Picaxe Kayak Control Project

mikeyBoo

Senior Member
hi folks,
This project describes a kayak control system my buddy & I built last winter. We have enjoyed using it all summer & thought it might be interesting for folks to see just how much functionality could be squeezed out of a Picaxe processor.

I attempted to fully document the project, but the document quickly became book size, so I am posting a rather terse description of the project in the attached pdfs.

Sometimes one idea seems to just spawn another (& another), so by the time we were done, we had developed a plug & play control bus (KYK I2C) that works across Picaxe variants as well as a nice Picaxe project development system.

Since posting the entire project is impossible given the severe pdf attachment size restrictions, I am posting a (more or less) synopsis.

If anyone is interested in any of the boards illustrated in the project, let me know & I can do a per-device posting. All the boards shown are single-sided (albeit with some topside jumpers) & can be made fairly easy at home. Most PCB layouts were done with DipTrace & some were done with the rather ancient (but still by far the best) Tango. However, all can be uploaded as .pdf files.

Sorry I could only upload a glimpse of the project, but it only allowed 2 attachments per post.
 

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lbenson

Senior Member
Very nice project. Exceptionally well organized program for a picaxe.

Can you provide some pics of the kayak, trolling motor, and steering controls? I ask as someone who has kayaked for 47 years, but whose shoulders are now too wrecked to do much paddling.
 

techElder

Well-known member
Certainly a nice project.

I don't quite understand taking a normally 3-wire bus and making it an 8(or more)-wire bus.
 

mikeyBoo

Senior Member
Very nice project. Exceptionally well organized program for a picaxe.

Can you provide some pics of the kayak, trolling motor, and steering controls? I ask as someone who has kayaked for 47 years, but whose shoulders are now too wrecked to do much paddling.
hi Ibenson,
I attached a small .pdf showing how trolling motor is mounted.
I thought I could post the whole project but the file size restriction won’t allow it. Guess it will be one piece at a time as needed. The construction files have a lot of pics, so not sure I want to break them into little pieces. May have to have a plan B if anyone gets interested (post to Native site?).

“Picaxe Kayak Control System part 1.pdf” contains info on how to operate the controller.
By the way, I’ve been using the Picaxe controller since early spring & I’ll never go back to paddling/pedaling. You just drop a line each side of yak, then sit back, smoke a cigar, listen to music, enjoy the quiet ride.
 

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mikeyBoo

Senior Member
Certainly a nice project.

I don't quite understand taking a normally 3-wire bus and making it an 8(or more)-wire bus.
hi Tex,
See “Picaxe Kayak Control System part 2.pdf” for explanation of KYK bus.

The 3-wire I2C bus is not fault-tolerant. This means if the I2C bus locks up, the Picaxe loses control of other devices on the bus (bad news if you’re controlling motors or actuators).

The KYK I2C adds control signal AOE that can be used to shut off power to motors, valves, whatever, in case of an I2C bus fault etc. SRST (system reset) can also hard-reset many devices. It’s a safety thang’.
A cable comes unplugged or Picaxe goes belly-up, it’s good if power devices shut down.

Additionally, since many I2C devices are smart, they can issue a SREQ (service request) so the Picaxe does not have to keep polling a lot of I2C drops. Unused SREQs can be used as needed (I use 2 of them for OLED comm & real-time clock pulse on the kayak project).
Also lets hardware/software be shared across Picaxe variants.
Lots of other reasons, but above is major stuff.
 

mikeyBoo

Senior Member
Thanks for posting the pdf with pics. Nice rig & great project.
thanks & good morning,

The start of the project with pictures & attachments is on this site (However, they require a login before seeing pics/attachs, but it's free)
http://nativeownersgroup.com/topic/4820-using-trolling-motor-on-mariner/

I am thinking about just uploading the rest of the project there since they don't have all the size restrictions as on this sight. However, most kayakers are not technical folks, so it wouldn't see much use.
 

mikeyBoo

Senior Member
I know that you have it all figured out, but why I2C and not just use serial comms?
good morning,
I2C is to serial comms as a horse is to a car. The I2C is much faster, way more expandable, & offers a lot more options. You could easily put a hundred devices on the I2C bus, but that would be a challenge with serial comms. It's also easy to do circuit boards for I2C devices (a plus for me since I'd rather be fishing).
Attached are the schematics for the Picaxe-20M2 board & joystick DIO board used on this project. As you can see, there ain't a whole of lot of complexity.
Have a fun day!
 

