#11972  by raychris
 Mon Jan 11, 2010 8:05 pm
Now that my 7 year old deep cycle batteries are giving out, I want to put the maximum AHrs batteries in the available battery tray without cutting away any more bodywork to accommodate larger ones.
My dying ones are 80-83 Ahrs ones (2- 12v in parallel give me 160-166 Ahrs) and without the help of my 80 watt solar panel, (overcast days) will not let my electrics operate for more than about 1 day.

By getting 3 s c I assume that the resulting 97% charging of capacity, will allow longer stays than the that of about 75% charging capacity without 3sc.
My alternator is a "bog standard" one which can put out the usual 13.8 to 14.0v
Can this be modified to put out, I understand, 16 to 18v for 3 s c or must I somehow find this type of gruntier alternator?

On my way home from holiday, I had to get help from a well reputed Auto Technician who reckoned that DC batteries are not necessary, pointing out that they are heavier and more expensive. He said that ordinary batteries of the same size give out the same AHrs. He offered nothing about a cut-off device to stop discharge below say, about 10.8v, below which apparently this ordinary type of battery can be damaged or have its life severely shortened. He knew nothing about 3 s c.
I do actually have a device that was built in to my L300 which cuts off supply to fridge and pump to protect the fridge from 'spikey' start up low (below 10.6) voltages. That may do to potect ord battery.

I would be grateful for any comments or help please. eg, what's the simplest 3 s c that I can build in utilising as much as possible of what I have already got?
Cheers, Ray C (how do I get a cheerful face down?)
 #11974  by Nut17
 Mon Jan 11, 2010 10:13 pm
I have just fitted a "Sidewinder" 12v - 12v multi stage 30 amp charger AUS$250 to our caravan to put a decent charge into our two 100 amp AGM deep cycle batteries while driving. This installation has only just been completed so has yet to have a real test but on paper it appears to be the bees knees!

http://www.sidewinder.com.au/page168aa.html

Cheers Chris
 #11977  by Dusty
 Tue Jan 12, 2010 7:19 am
The problem for motorhomes world wide ........... how to get enough power on board.

Rule #1. Use Less!

dump the 12v fridge , use gas appliance.

Opinion; your electrician doesn't know enough to advise you.

If you can afford another s/panel then "more is better"

Deep cycle batteries are specifically designed for the work we put them to and yes you have the right ideas on cut-off device.

One the post a reply page , there is a panel you type in , to the right of that is a selection of 'smilies' , just click on the one you want. ;)
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