Deep cycling

yeoeleven · Guru

Deep cycling

DeBe · Guru

With that voltage range your batterys are not being fully charged. You should have atleast 14V when the batterys are at there end of there end of charge cycle. After 100ks of charging the voltage at the battery should be higher than 12v.

oldtrack123 · Guru

Hi John

If that 11.5v is with is with the fridge not running ,your batteries are going to have a seriously SHORT life

If it is with the fridge running ,then you are taking the batteries far below what is safe for a long life

The voltage with no load should not be below about12v @ the batteries @anytime

The batteries need to be recharged to at least 14v on a regular basis [preferably at least every 3or4days] to prevent sulphation will will quickly shorten their effective life

!2v at the end of the drive indicates that the batteries are not recieving sufficient charge , or are already in trouble, one expect around 12.5<12.7v

Peter

-- Edited by oldtrack123 on Sunday 25th of September 2011 10:12:54 PM

PeterD · Guru

yeoeleven wrote:
I have a Hi Ace campervan with a seperate battery for running the car. I don't want to get into how much power my fridge uses etc. and how much my solar power unit contributes,

Hi John - I think we do need to broach that subject, however we can be very general ablut these things.

Are you using a three way fridge or is it a compressor fridge?
If it is a three way one, are you running it on 12 V witout the motor running?
If it is a three way one, can you run it on gas?

A three way fridge will draw around 12 A continuously. Your battery will not be large enough to run a 3 way fridge on battery. That will be the cause of your problem.

I had a neighbour that had a similar problem. He had no gas installation in his van. The stove was a portable high pressure unit with a small gas cylinder. The idiot of a builder who did the conversion for him told him he did not need gas for bush camping, the fridge would run off the battery. He destroyed several batteries before I discovered what was happening.

I got him to get a cylinder installed to feed the fridge gas input. Problem solved. A few years later when he traded it the battery I installed for him was still in good condition.

The battery box he had installed was under one of the seats. It had a lid with a gas sealing gasket. The box was vented through the floor.

I suggest that with the treatment your battery has sufferen, it may have expired (assuming of course I have correctly picked that you have been running a 3 way fridge on a battery.)

bill12 · Guru

G,day. Peter, I have a 55 ltr comp fridge and 2 deep cycle batteries, plus 160w solar, and my voltage is 12.3 after the night and 12.6 during the day on solar. When starting the engine it goes up to over 13v. Is this good?It seem so when looking at the other posts. Thanks, Bill

jimricho · Guru

Unfortunately there is insufficient information to provide a "long distance" diagnosis of your situation (as implied in the previous responses).

a few questions..

1. Is the fridge a 3way (gas, 12v, 240v) or a compressor type ie. does not run on gas and has a motor?

2. Are the batteries connected in series or parallel? I know you said series but I have no idea of the extent of your technical knowledge so please excuse me for asking this as many folks do get series and parallel mixed up. If the batteries are each 12 volts it will mean they are in fact connected in parallel, if they are each 6 volt batteries it means they are connected in series to obtain a total of 12 volts. (a much better option when using two batteries to obtain a desired capacity)

3. How big are the batteries, are they the physical size of the usual 100ah (12v) battery, ie about 300mm long? (12 inches in mediaeval measurements)

4. What is the size (watts) of your solar panel(s)?

While you imply you don't want to get too technical and theoretical, without providing this info it not possible to be of much help.

It is quite possible that your system is ok and that a 100km run is insufficient to fully recharge the battery bank, also perhaps your solar panel is not large enough. A start point would be to install a 240v "smart" charger and get the batteries up to their full charge. A smart charger will tell you when this is achieved.

Note also the comments above about the effect on the life of the batteries of not fully recharging them, also that the batteries may already be significantly reduced in their capacity as a result of being consistently under-charged.

yeoeleven · Guru

OK I thought as much, I need to get more information for the answers.

I have a 105AH battery bought in May this year and a 115AH bought this month. They are connected negative to negative and positive to positive.

The fridge is a small Evercool model which is 12 & 240 volts, no gas and no freezer. I have been running the fridge all night since I installled the additional battery. The solar panel was supplied as 120 watt folding type.

The only other usage is the small pump supplying water to the sink from the undervan tank and a 20 led light.

