# Leaf Battery capacity



## Mark F (Aug 13, 2011)

What would the kwh capacity of a Leaf Battery be if it was broken down into a 48 volt battery? Thanks.


----------



## glyndwr1998 (Apr 27, 2013)

A leaf battery has a total capacity of 24kwh and it has 48 individual cells, so each cell is 0.5kwh. 7 cells would make a 48v battery, so would be 3.5kwh estimated.


----------



## Mark F (Aug 13, 2011)

Thanks glyndwr1998,

Isn't the Leaf voltage 360? Wouldn't that make the 48 individual cells 7.5 volts each?


----------



## Karter2 (Nov 17, 2011)

Mark F said:


> Thanks glyndwr1998,
> 
> Isn't the Leaf voltage 360? Wouldn't that make the 48 individual cells 7.5 volts each?


Yes and no !
The Leaf pack is 48 "modules" , with each module having a 2S,2P arrangement of individual cells, ..each being 15 Ahr, and 3.7 volts.
So each " module" is 7.4 volts nominal and 60 Ahr.
A series set of 7 of those modules would give a 14S, 2P, 51.8 volt nominal pack of 3.1 kWhr capacity.
If you really wanted a 48volt pack, you would need to break down one of the modules to give you a 13S, 2P , 48.1 volt nominal pack with a capacity of 2.9 kWhr.


----------



## skooler (Mar 26, 2011)

Karter2 said:


> Yes and no !
> The Leaf pack is 48 "modules" , with each module having a 2S,2P arrangement of individual cells, ..each being 15 Ahr, and 3.7 volts.
> So each " module" is 7.4 volts nominal and 60 Ahr.
> A series set of 7 of those modules would give a 14S, 2P, 51.8 volt nominal pack of 3.1 kWhr capacity.
> If you really wanted a 48volt pack, you would need to break down one of the modules to give you a 13S, 2P , 48.1 volt nominal pack with a capacity of 2.9 kWhr.


 Not quite....

Each cell is about 33AH (not 15AH) capacity and ~3.7v. 

So two parallel for 66AH @ 3.7v then two in series for ~66AH and 7.4v


----------



## glyndwr1998 (Apr 27, 2013)

With the leaf cells that I have, 3.7v is nearly empty. I run with the parameters of full charge 4.1v and end discharge 3.6v.

Hope this helps.


----------



## Mark F (Aug 13, 2011)

So given Skooler's numbers if the entire Leaf battery pack was broken down into a single 48 volt pack, the result would be a 462ah @48 volt pack?


----------



## skooler (Mar 26, 2011)

462ah x 48v is 22176wh (22kwh) which is a tad short (leaf pack is 24kwh) but more or less yes


----------



## Castiron (Dec 16, 2015)

Karter2 said:


> Yes and no !
> The Leaf pack is 48 "modules" , with each module having a 2S,2P arrangement of individual cells, ..each being 15 Ahr, and 3.7 volts.
> So each " module" is 7.4 volts nominal and 60 Ahr.
> A series set of 7 of those modules would give a 14S, 2P, 51.8 volt nominal pack of 3.1 kWhr capacity.
> *If you really wanted a 48volt pack, you would need to break down one of the modules to give you a 13S, 2P , 48.1 volt nominal pack *with a capacity of 2.9 kWhr.


I'm about to start a couple 48 v, projects and wondering how easy it is to break down the one module to accomplish this?

Thanks


----------



## dougingraham (Jul 26, 2011)

Castiron said:


> I'm about to start a couple 48 v, projects and wondering how easy it is to break down the one module to accomplish this?


I wouldn't break down a module. this is messy and would leave you with an ugly kludge. Totally topped out a module would be 8.4 volts. And completely empty it would be 6.0 volts. Nominal is 7.4 volts. If you do a 6S the full charge resting voltage is going to be 50.4 volts but nominal is going to be 44.4 volts. If you do a 7S then the full charge voltage will be 58.8 volts and the nominal voltage is going to be 51.8 volts. Do either a 6S or a 7S of the modules. If you really really need a half module I would just use the center tap of the module instead of the end on one cell. Accept a small weight penalty. Your full charge voltage for a 6.5 module setup would be 54.6 and the nominal voltage would be 48.1 volts. But what does the nominal voltage have to do with anything?