Attachments

erco

Senior Member
Great project and terrific documentation! You should post a video of the kayak & controller in use, that would really complete the presentation.
 

fernando_g

Senior Member
I agree with the others: TERRIFIC and well documented project.
I'm glad that you could merge both your passions into this project.

Like your "mama trees" software strategy. Very intuitive. Shows all the experience accumulated during your working years.

One question; how did you protect the boards against humidity?
For the connectors on my environmentally-exposed projects I've always used some moly-grease (Nyogel 76V) to protect them; with excellent results.
 

mikeyBoo

Senior Member
thanks guys,
Yep, “mama trees” is easier to get your head around than “hierarchical procedural structure”. Anyhow, words with over 3 syllables have to be contracted in southern English (i.e. hi-rar-cul pro-see-drul struc-cher).
Haven’t had any problems with moisture or condensation. The battery & drive electronics are in a sealed box with a fan that runs when the drive is turned on. The (Northern Tools) box does not hold heat very well (a good thing), so it all stays dry. The DB connectors slide into each other so no problem there. I did put dessicant packs in the joystick & display cases.
My next step is to add a GPS auto-pilot. It will be a Raspberry Pi Zero project. This should allow the yak to drive itself from waypoint to waypoint & spot-lock at any position on the water. I could do the same thing by adding another Picaxe in the joystick box, but the math would be a pain & no wireless GPS control panel on my Kindle.
The KYK IDC10 bus (described in the yak project) means I simply have to remove the Picaxe-20M2 board & replace it with a Pi board (with a KYK connector & level adapters) when I upgrade. I like the concept of IO hardware being processor independent.
When it gets warm enough to fish at night, I’ll get my buddy to video the orange yak. With the effects running it looks like a UFO halloween pumpkin on the water (comical but good for fishing).
The secret to world peace: Nations’ leaders should be fishing buddies.
 

fernando_g

Senior Member
thanks guys,

The secret to world peace: Nations’ leaders should be fishing buddies.
Amen, Bro!

The Japanese have a variant; taking a hot bath together.

The Japanese Prime Minister had hinted he would invite Vladimir Putin for a hot bath to discuss the Kuril Islands. Don't know if the meeting ever occurred, but to my knowledge, the Kurils remain solidly Russian.
 

mikeyBoo

Senior Member
Yes, still catching fish with it. Decided to stay with the Picaxe-20M2 controller instead of moving to the Pi since it's been so reliable & uses much less current. The drive only draws 2.5 Amps when I'm trolling 2 rods. The battery always lasts longer than I do.
Made some minor upgrades: 5 buttons instead of joystick, different amp sensor, combined analog input & drive controller, few software revisions. Not sure how many folks on this site are into "Picaxe fishing tech".
Are fishing-related projects of interest to anyone else?
 

Yex2

Well-known member
Not sure how many folks on this site are into "Picaxe fishing tech".
Are fishing-related projects of interest to anyone else?
I'm a picaxe fishing low tech kind of guy...

Here is my realization : 14', it weight ± 40 lbs. I was aiming at 35 lbs but I think I exaggerated on the Epoxy



It only require a single paddle an a few beers to operate nicely all day long. :ROFLMAO:

More pictures here if you want to check it out
 
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mikeyBoo

Senior Member
hi Yex2,
Now that’s a good-looking ride!
Sometimes it’s great to just paddle around in a shady cove enjoying nature.
My idea of heaven is drifting down a slow-moving river with Mark Twain (fishing & smoking stogies).

