Controversial! Why Solar can damage your batteries! (1 Viewer)

[jonandshell]

Following on from another thread where I mentioned that we don't have solar panels, here is my reasoning-

In my industry, our electrically powered machines are run by good old open lead acid traction batteries. Traction monoblocs are my chosen method of running our habitation electrics.
All the batteries supplied to our customers are covered by a manufacturers warranty of 5 years. This is not a warranty of averages, this is a warranty based on 250 cycles a year at a 6 hour discharge rate. The battery useage can be easily monitored by means of downloading the cycle data from the chargers.
Now, the number one reason for warranty rejection by our suppliers is 'customer opportune charging'. This means the battery user is putting the battery on charge for short periods, often on breaks or between shifts, in an effort to top up the battery charge.
The result of this 'opportune charging' is that the battery capacity gradually falls and thus more opportune charging is applied in an effort to complete the days work. This trend destroys the battery cells through gradual sulphation.

Here is the explanation-

Sulfation occurs when a lead acid battery is deprived of a full charge. This is common with starter batteries in cars driven in the city with load-hungry accessories. A motor in idle or at low speed cannot charge the battery sufficiently.

Electric wheelchairs have a similar problem in that the users might not charge the battery long enough. An eight-hour charge during the night when the chair is free is not enough. Lead acid must periodically be charged 14–16 hours to attain full saturation. This may be the reason why wheelchair batteries last only two years, whereas golf car batteries deliver twice the service life. Longer leisure time allows golf car batteries to get the fully saturated charge.

Solar cells and wind turbines do not always provide sufficient charge, and lead acid banks succumb to sulfation. This happens in remote parts of the world where villagers draw generous amounts of electricity with insufficient renewable resources to charge the batteries. The result is a short battery life. Only a periodic fully saturated charge could solve the problem, but without an electrical grid at their disposal, this is almost impossible. An alternative is using lithium-ion, a battery that is forgiving to a partial charge, but this would cost about six-times as much as lead acid.

What is sulfation? During use, small sulfate crystals form, but these are normal and are not harmful. During prolonged charge deprivation, however, the amorphous lead sulfate converts to a stable crystalline that deposits on the negative plates. This leads to the development of large crystals, which reduce the battery’s active material that is responsible for high capacity and low resistance. Sulfation also lowers charge acceptance. Sulfation charging will take longer because of elevated internal resistance.

OK, so back to the title of this thread-

Solar power cannot guarantee to fully charge your batteries, especially in winter. Likewise, neither can a conventional split charge system.

The only way to prevent gradual sulphation of your batteries is completing a full charge cycle by means of a B2B charger or the MH's built in charger.

Any questions?

 

[hilldweller]

You seem to be missing the point. Those who can't hook up need solar to survive. In reality a shortened battery life is probably cheaper than paying hook up regularly.

 

[jonandshell]

You seem to be missing the point. Those who can't hook up need solar to survive. In reality a shortened battery life is probably cheaper than paying hook up regularly.

I am not missing the point as regards the effect of solar opportune charging on your batteries.
However, putting the health of your batteries to one side, solar is a good thing! It provides a hassle free energy source and it can offer complete charging if it is sunny, your useage of power is low, or your van is in storage.
We never go anywhere sunny, use little power or store our van!

It did say this would be controversial!

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[RS_rob]

Sounds like Memory Effect to me

 

[jonandshell]

Sounds like Memory Effect to me

In layman's terms, yes!

 

[RS_rob]

yay I finally leanrt something about batteries & my mate & the tinternet was right
My RC batteries suffer that cos i never discharge them properly

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[Mike B]

So how about using solar for the meet/rally and then putting your batteries on full charge for 24hrs on your return home?

 

[DP+JAY]

All I know is we have 3 year old cheapo leisure batteries charged by cheapo solar panels with a cheapo regulator for 3 years and it all still works. Except in the deapths of winter(when we use hook up if away for longer than a few days)the batteries are showing fully charged long before the daylight goes.

 

[jonandshell]

Of course, incomplete charging by ANY means damages batteries.
I was just picking on solar as the most likely culprit!!!!!!!

However, in answer to the above question, despite our sixty megawatt atomic Sterling Alternator to Battery charger, we frequently arrive home from short trips with partially recharged batteries.

Plugging into EHU and letting the built in mains charger finish the charge cycle is the only answer.

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[DuxDeluxe]

I'd better chuck the solar panels away then...... for fear of terminally damaging my £80 leisure batteries.

Ducks know bugger all about electrickery but It really needs to be put into context and thousands of solar panel users appear to have no issues.

Thanks for the information but we will manage the risk, thanks

 

[cliffanger]

Cliff had a lecturer at college years ago who used to be an officer who worked on submarines and whose duties were maintenance of battery banks which on a diesel submarine was the most important job. He told us for maximum life on a lead acid battery they need to be periodically discharged fairly rapidly them brought back up to a full charge but not too quickly. His theory being that this practice descaled the plates. He said in the real world where we all need to use our batteries all the time it's a very difficult thing to so as a rule.

 

[Techno]

I have an inverter with built in 3 stage charger now i.e. a UPS
The last three times I hooked up I turned the charger on only to find that it reports my batteries as full.
So this concludes that my 300watt solar is keeping my batteries tip top so I expect them to easily last beyond their warranty before giving them away after 4 yrs and renewing.

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[jonandshell]

I have an inverter with built in 3 stage charger now i.e. a UPS
The last three times I hooked up I turned the charger on only to find that it reports my batteries as full.
So this concludes that my 300watt solar is keeping my batteries tip top so I expect them to easily last beyond their warranty before giving them away after 4 yrs and renewing.

A good example of your solar charging keeping up with, or exceeding your discharge rates.