If you consider that the idea of the 48 volts comes from the lead acid world then that number is a little squishy. A fully charged "48 volt" lead acid battery is actually 57.6 volts.  The float voltage that is typically used in the telco world is 53.4 volts. The 2 volts per cell is a nominal value. Generally considered dead at 42 volts.

Is the 48 volts a regulatory limitation or a technical limitation? If technical then choose the 7S and undercharge if necessary to meet the technical number. (By technical I mean a limitation of a controller or charger.) If a regulatory limitation then the 6S Leaf modules should meet the regulatory specs and will certainly be a better in a number of ways than the lead acid equivalent would have been.


----------



## Castiron (Dec 16, 2015)

This is a golf cart and the controller max is 48v, and as I understand it from the controller manuf. it has a shutoff if the voltage is to high. They also seemed to be concerned that the components couldn't take it at continuous high voltage.

I thought about limiting the charger, but have been told that that is bad for the pack.

A little more detail. I will be running a 120ah pack so it will be 14 modules, so that's what I was thinking that if I used 13 modules and changed the odd one to be 2p instead of 2s.


----------



## skooler (Mar 26, 2011)

What controller is it? Cutoff is likely closer to 60v


----------



## Castiron (Dec 16, 2015)

skooler said:


> What controller is it? Cutoff is likely closer to 60v


According to technichian at fsip its not. fs42L500NNVS
The other one I'm doing is an alltrax which I had been told the same.


----------



## skooler (Mar 26, 2011)

They are normally higher to allow it to work with fully charged 12v lead acid which could be anything up to ~14.4v.

Also, 'life voltage' is 60vdc so makes a nice cutoff before getting into doubleb, insulation, orange cables etc.


----------



## dougingraham (Jul 26, 2011)

Castiron said:


> This is a golf cart and the controller max is 48v, and as I understand it from the controller manuf. it has a shutoff if the voltage is to high. They also seemed to be concerned that the components couldn't take it at continuous high voltage.


Ok so basically the original lead acid batteries are four 12 volt batteries, six 8 volt batteries, or eight 6 volt batteries. This means that the fresh off the charger max voltage is going to be 57.6 and the controller in the cart can handle that at a minimum. 



Castiron said:


> I thought about limiting the charger, but have been told that that is bad for the pack.


Not sure who told you this but I would not trust what they say in the future. Undercharging is what all the OEM's do in order to increase the life of the cells. Undercharging is bad for lead acid type batteries and what someone knows for their care and feeding does not apply to any of the lithium types.



Castiron said:


> A little more detail. I will be running a 120ah pack so it will be 14 modules, so that's what I was thinking that if I used 13 modules and changed the odd one to be 2p instead of 2s.


Your plan is to parallel Leaf Modules in order to obtain 120 ah. This is a reasonable plan. Per my previous note I would still go with 7S2P modules. The 7S voltage is going to be 58.8 max if you use a lithium charger. I would recommend doing this. If you can't stand the thought of going over the 57.6 volts the lead acid charger probably did then you will under charge these leaf cells to 4.11 volts per cell which would give you about an 85% capacity charge and a good long life.

If the golf cart still operates why not put a volt meter across the batteries and watch it charge. You will quickly see that the voltage approaches 60 volts near the end of charge.

It is not a good idea to just replace the batteries with Lithium. You really need to replace completely the charger with one configured for Lithium type cells.

And I am not sure you understood me in my previous note. The Leaf modules have 4 cells inside. It is a 2S2P arrangement internally. They bring out three connections to the cells inside. The middle connection goes to the center tap of the cells. If you really want to only use half of a module then connect to the center tap on the paralleled modules on one end of the string or the other. But don't dismantle the modules. If you had 120 AH golf cart batteries before you will find that this arrangement of 120 AH will weigh about 1/4 as much as the lead did and take up 1/3 the space. You could easily go to a 3P or 4P arrangement giving 180 or 240 AH and still have lots of extra space.


