new DC setup with battery backup

[wisphopefull]

Apologies if this has been already covered but I didn't find the answer in search.

So I need at least 1 day of battery backup and want to keep it as simple as possible without hacking together bits and pieces or exotic parts.

I've never built a DC only setup before and I'm thinking of using the WS-8-150-DC and a 12V 225AH battery.
Load is expected to be around 40 watts, so that should run for 33 hours (battery will then be at 50%).

So the battery can be connected directly to the Netonix switch, then all I need is a DC power supply or charger is that correct?

This is not a solar site, there will be AC power available for a charger, I just need battery backup.

[sirhc]

Where as the WS-8-150-DC will operate down to 9V it is less efficient at this voltage so I would run 24V site

I would use:
(2) OPTIMA Blue Top AGM Batteries in series to provide 24V
http://www.gandermountain.com/modperl/p ... hgodF4wDDg

Minn kota Charger Dual Battery Bank
http://mk.factoryoutletstore.com/cat/20 ... hgodwfYPeQ

This Charger is a 3 stage charge so it can recover the batteries even if fully drained.

Hook the batteries in series to provide 24V which will be more efficient and each battery is charged and maintained separately

[wisphopefull]

Ok let's assume two 12V 100AH batteries to make it 24V 100AH in total which should run for 29 hours according to my calculations? (batteries drain to 50%)

I am not in the USA so I'm thinking of using these:

Battery

Charger

Datasheet says it's 6 stage charger

the Charger also has a 3 output version availble

Is that all the hardware that is necessary?

[sirhc]

pretty much that is all you need

[wisphopefull]

Thanks Chris, however I'm confused as to whether the batteries should be seperately charged and maintained by the charger.
If seperately maintained, I would need a 12V charger?

And here's the real sticker for me, how do I control the charge current going into the batteries?
According to my calcs two 100AH batteries which are not seperately charged should be charged at a maximum of 40amps (20amps per battery)
because the manufacturer states:

Code: Select all

 (The charge current should preferably not exceed 0,2C (20A for a 100Ah battery).

, so if I had a charger that provides 40amps for example and the UBNT gear uses 1.6amps, are the batteries going to be charged at 38.4amps? which would be excessive for these batteries

will the batteries soak up as much current as is available unless it is capped?