# Charging - is it any more complicated than this?



## Evan (Feb 20, 2008)

That hardware looks right. The algorithm you are proposing is not my favorite though. I will have to mull that part over. I would replicate the top dc/dc converter again to make the 5V PSU just to lower the part count. Nice idea though.


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## SimonRafferty (Apr 13, 2009)

I found a little more info - specific to Optima's - but may apply to others as well. http://www.geocities.com/CapeCanaveral/Lab/4429/optima.htm#HowOptimasuggest

Essentially, it says:


> Constant voltage: 14.7 to 15.0 volts temperature < 50C, no current limits, continue until current falls below 1 amp, then finish with 2 amp constant current for 2 hours.


In my case, I would have to limit the max current to 10A.

It also mentions a charge management chip - that as far as I can see has been replaced by this: http://focus.ti.com/lit/ds/symlink/bq24450.pdf
It contains everything you need to control an intelligent SLA charger with the addition of a few components. However, it is using the control transistor as a variable resistor rather than using PWM in a Buck config as above - so it's probably not that efficient.



> I would replicate the top dc/dc converter again to make the 5V PSU just to lower the part count.


If it were commercial - that would be an excellent idea.
It also occurred to me that the charger would double as a DCDC converter with a slight software change.

Si


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## Jimdear2 (Oct 12, 2008)

Si,

Here is a direct quote from a Power Sonic 75ah 12volt AGM battery spec sheet, this is similar to the Hawker Oddissy and High Rates I use in my tractors.

"Cycle Applications: ​​​​Limit initial current to 22.5A. Charge until battery voltage (under charge) reaches 14.4 to 14.7 volts at 68°F (20°C). Hold at 14.4 to 14.7 volts until current drops to under 750mA. Battery is fully charged under these conditions, and charger should be disconnected or switched to “float” voltage.​

“Float” or “Stand-By” Service: ​​Hold battery across constant voltage source of 13.5 to 13.8 volts continuously. When held at this voltage, the battery will seek its own current level and maintain itself in a fully charged condition."​

Although it doesn't mention it here I have heard of those voltage spikes before and thought they might be used to clear up / prevent sulfation.

I will follow the build of your battery charger with great interest. because it looks like it is exactly what I have been looking for. And at a price I can afford. 

I scrounge the parts and I build it.

I have a lot of AGM batteries and a lot of 12 volt AGM battery chargers. It gets to be a hassle hauling all of these chargers around at the tracks. I dream of a single charger with the correct profile with a set of balancers so I can just plug in and walk away.


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## SimonRafferty (Apr 13, 2009)

That's great. All I can find on the pulse charging is that it helps desulphication (sp?) - there does not seem to be much info on the duration, duty cycle, current or voltage of the pulses though.

I have figured on writing the code for the microcontroller in a format that is easy to modify so people can design their own charge profiles. The microcontroller I'm proposing to use is available built up on a board - you just need to plug it in to a PC and upload the program. I'll post details here as they emerge.

What about (for completeness) profiles for flooded cells, NiMH, Lithium etc? Could one charger do the lot with just a change of software?

Si


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## Jimdear2 (Oct 12, 2008)

SimonRafferty said:


> That's great. All I can find on the pulse charging is that it helps desulphication (sp?) - there does not seem to be much info on the duration, duty cycle, current or voltage of the pulses though.
> 
> I have figured on writing the code for the microcontroller in a format that is easy to modify so people can design their own charge profiles. The microcontroller I'm proposing to use is available built up on a board - you just need to plug it in to a PC and upload the program. I'll post details here as they emerge.
> 
> ...


Si,

It sounds like you may have had "The Idea" that will help a lot of people who are willing to put some effort, time and thought into what IMHO is often left to last and left to other (expensive) "EXPERTS".

Filling the tank so to speak.

I'm sure that this proposed charger is similar to those transformerless chargers like the pile of small 12 amp Schumaker Speed Chargers I have and haul around, but it sounds like it will be a lot more powerfull and versitile. Plus the fact it will in most cases not be built to a bean counters specifications. We all know we get what we pay for.

I think that all of us that have an interest in this should shop around the battery manufacturers sites and send you as many charging profiles as can be found, for as many different batteries types as possible. 

