Custom thermo fan and dual battery controller

[stuee]

Rather than pinch Nemesis's thread on melting fuse plastic I'm starting my own thread about my custom thermo fan and dual (well actually multiple) battery controller.

This stuff is sort of a hobby for me now seeing as my work involves industrial control systems and all the small cool stuff I did at uni is no longer practised.

The system is based around an Atmel ATMega128 microcontroller. It features 8 analogue to digital converters (4 for sensor inputs like engine temp and at a later date oil pressure, and 4 for battery voltages so I can control up to 4 batteries individually if needed), numerous digital io's for switches and general inputs and outputs, theres a few pwm outputs that I probably wont use at this stage.

When I finally fork out for the display (I've been looking at a range of touch screen's around 3" in size that will communicate through serial comms, which is another feature built into the board. The display will be used to display engine engine parameters (whatever is hooked up to the micro) and status of the thermo fans and batteries.

The hardware that I've put together so far is shown below:


All housed in an IP65 rated box that will sit under the drivers seat.

I'll post up later on how the various bits work but if there's anything else people want to know post up.

[tj81]

Ive been looking for a digital temperature display with fan controller for ages, and the best i could find was this one:

http://cgi.ebay.com.au/JAW-IZUMA-Water- ... 7C294%3A50

There's also a similar one.

What i want it to do, is control a set of AU Falcon thermo fans, and be able to set the hysteresis to what i want for each fan. The ones above a ok for a single fan, or running 2 fans at the same time with the same temps etc, but id like to be able to set one fan to come on with normal operating temp, and the other when the need arises, and or the air con is turned on.

Is it possible using the Kit you supply? If so what type of sensors are required for non EFI vehicles ?

[stuee]

Ive been looking for a digital temperature display with fan controller for ages, and the best i could find was this one:

http://cgi.ebay.com.au/JAW-IZUMA-Water- ... 7C294%3A50

There's also a similar one.

What i want it to do, is control a set of AU Falcon thermo fans, and be able to set the hysteresis to what i want for each fan. The ones above a ok for a single fan, or running 2 fans at the same time with the same temps etc, but id like to be able to set one fan to come on with normal operating temp, and the other when the need arises, and or the air con is turned on.

Is it possible using the Kit you supply? If so what type of sensors are required for non EFI vehicles ?

Unfortunately I don't supply any kits of any sort. This is just something I'm doing for fun. I have been thinking about doing kits similar to what you described but to be honest I never really though the market was there seeing as most people just adapt whats already out there. Mind you if they can get $125 for that I may look into it more

My thermo fan controller will operate as you describe with adjustable hysteresis, only instead of switching the fans on separately it will have a low speed and high speed (Murcod gave me this idea and its achieved by running the relay setup in a slightly different way).

If your keen to run your fans separately have a look at what murcod has done as he's just wired up two jaycar voltage switch kits (that have built in hysteresis) to switch the fans separately. Alternatively if you don't want to tap into the factory temp sender you could use the temperature switch kits (only a couple of dollars extra), then you just need to run an aftermarket gauge.

I can post up more when I get home and link murcods threads but busy at work atm.

[stuee]

Here is a link to the relay wiring that I will be using (thanks once again to murcod). Still relies on two separate signals but operates as two speeds instead of two fans.

http://users.on.net/~murcod/XL-7/Thermo ... wiring.JPG

[murcod]

Wow Stuee, I thought mine was overkill!?

Keep the progress reports coming- I'm certainly interested. What sort of price do the parts you're using retail for and what language is that board programmed in- or is there some sort of interface software you can set it up via?

PS:
Here's a link to my system tj81: http://www.suzuki-forums.com/suzuki-vit ... fan-2.html

[stuee]

Wow Stuee, I thought mine was overkill!?

Keep the progress reports coming- I'm certainly interested. What sort of price do the parts you're using retail for and what language is that board programmed in- or is there some sort of interface software you can set it up via?

PS:
Here's a link to my system tj81: http://www.suzuki-forums.com/suzuki-vit ... fan-2.html

I tried to do up a table last night of components and prices but was at the missus house so it was a bit difficult. I'll try to get one rolling tonight when I get home. I'll probably end up shocking myself with the total cost as I tend to waste bits as I change my mind mid way through the process (luckily I only change the small stuff), but apart from the case, microcontroller board, and the two output boards, everything else is minor components or connectors.

