Jump to content

Faulty solar advice needed, over charge.


Recommended Posts

The 12.4-12.5v seems a reasonable level to me but it is worth emphasising, that this is with no or minimal load.  You are going to see lower voltages if you measure with everything switched  on.

 

What I would do, and this is quite difficult, is nothing but observe.  It might be that every time you alter a setting then the controller goes to the higher equalisation phase.  My controller does this for a couple of hours every month.  I have never seen it happen but the display logs the maximum voltage and it reached 15.1 V.  If you leave it for 24hrs then perhaps the controller will go through this stage a revert back to a float voltage of around, 13.8v.  

It is also worth, as suggested,  checking the  voltage at the battery it might tell a slightly different story.  We had an incident about 3 weeks ago we arrived on a non ehu site on Thursday evening.  I assumed that battery would be fully charged, but as soon as anything was switched on everything was flashing low voltage warning.  I assumed that a wire had come off the controller but it was fine.  I checked the voltage at the battery, 12.8v there was obviously a loose connection somewhere on the output from the battery I disconnected reattached some connectors and the problem seems to have resolved itself, so next 3 nights no problem, as were 4 nights over Easter and 2 nights this weekend, but I would say a basic multimeter is worth keeping in a caravan. 

 

Finally if it turns out that the Truma controller is faulty.  I am not sure I would rush out and buy a replacement Truma controller.  It is a fairly generic 30 quid controller but I bet the Truma don’t charge £33.99 for it?

Truma alternative

Edited by fred
Link to post
Share on other sites

It might be showing something up to 15V but what it does not show is how much current is flowing. As solar panels have limited current capability it may well be that the control box is putting out 15V but at very severely limited current, indeed it may actually be charging in constant current mode at a few tens of milliamps. Short of putting an ammeter in series you have no way of knowing.

When we first got our U4 Seville I saw the voltage - ISTR - at something like 15.6V. I contacted the manufacturer who said this is quite normal. I have never seen it that high since.

2018 Passat B8 Estate 150GT TDi150 towing a 2018 Bailey Unicorn S4 Seville

Link to post
Share on other sites

It's unlikely that the controller is at fault, IMO the biggest problem here is information overload that the OP doesn't understand.

 

Just looking at a voltage and panicking isn't a good thing.

 

I'm not trying to be derogatory or patronising but sometimes more information isn't helpful if you don't know what it means.

 

Understanding how batteries, charging systems and especially solar systems perform is a bit of a black art and so you really need to know what is happening and to understand why it happens and what causes it.

 

Sometimes then confusion is then compounded by well meaning but wrong advice

Edited by matelodave
  • Like 1

2018 S-Max Titanium 2. 0 Tdci (177. 54bhp,180ps,132kw) Powershift + 2015 Unicorn III Cadz, Ventura Marlin porch awning

Link to post
Share on other sites

Years ago when I first trained the Lucas 2 bobbin regulator would deliver 16 volt when open circuit, although batteries and chargers have changed over the years, the basic chemical reaction is the same, so below 80% charged one can bang in the charge, and after 80% it has to be much slower.

 

What has changed it the ability to replace water, in the old days both wet and gel batteries could be topped up, if there was a massive over charge it could buckle the plates and/or cause active material to fall of the plates, but a 4 amp charger was unlikely to damage a battery.

 

However with sealed batteries one has to be very careful not to over charge or it will dry out, early sealed were really wet batteries with a large amount of water in them and venting designed to capture water and return it, worked OK if battery kept cool, so chemicals used to make the lead stick to the plate was reduced which also reduced gassing.

 

However with the valve regulated lead acid (VRLA) or absorbed glass mat (AGM) only just enough electrolyte is used, unlikely the simple sealed breaking the case and acid did not pour out,  and they can be used at any angle. Temperature is important and with cars the battery is no longer in the engine compartment as can get too warm, it has moved to the boot.

 

The chargers use different methods, some pulse, and measure volt decay, some float charge only, and some match current and voltage. So a typical car charger has gone from 4, 6, 8, 10, and 12 amp, with cells you could top up, down to 3.8 amp max with VRLA and the charger is designed to drop charge rate so once fully charged the max rate is 0.8 amp mine has zero, 0.1 or 0.8 amp once battery has been sensed as charged.

 

With a larger charger only simple way is a float charge, 13.2 volt to 13.8 volt the actual voltage depends on temperature and use, so as stand by 13.2 and in a car 13.8 the aim is to fully recharge without over charging, my old stair lift would slightly over charge battery, and as long as used daily not a problem, but if left unused it would dry out battery.

 

Be it a narrow boat or caravan charging and using battery at the same time is a problem, with a stage charger it uses the current drawn to know when to drop into final stage, if the lights are on, then it may never drop into final stage and so over charge the battery.

 

So there is a certain amount of compromise, cars use a computer to work out what is needed, as does your laptop, measuring power used and replaced, and some solar chargers also have a terminal to supply 12 volt to aux circuits so it can actually know what is being used, although that can't include motor mover, but to assume in morning it needs to recharge battery and later only float battery is a good compromise.

