Battery Monitors

[Evo]

I think you need to read the thread again.

 

Everything you've just said has been covered. All of it

 

 

It definately has allready been covered..!!! datalogging and downloading to a PC has been covered a million times over everywhere you look. I Just thought I would point out some other companies that have been doing it for years and might give you some pointers/advice.

 

Took the hump again have we..???

[BEngo]

I'm pondering how to get a device to act as a DHCP server one minute (for when someone plugs a PC into it) but be a client the next minute (for when someone plugs it into another DHCP server such as a router). I have no idea how this would work.

 

As for ethernet processing that's not really an issue. MIPS or ARM is totally unnecessary and as for Linux. Forget it. I've done one device with embedded Linux. Never again. Utter rubbish. Could have got it running quicker if I'd written the entire thing myself in machine code!

 

 

Apart from the functions can you ensure it comes with some mounting options for the modules, the processor and the display, so that a retro-fit is made easier?

 

Back boxes, panel mounts, DIN rails, 19 inch racks, big pads designed for glue or sticky tape, IP66 enclosures etc. spring to mind for starters?

 

And have a very careful think about the general form and footprint of the units so that they are easy to find space for in a typical engine or battery space. Big and thin probably wouldn't work, nor would something sticks out a long way, but whatever, mounting direction and positioning of the connectors needs to be thought out and if possible versatile.

 

Don't forget either easily shortened extended or modular lengths of interconnecting cable which can be ordered with a unit.

 

N

[WotEver]

I'm pondering how to get a device to act as a DHCP server one minute (for when someone plugs a PC into it) but be a client the next minute (for when someone plugs it into another DHCP server such as a router). I have no idea how this would work.

Does this make sense? From a simple block-diagram perspective, if the device sees an ethernet connection established and doesn't receive a DHCPDiscover message after x seconds then it sends one itself. If it receives a DHCPOffer back then it accepts that it's connected to a router and acts as a client.

 

Basically gleaned from here: http://publib.boulder.ibm.com/infocenter/iseries/v5r3/index.jsp?topic=%2Frzakg%2Frzakgconceptinteract.htm

 

Tony

[MoominPapa]

I'm pondering how to get a device to act as a DHCP server one minute (for when someone plugs a PC into it) but be a client the next minute (for when someone plugs it into another DHCP server such as a router). I have no idea how this would work.

 

The simplest way is make the mode (client/server) a configuration option, but if you want it to be automatic you can do something like this:

 

At start-up, broadcast DHCPDISCOVER packets and wait for a response from a DHCP server "out there". If you see a DHCPOFFER, go through the DHCPREQUEST/DHCPACK handshake, get an IP address and you're done 'till the lease expires when you renew. If, on the other hand you never see a DHCPOFFER, after a timeout go into "network master" mode. Configure the local interface with a static address (like 192.168.0.201) and start a DHCP server that listens for DHCPDISCOVER broadcasts from other hosts on the network.

 

As for ethernet processing that's not really an issue. MIPS or ARM is totally unnecessary and as for Linux. Forget it. I've done one device with embedded Linux. Never again. Utter rubbish. Could have got it running quicker if I'd written the entire thing myself in machine code!

You could save yourself a lot of hassle by avoiding TCP. I'm considering a protocol where the state of the monitor is represented by one or more frames, each of which fits into a single, minimum size UDP packet. the monitor listens for UDP packets which form requests and replies with UDP packets containing frames of current state. Now you're down to implementing an ethernet hardware driver, ARP, maybe DHCP, and a routine to decorate frames with UDP and ethernet headers. That sounds like it would be doable in bare microcontroller hardware.

 

MP.

 

Edited to add: WotEver beat me to the same solution.

Edited again: No he didn't, his is backwards. Acting as a client first is better than passively listening for other DHCP clients.

Edited December 1, 2010 by MoominPapa

[WotEver]

Edited to add: WotEver beat me to the same solution.

Except I defaulted to a router and you defaulted to a client

 

Tony

[MoominPapa]

Except I defaulted to a router and you defaulted to a client

I spotted that when I thought about it.

 

MP.

[Gibbo]

It definately has allready been covered..!!! datalogging and downloading to a PC has been covered a million times over everywhere you look. I Just thought I would point out some other companies that have been doing it for years and might give you some pointers/advice.

 

Took the hump again have we..???

 

Like I said, you need to read the thread.