The micro is an AVR so there's packages to program them in just about anything. I use Code Vision which is based on C, but a lot of people use Bascom which is a Basic type language. I prefer the C over Basic as I find it more powerful and easier to do exactly what I want. Although just about anyone can program pretty easily with Bascom.

If you keen to have a look at the micro board and out put boards:
http://www.futurlec.com.au/ATMega_Controller.jsp
http://www.futurlec.com.au/DC_Opto_Output_4.jsp
(output board drives relays but I'll put in a good description later of the functionality of everything)

I could have built the boards from scratch but for a one off project, these are just hard to beat for neatness and reliability. Only issue is that supplier takes forever and a day to deliver the goods so don't ever bother with express postage.

[murcod]

Wow! I can't believe how cheap that ATMega Controller is.

[tj81]

Thanks guys,

I have already built one of those Jaycar Voltage Switches, and unfortunately, the temperature sender in the maverick doesnt output a voltage, its only the one wire type. So i need to get a new temp sender anyway.

Ill keep looking into it.

[stuee]

Wow! I can't believe how cheap that ATMega Controller is.

Not bad. There was a slight design issue on the last one I purchased for a uni project which meant I had to de solder and raise a pin on the max232 chip, but it may have been fixed this time round. Time will tell.

Thanks guys,

I have already built one of those Jaycar Voltage Switches, and unfortunately, the temperature sender in the maverick doesnt output a voltage, its only the one wire type. So i need to get a new temp sender anyway.

Ill keep looking into it.

Try the below kit, its what I use.

http://www.jaycar.com.au/productView.as ... BCATID=347

I have the thermistor mounted to a lug that is mounted under a head bolt. Gives an indication of real engine temp and if I ever loose all my coolant I'll know about it because engine temps will shoot up and hopefully I'll be able to shut it off before blowing the engine.

My controller is going to use the same thermistor and either a second one mounted on the other side of the block or the existing instrumentation sender. I'll average out the temps between the two senders or if one gets over 10 degrees higher go off that temp.

[+dj_hansen+]

I have the thermistor mounted to a lug that is mounted under a head bolt. Gives an indication of real engine temp and if I ever loose all my coolant I'll know about it because engine temps will shoot up and hopefully I'll be able to shut it off before blowing the engine.

My controller is going to use the same thermistor and either a second one mounted on the other side of the block or the existing instrumentation sender. I'll average out the temps between the two senders or if one gets over 10 degrees higher go off that temp.

Be careful, dropping all the coolant does not neccesarily result in temp increase, i have read in a few places (albeit the interweb) that temp can actually drop when coolant is lost. Much better to make up something along the lines of these http://www.enginesaver.com.au/

I would also look at incorporating into your dual batt control temp sensors for the batteries, and maybe even setting it up like the rotronics isolators so that the charge is split to each individual battery not just 'parallaled' together through a series of relays.

I can see some excellent stuff happening here

[stuee]

I have the thermistor mounted to a lug that is mounted under a head bolt. Gives an indication of real engine temp and if I ever loose all my coolant I'll know about it because engine temps will shoot up and hopefully I'll be able to shut it off before blowing the engine.

My controller is going to use the same thermistor and either a second one mounted on the other side of the block or the existing instrumentation sender. I'll average out the temps between the two senders or if one gets over 10 degrees higher go off that temp.

Be careful, dropping all the coolant does not neccesarily result in temp increase, i have read in a few places (albeit the interweb) that temp can actually drop when coolant is lost. Much better to make up something along the lines of these http://www.enginesaver.com.au/

I would also look at incorporating into your dual batt control temp sensors for the batteries, and maybe even setting it up like the rotronics isolators so that the charge is split to each individual battery not just 'parallaled' together through a series of relays.

I can see some excellent stuff happening here

Thanks for the heads up on the coolant loss issue. The only issue i have to get around with the engine saver type sensor is that the designs I have seen involve replacing the radiator plug with plastic ones as opposed to brass (which replaced plastic ones in the rover radiators). But it would be a simple sensor to make up if I use a plastic cap.