 

However as the user it does not help, I know a good battery left on charge with Lidi battery charger will in time drop to 12.9 volts, at 12.8 volts it restarts charging, it takes it to 14.4 volts very quickly, then it switches off again, so 9 times out of 10 when you look it shows 12.9 volts. Each charger has it's own system, and failings, the Lidi charger with a poor battery may never turn off. 

Link to post
Share on other sites
10 hours ago, Woodentop said:

It might be showing something up to 15V but what it does not show is how much current is flowing. As solar panels have limited current capability it may well be that the control box is putting out 15V but at very severely limited current, indeed it may actually be charging in constant current mode at a few tens of milliamps. Short of putting an ammeter in series you have no way of knowing.

When we first got our U4 Seville I saw the voltage - ISTR - at something like 15.6V. I contacted the manufacturer who said this is quite normal. I have never seen it that high since.

 

This is where Swift command comes in, I can see what my solar panel current is, its typically under 5amps.

  • Like 1
Link to post
Share on other sites

Before I had a sophisticated meter integrated with my solar controller, I used one of these very useful Amp measuring gadgets inserted into the fuse holder of the positive lead back to the battery.

 

https://cpc.farnell.com/tenma/ten01046/current-tester-automotive-std/dp/IN04874?st=automotive current testers

 

It is particularly neat as the fuse is moved and reinserted in the probe, like that the circuit works as normal and you only need to flick its switch on when interested in measuring the current.

Note these come in two different modes to suit the standard and mini blade fuse, so you buy the one required.

 

Knowing the current the solar system is pushing out, and in this case if the controller is regulating things is both useful and interesting. Once purchased the gadget can be a useful item for checking things on the caravan and car.

Edited by JTQ
Link to post
Share on other sites

They are useful I have both sizes, but they are battery powered, I had to replace one recently....

 

 

Link to post
Share on other sites

Just to let everyone know that our four nights away went well. Batteries were charges fully by lunch time, I think the Alde heating uses more power than the tv,  it was cold, I think there was a bit of snow around (Abergavenny).  The heating seems to go on and off a lot at night despite being set to 13c. (night mode). Used the tv during the morning and at night.  We didn't notice low volts, only low volts (12.6) in the morning due to heating on (Ithink). I noticed maximum amps was 4.1 and maximum volts 15 which then drop to 13.7.

  • Like 1

Grass growing, Mercedes E320 CDI driving, Bailey tugging caravanner.

Link to post
Share on other sites
On 29/04/2019 at 07:47, fred said:

The 12.4-12.5v seems a reasonable level to me but it is worth emphasising, that this is with no or minimal load.  You are going to see lower voltages if you measure with everything switched  on.

 

What I would do, and this is quite difficult, is nothing but observe.  It might be that every time you alter a setting then the controller goes to the higher equalisation phase.  My controller does this for a couple of hours every month.  I have never seen it happen but the display logs the maximum voltage and it reached 15.1 V.  If you leave it for 24hrs then perhaps the controller will go through this stage a revert back to a float voltage of around, 13.8v.  

It is also worth, as suggested,  checking the  voltage at the battery it might tell a slightly different story.  We had an incident about 3 weeks ago we arrived on a non ehu site on Thursday evening.  I assumed that battery would be fully charged, but as soon as anything was switched on everything was flashing low voltage warning.  I assumed that a wire had come off the controller but it was fine.  I checked the voltage at the battery, 12.8v there was obviously a loose connection somewhere on the output from the battery I disconnected reattached some connectors and the problem seems to have resolved itself, so next 3 nights no problem, as were 4 nights over Easter and 2 nights this weekend, but I would say a basic multimeter is worth keeping in a caravan. 

 

Finally if it turns out that the Truma controller is faulty.  I am not sure I would rush out and buy a replacement Truma controller.  It is a fairly generic 30 quid controller but I bet the Truma don’t charge £33.99 for it?

Truma alternative

Just had the weekend away my mates and my Truma controllers failed on our unicorn 3's. We will not be replacing with Truma units as it seems they are unreliable.

Link to post
Share on other sites
27 minutes ago, Xl125 said:

Just had the weekend away my mates and my Truma controllers failed on our unicorn 3's. We will not be replacing with Truma units as it seems they are unreliable.

I have to say than mines been fine on my 2015 Cadiz, however if I was going to replace it I'd be getting a Victron.

 

Some of them can be connected to your phone via Bluetooth, so you can monitor what is going on (if you like to do that sort of thing) They are also MPPT rather than PWM which should give you better performance when the weather isn't so good.

 

See here https://www.victronenergy.com/solar-charge-controllers/mppt7510

2018 S-Max Titanium 2. 0 Tdci (177. 54bhp,180ps,132kw) Powershift + 2015 Unicorn III Cadz, Ventura Marlin porch awning

Link to post
Share on other sites

I would have a great deal more faith in buying  a Victron, a highly regarded brand in this field.

  • Thanks 1
Link to post
Share on other sites

I am a very satisfied Photonic Universe customer.  Victron kit is pretty expensive, and I was working to a reasonable budget.  I upgraded my boat from 2x45W Solara panels with a Morningstar 10A PWM controller to 2x100 panels +10A MPPT controller all from Photonic for £500.  

