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18650 trolling battery solar charging
#11
(06-05-2020, 09:43 PM)floydR Wrote:
(06-05-2020, 05:25 PM)dbldrew Wrote:
(06-05-2020, 03:53 PM)OffGridInTheCity Wrote: Another one that is cheaper, fully programmable is the famous MPT-7210a  (many youtubes on this).  Its limited to 10a on output but is fully programmable - and you could do 2 in parallel if you like the 1st one.    https://www.ebay.com/itm/LCD-MPT-7210A-M...Swe9tepqNQ

if i get the MPT-7210a would there be any issue with running the 4 - 50W panels that could produce more amps then the output of the controller? Or is it just not getting the full potential of the panels?
The mpt-7210 can't charge a 3s or a 4s battery really not usable until 7s. Perhaps I missed it Did the battery change from 3s/4s to7 s? The voltage of the solar panels has to be lower than the voltage of the battery.
 later floyd
Good point - mpt-7210a - should work for 4s as that's above the 12v range but not good for 3s.   There are several youtubes on the mpt-7210a and they might answer the question of 4s explicitly.

@dbldrew - the fundamental problem underlying all this is that 18650 lithium-ion is *just not suited* for easy 12v solutions.   This is why folks tend toward LifePO4 for 12v solutions, where the voltage range so much more compatible with 'just standard stuff' Smile       FYI - they do make LifePO4 18650 container formats - and/or some pouch cells and/or blocks (of LifePo4) are pretty available.   Not sure why you're on 18650 lithium-ion but if you haven't purchased cells you - you might want to give that a look.
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#12
(06-05-2020, 10:02 PM)OffGridInTheCity Wrote:
(06-05-2020, 09:43 PM)floydR Wrote:
(06-05-2020, 05:25 PM)dbldrew Wrote:
(06-05-2020, 03:53 PM)OffGridInTheCity Wrote: Another one that is cheaper, fully programmable is the famous MPT-7210a  (many youtubes on this).  Its limited to 10a on output but is fully programmable - and you could do 2 in parallel if you like the 1st one.    https://www.ebay.com/itm/LCD-MPT-7210A-M...Swe9tepqNQ

if i get the MPT-7210a would there be any issue with running the 4 - 50W panels that could produce more amps then the output of the controller? Or is it just not getting the full potential of the panels?
The mpt-7210 can't charge a 3s or a 4s battery really not usable until 7s. Perhaps I missed it Did the battery change from 3s/4s to7 s? The voltage of the solar panels has to be lower than the voltage of the battery.
 later floyd
Good point - mpt-7210a - should work for 4s as that's above the 12v range but not good for 3s.   There are several youtubes on the mpt-7210a and they might answer the question of 4s explicitly.

@dbldrew - the fundamental problem underlying all this is that 18650 lithium-ion is *just not suited* for easy 12v solutions.   This is why folks tend toward LifePO4 for 12v solutions, where the voltage range so much more compatible with 'just standard stuff' Smile       FYI - they do make LifePO4 18650 container formats - and/or some pouch cells and/or blocks (of LifePo4) are pretty available.   Not sure why you're on 18650 lithium-ion but if you haven't purchased cells you - you might want to give that a look.

I already have a bunch of 18650 but not enough to build the battery bank yet. So If I switch over to 26650 instead, that voltage will work with any solar charge controller? Or do i still need a specific LifePO4 solar charge controller?
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#13
There are many 12v lifepo4 Solar charge controllers https://www.ebay.com/sch/i.html?_from=R4...2v+charger

Later floyd
OffGridInTheCity likes this post
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#14
For 12v, LifePO4 is the way to go.   If you're wondering where to get cells - here's a good example of A123(s) you can salvage from a recommended place
https://batteryhookup.com/collections/li...r26650m1-b

And here's a recent youtube on salvaging the cells from this type of pack - NEC Energy Solutions A123 LiFePO4 Batteries, Cell Harvesting (Battery Hookup) - https://youtu.be/3jPYyGjWqck  - 

Not pushing this, just showing an example of reasonable price and reliable source you could use to build a nice 4s pack.  These cells are around 2500mah each.  To build a 100ah 12v battery you would need aprox 4s40p  (e.g. 160 of these cells) Or 1/2 that for 50ah.  At 50a/cell max discharge it would give you all the power a trolling motor could want.
Another advantage of LifePO4 that I read all the time is you can discharge them near 100% - e.g. deeper even than Lithium-Ion.
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#15
(06-05-2020, 11:30 PM)OffGridInTheCity Wrote: For 12v, LifePO4 is the way to go.   If you're wondering where to get cells - here's a good example of A123(s) you can salvage from a recommended place
https://batteryhookup.com/collections/li...r26650m1-b

And here's a recent youtube on salvaging the cells from this type of pack - NEC Energy Solutions A123 LiFePO4 Batteries, Cell Harvesting (Battery Hookup) - https://youtu.be/3jPYyGjWqck  - 

Not pushing this, just showing an example of reasonable price and reliable source you could use to build a nice 4s pack.  These cells are around 2500mah each.  To build a 100ah 12v battery you would need aprox 4s40p  (e.g. 160 of these cells). 

thats funny thats exactly where I ordered my cells from.