----------



## Castiron (Dec 16, 2015)

Yes, I have 8- 6V Deka GC45's. This is a hunting buggy (o4 Club Car DS IQ) and I wanted max range.
Yes I have a voltmeter attached and have seen the charging voltage get up in that neighborhood. It won't do it anymore as the batteries are all but shot now. But even new I don't recall the resting voltage, even freshly charged being quite that high.

I realized under charging to a degree was ok but got the impression that bringing it down to much was not good. So that is good to know.

Yes I will be getting a charger especially for the lithiums. Kinda wanting to avoid the bms though. However I would like to do some type of fuel gauge or something to alert me before getting to low on the soc.

Yes I followed you on the cells, that's why I was contemplating dividing one.
But, Hey If it will handle more voltage that would suit me just fine. I just didn't care to fry a $500 controller. (or two for that matter as I am doing a hunting buddies also)

Heck ya, I am tickled pink about shedding 500 lbs off this thing current pack is 8 batteries at 80 lbs totaling 640, new pack at 140#, they don't make a smiley big enough to post on here. Not to mention no more acid.


----------



## dougingraham (Jul 26, 2011)

Castiron said:


> Yes I followed you on the cells, that's why I was contemplating dividing one.
> But, Hey If it will handle more voltage that would suit me just fine. I just didn't care to fry a $500 controller. (or two for that matter as I am doing a hunting buddies also)


I understand your reasoning and of course there is no way I can guarantee that you won't blow up a controller with a 7S pack of Leaf cells, I would consider it highly unlikely.

Good luck with your upgrade.


----------



## Bassman (Oct 11, 2015)

I have considered doing the same thing with my golf cart. Everything I've read suggests to me that any of the controllers will take up to 60v which is very close to a fully charged lead pack.
The one thing holding me back is finding an appropriate charger that will do 10 to 15 amps and not cost a fortune. All the cheaper ones I found only charge at 2 to 3 amps.


----------



## skooler (Mar 26, 2011)

Bassman said:


> I have considered doing the same thing with my golf cart. Everything I've read suggests to me that any of the controllers will take up to 60v which is very close to a fully charged lead pack.
> The one thing holding me back is finding an appropriate charger that will do 10 to 15 amps and not cost a fortune. All the cheaper ones I found only charge at 2 to 3 amps.


Search for TC charger


----------



## Castiron (Dec 16, 2015)

sportcoupe used a QC charger for his set up and they programmed it for the lithium and voltages he wanted.


----------



## Sunking (Aug 10, 2009)

Castiron I have worked in Telecom and power generation professionally for 35 years. More importantly to you is I have built 3 golf carts. Started with Pb batteries, series DC motors, and Altrax controllers. Today would never use any of that. Today operate at 96 volts, AC motor/controller, and LFP batteries. 

Your first concern about voltage should be a non issue. Depends on which model controller you have. Any controller made for 24 to 48 volt Pb batteries is 60 volts for Equalize charging. 72 volt models can go to 90 volts. The real killer for Altrax controllers is heat generated from abuse like going up steep hills with a load demanding full power or maximum current. They maybe rated for 500 amps, but they cannot do 500 amps continuously, only burst for acceleration. Resting voltage on a 48 volt PB battery varies a bit depending on manufacture and battery alloy used. As a general rules is 50 to 50.4 volts. Right from Altrax specs any model for 48 volts can easily handle 60 volts

Undervoltage cutback: adjustable, 16-30 VDC
*30-60 VDC (48V models) (60VDC MAX)*
60-90 VDC (72V models) (90VDC MAX)
Operating Frequency: 18kHz
Control voltage range for Key Switch (KSI), Throttle and Reverse inputs: 
24-48 VDC Nom, (48V models) 60 VDC Max
24-72 VDC Nom, (72V models) 90 VDC Max

I do not use a BMS or Vampire Boards. I Bottom Balance as to eliminate any chance of an over discharge, and I only charge to about 90% SOC. My controller has some features you do not have like a Coulomb Counter I use as a Fuel Gauge. Voltage does not tell you a whole lot about SOC. In fact fairly meaningless. When the batteries are at rest and have been rested a while the voltage gives you a Ball Park idea.