I'm still deciding on battery management but in terms of charging like the rotronics I probably wont isolate the primary battery to charge the aux, as it needs extra hardware. I do have a spare isolator which I will be using to isolate the aux battery from any load should it get below 80% discharge. Save me spending up big on another agm. To isolate the main battery from discharging would involve a lot of rewiring so that will be getting a miss, that and now the stereo and amp are off it its very unlikely.

At the moment I would be able to monitor up to four battery voltages individually, control up to 8 outputs (3 amps each) with the output boards shown (these are what will drive any relays and solenoids). For the time being there will be three batteries used, the main starter, the aux in the rear of the cabin and a backup 9a/h under the seat to give the controller power if i loose the aux battery (I will power the board off the aux to stop any more drain from the main batt.) This leaves me one voltage sensor in reserve if I ever get a winch and want another battery up front.

Temp sensors for the batts sound interesting, I'm gonna need more a/d converters though as I have already designated all of the 8 converters the chip has available. I might look at scrapping the oil temp and pressure sensor idea and use them on batteries instead. Give me an excuse to make another box later on

Keep the iedas and suggestions coming

[+dj_hansen+]

I have the thermistor mounted to a lug that is mounted under a head bolt. Gives an indication of real engine temp and if I ever loose all my coolant I'll know about it because engine temps will shoot up and hopefully I'll be able to shut it off before blowing the engine.

My controller is going to use the same thermistor and either a second one mounted on the other side of the block or the existing instrumentation sender. I'll average out the temps between the two senders or if one gets over 10 degrees higher go off that temp.

Be careful, dropping all the coolant does not neccesarily result in temp increase, i have read in a few places (albeit the interweb) that temp can actually drop when coolant is lost. Much better to make up something along the lines of these http://www.enginesaver.com.au/

I would also look at incorporating into your dual batt control temp sensors for the batteries, and maybe even setting it up like the rotronics isolators so that the charge is split to each individual battery not just 'parallaled' together through a series of relays.

I can see some excellent stuff happening here

Thanks for the heads up on the coolant loss issue. The only issue i have to get around with the engine saver type sensor is that the designs I have seen involve replacing the radiator plug with plastic ones as opposed to brass (which replaced plastic ones in the rover radiators). But it would be a simple sensor to make up if I use a plastic cap.

I'm still deciding on battery management but in terms of charging like the rotronics I probably wont isolate the primary battery to charge the aux, as it needs extra hardware. I do have a spare isolator which I will be using to isolate the aux battery from any load should it get below 80% discharge. Save me spending up big on another agm. To isolate the main battery from discharging would involve a lot of rewiring so that will be getting a miss, that and now the stereo and amp are off it its very unlikely.

At the moment I would be able to monitor up to four battery voltages individually, control up to 8 outputs (3 amps each) with the output boards shown (these are what will drive any relays and solenoids). For the time being there will be three batteries used, the main starter, the aux in the rear of the cabin and a backup 9a/h under the seat to give the controller power if i loose the aux battery (I will power the board off the aux to stop any more drain from the main batt.) This leaves me one voltage sensor in reserve if I ever get a winch and want another battery up front.

Temp sensors for the batts sound interesting, I'm gonna need more a/d converters though as I have already designated all of the 8 converters the chip has available. I might look at scrapping the oil temp and pressure sensor idea and use them on batteries instead. Give me an excuse to make another box later on

Keep the iedas and suggestions coming

Id keep the pressure sensors, there was a post here a while back involving only invoking the aux side of the dual battery solenoid once oil pressure and volts was good (cant remember who the post was by sorry)

The idea behind the battery temp probe was to handle charging rates at higher temps, but this would have to be researched in a bit more detail, drivesafe hopefully has a few ideas here.

Are you going to include a coffee machine in there aswell?

[stuee]

Id keep the pressure sensors, there was a post here a while back involving only invoking the aux side of the dual battery solenoid once oil pressure and volts was good (cant remember who the post was by sorry)

The idea behind the battery temp probe was to handle charging rates at higher temps, but this would have to be researched in a bit more detail, drivesafe hopefully has a few ideas here.

Are you going to include a coffee machine in there aswell?

