Alternator charging light staying on. Renogy DCC50S

[growly_bear]

I don't think I would trust the AliExpress item, and in any case it doesn't seem to include any BT connectivity, so has less adjustability than the Ablemail unit.

However, it does seem like a more sophisticated version of the BatteryMaster type devices in that it actually uses a relay to turn charging on or off according to the voltage thresholds you set, though how stable these are with temperature changes is open to question.

Still, as far as I know the BatteryMaster type gadgets are entirely passive devices which just use the voltage drop across a diode to control charging, which is a very crude way to do it!

I know it's from China, and yes, it probably won't be as robust as a more reputable make. However, the idea of setting charge start and stop voltages is exactly what I need to do (to get around the Renogy self activation saga). I've got one on order and hope to set it up using a small bench PSU (which I used to top balance my LiFePO4 cells). I'd never thought of temps affecting it.

I'm expecting the relay to be NO, so if it fails it won't constantly charge the starter battery. But that doesn't stop sone other aspect causing it to fail closed!

Where in the East Midlands are you? I'm in Chesterfield. If this fails I might ask to borrow your BT module for some beer tokens!

 

[fred_jb]

I know that it's just an alarm setting, and maybe I wasn't clear. I guess that your shunt could be over reading, but surely that's easy to check and compare with bat voltage Vs App

Yes, good point, I will at some point check all the device readings at their terminals against my multimeter to see which is giving the most accurate readings.

At the moment voltages of both batteries are reported by the DC-DC, the shunt, the Ablemail app, and also the LED displays which I connected across the Ablemail terminals. These things all have somewhat different wiring paths to the batteries so I guess it's not surprising that the readings vary.

 

[fred_jb]

I know it's from China, and yes, it probably won't be as robust as a more reputable make. However, the idea of setting charge start and stop voltages is exactly what I need to do (to get around the Renogy self activation saga). I've got one on order and hope to set it up using a small bench PSU (which I used to top balance my LiFePO4 cells). I'd never thought of temps affecting it.

I'm expecting the relay to be NO, so if it fails it won't constantly charge the starter battery. But that doesn't stop sone other aspect causing it to fail closed!

Where in the East Midlands are you? I'm in Chesterfield. If this fails I might ask to borrow your BT module for some beer tokens!

Yes, on balance it sounds like it might be worth a try with the AliExpress unit. However, you would be very welcome to have a go with my BT module. I live in East Leake which is between Nottingham and Loughborough. Just PM me for exact address if you are down this way anytime and want to call in. No beer tokens required!

 

[growly_bear]

Yes, on balance it sounds like it might be worth a try with the AliExpress unit. However, you would be very welcome to have a go with my BT module. I live in East Leake which is between Nottingham and Loughborough. Just PM me for exact address if you are down this way anytime and want to call in. No beer tokens required!

Cheers Fred! Ditto!!

 

[1967bowesj]

A little update on the Renogy reply to the dc dc not switching off

Think I’ll just stick to using the d+ wire to switch a relay, rather that than risk the voltage going below 11.5!!

And that’s after they said under no circumstances should the d+ be used with a standard alternator.

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[growly_bear]

A little update on the Renogy reply to the dc dc not switching off

Think I’ll just stick to using the d+ wire to switch a relay, rather that than risk the voltage going below 11.5!!

And that’s after they said under no circumstances should the d+ be used with a standard alternator.

View attachment 984217

I've had a few chats with renogy re the same. What is your 11.5v referring to?

 

[1967bowesj]

I've had a few chats with renogy re the same. What is your 11.5v referring to?

Theu state the charger will stop when engine battery gets to 11.5volts!

 

[growly_bear]

Theu state the charger will stop when engine battery gets to 11.5volts!

With my dumb alternator, the alternator charge led turns off at 12.7V. This is the voltage shown in their blurb and also the voltage which they started when I raised a 'case'. Mine extinguishes at 12.7V. Why are you thinking 11.5?

 

[fred_jb]

I have fitted a 100A relay inline with the starter battery/alternator input, operated by the D+ signal. I tested this today and it seems to works fine. The relay is a type normally used as a split charge relay.