I ordered 96 of them, so depending on how many turn out good I could make either 1 bigger pack or 2 smaller battery packs. guess maybe I could make a 3s 18650 pack as well as a reserve with the cells I already have.
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#16
(06-05-2020, 11:40 PM)dbldrew Wrote:
(06-05-2020, 11:30 PM)OffGridInTheCity Wrote: For 12v, LifePO4 is the way to go.   If you're wondering where to get cells - here's a good example of A123(s) you can salvage from a recommended place
https://batteryhookup.com/collections/li...r26650m1-b

And here's a recent youtube on salvaging the cells from this type of pack - NEC Energy Solutions A123 LiFePO4 Batteries, Cell Harvesting (Battery Hookup) - https://youtu.be/3jPYyGjWqck  - 

Not pushing this, just showing an example of reasonable price and reliable source you could use to build a nice 4s pack.  These cells are around 2500mah each.  To build a 100ah 12v battery you would need aprox 4s40p  (e.g. 160 of these cells). 

thats funny thats exactly where I ordered my cells from.

I ordered 96 of them, so depending on how many turn out good I could make either 1 bigger pack or 2 smaller battery packs. guess maybe I could make a 3s 18650 pack as well as a reserve with the cells I already have.
Cool Smile     Maybe you could use 18650 as 4s or 5s or whatever so they are aproximately the same voltage as the 200w panels.   Then, I believe you could plug them into the charge controller where you'd normally feed in the panels - and use their power to recharge the 12v pack if the sun is down.

In any case, it would be fun to read some updates and/or some pics of your project if you are so inclined.
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#17
Assuming it’s a basic brushed motor unit with the usual 3to5 fixed speeds, I would recommend 4s Lion over 3s. This is from my own experience with the same application. The motors can handle the overvoltage just perhaps not for long continuous periods (in fact many folks use 4s and aren’t conservative w/ throttle yet have no problems). 3S is great till the voltage drops then the power loss is significant at nominal cell voltage and below. And in this application you want to use the batteries not nurse them like a powerwall. You want max capacity to weight ratio which favors lion with full 4.2v charge and the ability to take them to 3v if you need - without losing all your thrust first.

You can buy a cheap 60A PWM controller board from amazon or eBay for under 20bucks (i like the red one ; amazon has it under the DROK brand) and use it to control speed with the motor always set to full speed. Only use the motors own control for shifting between off / fwd / reverse. Just make a note of the potentiometer position that matches up with normal full 12v speed and mark it - anything higher than that is your reserve / turbo for short burst use.

This will save your a ton of power versus using the motor at lower than full speed, where the motor just burns off excess power through big resistors.

The only trick is figuring out how to waterproof the pwm board without covering up the heat sink. not trivial. because of this , and because the pwm boards can fail, implement it in a way that you can bypass it whilst on the water without too much effort , so you can get home.
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#18
(06-09-2020, 04:49 PM)ttbloker Wrote: Assuming it’s a basic brushed motor unit with the usual 3to5 fixed speeds, I would recommend 4s Lion over 3s. This is from my own experience with the same application. The motors can handle the overvoltage just perhaps not for long continuous periods (in fact many folks use 4s and aren’t conservative w/ throttle yet have no problems). 3S is great till the voltage drops then the power loss is significant at nominal cell voltage and below. And in this application you want to use the batteries not nurse them like a powerwall. You want max capacity to weight ratio which favors lion with full 4.2v charge and the ability to take them to 3v if you need - without losing all your thrust first.

You can buy a cheap 60A PWM controller board from amazon or eBay for under 20bucks (i like the red one ; amazon has it under the DROK brand) and use it to control speed with the motor always set to full speed. Only use the motors own control for shifting between off / fwd / reverse. Just make a note of the potentiometer position that matches up with normal full 12v speed and mark it - anything higher than that is your reserve / turbo for short burst use.

This will save your a ton of power versus using the motor at lower than full speed, where the motor just burns off excess power through big resistors.

The only trick is figuring out how to waterproof the pwm board without covering up the heat sink. not trivial. because of this , and because the pwm boards can fail, implement it in a way that you can bypass it whilst on the water without too much effort , so you can get home.

yes the motor is a 30lb thrust 5 speed. And that was my worry with the 3s being too low in voltage. Now one of my battery banks is going to be made with 26650 cells 4s so that will give a perfect voltage range. But my other battery that Im building is going to be made from 18650 cells so I'm thinking of going with 4s with that one as well.

Now the solar charge controller I picked up was the renogy wanderer wnd30-LI its a 30A charger that does LifePO4 (along with lead acid) but it also has an app that I can make custom charge settings for different battery types.

So I can set the high voltage disconnect to 16.8
Charge limit voltage has a MAX of 17V
I can also set the equalize charge volts
Boost Charge volts
float charge volts

Everything has a max of 17 volt option. So what would the best setting be for a 4s 18650 pack?

