Topics

Battery upgrade

Ron Frost
 

I am in need of a small, physical size, 6 volt battery for my Crosley driven homemade farm tractor. Where might I find one.
Also, I understand that there is a 12 volt generator replacement system available. Could someone enlighten me on this. 
Thanks
Ron Frost
Kersey, PA
 

crosleyshortsport
 

You can get a Napa gold 6 volt battery. They are the best. Use a trickle charger in the winter to keep it good. Why change to 12 volt? The 6 volt positive ground system works fine. 

On Jan 10, 2018 6:00 PM, "rd.frost via Groups.Io" <rd.frost=yahoo.com@groups.io> wrote:
I am in need of a small, physical size, 6 volt battery for my Crosley driven homemade farm tractor. Where might I find one.
Also, I understand that there is a 12 volt generator replacement system available. Could someone enlighten me on this. 
Thanks
Ron Frost
Kersey, PA
 

Bob Hickman
 


My experience shows me that the 6 volt battery is strong enouth to turn a Crosley engine over quite fast, and if the engine is properly tuned, the 6 volt battery should do the job just fine.

Bob Hickman

----- Original Message -----
Sent: Wednesday, January 10, 2018 5:38 PM
Subject: Re: [Crosley-Gang] Battery upgrade

You can get a Napa gold 6 volt battery. They are the best. Use a trickle charger in the winter to keep it good. Why change to 12 volt? The 6 volt positive ground system works fine. 

On Jan 10, 2018 6:00 PM, "rd.frost via Groups.Io" <rd.frost=yahoo.com@groups.io> wrote:
I am in need of a small, physical size, 6 volt battery for my Crosley driven homemade farm tractor. Where might I find one.
Also, I understand that there is a 12 volt generator replacement system available. Could someone enlighten me on this. 
Thanks
Ron Frost
Kersey, PA
 

Jim Bollman
 

Ron, it appears those that answered didn't catch that the battery needed to be small to fit in a homemade tractor. I had a similar problem back a few years. I initially found some wet NiCad cells that you bolt together with straps to make  battery the shape and voltage you want. I bought them used, they were surplus from some aviation application and worked for a few years and when one of the cells died I couldn't find a replacement at a reasonable price. I had a mag on my tractor so I ended up just using a jumper battery.

I  planned to go with rechargeable Lithium Ion cells. I was going to build a battery pack the size I needed out of 18650 batteries. They are 3.7 volts, so I was going to use two banks of parallel batteries hooked in series to give me 7.4 volts. If I remember correctly (don't own the tractor anymore, I was going to end up with 8 cells total connected 4X2. Now that would give around 48 amps at 7.4 volts, if I used the high capacity cells and half that for the cheaper ones, back then the cells were very expensive, now under $20 for 8 high capacity cells. The more cells you can stack in your space the more current. My tractor didn't have a generator so I was going to build/modify a small charger and just plug it in to recharge. That doesn't sound like a lot of amps but the discharge rate that Lithium batteries have it would give a lot higher cranking amps, just not for a long time. This was before the Lithium jumper batteries they sell now, I think they use the same batteries inside and they claim 500 amp cranking and they do it a package that only has around 20 amps and they will crank a V8. I have not built one of these so it is all theory at this point. Just be sure to use heavy gauge and short wire, since you will be pulling a lot of amps and light weight wire and long runs will drop your voltage fast.

John Van Sickle
 

Yes -The NAPA is an excellent choice-You can also check with Interstate -which make the NAPA battery.

I have been using them for years with great success.