I only had a couple of minor issues. The first was that the starter battery sense wire for my shunt used to come from the terminal on the DC-DC, so I had to relocate it to the live side of the new relay. Similarly I have fitted a dedicated mains trickle charger for my starter battery, connected via the DC-DC, so also had to relocate that to the live side of the relay.

 

[fred_jb]

Pic of under seat relay location:

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[1967bowesj]

With my dumb alternator, the alternator charge led turns off at 12.7V. This is the voltage shown in their blurb and also the voltage which they started when I raised a 'case'. Mine extinguishes at 12.7V. Why are you thinking 11.5?

Read the snip, that from their message to me. Their corrispondance has been very poor on this case.

 

[autorouter]

With my dumb alternator, the alternator charge led turns off at 12.7V. This is the voltage shown in their blurb and also the voltage which they started when I raised a 'case'. Mine extinguishes at 12.7V. Why are you thinking 11.5?

Just because the alternator has turned off doesn't necessarily mean the B2B will turn off. What they are saying is it can charge the leisure battery from the starter battery, until the starter battery is down to 11.5V. This is one of the reasons to use the D+ signal alone, and no voltage thresholds, on anything but a very simple system.

 

[growly_bear]

Just because the alternator has turned off doesn't necessarily mean the B2B will turn off. What they are saying is it can charge the leisure battery from the starter battery, until the starter battery is down to 11.5V. This is one of the reasons to use the D+ signal alone, and no voltage thresholds, on anything but a very simple system.

Sorry but I have to disagree. The spec is that the alternator charging stops when the starter battery drops to 12.7V. I also see this behaviour with mine.

As an aside, on the Renogy DCDC50S, with a dumb alternator, the D+ has no impact on the sensing voltage of the unit.

 

[growly_bear]

Read the snip, that from their message to me. Their corrispondance has been very poor on this case.

Apologies. On my phone I couldn't see the snip. I thought it was your signature and didn't zoom in.

Renogy have told you a different story to me. Have you seen your charging stay on below 12.7?

Incidentally, they did suggest the additional relay to prevent the charging.

 

[fred_jb]

Sorry but I have to disagree. The spec is that the alternator charging stops when the starter battery drops to 12.7V. I also see this behaviour with mine.

As an aside, on the Renogy DCDC50S, with a dumb alternator, the D+ has no impact on the sensing voltage of the unit.

Even with a smart alternator, which mine is, once the D+ signal turns off, the DCDC50S seems to revert to voltage control, and mine continues charging until the starter battery drops to about 12.7V.

Fortunately, maybe because smart alternators maintain the starter battery at a lower than normal voltage, I think generally around 12.5V, mine only takes a few seconds to drop below 12.7V once the engine is off, at which point the charging stops. Given this, I didn't really need to fit the relay but decided to do so just as a backup should the charging not always stop in the way it does at the moment.

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[fred_jb]

Read the snip, that from their message to me. Their corrispondance has been very poor on this case.

Seems odd that they should quote 11.5V in their message to you, when the manual seems to be saying that the level is 12.7V.

Have you actually seen it keep charging with the engine off to a point where the starter battery drops significantly lower than 12.7V?

Did Renogy give you a reason for not using D+ with a standard alternator as I find it difficult to see how that could be a problem.

I tend to agree that their support is not very confidence inspiring!

 

[1967bowesj]

Apologies. On my phone I couldn't see the snip. I thought it was your signature and didn't zoom in.

Renogy have told you a different story to me. Have you seen your charging stay on below 12.7?

Incidentally, they did suggest the additional relay to prevent the charging.

Yes, that was the reason I raised a case.
On fitting and testing it chartered well as I dropped the batteries ready to take a good charge, it continued after switching off down to 12.4, I wasn’t going to take the cab below that due to the airbag issues.
First they suggested the relay, I challenged them on this I expected the charge to stop around the voltage you see on yours. Not ready an issue though as I thought about fitting a switch so when I do fit lithium I can store them part charged on the travel home.
It’s interesting though that the d+ doesn’t control the charger better, must be a poor algorithm in their set up, there’s no reason for a charger to continue when alternator is off charge.
I think it has been pot luck with their tech team, the last advice just made my mind up on the mppt that was going to be the next upgrade.

