Solar/Battery Setup for Portable Video Player

dubyasquared

Hi, very new to the solar and electrical world, have read a few posts here, but all of them seem geared toward higher end systems. I'm trying to set up a portable solar/battery system that will recharge a small portable video player while I'm on an extended road trip.

From the research I've done I've compiled a 12 volt/5 watt solar panel, a 12 volt 7ah battery, a Cobra power inverter, and a solar charge controller.

This is the problem... I have a wall charger from an old battery power pack that puts out 1.5 amps and 17 dc volts (though states 12 volts on the adapter) and today I wired it into the charge controller and setup my multimeter to check the output. (Would look like... 17 volt DC wall charger===> charge controller===> multimeter. No battery hooked up.) This is a bottom of the line $15 charge controller that states it can handle 3 amps, so I thought no problem. I hooked up the wall charger to charge the battery I just received to full capacity, with the plan to charge via the solar panel next time. Well the charge controller fried within seconds. Clearly I've committed a novice mistake, and can only assume the 17 volts was too much for the cheap charge controller. On the very sparse controller instruction, it lists 'Load Over Voltage' 'Protection 16.5 V.' 'Resume 15.0 V.'

The only other info is that the volt reading on the multimeter during the few seconds swung back and forth from 17 to 10 volts.

What exactly happened? And more importantly what do I need to get my setup running? I've tested my solar panel with a multimeter and it can put out 17-18 volts, and don't want to keep frying charge controllers to figure it out.

Thanks for any help!

Cariboocoot

Re: Solar/Battery Setup for Portable Video Player

Welcome to the forum.

Your 5 Watt panel will only put out about 0.3 Amps. As such there isn't much need for any regulation between it and the 7 Amp hour battery as it is barely a trickle charge on it. The usual system would be to just connect the panel directly to the battery, allowing it to regulate the Voltage.

It sounds like you are saying you are using both a battery charger and a charge controller. The circuitry would be somewhat redundant and probably incompatible. As a rule, charge controllers expect pure DC in and out, and the battery charger may be less than "pure" allowing some current to flow as a short across the controller causing it to fry. You really can't feed a solar charge controller from a rectified AC source, and these little chargers have rather poor rectification (often only half wave).

niel

Re: Solar/Battery Setup for Portable Video Player

it sounds like something else might have been amiss here like wiring it backwards, aka wrong polarity because the controller should have been able to withstand that voltage.

as to this,
"Load Over Voltage' 'Protection"
now isn't this the very definition of a regulator? i guess it did protect the load after all with a self destruct.

as to your battery and that pv without a regulator i would have a regulator as it is most likely an agm battery first of all and secondly the .3a is significant enough of the 20hr 7ah battery capacity rating that i would not trust it to self regulate as a battery's voltage will want to continue to rise beyond the point that the self discharge losses and other losses would present. that .3a is only .2a below what the absorb charge end amps rating is on my 104ah sunextender agm. this isn't insignificant.

PNjunction

Re: Solar/Battery Setup for Portable Video Player

dubyasquared wrote: »

What exactly happened? And more importantly what do I need to get my setup running? I've tested my solar panel with a multimeter and it can put out 17-18 volts, and don't want to keep frying charge controllers to figure it out.

Chalk this one up to experience - the way to check your charge controller is to actually use a solar panel AND a battery connected, not a power supply and no battery attached. A classic mistake is to attach just the panel to the charge controller, and without a battery try to measure the voltage output and find nothing coming out, thus assuming that the charge controller is bad. You must have a battery attached for proper operation. The other mistake is to use a power-supply as an input, and not a pure-dc panel. What happens is that the power supply - even if it meets the voltage specs - sees the battery beyond the charge controller as a dead short when you try to use it. Then the supply (if it is not specifically made for charging batteries), shorts out, blowing a fuse or crowbar circuit, which if it isn't fast enough, takes out everything downstream from it.

Your little supply is also non-regulated, that is even though it specs 12v, that is only when there is an actual load on it. Remove the load, and measure the voltage on an unregulated supply, and it is usually several volts above what the running specs are. Also, this is likely to be a poorly-rectified ac-dc supply with a large measure of ac-ripple on it, which the charge controller / and battery don't like to see.

One other mistake when trying out a charge controller is to attach the panel first, and the battery last. Unless specified differently from your manufacturer, the usual way is to attach the battery FIRST, and then the panel. If done backwards, some cheap controllers will detect a no-load condition, and not start charging - or possibly just start out in a float mode if it has it, and not do any bulk charging.

So the moral to checking your charge controller - you need to actually use a panel and a battery, typically attaching the battery first and the panel last. Substituting a power supply not specifically made for charging batteries is an ill-advised way of checking initial controller operation.

dubyasquared

Re: Solar/Battery Setup for Portable Video Player

Nice suggestions, thanks for all the tips!

niel

Re: Solar/Battery Setup for Portable Video Player

at least let us know what went amiss if you make a determination.