#100814  by Nut17
 Mon Oct 05, 2015 7:51 pm
Having enjoyed the benefits of LiFePO4Y battery power in our caravan for the last three and a half years, the first three years of which I had a 200AH unit from that "Auckland Battery Supplier" and since January this year have had a 600AH pack comprising eight 300AH cells configured in four pairs for a 12v system. The only management system I have had so far is a Votronic Battery Computer/monitor and have limited my two charging sources to a maximum of 14v bulk. I have set the absorption and float levels 13.0 volts so they are never activated. Neither of my battery packs have been deeply discharged and apart from some manipulation during the initial installation, cell balance has stayed almost perfect without any need for intervention.

I agree totally with "scubadoo's" comments and would encourage anyone considering a new rig or upgrading the batteries in their existing rig to seriously consider LiFePO4 prismatic cells. Once you have sampled the technology, you will never go back.
 #100819  by Teardrop
 Mon Oct 05, 2015 8:15 pm
Being in a job where I sometimes see the results of things that go wrong, I am a bit more cautious about the LiFePo4 although I have yet to see any problems, but it is early days. I have fitted one and am confident it will be safe, plus rate it very highly for performance but I think it is definitely worth fitting a BMS system. Not only for cell balancing and battery protection and performance, but also for piece of mind. Never harms to add that little bit of additional protection.

Neville, you know full well that if Steve names the company concerned, he will be jumped on from a great height. He should not be targeted for following forum rules, but I admit its amusing that we all seem to know which company is being referred to.

Dene
 #100824  by Neddy
 Mon Oct 05, 2015 8:40 pm
Any year now, I will want to replace our 200Ah AGM House batteries. They have done admirable service, but now there are several new types of battery on the market that I should consider. My requirements are simple.
Our overnight power consumption is roughly 40 Amphours. Without completely flattening the battery,
I want sufficient capacity to cover the possibility of 4 consecutive days with little or no solar charging.
I therefore require battery capacity of about 200 Amphours. Most of the time this is way more than we need,
but the reserve capacity is there if/when we DO need it.
Here are our options :-

Image

For me, the number of life-cycles is pretty much irrelevant. We use the bus for about 100 days/per year.
With our overnight 20% drawdown, even our cheap Chinese AGM batteries have lasted well over 8 years and will die of old age long before they wear out.

I'm not trying to run a 200 amp inverter. I'm not trying to fully charge my batteries in an hours motoring.
I'm not trying to save weight. I'm not trying to find the cheapest option. I'm not trying to save space.
I am simply looking for the most cost-effective way for us to go. This will not be a difficult decision.
 #100828  by scubadoo
 Mon Oct 05, 2015 9:23 pm
Neddy

Its good to know that we all have differing energy requirements and wants. :TU

I started with a 80Ah 12V LA house battery and 2 suspect paralleled truck starting batteries.
No space for extra batteries without major work.
Overnight typical usage - 60Ah
Currently 365 days per year travel.
Charging batteries to full in less than an hours driving is useful for us.
Weight is important. We are sailing very very close to a class 2 licence requirement!
The single 300Ah 39kg battery has helped. Room to spare!
I think we made the right battery choice for us.
 #100836  by kiwi
 Mon Oct 05, 2015 10:45 pm
The amp hour rating is basically, how many amps the battery can deliver for how many hours before the battery is discharged. Amps times hours. In other words a battery that can deliver 5 amps for 20 hours before it is discharged would have a 100 amp hour rating 5 Amps X 20 Hours = 100Amp Hours. This same battery can deliver 20 amps for 5 hours 20 Amps X 5 Hours = 100 Amp Hours. Reserve Capacity rating (RC) is the number of minutes at 80 degrees F that the battery can deliver 25 amps until it drops below 10.5 volts. To figure the amp hour rating you can multiply the RC rating by 60 percent. RC X 60 percent

also found this info
The life expectancy of your RV batteries depends on you. How they’re used, how well they’re maintained, how they’re discharged, how they’re re-charged, and how they are stored, all contribute to a batteries life span. A battery cycle is one complete discharge from 100 percent down to about 50 percent and then re-charged back to 100 percent. One important factor to battery life is how deep the battery is cycled each time. If the battery is discharged to 50 percent everyday, it will last twice as long as it would if it is cycled to 80 percent. Keep this in mind when you consider a battery’s amp hour rating. The amp hour rating is really cut in half because you don’t want to completely discharge the battery before recharging it. The life expectancy of a battery depends on how soon a discharged battery is recharged. The sooner it is recharged the better.

What does all of this mean to you? That depends on how you use your RV. If most of your camping is done where you are plugged into an electrical source then your main concern is just to properly maintain your deep cycle batteries. But if you really like to get away from it all and you do some serious dry camping you’ll want the highest amp hour capacities you can fit on your RV.

Deep cycle batteries come in all different sizes. Some are designated by Group size, like group 24, 27 and 31. Basically, the larger the battery the more amp hours you get. Depending on your needs and the amount of space you have available, there are several options when it comes to batteries.

You can use one 12-volt 24 group deep cycle battery that provides 70 to 85 AH.

You can use two 12-volt 24 group batteries wired in parallel that provides 140 to 170 AH. Parallel wiring increases amp hours but not voltage.
If you have the room, you can do what a lot of RVers do and switch from the standard 12-volt batteries to two of the larger 6-volt golf cart batteries. These pairs of 6-volt batteries need to be wired in series to produce the required 12-volts and they will provide 180 to 220 AH. Series wiring increases voltage but not amp hours.

If this still doesn’t satisfy your requirements you can build larger battery banks using four 6-volt batteries wired in series / parallel that will give you 12-volts and double your AH capacity.

The two most common causes for RV battery failure are undercharging and overcharging. Undercharging is a result of batteries being repeatedly discharged and not fully recharged between cycles. If a battery is not recharged the sulfate material that attaches to the discharged portions of the plates begins to harden into crystals. Over time, this sulfate cannot be converted back into active plate material and the battery is ruined. This also occurs when a battery remains discharged for an extended period of time. Sulfation is the number one cause of battery failure. The second leading cause of battery failure is overcharging. Overcharging batteries results in severe water loss and plate corrosion. The good news is both of these problems are avoidable. :TU
 #100837  by muzzanic
 Mon Oct 05, 2015 11:20 pm
Yep, Like many tings in life there is always lots to learn.

The more you learn the more you get to understand that you didn't know much in the 1st place.

I'm really liking reading what people have to say, But I can see how it can all be to much info for some to take in.

However others of us like what some would call over the top info.

As for the saying some of us have done it for years & never had a problem, This may well be true, However I know of speeders that said the same about there speeding, Right up until they got them self killed :o

Just because you haven't had a problem, Doesn't mean that it will work for others.

As we have seen in another thread in the last few weeks, Sometimes people think they have got something right, Until it is found to be wrong.

Play it safe & don't run things on the limit or close to it, It's never a great long term plan.

Murray
 #100839  by WoodyZ
 Tue Oct 06, 2015 5:35 am
Murray - you're drawing a very long bow indeed to suggest that there is any similarity between breaking new Zealand's speeding laws and how different people choose to configure and use their RV battery systems.

Steve - your side-swipe at Lithium battery use in RV's has more holes than a colander and your continual denigration of every battery supplier who is not you is rapidly getting old.
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