 

[fred_jb]

It’s interesting though that the d+ doesn’t control the charger better, must be a poor algorithm in their set up, there’s no reason for a charger to continue when alternator is off charge.
I think it has been pot luck with their tech team, the last advice just made my mind up on the mppt that was going to be the next upgrade.

Yes, agreed. If they had a menu item that let you define the alternator type, then they could program it to work accordingly. As it is there are two scenarios which it should be able to differentiate even without a menu setting but seems like it is not reliably doing so.

Scenario A: This is a lowish starter battery voltage due to the intermittent and limited charging provided by a smart alternator which in the interests of fuel economy only tries to compensate for electrical loads just enough to keep the battery from going below I think about 12.4V-12.5V In this case it only needs to know that the engine is running with a smart alternator via the D+ signal to go ahead and take lots of charge out of the system, knowing that the smart alternator will up its game to compensate and stop the battery going flat.

Scenario B: There is no D+ signal but if a conventional alternator is running it will give a voltage reading of about 14V as it continually charges the battery and the device will use voltage sensing of that to give the go ahead to take lots of charge out of the starter battery, knowing that the alternator is working to replenish it. This should have some sensible lower limit, supposedly 12.7V, where it concludes that the alternator is no longer running, or if it is, it is no longer keeping up with demand, and so stops taking charge.

If this is how it works, then I can understand why they say not to connect a D+ signal if you have a conventional alternator, as that will make the thing think it can keep taking charge out of the starter battery even though it is only seeing a starter battery voltage of around12.5V which is what it would see with a smart alternator, so if people connect a D+ signal with a conventional alternator then they are giving the thing permission to take charge even when the voltage reading is only 12.5V.

However I don't understand why in my case it seems to keep charging for a short time when I turn off the engine, or turn off the D+ signal with the engine still running. I would have thought that when there has been a D+ signal present, which then ceases, that should tell it to immediately stop charging. Instead it seems to keep taking charge until the starter battery voltage drops down a bit. I can live with that as once the engine is off charging stops quite quickly. However, in your two cases it seems that it keeps charging to a lower than expected threshold. If you are feeding the device with a D+ signal with a dumb alternator, that might explain that behaviour, though even if you are, I would have thought that it would still respect the 12.7V threshold once the D+ signal is turned off, and not carry on taking charge down to 12.4V. Maybe it remembers that there has been a D+ signal so has a lower threshold for smart alternator maintained batteries? Maybe I need to check this again and see if mine really does stop at 12.7V or if it is actually lower.

Checking the manual, it says that for a smart alternator it will stop taking charge from the starter battery if it drops to 11.5V which seems too low, especially if the engine is off, but how does it know it is smart? Is it purely because a D+ signal has been previously connected at some point? It says that for a conventional alternator it stops taking charge once the battery is down to 12.7V, but maybe that won't be the case if you have ever connected a D+ signal with a conventional alternator. Might be worth disconnecting the D+ line and resetting the DC-DC to clear any memory it has, and then see if the behaviour changes. Maybe fitting a D+ controlled relay in the starter battery feed would be a better solution, especially for a conventional alternator, than trying to use D+ to control the DC-DC if you want to be able to stop the leisure battery from fully charging?

 

[1967bowesj]

Hi Fred, I did try it first just as bog standard no d+ it continues to charge after engine off till voltage gets down to at least 12.4 I disconnected it at that point.
Tried the d+ signal no different.
Now fitted a heavy duty relay off the d+ so it only charges when engine running.
Maybe I got that Friday one lol, customer support is very poor though.
No offer to replace but I can burden the return costs and get a refund lol, for something that is not working as advertised.
Hence me personally I will be very hesitant to purchase any other Renogy products.