Interesting with the oil pressure and voltage. I still have a bit of research to do then

No coffee machine as I think I've just about reached the IO limit of this board

I've though of having a network of controllers that communicate to one main controller or carputer which has some form of user interface to give me stats on what each controller is doing. Aside from this one I'd like one to control on board air (because everyone needs to know precisely how many psi they have in their tank), and one I've dreamed of but involves too much work is interfacing the climate controls to bring my 97 disco up to modern standards. Way to much work fiddling with actuators and the like for me though. If I wasn't trying to save for a house though I'd happily splurge on air suspension and make my own controller for that. That would be

If I only end up using this one though there are plenty of smart touch screens (around 3" in size) that I can program to communicate through serial.

[+dj_hansen+]

This is the post i was talking about :

Danos, you can also achieve intelligent switching without electronics. Digital is all about on's and off's (1's and 0's) and this can be simulated with relays, you just need a lot if you want to get "more" intelligent.
What you can't get is true isolation as Derek's device will provide. These act in a similar fashion to a pair of one-way valves between the alternator and the two batteries, whereas a solenoid simply parallels them
Personally, I drive an old 60 series cruiser due to the fact that I like to keep things simple when in remote locations. Not much on one of them that you can't repair on the track (at least enough to get to help).
So I use a solenoid system, with a cole-hersey type battery switch to provide power to winch. Only concession towards electronics is an "on" LED in the dash.
Solenoid is switched by ignition on AND alternator good AND oil pressure good, and disconnected whenever power is put to winch via battery selector switch. This also allows for "jump-starting" from auxilliary when switch set to "both" batteries.
So car starts on main battery only. When oil-pressure is at normal running pressure and "charge" light on dash goes out batteries are connected in parallel and stay this way until alternator, oil-pressure, or ignition fail.
$40 worth of spares enables me to repair on side of road if things go pear-shaped. Even without this, a simple piece of wire can bridge out any part of the system if it fails, allowing you to at least get to assistance.

Cheap, effective, reliable, repairable, and SIMPLE.


ed

From this thread, which incidentally has a fair bit of good info http://www.outerlimits4x4.com/ftopic118274-0-asc-30.php but also a bit of banter.

And then some info on charge rate vs temp http://www.amplepower.com/primer/temp/index.html

(I'm waiting for some dvds to burn at work )

[stuee]

This is the post i was talking about :

Danos, you can also achieve intelligent switching without electronics. Digital is all about on's and off's (1's and 0's) and this can be simulated with relays, you just need a lot if you want to get "more" intelligent.
What you can't get is true isolation as Derek's device will provide. These act in a similar fashion to a pair of one-way valves between the alternator and the two batteries, whereas a solenoid simply parallels them
Personally, I drive an old 60 series cruiser due to the fact that I like to keep things simple when in remote locations. Not much on one of them that you can't repair on the track (at least enough to get to help).
So I use a solenoid system, with a cole-hersey type battery switch to provide power to winch. Only concession towards electronics is an "on" LED in the dash.
Solenoid is switched by ignition on AND alternator good AND oil pressure good, and disconnected whenever power is put to winch via battery selector switch. This also allows for "jump-starting" from auxilliary when switch set to "both" batteries.
So car starts on main battery only. When oil-pressure is at normal running pressure and "charge" light on dash goes out batteries are connected in parallel and stay this way until alternator, oil-pressure, or ignition fail.
$40 worth of spares enables me to repair on side of road if things go pear-shaped. Even without this, a simple piece of wire can bridge out any part of the system if it fails, allowing you to at least get to assistance.

Cheap, effective, reliable, repairable, and SIMPLE.


ed

From this thread, which incidentally has a fair bit of good info http://www.outerlimits4x4.com/ftopic118274-0-asc-30.php but also a bit of banter.

And then some info on charge rate vs temp http://www.amplepower.com/primer/temp/index.html

(I'm waiting for some dvds to burn at work )

I see. So effectively he's used the pre-existing instrumentation (charging light on dash) and oil pressure to control the isolator. It seems he's using the oil pressure rise as a simple timer to ensure that adequate charge has been put into the main battery before connecting the aux battery. If this is the case it wouldn't really effect what I'm planning as I'm using voltage sensing anyway.

