like I say. Hasn't happened to us yet but I have read stories on the other forum.


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theoldwizard1

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Posted: 01/05/18 08:10am Link  |  Quote  |  Print  |  Notify Moderator

dougrainer wrote:

AGM and Lithium batteries are heavier due to there is NO space between the plates for the electrolyte. So, the battery case is completely full of the lead type plates. Go to a battery store and pick up a 24 series lead acid deep cycle battery and then pick up the same 24 series AGM. You will be surprised at how much heavier the AGM is. Doug

Although it is difficult to find, deep cycle batteries of the same size as a regular flooded battery also weigh more.

Quick rule of thumb for the same sized batteries. More lead = more weight = more GOOD !

theoldwizard1

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Posted: 01/05/18 08:12am Link  |  Quote  |  Print  |  Notify Moderator

MrWizard wrote:

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

I would add, I would not consider anything else but a LiFePO lithium battery.

2oldman

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Posted: 01/05/18 08:24am Link  |  Quote  |  Print  |  Notify Moderator

dougrainer wrote:

AGM and Lithium batteries are heavier due to there is NO space between the plates for the electrolyte.
Huh?

MrWizard

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Posted: 01/05/18 09:42am Link  |  Quote  |  Print  |  Notify Moderator

Chevy volt cells are liquid cooled
Tesla's Model S, also liquid cooled

Watched videos on taking them apart


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pnichols

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Posted: 01/05/18 11:58am Link  |  Quote  |  Print  |  Notify Moderator

Another "problem" with Li batteries that lead acid or classic dry cell batteries don't have is: Li batteries don't smoothly taper off voltage as they begin to need recharging - they just kindof are full voltage all the time or suddenly put out inadequate voltage right when they die.

I see this all the time with the Li batteries in my flashlights. The flashlights are either nice and bright or suddenly too dim. I prefer batteries that provide slower declining voltage values as they die.

This characteristic of Li batteries could leave some RV users suddenly power starved if their Li battery systems don't include easily accessible and understandable meters indicating how many amp hours are left in the battery bank.


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GordonThree

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Posted: 01/05/18 12:17pm Link  |  Quote  |  Print  |  Notify Moderator

pnichols wrote:

Another "problem" with Li batteries that lead acid or classic dry cell batteries don't have is: Li batteries don't smoothly taper off voltage as they begin to need recharging - they just kindof are full voltage all the time or suddenly put out inadequate voltage right when they die.

I see this all the time with the Li batteries in my flashlights. The flashlights are either nice and bright or suddenly too dim. I prefer batteries that provide slower declining voltage values as they die.

This characteristic of Li batteries could leave some RV users suddenly power starved if their Li battery systems don't include easily accessible and understandable meters indicating how many amp hours are left in the battery bank.


Very good point. Simply relying on voltage is not effective to determine state of charge for a lithium ion of any technology, including this forum's favorite the LiFePo4

Without coloumb counting, your bank could die (or rather be shut off) by the BMS at an inopportune time.

When buying a LiFePo4 pack, make sure the BMS includes an easy to use "fuel gauge", and check it frequently.


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