I would be willing to organize and catalog any collection you might aquire if you need any help.

This collection of profiles being done for two reasons.

One; to give you an overview, so when you write your basic code there is enough room to take on some difficult profiles.

Two; to create a library of profiles that can be placed on a WIKI.

Last; if you need a clumsy amature EV builder to try putting together a charger from a schematic and parts list "I'm your guy". If some electronic component has smoke inside to be let out, I always find a way.

If I can build it, anyone can.


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## etischer (Jun 16, 2008)

If you decide to use an isolation transformer, you may consider one that has 115v and 230v taps so you can run dual voltage. The transformer would also help reduce noise and harmonics on the incomming AC line. You could also step the voltage up a bit higher. Most AC powered evs are probably running 25-26 12v batteries. If you can get the voltage up to 360v, that would be much more useful. 
' 
You may also need filtering on the current transducer. The current will be switching at high frequency (probably around 3khz). You may not get an accurate reading of the current if your A to D converter is only sampling a few times a second. 

Looks good amigo


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## SimonRafferty (Apr 13, 2009)

etischer said:


> If you decide to use an isolation transformer, you may consider one that has 115v and 230v taps so you can run dual voltage.


Good idea - since these are available off the shelf they would be easy for anybody to add as necessary.

The capacitors on the mains DC side of the IGBT should smooth out a lot of the ripple on the mains side.



etischer said:


> You may also need filtering on the current transducer.


Very true

Si


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## etischer (Jun 16, 2008)

You might also want a precharge circuit unless the charger will be permanently connected to the batteries.


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## Amberwolf (May 29, 2009)

Not sure how well it might work, but what if, as the controller for the system, you took one of the single-cell lead-acid charger chips that already has one or more charging profiles built in, and simply used it's scaled output to control the IGBT switching system?

Scale the feedback from the charging system's voltage and current monitors, etc, so that it is within what it would have been for a single cell, so that the chip is monitoring and charging as if it were only hooked to a single cell.

Does that description make sense?

There are a number of them out there already:
http://www.google.com/search?q=lead+acid+charge+ic

The UC3906 and BQ2031 are a couple of the ones I'd looked at to do something like this for my ebike system with 3 12V SLAs, but haven't gotten back to the project in a while due to too many pans on the fire. 

I'd started out with the idea that I'd simply put a separate BQ2031-based charger on each battery, kind of like it's own BMS built-in, but wanted to find a way to reduce weight and parts count, since these chargers would stay as part of the ebike so I could always plug in for opportunity charging. Thus, the one-scaled-to-three approach, which I still need to investigate and test.
________
Vaporizerinfo.com


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## SimonRafferty (Apr 13, 2009)

Upscaling a 12v charger was where I started from - there are a couple of posts from me on this forum about exactly that. However, to upscale it, you are in effect building the above circuit and using someone elses chip to control it. 

Also, most of these chips use the transistor as a variable resistor to limit the current. That just wastes a large proportion of the energy as heat. Pulse Width Modulation is much more efficient (that's why we don't use big rheostats as speed controllers any more!) and for a given current you can use a much smaller (cheaper) transistor.

Using a microcontroller just made more sense to me because each user can tune the same design to whatever voltage, current and profile they like. The difference then between a 48v SLA and a 220v Flooded charger is just a few lines of code.

Si


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## Jimdear2 (Oct 12, 2008)

SimonRafferty said:


> Upscaling a 12v charger was where I started from - there are a couple of posts from me on this forum about exactly that. However, to upscale it, you are in effect building the above circuit and using someone elses chip to control it.
> 
> Also, most of these chips use the transistor as a variable resistor to limit the current. That just wastes a large proportion of the energy as heat. Pulse Width Modulation is much more efficient (that's why we don't use big rheostats as speed controllers any more!) and for a given current you can use a much smaller (cheaper) transistor.
> 
> ...


Si,

Have you gone any further with this. 

I am not very well trained on electronics and never was any good at programming, I couldn't design what you have here. But I'll tell you, I can recoginize what appears to be a great idea.

I'm still willing to be a try out tester.


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## SimonRafferty (Apr 13, 2009)

I am going to build it, based on something like a basic atom microcontroller (which has analog inputs and is easy to program in BASIC).