PATRICIA GRITTI
 

Hi Jim
Your theory about Li ion cells stirred my "head scratching" gene. According to Amazon advertisements 18650 cells seem to have capacity of up to 3,500 mAH. Don't understand how four 18650 cells in series could produce enough amperage to crank a 6 volt starter. Hope someone seeing my concern will be kind enough to explain.
Don

On January 11, 2018 at 8:18 AM Jim Bollman <Jim@...> wrote:

Ron, it appears those that answered didn't catch that the battery needed to be small to fit in a homemade tractor. I had a similar problem back a few years. I initially found some wet NiCad cells that you bolt together with straps to make  battery the shape and voltage you want. I bought them used, they were surplus from some aviation application and worked for a few years and when one of the cells died I couldn't find a replacement at a reasonable price. I had a mag on my tractor so I ended up just using a jumper battery.

I  planned to go with rechargeable Lithium Ion cells. I was going to build a battery pack the size I needed out of 18650 batteries. They are 3.7 volts, so I was going to use two banks of parallel batteries hooked in series to give me 7.4 volts. If I remember correctly (don't own the tractor anymore, I was going to end up with 8 cells total connected 4X2. Now that would give around 48 amps at 7.4 volts, if I used the high capacity cells and half that for the cheaper ones, back then the cells were very expensive, now under $20 for 8 high capacity cells. The more cells you can stack in your space the more current. My tractor didn't have a generator so I was going to build/modify a small charger and just plug it in to recharge. That doesn't sound like a lot of amps but the discharge rate that Lithium batteries have it would give a lot higher cranking amps, just not for a long time. This was before the Lithium jumper batteries they sell now, I think they use the same batteries inside and they claim 500 amp cranking and they do it a package that only has around 20 amps and they will crank a V8. I have not built one of these so it is all theory at this point. Just be sure to use heavy gauge and short wire, since you will be pulling a lot of amps and light weight wire and long runs will drop your voltage fast.

Jim Bollman
 

It is the difference between total AH of capacity and how fast you can pull the current out. To make simple math lets say the battery will produce 10AH that is 10 amps for an hour. A lithium battery can produce high amperage for a short time. Lets say you need 100 amps to run your starter, in theory a lithium could supply 100 amps for 6 minutes. So the approach isn't good if your engine starts hard and requires a lot of cracking to start.

Batteries in series increase the voltage but does not increase the current. Batteries in parallel increase the current but not the voltage. To get 48amps I put four 12000mAH batteries in parallel, that would be at 3.7V, then two of these bank in series gives us 7.4 volts at 45 AH.  if we used four 3500mAH in parallel that gives us 14 AH and if we put two of those banks together we get 7.4 volts of 14AH cranking. Here is a link to the 12AH Lithiums. https://www.walmart.com/ip/4pcs-18650-3-7V-12000mAh-Rechargeable-Li-ion-Battery-US-Plug-Charger-New-On-Clearance/461118391 Now that I look at other sources, Walmart may be using creative rating on their batteries and even though it says 12000mAH on the battery it may be the 4 batteries at each 3000mAH. The batteries are very small (~2.6" long and ~.6" in dia), so you can stack a lot of them in a small space, you may need more than 8 but that is what I would start with, if I was doing the experiment. On a different web site I see a number of 20amps being able to be pulled out of each 3000,AH battery so with 4x2 you would get 80amps to the starter, if you did a 5X2 you would get 100amps, 6x2 120 amps, etc.  A 4x2 configuration of 3000mAH batteries should be capable of doing 80amps for about 9 minutes if I did the math right. With the usual problems of battery specs I would count on a lot less than that but if your Crosley engine doesn't start in less than a minutes of cranking you probably should hook up a bigger battery while your are fixing thee problem. I don't really know how much a Crosley starter pulls so that may be a good place to start.

Hope I didn't make it more confusing. If I did, when I get a little more time I will draw up a diagram and do a little more digging for what other have done.

Jim...