John

-- Edited by yeoeleven on Monday 26th of September 2011 08:28:28 AM

Ron and Shirley · Senior Member

Your Solar Panel and short trips are not charging your second battery enough and as a result you could have killed off your battery, or at the very least shortened its life. This time of year down south is not the best for Solar.

You need to get your second battery up to around 13+Volts. When you are running your generator, or on 240v power, you should have a smart charger, say a Ctek XS 7000, connected to your second battery and run it for a few hours every few days.

Another approach could be to install a DC-DC smart charger that will charge your second battery better whilst you are driving, though as you have and use a generator I would be inclined to go with the 240v smart charger.

Turning your fridge off and leaving it closed in the cool of the night will conserve some power.

jimricho · Guru

The batteries are in fact connected in parallel. Series connection involves connecting two 6v batteries, the positive of one battery to negative of the other battery, note this is the only link between the batteries when series connection is used. The unused positive and negative terminals are the connection points for the wires going to the system (in series connection).

Don't worry about checking the physical size of the batteries as you have given the battery size. If connecting batteries in parallel they should be identical in regard to brand, type, age, and capacity. As the batteries are near new, and not a whole lot different you'll probably "get away" with the batteries not being identical although this is not ideal. When replacing the batteries next time round make sure that both batteries are replaced at the same time and that they are identical, also be aware that even so, if they are "wet" batteries (the ones with caps to top up the electrolyte) parallel connection will reduce their lifespan.

Another precaution (and this comes from a professional battery expert (not me, but I endorse this)) is to use heavy gauge battery straps to interconnect the batteries and to connect the positive wire going to the system to the positive terminal of one battery and the negative wire to the negative terminal of the other battery. This is to ensure that the load is shared equally between the batteries.

I don't have hands-on experience with solar but I would think that 120 watts would be adequate (solar experts may suggest otherwise so go with them if they do) and that the solution at this stage (regardless of the size of the panels) is install the smart (3 stage) charger and top up from the mains when available and/or (if necessary) the generator, via the charger and not the 12v output from the generator (if it has one)

It is important to get the batteries back to full charge whenever you can to get the full life out of the batteries. Given the cost of replacing batteries, a good quality multi-stage "smart" charger (15-25 amps) is a good investment.

(PS: I was typing my post when Ron and Shirley posted theirs hence some repetition, also note their comments re the DC - DC charger)

-- Edited by jimricho on Monday 26th of September 2011 09:16:29 AM

Loki · Senior Member

Hi Yeoeleven,

I have a Hiace van that I'm upgrading the house power availability from the small normal car battery that came with it to something that I can free camp for 5-7 days. I've had electronics training many years ago in weapons systems radar, computers & the associated control circuits but got quite a shock when looking into 12V DC! It is quite a specific area esp when also considering solar.

My needs aren't great, essentially a 12V only fridge drawing 4A when running, a laptop and a small portable DVD player. Occasionally I run the electric water pump and charge my cell phone. My lighting when I'm camped is all LED.

To date I have:-

>Bought a 105AH deep cycle AGM battery, which I am currently running independently: I have a 380W full sine wave inverter and a cigarette lighter plug attached to it for running my laptop and charging my cell phone (which only has a 240V adapter).

>Bought a 16A Smart Charger with a Rejuvenation feature as well as the three stage 'normal' charging.

>Bought a 100W portable solar panel.

>Attached Anderson plugs to both house batteries (they are still independent of each other) to attach the charger/solar panel.

>I have just purchased a second identical 105AH deep cycle battery: As the other one is still fairly new they should still match up reasonably well. I will connect them in parallel and replace my existing house battery.

>An MPPT regulator for my solar panel is on it's way: The MPPT regulator is more efficient than the one supplied with my solar panel but is also an extra expense.

At this stage, the two batteries need to be connected in parallel, replace the existing house battery and then test it to see how long I can feasibly free camp for. It appears that after 4-5 days I may need to turn the fridge off and live off packaged food, but that's OK because I'll need a good shower soon anyway! If this doesn't suit my needs then I'll look at a solar panel permanently attached to the roof.

