Alternator? D+?

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tim.shaw
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Alternator? D+?

Post by tim.shaw » Sat May 16, 2020 11:12 pm

Sorry.
I'm not quite that dumb, I'm just hoping someone can point me at the info I need.
I don't know the engine compartment of a Bongo (although I had a look when a flood impact ripped off the underskirt bit, and I know where the alternator is).
I have difficulty moving the driver's seat and having a look for myself, so I'm being cheeky and asking before I go in ...
I'd like to tap the D+ of the alternator to feed it to a Votronic VCC 1212-30. I assume there is a D+ feed - I'd like to know if there isn't as well.

Q : If I go in via the driver's seat, will I be able to locate and tap the D+? Is there a better way?

I apologise if the info is readily available - any pointers would be much appreciated.

Many thanks

tim
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g8dhe
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Re: Alternator? D+?

Post by g8dhe » Sun May 17, 2020 8:53 am

Have you located the wiring and mechanical diagrams ?
Mechanical at http://www.lushprojects.com/bongopartsmk2/
and Wiring diagrams here http://www.g8dhe.net/bwm/default.htm you will need Flash and enabled for the site
Geoff
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tim.shaw
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Re: Alternator? D+?

Post by tim.shaw » Sun May 17, 2020 7:35 pm

Ouch. Sorry.
I've looked at multiple wiring diagrams, and can't make head nor tail of them with reference to real life.
I was just following installation instructions, and hadn't heard of D+ before and thought someone might know.
Turns out I'm looking for the voltage sense wire, which may or may not exist. I just didn't understand and hoped a simple question would get some advice. I've installed it without the D+, which is fine but not optimal.
I still haven't found the alternator tho'.
Thanks anyway.
tim
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Re: Alternator? D+?

Post by g8dhe » Sun May 17, 2020 10:04 pm

Its on the Alternator page ;-)

Nothing complicated Earth, Charge signal wire to the dashboard light, main alternator output and the field coil connection.
Geoff
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tim.shaw
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Re: Alternator? D+?

Post by tim.shaw » Mon May 18, 2020 11:38 pm

Thanks for that - I spent a while enabling Flash, but it was worth it. My model manual's not ready yet, but I'll assume the general principle ...
Am I correct in reading that I can take the X-20 wire (G/R) from the alternator and tap that to take a voltage reading from the alternator output?
I don't know the Bongo internals and I just wanted a steer.
I certainly don't want to interfere with correct operation ...
The requirement is to read the alternator output (which I think that is).
If that wire does that, I'm happy - I just need to find the alternator (and the wire) next.
Thanks for your patience.
tim
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Re: Alternator? D+?

Post by g8dhe » Tue May 19, 2020 8:50 am

No the X-20 is the Charging light signal to the dashboard, its earth when the alternator is NOT generating and floats high to battery voltage when it is operating.
The alternator output is the thick lead Black/Red going to the 100 Amp fuse. You don't really want to physically intercept that at all!

Ah just found out what the device is your trying to fit, intrigued why you have gone that route and not use a standard Split Charge Relay ? The alternator on a Bongo is well rated and quite capable of charging both batteries as it is rated at 90 Amps.
Geoff
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tim.shaw
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Re: Alternator? D+?

Post by tim.shaw » Tue May 19, 2020 12:13 pm

Isn't X-20 the one I want? It's only going to be attached to a sensor, which determines the actual voltage coming from the alternator? No load. It's labelled as D+ for the unit (hangover from dynamos apparently). I think I would need to take it from between the alternator and the ignition relay - which, as you say, should be 0 (ground) when alternator is not generating and rise to the alternator's output when it's running.
If the voltage rises to starter battery voltage when the ignition is switched on (excitation mode), then it's of no use in this case :
Quote from the unit manual 'If need, the control input "D+" can also be connected to the vehicle Kl.15 (ignition ON), but in this case, the STARTER
battery might be inadvertently strongly discharged when the engine is stopped
!'
It doesn't matter for the moment as the unit is working perfectly without the D+ ... it's just that it would be more efficient if it had it.

I had a Zig CF9 which, when my leisure battery went 'open circuit' happily fed all the volts in the starter through the leisure battery and down to earth. I didn't wire in the Zig. I was a little surprised to see the leisure battery didn't have a earth strap - just a little wire to the Zig (live went to the starter).
I wanted to replace the Zig anyway so I checked the current(!) options.

I investigated various split-charge approaches, and was concerned at the power draw when the battery was flat. The Votronic unit manages the feed from the starter battery/alternator and puts it to the leisure battery at the 'correct' level, when the voltage difference is high enough, according to standard battery charging profiles.
Now the leisure electrics are on a completely isolated circuit, and the voltage from the leisure battery is 'damped' - which is good as I'm running computer equipment and audio stuff from it.

When the engine is off, I get 13.0+ (stable - it's a new battery) and when the engine is running I get a consistent 14.4 (showing that the leisure battery is charging).

It's a very tidy system and the entire thing fits very nicely under the bonnet. The 2 batteries are linked (via the unit) using 16mm2 battery cable (fused at the batteries) and both have earth straps. Then I've run 2 twin-core 30amp cables (fused) from the leisure battery - one to the rear, and one to the glove-box. Each of these goes into a distribution/fuse box.

I like simplicity, and this is about as simple as it gets - and I'm confident that it's electrically safe.

Anyone want a Zig?
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g8dhe
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Re: Alternator? D+?

Post by g8dhe » Tue May 19, 2020 1:23 pm

The signal on X-20 is NOT what you want, it is connected to earth when the alternator is not generating, and connected to the dashboard light and hence to the battery when the ignition is turned on.

What is this connection "D+" that your referring too, it sounds like Dynamo +ve output, in which case you will damage both the alternator and the device if it powers up when the alternator is not generating!!!

You mention an "Ignition relay", what do you mean by this term? There isn't such a relay in a Bongo, there is a relay to power-up the starter motor solenoid and there is a protection relay on the petrol versions but not the diesel version.

The purpose of a Split Charge Relay is to isolate the LB from the SB when the engine /alternator is not running, there will not be a drain if correctly installed from the SB to LB.

You say
When the engine is off, I get 13.0+ (stable - it's a new battery) and when the engine is running I get a consistent 14.4 (showing that the leisure battery is charging).
so where is this charging power coming from currently ? It sounds like you have SCR installed already or your relying on the CF9 ? Or maybe you have the device added already ?
Geoff
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tim.shaw
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Re: Alternator? D+?

Post by tim.shaw » Wed May 20, 2020 3:21 pm

Thanks, and sorry for your obvious frustration.
I now know that the Alternator does not have a D+ (or equivalent).
I had installed it without, hence my readings, and it is working fine.
It would have been good it there was a D+ as the unit would be more sensitive.
Best Regards
tim
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