On Jan 11, 2018, at 9:58 AM, PATRICIA GRITTI <donald-gritti@...> wrote:

Hi Jim
Your theory about Li ion cells stirred my "head scratching" gene. According to Amazon advertisements 18650 cells seem to have capacity of up to 3,500 mAH. Don't understand how four 18650 cells in series could produce enough amperage to crank a 6 volt starter. Hope someone seeing my concern will be kind enough to explain.
Don

On January 11, 2018 at 8:18 AM Jim Bollman <Jim@...> wrote:

Ron, it appears those that answered didn't catch that the battery needed to be small to fit in a homemade tractor. I had a similar problem back a few years. I initially found some wet NiCad cells that you bolt together with straps to make  battery the shape and voltage you want. I bought them used, they were surplus from some aviation application and worked for a few years and when one of the cells died I couldn't find a replacement at a reasonable price. I had a mag on my tractor so I ended up just using a jumper battery.

I  planned to go with rechargeable Lithium Ion cells. I was going to build a battery pack the size I needed out of 18650 batteries. They are 3.7 volts, so I was going to use two banks of parallel batteries hooked in series to give me 7.4 volts. If I remember correctly (don't own the tractor anymore, I was going to end up with 8 cells total connected 4X2. Now that would give around 48 amps at 7.4 volts, if I used the high capacity cells and half that for the cheaper ones, back then the cells were very expensive, now under $20 for 8 high capacity cells. The more cells you can stack in your space the more current. My tractor didn't have a generator so I was going to build/modify a small charger and just plug it in to recharge. That doesn't sound like a lot of amps but the discharge rate that Lithium batteries have it would give a lot higher cranking amps, just not for a long time. This was before the Lithium jumper batteries they sell now, I think they use the same batteries inside and they claim 500 amp cranking and they do it a package that only has around 20 amps and they will crank a V8. I have not built one of these so it is all theory at this point. Just be sure to use heavy gauge and short wire, since you will be pulling a lot of amps and light weight wire and long runs will drop your voltage fast.

 

Bill Cunningham
 

Good job Jim!   You are a Master of I = E/R!    Georg Simon Ohm would be proud!




From: Crosley-Gang@groups.io <Crosley-Gang@groups.io> on behalf of Jim Bollman <Jim@...>
Sent: Thursday, January 11, 2018 9:46 AM
To: Crosley-Gang@groups.io
Subject: Re: [Crosley-Gang] Battery upgrade
 
It is the difference between total AH of capacity and how fast you can pull the current out. To make simple math lets say the battery will produce 10AH that is 10 amps for an hour. A lithium battery can produce high amperage for a short time. Lets say you need 100 amps to run your starter, in theory a lithium could supply 100 amps for 6 minutes. So the approach isn't good if your engine starts hard and requires a lot of cracking to start.

Batteries in series increase the voltage but does not increase the current. Batteries in parallel increase the current but not the voltage. To get 48amps I put four 12000mAH batteries in parallel, that would be at 3.7V, then two of these bank in series gives us 7.4 volts at 45 AH.  if we used four 3500mAH in parallel that gives us 14 AH and if we put two of those banks together we get 7.4 volts of 14AH cranking. Here is a link to the 12AH Lithiums. https://www.walmart.com/ip/4pcs-18650-3-7V-12000mAh-Rechargeable-Li-ion-Battery-US-Plug-Charger-New-On-Clearance/461118391 Now that I look at other sources, Walmart may be using creative rating on their batteries and even though it says 12000mAH on the battery it may be the 4 batteries at each 3000mAH. The batteries are very small (~2.6" long and ~.6" in dia), so you can stack a lot of them in a small space, you may need more than 8 but that is what I would start with, if I was doing the experiment. On a different web site I see a number of 20amps being able to be pulled out of each 3000,AH battery so with 4x2 you would get 80amps to the starter, if you did a 5X2 you would get 100amps, 6x2 120 amps, etc.  A 4x2 configuration of 3000mAH batteries should be capable of doing 80amps for about 9 minutes if I did the math right. With the usual problems of battery specs I would count on a lot less than that but if your Crosley engine doesn't start in less than a minutes of cranking you probably should hook up a bigger battery while your are fixing thee problem. I don't really know how much a Crosley starter pulls so that may be a good place to start.