I've collected together all the parts - so it's just a case of finding some time! At the moment, while the weather here is good, I'm building the truck that it is going to charge - but the next spell of rain and I'll be soldering!

I'll prove whether the concept works then publish a final design and program here that anyone else can pick up and play with.

Si


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## Jimdear2 (Oct 12, 2008)

SimonRafferty said:


> I am going to build it, based on something like a basic atom microcontroller (which has analog inputs and is easy to program in BASIC).
> 
> I've collected together all the parts - so it's just a case of finding some time! At the moment, while the weather here is good, I'm building the truck that it is going to charge - but the next spell of rain and I'll be soldering!
> 
> ...


Wonderful, I'll wait patiently (at least I'll try).

Any chance you could publish a list of needed components so I can start scrounging.

Have a great day,


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## SimonRafferty (Apr 13, 2009)

Jimdear2 said:


> Wonderful, I'll wait patiently (at least I'll try).
> Any chance you could publish a list of needed components so I can start scrounging.


Probably best to see what works first! All the parts I'm planning on using have come from a bust computer UPS save for the computer.

Si


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## jyanof (Nov 11, 2008)

if you're interested, i've done the OP's circuit using a low side mosfet instead of the high side IGBT. I'm using an atmega16 for the micro.

i'm still in development, but so far have tested it using a pot to control PWM and hit my goals of charging my 144v pack at 20A. Currently, (no pun intended), i'm developing the current control algorithm and just ordered IC's for isolated pack voltage measurement.

some lessons learned:
- keep the diode, switching device, and input caps very close to minimize stray inductance and high voltage spikes
- my original mosfet's back was electrically connected to the drain pin - this caused high voltage spikes when it wasn't isolated from the heatsink. I went to an isotop mosfet configuration to still have good heat dissipation and electrical isolation.
- cheap caps have poor ripple current capability and heat up very quickly. my last 20A test had the mosfet/diode operating 10C above ambient while the caps were 30C above ambient.

hope that helps, i'm having a ton of fun with this project - I'm sure you will too!

here's the ecomodder thread i've been posting to if you're interested...
http://ecomodder.com/forum/showthread.php/diy-open-source-ev-charger-6795-14.html


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## dimitri (May 16, 2008)

jyanof,

awesome project! So what is the estimated total cost in parts, assuming good caps that won't blow up in few months of daily use?

I'm really interested to play with this for LiFePo4 charging....

thanks


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## jyanof (Nov 11, 2008)

dimitri said:


> jyanof,
> 
> awesome project! So what is the estimated total cost in parts, assuming good caps that won't blow up in few months of daily use?
> 
> ...


I haven't done a total cost rollup recently, but here's my estimate:
power components - 125
control components - 75
various heatsinks/fans/connectors/other hardware - 100

it's amazing how fast all the little things add up, but I think it can be done for ~300 bucks. Of course, this is for a 20A 144V charger - it'll be a little cheaper if you're going lower voltage or lower amps.

Another future goal would be to make a PFC stage to allow the charger to operate near the outlet rating, but that's farther away and would add more cost.


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## dimitri (May 16, 2008)

Nice, that's $700 less than my Zivan which also does 20Amps output at 120-144 Volts. 

I am too scared to do DIY motor controller, but charger seems to be within my skill set, so I am watching with interest.

In addition to watching the pack voltage, I would use one of atmega's inputs for BMS HVC signal. When first cell reaches HVC it would signal the charger to drop the current and start balancing stage. Then, when pack voltage catches up to max voltage we are done.

Thanks


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## Amberwolf (May 29, 2009)

When picking caps for anything like this, be it a switching power supply, PWM controller, etc, use the large format cans with radial leads out of only one end, and make sure they are the large formed type--not just the little round wire leads. 

The formed type usually looks like any of these:
http://www.pittjug.org/b2b/pics/Electrolytic_Capacitor.jpg
http://www.allproducts.com/ee/lingin/01-electrolytic_capacitor-l.jpg

instead of these:
http://reprap.org/pub/Main/ElectrolyticCapacitor/electrolytic-capacitor.jpg

The first two in this pic:
http://img.alibaba.com/photo/12238928/Panasonic_Electrolytic_Capacitor.jpg
are formed, the others are standard wire leads.

