# this has got me puzzled !



## bruno66 (Jun 18, 2007)

Hiya all...

Been havin a little trouble with my leisure batteries, two 95ah in parallel, was on hols a few weeks ago and batteries seemed to be charging ok but every night they would settle back down to 12.5, we weren't using any appliances at all save for the occasional water pump, got to stage that didnt even use the bloomin lights lol!. Every morning the display would show into the 13 volts. 

When we got home I checked levels , seemed ok just above the plates I think, charged both off the van for 24 hours reading 13.6 left for couple days settled back down to 12.9,hooked back up to van set off for night away on a couple hours drive so far so good. Sat out had a beer or two as you do, everything seemed ok, until the evening when reading back to 12.5 again using absolutely nothing not even the pump this time!!

Anyone got any ideas why this would be? Can't go on not using the batteries of hook up if they showing this level after maybe 3 hours not using anything...

Maybe I just gotta go to auto electrician?


----------



## rayc (Jun 3, 2008)

Where are you measuring the voltage? The inbuilt meters in CBE control panels for example can be calibrated by the user.
In any event why not do a discharge test by leaving some lamps on and see how long the batteries remain above 12v? The voltage is only an indication and a load test is the proof of the pudding.


----------



## bruno66 (Jun 18, 2007)

Hiya,

I've just been going by the display in the van I'm afraid and been scared to leave lamps on in case discharge batteries completely!!


----------



## clive1821 (Mar 27, 2010)

As Ray has already mentioned.... 12.5v is a normal standing voltage of a lead acid battery, it all depends on the pannel, which if its not an anlog meter I would not trust it, better to see whats going on directley on with the batteries, or indeed just let them work and see what happens....


----------



## DeeGee7 (Jun 22, 2009)

Have a look at this chart which shows the state of charge, hope this helps.


----------



## DeeGee7 (Jun 22, 2009)

well I don't know how that happened!


----------



## rayc (Jun 3, 2008)

bruno66 said:


> Hiya,
> 
> I've just been going by the display in the van I'm afraid and been scared to leave lamps on in case discharge batteries completely!!


Control panel meters area bit rough and ready and no indication of the capacity remaining in the battery. If I were you I would not worry too much about fractions of a volt and concentrate on what really matters which is the battery capacity remaining.

Charge the batteries, switch the charger off and wait 2 hours. Switch on a few lights and see what happens over the next 12 hours or so.


----------



## Mrplodd (Mar 4, 2008)

Wouldnt worry too much !! Dont forget also that if you switch anything on the battery voltage WILL drop on the display.

As has been said before, switch a few things on and see how you go. I have a Sky box and TV both 230v which I run off an inverter (2 x 110 AH leisure batteries) So far I have got to 5.5 hrs of telly before getting fed up and turning in. So that should give you an idea of what you can use without detriment!!


----------



## bruno66 (Jun 18, 2007)

Thanks guys

I thought I should be getting bout 12.9 and that 12.5 was about 50%.... but to be honest it all fries my brain! I just want to be able to sit in my van at night eith the option of switching the lights on for a wee while. No telly, no hairdriers inverters or anything like that ...

So it sounds like what I'm getting is perfectly normal then... thank goodness I didn't go get new batteries!

Thanks again


----------



## Patrick_Phillips (Aug 17, 2006)

Yes, I agree, it is about capacity not state of charge.
I am just changing three 110Ah Lead acid batteries which fully charge and have the little indicator showing that they are in good condition.
They aren't. They are holding about 50Ah between the three of them!
Get someone with a crank test meter (cost to buy, about £700) and get a test done.
Some big-name batteries will allow you to charge and discharge just 70 times and then they are done. Kaput. Finished. Dead and no more use!

Patrick


----------



## clive1821 (Mar 27, 2010)

bruno66 said:


> Thanks guys
> 
> I thought I should be getting bout 12.9 and that 12.5 was about 50%.... but to be honest it all fries my brain! I just want to be able to sit in my van at night eith the option of switching the lights on for a wee while. No telly, no hairdriers inverters or anything like that ...
> 
> ...