Hope I didn't make it more confusing. If I did, when I get a little more time I will draw up a diagram and do a little more digging for what other have done.

Jim...

On Jan 11, 2018, at 9:58 AM, PATRICIA GRITTI <donald-gritti@...> wrote:

Hi Jim
Your theory about Li ion cells stirred my "head scratching" gene. According to Amazon advertisements 18650 cells seem to have capacity of up to 3,500 mAH. Don't understand how four 18650 cells in series could produce enough amperage to crank a 6 volt starter. Hope someone seeing my concern will be kind enough to explain.
Don

On January 11, 2018 at 8:18 AM Jim Bollman <Jim@...> wrote:

Ron, it appears those that answered didn't catch that the battery needed to be small to fit in a homemade tractor. I had a similar problem back a few years. I initially found some wet NiCad cells that you bolt together with straps to make  battery the shape and voltage you want. I bought them used, they were surplus from some aviation application and worked for a few years and when one of the cells died I couldn't find a replacement at a reasonable price. I had a mag on my tractor so I ended up just using a jumper battery.

I  planned to go with rechargeable Lithium Ion cells. I was going to build a battery pack the size I needed out of 18650 batteries. They are 3.7 volts, so I was going to use two banks of parallel batteries hooked in series to give me 7.4 volts. If I remember correctly (don't own the tractor anymore, I was going to end up with 8 cells total connected 4X2. Now that would give around 48 amps at 7.4 volts, if I used the high capacity cells and half that for the cheaper ones, back then the cells were very expensive, now under $20 for 8 high capacity cells. The more cells you can stack in your space the more current. My tractor didn't have a generator so I was going to build/modify a small charger and just plug it in to recharge. That doesn't sound like a lot of amps but the discharge rate that Lithium batteries have it would give a lot higher cranking amps, just not for a long time. This was before the Lithium jumper batteries they sell now, I think they use the same batteries inside and they claim 500 amp cranking and they do it a package that only has around 20 amps and they will crank a V8. I have not built one of these so it is all theory at this point. Just be sure to use heavy gauge and short wire, since you will be pulling a lot of amps and light weight wire and long runs will drop your voltage fast.

 

PATRICIA GRITTI
 

Thank you Jim
Good math & thank you for the WalMart lead. Looking at the WalMart website found lithium ion #RCR 123a batteries, a bit larger & reasonably priced.
Don

On January 11, 2018 at 10:46 AM Jim Bollman <Jim@...> wrote:

It is the difference between total AH of capacity and how fast you can pull the current out. To make simple math lets say the battery will produce 10AH that is 10 amps for an hour. A lithium battery can produce high amperage for a short time. Lets say you need 100 amps to run your starter, in theory a lithium could supply 100 amps for 6 minutes. So the approach isn't good if your engine starts hard and requires a lot of cracking to start.

Batteries in series increase the voltage but does not increase the current. Batteries in parallel increase the current but not the voltage. To get 48amps I put four 12000mAH batteries in parallel, that would be at 3.7V, then two of these bank in series gives us 7.4 volts at 45 AH.  if we used four 3500mAH in parallel that gives us 14 AH and if we put two of those banks together we get 7.4 volts of 14AH cranking. Here is a link to the 12AH Lithiums. https://www.walmart.com/ip/4pcs-18650-3-7V-12000mAh-Rechargeable-Li-ion-Battery-US-Plug-Charger-New-On-Clearance/461118391 Now that I look at other sources, Walmart may be using creative rating on their batteries and even though it says 12000mAH on the battery it may be the 4 batteries at each 3000mAH. The batteries are very small (~2.6" long and ~.6" in dia), so you can stack a lot of them in a small space, you may need more than 8 but that is what I would start with, if I was doing the experiment. On a different web site I see a number of 20amps being able to be pulled out of each 3000,AH battery so with 4x2 you would get 80amps to the starter, if you did a 5X2 you would get 100amps, 6x2 120 amps, etc.  A 4x2 configuration of 3000mAH batteries should be capable of doing 80amps for about 9 minutes if I did the math right. With the usual problems of battery specs I would count on a lot less than that but if your Crosley engine doesn't start in less than a minutes of cranking you probably should hook up a bigger battery while your are fixing thee problem. I don't really know how much a Crosley starter pulls so that may be a good place to start.