My strategy has been to make a change, then take a run out testing, then think about the next step and repeat the process. I have to be home again in Nov so will wait until then, when I have access to my workshop again, to install the new MPPT regulator and review the wiring: With high current 12V wiring you need to ensure the wiring is of sufficient size to keep losses to a minimum. I've been using the book "Motorhome Electrics - and Caravans Too" as a guide but if you know the specific data you need (Eg what wire size to carry 10A over five metres?) you should be able to find the answer online quite easily.

A bit longwinded, hopefully useful to you. As for your original question, I agree with Oldtrack123, that

"... The voltage with no load should not be below about 12v @ the batteries @anytime.

The batteries need to be recharged to at least 14v on a regular basis..."

Happy travels!

Cheers,

Anton

blaze · Guru

What I cant work out when people say that all batteries must be idendical in size and age to be successful in a multi batery sysyems is the minute you hook the vehicle in, that equation goes out the window. I have only one battery in my van ATM with 2 in my vehicle, all three batterys are of different types and sizes. I know of no van that has a start battery in their van or no vehicle with a decicated deep cycle battery as a start battery.
cheers
blaze

oldtrack123 · Guru

Hi Blaze

I can undrestand your confusion

IDEALY the batteries should be the same type, age, size , brand etc & this is often pushed by battery sellers [more sales]

In actual practise different sizes ,brands ,capacity & age are regularly mixed with no problems The problem with using mixed age batteries is that the older one may partially short internally & discharge the newer one, if this is not detected & goes opn for a period it MAY damage the newer battery

However this problem can occur even with new batteries when in parallell

The way to minimise this problem is if you appear to have lost capacity have the batteries individually checked

Different capacities is of NO significance but is best kept reasonably close

ie not something like an 7amphr with an 80amphr without fusing betwen the two

The reason being that if a short developed in the extra small battery ,the current available from the larger could cause an explosion or fire

Peter

jimricho · Guru

oldtrack123 wrote:
Hi Blaze
I can undrestand your confusion
IDEALY the batteries should be the same type, age, size , brand etc & this is often pushed by battery sellers [more sales]
In actual practise different sizes ,brands ,capacity & age are regularly mixed with no problems The problem with using mixed age batteries is that the older one may partially short internally & discharge the newer one, if this is not detected & goes opn for a period it MAY damage the newer battery
However this problem can occur even with new batteries when in parallell
The way to minimise this problem is if you appear to have lost capacity have the batteries individually checked
Different capacities is of NO significance but is best kept reasonably close
ie not something like an 7amphr with an 80amphr without fusing betwen the two
The reason being that if a short developed in the extra small battery ,the current available from the larger could cause an explosion or fire
Peter

I've personally experienced the battery life shortening effects of parallel operation of wet cell batteries. This effect was not just a one-off, it continued to occur until I changed over to series connected 6v batteries. End of story.

(edit to correct typo)

-- Edited by jimricho on Monday 26th of September 2011 07:04:12 PM

jimricho · Guru

blaze wrote:
What I cant work out when people say that all batteries must be idendical in size and age to be successful in a multi batery sysyems is the minute you hook the vehicle in, that equation goes out the window. I have only one battery in my van ATM with 2 in my vehicle, all three batterys are of different types and sizes. I know of no van that has a start battery in their van or no vehicle with a decicated deep cycle battery as a start battery.
cheers
blaze

The start battery and aux batteries are isolated from each other by the dual battery isolator. The only time they are interconnected is when being charged from the alternator when current then flows from the alternator to each battery and not from one battery to the other. Check it with an amp meter if you doubt this.

(ok village pedants, I know that some surface charge from the main battery may briefly flow from the main to the aux immediately after switching the engine off if the voltage is still sufficient to hold the isolator closed, I've observed this effect for myself)

-- Edited by jimricho on Monday 26th of September 2011 07:14:49 PM

oldtrack123 · Guru

Hi Jim

Perhaps you can explain why you had trouble ,the current flow path that caused the problem

When mixing battereies in parallel:-

battery sizes is not a problem

Mixing different ages in parallel is not a problem unless one battery has or develops a high leakage current due to a partial internal short circuit

Mixing different types of lead acid batteries is not a problem as long as the charging requirements / parameters are similar

They will discharge @ the same %rate

One cannot discharge more or before the other

Their voltage must go down equally[be the same]