The formed ones can carry higher currents with less heating.
________
Avandia lawsuit


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## SimonRafferty (Apr 13, 2009)

jyanof said:


> if you're interested, i've done the OP's circuit using a low side mosfet instead of the high side IGBT. I'm using an atmega16 for the micro.


Great info! 
I had decided it didn't make too much difference whether it was low or high side with an opto driver. Currently I'm using a mobile phone charger for to supply the high side driver (as it has to be isolated) and is something that everyone has a stack of. Likewise, the microcontroller is powered by another phone supply.

All the capacitors and diodes have been salvaged from junk computer UPS's and switch mode PSU's, as has the IGBT. The only real cost so far has been the microcontroller.

Si


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## SimonRafferty (Apr 13, 2009)

Jyanof, I was interested to read on your blog about you using an AVR microcontroller. I was originally going to use a Basic Atom - but these look much better! I have ordered one of these:








https://www.sparkfun.com/commerce/product_info.php?products_id=37

As the control interface. They are about $65 delivered which doesn't seem too bad as it's already built up and ready to go. It should just need plugging in to the charger and a bit of coding to make it fly.

I hope to write a user interface which will allow me to alter the pack voltage and charge profile parameters from the LCD using only the five buttons.

Si


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## Wirecutter (Jul 26, 2007)

Jimdear2 said:


> I'm sure that this proposed charger is similar to those transformerless chargers like the pile of small 12 amp Schumaker Speed Chargers I have and haul around, but it sounds like it will be a lot more powerfull and versitile.


Ha ha! So I'm not the only poor slob dragging a bunch of 12v chargers around!  

In my case, I've persisted because I haven't come across a decent (i.e. functional & affordable) charging/balancing setup that would allow me to simply have one charger. Oh, and did I mention cheap? Most of those fancy chargers cost a lot more than having a cheap Schumaker for each cell.

I know which end of the soldering iron is the hot part, so if I find a circuit I like, I'll build it (and post results here, of course.)


-M


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## SimonRafferty (Apr 13, 2009)

I was totally with you on that originally - I bought 10 low cost 'intelligent' chargers on ebay. Of those 6 worked perfectly, one let the smoke out after 10 mins, 2 were completely dead from the start and the last cooked the battery to the point of the casing melting!

Obviously it was a bad choice of charger (Chinese rubbish) but it determined me to build my own. At least then if it doesn't work, I can fix it!

Si


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## SimonRafferty (Apr 13, 2009)

Good news!

I've built the elcectrickery bit of this and it works pretty good!

I admit I had to buy a couple of parts despite wanting to build the whole thing out of salvaged junk - but I've spent less than $10 (apart from the $60 microcontroller board).

I've used an A3120 Optical high side IGBT driver - for simplicity more than anything as well as an LTS 25-NP hall effect current sensor which spits out a voltage proportional to the current passing through it.

At the moment, I have the circuit above being fed through a Variac (variable ratio transformer) with about 50v AC. The IGBT is being fed with a 25% duty cycle PWM (generated by a 555 oscilator chip) at about 20khz and have the output connected to a small SLA battery. This just provides a relatively safe combination of voltage and current.

I'm using an old Dell computer PSU to supply the 15v required for the IGBT driver plus a Nokia mobile charger for the 5v to drive the computer and Current sensor.

The battery is sinking about 1A at 14v - which is about right. Nothing seems to be getting hot - which is a good sign.

The next step is have the PWM controlled by the computer. I would have started this evening but the damn RS232 lead seems to have vanished! I'm enjoying a bottle of beer to see if it stimulates my memory

Si


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## jyanof (Nov 11, 2008)

SimonRafferty said:


> Good news!
> 
> I've built the elcectrickery bit of this and it works pretty good!


Congrats! A power section that works is the first step! I don't know how IGBT's work, but apparently mosfets dissipate more heat due to switching at higher voltages. I recall a motor controller thread on this site that mentioned the same thing for IGBT's. I found out the hard way when the system worked for a 120V input and a 12V battery but didn't work for 240V input and a 144V pack. A loud pop and black soot all over the components resulted.


