pianotuna wrote:
Hi smoline,
With 230 watts of solar I would not increase the battery bank to more than 400 amp-hours, or I would do "bank switching". Two banks of 300 each would allow equalization on each using solar. Lifeline uses the word "conditioning" instead of equalizing.
For heavy inverter use 12 volt jars do have an "edge". I'd consider using two 8 D AGM's if you can find room for a rack to be welded under the Sprinter.
Best bang for the buck still remains flooded cell. Watering when mounted under the RV becomes an issue. There are watering kits available but they cost nearly as much as a battery. Since that is so, you are now in the "price range" of AGM.
If you have deep pockets consider the Edison battery because depth of discharge can be 80% on a regular basis. I don't know if they need equalization or not. There is a firm in Florida which makes them.
230 watts is going to harvest about 1 kwh per day (or 80 amp hours) in June. Parasitic loads will "dine" on about 30 amp-hours. That leaves 50 amp-hours for all other uses.
My coffee pot uses about 5 amp-hours per brew. The toaster about 9 amp hours. The microwave consumes 2 amp-hours per minute. The induction cooker about 1.5 amp-hours per minute of use. A breakfast of bacon, eggs, toast and coffee consumes about 30 amp-hours. So with a harvest of 50 amp-hours net, one can do one meal electrically per day
My guess is that with only 230 watts of solar you won't be able to use the inverter much at all without dipping into the battery reserves.
I chose to have an extra large battery bank (with bank switching) and when I was part time this worked well for trips up to a week. In the time between trips the solar would return the bank to full capacity. Now that I'm full time I have to run the generator, or find a plug in.
I don't attempt to fully recharge with the generator. I use it for opportunity charging when I'm running an electric heater to warm up the bedroom, or using the electrical appliances in the kitchen. I've used just 53 liters of propane since Feb, 2014. (filled up the last week of September). Almost all of that was for running the fridge.
Once it became too cool at night (5 c) I'd run the generator for a total of about one hour. It does have remote start (and stop) so that represents three 20 minute run times.
The solar system works well and has great low light capabilities--but I need to either add to it (say 1200 watts more), or start over and build for 1500 watts.
I'm considering putting solar panels on to replace the awning. There may be a width issue.
My house battery banks are getting old in the teeth--four of the batteries are nine years young, and three are now five years old. Because I'm in a class C, I chose to use marine batteries for all places--so my starter battery is also marine. I'll keep on using them until I have a failure. Because of the cold, LI is probably not an option for me, so I have to decide between trolling batteries or AGM.
I don't expect to replace the batteries again for the remainder of the time I wish to RV.
My big purchase this year was a hybrid inverter. BFL13 has found a 2000 watt hybrid that might suit you as an upgrade.
Don:
Thank you so very much for the details in this post. I look forward to discussing this in as much depth as you will allow.
My current setup in addition to the 230 W solar array includes the two 6-volt AGM batteries that produce 190 Ah plus the Onan propane generator of 2.5 or 2.8 Kw (I forget which) and 1250 W inverter.
With that said, an increase to 400 Ah would be phenomenal; more than double what I currently have and certainly enough to run a coffee pot, toaster, CPAP machine, etc (albeit not all at the same time). However, conditioning or equalizing would not apply, as AGM batteries cannot (or should not) be equalized. I believe the wisest option would be to add more 6-volt AGM batteries to the current setup, or replace the current pair and start anew.
As with Lithium-Ion, I have also researched Edison (nickel iron, or NiFe) batteries not only for my RV, but also as a replacement for the battery bank which backs up the solar power for my home. NiFe batteries have many advantages, but (1) they are exorbitantly expensive and (2) they require watering, so need to be placed in a location convenient to adding electrolyte. As far as I know, they do not require equalization.
I greatly appreciate your level of detail, experience, and sage recommendations. Let's please keep this dialog going.
Steve