They will charge @ the same % rate

Mixing sizes /capacity is no problem for the same reasonsyou will have the combined true capacities of each battery

One battery capacity may be less than the other due to age difference but you get the combination of the ACTUAL capacities

JUST THE SAME as paralelling different sizes

Mixing different sizes in a series a arrangement is TABOO for very obvious reasons

This has nothing to do with isolation from starter battery

The only reason for isolating the starter battery is so it will not be drawn from & pulled down with the load on the house batteries& THAT level may be to low to start the engine

Very simple electrics realy

Peter

-- Edited by oldtrack123 on Monday 26th of September 2011 07:49:44 PM

yeoeleven · Guru

Thank you for the helpful advice. It seems to me that I need to buy a smart charger, either 240volts via the generator or battery to battery. From a convenience point of view the battery to battery option is preferrable especially since I will be traveling at least 50kms per day and mostly more.

Which brand/model would be the most suitable. My usual method of purchase has been Ebay but that now is hard from the delivery aspect so I will have to wait until I get to a major town having just left Port Lincoln heading towards Ceduna.

John

oldtrack123 · Guru

Hi Yeo

Just going back a bit

Your fridge is a compresor fridge it's current draw per 24hr can be between 30 <100Ahrs

This depend on your ,temp setting, ambient temp ,door opening time, Warm loading

Freezing uses up to 100Ahrs per 24hrs What setting are you runing the fridge on,TEMPERATURE???

your current useful batterry capacity without doing any damage is /was !32 Ahrs but only if you fully replace that each day

if you do not put in a little more than you take out the batteries will eventually be FLAT

An 1hrs drive is very unlikely to put in more than 30Ahrs into the battery

your solar will put in about 7amps per hour that it is in bright sun

A battery to battery charger will not help unless you drive for much longer times

But the first thing I would do is get the batteries checked, one may already be damaged [the original] due to excessive discharging & have little capacity left or an internal short pulling the other one down.

Peter

PeterD · Guru

jimricho wrote:
I've personally experienced the battery life shortening effects of parallel operation of wet cell batteries. This effect was not just a one-off, it continued to occur until I changed over to series connected 6v batteries. End of story.

No I don't believe it is the end of story. Suggest you read http://www.caravanandmotorhomebooks.com/articles/interconnecting_batteries.htm

I would be more inclined to take Collyn's advice than yours.

PeterD · Guru

yeoeleven wrote:

Thank you for the helpful advice. It seems to me that I need to buy a smart charger, either 240volts via the generator or battery to battery. From a convenience point of view the battery to battery option is preferrable especially since I will be traveling at least 50kms per day and mostly more.

Which brand/model would be the most suitable. My usual method of purchase has been Ebay but that now is hard from the delivery aspect so I will have to wait until I get to a major town having just left Port Lincoln heading towards Ceduna.

John

John, I don't think that 50 km a day is sufficient to charge your batteries. Even if your alternator is putting out 14.4 V or more it will take several hours to charge your two batteries.

Have you measured the voltage the alternator puts out after half an hours driving? Most vehicle alternators have temperature compensation in them. As the alternator heats up the output voltage reduces. Get yourself a cigarette lighter plug. Run a a couple of wires from the terminals to the test probes on your meter. Tape the wire connections over to stop them from becoming disconnected as well as shorting together.

Plug the plug to a socket on the dash. Note the highest voltage achieved shortly after start up. If the voltage does not rise to 14 V quickly then the poor condition of your batteries will be preventing your alternator from reaching the maximum voltage your regulator will allow. Your batteries will be taking to much current and overloading you alternator. You will have to disconnect your house batteries to conduct this test. If you disconnect your house batteries (never disconnect your cranking battery) and your alternator voltage does not rise to 14 V or more you have a defective alternator, do something quickly about it. When you have your alternator running at over 14 V, drive for 3/4 to an hour noting the output voltage. Please report back your readings

My D40 starts at around 14.5 V (depending on the ambient temperature) and drops to around 13.8 V in 20 to 30 minutes. It then fluctuates up to 0.35 V depending on the ambient temperature an how hard I am working my motor.

I would suggest you get yourself a quality battery charger (not a K-Mart type) as soon as possible. If no one suggests a good alternative then a C-tek will do. Get one with a 15 to 25 A capacity.