The reason I put a trolling motor on my yak is that in the deep south (USA) the summers are brutal (very high temps & humidity).
In the summer heat I troll deep water with a sun shade & a fan blowing on my back so it’s pleasant even in 100degF weather.
I have a pressure pump that vaporizes water that I use as an “air conditioner” on my riding mower, but haven’t needed it on the yak yet. Being close to the water (yaks/canoes) seems to have a cool zone that works well enough with just a fan or even a breeze.

Most of my projects are done in winter when it’s too cold to fish.
Maybe I need to do a project on just the drive board from this yak project since it can control a PWM drive, a servo, interlock (e-stop/run) in/out, and read battery voltage & current all from the C port of a Picaxe-20M2. Might be fun to see what other folks could do with that.

I have a hard time figuring out what other folks are interested in on this site.
The Brits seem more reserved (we Americans never shut up & I don’t want to appear pushy).

Anyhow, here’s some ideas I had for future projects, if anyone has similar interests, let me know.
It’s fun to brainstorm on new ideas before starting a project.

Ideas for Picaxe Projects:
01 enslaved Picaxe
lets your PC (via graphical or terminal pgm) interactively control a Picaxe(s) resources.
e.g. send or receive I2C data, generate PWM or frequency, set/get digital/analog, let Picaxe invoke apps on
your PC, etc. Test new devices without having to download or simply use Picaxe(s) as IO device(s) to PC

02 Picaxe calibrator
plugs directly into DVM, DVM display shows outputted value (volts, mA, freq, etc.)
3-posit switch allows Lo-Mid-Hi calib values (connect to PC for fancier stuff per item 01 e.g. freq generator or servo tester)

03 (Off-topic) An alternative to the Picaxe when you need floating-point math or easy assembly-language interfacing but
want to remain in the comfort of BASIC. (using MCS-BASIC with 8052 chips)

04 What is KYK & why it’s a good idea (from this yak project)

05 Off-topic but very useful: How to get hyper-organized (creating time & making things happen fast)

06 Picaxe-controlled (via RF) planer for fishing fun (simply a small rudder on rear of planer)
08M2 on planer could do zig-zags, stop & go, etc.

07 Picaxe (via RF) fish attractor
(red/green LEDs mounted on bottom of floater or boat, Picaxe does effects & intensity commands (e.g. slow-glow, blink, etc.)

08 remote-controlled weed-eater
(single front wheel controlled by servo or linear actuator, 2 rear wheels are driven)
counter on drive wheel allows distance travelled to be known & servo allows very sharp turning, so possible to make an autonomous mower

09 Battery Load-Tester
Input max test length & dropout voltage (at end of test shows: AmpHours supplied, test stop time)

10 Crotch-biting robot guard dogs
(as well as producing forensic evidence would make a tasty treat for my real dogs)

11 Ultimate Fishing Accessory: small laser-guided missile rack for eliminating jet-skis

Ok… all seriousness aside (I don’t do serious) items 10 & 11 may be a bridge too far, but my point is there are still lots of fun things to be done with Picaxe chips.

Keep in mind that some folks can’t see what doesn’t already exist & will feel compelled to criticize or invalidate.
So folks, please respect everyone’s opinion (including mine), no matter how stupid you think it is.
 

lbenson

Senior Member
Not sure how many folks on this site are into "Picaxe fishing tech".
Are fishing-related projects of interest to anyone else?
I'm in.

I rigged an outboard picaxe-controlled electric trolling motor onto the kayak pictured below. In a moderate breeze it needed supplemental paddling and so wasn't altogether satisfactory (kevlar "pokeboat"--23 pounds; not lovely now after 30 years and many rocks crawled over, but a friend told me that she knew women whose purses weighed more).
23098
On the Medway river in Nova Scotia.

Beautiful boat, Yex.
 

