Blue Solar Charge Controller help!

[pandos]

I have a 100w solar panel. It was linked to a Vectron PWM controller. Feeding my old AGM batteries.

The PWM provided some charge on occasions. It turned out that the panel was faulty, the connections had not been soldered. Following repairs I got fairly consistent charging although not very much of it. about 3amps.

I have a NASA BM and this seems to reflect the state of charge of the batteries. When I start the engine I get about 15 amps in...when just a few lights and the radio is on it shows just a few amps going out I think it is accurate, and it tally's with my multimeters in terms of the battery voltage.

I fitted new AGM batteries last winter. And was getting some charge from the PWM.

A few weeks ago I fitted a new MPPT charger. (I did not go for the one with the built in Blue tooth).

Over the weeks it has shown almost no charge, in fact my instinct is that it is taking charge out of the system. When I fitted it the green led flashed and the yellow led remained constant. This seemingly indicates battery activity and that the system is at float.

Yesterday I investigated, I ran new cables from the panel. To the MPPT. The controller is only about a foot from the batteries and the cables are all visible. There was no change in the LEDs.

I measured the voltage across the panel connections at the controller it was something about 20.5v maybe a little more but it seemed satisfactory.

Across the battery connections on the MPPT it showed 13.7v but at the batteries themselves (about 18 inches of stout cable away) the voltage is 12.5v. how can this be?

It seems that the MPPT is not putting out much charge because it senses the batteries as being at 13.7v. even though they are much lower than this.

Is this a quirk of these systems trying to be too clever which might resolve after a period of darkness, when there will be no source of voltage above 12.5v,?
Or is it likely to be a faulty controller.?

My instinct is that if I had the Bluetooth gizmo which plugs into it I would tell it to bulk charge until 14.4v and see if it came to life...but I'd rather pay for a second panel than add further complications to the system.

BTW I do not have a jumper in the connection, (I lost it?) but I think with no jumper it should still work.

 

[RupertW]

If there is a different voltage at either end of the cable to the batteries then there must a problem with the connections or the cable itself. Can you try replacing cleaning and checking the connections and/or replacing the cable?

 

[Daverw]

I can only see it being a bad connection between controller and batteries

 

[pandos]

If there is a different voltage at either end of the cable to the batteries then there must a problem with the connections or the cable itself. Can you try replacing cleaning and checking the connections and/or replacing the cable?

it seems perfect...it is fused so perhaps an issue there, I'll replace the cable with a continuous piece next time I get to boat, just to be sure..

 

[sailaboutvic]

Can you put a current meter over one of the wires ?

 

[pandos]

Can you put a current meter over one of the wires ?

Ultimately the BM is a current meter which is showing .8amps charge.

Not sure which other wire you think it would be good to put a current meter on. ?

if I understand correctly, even if the current is available from the panel, the controller won't let it flow unless it thinks the batteries can take it/need it.

 

[sailaboutvic]

Ultimately the BM is a current meter which is showing .8amps charge.

Not sure which other wire you think it would be good to put a current meter on. ?

if I understand correctly, even if the current is available from the panel, the controller won't let it flow unless it thinks the batteries can take it/need it.

From the mppt to the batteries,
Silly question have to set the mppt to your battery type .
If the mppt thinks battery full it won't anything flow .
You can also try putting a meter at both ends of any fuses you have and see what the voltages reads

 

[pandos]

From the mppt to the batteries,
Silly question have to set the mppt to your battery type .
If the mppt thinks battery full it won't anything flow .....

Not a silly question at all. The only option to set the battery type is using the jumper.

Afaik without a jumper it should put out during absorption to 14.4 and float at 13.8.

I still can't get my mind around the question of it is sensing 13.7 at the end of the cable which has 12.5 at the other end, if the cable is bad it should be seeing less than 12.5. And therefore it should put out 14.4.....

The more I think about it the more I tend to believe that it won't work without buying the additional Bluetooth gizmo...

But as I said I'll try a new cable to the batteries as a next step...and I'll put a current meter on that.

