Alternator charging light staying on. Renogy DCC50S

[fred_jb]

You know what Fred, but I've got that same shunt to fit! I bought it all in May, but with one thing and another, I've not the time to fit it all.

I've got the DCDC50S fitted to mine now, and was just wanting to see it working before I fit the shunt and lithium.
with the engine and ignition off, does your DCDC50S charge from the starter battery? (Far left hand LED lit up red) Mine does, albeit only drawing small current, until the starter battery drops to 12.6V. It seems strange to deplete charge from the starter battery.

Is yours a smart alternator?

Hoping you can help me out here!

There is a bit of a problem with the terminogy used with these kind of units. When they refer to an alternator input it is not a direct connection to the alternator, instead it is a connection to the starter battery +ve which in turn connects to the alternator. So, if it says it is charging from the alternator, in reality it is charging from the starter battery. Unless you connect a proper D+ signal it has no way of knowing if the alternator is actually charging the starter battery and so has to infer this from the level of the starter battery voltage which can obviously be misinterpreted in various scenarios. This can lead to charge being taken out of the starter battery when the alternator is not providing charge to it which is what seems to happening with yours.

My van has a smart alternator and I have connected the D+ signal to the B2B, but would have done so even if it wasn't a smart alternator. As far as I can tell the B2B now only operates to take charge from the starter battery and send it to the leisure battery if the engine is actually running, which is what I want.

Interestingly if the leisure battery is fully charged and you have solar panels connected it seems that it will use the solar input to charge the starter battery instead, and I think I saw this happening the other day. To me this raises the question of how suitable this charging regime is for the AGM starter battery as you can only specify battery type for the leisure battery and I have that set to lithium.

These are my current readouts, with the weak winter sunshine only providing about 45W from my 280W solar panel array!

I have disabled the Electroblock trickle charging of the starter battery, so am relying on the Ablemail unit to keep it topped up, though that, the B2B and the shunt seem to disagree slightly on the voltage reading. The Ablemail unit basically passes charge to the starter battery if the leisure battery is above 13V and the starter battery is below 12.5V.

 

[growly_bear]

My van has a smart alternator and I have connected the D+ signal to the B2B, but would have done so even if it wasn't a smart alternator. As far as I can tell the B2B now only operates to take charge from the starter battery and send it to the leisure battery if the engine is actually running, which is what I want.

Thanks again. So can you confirm that as soon as you switch off the engine, the charge light extinguishes immediately? If it does, I'll fit the DCDC50S D+ to the EBL.

I read in my manual, that yes the starter battery is charged once the leisure battery is deemed to be fully charged, and so no need to have an alternative method of keeping the starter battery charged. However, I would like to switch off the lithium at 80% when not being used, but this will confuse the DCDC50S! Although reducing the float voltage could go some way to helping...

I'll send a "Case" to Renogy asking what the battery type is for the starter battery for when the solar is charging

 

[fred_jb]

Thanks again. So can you confirm that as soon as you switch off the engine, the charge light extinguishes immediately? If it does, I'll fit the DCDC50S D+ to the EBL.

I read in my manual, that yes the starter battery is charged once the leisure battery is deemed to be fully charged, and so no need to have an alternative method of keeping the starter battery charged. However, I would like to switch off the lithium at 80% when not being used, but this will confuse the DCDC50S! Although reducing the float voltage could go some way to helping...

I'll send a "Case" to Renogy asking what the battery type is for the starter battery for when the solar is charging

Thanks for raising the case with Renogy. It will be interesting to hear what they say about that.

Yesterday I moved my switch for the D+ into the centre console to be accessible while driving and looked in the app at what happened when switching on and off. At first it didn't seem to stop charging immediately, but that might be just lag in the app. I will try again today and take the cover off the rear of the seat so that I can see the lights on the unit.

While investigating if my switch was working properly I wasn't sure if the voltages were correct as something else the converters had connected to the D+ seemed to be putting 2-3 volts on the line when I expected it to be zero. More investigation required today!

 

[growly_bear]

Thanks for raising the case with Renogy. It will be interesting to hear what they say about that.

Yesterday I moved my switch for the D+ into the centre console to be accessible while driving and looked in the app at what happened when switching on and off. At first it didn't seem to stop charging immediately, but that might be just lag in the app. I will try again today and take the cover off the rear of the seat so that I can see the lights on the unit.

While investigating if my switch was working properly I wasn't sure if the voltages were correct as something else the converters had connected to the D+ seemed to be putting 2-3 volts on the line when I expected it to be zero. More investigation required today!

I'll be sure to report back, although it does sometimes take a few messages each way!

Thanks for the trouble which you are going to, and hoping that you find it useful too.

There is always something to fathom out! I've just ordered a clamp meter to add to my toolkit.

 

[fred_jb]

I'll be sure to report back, although it does sometimes take a few messages each way!

Thanks for the trouble which you are going to, and hoping that you find it useful too.