Yes no probs..... just leave some lights on for a while and see what happens, its just battery management..... if your pannel is showing 13volts in the morning i'm assuming you have a solar pannel.... age, tempreature also has a bearing of the capacity of your batteries


----------



## bruno66 (Jun 18, 2007)

Clive, yes I do have a panel but I dont think its very big, maybe 40 or 60 watt, it was on the van when I bought it. Batteries are barely a year old, hardly been used as dont have much to drain them. 

Don't know if it's connected but I did see levels go down last year to about 11.8 when travelling on a very hot day in France , for about six hours with the fridge on, I thought alternator should have kept the levels charged and stopped them from going near flat then?

Patrick who does crank tests? Auto electrician?


----------



## Patrick_Phillips (Aug 17, 2006)

bruno66 said:


> atrick who does crank tests? Auto electrician?


Yes but usually battery vendors and even people like Quikfit. Bet Clive has one 8)

Patrick


----------



## clive1821 (Mar 27, 2010)

Patrick_Phillips said:


> bruno66 said:
> 
> 
> > atrick who does crank tests? Auto electrician?
> ...


Yep I have one as well.... :roll:


----------



## bruno66 (Jun 18, 2007)

so whats involved in a crank test....? Suppose that'll mean lifting the chairs off to do that since they're under driver and passenger ... Ah well if thats what it takes...


----------



## clive1821 (Mar 27, 2010)

bruno66 said:


> so whats involved in a crank test....? Suppose that'll mean lifting the chairs off to do that since they're under driver and passenger ... Ah well if thats what it takes...


I would do what ray has already advised and put a simple load on your batteries, like a tv, 5 halagen lights for a few hours and see what happens, if the batteries go flat in 4 hours there might be some issue some where but do the simple stuff first, and do it where you can recharge the batteries if necessary after the test.... I do a simple test of using a 150watt light, with an inverter... that would take around 17 amps and gentle discharge and with your two 75AH batteries that test good batteries would last about 5.5hours, as a rule of thumb, (taking into account of the battery losses, max discharge of 80% and the air temp of the batteries)


----------



## rayc (Jun 3, 2008)

bruno66 said:


> so whats involved in a crank test....? Suppose that'll mean lifting the chairs off to do that since they're under driver and passenger ... Ah well if thats what it takes...


Why bother with a crank test on habitation batteries? Just do some load tests using the habitation electrics as loads. I don't see that it is very relavent to know that you can turn a starter motor over with them if you desired to but it is important to know how they perform on domestic loads.
Charge the batteries and let them settle for a while. 2x95ah is 190ah. Discharge them at a constant current of 9amps for 20 hours and measure the voltage every hour.


----------



## vicdicdoc (May 14, 2005)

I got one of these fitted - at a glance I can see exactly what's in the batteries & what I'm using . . exellent piece of kit
http://www.google.co.uk/products/ca...=X&ei=xuTET67NAcrX8gOIkqDRCg&ved=0CKgBEPMCMAI


----------



## bruno66 (Jun 18, 2007)

Thanks again guys ... off to switch some lights on... havent got a tv or an inverter in the van... 

Vic how easy was it to fit one of these monitors they sound like they'd be great to have


----------



## bruno66 (Jun 18, 2007)

well... after switching 4 fluorescent tubes and 2 halogen bulbs on, in under a min the van was reading 12.0 put a voltmeter on both batteries reading between 12.1 and 12.2. down to 11.9 within 3-4 mins.... can't be normal this surely?


----------



## clive1821 (Mar 27, 2010)

seems this is why you are asking the question in the first place, now you do have a multi meter, when you put the batteries on charge, have a look at the battery voltage, and it needs to rise to 14 volts + which would give you an indication of the batteries are charging this voltage would take some while to get to that level.... the idea is to see if the batteries are charging corectley or may be one of the batteries are faulty..... in which case chuck them away and replace with new batteries if necessary.... just check the charge is working first...


----------



## bruno66 (Jun 18, 2007)

Clive,

you're right it is the reason, I charged them last week with an aldi battery charger and after seperate over night charges of about 12 - 16 hours they were both reading 13.6... I thought that this was a good level but it isn't? 

Should I leave them for longer on charge?


----------



## clive1821 (Mar 27, 2010)

yes the charge is getting there, depending what current and voltage the charger will charge, I would be looking for about 14.3v ish and then come back to around 13.8volt on a lead acid battery with the charger conected.... i think you mentioned the age of the batteries but cant remember what age they are...


