Leisure Battery Test

[icelander]

Nothing to do with this thread or even this Forum as I was checking my batteries because of a warning on UK Forum - but I notice that the vehicle battery vent hose is missing - so I got to thinking that with all this overcharging going on make sure yours is tight (and secure as I now need one)

[Terrytraveller]

Hi Jon,

 

I have mentioned before about the amount of water used which is just under a litre a year, bearing in mind the Array is feeding the battery all daylight hours, I was not surprised. It would be nice to know if anyone else with a solar panel needs to water the battery say twice a year, using nearly a litre of water a year.

 

Clive mentioned about 3 stage chargers, would you consider the solar panel to be equal in performance? Intermittently the panel should charge up to around 14.5 volts for a while, then as the sunlight disappears the charging rate will diminish, and the battery will rest for maybe eight to ten hours until sun up, the routine would then start over again. It’s just like being a pensioner !

 

I can confirm the regulator is connect correctly, fuses would blow and burning smells would issue forth otherwise - I think.

 

Regards Terry

 

PS I re-read the data sheet and you are right Jon, its constant voltage device,so its the current I should be concerned about. When the Array voltage has been high, around say 15 to 19 volts, I have never seen the current at the battery go below 400mA, voltage would have been 14.5 - 14.7 volts across the battery terminals.

 

 

Hi Rob,

 

Long time no hear – you’ve been away again haven’t you? Nearly marked you down as AWOL. Thanks for the vent reminder.

 

The leisure battery in a box below floor level is well ventilated and the battery has a vent hose fitted too. Although the battery bubbles away a little when under charge from the Array, its not a constant stream of bubbles. I have never detected moisture in the vent tube either, but then its under the MH with lots of air whizzing past it drying it off.

 

Regards Terry

 

[Brambles]

To answer the question about 3 state chargers, no the solar system you have is not as good. A three state charger I believe would drop the voltage down to 13.8 standby charge after fully charging. Having 14.4 volts or more on battery will just cause it to gas. Technically and realistically I do not see the need to always take a battey up to maximun charge possible for that extra 10% or whatever it is unless you absolutely need it and then it is debateable if you should fit an extra battery or larger capacity one.

If you have water loss and it falls below the plates then you lose the benifit of that extra charge anyway.

The spec says 14.4 volts for your solar charger and allowing for temperatire compensation I feel your voltages are a little high but from your last post about voltages it contradicts previous tests (I think).

Remember you are deep into this testing of your batteries, I am just picking up on certain points I understand and absorb and replying, I am not absorbing every little detail and every word you post so may well reply with something that conflicts with what you have already said.

Your project, just adding my pennies worth where I have time.

Now where did i put my asprins..LOL.

 

Jon.

[Terrytraveller]

Jon thanks again for your input, yes its a bit confusing as battery endurance tests were carried out on the Bench over the last 5 days, and Solar regulator to battery tests were carried out in situ in the MH in the same period.

 

The extreme results from the Array and regulator, where remembered from a year ago on the Med, when ambient temp was high and sun was overhead and very strong.

 

Have a rest now Jon - and many thanks.

 

Regards Terry

[Guest starspirit]

Most of the topic is over my head too but I still think that it is a very relevant and interesting thread on a subject that affects us all - battery capacity - and even if technical is well worth the effort that you techies are making

 

I have picked up quite a bit to store in my ever failing memory banks until required - hopefully NOT one cold dark wet night miles from anywhere.

 

Please do carry on the good work ye of superior knowledge but explanations in idiot proof would be appreciated where necessary please if possible.

 

Thanks.

[Brambles]

Non techie explanation,

 

Terry is charging around like a battery of hens. He has overheated in the Sun and is breaking rules set by regulators. The current situation, which to be specific, is of some gravity, is being watered down. However, I hear he has cooled down now but by watt I have not accumulated yet from the cable link to the mediteranean where he was over come by solar rays.

A Panel of Experts are being positive and may discharge him later. The negative side is he will have to be isolated for a while.