I dont have time to read through the Temp compensation page atm though so I'll have a read tonight. As for switching smarts I will be imitating the traxide and redarc units quite closely, with my low voltage isolator for the aux being the main bonus (and building the whole contraption keeping me entertained).

[+dj_hansen+]

The ign on, alternator good and oil pressure switch is more of a fail safe incase something goes wrong, like if you leave your key switch to IGN then the battery solenoid is opened up and will allow current to drain from main to aux (until the volt cut out stop it anyway), things like that.

The beauty of building your own is you know how to fix if something goes wrong!

There are a couple of good posts/forums on CarPC setups as well that i was scanning through (for something specific; a small program written to monitor various sensor outputs from motor/ecu, but couldnt find it :( )

The bat temp vs charge rate page is the first page i found in google, but gives a good over view, so more research is probably required there.

[tj81]

I have the thermistor mounted to a lug that is mounted under a head bolt. Gives an indication of real engine temp and if I ever loose all my coolant I'll know about it because engine temps will shoot up and hopefully I'll be able to shut it off before blowing the engine.

My controller is going to use the same thermistor and either a second one mounted on the other side of the block or the existing instrumentation sender. I'll average out the temps between the two senders or if one gets over 10 degrees higher go off that temp.

Be careful, dropping all the coolant does not neccesarily result in temp increase, i have read in a few places (albeit the interweb) that temp can actually drop when coolant is lost. Much better to make up something along the lines of these http://www.enginesaver.com.au/

I would also look at incorporating into your dual batt control temp sensors for the batteries, and maybe even setting it up like the rotronics isolators so that the charge is split to each individual battery not just 'parallaled' together through a series of relays.

I can see some excellent stuff happening here

I agree, ive already got an enginesaver installed, and its worth its weight in gold. I had the small hose under the inlet manifold bust on me, and before the water level had gone below the top radiator hose, the alarm was going off, and i shut her down, absolutely fantastic.

[rapid80]

Is it possible/feasible to build the box to ip66 or 67 standards in case someone wants to mount it in the engine bay? In my case i have multiple ip66 rated circuit breaker/relay boxes in the engine bay and would want the controller box to be close by.

[stuee]

Is it possible/feasible to build the box to ip66 or 67 standards in case someone wants to mount it in the engine bay? In my case i have multiple ip66 rated circuit breaker/relay boxes in the engine bay and would want the controller box to be close by.

You start paying a lot more for ip66/67 rated kit. My relay box in the engine bay is ip65 rated and has had the hose sprayed directly at it no worries but water would probably work its way in under a pressure wash (IP66) or continuous submersion (IP67).

All the stuff I'm using for my project can be purchased at quite a reasonable price from jay car/altronics type shops. Any higher rating and you have to go to rs or farnell type places, and then the dollars start adding up because these guys typically sell to industry with deep pockets. Also you need to be more careful with cable glands and that too. In my engine bay unit I have a number of 10-15A cables coming out of one large gland which keeps them closed up nice and tight but if you wanted proper water protection you'd probably need to find a single multi-cored cable to take through the gland or use multiple glands.

So yes it would be possible but in my case the cost would be prohibitive.

[stuee]

Oh yeah, bought some new goodies last night. Need to exchange one item as its not quite what I wanted (went for a cheaper version that I thought only lacked some features but actually lacked quite a lot )



Main bit holding me up though was that i ran out of pcb terminal mounts so I picked some more of them up. I thought while I was there I would pick up the rest of the bits to finish the dual batter installation (distribution blocks and dual 60amp circuit breaker) and the new thermo fan relay arrangement (dual pole relay and two 30amp cb's).

I've got a bit more spare time tonight so hopefully I'll just about finish off the pcb for my controller and test all the inputs. After that the next step is programming which involves a fair amount of testing and debugging.

When the pcb is done I'll post up some photos showing the different components and what they're for.

I've had a look into the temperature compensation and it doesn't seem to be of use in my instance. Basically the charge voltage is reduced as temperature increases. Temperature compensation would be possible to achieve but it would involve tapping into the regulator on the alternator and as my alternator only puts out around 14.1-14.4 volts it doesn't seem to be much of an issue. Temperature compensation looks to be really beneficial for rapid charging with voltages over 15.5V where it is ramped down as the temp increases, resulting in a very fast charge and supposedly long battery life.

