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Battery Performance


Ian and Jill Brown

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We have just arrived back in Perth after picking up our 18'TE in mid December.

Our van came with provision for a 30l Engel and with 3 x 120 amp Solar panels and corresponding batteries.

When the Engel was on (freezing), we were getting approx. 2 days before our available voltage dropped to very low 12's and then struggled to re-charge even though the temperature was in the 30-35 degrees (and over 40 on some days).

Could anyone with the same option let us know their experiences so we can determine if we have a problem or not.

Other than some minor issues (too hot for a Honda genny to run the a/c - we now have a Yamaha that performed faultlessly) the van performed really well.

Ian & Jill Brown

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Hi Ian & Jill,

We camped one Xmas near Brisbane when the temps were about 38- 40 degrees and ran an Engel as a drinks fridge (not as a freezer). We have a 230 lit Vitro frigo and were using power in the evenings to watch a DVD so nothing too excessive. We have 4 panels and 4 batteries and we experienced the batteries running down and funny read-outs on the regulator/thingo (senior's moment :confused: ).

What we think occurred, after talking to Kimbo & Darryl, was the solar panels actually drop in efficiency in high temperatures so the batteries were not receiving a good charge. In the end we had to run the genny to charge the batteries.

Kimbo said he experienced a similar episode when he did his trip to the Gulf so maybe he will add more.

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Yes at high temperatures the output of the panels drop off. Also remember that the panel temperature is significantly higher than ambient temperature (Very dark in colour and in full sunlight).

This can be seen in this file: (BP 80w multicrystalline panel datasheet)

http://www.bp.com/liveassets/bp_internet/s...solar_BP380.pdf

Specifically the BP 380 I-V Curves figure.

The output power is a multiplication of the V and I numbers in the figure.

The panels peak power is found at the curve knee, its the regulators job to keep the panel operating in this knee region (as well as to stop overcharging the batteries).

One common method to reduce panel temperature is to ensure that there is a large air gap between the panel and the roof, as this will allow air flow to by convection cool the panels.

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Hi

I see it as a combination of a couple of things.

1. The Engel run as a Freezer is very power hungry as the compressor does not cycle but runs continously. From memory i think they draw 7.0 amps.

2. As others have mentioned when in high temperatures the panels efficiency seems to drop off.

One of the best solutions is to run a 2nd fridge as a fridge and not a freezer because remember you are running two fridges and in higher ambients the Vitro will use more power due to more frequent compressor run times.

I know Kimbo runs a engel as a drinks fridge off the aux batt in his Cruiser but connects the aux batt to van when stationary so the Solar charges that batt as well.

I have run a Waeco off my Cruiser aux batt as a freezer and connected it to the van to charge the Cruiser batt but it is difficult to keep all the batts fully charged (3 batts & 3 panels) even without high ambient temps due to the power hungry Freezer.

Cheers

Darryl

Ps Kimbo said "What he said" "Oh what a feeling 200" :laugh:

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Hi Ian & Jill,

We had a problem were everything would just shut down then kick back in. This would happen all the time whether you occupied the van or not. The radio would always show it was on stand by even if it had been turned originally. The regulator would show 13.9 volts plus, then shut down. We would have to run the generator to power up the battery's, but the battery's were fine, we think it was a faulty regulator.

I spoke to Ashley at Kedron and I installed a new regulator and there hasn't been any drop outs and the battery's are reading at 100%. everything seems to be oK. We will have to wait till our next adventure to test it .

Regards,

Kingy :thumbsup:

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