The Biggest threat to your battery is Over Discharge. For me that is not an issue. I have two layers of defense. First lin eof defense is the Controller LVC circuit. It can be triggered in one of two ways. Either from an external source like a BMS which I do not use, or a Voltage Set Point. Mine is set to operate if the pack voltage drops to or goes lower than 96 volts for 30 seconds. That is well above the danger zone of 90 volts. At 96 volts on my pack is roughly 10 to 20% capacity left. 

Second line of defense is I Bottom Balance. With a Bottom Balanced pack makes it almost impossible to over discharge a Lithium battery because no cell has the energy left in it to drive adjacent cells in series into reverse polarity. You do not have that option available to you because the LEAF MODULES are 2S. You cannot BB a 2S battery because you have to be able to put all of them in parallel to BB in 1SXP configuration. 

You do get some weight gain advantages using Lithium, but I am not sure you get what you are claiming. Maybe but you have to compare capacity Apples to Apples. Capacity is not measured in AH when comparing. 1 AH of lithium does not equal 1 AH of a Pb battery. To arrive at equal capacity in Watt Hours, do not use Amp Hours, is a ratio of what I call rule 69. It takes 69 Watt Hours of Lithium to equal 100 wh of Pb, or 70%. There are two reasons. 1 a Pb only 50% of the capacity is usable in a Pb battery vs 80% in a Lithium. 2. Peukert Law affects Pb more than then Lithium. 

Today's 48 volt factory golf carts, at least from EZGO use Trojan 8 volt 160 AH Ranger battery, the best Pb for carts today. Total capacity at currents golf carts use is 1.8 Kwh per battery and using 6 of them works out to 10.8 Kwh weighing in at 456 pounds. A LFP equivalent would be a 16S 110 AH pack. Using CALB 100 AH cells would weigh in at around 120 pounds or a 330 pound weight reduction.

Next do not expect to gain much in the way of speed. It will be quicker (acceleration) bu tnot much in the way of speed. Maybe 3 to 5 mph tops faster. You get more torque, but not more RPM's. The slight increase in speed you get is from the battery lower internal resistance. Torques is from current which the controller can provide. RPM is from Voltage on a DC motror and you are not increasing voltage very much. 

My current cart runs 60 mph, and can go faster if I raise the max RPM limit set in the controller. Only way you can get more speed assuming you stay with 48 volts is either change the wheel/tire size, or change the differential axle gear ratio. Down side is if you do that you loose Torque and prone to over heating the controller.


----------



## skooler (Mar 26, 2011)

Sunking said:


> Castiron I have worked in Telecom and power generation professionally for 35 years. More importantly to you is I have built 3 golf carts. Started with Pb batteries, series DC motors, and Altrax controllers. Today would never use any of that. Today operate at 96 volts, AC motor/controller, and LFP batteries.
> 
> Your first concern about voltage should be a non issue. Depends on which model controller you have. Any controller made for 24 to 48 volt Pb batteries is 60 volts for Equalize charging. 72 volt models can go to 90 volts. The real killer for Altrax controllers is heat generated from abuse like going up steep hills with a load demanding full power or maximum current. They maybe rated for 500 amps, but they cannot do 500 amps continuously, only burst for acceleration. Resting voltage on a 48 volt PB battery varies a bit depending on manufacture and battery alloy used. As a general rules is 50 to 50.4 volts.
> 
> ...


Excellent post Sunking. Good advice, please take it!


----------



## Castiron (Dec 16, 2015)

Sunking, thanks for the info.