 

You wrote:-

 

I read remote as being 100miles away or even thousands of miles away. I didn't read it as sitting 20 yds up the boat or outside in the car with the laptop plugged in the fag lighter and a twisted pair cable hanging out the window.

 

And yet earlier I wrote:-

 

But some people still want to do that. This way they can by sorting their own internet crap on the boat and plugging this into it via industry standard ethernet. Therefore they can still do it but the device doesn't become price bloated with wireless crap and internet stuff that hardly anyone will use. But the option is still there for those who want to.

 

One poster even mentioned the idea of sitting outside the boat looking at his mobile phone to check the batteries. I admit that's not something I'd ever want to do but if that's what someone wants then they can still do it and it doesn't really affect the price of the unit. It only affects them because they have to go and buy a wireless router.

 

Thus covering both scenarios and dealing with them both. So why bring up one as if it's everyone else who is daft?

 

You're not paying attention.

[Evo]

Customer calls customer support

 

Customer support call Gibbo

 

"Gibboooo!!!!! I've got a bloke on the phone here who says he cant ping his battery monitor, WTF is he on about".

 

"Gibbooooo!! This bloke says his battery monitors got a VIRUS...how does he virus check it..??"

 

"Geeeeeeboo!! Me again, this ones forgotten his password and his encryption key, and his IP address"

Edited December 1, 2010 by Evo

[stuart]

Simples...

 

"Gibboooo!!!!! I've got a bloke on the phone here who says he cant ping his battery monitor, WTF is he on about".

"Gibbooooo!! This bloke says his battery monitors got a VIRUS...how does he virus check it..??"

"Geeeeeeboo!! Me again, this ones forgotten his password and his encryption key, and his IP address"

 

Sounds like a way to make more money !

 

A measuring module with a simple plug in link to the display. The module goes near the batteries for ease of wiring (there's a lot of wiring to monitor (say) 4 battery banks for voltage, current, temperature and so on) and the display goes where the user feels it is most convenient.

 

I can then put an ethernet interface in it and set up a web server inside the device.

 

Would the ethernet go to the display module or the sensor module? Could you have multiple sensor modules? Thinking bowthruster batteries vs engine batts ?

[WotEver]

Sounds like a way to make more money !

"Just hold on the line, caller, I won't be long" Watches minute counter wind up to £5 call charge... "Now sir, explain that to me again..."

 

Tony

[ditchcrawler]

I have something called Dynostar GPS and Air/fuel logger which ok are collecting alot more info but which I think are similar to what you are trying to achieve.

Is it really worth having this on a boat

[Gibbo]

Customer calls customer support

 

Customer support call Gibbo

 

"Gibboooo!!!!! I've got a bloke on the phone here who says he cant ping his battery monitor, WTF is he on about".

 

"Gibbooooo!! This bloke says his battery monitors got a VIRUS...how does he virus check it..??"

 

"Geeeeeeboo!! Me again, this ones forgotten his password and his encryption key, and his IP address"

 

"Not our problem, go and phone your router supplier, thankyou for calling, is there anything else I can help you with today?"

 

Simples...

 

 

 

Sounds like a way to make more money !

 

 

 

Would the ethernet go to the display module or the sensor module? Could you have multiple sensor modules? Thinking bowthruster batteries vs engine batts ?

 

I'm still pondering this. I have a hard time making a decision. BT batteries are a bit like engine start batteries. They will either start the engine/run the BT or they won't. Whatever a battery monitor says is never going to change that. So there's actually not much point in monitoring them.

 

People expect to monitor engine start batteries even though it's useless (other than to make sure they are actually being charged) so we will be including that but monitoring a BT battery is, IMHO, utterly pointless.

 

We have to make a decision as to whether we're making a battery monitoring system or a boat diagnostics device.

Edited December 1, 2010 by Gibbo

[RLWP]

Could you do some clever communication between the monitor and the display through the positive and negative cables?

 

Richard

 

Perhaps you've already mentioned this

[Robin2]

For that, you could use a 741. All you want to know is whether the voltage across the shunt is positive or negative. Factor in an amount of hysteresis with feedback and use the output to switch a FET or similar.

 

Tony

 

Well I couldn't get it to work. It was fine until I switched the inverter on - which rather missed the point. Perhaps you have a link to somewhere with advice?

[Gibbo]

Well I couldn't get it to work. It was fine until I switched the inverter on - which rather missed the point. Perhaps you have a link to somewhere with advice?