Yex2

Well-known member
Ideas for Picaxe Projects:

07 Picaxe (via RF) fish attractor
(red/green LEDs mounted on bottom of floater or boat, Picaxe does effects & intensity commands (e.g. slow-glow, blink, etc.)
I was thinking of doing one like this including vibration. However it would be illegal to use here... :eek:

08 remote-controlled weed-eater
(single front wheel controlled by servo or linear actuator, 2 rear wheels are driven)
counter on drive wheel allows distance travelled to be known & servo allows very sharp turning, so possible to make an autonomous mower
Last night I had to promise my wife that I would try to build an automatic land mower a bit like those vaccum cleaner "Roomba". I'm at the cabin at the moment and she's complaining the grass is getting long... :rolleyes:


09 Battery Load-Tester
Input max test length & dropout voltage (at end of test shows: AmpHours supplied, test stop time)
Don't need a picaxe for that. A simple resistance would do. If voltage fall bellow a certain threshold, then the battery is dead!



10 Crotch-biting robot guard dogs
(as well as producing forensic evidence would make a tasty treat for my real dogs)
Actually my next project is this : I will be using my solar panel to detect the night. Once the night is detected several things will happen:

A) for the cabin : turn on several light in various sequence. The radio as well. All to simulate my presence when I'm not there. I wold also to use motion detector that would play sound such as a very nasty dog barking, then a lignt that turn on and a man's voice that says something like: "Honny pass me the shut gun, there someone out..."

B) for the boat: Turn on the mooring light until daybreak. Turn on the cockpit light until midnight (you have no idea how many time I didn't find my boat when I return late and no light were on. Also motion detector to play similar sound as for the cabin.

But right now I have to finish my current project. It's a device to make people aware of their water consumption. It's count the quantity of water they take for there showers. It record minimum & maximum water consumption. I made two version.

One for the cabin, it record each shower consumption after 3 minutes of inactivity. The boat version records the water consumption of each cabins after 24 hours period. The boat version will also relay each cabin info to a main display at the cockpit table so I don't have to go see each cabins. And I will be able to have my guest compete against each other for a bottle of Champagne :p for the coupe who took the least water... ;)



11 Ultimate Fishing Accessory: small laser-guided missile rack for eliminating jet-skis
That is a good idea (y)

An interesting project I was thinking the other day would be to build an autonomous "lamprey killer" mini submarine. It could have solar panel to recharge during the day and go hunting during the night. If we could make one that work, I'm sure we could sale an armada to both US & Canada fishing authorities. The lamprey are killing steel head trouts in the Great lakes and they have no predators. The steel head is bound to extinction unless we find a way to illiminate that invasive species that come from Europe I think.
 

Yex2

Well-known member
I rigged an outboard picaxe-controlled electric trolling motor onto the kayak pictured below. In a moderate breeze it needed supplemental paddling and so wasn't altogether satisfactory (kevlar "pokeboat"--23 pounds; not lovely now after 30 years and many rocks crawled over, but a friend told me that she knew women whose purses weighed more).
Ha ha ha...

Beautiful boat, Yex.
Thanks ! Handle well too.
 

mikeyBoo

Senior Member
Hi guys, Sounds like we are on the same page (or water… whatever)

Uh Ibenson, methinks something is amiss with your trolling motor setup. My yak weighs 4x that much & I never go over 50% PWM in a high wind & never need a paddle. With a yak that light, it should be jumping out of the water (i.e. 0…hull speed in ‘bout 3 seconds). In fact (being that light) you should need flaps & ailerons to get on plane!
If my memory is correct, I’m running my PWM at ~4KHz which works best with my Minn Kota & drive pak.

Maybe I need to post a project on just the propulsion section of my setup, then part 2 on the steering.

Usually the best projects begin with a bunch of wild & crazy ideas.
Y’all have a fun weekend on the water (I know I will)
A miniature submarine… Hmmm…. gotta' have a camera... spear gun? Naaa... better not.
 

Yex2

Well-known member
A miniature submarine… Hmmm…. gotta' have a camera... spear gun? Naaa... better not.
Sonar would make sense... and some kind of jaw to cut the snake on two :devilish:

But I admit, the homing system would be a challenge...
 