[Guest starspirit]

Oh dear, I do hope that high voltage emission does not flatten Terry's or Clive's capacity to absorb electrical energy to such a point that their plates collapse and their acid becomes too dilute to react with the lead in their pencils leading to a heavy escape of two explosive hydrogenous clouds of gas.

 

Or summat?

[Terrytraveller]

Hi Brambles and Starspirit,

 

All right boys – don’t get over excited – it’s only a forum – Hello Mother I’m on the Forum.

 

I must admit your remarks have made me chuckle. The more serious input has been useful too – don’t you think? I wonder if anyone has yet tried charging their battery fully and seeing how long it takes to discharge? Clive must be holding the Endurance test for batteries and Brambles for the one for being patient! I bet Jon has always got to the top of each hill he has climbed.

 

It will be interesting to see another myth hit the deck, old battery with new battery in parallel, if certain precautions are taken and some particular tests carried out, you should be able to determine whether a particular battery combination can be used, and will be interesting to some Forum readers. Most of our twelve volt batteries are made up from 6 x 2.2 volt cells, in theory fully charged they should issue 13.2 volts.

 

For Example ;-

 

1. Take any two batteries on the bench and fully charge.

 

2. Leave disconnected to rest for 24 hrs.

 

3. With a digital voltmeter check the terminal voltage on each battery is at least 12.7 – 12.8 volts, if one is lower say 11.5 volts don’t go further with this test. The battery with a low voltage reading may have an internal short on one cell, and ready to go bang!

 

4. Strap batteries in parallel and include a blade fuse holder connected with crimped spades between positive terminals of the batteries, and another one on the positive charger lead to the batteries.

 

5. Test one – no fuses in any fuse holders - see if current is leaking from one battery to another. i.e. one battery dragging the other down. Set the digital voltmeter to its 10 amp setting http://tinyurl.com/2d4luu , and insert probes into the fuse holder between the batteries. If the reading is only a few milliamps, I wouldn’t be worried, although a reading of zero would be ideal. It’s possible from this reading to determine which battery is taking power from the other if you have a reading greater than zero, by looking whether or not you have a negative or positive indication on the display.

 

6. Test two – to see if batteries are taking an equal charge from the Bench charger. Place a 10 amp fuse in the fuseholder connecting the batteries together, and with the meter still set on amperage reading, insert the meter probes in the fuse holder or crimped spades on the positive lead from the battery charger. Make a note of the reading in amps, this is the current going to both batteries.

Remove the meter leads and place a 10 amp fuse in the fuse holder, remove the fuse from the fuseholder between the batteries, ensure you are still set for a amperage reading on the meter and insert the meter probes into the fuse holder or crimped spades, take a reading . This reading is the current going to one battery, deduct one reading from the other and you will have the amperage going to each battery.

 

When I tried the this test on two batteries one new the other just over three years old, the charge going to both batteries was the same, so I am content that for the moment my batteries are still serviceable.

 

Regards Terry

 

[Brambles]

It is a myth.

If both batteries are serviceable, in other words are not faulty with a shorted or low resistance cell in one, high resistance cells are OK, then one battery will not drag the other down.

 

If you had a battery that had aged with partial shorting in a cell, then it not only drags itself down but other as well. So basically a 10 year old battery that is still holding charge will not drag down a brand new battery.

 

When drawing curent more will come from the battery with the lower resistance, normally the newer one, but as its charge falls the terminal voltage also falls so it is balance by the other battery supplying more current. It all balances out in the end to both batteries being balanced voltage wise.

 

Now comes the charging cycle. The older battery may require more volts so takes a bit longer to charge and lags behind the 'better' newer battery, but as you approach full charge it catches up but maybe never quite there unless you have a prolonged trickle charge. On discharging the new battey loses charge 1st until a balance is reached and down they go together again. As long as you are above, and from memory is 60% charge, permanent sulphation does not occur.

 

If you connect two batteries together in similar state of charge then current will not flow between them.

 

Now! In your vehicle, if your engine battery is charged to 14.4 volts from alternator its max charge is say 70 ot 80% .