I have the leaf cells, so there won't be any changing to another type. From what I have read, 14 cells 120ah pack should be more than enough to satisfy my needs.

While I see what your saying about not truly being able to bottom balance, Isn't it sufficient to bottom balance ea module as I see many others here are doing?

What would be a simple method to prevent over discharge?

Speed increase isn't real important 20-25mph is sufficient. Much of the time will be spent easing along at a couple mph anyway. My tires are already 25" so I won't be increasing them anymore.

As I mentioned earlier I currently have 8- 6V batteries weighing 80#'s ea. so I will be shedding 500#'s less the onboard charger, which I was going to go to when current charger died anyway.


----------



## Sunking (Aug 10, 2009)

Castiron said:


> I have the leaf cells, so there won't be any changing to another type. From what I have read, 14 cells 120ah pack should be more than enough to satisfy my needs.


I never said it would not, and yes it should work great. 



Castiron said:


> While I see what your saying about not truly being able to bottom balance, Isn't it sufficient to bottom balance ea module as I see many others here are doing?


I do not think you can if I understand correctly. To Bottom Ballance you must put all cells in parallel is 1SxP configuration. A Leaf module is 2S right? 



Castiron said:


> What would be a simple method to prevent over discharge?


 You have to use a LVC circuit of some sort. I do not think Altrax has that built in. There are two ways to go about it. 

1. In a BB pack you simply disconnect when the pack voltage reaches a set point. Around 10 to 20% SOC. Not certain what voltage Leaf cells ned cut-off at . I think never go below 3 volts and I believe others have said 3.3 to 3.5 volts per cell for disconnect. So 14S would be around 46.2 to 49 volts. 

2. In a Top Balanced battery using a Cell Monitor BMS, you disconnect when any one cell voltage reaches a defined set point like 3.5 volts on a Leaf battery.

I maybe mistaken about the Leaf battery, but I have never heard of anyone BB them. Now what I will say commercial EV manufactures like Nissan use matched cells. By that I mean each cell capacity is within 1 %, so really makes no difference if the pack is Top or Bottom Balanced. 



Castiron said:


> Speed increase isn't real important 20-25mph is sufficient. Much of the time will be spent easing along at a couple mph anyway. My tires are already 25" so I won't be increasing them anymore.


Unless you change something in the differential or wheel/tire size that is highly unlikely. Basically will only go as fast as it does now. It will just accelerate quicker Golf carts by design and law are made to not exceed 19 mph with 14 being typical. To do that the manufactures use wheel/tire size, differential ration, and motor RPM to limit speed. I assume your cart uses a Series Motor. Voltage and motor RPM are directly related to each other. You are not increasing the voltage, thus not turning higher RPM on the motor. That is why I said unless you change something like tire/wheel size (larger) or a lower gear ration in the differential, your speed will not change much. It will just accelerate quicker due to the higher current the new controller provides. You will get maybe 2 to 3 mph faster because the voltage losses will be a little lower with a Lithium battery and less weight.


----------



## skooler (Mar 26, 2011)

favguy said:


> Just to clarify, you can balance, (bottom or top) individual leaf module cells as the module also has a centre terminal for this


Yes but you cant put each individual cell in parallel as you would (should) with individual cells. What you can do the is have two parallel runs which is probably good enough if you can get the voltages to match. 

Remember that these modules are 'handed which adds more confusion!


----------



## favguy (May 2, 2008)

I realised this about 2 minutes after posting, hence immediately deleted the post!! How did you get to see it lol??!!


----------



## Castiron (Dec 16, 2015)

Sunking said:


> 1. In a BB pack you simply disconnect when the pack voltage reaches a set point. Around 10 to 20% SOC. Not certain what voltage Leaf cells ned cut-off at . I think never go below 3 volts and I believe others have said 3.3 to 3.5 volts per cell for disconnect. So 14S would be around 46.2 to 49 volts.
> 
> 2. In a Top Balanced battery using a Cell Monitor BMS, you disconnect when any one cell voltage reaches a defined set point like 3.5 volts on a Leaf battery.
> 
> ...