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lbenson

Senior Member
Uh Ibenson, methinks something is amiss with your trolling motor setup. My yak weighs 4x that much & I never go over 50% PWM in a high wind & never need a paddle.
I think my biggest problem is that the motor is outboard to the side immediately behind me, so there's torque. If it were centered, all might be well, but I'd either have to go through the hull or cut off the back and make a transom. With rocky river kayaking, I probably wouldn't do well with something I couldn't lift up.
 

Yex2

Well-known member
I think my biggest problem is that the motor is outboard to the side immediately behind me, so there's torque. If it were centered, all might be well, but I'd either have to go through the hull or cut off the back and make a transom. With rocky river kayaking, I probably wouldn't do well with something I couldn't lift up.
Why not using a bracket system that could lift up the engine? Also it would be centered.

I think mikeyBoo uses that. I saw it in one of the picture he posted.
 

mikeyBoo

Senior Member
KYK_TMI2 Trolling Motor Interface Board
A lil’ “rainy day” project. (The interface board I designed for my trolling motor drive)

This project may be of interest if you need to control the speed & direction of a motor with a Picaxe (or other uProc). Although I used this interface board for the steering & propulsion of a trolling motor, it would certainly work in various unrelated applications (e.g. remote-control weedeater, killer robot dog for zombies, other common applications).

The KYK_TMI2 board (when connected to a Picaxe-20M2 port C) provides the following functions:
01 a variable duty-cycle PWM signal for controlling motor speed
02 motor forward/reverse selection
03 servo control signal for steering the motor
04 analog scaling for reading battery or motor amps
05 analog scaling for reading battery volts
06 Although port C pins C.4 & C.6 are not required for functions 01...05, they are accessible via H3 & H4 if
needed (e.g. interlock control, info to display, lights On/Off, etc.).

I attached an updated copy of the kayak control software Picaxe Kayak Control System.bas that can be used to get an understanding of how to control speed & direction with a Picaxe-20M2. The only major change from the original version is that I replaced the joystick with 5 pushbuttons. This works better for fishing.
(e.g. “step left” button to make an arc around the fish I’m reeling in, “center” button to go straight after a turn, etc.)

The software is pretty simple:
Hardware config is done in init at startup.
The endless loop main is used to read inputs & update outputs

Speed is controlled via procs beginning with “TMotor.speed
(e.g. TMotor.speed_Set TMotor.speed_Decrease TMotor.speed_Increase etc.)

Steering is controlled via procs beginning with “TMotor.servo
(e.g. TMotor.servoPosition_Set TMotor.servo_StepLeft TMotor.servo_StepRight etc.)
 

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newplumber

Senior Member
KYK_TMI2 Trolling Motor Interface Board
A lil’ “rainy day” project. (The interface board I designed for my trolling motor drive)

This project may be of interest if you need to control the speed & direction of a motor with a Picaxe (or other uProc). Although I used this interface board for the steering & propulsion of a trolling motor, it would certainly work in various unrelated applications (e.g. remote-control weedeater, killer robot dog for zombies, other common applications).

The KYK_TMI2 board (when connected to a Picaxe-20M2 port C) provides the following functions:
01 a variable duty-cycle PWM signal for controlling motor speed
02 motor forward/reverse selection
03 servo control signal for steering the motor
04 analog scaling for reading battery or motor amps
05 analog scaling for reading battery volts
06 Although port C pins C.4 & C.6 are not required for functions 01...05, they are accessible via H3 & H4 if
needed (e.g. interlock control, info to display, lights On/Off, etc.).

I attached an updated copy of the kayak control software Picaxe Kayak Control System.bas that can be used to get an understanding of how to control speed & direction with a Picaxe-20M2. The only major change from the original version is that I replaced the joystick with 5 pushbuttons. This works better for fishing.
(e.g. “step left” button to make an arc around the fish I’m reeling in, “center” button to go straight after a turn, etc.)

The software is pretty simple:
Hardware config is done in init at startup.
The endless loop main is used to read inputs & update outputs

Speed is controlled via procs beginning with “TMotor.speed
(e.g. TMotor.speed_Set TMotor.speed_Decrease TMotor.speed_Increase etc.)