Hope I didn't make it more confusing. If I did, when I get a little more time I will draw up a diagram and do a little more digging for what other have done.

Jim...

On Jan 11, 2018, at 9:58 AM, PATRICIA GRITTI <donald-gritti@...> wrote:

Hi Jim
Your theory about Li ion cells stirred my "head scratching" gene. According to Amazon advertisements 18650 cells seem to have capacity of up to 3,500 mAH. Don't understand how four 18650 cells in series could produce enough amperage to crank a 6 volt starter. Hope someone seeing my concern will be kind enough to explain.
Don

On January 11, 2018 at 8:18 AM Jim Bollman <Jim@...> wrote:

Ron, it appears those that answered didn't catch that the battery needed to be small to fit in a homemade tractor. I had a similar problem back a few years. I initially found some wet NiCad cells that you bolt together with straps to make  battery the shape and voltage you want. I bought them used, they were surplus from some aviation application and worked for a few years and when one of the cells died I couldn't find a replacement at a reasonable price. I had a mag on my tractor so I ended up just using a jumper battery.

I  planned to go with rechargeable Lithium Ion cells. I was going to build a battery pack the size I needed out of 18650 batteries. They are 3.7 volts, so I was going to use two banks of parallel batteries hooked in series to give me 7.4 volts. If I remember correctly (don't own the tractor anymore, I was going to end up with 8 cells total connected 4X2. Now that would give around 48 amps at 7.4 volts, if I used the high capacity cells and half that for the cheaper ones, back then the cells were very expensive, now under $20 for 8 high capacity cells. The more cells you can stack in your space the more current. My tractor didn't have a generator so I was going to build/modify a small charger and just plug it in to recharge. That doesn't sound like a lot of amps but the discharge rate that Lithium batteries have it would give a lot higher cranking amps, just not for a long time. This was before the Lithium jumper batteries they sell now, I think they use the same batteries inside and they claim 500 amp cranking and they do it a package that only has around 20 amps and they will crank a V8. I have not built one of these so it is all theory at this point. Just be sure to use heavy gauge and short wire, since you will be pulling a lot of amps and light weight wire and long runs will drop your voltage fast.

 

PATRICIA GRITTI
 

Words of caution; recently a neighbor had a fire that destroyed their house. It was determined that the fire was caused when lithium ion batteries were charged by a charger THAT WAS NOT DESIGNED FOR LITHIUM ION BATTERIES! If you use lithium ion batteries do not recharge them from a normal automotive electrical system or from a charger intended for lead acid batteries.
Don

On January 11, 2018 at 10:46 AM Jim Bollman <Jim@...> wrote:

It is the difference between total AH of capacity and how fast you can pull the current out. To make simple math lets say the battery will produce 10AH that is 10 amps for an hour. A lithium battery can produce high amperage for a short time. Lets say you need 100 amps to run your starter, in theory a lithium could supply 100 amps for 6 minutes. So the approach isn't good if your engine starts hard and requires a lot of cracking to start.

