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Quote: Originally posted by LobeyDosser on 16/5/2008

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Your Tracker Company will phone you and let you know when your main battery is running low and needs recharging.

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Quote: Originally posted by gm4pgv on 16/5/2008

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150 Mah + 100 Mah = 250 Mah. drawn from a 110 amp fully chatrged battery with nothing else running, will in theory, run for 440 hours or 18 days.

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Hi, yes but no but!

My understanding is that a battery is not quite like a fuel tank, although rated at 110amp hours the battery is not able to deliver all the calculated capacity.

18 days could drop to 14 or so, I believe. 

This parasitic drain is goining to be a problem for vans in storage, with background devices still humming gently away.

Mr U-M

trouble is with trackers. they go in to sleep mode after 1 hr if not moved, and do not give a signal. the back up battery only lasts 10 days, soon as the van moves the tracker will start up, but if the battery is flat it cant wake up, and the tracker  company told me the other day when rung them, they cant do a test unless the the tracker comes out of sleep mode, by means of moveing the van, or turn the tracker off then back on. so. unless the van gets plugged in the car, if its being stolen to give the tracker power, it cant wake up. hense the flat battery. same with the alarm on the van. has a small 3.5v back up battery. this will go flat after 14 days or so. unless it gets power off the hook up or the car. so if your van is sited.and not there for a few weeks, your snookered.

thanks for the replies. 

When I had my caravan serviced, the chap there said people fit a small solar panel in roof light to keep battery tpped up in storage when alarm is activated. Sounds a good idea !

 Agri

You could connect up a solar panel to keep the battery charged when not in use, not sure whether the output of the panel would be enough to run your equipment but you can pick them up for about a tenner on Ebay. I've got one connected to my van when it's sat in storage so that it just keeps the battery alive and kicking!

yup i do have one on 15 watt. am going to check the battery this week. my be i got a duffer.

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Spotted some small ones in ASDA yesterday £9.99 i think.

1.5watts     "one point five"

I have 2 of these in my rooflight connected to a 110amp battery

I think they actually revived the battery a bit the small window in the battery showed clear = not fully charged, The next time i went to the van it was green showing fully charged.

Battery was disconnected from everything except the 2 panels so had nothing draining it.

Quote: Originally posted by Ulti-Mates on 17/5/2008

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My understanding is that a battery is not quite like a fuel tank, although rated at 110amp hours the battery is not able to deliver all the calculated capacity.

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The 110 a-h capacity is, I think, based upon being fully charged - which is around 2.6v/cell, i.e. 15.6V.   Caravan systems, like car systems,  charge only to 2.3v/cell, i.e. 13.8v    Also, you cannot fully discharge the battery anyway without killing it.  The tracker and alarm may well switch off fully to prevent that - worth checking.  I think it would be unsafe to assume that the useful rating of the battery is any higher than about 60 a-h.

If you have a standing load of 250 mA then 6a-h will be used each day so the battery may last no longer than 10 days.  I say 'if' because you will probably find that quite apart from the tracker and alarm, other equipment may take some current too.  Do you have an aerial amplifier for example?   My Burstner, with everything switched off (apart from stuff you cannot switch off such as the aerial amplifier),  takes about 125mA standing current.  If your is similar, you may not even get a week from a 110 a-h battery.

I'd love to be able to fit an alarm to mine for use in storage, but I cannot think of a way to do it without having to visit the storage site every week ot two to swap the battery for a second charged one.  I think I'd soon get fed up of that.

Cheers
Andrew

 

Quote: Originally posted by Bill Terry on 17/5/2008

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yup i do have one on 15 watt. am going to check the battery this week. my be i got a duffer.

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You can only get the full output of a solar panel in full sunshine, when the panel is pointing directly at the sun (both vertically and horizontally).  In a practical situation, the panel produces a LOT less than folks think.  I use a 5 watt panel purely to maintain the battery, with it completely isolated from the caravan systems, so that there is no drain on the battery - which works OK.

According to the FAQ I've just discovered here:  http://www.a-z.co.uk/solar_panels_faq_131.htm  you can calculate the useful output of a solar panel by assuming just 1 hour of full output for a winter day and 3 hours for a summer day.    Now, you have a minimum 250mA standing load (might be higher) - which, assuming a 12V battery voltage, is the equivalent of 3 watts - so you need 24 hrs x 3 = 72 watt-hours per day.  If all you get in winter is the equivalent of 15 watt for 1, i.e. 15 watt-hours then your battery will still go flat - it'll just take a bit longer.

I'd be very tempted to actually measure the standing load on the battery with a digital multi-meter, as you may have some standing load you have not allowed for.  It's also possible that standby current of the tracker and alarm are not what you've been given to understand.  250mA seems like an awful lot.

Cheers
Andrew