Steering is controlled via procs beginning with “TMotor.servo
(e.g. TMotor.servoPosition_Set TMotor.servo_StepLeft TMotor.servo_StepRight etc.)
right on Mikey thanks for posting
I have the boat next to the shop but have to get the shop cleaned out to fit it in then
phase 1 begins strip boat
phase 4 - build a controller like yours
 

mikeyBoo

Senior Member
hi newplumber,
That boat should be perfect for an electrical conversion. Looks like you like to have fun with your projects (me too).

The little drives I use might not be big enough for your boat, but the interface could be used with bigger drives by using an adapter cable. I wonder if you paralleled 4 drives to 4 trolling motors & ran them on +24v if that might do the trick? However… more motors, more batteries, more $money. (Hey, wouldn't be any fun if it was easy.)

I haven’t made the transition to lithium batteries yet after seeing what happened when my gal friend threw her phone into a rock (didn’t know a phone could be a hand grenade) & watching the Chevy Bolt EV fires. Guess I’m gonna’ stick with deep-cycle AGMs.

When it gets too cold to fish, I’m gonna’ do a version 3 of the interface board because I need to use C.0 to drive an mp3 player giving the option of voice output from the Picaxe controller (e.g. “low bat, left-2, S50, theme from Jaws”, etc.).

I really believe if a guy’s head is hard enough, he can accomplish anything! Although I have had a few “Fred Flintstone” knots on my head over the years.

Good luck with your project & let us know how it’s going.
 

papaof2

Senior Member
LiFePO4 batteries are the most stable of the commonly available lithium family. LTO (Lithoum Titanate Oxide) is the next generation and they're "expected" to have a life of 20,000 charge/discharge cycles. At one cycle/day, that's 54+ years so these might truky be "lifetime" batteries ;-)

Phones tend to use lithium polymer (least stable and most prone to fire) because they're the most energy dense and thus the smallest and lightest for XX watt hours.

I got my feet wet with the LFP's this year when I needed to replace the 12 volt 4.3AH AGM battery in a small (now discontinued) UPS (APC BGE-70) which was designed for low power and long backup - 15 watts for 2+ hours, 7 watts for 8 hours. Too small to be useful? Think backup for a home alarm console or a single mains-powered security camera. The manufacturer wanted $50US + shipping and the aftermarket price was $27US + shipping. I found 3.8AH LFP cells at batteryhookup.com for under $3US each (delivered). An AGM has very short life in UPS service because the UPS is usually designed to get the maximum possible power (minutes of backup) from its battery and AGM's have short lives (number of charge/discharge cycles) at 80% or greater discharge and the very fast recharge most UPS designs use. Four nominal 3.2 volt LFP cells are a direct replacement for a 12 volt battery so I added a BMS and had a replacement battery pack for under $20US. The LFP cells should last at least 2000 charge/discharge cycles at 80% DOD and that might be longer than the UPS itself lasts ;-)

LFP does have a cold weather limitation - they shouldn't be charged at temperatures below 32F/0C - it's fine to use them below that temperature. A good BMS will have temperature sensing so low temperature charging doesn't happen.

aliexpress.com has some seemingly good prices on larger LFP cells (from Liito Kala, a company that's been in the battery charger/tester business for a long time) - sixteen 100AH cells for about $1500US delivered. Add a BMS per battery and you could have 400AH at 12 volts or 200AH at 24 volts or 100AH at 48 volts. They have larger cells - at least up to 320AH.
 

lbenson

Senior Member
papaof2--this is terrific information. Can you post your project (or link to where you have posted it?) Even if it doesn't have a Picaxe in it, you could say "this BMS function could be performed by a Picaxe".

Is this the right battery and am I reading this right (assuming "truth in advertising, haha"):
24873
For instance, 8 batteries with 2 pairs paralleled of 4 batteries in series giving a nominal 12.8 volts and 640 amp hours or 7.68 kilowatt hours for about $390 shipped to the U.S.?

This is exactly what I've been looking for. Is there a battery management system available for this arrangement? Even at half the rated KWhr, they would be useful to me.
 
