solar panel / amp 32 question

[NED 209]

hi all. im moving from Ireland to New Zealand, so ill finally get to avail of some sunlight. for this reason i just bought two 5 watt solar panels. here -

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=190243076151&ssPageName=ADME:B:EOIBSA:US:1123


ICP PowerFlex 5 Solar Panel

23V Open Circuit Voltage
Maximum output of 5 Watts
(0.3Amps at 16.5V)


im intending one of them to top up my sla battery, which is around 4Ah - i think the math is about right.

i know the amp32 uses 300mA at max level. i know the maximum voltage it can take is 14.7 volts. could one, or both, of these panels run the amp without the battery?

i gotta confess my knowledge is pretty limited

 

[theAnonymous1]

How do you plan on connecting these to your battery and the amp? If you don't already know, you will either need a DC-DC step down converter or one of the devices specifically made for solar panels.

Something like this would work well for what you have.....

http://cgi.ebay.com/Solar-Panel-Cha...ryZ41981QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

 

[NED 209]

thanks for the link, i understand ebay links best... : ]


i was hoping to get away without adding more... i think i read somewhere that that connecting the panel to the battery would lessen the voltage of the panel, once its placed under a load...

 

[Buckapound]

Last year I bought a 6.5 watt flexible panel (Brunton) for the same purpose. I can report it runs my Amp-32-powered boombox at about a third volume (decent listening level) in the midday autumn midwestern sun. Higher than that volume and the sound starts cutting out. I had disconnected the battery to see if it could run the thing. Most of the time when I'm camping I connect the panel in parallel with the battery to supply what solar power is available and reduce the drain on the battery, which seems to work. No charge controller needed for this situation.

Two five watt panels obviously ought to to better than that. Good price on those, BTW.

--Buckapound.

 

[theAnonymous1]

From what I've read about solar panels and SLA batteries, the current from the panel should be no more than 1/300th of the battery Ah rating without using a charge controller. Your two 5w panels definitely exceed that rating. I suggest using a charge controller or you risk overcharging the battery and severely shortening it's lifespan.

Also, in full sun without any voltage regulation (and no battery attached) you run the risk of the voltage going above the AMP32s max rating.

 

[NED 209]

Buckapound - kick a**. that just what i wanted to hear. yeah man, she has similar auctions for the same panels too.


TheAnonymous1, hi, i think the solar panel can be no more than 1/10th of the capacity of the battery. i think with the 5 watt panels im pushing that a tiny bit, but not much.
hopefully i wont be sitting on a beach and have a load of acid blow up in my face

 

[theAnonymous1]

TheAnonymous1, hi, i think the solar panel can be no more than 1/10th of the capacity of the battery.

For initial charging yes, 1/10th or even more is fine; it's once the battery is fully charged when the trouble begins.

 

[NED 209]

good point.


i could regard it as a charging operation and remove the panel after a set amount of time. im used to doing that, as i dont have an accurate charger


guys thanks for the discussion btw, as always its an eye opener

 

[Saturnus]

It hardly matter how high watt rating of the solar panels are as they'll provide the maximum output under optimal conditions and one for an hour around midday. Most of the time the output will range from 50% to 80% of maximum output as long as the Sun is under a 45 degree angle from zenit. Outside these conditions the output falls of dramatically.

As long as you stay within a reasonable power rating to Ah rating of the batteries, there's basically no chance of overcharging them with solar panels since it's only a fraction of the day the produce enough power for it.

Off course, if you don't drain the battery at all in between charges, there will be a slight chance of overcharging but with the use you describe, I'd wager there'd be absolute zero chance even if you doubled your current setup.