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confusing power readings


RodnSue

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Hi Everyone

this may be basic stuff - after uninterrupted sun on our 3 solar panels from 10 - 5pm today,our Xantrex linklite battery monitor inside the van read 81.6% & 12.6 volts.The bar status says 6 bars out of possible 10 bars this evening.

Over night the power reading dropped to approx 74% from a readout of approx 89% at end of sun. We can't remember the volts, but it didn't match the % reading if going by Russ' table. It was reading more than 12.4volts at least this morning. (we've just been using 1 - 2 lights washing up & fridge,( no showering in the van for 6wks as we haven't been able to free camp)

The panel in the front boot was blinking green today. No other colours shown. This is the 1st time we've had such lousy power reading from what seemed like plenty of sunshine.

Now this is where we are confused - according to Russ power chart in a another thread on power in April - 12.6volts should be above 90%.

We haven't been connected to power for at least a week. We had 240v power for 1 night which almost fully charged the 3 batteries.

Sunshine alone was giving us up to 97% charge. We have mostly relied on un powered sites in the parks to in the Top end.

We spent 3 days in the Wangi Safari campground Litchfield which gave us sun for most of the day.

We arrived @ Daly River yesterday & received >6hrs sun either from travelling or once camped.

There seems to be a miss match with the 2 reading & we have gone by the volt reading this evening & used minimal power over the evening as is usual for us.

Apologies if I sound crytic in my post, but can any one shed some light on what we do next.

many thanks in advance

Sue

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Hi Sue.

Batteries are tricky Devils and readings can be a bit misleading, depending on circumstances. The ideal measurement of a battery's voltage is when the battery is "at rest". That is, it hasn't just finished charging, nor is it under load. Intelligent solar regulators can improve the accuracy of the State of Charge reading if they have been correctly configured to monitor all of the current flows in the system. That is, what's going into and out of the batteries, what is coming in from any source such as solar panels, battery charger or vehicle alternator and also any current that is being fed directly from the solar regulator to the load in your van.

Most stand alone battery monitors aren't as sophisticated as those that are integrated into good solar regulators and, as such, won't be terribly accurate. The table I published should only be used as a guide (although it is pretty accurate.) Variance can occur between batteries with different chemical make-up such as pure lead acid flooded cells and Absorbed Glass Mat cells. These variances are relatively small though. A simple test of your batteries is to turn off everything in the van, including the fridge. Wait for 15 minutes (more if you can leave the fridge off for a while longer) and watch the voltage reading. Whatever the voltage reading is, just before you turn things back on, is about as accurate as you will get.

The battery readings (in percentages) that you quoted are fairly meaningless if your system is not configured EXACTLY right, and you should use the "at rest" voltage as a better guide. Including my own, I have rewired four Kedrons in order to get the system correctly configured. I seriously doubt that too many have left the factory wired the way that they should have been.

Cheers

Russ

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Thanks Bryan & Russ for your responses.

Bryan, the van is only 11 mths old. The batteries have been kept in > 75% charge apart from 1 occasion near the beginning of owning the van, due to a misunderstanding of the required charge & on that occasion it went down to somewhere between 60 & 70%.

So the life of the batteries should be good, I would have thought.

Russ, will give the test a try in the morning. We are currently attached to 240v in Katherine to give the batteries charge a helping hand.

Rod plans to synchronize the monitor when the green light in the boot is solid.

Will also see how things go over the coming weeks.

We’ve had no grief up to now, so am hoping the wiring has been done correctly ?

We used to be guided by the % reading up to this issue & had no prior issues.

I was telling a fellow vanner our situation this arvo & he suggested we should be going by the % reading rather than the volt reading.

Your thoughts on this would also be appreciated

Regards Sue

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Hi again Sue.

Don't get too concerned about things just at the moment. Battery voltages and State of Charge readings can be at odds, as I said in the previous post. I would suggest buying a cheap Voltmeter from Dick Smith (or similar) and using it to determine what the battery Voltage is "at rest", as explained previously. Try and do this early one morning, before the Sun starts to charge your batteries and after the 240 Volt charger has been off for at least an hour. Be sure to read the voltage right at the batteries, not at a 12 Volt outlet elsewhere.

Whatever Voltage you see then, when referred to the table from the other thread, will be as near as dammit what the State of Charge of your batteries is. See how that compares with the charge monitor that you are using. Remember, too, that while it is preferable to keep your batteries above a 75% State of Charge, it is not always possible to do so when the weather has been cloudy for a while. Don't get all bitter and twisted if your State of Charge gets down to, say, 50%. As long as this doesn't occur too often, it isn't going to harm your batteries too much.

Read the rules of the battery monitor that you have to see if it can be reset or calibrated at a known value such as at full-charge. This is the only way to be sure that it is telling you the truth.

Cheers

Russ

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Hi Sue.

Batteries are tricky Devils and readings can be a bit misleading, depending on circumstances. The ideal measurement of a battery's voltage is when the battery is "at rest". That is, it hasn't just finished charging, nor is it under load. Intelligent solar regulators can improve the accuracy of the State of Charge reading if they have been correctly configured to monitor all of the current flows in the system. That is, what's going into and out of the batteries, what is coming in from any source such as solar panels, battery charger or vehicle alternator and also any current that is being fed directly from the solar regulator to the load in your van.