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mikeyBoo

Senior Member
papaof2 presented some very useful info. Battery research is on fire now, if solid-state pans out, the slate is cleaned (go Toyota).

Here's a ready-to-go LiFePO4 system (UPS, solar charging, inverter, etc.) that I found interesting.
BLUETTI EP500 5120wh LiFePO4 UPS BACKUP Off Grid Solar Generator (very expandable)

However, for my yak, I'm still going to stick with the Optima AGM since I don't have to be concerned about ambient temperature or a battery management system. The battery & Picaxe controller are in a single box, so if I have a problem on the water, I just unplug the cables & hook up another box (simplicity is a big deal on the water, especially when it's cold).
Now, on a larger boat, well that's a different game.
 

lbenson

Senior Member
MikeyBoo--that's a terrific piece of gear. $2800 on kickstarter with a 30% discount. Before papaof2's post I would have thought that was a great price. And actually, with all it's features, I still think it's a terrific price with all of the hard work done for you.
 

papaof2

Senior Member
papaof2--this is terrific information. Can you post your project (or link to where you have posted it?) Even if it doesn't have a Picaxe in it, you could say "this BMS function could be performed by a Picaxe".

Is this the right battery and am I reading this right (assuming "truth in advertising, haha"):
View attachment 24873
For instance, 8 batteries with 2 pairs paralleled of 4 batteries in series giving a nominal 12.8 volts and 640 amp hours or 7.68 kilowatt hours for about $390 shipped to the U.S.?

This is exactly what I've been looking for. Is there a battery management system available for this arrangement? Even at half the rated KWhr, they would be useful to me.
Search for offgrid garage on Youtube - he's in Australia and has purchased a number of Chinese-made LFP cells (not sure which brand) and has found them to be close to their rated specs.

Lots of BMS units at the 100 amp level, and a few above that. IF I had the $$$$, 16 cells would make four 12 volt batteries and a 100 amp BMS on each battery would handle more current than I need (maximum draw of the loaded 2000 watt pure sine wave inverter is 195 amps - 4 X 100amp BMS is twice that so plenty of cushion). Overkill (that's their name ;-) makes some very good BMS units with temperature control and Bluetooth for monitoring and setup - you can configure the BMS to your preference of when to start balancing the cells and the maximum and minimum voltages so if you'd rather charge each cell to 3.55 volts, that's available. (Typical LFP range is charge to 3.65, discharge to 2.5. Max charge voltage is around 4 volts/cell. The LFP cells achieve their rated AH capacity around 3.6 volts.)

Not really anything to post on the little LFP battery pack as I didn't even make a picture of it. The batteries are 26650 size so I got some spacers for them, charged each of them to 3.55 volts (not "full" but a good place for the initial top balance), used a 12-volt-battery-powered spot welder and nickel strip to assemble a 4s1p pack of LFP cells, soldered on the BMS wires, wrapped the pack in captan tape and used Velcro strips to hold the much smaller (and lighter) pack in place in the UPS case. This BMS (from Ebay) doesn't monitor temperature but the UPS will be used in conditioned space so no worries about charging the battery below 32F/0C. The BMS low voltage cutoff of 2.5 volts/cell (10.0 volts for the battery pack) is never reached because the UPS shuts down at 10.7 volts (near full discharge for an AGM). The BMS limits the charge voltage to 3.55 volts/cell (14.2 volts for the pack). The UPS charger goes to 14.8 volts (max for an AGM) so the BMS is needed when charging.

The BMS needs to read the voltage per cell to 0.01 volt - and the cells are stacked 4 for 12 volts, 8 for 24 volts, etc. - not sure how you'd do that with a PICAXE. Temperature measurement of the battery pack is easy with a DS18B20. The BMS also needs to monitor charge and discharge currents. Cell balance is also a nice feature and that needs to be worked out. Plus the ability to set the charge and discharge voltage limits and disconnect the battery pack in the event of over/under voltage or over current. That's probably do-able but for things at the 100 amp level, most people don't have experience with the wire, PCB trace or MOSFET sizes needed.