In my case the best I could do I suppose is stop the charge if temp got too high. I don't really fancy pulling apart my alternator to send it false voltage signals to manipulate output voltage, though I don't see why this wouldn't be possible. It may present problems using the different types of batteries though, unless I fully isolated each battery as it charged and had voltage/temp maps for each battery. Now that would be getting complicated but very

[stuee]

Well I've done a bit more work. I've finished the input board.





Also got my programmer box working again so i can start writing the program for the mirco controller. I've got a test adc board and digital input board so i don't have to actually have inputs from the car to test that my box is working.

[stuee]

SHITSHITSHIT

I just blew up my microcontroller after inadvertently placing the adaptor for my programmer on some steel pliers.

To say I'm pissed is an understatement. Serves me right for rushing and working in a messy environment I suppose. Pisses me off big time though.

$40 wasted and with the time it takes the supplier I'll be waiting another 3 weeks. Im so close to just ordering a traxide system for the time being.

It shits me even more because I was so close to finishing it! (literally was going to test it in the car this weekend).

[CanberraMav]

tj81 wrote:

Ive been looking for a digital temperature display with fan controller for ages, and the best i could find was this one:

http://cgi.ebay.com.au/JAW-IZUMA-Water- ... 7C294%3A50

There's also a similar one.

What i want it to do, is control a set of AU Falcon thermo fans, and be able to set the hysteresis to what i want for each fan. The ones above a ok for a single fan, or running 2 fans at the same time with the same temps etc, but id like to be able to set one fan to come on with normal operating temp, and the other when the need arises, and or the air con is turned on.

Autobarn sell a digital temp controller which also monitors voltage. Not sure if it is capable of running fans independantly though. Might be worth having a look.

[its aford not a nissan]

Here is a link to the relay wiring that I will be using (thanks once again to murcod). Still relies on two separate signals but operates as two speeds instead of two fans.

http://users.on.net/~murcod/XL-7/Thermo ... wiring.JPG

ok , i wired up a pair of falcon thermo fans as per the above diagram , but for the life of me i cant work out why oh why the fans are running independant of each other ie: at low temp , only one fan starts at full speed , then at high temp then the other fan starts at full speed , not the expected both fans at 1/2 speed at low temp , i will run the multimeter over it tomorrow to see where the power is going , but it seems the power is going strait through the first fan and not spinning it ???

[chimpboy]

Did you definitely get a double-throw relay rather than one of the 5-pin relays that are really just four-pin relays with a spare output?

I don't like one of the failure modes of that diagram!

[its aford not a nissan]

yep im pretty sure , well 87 and 87a have no continuity between them , and 87a and 30 had continuity when un energized

what is the failure mode you speak of ??

[chimpboy]

edit: sorry, I'm wrong, I was tired

[its aford not a nissan]

If the third relay gets stuck "on", then you can dead short to the battery with the changeover relay.

I think there is a more failsafe version, let me have a stab at it.

are you sure it would short out ??? power from the change over relay is always seperate from that part of the circut

actually what it would do is what is happening to mine at the moment , ill check tomorrow to see if i stupidly put the earth for the 3rd relay on the other 87 pin and not the 30 pin , its a hard mistake to do though as the pins are in different directions


haha you didnt edit fast enough

[its aford not a nissan]

all sorted , had the power wires to the fans mixed up

i also modded the shrowd to go all the way to the bottom of the radiator and hooked up the a/c to the low temp switch

now all i need is to test it out

[murcod]

If the third relay gets stuck "on", then you can dead short to the battery with the changeover relay.

I think there is a more failsafe version, let me have a stab at it.

are you sure it would short out ??? power from the change over relay is always seperate from that part of the circut

actually what it would do is what is happening to mine at the moment , ill check tomorrow to see if i stupidly put the earth for the 3rd relay on the other 87 pin and not the 30 pin , its a hard mistake to do though as the pins are in different directions


haha you didnt edit fast enough

I can't be bothered to check if that actually could occur, but that is why you put fuses in all electrical circuits. If something goes wrong the fuse blows and no harm is done.