[D.Salkeld_Ltd]

Hi folks,

Has any of you fellow Backpackers had problems with the battery not charging?

I have .  Twice in a month the battery was flat AFTER being charged.  Turned out it was the charger!!

I solved the problem by buying a good charger from Maplins AND a Voltmeter to test the battery.  I went on the Internet and found some usefull info about Sealed Lead Acid Batteries:

A 12v 7ah Battery should have:

13.8 volts fully charged
11.8 volts totaly flat
Below 10.8 volts it won't recharge - nackered!

Today I used about .7 volts of power.

Any eletricaly Knowledged people out there to add any further advice would be appreciated

David

[windows_chepstow]

Fellow backpacker,

My battery went 'pear-shaped' a couple of months ago, after about seven months of constant use.

In the end, after a 'safari', I sourced a new one for £5.00 from a Motor World in South Wales.  Apparrantly it's the same battery as used by those electric scooters kids play with.

I had to change the spade size (the connections), but it was simple to do; even for a cack-handed DIYer such as myself.

It's been working a treat ever since.

I've not had any problems with the small charger that came with my UK purchased backpack.

[jeff1]

Hi Dave
If any battery weather it be a car, backpack, or any other type of battery is used in what is known as a cycle mode,ie constantly charged and then used until flat, then the battery will last only 2 thirds of its expected life. as you said 13.8v is a fully charged battery,and this voltage is also correct for a car battery.

dave if you charge your battery until fully charged, and then you use your multi meter to check the voltage, this can lead to a false reading.
fully charge your battery and leave to stand for at least half an hour to settle to its correct voltage. and then take a reading, if it has dropped below 13.8 then your battery is not holding its charge.
I used a 12v battery tester, and a testers can be bought from your local motor stockist, what these testers do is put the battery under load and test it that way.
Another good way to put your battery under load is to connect a car cigarette lighter to it, this will put your battery under load, give it a few minutes to settle and then take a reading with your meter, after a few minutes your battery should have recovered enough to give a steady reading of about 13.5v-13.8v if any lower again your battery is not holding its charge.

I used to be an alarm enginner, and the 12v battery's were tested the same way as above, now a battery in cycle mode could last a year to 18 months, but a battery in stand by mode could last up to 4/5 years, you can see the difference between cycle and stand by modes.

If you bought yourself a multi meter, you can connect your meter between your pump and battery, and do a current test on it, read your instruction manual on the way to do it, this will give you a reading of what your  pump is drawing from your battery, and give you a good indication on the condition of your battery.

I could write pages on battery's but will only boar you. if you need a paticular question answered give me a shout, and i will be happy to help.

[jouk45]

tosh these terminals look realy good from that place you mentioned motorworld
http://www.motor-world.co.uk/show_prod.php?prod_id=1081

[Jeff Brimble]

 Jeff    ,a reading of what your  pump is drawing, Is this what an ammeter does ?

[jeff1]

Hi Jeff

If you use the ammeter section on your meter, it will give you a reading of how much current is being drawn from your battery, but the pump must be running to get a reading. hope this answers your question.