Most stand alone battery monitors aren't as sophisticated as those that are integrated into good solar regulators and, as such, won't be terribly accurate. The table I published should only be used as a guide (although it is pretty accurate.) Variance can occur between batteries with different chemical make-up such as pure lead acid flooded cells and Absorbed Glass Mat cells. These variances are relatively small though. A simple test of your batteries is to turn off everything in the van, including the fridge. Wait for 15 minutes (more if you can leave the fridge off for a while longer) and watch the voltage reading. Whatever the voltage reading is, just before you turn things back on, is about as accurate as you will get.

The battery readings (in percentages) that you quoted are fairly meaningless if your system is not configured EXACTLY right, and you should use the "at rest" voltage as a better guide. Including my own, I have rewired four Kedrons in order to get the system correctly configured. I seriously doubt that too many have left the factory wired the way that they should have been.

Cheers

Russ

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Hi Russ

I have ordered a Top Ender and I am concerned at your mention about having to rewire some Kedrons. Why are'nt they being done properly at the factory? Have you mentioned this to Kedron so that they can maybe fix the problem at the factory?

Maybe their electrician is not doing his job properly.

Regards

Rob

Townsville

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G'day Rob,

I can't comment on recent Kedron vans. I believe that they now use different components to what they did when ours was made. Vans made previous to ours usually had either no connections on the "Load" terminal of the solar regulator, or incorrectly wired Shunts, or both. They also included an additional 12 Volt supply for use when parked at powered sites, which was completely unnecessary to install if a correctly rated battery charger was installed in the first place. It simply meant that you had two fans whirring in the boot instead of one, which if you have a front bed design, could be heard through the wall of the boot at night.

Cheers

Russ

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Hi Russ

had a good chat with Tom @ the factory this morning as the monitor reading hadn't come up to 100% after being connected to 240v for 44hrs.

The monitor is still only reading 93.8% & still flashing in the boot. It seems batteries the are full & we should sync tonight & do so every 2/12 or so. Last sync was <1 mth ago any way.

This is our 1st experience with vans so we're still learning as new things prop up.

We appreciate all the advice you've given, & have a copy of your SOC/V readout sheet in with the rest of the manuals :)

cheers

Sue

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Hi Russ

had a good chat with Tom @ the factory this morning as the monitor reading hadn't come up to 100% after being connected to 240v for 44hrs.

The monitor is still only reading 93.8% & still flashing in the boot. It seems batteries the are full & we should sync tonight & do so every 2/12 or so. Last sync was <1 mth ago any way.

This is our 1st experience with vans so we're still learning as new things prop up.

We appreciate all the advice you've given, & have a copy of your SOC/V readout sheet in with the rest of the manuals :)

cheers

Sue

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Hi Sue, We have been on the road for almost 5 months in a brand new van and are experiencing the same problems that you have outlined. Our van has a Zantrex charger, regulator and monitor so they should work well together. The problem you mention has happened to us when we have been on a powered site as well as when we have been free camping. I have synchronised the monitor a couple of times which brings it up to 100% but it reverts to a lower reading after a day or so. We are currently in Hervey Bay on power and the monitor hasn't shifted off 100% which is how it should operate. I will be asking Kedron to check out the system when we return in September.

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Hi,

Thought I'd add my two bob's worth.

My understanding is that the SOC (State of Charge) is simply an arithmetical estimation of what's gone into the battery system and what's gone out expressed as a percentage of the 'full charge'. There is a likelihood that the sums don't always work out correctly because there is an unaccounted for error (which has a name - see a previous post by Grahame, I think) so that in time, you will always get a reading for the SOC of less that 100% even when the batteries are well and truly fully charged. Hence the need to manually synchronise the system so that it reads 100%. My last Kedron I had fitted with a Phoenix smart charger that would auto synchronise from time to time but I find that I often have to manually synchronise this Xantrex system in accordance with the User Manual supplied.

Cheers

Brian

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Hello,

And I thought I would add my bit as well. I monitor the flashing green light in the boot. When it goes solid it meand the batteries are full so I go into the van and do a sync to have the monitor showing 100%.

We are about to leave Kununurra having crossed the Gibb. Great trip. Headed up to Darwin before folowing the Savannah Way back to home in Cairns.

Regards to all

Colin

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Hi,

Thought I'd add my two bob's worth.

My understanding is that the SOC (State of Charge) is simply an arithmetical estimation of what's gone into the battery system and what's gone out expressed as a percentage of the 'full charge'. There is a likelihood that the sums don't always work out correctly because there is an unaccounted for error (which has a name - see a previous post by Grahame, I think) so that in time, you will always get a reading for the SOC of less that 100% even when the batteries are well and truly fully charged. Hence the need to manually synchronise the system so that it reads 100%. My last Kedron I had fitted with a Phoenix smart charger that would auto synchronise from time to time but I find that I often have to manually synchronise this Xantrex system in accordance with the User Manual supplied.

Cheers

Brian

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