-- Edited by PeterD on Tuesday 27th of September 2011 12:15:32 AM

jimricho · Guru

PeterD, I don't doubt Collyn River's professional expertise or background but I can only go with my own experience.....

This involved the starting battery on a stationary diesel engine powered generator with automatic starting (in the event of a mains outage). On cold mornings (below zero Celsius, not uncommon where it was installed) the engine would fail to start. By using two parallel truck type batteries this would overcome the starting problem but introduced a new one, that is the batteries would only last for little more than a year ("last" meaning capable of reliably starting the engine).

Replacing the batteries did not overcome the longevity problem and it was only when I was told not to parallel the batteries but to replace them with 6v (series connected) truck batteries that I solved the problem and achieved good battery life. I found out that at the time (before the advent modern AGM batteries) that the "conventional wisdom" was not to connect batteries in parallel.

I do reiterate that this involved wet (flooded electrolyte) batteries and not modern "sealed" types that weren't available at the time. It's still my belief that if opting for wet cell ("open") batteries (most likely for budgetary reasons) where a single 12v battery of adequate capacity is not available, a couple of large 6v truck (or marine) batteries is a good economic solution, including for use as caravan/RV house batteries.

I do believe that if intending to parallel connect batteries (eg AGMs etc) it would make sense to follow the suppliers advice (as outlined in my earlier post) as doing otherwise may risk compromising one's situation in the event of a warranty claim.

PS: I have used Ctek chargers (I have two) for many years and have found them to be an excellent product.

blaze · Guru

still seems to me Jim that with my system the vehicle battery charges first and then the ecccess feeds into the secondary vehicle battery and onto the van battery. This is helped along by a solar panel mounted on the roof of the van (this panel will maintain the van battery and secondary vehicle battery when the vehicle is not running but the 3 way fridge is on 12 volt and 12 volt compressor fridge is running. So to me this is a fairly normal system which charges and discharges 3 vastly different batteries and to do the correct job as individual batterys can never be the same size and type. My start battery is 5 years old, second vehicle battery is 3 years old and the van battery about 6 months old. When it is all hooked up it is parralel connected. Not saying a set of sries connected batteries is not right because it is for a lot of situations but not the be end of all systems.
cheers
blaze

oldtrack123 · Guru

Hi Jim

Your one off experience hardly proves the case& you still have not explained why this would occur

I note you did replace the batteries with truck batteries perhaps the batteries you were using simply did not have the CCA required& were damaged due to that.

If so that is nothing to do with the parallelling

It was simply WRONG battery selection

LEAD ACID batteries , flooded wet cell & Agms can & are quite safe to parallell , with one proviso, that the max charge volt be set to the lower of the makers recommendation

This is important with AGMs as excessive charging can damage them[dry them out ]whereas flooded wet cells can have distilled water added

GEL batteries are a different matter & should not be mixed with other types as their charge voltage is quite different

Peter

-- Edited by oldtrack123 on Tuesday 27th of September 2011 09:30:49 AM

yeoeleven · Guru

I am nowhere to buy a battery charger of the recommended 15 to 25 amp but will be in Ceduna soon.

So is there any significant difference to the 240 volts usage to charge the batteries, does a 25 amp draw more voltage than a 15 amp or does it do the job more quickly.

My generator is 1000KVA will it handle the larger amperage chargers and still have some left over for the laptop or TV.

I have no spare socket connector to experiment using the voltmeter as has been suggested but may be able to get one in Ceduna. The west side of the Eyre Peninsula does not have the towns to buy much at all.

John

PeterD · Guru

John, A bigger battery charger does not draw more voltage, it draws more power. Provided it does not overload the generator the voltage remains stable but the current output increases as you increase the load on it.

A 25 A battery charger will deliver around 350 W of DC power when it is charging at its maximum output. When the bulk charging phase completes and the charger goes into its absorption stage the power delivered will start to fall. Your battery charger will not be 100% efficient so allow up to 500 W from your generator. That will still allow a fair bit for your laptop and TV.

grandadbarney · Member

Hi

have you checked what amps the alternator is putting out I just replaced my 55 amp with a 120 amp to be able to recharge the extra batteries

Malcolm