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## SimonRafferty (Apr 13, 2009)

I'm under the impression that the heating is a function of the current flowing and the effective resistance of the device. As you transition from off to on (or vice versa) there will be a period where the resistance is falling from 'infinity' to 'zero' and it is in that phase that the heating largely takes place.

The faster you switch, the more time you spend transitioning and heating the devices. So, you have to make sure the transition time is as brief as possible and you do not operate at a higher frequency than you have to.

Higher voltage (or at least a higher differential voltage across the device) will push more current through a given resistance and so result in more heating.

However, since I am monitoring the current flowing through the device - I can limit the average current to within a safe limit for the IGBT 

Si


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## jyanof (Nov 11, 2008)

SimonRafferty said:


> I'm under the impression that the heating is a function of the current flowing and the effective resistance of the device. As you transition from off to on (or vice versa) there will be a period where the resistance is falling from 'infinity' to 'zero' and it is in that phase that the heating largely takes place.



Yeah, I guess I couldn't find anything for IGBTs that relate switching losses to voltage other than this post:

http://www.diyelectriccar.com/forums/showpost.php?p=127347&postcount=194

And I don't know if they actually tested to find that out...

But it is true for mosfets - switching losses increase with increasing drain-source voltage. 

All of this digging into IGBTs is making me reconsider them...


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## SimonRafferty (Apr 13, 2009)

Bit of an update!
I had a bit of a hold-up when my scope stopped working. However, I've always wanted a Fluke Scope-meter - and this was a good excuse! eBay delivered me a 20MHz scopemeter for £205 - which has turned out to be a total bargain - I love it! It couldn't be easier to use.

In the mean time I've been writing the software for the above microcontroller. The application has become quite big (in microcontroller terms) but has been written to be as generic as possible so other people can use it with other hardware.

It uses one ADC converter to measure voltage and another for current - and calibrate these in software to readings taken with a meter - so thereafter it knows what it's doing.

A charge profile is configured in six phases. In each phase you set the desired maximum current and voltage (neither will be exceeded). You then set criteria to allow it to move on to the next phase. These are a voltage, a current and a timeout. If the measured voltage exceeds the voltage or the current drops below - that charge phase ends and the next begins.

There is also an enable setting so you can use between one and six phases in the profile. One of them (number 3) is configured as a pulse charge where it charges for 1 sec then rests for 100ms - but it's use is optional.

All the settings are blown in to EEPROM so it only needs configuring once.


This evening, for the first time, I connected it all up - and it worked perfectly! I was charging a 12v SLA at 14.7v, 2.5A derived from a 60v peak to peak AC supply (I'm using a Variac (variable ratio transformer) for the AC supply.

I tried a few different PWM frequencies - and it all seems happiest at about 30khz with nothing getting particularly hot, no nasty transient spikes and nice stable readings on the ADC's.

I used an old transformer for the inductor in the battery feed and a pair of 220uF 200v capacitors on the input from the transformer. These will need upgrading for operation on 230v.

If any of you want the assembler (or hex) for the uController - PM me your mail address and it's yours!

I'll post some piccies later in the week!

Si


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## SimonRafferty (Apr 13, 2009)

I had a bit of a mishap! One of the power supplies I was using didn't appreciate supplying 1A for over an hour. The regulator failed such that it delivered 28v to the microcontroller and current sensor - toasting both!

Just waiting for a new controller to arrive from the US before it progresses any further.

In the seconds before it blew - I had it working really nicely. I found this site:
http://www.scribd.com/doc/6834939/Buck-converter-design

which explained a little more about buck converters and allowed me to reduce the ripple on the output from 1v to 10mv (by using better quality, faster switching diodes (also from a UPS). I also reduced the PWM switching speed from 35kHz to 7kHz. Although you can hear it whistle a little while charging, it reduces the supply current required for the high side driver from 1A to 10mA and the IGBT lets a lot less hot.

I took the supply voltage up to the max my variac will spit out (260v AC giving 370v DC out of the bridge rectifier) and it still worked perfectly charging a single 12v battery at 14.6v.

Once it is charging a 180v string using 230v AC it will be doing a lot less work so should still work just as well (fingers crossed).