I understand that with only having a max of 17v charge limit it would probably take forever to reach the full 16.8v. But thats ok if it could charge to 80% or higher in a reasonable time then that will work for what Im using it for. Would rather have a 4s @~80% charge then a 3s @100% due to the better voltage. Besides this is the back up battery pack and the 26650 pack is going to be the main pack
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#19
(06-09-2020, 10:50 PM)dbldrew Wrote: So I can set the high voltage disconnect to 16.8
Charge limit voltage has a MAX of 17V
I can also set the equalize charge volts
Boost Charge volts
float charge volts

Everything has a max of 17 volt option. So what would the best setting be for a 4s 18650 pack?

I understand that with only having a max of 17v charge limit it would probably take forever to reach the full 16.8v. But thats ok if it could charge to 80% or higher in a reasonable time then that will work for what Im using it for. Would rather have a 4s @~80% charge then a 3s @100% due to the better voltage. Besides this is the back up battery pack and the 26650 pack is going to be the main pack
You don't want to charge to 17v as that's 4.25v/cells - e.g. greater than 4.2v/cell.   Lithimum is dangerous if it's charged above it's max and will rapidily shorten it's number of cycles.

For 18650 I would max out at 4.15v * 4 = 16.6.    For longer live - maybe 4.10v * 4 = 16.4v - and give a bit of wiggle room if cells become a bit unblanced.\
For LifePo4, it has a much flatter voltage/discharge curve - just be sure to stay below the max voltage / cell * 4. 


For either 18650 or LifePo4 (Lithium in general) - you don't want Equalize at all (this is a lead acid thing) and I believe Boost is a lead acid thing as well.   Make sure Equalize is off (maybe set to 0) and either turn Boost off or make sure its <max.

Float is what you want.   This should do Constant Voltage - e.g. it will charge up to this voltage and then not go any higher...  e.g.  hold that voltage but slowly reduce current as the battery fills that last bit.   You might find that the Float value is tied to Boost or Absorb or something..  like Absorb has to be .1v higher than Float.  Focus on Float and get it as close to max as you can but don't let anything else go above your max for the battery. 

*What happens is a charger will raise the voltage higher than the current battery voltage - to allow max current to flow in.   Float is the end of the process where the voltage maxes out at the top voltage you set...  and then as the battery approaches that voltage the current will get less and less unit the battery is at the float voltage and current is basically 0.   This is 'full battery'.  


P.S. Sounds like great progress - look forward to hearing that it all worked 'in action' Smile
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#20
(06-09-2020, 11:17 PM)OffGridInTheCity Wrote:
(06-09-2020, 10:50 PM)dbldrew Wrote: So I can set the high voltage disconnect to 16.8
Charge limit voltage has a MAX of 17V
I can also set the equalize charge volts
Boost Charge volts
float charge volts

Everything has a max of 17 volt option. So what would the best setting be for a 4s 18650 pack?

I understand that with only having a max of 17v charge limit it would probably take forever to reach the full 16.8v. But thats ok if it could charge to 80% or higher in a reasonable time then that will work for what Im using it for. Would rather have a 4s @~80% charge then a 3s @100% due to the better voltage. Besides this is the back up battery pack and the 26650 pack is going to be the main pack
You don't want to charge to 17v as that's 4.25v/cells - e.g. greater than 4.2v/cell.   Lithimum is dangerous if it's charged above it's max and will rapidily shorten it's number of cycles.

For 18650 I would max out at 4.15v * 4 = 16.6.    For longer live - maybe 4.10v * 4 = 16.4v - and give a bit of wiggle room if cells become a bit unblanced.\
For LifePo4, it has a much flatter voltage/discharge curve - just be sure to stay below the max voltage / cell * 4. 


For either 18650 or LifePo4 (Lithium in general) - you don't want Equalize at all (this is a lead acid thing) and I believe Boost is a lead acid thing as well.   Make sure Equalize is off (maybe set to 0) and either turn Boost off or make sure its <max.

Float is what you want.   This should do Constant Voltage - e.g. it will charge up to this voltage and then not go any higher...  e.g.  hold that voltage but slowly reduce current as the battery fills that last bit.   You might find that the Float value is tied to Boost or Absorb or something..  like Absorb has to be .1v higher than Float.  Focus on Float and get it as close to max as you can but don't let anything else go above your max for the battery. 

*What happens is a charger will raise the voltage higher than the current battery voltage - to allow max current to flow in.   Float is the end of the process where the voltage maxes out at the top voltage you set...  and then as the battery approaches that voltage the current will get less and less unit the battery is at the float voltage and current is basically 0.   This is 'full battery'.  


P.S. Sounds like great progress - look forward to hearing that it all worked 'in action' Smile

So just looking at the default settings for the LifePO4 it has equalize, boost and float all the same at 14.4v, the charge limit at 15.5v and high V disconnect at 16v

So im assuming i should probably keep equalize, boost, and float all the same value but at 16.4v high disconnect at 16.6? and charge volt limit was almost 1v higher for the LifePO4 so should that be set to higher voltage as well? like 16.6? or even higher and max it at 17?

And I cant wait to post back on the success! will def keep you guys updated
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