Sorry. One more battery question

[pastordon]

Looking at the post on batteries, how does being idle for the winter months effect the agm batteries as compared to the "regular" led acid batteries. Is there a difference?

[cj_calva]

Hi AJMike
Huuhh, batteries... it's not always easy and you have to try it. Yes, this is right: You have to buy and try of that what you think is the best for you money.

Ok. For the Winnebago Fuse I recommend not a High-End LiFePO4 Battle Born solution. This is still too expensive. There are various AGM batteries on the market which are quite good. Try once the VMaxTank SLR 125 with 125Ah which should fit in your Fuse (Group 31). At Amazon this battery should be around US$ 300.
As the lead plates are closer together, the life expectancy is not as long as with other AMG batteries. But it should last about 5-6 years minimum.
Together with the energy saving methods already posted in the previous discussion (such as running the refrigerator at 41°F instead of 37°F and avoiding direct sunlight on the side where the refrigerator is mounted) this power should be sufficient to run the refrigerator as well as TV incl. DVD in the evening.

Let me tell you that I have a small chalet up in the mountains. I run a 25 years old 25W solar panel with one(!) 120Ah (14 years old) deep cycle battery (lead acid fluid) for light and a 12VDC fridge and charging the laptop and mobile device; DC charging controller, that's it. Never had any problems or was out of electric power. So 200-250Ah in a Fuse should be good for watching a nice movie and get a cool bottle of wine out of the fridge.

[cj_calva]

Originally Posted by pastordon

Looking at the post on batteries, how does being idle for the winter months effect the agm batteries as compared to the "regular" led acid batteries. Is there a difference?

Well most important is that lead-acid batteries are kept being "busy". So there are several smart battery devices on the market (cost about 20US$) which charge and discharge the batteries, so that the battery lives longer.
The difference between the AGM and fluid lead acid batteries is not the chemical reaction, it's the way you put on the acid on the lead.

You should also know that you should keep the batteries in the vehicle (a battery don't like to be moved out of its place, this can build sulphur between the lead slats) disconnect it from all rv-devices and put on an smart charging device. If you don't spend the winter time up in Alaska the batteries will not be damaged by the cold temperatures. Batteries are made to survive -60F.

[AJMike]

Originally Posted by hoosierrun

I did make a quick edit to state for the 60 amp DC to DC charger, 60 amps is really not the output to the batteries. That rating (at least for the Sterling model) is the maximum that the charger will draw from the alternator. There are losses in the conversion and cooling fan, plus as mentioned, your refrigerator will suck some amps (my old Dometic draws 13 amps) that takes away from battery charging amps.

On another board, I have been hearing reports of people with the 30 amp charger only getting 9 to 13 amps of charging capacity to the actual battery (refrigerator, other 12 volt draws, plus efficiency losses). Don't cut yourself short based on manufacturers misleading data.

Perhaps it depends upon the DC-DC charger manufacturer and how they rate their device. For Renogy the rating of 40 amps means that it outputs 40 amps, not that the alternator supplies 40 amps. If the batteries are Lithium and being charged at 14.4 volts, then the draw on the alternator would be higher since more current would be required to boost the voltage from 13.6 to 14.4 in what is essentially a transformer.

As for the current draw from the fridge, the one in our Fuse is a Norcold DC0061 which is a DC refrigerator and to the best of my knowledge draws something like 5 amps max. I don't have that value from an actual measurement since I only now have had a battery meter installed, but that is what I have read on the forums as the draw of the RV fridge, so our current draw should be far less than yours. Still, with the efficiency loses and the extra current required to boost the voltage I assume the alternator might be supplying close to 50 amps for a 40 amp DC-DC charger.

All guesswork at this point, of course. I should have more information if we can ever actually get out camping again ...

[DavidM]

Norcold specs show that the DC0061 draws 3.2 amps which is very good for a 7 cu ft unit. 3.2 amps at a 50% duty cycle is about 40 amp hours a day.

I can live with that easily with 200-300 watts of solar, two 100 Ah Firefly or LPO batteries, an hour or so of genset running time on cloudy days and chassis alternator charging while driving 4 hours to my next campsite every 2-3 days.

David

[AJMike]

Originally Posted by DavidM

Norcold specs show that the DC0061 draws 3.2 amps which is very good for a 7 cu ft unit. 3.2 amps at a 50% duty cycle is about 40 amp hours a day.

Interesting.

It has been impossible for me to know with any certainty what our compressor fridge uses overnight since we also ran the DVD player and the TV and since I did not have a battery monitoring system installed. I would have thought that the fridge uses a bit more than 3.2 amps when on, but I assume Norcold knows better than me what it is actually using.

If we can ever get back in our RV dry camping I will be able to verify Norcold's figures. I would stick the RV in our driveway and check except for the HOA's restrictions where we live.

[al1florida]

Originally Posted by pastordon

Looking at the post on batteries, how does being idle for the winter months effect the agm batteries as compared to the "regular" led acid batteries. Is there a difference?

I really doesn't matter if you have AGM or Flooded Cell lead acid batteries. They do best if they are kept pretty much fully charged all winter long. If you don't have elect at the RV storage, you should get the batteries charged up every 4-8 weeks. Many people pull the batteries, bring them home and put them on a trickle charger in the garage.

Also be sure to disconnect the battery from the RV when in storage so you don't have the phantom drain kill the battery. Keep in mind that even a small 0.5 amp drain will kill a 100AH battery in about 8 days. (0.5amp drain is 12AH in 24 hours).

[DavidM]

There is quite a difference between conventional flooded lead acid (FLA) batteries and AGMs when in storage with no charging source hooked up. FLAs can self discharge at 10% per month or more whereas AGM only self discharge at 1-2% per month.

So I do disconnect my FLA battery on my current camping trailer and bring it home to keep it charged up on a trickle charger for the winter. If I were using an AGM I would leave it on the trailer but disconnect it so that parasitic loads didn't run it down as noted above.

David