More power needed !

carico694

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Hi all
Had a great weekend wilding down at Dartmouth , got there friday tea time went for a bite to eat came back about ten watched telly for an hour , got cold put on blown air went to sleep . Awake, out all day , back at 6ish bit more telly, then darkness bloody battery went! this is only the fourth time out in our new van it has an 85amp hr which was full when i left home, my old van would go three days. I never had blown air before does it use a load of power ? I have been to my local battery dealer who tells me that the best thing is 2x 110amp hr but that means giving up room in my garage to house them, and not cheap how long does anyone else last I wonder, and has anyone else tried 2x 110's
cheers.
 
1x85AH is not going to last very long. Look at LED lights and as suggested 2x110AH or more.
 
Thanks for that
have you had any problems with alternator charging big batterys
 
carico694 said:
Thanks for that
have you had any problems with alternator charging big batterys
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I'm no expert but of course it will take longer. The self-build club will no doubt be able to help you work out exactly what you need. I'm a bit simpler than that and just would get bigger.
 
Hi Carico694,
I am using 2x85amp/h batteries without problems, but these are being trickle charged daily by a 55watt solar panel with a overcharge switch in the control panel. We can be out for a couple of months at a time.
1x85amp/h battery isn't enough for what you want to do, to save on cost join up another similar 85amp/h battery in series.

Happy Camping:)
 
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I am no expert either but I am pretty certain connecting two 12 volt batteries in "series" isn't what you need... "parallel" is what is meant otherwise you end up with 24 volts... in this case not good.

Connecting in series means connecting the positive of one battery to the negative of the other. This doubles the voltage (pressure).

Connecting in parallel means connecting the positive of one to the positive of the other and connecting the negative of one to the negative of the other. This double the capacity (storage) but keeps the volts the same...

Here endeth the preaching... :)
 
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A solar panel will certainly get you out off the danger zone. Altough you will never have 100% input in our regions it will certainly keep your battery on level. It is a good investation.
When you mount 2 batteries in parallel charged by the same means; they should be of the same model and have a relay, switch or diode between them. Otherwise the weaker battery will drain the stronger one.
Most economical solution could be: have one battery charged the old way with the alternator; and the other by the solar. When the first is going weak switch over to the second one (double way switch); then you don't have to bother about similarity.
Also check out what devices are consuming most. Everything giving warmth is a high consumer (also pumps and fans) Have LED's instead of ordinary bulbs and halogens.
 
jjwagon said:
I am no expert either but I am pretty certain connecting two 12 volt batteries in "series" isn't what you need... "parallel" is what is meant otherwise you end up with 24 volts... in this case not good.

Connecting in series means connecting the positive of one battery to the negative of the other. This doubles the voltage (pressure).

Connecting in parallel means connecting the positive of one to the positive of the other and connecting the negative of one to the negative of the other. This double the capacity (storage) but keeps the volts the same...

Here endeth the preaching... :)
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Quite right jjwagon, got my numpty head on today, thanks.

Happy Camping:)
 
Hi carico 694

I have 3 x 125 amp hr Varta starter batteries connected in parallel. This is a useful site tell help with electrical stuff.

Cheers Big Trev.
 
You didn't say what you use to charge the battery up before you leave. Some EHU units are not really chargers so don't do a good job of getting the battery close to 100% to start with. Charging via the vehicle alternator is not a lot better and with either method, assuming only a couple of hours on charge, it might result in the battery being more like 85% charged than 95%. Add to that your use of the heater blower - maybe a couple of amps per hour for say 12 hours - plus a bit more telly than usual and your battery monitor (if it has any consideration for your nice expensive battery) might well be signalling "enough".

[an 80 Ah battery charged to 80% has 64Ah stored. A battery shouldn't be taken much below 50% (depends of course) so that only gives you 64 - 80/2 = 24Ah before the battery monitor signals "empty". Work out your telly use and a rough average for the blower and a few lights and 24Ah might be all gone in a normal cold day]

Adding an identical battery directly in parallel (with appropriate protection against fault currents)will help a lot, ensuring your mains charger iS a decent three-stage one will also make a huge difference and of course if you run your absorbtion fridge on 12V on the way to the camp site, making sure it only runs when the alternator is charging will also help a lot.

Don't rush in an plaster your roof with solar panels either unless you carefully analyse your anticipated usage patterns. Even 1000W of panels are going to do ####-all if the sun is behind storm clouds in the winter - and in the summer, you shouldn't need the heater so your existing set up may be quite good enough for what you need.
 
Thanks for that Tony
I am charging it at home just by pluging in my hook up for a few hours before heading off, I guess thats what you mean by EHU,the trouble is at the moment I am only getting away weekends and not traveling far.
cheers paul
 
carico694 said:
Thanks for that Tony
I am charging it at home just by pluging in my hook up for a few hours before heading off, I guess thats what you mean by EHU,the trouble is at the moment I am only getting away weekends and not traveling far.
cheers paul
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I asked about how you were charging because a lot of MHs have a 13.7V power supply rather than a full three-stage charger. These are fine and will get the battery to a fairly good state of charge given enough time, but my reading indicates that the chemical process of charging just can't reach completion unless it is taken up to the point where gassing begins. 13.7V is below that point. The same limitation applies to vehicle alternator outputs - it is carefully designed to NOT reach the gassing point so that on extended drives the battery is not overcharged.
The overall result is a tendency to end up with chronically undercharged batteries that don't deliver either the performance or the life they could.

Of course these are generalisations and for every story of short lifetime and poor performance there will be stories of long life and fantastic performance - all of which must remain anecdotal because no two owners use or abuse their batteries in exactly the same way. Having AGM or Gel batteries also can make a big difference to results obtained under seemingly similar usage patterns.

You have an 85 amp-hour battery. Others have maybe a 110Ah battery and I and many others have two 100AH in parallel. [on my rig back home I have 640W of panels and 530Ah of battery at 24V and STILL very occasionally run short of power, so nothing is 100% reliable] If yours is not being 100% charged and Graths for instance is a 110Ah being fully charged, then the difference could easily account for the widely differing experiences. Even a small amount of solar or a short run each day can add up to another 2:1 variation in endurance.
 
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