Is my PWM regulator kapput?

[ElliesBoss]

Before we start, our motor home is in storage so I have no access to mains. I pass the storage site on my way to Tesco (other supermarkets are available) so I drop off about once a fortnight to have a quick check. Battery voltage is normally above 12v. Not brilliant but OK. Today I checked it out and the batteries (cab and hab) are totally dead (about 4V). No lights or displays anywhere apart from the green charging light on the PWM. I have 20V at the input to the regulator and approx 0.8 A measured from the input +ve to the leisure battery +ve (not seen the sun all day!). From the PWM output +ve to leisure battery +ve I get zilch. I've checked the fuses in the cable to the battery and they are fine.

PWM issue? Anything else I can check to confirm it's the PWM or could it be something completely different? Thanks for any answers.

 

[funflair]

I don't know how much solar panel you have but this time of year there is very little gain PWM or even MPPT.

So 20v from the panel suggests that is OK but I am not 100% sure what you are saying about the amp measurement, have you disconnected something and measured amps inline?

 

[Raul]

The battery is to low for the regulator to work. Hence you see open circuit voltage on the solar side , of 20v. This is how you fry a controller, low batt or no batt at all. The solar should be isolated in this circumstances. As for battery going. Down to 4v it could be dead short on battery cells or something took out more than solar could replace over a period of time. My guess the controller did stoped charging once the battery went bellow 10,5v. Something pulled the battery down.
Do you have a fuse from controller to battery? What size and how much solar do you have?

 

[ElliesBoss]

I don't know how much solar panel you have but this time of year there is very little gain PWM or even MPPT.

So 20v from the panel suggests that is OK but I am not 100% sure what you are saying about the amp measurement, have you disconnected something and measured amps inline?

Yeah. Used an ammeter to measure current going direct from solar panel to leisure battery +ve so I know that current is available into the PWM. Then ammeter from PWM out direct to +ve terminal of leisure battery and nuffink!

 

[Richard n Ann]

You've either got a big drain or the PWM is faulty. First job, Take the batteries home and give them a charge.. Then when you go back you can do some fault finding

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[Raul]

Yeah. Used an ammeter to measure current going direct from solar panel to leisure battery +ve so I know that current is available into the PWM. Then ammeter from PWM out direct to +ve terminal of leisure battery and nuffink!

You don’t have any current flow, you got voltage. Current 0. If there would been any current flow the voltage would of been less than 20v and lots of heat on the controller. The energy does not disappear.

 

[ElliesBoss]

You've either got a big drain or the PWM is faulty. First job, Take the batteries home and give them a charge.. Then when you go back you can do some fault finding

I've got the cab battery on normal charge at the moment and then will stick it through a "recovery" cycle. Do the leisure tomorrow.

 

[ElliesBoss]

You don’t have any current flow, you got voltage. Current 0. If there would been any current flow the voltage would of been less than 20v and lots of heat on the controller. The energy does not disappear.

Understand that. What I established was by by passing the PWM there would be current available from the solar panel if the PWM was able to make use of it. As it doesn't I was assuming something was open circuit in the PWM.

 

[ElliesBoss]

The battery is to low for the regulator to work. Hence you see open circuit voltage on the solar side , of 20v. This is how you fry a controller, low batt or no batt at all. The solar should be isolated in this circumstances. As for battery going. Down to 4v it could be dead short on battery cells or something took out more than solar could replace over a period of time. My guess the controller did stoped charging once the battery went bellow 10,5v. Something pulled the battery down.
Do you have a fuse from controller to battery? What size and how much solar do you have?

Sorry. Didn't answer your questions. 2x80w panels in series and 10A fuses.

 

[Raul]

Disconnect the panels, bring the battery up with the charger. If the charger does not want to start charging, you will have to piggyback in parallel with another battery to provide a voltage where the charger accepts it.
Once the battery is at least 11,5v, the controller should see the battery and turn on. Then connect the panels. It’s important the controller is powered up from battery first, before any panel input.

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[stevewagner]

Before we start, our motor home is in storage so I have no access to mains. I pass the storage site on my way to Tesco (other supermarkets are available) so I drop off about once a fortnight to have a quick check. Battery voltage is normally above 12v. Not brilliant but OK. Today I checked it out and the batteries (cab and hab) are totally dead (about 4V). No lights or displays anywhere apart from the green charging light on the PWM. I have 20V at the input to the regulator and approx 0.8 A measured from the input +ve to the leisure battery +ve (not seen the sun all day!). From the PWM output +ve to leisure battery +ve I get zilch. I've checked the fuses in the cable to the battery and they are fine.

PWM issue? Anything else I can check to confirm it's the PWM or could it be something completely different? Thanks for any answers.

You can have voltage without current but not current without voltage

 

[ElliesBoss]

Don't suppose anybody is interested but here goes. Charged all the batteries with smart charger. Charged all batteries in recovery mode. Recharged in normal mode. Refitted batteries the following weekend (30th Jan). Been shopping today so dropped off to have a look. Batteries all still fully charged. Weird or what?

 

[Raul]

What voltage? That would be a indicator if solar is working or batteries just kept the charge since you home recharged them.

 

[ElliesBoss]

14V. Alarms been on. Found it hard to believe so I tried starting it. Engine burst into life when I tried it. I didn't believe the batteries would have held their charge after being so utterly depleted.

 

[Raul]

You brought them back gradually, and maybe they haven’t sat to long at low voltage. It might been a bleep on the solar controller and needed resetting, power off-power on, or you might had a temporary obstruction on the panel. It’s nice to have feedback, that’s how we learn from each other. Thank you.