Batteries in series increase the voltage but does not increase the current. Batteries in parallel increase the current but not the voltage. To get 48amps I put four 12000mAH batteries in parallel, that would be at 3.7V, then two of these bank in series gives us 7.4 volts at 45 AH.  if we used four 3500mAH in parallel that gives us 14 AH and if we put two of those banks together we get 7.4 volts of 14AH cranking. Here is a link to the 12AH Lithiums. https://www.walmart.com/ip/4pcs-18650-3-7V-12000mAh-Rechargeable-Li-ion-Battery-US-Plug-Charger-New-On-Clearance/461118391 Now that I look at other sources, Walmart may be using creative rating on their batteries and even though it says 12000mAH on the battery it may be the 4 batteries at each 3000mAH. The batteries are very small (~2.6" long and ~.6" in dia), so you can stack a lot of them in a small space, you may need more than 8 but that is what I would start with, if I was doing the experiment. On a different web site I see a number of 20amps being able to be pulled out of each 3000,AH battery so with 4x2 you would get 80amps to the starter, if you did a 5X2 you would get 100amps, 6x2 120 amps, etc.  A 4x2 configuration of 3000mAH batteries should be capable of doing 80amps for about 9 minutes if I did the math right. With the usual problems of battery specs I would count on a lot less than that but if your Crosley engine doesn't start in less than a minutes of cranking you probably should hook up a bigger battery while your are fixing thee problem. I don't really know how much a Crosley starter pulls so that may be a good place to start.

Hope I didn't make it more confusing. If I did, when I get a little more time I will draw up a diagram and do a little more digging for what other have done.

Jim...

On Jan 11, 2018, at 9:58 AM, PATRICIA GRITTI <donald-gritti@...> wrote:

Hi Jim
Your theory about Li ion cells stirred my "head scratching" gene. According to Amazon advertisements 18650 cells seem to have capacity of up to 3,500 mAH. Don't understand how four 18650 cells in series could produce enough amperage to crank a 6 volt starter. Hope someone seeing my concern will be kind enough to explain.
Don

On January 11, 2018 at 8:18 AM Jim Bollman <Jim@...> wrote:

Ron, it appears those that answered didn't catch that the battery needed to be small to fit in a homemade tractor. I had a similar problem back a few years. I initially found some wet NiCad cells that you bolt together with straps to make  battery the shape and voltage you want. I bought them used, they were surplus from some aviation application and worked for a few years and when one of the cells died I couldn't find a replacement at a reasonable price. I had a mag on my tractor so I ended up just using a jumper battery.

I  planned to go with rechargeable Lithium Ion cells. I was going to build a battery pack the size I needed out of 18650 batteries. They are 3.7 volts, so I was going to use two banks of parallel batteries hooked in series to give me 7.4 volts. If I remember correctly (don't own the tractor anymore, I was going to end up with 8 cells total connected 4X2. Now that would give around 48 amps at 7.4 volts, if I used the high capacity cells and half that for the cheaper ones, back then the cells were very expensive, now under $20 for 8 high capacity cells. The more cells you can stack in your space the more current. My tractor didn't have a generator so I was going to build/modify a small charger and just plug it in to recharge. That doesn't sound like a lot of amps but the discharge rate that Lithium batteries have it would give a lot higher cranking amps, just not for a long time. This was before the Lithium jumper batteries they sell now, I think they use the same batteries inside and they claim 500 amp cranking and they do it a package that only has around 20 amps and they will crank a V8. I have not built one of these so it is all theory at this point. Just be sure to use heavy gauge and short wire, since you will be pulling a lot of amps and light weight wire and long runs will drop your voltage fast.

 


 

L.E. Hardee
 

Some emergency lights use 6 volt batteries that are similar in size to small lawn mower batteries.  I do not know the amp hour ratings. 

On Thu, Jan 11, 2018 at 11:43 AM, PATRICIA GRITTI <donald-gritti@...> wrote:
Words of caution; recently a neighbor had a fire that destroyed their house. It was determined that the fire was caused when lithium ion batteries were charged by a charger THAT WAS NOT DESIGNED FOR LITHIUM ION BATTERIES! If you use lithium ion batteries do not recharge them from a normal automotive electrical system or from a charger intended for lead acid batteries.
Don

On January 11, 2018 at 10:46 AM Jim Bollman <Jim@...> wrote:

It is the difference between total AH of capacity and how fast you can pull the current out. To make simple math lets say the battery will produce 10AH that is 10 amps for an hour. A lithium battery can produce high amperage for a short time. Lets say you need 100 amps to run your starter, in theory a lithium could supply 100 amps for 6 minutes. So the approach isn't good if your engine starts hard and requires a lot of cracking to start.

