Alternator connection

As far as the battery monitor is concerned it is the way in which the shunt and all the negative connections are made to the batteries that is important.

The instructions for wiring the BM1 must be followed exactly.

This diagram may help although NASA have improved their instructions a little since I drew it.

scan0058.jpg

The orange wire supplied with later BM1s to provide a voltage reading on the starter battery is not shown.

No attempt has been made to show how the battery positives and the isolator switches are connected to control battery use and charging. Post a diagram that shows how this is/will be done and it will be possible to comment on it..
 
VicS said:
As far as the battery monitor is concerned it is the way in which the shunt and all the negative connections are made to the batteries that is important.

The instructions for wiring the BM1 must be followed exactly.

This diagram may help although NASA have improved their instructions a little since I drew it.

scan0058.jpg

The orange wire supplied with later BM1s to provide a voltage reading on the starter battery is not shown.

No attempt has been made to show how the battery positives and the isolator switches are connected to control battery use and charging. Post a diagram that shows how this is/will be done and it will be possible to comment on it..
Click to expand...

Thanks VicS, my BM-1 is connected exactly as you sketched, I have double checked it with the instruction manual also.

I am not sure how to put a sketch like you have, but my investigations show that the output from the B1, switch go to the first 180 battery, which is in parallel with the second one. B2 feeds the 75amp starter battery. Both switches, they are old type with detachable 'L' handles, are fed from the alternator via a commom busbar. I could do a sketch but how to show you is a problem, I would be happy to photograph it and email it. On the other hand it cannot be difficult to put on here with some help.
 
nigelmercier said:
This is a problem, see Vic's diagram. The alternator should ground on the negative busbar, on the side of the shunt away from the battery.
Click to expand...

I appreciate that Nigel, the alternator is grounded to the engine and by wire to the starter motor also, which is on the 'shunt side' away from the battery, unless there is something I am missing.
There is another concern I found when checking my wiring, the starter motor has two connections to it, one ont the end and one on the body of the motor, both are grounded, at least my meter tells me they are, one terminal of the starter solenoid gets continuity to both, any explanations please.
 
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Sarnia said:
Tyring to find how to post photographs taken, site not a lot of help, then it could be me!
Click to expand...

You can upload them directly as attachments ... there are size limits which depend on the file type ...... and a limit to the number of photos that the forum will store which is one reason at least why prolific users find the system next to useless.

If you dont have, dont want or dont want to figure out how to use Photobucket type your post, select "go advanced", scroll down to "additional options" and "manage attachments". Its easy enough .. the only complication is perhaps the size limit. IMHO easier than using P'bucket if you are not familiar with that. Like PVB though my own preference is to use P'bucket but I have used it so much that I can do it with my hands behind my back
 
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VicS said:
You can upload them directly as attachments ... there are size limits which depend on the file type ...... and a limit to the number of photos that the forum will store which is one reason at least why prolific users find the system next to useless.

If you dont have, dont want or dont want to figure out how to use Photobucket type your post, select "go advanced", scroll down to "additional options" and "manage attachments". Its easy enough .. the only complication is perhaps the size limit. IMHO easier than using P'bucket if you are not familiar with that. Like PVB though my own preference is to use P'bucket but I have used it so much that I can do it with my hands behind my back
Click to expand...

Thanks VicS, trying it now.

Get to manage attachments ok, drag and drop into it but it fills it, how do I get it to the post....
 
nigelmercier said:
This is a problem, see Vic's diagram. The alternator should ground on the negative busbar, on the side of the shunt away from the battery.
Click to expand...

It isn't a problem. As long as the shunt is the only thing connected to battery negative, the battery monitor will work as intended.
 
Sarnia said:
Thanks VicS, trying it now.

Get to manage attachments ok, drag and drop into it but it fills it, how do I get it to the post....
Click to expand...

Sorry not had the opportunity to look into this. It's changed since I last used the attachment method of posting pictures



Sarnia said:
I appreciate that Nigel, the alternator is grounded to the engine and by wire to the starter motor also, which is on the 'shunt side' away from the battery, unless there is something I am missing.
There is another concern I found when checking my wiring, the starter motor has two connections to it, one ont the end and one on the body of the motor, both are grounded, at least my meter tells me they are, one terminal of the starter solenoid gets continuity to both, any explanations please.
Click to expand...

Not sure what connections on the starter motor and solenoid you are looking at.

One expects to see a small terminal on the solenoid, which is the connection to the coil and two large connections which are the connections to the switched contacts.
There will be only a low resistance between the small terminal and the negative or ground.
One of the large terminals will be connected directly into the starter motor. There will be negligible resistance between this and ground.
The other large terminal will be the main battery positive connection. There should be no continuity between this and ground.

There may be a negative connection. If there is there may or may not be continuity to the starter motor body.

It would be helpful to know what the engine is. Make and model.

nigelmercier said:
If the alternator is grounded, I don't see how you could wire up a shunt correctly, unless you routed the starter battery through it.
Click to expand...
As in my diagram. The "all negative connections" includes the negative connection(s) to the engine
 
nigelmercier said:
Totally agree. My point is that the OP said the alternator is grounded.
Click to expand...

Most alternators are grounded, via the engine block. But it makes absolutely no difference to the correct operation of the battery monitor. As long as the shunt is the only thing connected to the battery negative, it will accurately measure all the current in or out of the domestic battery.
 
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