 

Like almost all of electronics, it's really not as simple as people think.

 

What spec shunt are you using?

 

What current do you want it to switch at (plus or minus what?)?

 

How accurate do you want it?

 

Are you prepared to calibrate it it or does it need to be calibrationless?

 

Have you got a diagram of (or can you redraw) what you tried? It might be fixable.

 

I'll see what I can come up with, but don't expect a dead simple circuit because it isn't possible.

 

Could you do some clever communication between the monitor and the display through the positive and negative cables?

 

It's possible but it's not easy get any decent speed because of the amount of noise already on them.

[WotEver]

Well I couldn't get it to work. It was fine until I switched the inverter on - which rather missed the point. Perhaps you have a link to somewhere with advice?

You probably weren't snubbing the input sufficiently. You'll get all sorts of 'orrible back flows when you turn on a high current load like an inverter, which need to be removed/ignored.

 

Tony

[Robin2]

You probably weren't snubbing the input sufficiently. You'll get all sorts of 'orrible back flows when you turn on a high current load like an inverter, which need to be removed/ignored.

 

Tony

 

Thanks Tony. How do I snub? (serious question)

[WotEver]

Thanks Tony. How do I snub? (serious question)

Sorry Robin, but others are far better qualified than me to answer that one. As I stated in another thread (or was it this one?) earlier - I don't do circuit design, I just have to (used to have to) understand them when they're designed so's I can (could) test them.

 

I'd suggest a bit of Googling for "12V current meter switch" or something along those lines.

 

Tony

[nb Innisfree]

Don't know about any one else but I feel totally bewildered...

[Evo]

Don't know about any one else but I feel totally bewildered...

 

 

argh well your the guy talking to cust sup who doesn't have a router, he just has his laptop plugged into the LAN port of his new magic battery monitor, and this guy is sending you off to some router supplier you never had.

[RLWP]

Don't know about any one else but I feel totally bewildered...

 

 

argh well your the guy talking to cust sup who doesn't have a router, he just has his laptop plugged into the LAN port of his new magic battery monitor, and this guy is sending you off to some router supplier you never had.

 

Who's bewildered?

 

 

 

Richard

[Sunset Rising]

Don't know about any one else but I feel totally bewildered...

 

Its all witchcraft by boy, all witchcraft.

 

I believe ( for every drop of rain that falls ) that this thread is the techi equivelent of the punctuation thread that ran recently. Everyone makes intelligent comments ( except me ) but nobody really knows what the fusk is going on.

 

 

 

 

 

 

least ways I hope so, otherwise this is just another demonstration of how clueless I really am.

Edited December 2, 2010 by Sunset Rising

[WotEver]

Thanks Tony. How do I snub? (serious question)

Thinking again about this, you'd probably do better with a cheap Hall-Effect device as your trigger source and forget all about the shunt. However, I have no idea where you'd source a split-ring sensor.

 

Tony

 

Actually, Googling shows loads of suitable candidates under the term "Current probe" but they're all silly money.

[Chalky]

Thinking again about this, you'd probably do better with a cheap Hall-Effect device as your trigger source and forget all about the shunt. However, I have no idea where you'd source a split-ring sensor.

 

Tony

 

Actually, Googling shows loads of suitable candidates under the term "Current probe" but they're all silly money.

 

Have a look at the 758 from Allegro microsystems - available from Farnell. They are hall effect current sensor so the sensing is isolated from the voltage source. They need to be wired into the circuit - I've got one on a piece of brass so I can replace a mega fuse. They're not as linear or as accurate as a shunt, but are easier to work with.

[Gibbo]

At start-up, broadcast DHCPDISCOVER packets and wait for a response from a DHCP server "out there". If you see a DHCPOFFER, go through the DHCPREQUEST/DHCPACK handshake, get an IP address and you're done 'till the lease expires when you renew. If, on the other hand you never see a DHCPOFFER, after a timeout go into "network master" mode. Configure the local interface with a static address (like 192.168.0.201) and start a DHCP server that listens for DHCPDISCOVER broadcasts from other hosts on the network.

 

Right, gotchya. I don't like the delays. For some reason people accept that plugging a PC into a LAN is allowed to takes ages before anything happens, ditto when they plug something into a USB 'old, but when it comes to my devices they expect it to happen instantly.

 

I shall ponder further.