Larry from Essex

2019 Bailey Unicorn Cabrera 2017 Kuga 2. 0 TDCi 150

Link to post
Share on other sites
33 minutes ago, Guzzilazz said:

  I upgraded my boat from 2x45W Solara panels with a Morningstar 10A PWM controller to 2x100 panels +10A MPPT controller all from for £500.  

 

 200Watts with 10A controller, so the boat has a 24 Volt system, not our12 VDC?

Link to post
Share on other sites

Typo...20A controller... 12 V

Larry from Essex

2019 Bailey Unicorn Cabrera 2017 Kuga 2. 0 TDCi 150

Link to post
Share on other sites

My PWM controller had the battery fully charged by 8 50 this morning.  If I spent £120 on a mppt controller do think I would be able to get this time down to 8 30am ?

Link to post
Share on other sites
19 hours ago, fred said:

My PWM controller had the battery fully charged by 8 50 this morning.  If I spent £120 on a mppt controller do think I would be able to get this time down to 8 30am ?

Not worth the upgrade IMHO... Although you could get an MPPT for much less than £120... Photonic Universe who supplied my kit have a 10A MPPT for £59.99... The 10A equivalent of mine is £69.99

Larry from Essex

2019 Bailey Unicorn Cabrera 2017 Kuga 2. 0 TDCi 150

Link to post
Share on other sites

I must admit that my tongue was firmly in my cheek when I made my comment.  I do however have serious doubts over the real world as opposed to theoretical  benefits of mppt.  There are advantages of mppt for large installation but for a caravan I’m not sure.  Until recently I had a 150W panel on the roof.  Recently I have supplemented this with a semi flexible 120W panel.  The cost of the panel was £92.00 add in another £20 for a tube of adhesive and a couple of mc4 branch connectors.  So for £110 I have increased my solar capacity by 80% which strikes me as pretty cost effective.  

  • Like 1
Link to post
Share on other sites

You generally get the MPPT benefit when you series connect multiple panels, you see voltages at the panels of high 30's low 40's which means you have half the current, and the controller will then "transform" it down... although it's not a wound transformer...

  • Thanks 1

Larry from Essex

2019 Bailey Unicorn Cabrera 2017 Kuga 2. 0 TDCi 150

Link to post
Share on other sites
41 minutes ago, Guzzilazz said:

You generally get the MPPT benefit when you series connect multiple panels, you see voltages at the panels of high 30's low 40's which means you have half the current, and the controller will then "transform" it down... although it's not a wound transformer...

 

In our typical need to enhance the low light performance, this upping the solar voltage by wiring in series or buying  a panel with an inherently higher peak performance voltage, is so often missed when adopting MPPT controllers is recommended.

 

I suggest that during good summer lighting conditions, most of us don't need to  gather more, we are topped well before the sun wanes; chasing performance in poorer lighting is IMO by far the most rewarding goal.

 

 

Edited by JTQ
  • Like 1
Link to post
Share on other sites
2 minutes ago, JTQ said:

 

I our typical need to enhance the low light performance, this upping the solar voltage by wiring in series or buying  panel with an inherently higher peak performance voltage, is so often missed when adopting MPPT controllers is recommended.

 

I suggest that during good summer lighting conditions, most of us don't need to  gather more, we are topped well before the sun wanes; chasing performance in poorer lighting is IMO by far the most rewarding goal.

Absolutely right... My MPPT experience is not on the Caravan, but the boat.  I had 2x45W parallel panels feeding initially a Morningstar controller, but I couldn't easily monitor the performance, other than by lifting cushions and seats and stuffing my head into the bilge with a multimeter.  The original controller was over £80, so I replaced with a  dual output Chinese PWM, which had an RJ45 connected display.  The dual output was useless, since the VSR on the alternator side effectively paralleled the domestic and engine bank, but the display gave loads of useful info.

 

Fast forward to end of 2016 and Southampton Boatshow, where Photonic were exhibiting and I got 2x 100W panels, MPPT controller and meter for £500 (£300 less than the first installation!)  Installed in Oct 2016, I've not had the charger connected to the domestic bank at all, and we can go more than a week off grid... Needs are somewhat simpler, because it's mainly the fridge (compressor 0.8A per hr consumption) and a few LED lights.

Larry from Essex

2019 Bailey Unicorn Cabrera 2017 Kuga 2. 0 TDCi 150

Link to post
Share on other sites

I don’t doubt that a MPPT controller has theoretical advantages and by connecting panels in series means that the minimum voltage will be reached earlier than, than with a single panel.  The question is at those low light levels is a useful level of charge is being put into the battery?   If for example a mppt controller start to charge 30 minutes earlier than a PWM controller but only puts 0.1Ah into the battery is it meaningful?   

I am not against mppt controllers I am against the sort of reply  I have seen which is basically.  

OP I’ve got a 10 solar panel stuck in the front window of the van and in January it isn’t charging the battery.   Someone invariably answers with you need to get is a mppt controller.  I’ve exaggerated the scenario a little but I’m sure you get my point.  

  • Like 1
Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...