Your Liesure battery is charged to 14.8 from solar panels so is say 90% to 100% charged. What happens when you start your engine and the split charge relay is closed and the two batteries are connected together and the engine battery and all the power circiuts connected will drag the Liesure battery down to 14.4 volts and 70 to 80% charge, losing all that solar power you spent £300 to get.

 

So to sumarise, if you are parked up at the supermarket for afternoon shopping in the midday sun (wait a mo, its afternoon!) then all that charge you are putting into your liesure battery is going to be lost. So all youhave done is evaporated some water off from your battery. By the time you get back to the campsite the sun has dropped and no longer helps charge the battery up. Darn I knew I should have got a bigger battery and not a solar panel! Ahhh! but Terry likes to stay in wild camping spots for days on end so is benificial. Agree, but I just start my engine and charge the battery for 15 mins using the diesel he used to overcome extra wind resistance and drag on his solar panels.

 

Oh heck, I am bored sitting here, nothing to do in this wild camping spot. Hey look dear, there is a man over there with a volt meter doing lots of tests on his batteries and solar panels, gosh I wished I had one so I had something to fiddle with and pass the time. LOL.

 

I really have waffled above for which I make no apologies, kind of tryiing to compete with terry.

P.S. Terry many thanks for what I regarded a very nice compliment.

[Terrytraveller]

Hi Jon,

 

Re - The fight between a Solar panel fully charged battery when married to a vehicle battery, via the split charge relay on starting and running the engine.

 

I haven't before now given it serious thought, but have in the back of my mind, seen it happen to me. The battery fully charged i.e endstopping on the MH internal gauge (really a multipurpose voltmeter), when switched to leisure battery at the beginning of a run.

 

By the time I've reached my destination with the engine switched off, the gauge is showing a lower battery capacity than before, even after a long run which is charging both vehicle and leisure batteries, and always is the same state of charge as the vehicle battery. So proving again you are quite right Jon - I would be bored if I was right all the time >:-)

 

Regards Terry

 

 

[Brambles]

Hi again Terry,

who says I am right, I am maybe just good at convincing you I am right when I am wrong all along.

Jon.

 

P.S. I have been involved in Autoelectronics and sytems all my career in development and design. I was always very much respected for my ability to problem solve and cut through the ice. Gosh! you would not think so from my waffling replies, but Batteries and charging sytems are quite complex with little quirky things that go on. I think Sterling and probably others make intelligent charging sytems for liesure batteries that stop things like the leisure battery discharging to the engine side of affairs.

At the end of the day though, do you need that extra charge. For example there is a chap who used to post a lot on all the forums that has a massive battery bank and powers mains fridges and goodness knows what else. Now for him 10% extra was a lot of power and well worth having. Also battery management was important because of the cost of replacing them all.

The plus side for solar panels though is really the ability to draw power during the day for TV or other items and not be drawing it all from your battery. It extends its life and even in the evening sun it makes a vast difference. So I am not knocking solar panels in my responses.

[Terrytraveller]

Hi Jon

 

Fully understand and appreciate your advice, and your ability to understand, and provide a sensible input to all our discussions. I could tell that you have a good background to automotive systems, and I have just enough numerancy skills to be convinced of your theories!

 

I've always been a practical sort of person, I was a field service engineer for a company manufacturing machines and systems which produced credit and ID cards etc.. for around 45 years.

 

R & D has proved beyond doubt that bumble bees are too heavy to fly, but they do - at least the ones around our house do, I suppose I am too heavy to fly but I did, so I like to have instruments around that substantiate any theory.

 

Anyway it's certainly been fun talking with you - and far better than painting the conservatory, which is what I should be doing.

 

Regards Terry

 

[Brambles]

Hi terry,

 

Yes, I love that one about bumble bees, its a very good analogy of what often happens in engineering.

 

Yep been fun. Won't be around next fortnight as away this weekend for Easter break...in Motorhome of course with family.

Jon.

 

 

[Terrytraveller]

Jon,

 

Hope the weather is kind to you, we go to Calais on 1st May for a couple of months touring Europe. So will probably catch you again before we go anyway.

 

Regards Terry