Battery discharging problems - any advise? (1 Viewer)

[Freedom Hunter]

We've just returned from 5 months cruising around Portugal. However, we hit a problem with our motorhome electrics. We have a 2010 Autocruise Starburst and fitted with a 120w solar panel (still the original battery). Until now the solar panel has always functioned fantastically and we have never had to worry about electric usage. For some reason, the battery charges fully over the day and as soon as evening approaches, within 10 minutes the battery totally discharges to zero - previously kept us easily supplied with electric overnight. We've removed the fully charged battery to our garage to test it and it is behaving as it should - retaining the charge as it used to do - for days. We've checked the Sargent unit and with everything in the motorhome switched off, it said it was only pulling 0.1amp - which is fine. We've cleaned the battery contacts and they are fine. We're assuming the battery is getting old and the cells breaking down, so maybe needs replacing. How long do batteries usually last? Any ideas out their would be gratefully received.......... Caroline

 

[TheBig1]

what you are reading is a floating voltage and the battery is likely now dead. Put it under load and it has no capacity. depending on the quality and the technology used batteries are good for 400-500 charging cycles. In an ideal environment a battery can last 10 years, but you rarely see that so on average 5 years for a leisure battery

 

[tinkering]

Six years if you are lucky

May I suggest you take the battery to a garage ,they will be able to test it in a few minutes

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[Techno]

How long is a piece of string.
Every battery has a maximum number of discharge recharge cycles but this is often abused by over discharging and late recharging. So it could be a year or several years.

 

[Techno]

If you disconnect the battery completely and measure the voltage it will reveal all.
12.7 volts is fully charged
12 volts is flat
below 12 volts is an incremental measurement of Fubar'd

 

[andy63]

I have a feeling that what you have been seeing as a healthy battery is your solar panel voltage.. if your battery is dead after 10 min on load it sounds like its had it.... when you say zero what do you mean... it will have some measurable voltage..
andy

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[Freedom Hunter]

Many thanks for all your advise - fantastic! - well perhaps not, as it looks like a new battery is needed - it is as we thought. many, many thanks everyone....
ps - any recommendations for a new battery, i know there are currently 3 types.....

 

[Techno]

Many thanks for all your advise - fantastic! - well perhaps not, as it looks like a new battery is needed - it is as we thought. many, many thanks everyone....
ps - any recommendations for a new battery, i know there are currently 3 types.....

Depends on how much space you have? Is it crammed in, under a front seat or plenty of room.

 

[Techno]

If space is not an issue I recommend any DC31 or equivalent like this
http://www.ebay.co.uk/itm/XV125MF-P...220160?hash=item3f234d7bc0:g:1DwAAMXQs6FRSEDD

Alternative of same battery and whom I normally use

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[pappajohn]

What everyones missed so far is........

We've removed the fully charged battery to our garage to test it and it is behaving as it should - retaining the charge as it used to do - for days.

If it was indeed simply solar/charger surface voltage while on the van why is it holding charge on the bench.
If the battery was completely cabbaged it would self discharge in a very short time.....or wouldnt charge at all.
I would suggest the blocking diodes on the panel have failed allowing current to flow back to the panel at night....which is when the problem arises.

 

[Techno]

If it was indeed simply solar/charger surface voltage while on the van why is it holding charge on the bench.

That read to me like attached to a battery charger

 

[pappajohn]

That read to me like attached to a battery charger

Possibly Andy, never thought of it that way.

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[Freedom Hunter]

Many thanks Andy (Techno) for your battery recommendations - they look good and a great price!
Regarding pappajohn's analysis - it seems good sense and as i've said it seems strange to me that on the bench the battery is holding it's charge - and the fault may actually be in the van. "I would suggest the blocking diodes on the panel have failed allowing current to flow back to the panel at night....which is when the problem arises." I do not quite understand this - being totally non-technical, just logical! I'm assuming that by "panel" you mean the motorhome control panel being faulty? Or are these diodes actually in the battery - sorry, as i say - none technical! My logic says that during the day and the electic is flowing 'in' to the panel/diodes and at night when there is no incoming flow, the electric reverses and flows out? Surely this is all controlled by the Sargent unit? Perhaps this may have acquired a fault, as at the end of the day i think this controls all the electric flow, whether input or output.
I a loathe to buy a new battery if this is not the fault - though it is pretty old and has been well used - away for at least 5 months every year. My next thoughts are - who would I get to look at the van - just a motorhome mechanic or perhaps a mobile electronics expert?
But many thanks again ......

 

[Freedom Hunter]

....another thought - the Sargent unit is only showing showing a 0.1 drainage. When we disconnected the solar charging the Sargent slipped12.8 to 12.7 to 12.6 very quickly.....

 

[DavidG58]

I reckon I am pretty much with you on technical ability, but I think the reference to diodes is in the solar controller, to stop the battery sending power back to the panel in the dark

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[Techno]

The 0.1 drainage could be the battery itself due to a cell failure. Batteries comprise of 6 cells and if one fails the voltage when disconnected will drop to around 10.6

 

[pappajohn]

I'm assuming that by "panel" you mean the motorhome control panel being faulty? Or are these diodes actually in the battery -

The diodes are part of the solar panel and prevent electrical current being sent back to the panel from the battery when the sun dont shine.
The crystal cells on the panel will absorb any current and eventually flatten your battery.