What is a BB pack?

My buggy is an IQ (sepex). The alltrax is programmable and I think it does have an lvc. However the other cart I'm doing is not.


----------



## Castiron (Dec 16, 2015)

skooler said:


> Remember that these modules are 'handed which adds more confusion!


How are they handed?


----------



## Sunking (Aug 10, 2009)

Castiron said:


> What is a BB pack?


 Bottom Balanced. 



Castiron said:


> My buggy is an IQ (sepex). The alltrax is programmable and I think it does have an lvc.


I assume AXE Models? I had to go look and yes they do have LVC so you are set if you want to just use pack voltage rather than cell voltage. Only thing I am not sure of is if you can set thee voltage high enough of around 46 to 48 volts. You do not want to mess around falling off the cliff of over discharge. You want to leave around 10 to 20% SOC left in the batteries.


----------



## Castiron (Dec 16, 2015)

Sunking said:


> Bottom Balanced.
> 
> I assume AXE Models? I had to go look and yes they do have LVC so you are set if you want to just use pack voltage rather than cell voltage. Only thing I am not sure of is if you can set thee voltage high enough of around 46 to 48 volts. You do not want to mess around falling off the cliff of over discharge. You want to leave around 10 to 20% SOC left in the batteries.


I bought it several yrs ago from D&D and they rebadged it as I recall but it is alltrax and programmable. But I bet your right about the lvc not being able to be set high enough.

So back to my prev. question. What would you recommend for an lvc?


----------



## Sunking (Aug 10, 2009)

I cannot say for sure the Alltrax cannot be set high enough. Best bet is to call them and ask. 

If not you will have to an external circuit. They can be purchased, but not so complicated you cannot make one. Nothing more than a Voltage Comparature circuit and a Contactor.


----------



## lawn cart (Aug 9, 2013)

I have 5 leaf modules in an electric riding mower. I guess I am easily confused but am having trouble figuring out when I should charge the pack. Right now it is down to 38.5 volts with each module at 7.7 volts. Would charging it when it gets down to 30 volts be a reasonable way to extend the battery life??


----------



## glyndwr1998 (Apr 27, 2013)

Hi,
I believe a leaf cell is considered low on charge at around 7v. There is not a lot of energy left in the cell and the voltage drops quite quickly below this point.
Have a search in the forum or google for a discharge curve for a leaf cell, you will see the sharp drop in th curve around the 3.5v area.
They can be taken as low as 3v (that's 6v for a leaf cell) but they won't last you as long this way.
Anthony


----------



## favguy (May 2, 2008)

Hi,
For long life use, charge when voltage drops to 7.3v per module (3.65v per cell). This is about 15% state of charge. 

7v is 10% state of charge and I'd consider this the lowest safe place to be for long battery life.

As already said, 6v is really low and literally moments of use away from a totally flat battery, shortened life, and potential immediate damage.

Have a look at this page:

http://hybridautocenter.com/HAC4/index.php?option=com_content&view=article&id=72&Itemid=631


----------



## lawn cart (Aug 9, 2013)

Of course you are right. Not sure what I was thinking. It will be interesting to see how long these run before they are ready to charge. I am not trying to mow, just driving around the property. Also, this REcharge mower has a bar graph voltage meter and it is still on the top bar. It is set for 3 12 volt lead acid batteries so I am not sure it will ever drop. WE shall see.


----------



## Castiron (Dec 16, 2015)

Sunking said:


> If not you will have to an external circuit. They can be purchased, but not so complicated you cannot make one. Nothing more than a Voltage Comparature circuit and a Contactor.


What would it take to make an LVC for 48v?

Also you mentioned handing of the batteries earlier, what is that and do I need to be concerned with it.


----------



## skooler (Mar 26, 2011)




----------



## Castiron (Dec 16, 2015)

Gotcha, just a physical trait. I hadn't looked that close at them.


----------