Many folks fit only a 100 watt panel and the resulting charge, discharge, partial charge, discharge, partial charge cycle is what will cause sulphation issues.

 

[Allanm]

I didn't think that lead acid batteries suffered from memory effect. I used to work for BT many years ago, all exchanges were run by banks of lead acid batteries permanently connected to the equipment at one end and a charger. Very rarely were the batteries put under extended load ( only during a power cut, but most exchanges had generators that would cut in after a few minutes.
These batteries lasted for years with just regular topping up and SG checks. In fact when one of the exchanges closed down, I bought the batteries and used them as a huge UPS system. They worked perfectly for another few years. If they had been subject to the memory effect I would have thought they would have had a very short life.
Allan

 

[vwalan]

i find my batteries get a better charge in winter .possibly than they do in summer . i only ever use solar to charge them . apart from when driving with the trailer hooked to the truck.
isnt solar better in winter?
better ask mo. or snowy .
i,m sure it is . hee hee .

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[jonandshell]

I didn't think that lead acid batteries suffered from memory effect. I used to work for BT many years ago, all exchanges were run by banks of lead acid batteries permanently connected to the equipment at one end and a charger. Very rarely were the batteries put under extended load ( only during a power cut, but most exchanges had generators that would cut in after a few minutes.
These batteries lasted for years with just regular topping up and SG checks. In fact when one of the exchanges closed down, I bought the batteries and used them as a huge UPS system. They worked perfectly for another few years. If they had been subject to the memory effect I would have thought they would have had a very short life.
Allan

The scenario you had Alan, was that the batteries were partially discharged then recharged fully.
It is not the shallow depth of discharge that causes lead acid battery sulphation but the failure to completely recharge.
You are right in saying that you can discharge a lead acid battery any amount (but not beyond 100%) and no 'memory effect' or sulphation takes place.
Its the full recharge that is critical.

 

[jonandshell]

Interestingly, for battery spotters that is, the chances are that those BT batteries most likely failed not from sulphation, but stratification.
The lack of regular movement of the batteries would have resulted in lack of electrolyte mixing.
The acid sinks to the bottom where the concentration increases. The acid then erodes the seperator plates and short circuits in the cells occur. The battery then will not charge.

This can also occur in batteries which are not topped up with water when required. The electrolyte becomes more concentrated and the separator plates again are eroded by the acid.

 

[RS_rob]

A diagram might help right now

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[vwalan]

how about this as a diagram. first one nice blue sky solar working fine .
second one grey cloudy sky solar panels not working too good .
better not use too much leccy that day.
hee hee .

 

[RS_rob]

lol ffsk should have seen that coming pmsl

I meant of the battery in question for those following but not commenting..........

 

[scotjimland]

No questions from me.. an excellent post and glad you accepted the challenge..

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[cliffanger]

Jeff Lynne's ELO on telly so all thoughts of solar and batteries have melted into obscurity!

 

[chaser]

Just got my tractor battery off today to charge it up , alternater doesn't work, and noticed the guarantee thingy on it was 01 to 05 so it's at least 10 years old and when it's charged up tonight with an aldi charger it will start tractor for a couple of weeks before it goes flat again, how does that fit in with this charging thread

 

[funflair]

Is it true that Gel cell batteries are not as prone to sulfation as wet lead acid.

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[vwalan]

glad you enjoyed it i,m still laughing here.
winter down south is definately how to keep batteries full.
i,ll go now gotta keep packing the truck . soon be summer .

 

[Snowbird]

There is more misunderstanding regarding batteries than anything else to do with motorhomes. When I ran RVs I fitted ex UPS Hawker batteries and had 300 watts of solar panels. In all the years I ran those RVs I never once plugged them into mains electric, even when on site I chose not to have hookup as I did not need it. Admittedly all my time was spent in the sun either in North Norway in summer or Morocco or Spain in the winter. When I sold the RV those ex UPS batteries were still working fine. I now have 320 amps of battery bank charged by 4 X solar panels that I presume are around 250 or 300 watts and although I have hookup the onboard battery computer is telling me that the battery charger is doing nothing during daylight hours. I cannot switch off the battery charger, but am thinking of an inline switch as we are now on metered electric. This would allow the batteries to work. The engine charging system is by 2 alternators, one 24 volt for the engine, and one dedicated 12 volt for the house batteries. If you have a good solar system and large battery bank to store the produced power there is no need for expensive traction batteries as ordinary cheap leisure batteries will work fine. Its not everyone that has roof space for solar panels, but if you have, they are the best money you can spend on a motorhome as they have never been cheaper than they are now.

 

[vwalan]

i use hella wet truck batteries at the moment .
had varta batteries they lasted 8 years .
again just wet truck batteries .

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[voyagerstan]

got 4 trogen 120 batery bank 500watt solar . i.ve had the bateries on since i converted the bus 6 years ago never had ehu and never run out of power . it works for me so don't give a s!!t about sulferization or wotever it is .
ferry on tues hooray . STAN

 

[Tootles]

So what we saying here, that having a solar panel(s) will goose your battery(s)?
Well, for me, they keep the things charged up so that you can loaf around in a field for a week or so, without worrying if the loo isn't going to flush, and anyway, traction batteries are cheap enough...

 

[jonandshell]

Just got my tractor battery off today to charge it up , alternater doesn't work, and noticed the guarantee thingy on it was 01 to 05 so it's at least 10 years old and when it's charged up tonight with an aldi charger it will start tractor for a couple of weeks before it goes flat again, how does that fit in with this charging thread

It sounds like your battery has a cushy life!
A steady discharge followed by a complete recharge!

You smoothie, I bet you say that to all the batteries!

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