 

[fred_jb]

Hi Fred, I did try it first just as bog standard no d+ it continues to charge after engine off till voltage gets down to at least 12.4 I disconnected it at that point.
Tried the d+ signal no different.
Now fitted a heavy duty relay off the d+ so it only charges when engine running.
Maybe I got that Friday one lol, customer support is very poor though.
No offer to replace but I can burden the return costs and get a refund lol, for something that is not working as advertised.
Hence me personally I will be very hesitant to purchase any other Renogy products.

Might be worth disconnecting the D+ and then resetting the unit to see if that changes anything. Not sure how to do this though. I thought I had seen mention of resetting in the manual but can't find it now. It is also not an option in the settings as far as I can see. Maybe you just have to disconnect it from everything and let it stand for a while? If you do that be careful to connect the leisure battery before solar as think the MPPT controller requires that.

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[1967bowesj]

Might be worth disconnecting the D+ and then resetting the unit to see if that changes anything. Not sure how to do this though. I thought I had seen mention of resetting in the manual but can't find it now. It is also not an option in the settings as far as I can see. Maybe you just have to disconnect it from everything and let it stand for a while? If you do that be careful to connect the leisure battery before solar as think the MPPT controller requires that.

Hi Fred, are you using the app/bluetooth connections?
Is it any good

 

[fred_jb]

Hi Fred, are you using the app/bluetooth connections?
Is it any good

Yes, I use the app all the time and find it very useful. The DC-DC/MPPT unit usually connects fine via BlueTooth and you can display all its info and change settings in the phone app.

I don't know if you have the Renogy shunt, but that can be more problematical and sometimes doesn't connect to the app easily. I put a switch in the 12V sense wire between shunt and leisure battery because that also powers it's circuitry, so switching it off and on again resets it and fixes any BlueTooth connection problem. It does have a reset button but in my case it is not easy to get to and doesn't seem as reliable as switching off and on.

The other complication in my case is that I have also fitted the One Core display which acts as a gateway between the Bluetooth enabled devices and lets you connect the phone app to them via a wifi signal, either from a router in the van or from the display's own wifi transmitter. It also has a levelling display which is useful in getting the van level. The only problem with this is that although you can see all the detailed info you don't seem to be able to change any settings on the DC-DC via that - you seem to have to turn off the display and have a direct BT connection to your phone to change settings.

 

[autorouter]

I imagine the problem is related to the exact form of the D+ signal. In theory, it's 'over +12V' when it is on, and 'zero' when it is off. But maybe the D+ signal only drops to say 0.5V to 1V, not zero.

The usual arrangement in electronics is to set some fairly high threshold, say 3V, and treat anything less than that as a definite zero. Using something like a Schmidt trigger circuit. This isn't advanced stuff, it's Chapter 1 of the logic circuits book.

If that hasn't been done, then the B2B may stay in the triggered state even if the D+ signal drops to 1V. That's how it looks to me, and would explain why they suggest using a switch in the D+ line.

Actually, probably a relay in the D+ line would solve it too, because a relay wouldn't switch on unless the voltage to the coil was fairly substantial, ie over about 6V.

But it's just poor design - which is why their alternative is to offer a refund.

 

[1967bowesj]

I imagine the problem is related to the exact form of the D+ signal. In theory, it's 'over +12V' when it is on, and 'zero' when it is off. But maybe the D+ signal only drops to say 0.5V to 1V, not zero.

The usual arrangement in electronics is to set some fairly high threshold, say 3V, and treat anything less than that as a definite zero. Using something like a Schmidt trigger circuit. This isn't advanced stuff, it's Chapter 1 of the logic circuits book.

If that hasn't been done, then the B2B may stay in the triggered state even if the D+ signal drops to 1V. That's how it looks to me, and would explain why they suggest using a switch in the D+ line.

Actually, probably a relay in the D+ line would solve it too, because a relay wouldn't switch on unless the voltage to the coil was fairly substantial, ie over about 6V.

But it's just poor design - which is why their alternative is to offer a refund.

autorouter you said it in the last sentence, poor design!

Why they even consider the trigger voltage should be below 12.7 say for standard battery/alternator I don’t know.

It’s set up now with a d+ switched relay so no issues now.
Will fit a manual switch in the d+ circuit ready so I can stop charging when it’s not needed.