Si


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## Jimdear2 (Oct 12, 2008)

Si,

Glad to see your wonder charger is progressing. I have put off remounting the six Schumacher 12 volt chargers I use to charge the AGMs in my pulling tractors until we see the result of your design. 

I would much rather eBay the six and use the proceeds to purchase the components to reproduce your charger. 

The tractor pulling season is almost over so I can hopefully pile all of the chargers in a corner until your design is finalized.

Is there anything I can do from this side of the pond to help you. As I said previously I would be more then willing to act as a beta builder. 

Slightly off topic but how is the land Rover going I haven't seen anything about it but that could be my fault.

Have a great day


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## SimonRafferty (Apr 13, 2009)

Thanks Jim - May well take you up on that!

The Land Rover is finished and running. The stumbling block has been getting insurance. The Insurance company are fine about it but wanted a third party engineers report writing - but the company they recommended turned out to be idiots! "I see it's an electric car - does that mean it has batteries in it" was one of their quotes.

I now have a report from them - but may need to get another one produced as this one is full of inaccuracies including the number and location of batteries and the resulting effect on weight distribution.

The insurance company says it is a legal document so must be accurate. We'll see what the underwriters make of the report!

Si


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## Jimdear2 (Oct 12, 2008)

SimonRafferty said:


> Thanks Jim - May well take you up on that!


Si,

Are you refering yo the PM I sent? I hope so.



SimonRafferty said:


> The Land Rover is finished and running. The stumbling block has been getting insurance. The Insurance company are fine about it but wanted a third party engineers report writing - but the company they recommended turned out to be idiots! "I see it's an electric car - does that mean it has batteries in it" was one of their quotes.
> 
> I now have a report from them - but may need to get another one produced as this one is full of inaccuracies including the number and location of batteries and the resulting effect on weight distribution.
> 
> ...


Bureaucrats . . . Don't you just love them, can't do anything without a ream of paperwork to cover their @$$. And I suppose these useless reports are at your expense?

Hope you "get er dun" soon.

Be well,


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## SimonRafferty (Apr 13, 2009)

Quick update.
I now have a version of the hardware and software that works OK. I dumped the hall effect current sensor in favor of a simple 0.25 ohm shunt. At least there is a simple linear relationship between current and voltage read by the ADC - it is a lot cheaper too!

This evening I built the thing on to stripboard and mounted all the bits that get hot on a chunk of heatsink I found. After a bit more testing I'll give it a whirl.

The whole thing is remarkably simple compared to other chargers I've seen - I guess most of the work is being done in software. The only bit of electronics I had to build fits on 2.5" square of stripboard and took 20mins to solder together.

For anyone else building one of these, I think they are going to need a scope. Each different combination of components I tried needed different values of inductor and capacitor to reduce the ripple on the output.

I'll post up some piccies soon!


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## SimonRafferty (Apr 13, 2009)

Something to watch out for!

I have built the charger, put it in a box - and connected it up to the mains. I had a bleed resistor across the big capacitor so it would self discharge once the mains was disconnected (it stored enough charge over a weekend to give me a decent shock on the monday - that's something to watch out for as well!).

I used a 1W metal film resistor (100k). I noticed it was getting a bit hot - and then suddenly it failed. What surprised me was that it failed short circuit! Shorting the capacitor (charged to 360v) made quite a pop!

Unfortunately, in doing so it seems to have fried the bridge rectifier, 3 25A fuses, the IGBT Driver and the IGBT - surprisingly. I was using an inductor on the mains input to block RF. I'm wondering if the short built up enough stored energy in this to generate an IGBT killing spike?

It's a bummer that a 5p component can do so much damage! Up until the failure, it seemed to be working OK though. It was pushing 19A at 190v = 3.6Kw.

Although it's fairly neat - it does weigh about the same as my Variac (which is only 10A). I posted an idea on here to use the computer to control a variac via a servo which achieves largely the same as the above but with no difficult electronics. The main objection to it seemed to be weight. I don't think - at least for 10A - there is going to be much in it.

I like the servo-variac idea because it's almost mechanical - you can see what it's doing and how it works and only need to be able to wield a hammer to make one!