----------



## bruno66 (Jun 18, 2007)

only a year!!!


----------



## bruno66 (Jun 18, 2007)

but even at 12.5 would you have been expecting the levels to drop so quickly with only a few lights on?


----------



## bruno66 (Jun 18, 2007)

just gone out and checked, levels showing on both charger and multi meter 12.8 !!!???

solar can't be making that difference cos its only showing 0.20 charge

something not right surely


----------



## H1-GBV (Feb 28, 2006)

rayc said:


> Charge the batteries and let them settle for a while. 2x95ah is 190ah. Discharge them at a constant current of 9amps for 20 hours and measure the voltage every hour.


How would you arrange a constant current of 9A? As the batteries discharge, the voltage drops so any normal ohmic resistor (and a filament lamp would be even worse) would draw a reducing current.

In addition, the recommendation is "do NOT go below 50% charge", so taking 180Ah out of 190Ah batteries would solve the problem - OP would definitely need new ones. :lol:


----------



## barryd (May 9, 2008)

Very interesting all this, especially that very useful chart at the beginning. so your only supposed to let the battery go down as far as 50%. so our single 110AH is really only good for 55ah before it needs either a drive or a plug in. 

That kind of makes sense. I reckon we use roughly 10amps a day and four to five days is about as long as I go before I start looking at the needle and thinking about charging (its just a red, yellow and green zone panel). Now I have a multi metre I can check it more accurately (or have you now just given me something else to flipping worry about!)

Hope you get it sorted OP. It indeed it does need sorting.


----------



## bruno66 (Jun 18, 2007)

ok here goes see what you guys make of this... 

charged both batteries up for 24 hours each then switched 5 fluorescent tubes and (2) 10 watt halogen bulbs on, went to workand when came back 11 hours later I tested both batteries with the multi meter, showing 12.1 ish (cant quite remember the exact reading but it was between 12.1 and 12.2)

would I be right in saying this is between 40 and 45% charge left and if so do you think this is ok? I know wouldn't normally have lights on for 11 hours in one go but I would hope possibly to have more than just a few bulbs on one day so that would obviously drain more too....

the thing that I cant understand is that you hear about people going for days with no hook-up and using all manner of electrical items to boot!! It feels to me that the best I can aim for is a couple of bulbs for a couple of hours but maybe I'm reading to much into it and I've actually got more power than I think???

thoughts and experience greatly appreciated


----------



## Penquin (Oct 15, 2007)

IMO 5 fluorescent tubes and 2 x 10w halogen bulbs is quite a drain and left on for 11 hours would seem quite reasonable to me, if the reading was still 12.1 ish at the end.

Your solar panel may also be putting some in to boost it as you drain it, but as far as I would be concerned it sounds like an OK answer.

Try it for real on a trip and see how it works out - the thing that drains the heaviest current (of normal equipment) is the pump (about 8a I think) but we do not tend to run that for long periods - the longest being for the shower probably.

You are probably worrying about nothing - remember many people say they have been wild camping for days and forget to mention the solar panel, running the vehcile engine or the generator for a short while just to top up "in case". It becomes a concern if you are running a colour TV since these are voltage sensitive and will tell you if the voltage is going down by the TV going off.......  

I would not be concerned but try it and see if it works for a reasonable trip without heavy useage of electrical items (which you don't have anyway! :lol: ),

Dave


----------



## weldted (May 1, 2005)

*batteries*

A rule of thumb is if you have 100 amp battery you will get 50 amps from it any more and you will start to effect the batteries ability to recover, some constant current psu/chargers are designed to maintain 13.8 volts so as not to cause the batteries to gas, to get a leisure battery to a fully charged state needs a slightly higher voltage but this needs to be controlled so as not to loose the water in the batteries. If your batteries are fully charged or nearly so the output from the solar panels will drop as the regulator senses the state of the batteries. I would not recommend a discharge or drop tester for leisure batteries as they are designed differently from starter batteries, engine battery is meant to give a large amount of current for a short period and to be charged up again quickly, leisure batteries are designed to give a small amount of current over a longer period, rough rule of thumb is 10% out 10% in


----------