 

[Freedom Hunter]

Many thanks! Bit of controversy - are the diodes within the actual solar panel or the solar panel controller? Also, surely the Sargent unit should control the flows, so that this should never happen?

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[andy63]

Do you have a dedicated solar charge controller in the system or is your panel wired through a Sargent built in charge controller..
Only asking because of John's point about the panel blocking diodes... I'm sure my mppt charge controller has that function built into it to stop reverse current... so in my case I'm sure the controller and panel diodes would both have to be faulty for a reverse current to flow...
Andy.

 

[shawn&emma]

The diodes are part of the solar panel and prevent electrical current being sent back to the panel from the battery when the sun dont shine.
The crystal cells on the panel will absorb any current and eventually flatten your battery.

As an aside to the original thread. How would I know if my solar panels have blocking diodes, is it just normal practice to do this? I am guessing that they do because my panels feed straight to the batteries and don't lose overnight. There was a little connection box on the back of the panel, should have had a nosey but didn't.



Details On Solar Panel
Dimensions - 1250 x 570 x 30mm. Longer, narrower, and 3% more efficient than poly.
Specifications
Open-circuit voltage (Voc) Av 22.1V, sd 0.3
Voltage at maximum power (Vmp) Av 17.9V, sd 0.2
Short-circuit current (Isc) Av 5.56A, sd 0.01
Current at maximum power (Imp) Av 5.12A
Maximum power at STC (Wp) 100W ±3%
Operating temperature -40oC to +85oC
Maximum system voltage 600Vdc
Power tolerance ±3%

Shawn

 

[andy63]

As an aside to the original thread. How would I know if my solar panels have blocking diodes, is it just normal practice to do this? I am guessing that they do because my panels feed straight to the batteries and don't lose overnight. There was a little connection box on the back of the panel, should have had a nosey but didn't.



Details On Solar Panel
Dimensions - 1250 x 570 x 30mm. Longer, narrower, and 3% more efficient than poly.
Specifications
Open-circuit voltage (Voc) Av 22.1V, sd 0.3
Voltage at maximum power (Vmp) Av 17.9V, sd 0.2
Short-circuit current (Isc) Av 5.56A, sd 0.01
Current at maximum power (Imp) Av 5.12A
Maximum power at STC (Wp) 100W ±3%
Operating temperature -40oC to +85oC
Maximum system voltage 600Vdc
Power tolerance ±3%

Shawn

Yep that little box most probably has the diodes in it... mine does and im assuming that's what they are ...but I'm sure my charge controller has reverse polarity and reverse current fiction as well...
Waiting for someone to confirm that's normal or have I picked up incorrectly on that...
As an aside it's unusual for your panel to feed directly to the batteries without a charge controller... unless it's a small panel...say 40w or less..
Andy

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[shawn&emma]

Yep that little box most probably has the diodes in it... mine does and im assuming that's what they are ...but I'm sure my charge controller has reverse polarity and reverse current fiction as well...
Waiting for someone to confirm that's normal or have I picked up incorrectly on that...
As an aside it's unusual for your panel to feed directly to the batteries without a charge controller... unless it's a small panel...say 40w or less..
Andy

Hello @andy63 Hope you are well and still enjoying life. We met a while ago/last August at a small meet on a CL near Inverness.

I run a wind turbine as well as 2 100w solar panels and the research I did at the time suggested I should run all direct to the batteries. The controller then monitors the batteries and any excess is distributed to a couple of resistors.

 

[andy63]

Hi.. yes that will have been at brin..
Hope all well with you..
I'm not familiar with that set up...I thought the controllers were installed between charging source and battery...and regulated the charging current to suit...
Hope we meet again somewhere sometime...
Andy.

 

[ShiftZZ]

Is this about right?
Broken Link Removed

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[Don Quixote]

Please do not discharge your battery or batteries past 12.2volts as you are at the 50% mark and will start to destroy them. Do this a number of times and you will be replacing them.

 

[berni109]

Does anyone know what charging characteristics a calcium based battery requires?

 

[andy63]

Does anyone know what charging characteristics a calcium based battery requires?

I think they are just a type of lead acid battery... They require a higher charging voltage...ie up to 14.8v..

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[DBK]

Hello @andy63 Hope you are well and still enjoying life. We met a while ago/last August at a small meet on a CL near Inverness.

I run a wind turbine as well as 2 100w solar panels and the research I did at the time suggested I should run all direct to the batteries. The controller then monitors the batteries and any excess is distributed to a couple of resistors.

More thread hijack I'm afraid but if I understand that correctly you have a pretty inefficient setup. Solar panels work best when allowed to run at their optimum voltage, which for a typical MH panel is around 18 volts. Coupling them across a battery drags the voltage down with negligible increase in current to compensate. A good MPPT controller is what you need.

For the wind turbine I guess coupling across the batteries would be correct, assuming it is a 12 volt generator, but this does not apply to solar although it can certainly be done if you accept the reduction in output.

 

[berni109]

@Techno you were suggesting calcium based battery earlier in the thread but where do you get the extra charging volts from?
Need to change mine but want to be sure before ordering.
Thx.

 

[Techno]

Just set the charger to wet lead acid

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