 

[fred_jb]

I imagine the problem is related to the exact form of the D+ signal. In theory, it's 'over +12V' when it is on, and 'zero' when it is off. But maybe the D+ signal only drops to say 0.5V to 1V, not zero.

The usual arrangement in electronics is to set some fairly high threshold, say 3V, and treat anything less than that as a definite zero. Using something like a Schmidt trigger circuit. This isn't advanced stuff, it's Chapter 1 of the logic circuits book.

If that hasn't been done, then the B2B may stay in the triggered state even if the D+ signal drops to 1V. That's how it looks to me, and would explain why they suggest using a switch in the D+ line.

Actually, probably a relay in the D+ line would solve it too, because a relay wouldn't switch on unless the voltage to the coil was fairly substantial, ie over about 6V.

But it's just poor design - which is why their alternative is to offer a refund.

In my Ducato based van and probably many others the D+ signal is derived from the van's 12V via a relay, with the relay coil switched on by the actual engine on (0V) and ignition on (12V) signals which are present on a connector at the base of the vehicle's right side B pillar.

In this case the D+ is either connected to the vehicle's 12V supply when the relay is on, or just open circuit when it is off, so there is no residual voltage to confuse matters.

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[fred_jb]

autorouter you said it in the last sentence, poor design!

Why they even consider the trigger voltage should be below 12.7 say for standard battery/alternator I don’t know.

It’s set up now with a d+ switched relay so no issues now.
Will fit a manual switch in the d+ circuit ready so I can stop charging when it’s not needed.

I assume you will be using the switched D+ to turn a high current relay on to connect the starter battery feed to the DC-DC unit, as I have done? When this relay is off the unit no longer has a 12V source so is forced to stop charging.

As I think we have established, it does not seem sufficient to simply turn off the D+ signal to the DC-DC unit, as depending on the starter battery voltage it sees, it can continue charging regardless of whether the engine is running.

 

[1967bowesj]

I assume you will be using the switched D+ to turn a high current relay on to connect the starter battery feed to the DC-DC unit, as I have done? When this relay is off the unit no longer has a 12V source so is forced to stop charging.

As I think we have established, it does not seem sufficient to simply turn off the D+ signal to the DC-DC unit, as depending on the starter battery voltage it sees, it can continue charging regardless of whether the engine is running.

Yes after doing some research I found loads from a USA forum for dodge ram, Ducato in a new skin. They had been forced to use a switching relay which totally stops the power to the charger.

 

[fred_jb]

Yes after doing some research I found loads from a USA forum for dodge ram, Ducato in a new skin. They had been forced to use a switching relay which totally stops the power to the charger.

It would be interesting to read the USA stuff on this if you have a link as I am having some problems with mine.

I was out in the van today taking it for the software update which is hopefully going to prevent the auto gearbox from eating itself, and this was the first time with the starter battery feed relay fitted.

When I got back I checked in the app for both DC-DC and the shunt and they were both still showing about 45A of current flowing and the DC-DC was also still registering a voltage from the starter battery even though I verified that it was disconnected by the relay.

It seems like both devices are just continuing to display what readings were there before the relay operated. Resetting the shunt got it back to showing reality, but nothing I can do to either the app or the DC-DC is getting it to show the real situation.

I suspect that suddenly cutting the connection to the starter battery with the relay is leaving it unable to register the charging current dropping down so it is just showing the last readings before the relay operated.I am going to take the relay out of circuit for the time being and see what happens.

 

[fred_jb]

Just an update on this. I have bypassed the relay and run the engine briefly, and after removing then re-adding both devices in the app I got correct readings. The current from the starter battery dropped to zero almost immediately once the engine was off.

#baffled!

 

[1967bowesj]

Just an update on this. I have bypassed the relay and run the engine briefly, and after removing then re-adding both devices in the app I got correct readings. The current from the starter battery dropped to zero almost immediately once the engine was off.

#baffled!

I think it is the inconsistency that is the issue here, if it worked as it should then we would all be happy but it doesn’t and that’s what Renogy should acknowledge.

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