Batteries in series increase the voltage but does not increase the current. Batteries in parallel increase the current but not the voltage. To get 48amps I put four 12000mAH batteries in parallel, that would be at 3.7V, then two of these bank in series gives us 7.4 volts at 45 AH.  if we used four 3500mAH in parallel that gives us 14 AH and if we put two of those banks together we get 7.4 volts of 14AH cranking. Here is a link to the 12AH Lithiums. https://www.walmart.com/ip/4pcs-18650-3-7V-12000mAh-Rechargeable-Li-ion-Battery-US-Plug-Charger-New-On-Clearance/461118391 Now that I look at other sources, Walmart may be using creative rating on their batteries and even though it says 12000mAH on the battery it may be the 4 batteries at each 3000mAH. The batteries are very small (~2.6" long and ~.6" in dia), so you can stack a lot of them in a small space, you may need more than 8 but that is what I would start with, if I was doing the experiment. On a different web site I see a number of 20amps being able to be pulled out of each 3000,AH battery so with 4x2 you would get 80amps to the starter, if you did a 5X2 you would get 100amps, 6x2 120 amps, etc.  A 4x2 configuration of 3000mAH batteries should be capable of doing 80amps for about 9 minutes if I did the math right. With the usual problems of battery specs I would count on a lot less than that but if your Crosley engine doesn't start in less than a minutes of cranking you probably should hook up a bigger battery while your are fixing thee problem. I don't really know how much a Crosley starter pulls so that may be a good place to start.

Hope I didn't make it more confusing. If I did, when I get a little more time I will draw up a diagram and do a little more digging for what other have done.

Jim...

On Jan 11, 2018, at 9:58 AM, PATRICIA GRITTI <donald-gritti@...> wrote:

Hi Jim
Your theory about Li ion cells stirred my "head scratching" gene. According to Amazon advertisements 18650 cells seem to have capacity of up to 3,500 mAH. Don't understand how four 18650 cells in series could produce enough amperage to crank a 6 volt starter. Hope someone seeing my concern will be kind enough to explain.
Don

On January 11, 2018 at 8:18 AM Jim Bollman <Jim@...> wrote:

Ron, it appears those that answered didn't catch that the battery needed to be small to fit in a homemade tractor. I had a similar problem back a few years. I initially found some wet NiCad cells that you bolt together with straps to make  battery the shape and voltage you want. I bought them used, they were surplus from some aviation application and worked for a few years and when one of the cells died I couldn't find a replacement at a reasonable price. I had a mag on my tractor so I ended up just using a jumper battery.

I  planned to go with rechargeable Lithium Ion cells. I was going to build a battery pack the size I needed out of 18650 batteries. They are 3.7 volts, so I was going to use two banks of parallel batteries hooked in series to give me 7.4 volts. If I remember correctly (don't own the tractor anymore, I was going to end up with 8 cells total connected 4X2. Now that would give around 48 amps at 7.4 volts, if I used the high capacity cells and half that for the cheaper ones, back then the cells were very expensive, now under $20 for 8 high capacity cells. The more cells you can stack in your space the more current. My tractor didn't have a generator so I was going to build/modify a small charger and just plug it in to recharge. That doesn't sound like a lot of amps but the discharge rate that Lithium batteries have it would give a lot higher cranking amps, just not for a long time. This was before the Lithium jumper batteries they sell now, I think they use the same batteries inside and they claim 500 amp cranking and they do it a package that only has around 20 amps and they will crank a V8. I have not built one of these so it is all theory at this point. Just be sure to use heavy gauge and short wire, since you will be pulling a lot of amps and light weight wire and long runs will drop your voltage fast.