There is always something to fathom out! I've just ordered a clamp meter to add to my toolkit.

No problem, and as you say it is useful to me too.

I have just done some more testing of the charging behaviour. I didn't write anything down, so I'm relying on my sometimes defective memory, but the following is more or less what I am seeing:

I watched the red light and also monitored charging current on the One Core display. Initially I had the D+ switched off when I started the engine, but the red light came on and the display showed a fairly high level of charging so I think it was happily working in non-Euro6 mode. However, the current then dropped right down though the red light stayed on, which I suspect was the Euro6 alternator going into energy saving mode and dropping its output voltage. If I then switched on the D+ signal the current ramped back up to 50A. If I switched it off the current dropped right down to more or less zero but the red light didn't go off, though when I went through the cycle again the red light did go off when the D+ was switched off.

My conclusion is that the charger will always work if it sees enough voltage at the starter battery regardless of whether the D+ is applied which I guess it what you would expect as it is designed to work with either type of alternator and with or without a D+ signal. However once the Euro6 alternator behaviour kicks in, which is not immediate, it then becomes responsive to the D+ signal. The red light seems a little random at times, but looking at the charging current in the app confirms that the charging goes on and off as expected with the D+ signal once the engine has been running long enough for the Euro6 alternator to do its thing.

I hope that helps.

Regarding turning off charging at 80%, I know this is the recommendation for maximum life for lots of lithium battery types, including those in EVs, but I have also read that it only makes a marginal difference, so I'm not sure what to believe on this. It would be interesting to see what the B2B makes of this if you turn off accepting charge in the battery's BMS. I suppose it depends on how this is accomplished by the BMS. I could imagine it must be an physical electronic switch as just changing to a fully charged status would not necessarily stop devices sending charge to it. That would probably look to the B2B as if the battery had been disconnected, though if the BMS was still allowing outgoing current then the B2B would still be able to sense the leisure battery voltage, which might confuse it. I suppose in the worst case it might damage the B2B, but hopefully it has protection against this sort of thing. I think if I decide to limit charging of the battery I will do it with the D+ switch and the breaker switch I put in the solar panel wiring.

^{_{Subscribers  do not see these advertisements}}

 

[growly_bear]

My conclusion is that the charger will always work if it sees enough voltage at the starter battery regardless of whether the D+ is applied which I guess it what you would expect as it is designed to work with either type of alternator and with or without a D+ signal. However once the Euro6 alternator behaviour kicks in, which is not immediate, it then becomes responsive to the D+ signal. The red light seems a little random at times, but looking at the charging current in the app confirms that the charging goes on and off as expected with the D+ signal once the engine has been running long enough for the Euro6 alternator to do its thing.

Thanks Fred. This makes complete sense to me, and my dumb alternator is mirroring what you see with your D+ connected.

Regarding turning off charging at 80%, I know this is the recommendation for maximum life for lots of lithium battery types, including those in EVs, but I have also read that it only makes a marginal difference, so I'm not sure what to believe on this. It would be interesting to see what the B2B makes of this if you turn off accepting charge in the battery's BMS. I suppose it depends on how this is accomplished by the BMS. I could imagine it must be an physical electronic switch as just changing to a fully charged status would not necessarily stop devices sending charge to it. That would probably look to the B2B as if the battery had been disconnected, though if the BMS was still allowing outgoing current then the B2B would still be able to sense the leisure battery voltage, which might confuse it. I suppose in the worst case it might damage the B2B, but hopefully it has protection against this sort of thing. I think if I decide to limit charging of the battery I will do it with the D+ switch and the breaker switch I put in the solar panel

I've also read the same re 80% and it only having a limited affect on longevity.

I did pull the leisure battery fuse and the DCDC50S came up with a low battery error, so I'll not be able to turn the BMS off. On my Jiabaida JBD BMS I can turn it off with a mechanical switch or use the app software. I, like you would think that there would be protection in place to protect the DCDC50S in the event of a leisure battery fuse blowing.

Another thought re keeping the battery connected would be that when it is fully charged that current would be diverted from solar to the starter battery and then not needing a starter battery maintenance charger...

Lots to think about.

 

[fred_jb]

Lots to think about.

Definitely - my latest unforeseen issue is losing the mains indicator light on the LT100 control panel. This was because I completely disconnected the mains supply from the EBL to avoid a quite large current drain from the internal EBL circuitry after I removed the 20A fuse which lets it charge the leisure battery. I am now buying a little module which drives an LED from a mains supply and will patch that into the system to get the mains indicator working again.

ECP4-S - Ecopac ECP4-ILP Series LED Driver 4W 350mA – 700mA

Constant current designIP66 ratedProtections: Short circuit/ Overload/ Over temp.Input Voltage: 100 – 240VACCooling by free air convectionLow cost, high reliabilityOutput Power: 4WCompact and light-weight plastic caseWorking Temperature: 0°C to +45°C3 year warrantyMore Information Manufacturer...

www.easy-controlgear.com