Si


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## Amberwolf (May 29, 2009)

FWIW, on all the switching supplies I've cannibalized, the cap-drain resistor is in the several-megohm range, minimum. EDIT: and it's usually a fairly small resistor; many are 1/2 watt, a few of the very high resistance types are 1/4 watt.
________
BESTHERE


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## SimonRafferty (Apr 13, 2009)

1 Meg seems to stay cool! I thought it was all over - as I had blown to only IGBT module I had - but I found another one this evening.

Assembled it all and it works perfectly. I've tested it up to 35A at 200v at which the bridge rectifier and Shottky diode were getting kind of hot.

I'm currently charging my batteries at 8A just to be on the safe side.

All in, it works very well. To build it without using parts from junk UPS's will cost about $200 - but obviously less if you can cannibalize other kit.

I'm going to post up the full design with photos and a parts list tomorrow as a new thread. This thread was really about discussing the possibility - the actuality deserves it's own.

I hope that other people will try it and feed back changes to the hardware and software. 

Si


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## Jimdear2 (Oct 12, 2008)

Si,

Thank you for not giving up. For a while I thought that after the first rig you built went bad you might let it go.

I had resigned myself to fussing with six 12 volt and one 48 volt chargers or spending big bucks for a single charger for the two tractors.

Now that I have started looking at a 13 inch GE with 164 + volts for a new 1850 pound tractor I feel more comfortable knowing that there will be a single charger that can do each of the tractors or keep the dump charge pack charged up in between charging the tractors.

I just bought a 240 volt 40 amp generator (2 20 amp 110 volt circuitts) so I should be able to keep things topped up next pulling season.

I will be waiting to download your specs and diagrams. I'll have my brother who is an EE with one of the defense contractors and my pulling partner (also an EE) start scrounging through their collections for parts as soon as I get them.

The pulling season ended this last weekend so as soon as I fix a couple of minor things and winterize them, I'll need a good winter project.

Again Thanks,
Jim


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## Amberwolf (May 29, 2009)

SimonRafferty said:


> I'm going to post up the full design with photos and a parts list tomorrow as a new thread. This thread was really about discussing the possibility - the actuality deserves it's own.
> 
> I hope that other people will try it and feed back changes to the hardware and software.


Once I see what's needed for it, and scrounge up the other parts, I'll see about buildng an MCU programmer adapter (should be easy thru serial port?). I'm sure I already have all the other parts except that and an actual MCU for it. 

If the code can be adapted to the STM32 or STM8 then I can use the ones in my dev kits (preferably the STM8, since I have two and they're already USB sticks). Then I can just cut traces and handwire out to the charger's electronics. 

For a display, I have a couple of parallel-input 16x2 vacuum fluorescent displays off of rackmount server cases, if needed. Probably even have some LCD ones in old printers and stuff (I know there's one in my HP LJ on the network, but I would need to make it so I could put it back in if something goes wrong with the printer to read it's error messages, if it won't talk over the network--if it still talks, all the LCD messages are readable on it's setup page in a browser). 

I have several UPS boards around, including one from an APS SmartUPS2200, and all their transformers and whatnot. 

I'll only be charging (at first) 36V of batteries, but later will probably do 48V.
________
Bongs


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## PaulC (Jan 19, 2012)

Hi Simon
as i am new to this idea (Battery charger >10A @ 12v for 100A Car Battery)
This project seems to be an excellent one, even though it was a while ago, would it be possible to see the follow up you have done.
The Code both written & assembled would be a great help in this learning curve.
also if there is a circuit diagram would be great..
I am looking forward to doing this charger myself.

Link :
http://www.diyelectriccar.com/forum...-any-more-complicated-than-thisi-32967p4.html



SimonRafferty said:


> 1 Meg seems to stay cool! I thought it was all over - as I had blown to only IGBT module I had - but I found another one this evening.
> 
> Assembled it all and it works perfectly. I've tested it up to 35A at 200v at which the bridge rectifier and Shottky diode were getting kind of hot.
> 
> ...


Many thanks
Paul


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## SimonRafferty (Apr 13, 2009)

It spawned this thread:
http://www.diyelectriccar.com/forum...build-your-own-intelligent-charger-36627.html

Si


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## PaulC (Jan 19, 2012)

Excellent
now i can follow it on


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