 

[sailaboutvic]

Mine are Bluetooth.
But if I remember rightly the jumper is just for the load , so if your not use in the load side you don't need the jumper , someone correct me if am wrong .
Also can't you just buy a dongle to turn your into Bluetooth?

 

[pandos]

Mine are Bluetooth.
.....
Also can't you just buy a dongle to turn your into Bluetooth?

I could and perhaps then I find that I have a dongle for a faulty controller.

I do appreciate that it would aid diagnostics, but If one is necessary they should say this on their blurbs....

I'd rather get this one right and if it is faulty or there is a fault in my system to identify this first...

Thanks for the suggestions...

 

[RupertW]

Not a silly question at all. The only option to set the battery type is using the jumper.

Afaik without a jumper it should put out during absorption to 14.4 and float at 13.8.

I still can't get my mind around the question of it is sensing 13.7 at the end of the cable which has 12.5 at the other end, if the cable is bad it should be seeing less than 12.5. And therefore it should put out 14.4.....

The more I think about it the more I tend to believe that it won't work without buying the additional Bluetooth gizmo...

But as I said I'll try a new cable to the batteries as a next step...and I'll put a current meter on that.

So the reason a bad connection would show 13.5 at the MPPT and 12.5 at the battery would be that the MPPT is trying to charge the batteries and the resistance of the corroded wire or poor connection will cause a voltage drop so a volt lower at the battery end.

It’s not seeing 13.5 at the battery it’s producing it.

 

[pandos]

So the reason a bad connection would show 13.5 at the MPPT and 12.5 at the battery would be that the MPPT is trying to charge the batteries and the resistance of the corroded wire or poor connection will cause a voltage drop so a volt lower at the battery end.

It’s not seeing 13.5 at the battery it’s producing it.

Hopefully you are correct....
But should it not produce higher than 13.5 (14.4) unless it senses 13.7....thats where I am stumpted...

 

[RupertW]

Hopefully you are correct....
But should it not produce higher than 13.5 (14.4) unless it senses 13.7....thats where I am stumpted...

Typically the settings are to go up to 14.4V and hold at that for a while (absorption) then drop to 13.3V but default settings could vary.
So if it thought the battery was at 14.4 then it could now be back down to float with a low current. However big voltage drops only really occurs with a fair bit of current running through so it’s all a bit odd.

But until you cure the difference in voltage at either end of the cable you won’t really know what is going on. I presume you measured both ends with the same multimeter?

 

[sailaboutvic]

Just a tho , you are setting the meter to zero each time ? On mine if you don't it reads incorrect.

 

[pandos]

Yep...... I am using the multimeter correctly, I have checked against another and they and the BM all show the same voltage...

One thought is that the MPPT was not programmed correctly or that someone fitted it before me and rejigged the settings before sending it back to Amazon...

But yes I must first sort the mystery of the different voltage across a relatively short cable...

The more I think about this and having considered the replies.....it must be a fault in the cable... After all, the body of the multimeter itself is probably further from the MPPT than the battery connection.

 

[Aja]

Could you swap in your old PWM controller and see if your getting the original 3A?

 

[pandos]

Could you swap in your old PWM controller and see if your getting the original 3A?

As a last resort....but I think I will stick to trying to solve the mystery of the wire to the batteries... Logic says this must be an issue...

 

[clyst]

Is yourBM a No-1 ? if so you probably ly need a BM2...... Check it out .

 

[Keith-i]

You need to check for voltage drop along your cables. Start with the positive say. Place one multimeter lead on the battery post and the other on the solar controller outlet. Any voltage reading between these two points suggests resistance in the cable. Based on your quoted voltages you might get a 1v reading on one or other of the cables.

 

[sailaboutvic]

If as you say the yellow light stays on it means the mppt is in abs state which is why it's not letting any current to the batteries.
You could start with what Keith said and do a voltage drop I suggest you have loads on at the same time ,
You maybe best to re wire the mppt to the batteries too.
I just took a look at mine this morning , it's very over cast , no sign of any sun , my 150w panel is pushing 1.2 A,
panel voltage 20.1 V
batteries 12.5v at the mppt and at the batteries.
Only blue light on which mean it's I'm bulk charge .