The Bluetti does put a lot of power in a semi-portable package. I don't have a need for portable power so my somewhat older solar backup system uses AGM batteries (future replacement would likely be LFP but that's some years away as I got 9 years of backup service (think: big UPS) from the previous set of AGMs. 12 volt, 420AH battery bank. 2000 watt pure sine wave inverter (+ spare), 1800 watts of solar panels (300 watts of panels out to keep the batteries topped off, more can be added in a long outage), MPPT charge controllers for more than 3000 watts of solar panels - just waiting for the $$$ to add those panels to the current stock. We have frequent but usually short power outages (under 4 hours). The solar backup system was in place for the 12 hour outage when we had 7-12 inches/18-30cm of snow (in an area that rarely sees more than 3 inches/7.5cm). Nice to be able to flip a few breakers to have backup power and not be shoveling 7 inches/18cm of snow in the dark at 30F/-1C to get a gasoline generator out of the shed.
 
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lbenson

Senior Member
Well, newplumber, once again you have started a thread to which there are interesting responses going a number of different directions. Hope you don't mind the meandering.

papaof2: "Search for offgrid garage on Youtube" -- great BMS video

I think I have to try this if I can figure out which is the 12V version.
 

newplumber

Senior Member
Well, newplumber, once again you have started a thread to which there are interesting responses going a number of different directions. Hope you don't mind the meandering.

papaof2: "Search for offgrid garage on Youtube" -- great BMS video

I think I have to try this if I can figure out which is the 12V version.
Ha I love every bit of all the response and its good info ....I wish I could understand more but its fun pretending
thanks mikey and papa and you ....and seems everyone needs a plumber so i have been busy
and I should tell my customers that they can make a donation for my boat because after I get done doing a repair at their
house they might need to borrow it :)
I think your right mikey ...4 or 6 trolling motors would be cool!
I'll try to update on my other post when i get stripping the aluminum pig
 

lbenson

Senior Member
@newplumber -- Here's another good video on a LiFePo4 system (and might even work on a boat):

I'm going to try this route for a power outage backup for my boiler and water pump. I found a probably-too-good-to-be-true deal on the LiFePo4 batteries, and even if they don't work out, learning about the other components of the system will make it worth it. In my unfinished, gravel floor basement I happen to have the perfect "containment vessel" for the batteries--a 4-foot diameter sheet metal shell around a not-used-in-decades coal furnace.

(You've got me looking at the fiberglass runabout that's been sitting overgrown with weeds in a yard about a quarter mile from me for 10 years. I should probably put that thought out of mind.)
 

mikeyBoo

Senior Member
hi Ibenson, newplumber, & the rest
Y’all be sure & post your projects (I’m always looking for new ideas).

Ideally, an electric boat would have a connector that allows quick battery attachment to your home backup power system (if you trailer your boat or live near the water). I use my kayak power-paks during power outages as a light version of this strategy (for powering 12v fans & LED light strips).

For-what-it’s-worth dept.:
The proc (aka subroutine) ampUsage_Update in the Picaxe Kayak Control System.bas app used in this project has a very accurate amp-hours calculation strategy. This is done using the 1 second output signal from a DS1307 clock chip.
The proc could be modified to display kW hours using the simple formula Wh = Ah*V.

Amp hour to Watt hour or Watt hour >Amp hour https://convert-formula.com/ah-wh
All manner of electrical conversions https://convert-formula.com/

I suspect that someone will (or has) come up with a technology that obsoletes all this battery stuff. However, disruptive technologies can destroy economic systems (e.g. the petro-dollar), so lets hope the “Men in Black” don’t visit before he/she puts it on the internet.

So, guess if I come up with a lure that makes bass dance on the water & bark, better just keep it to myself.
 

lbenson

Senior Member
So, guess if I come up with a lure that makes bass dance on the water & bark, better just keep it to myself.
I read about a guy catching monster stripers offshore who had made his own lure to sound like lobsters clacking (whatever that sounds like). But if you report barking bass, we're gonna want to know what you've been drinking or smoking.
 
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