# Mixed leisure batteries as standard



## stuartc (May 10, 2008)

Hi,

My first post so hello world!

I've always thought that you should not mix different types of battery, however our motor home has come from the factory with two types of battery (60Ah and 85Ah) as a standard fitting.  It loks as though they are wired in parellel.

The motor home is about a year old, though even with a solar panel we are having poor performance from the batteries.  Everything seems fine, we changed the solar panel and the regulator, so I can only put the poor performance down to the mix of batteries.

Is it common for manufacturers to supply mixed batteries as standard and is this likely to be our problem?

Thank you!

Stuart


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## wildman (May 10, 2008)

Hi Stuart, welcome to the site, what exactly do you mean by bad performance, what is happening.


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## stuartc (May 10, 2008)

Thanks Wildman,

The batteries don't seem to hold their charge, they loose their charge quicker than the 85w solar panel can charge them.  I am of course assuming that the batteries are the same age as the motor home; 1 year.


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## wildman (May 10, 2008)

Something is being left on, disconnect the batteries from load they should stay charged. at 12 months old unless allowed to run flat at some time or dry they should hold their charge. 85amp solar panels are more than enough for the job can you read the charge voltage. Looks like you have an electrical problem, maybe a faulty regulator. (was the regulator uprated when you upgraded the panels.


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## Trevor (May 10, 2008)

stuartc said:


> Thanks Wildman,
> 
> 
> 
> ...


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## stuartc (May 10, 2008)

Thanks Wildman and Trevor, you've been a great help.

The regulator was changed also, but still have the problem.  I'm pretty sure nothing is left on, but I will check to make sure, then replace the batteries.

Thanks again!


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## Trevor (May 10, 2008)

stuartc said:


> Thanks Wildman and Trevor, you've been a great help.
> 
> The regulator was changed also, but still have the problem.  I'm pretty sure nothing is left on, but I will check to make sure, then replace the batteries.
> 
> Thanks again!


NO probs Stuart get a check done on the old ones they may have some use left in them and may be handy for something.
Good Luck.
Oh by the way if your van has stood over winter it can have a bad effect on them especialy if you dont charge them up every few weeks.


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## Nosha (May 11, 2008)

Like you, ours came with a mix of one of each in parallel. We wild for 2 -3 days inc TV & stereo etc without any problems, the fact that you seem to be having problems with BOTH can only be due to charging... or the lack of it.

We've never fully flatened the lesuire battery, but even if we did the engine battery should still start it ok (ours is 19mths old).

So they're either not being fully charged, or something is draining BOTH of them... rather unlikely, but not impossible.


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## wildman (May 11, 2008)

*oh dear*

Yesterday I added a very small solar panel to keep the main battery topped up whilst standing, (no problems prior to that) great output plugged into the cigar socket (live all the time) This morning main engine battery and fuel heater battery were both flat. Conclusion diode in charger is either non existant or faulty allowing the battery to discharge through the solar panel over night. The batteries must be linked together in some way however with one battery connected only there is no voltage read across the other two leads so somehow a relay is involved not looking forward to tracing that one out as the electrics have been much modified by various owners over the years. The leisure batteries are seperate and were not affected. You do at least have a wiring diagram to start with. With everything turned off disconnect the positive lead and using an ameter read the current between the terminal and the positive lead. (make sure the solar panel is NOT connected) that will give you an idea of the current drain that you have. If you check again when it is dark and the solar panel is connected and compare the two readings you will be able to see if the problem lies with the solar panel and or the charge regulator. The imobiliser light will be flashing so a very small current should show make a note of the current drain. Failing that get Autotrail to sort the problem it is still under warrentee is it not?


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## Tony Lee (May 13, 2008)

You said you changed the solar panel and the regulator. Given that you are an admitted newbie to solar power, was this done at random, or was there a specific reason for changing them.

Solar panels are easy to fault find (and many have a very long warranty anyway) and decent regulators are usually self-diagnosing and even batteries are really no great mystery to those with basic knowledge, so I would be inclined to find someone who knows what they are on about before spending any more money at random

Tony

If you are intent on doing it yourself you need a cheap digital multimeter that will read battery volts - accuracy to 0.1 of a volt is enough. Current range of 10 amps DC would be an advantage but not essential.

Battery voltage when charging either from solar or engine or a mains charger should be somewhere between 13.5 and 14.4 volts after a couple of hours on charge.
When all charging sources are switched off the voltage will slowly drop to about 12.6V provided there is no load on the battery. This voltage if measured several hours after all charging is stopped, indicates a reasonably fully charged battery. If it is less than than that then try disconnecting both batteries and measuring the voltage. If one is appreciably lower it may indicate a faulty cell. Repeat the experiment with just one battery connected and then the other. With both batteries disconnected and presumably fully charged, connect a load of at least 60 Watts - a headlight globe is ideal - while monitoring the battery voltage. The voltage should drop from 12.6 to say 12.4 and then slowly drop to below 12V over several hours. Any sudden large drops or fast drops will indicate either a partly charged battery or a faulty battery.

Batteries of different capacities can be connected in parallel provided they are of the same type - meaning both AGMs or both the same type (plate composition) of flooded cell battery - and the only way to ensure this is for them to be the same manufacturer and date of manufacture. Anything else may give sub-optimum results or even lead to the destruction of one or both batteries.

Assume nothing about batteries supplied in a used camper. The dealer will have a heap of batteries in the corner of the workshop and a labourer will just grab two and stick them in regardless. Unfortunately many large battery shops will do exactly the same thing.


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