Thread: 12V setup for camper trailer.

Originally Posted by drivesafe

First off, hi Doc and not taking a deep cycle battery below 50% is a myth.

All deep cycle batteries have always been able to be discharged down to 30% but all modern deep cycle batteries can be safely discharged down to 20%.

I would be interested to see any documented proof of this from battery makers etc. that their deep cycle battery's can be run down to even 30% of charge on a regular basis and it won't dramatically shorten their life span.

Having many mates who run their fridges off of AGM battery's in their campers one thing I have noticed is while most have some sort of solar charging system fitted nearly none of them have a regulator that tells them what charge their battery has in it and or at what rate the power is being discharged or charged for that matter.

I understand that the only true way of measuring a battery's actual charge is to wait several hours after charging and with no draw down happening but still having some sort of measuring system is better than nothing because it still gives you an indication.

We have a ProStar 30 regulator fitted in the Caravan and it shows you everything you need to know including charge rate, discharge rate and what volts you have in your battery. If you have a good solar system it will also show you when your battery's are fully charged and the system is floating. I have attached a YouTube video of one being used, it is being used with 24 volt but forget that and much of what old mate is saying however it shows basically how it works and what you can see. Below is a chart that if used in conjunction with a regulator like the ProStar 30 that you can see how far down you are running your battery's. The regulator goes into float at 13.4 volts from memory, which even after a big night of using heaps of power it usually is in float by 9:00amish the next morning in late spring, summer and or most of autumn. If you don't have a reliable system that can show you this info then how would you ever know if your system is adequate or not?

[ame]https://m.youtube.com/watch?v=ApcU-Ne3K6k[/ame]

Good points Terry. I just use a cheap ebay voltmeter to monitor the voltage and my solar controller shows when it is actively charging or float charging the battery. I know the current draw of my appiances and what sort of voltages I can expect in the morning before the solar kicks in for the day.

Once you know how your system performs, you become less fixated on amps in and amps out but yes, you should have something in place that allows you to understand what's going on.

I can't help myself, I wake up in the morning and straight away look over to see if the green light is flashing or not to indicate its on float.

I have worked out what every appliance and light in the van uses power wise after turning them on one at a time and watching the regulator go through its cycles.

Even though we have two 100amp AGM's when the van had normal bulbs fitted you could almost watch the battery's drain away before your eyes it happened that quick if they were all on. Now with LED's fitted even with every light on inside and out it only draws about 2.5 amps.

So Bacicat, are you saying that if your fold-up panels have a regulator fitted it should be moved to near the battery? It makes sense because of the voltage drop on the leads. Jim

The regulator should be fitted as close to the battery's as possible.

Originally Posted by jx2mad

So Bacicat, are you saying that if your fold-up panels have a regulator fitted it should be moved to near the battery? It makes sense because of the voltage drop on the leads. Jim

Yes - for the reason you said. They all come fitted with the controller on the panel, but you will be able to run a longer lead with less voltage drop if you mount the controller near the battery. The unregulated output of the panel is quite a few volts higher and every little bit helps. It's also easier to see what the reg is doing at any given time if you place it somewhere easy to see rather than having to tilt the solar panel up if you want to take a peak.

Originally Posted by TerryO

I can't help myself, I wake up in the morning and straight away look over to see if the green light is flashing or not to indicate its on float.

I have worked out what every appliance and light in the van uses power wise after turning them on one at a time and watching the regulator go through its cycles.

Even though we have two 100amp AGM's when the van had normal bulbs fitted you could almost watch the battery's drain away before your eyes it happened that quick if they were all on. Now with LED's fitted even with every light on inside and out it only draws about 2.5 amps.

Ahh - LED lighting - hasn't that transformed camping.

My 2 strips under my awning draw just over 2 amps and the ones inside a bit less. I don't feel guilty leaving them on for ages. I used to have some small incandescent globes years ago - just indicator globes, but at nearly 2 amps each, you had to be content to work with much less light.

Hi Terry and you WILL shorten the life span of any deep cycle battery if you take it down to 20% on a regular basis.

To get the maximum life span out of a battery, or more accurately, to get the maximum energy through a battery over it’s life span, you should not discharge it lower than 80% to 65% depending on the make and type of deep cycle battery.

As I posted, this “50%” is nothing more than a mythical number plucked out of thin air and has nothing to do with life span of batteries.

If you were living the type of life style where you depended on your batteries 24/7, then as above, to get the maximum use from your batteries, 65% to 80% is as low as you should allow your batteries to get.

This is an RV thread and a question relating to RV use. As such, someone trying to work out what sort of use, based on expected life span, can factor in safely discharging the battery down to 20% SoC ( 11.58v ) and getting a good life span from a battery.

If you factor in cycle rates vs discharge level vs “Expected” life span of a battery, you get the real world use of a battery.

If you look at page 8 of the Fullriver manual, the cycle rate at 50% ( 12.06V ) discharge level is around 1250, but as pointed out, by cycling the battery down to 20% SoC ( 11.58v ) you will only get a little over 750 discharge cycles.

Now to the “Real World“ use of a battery.

If you use this battery every day and discharge it down to 20% every day, then you would be lucky to get 2 years use from the battery.

If you used it every weekend, and every weekend you discharged down to 20%, your “expected” life span is now 14 years.

If you only use it once a month, your are now looking at an “expected” life span of of over 50 years. NOT LIKELY!

If you get 6 to 8 years out of most deep cycle batteries, you are doing well, so the governing factor for how low you can discharge a battery and still expect a decent life span is how often you actually plan to use the battery, not some mythical 50% discharge depth.

Here are some links to where the battery manufacturers state discharging their battery to 20% SoC is safe.

SPECIAL NOTE, while these documents are a good guideline, they are “BATTERY SPECIFIC” and you need to get the specific data for your specific brand and model of battery, as every battery is different.

Deep Cycle Battery, Mazda & Truck Battery

Battery Maintenance | Trojan Battery Company

[ame]http://www.fullriverdcbattery.com/media/pdf/technical/installation_manual.pdf[/ame]