Hi all,

Noticed yesterday the battery values on ICC went missing. The thread seems to be running, as per ICC. When I got home, the display on the bmv was dead. Replugged the usb cable both side, then tried other free usb ports on the pi. Nothing.

Is there a way to test if it is the ve-bus usb cable? or is it the bmv itself that faulty? Approx 2 years and 3 months old.

You comments/suggestions/? are welcome

51 minutes ago, Sidewinder said:

the display on the bmv was dead

That seems to suggest that the BMVis not getting any power, and this power is via the RJ-11 cable that runs from the shunt. So I would check that first. There is a small fuse in the red wire going from the battery positive to the shunt. Check this fuse.

I quickly checked on an old broken shunt I have: If you hold the cable so the plug points upwards with the tab away from you, the positive feed is on the right-most pin, and the negative on the third pin from the left. So you can check if there is power to the unit from the shunt.

If there is power but the display remains off... then talk to the supplier about warranty matters. If there is no power but the fuse is good, then similarly have the shunt checked for possible replacement (sometimes the PCB on the shunt goes bad... but usually only if it is exposed to the elements).

51 minutes ago, Sidewinder said:

Is there a way to test if it is the ve-bus usb cable?

It's a VE.Direct cable. It is unlikely that it is this cable, since the BMV is not powered this way. It gets its power from the shunt.

Edited February 22, 20197 yr by plonkster

@plonkster

Thanks for the tip. I would habe never thought that it gets it's power from the shunt. Yes, i haven't inspected this yet and probably a lot of oxidation present. Will dissassemble tomorrow and see if the cause. Let's hope so. I have cleaned one of the battery terminals nearby recently that had a bit of gumpff on it.

9 minutes ago, Sidewinder said:

lot of oxidation

Local house here in Somerset West. Installer asks me to help out as he doesn't know the BMV that well. Shunt is sitting outside inside the battery box (which used to house a bunch of flooded lead acids, then got modified for SLAs.. but the thing is hardly water tight). So the shunt is badly corroded, I take it home, clean it off, try and resolder the joints... but the thing is dead. Customer buys a complete new BMV and we replace it. I say to the installer... do me a favour and lets put it in an enclosure. Day of the fix arrives... installer bought no enclosure. Shunt is afixed in the old place, two screws are inserted underneath to offset it a bit... so the rain doesn't hit it directly...

I figure... bloody hell. But this whole thing is done only so they can get it in a shape to sell the house, so I keep my mouth shut and get out of there 🙂

8 minutes ago, plonkster said:

Shunt is sitting ... inside the battery box ...

I was that stupid. Now it is far far away from the fumes. 🙂

@cpbotha, my story above... the one that fired you.

Hi all,

So did the inspection on Saturday...sorry for reporting now only...found the fuse to be overgrown with a white substance on the one side, so much so the the body cracked. Upon opening the fuse holder, found the fuse to be intact, but the one side (connected to the battery) is totally corroded. Quick brush with fine emery paper hopefully will do the trick. I will re-install the 702 this afternoon and hopefully this will do the trick. Will update later..

In the mean time I've got some muti from a buddy who used to work on cellular towers, looks like a type of sealing grease, will apply and hopefully keeps the gumpf away. Would better ventilation prevent/minimise this stuff from growing? In 2.5 years, I've had to "clean" the furthest terminal from the shunt (i.e. the + of the bank) a few time already.

1 hour ago, Sidewinder said:

white substance

The same stuff you see growing on battery terminals? That is usually some kind of sulphate, and likely a reaction between the Hydrogen Sulphide gas from the batteries and whatever metal the contact is made of inside that fuse holder. It tends to show up with a greenish tint on copper (Copper sulphate).

Hi all,

So re-installed the 702 yesterday afternoon, and bob's your uncle. All 100%.

So here is a image of the gumpf I'm talking about. a White substance on the nut and one can see the Copper Sulphate starting to form on the bus bar. The fuse was full of the white stuff. Rest of the terminals of the battery bank is clean.

Any suggestions on:

1) how to clean properly?

2) How to effect prevention?

Thanks

Edited February 26, 20197 yr by Sidewinder

Clean with bicarbonate of soda. Spray with Q30 (protective film) or similar when dry.

Also (as was pointed out me me when I arranged my batteries in a neat block), you need some air space between the batteries to prevent heat buildup.

Edited February 26, 20197 yr by DeepBass9

47 minutes ago, DeepBass9 said:

you need some air space between the batteries to prevent heat buildup.

Jip, as per Trojan docs, leave a bit of space between the batts, like 1cm if you can.

There is probably a little bit of H2S leaking from where the lead and the plastic housing join that is causing the sulphate build up. if you put the cable on the other side of the terminal lug, you shouldn't get the sulphate buildup. That white stuff is ZnSO4 from the galvanising on the nut.

If you think about it you can tell the whole corrosion history by the colour of the salts, copper sulphate is blue, zinc sulphate is white, iron sulphate is brown, nickel sulphate blue, etc.. 

Edited February 26, 20197 yr by DeepBass9

Hi All,

Thanks for all the feedback on remedies and spacing. Will do the neccesary tomorrow.

You can also use Petroleum Jelly (vaseline) on your terminals. Been using it for years with no sulphate build-ups.

14 hours ago, GVC said:

Petroleum Jelly

That stuff is underrated. I even use it on my bicycle chain. I know there are specialist lubricants that are better, but man this works well.

On 2019/03/03 at 9:53 PM, plonkster said:

That stuff is underrated. I even use it on my bicycle chain. I know there are specialist lubricants that are better, but man this works well.

and it works great on squeaky door hinges

On 2019/02/23 at 3:01 AM, ___ said:

If you hold the cable so the plug points upwards with the tab away from you, the positive feed is on the right-most pin, and the negative on the third pin from the left. So you can check if there is power to the unit from the shunt.

Thank you Plonkster for this info.

I also had a "dead" BMV702 after 4 yrs operation. I checked for Voltage at the end of the cable as per your directions and all was good there so I have ordered another BMV702 at a cost of $200. I hope this one lasts longer than 4 yrs!!!!

All you guys in the good old RSA take care. According to the TV news things are a little tough there atm. i went there for a 2 week holiday in 1972 and stayed 7 yrs. Very fond memories of Hillbrow and surrounds. All the best to you.