Being able to equalize Via solar does necessitate a higher wattage to capacity ratio too, and very light usage the night before, unless a generator is run for long enough powering a capable charger in the morning to do the bulk work.
Fill the roof with solar, but the battery tray could still be too large if solar is to be the main/ only recharge source.
As JID indicates, doing it right the first time is much cheaper than doing it right the second time, when upgrading requires different equipment or fatter wiring to accommodate the upgrade.
It is far too easy to have too little solar.
Too many Newb's do calculations as if a 100 watt panel makes 100 watts sunup to sundown, where instead a flat mounted panel might reach 90 watts for 3.5 hours around high noon near the summer solstice.
I've taken a different track with regard to my capacity/solar ratio's. There is a lot of 'capacity is king' mindset on this forum, and I am not one of them.
My rooftop is maxed out solar wise, So I lowered my battery capacity so that the solar could at least approach the battery manufacturer 'recommended' initial charge rate of 10%, or 10 amps per 100AH capacity, at high noon..
Even though this single 31 battery was cycled deeper than 2 27's, I got a better cycle per dollar ratio from it, and I never needed the extra 100Ah of capacity as a bad weather buffer.
Of course being able to go home and plug in and stop cycling the batteries requires a different amount of solar than a full timer too.
I don't think it is just a matter of replacing the AH used +~10% more, but having a higher wattage to capacity ratio. The happy battery is the one whose properly programmed solar controller decided to float it at 11AM on that gloriously sunny day. Not so gloriously sunny, hopefully float by 3. Cloudy, at least it will negate some daily usage.
Any solar is better than no solar, but a proper amount of solar for ones battery capacity ultimately makes for a happier battery. In my opinion, and experience, full timing.
The MV-50 can be made into a very good tankless 12v compressor with a little spit and shine. Just removing all the leftover mold flashing over the air filter inlet holes works wonders.
Mine now has 1/4 NPT fittings, and a 80MM fan blowing over the motor and head. I have 10 awg wire going through 45 amp powerpoles with multiple well wired receptacles to choose from. These are easy to open up and fine tune.
I'd like to have a small tank I could fill when desired.
Mine still pumps my airbags upto 100PSI regularly.
I've got a porter cable pancake compressor for woodworking related projects. It too needs loving to perform well, but its pressure regulator is non adjustable with pressure in the tank. Not too hard to work around.
My inverters couldn't power it and I would not carry it around unless for a job. The MV50 is small, and capable.
My preference order is flooded 2 volt....
.....because 3 group 29 12 volt will always outperform 2 golf cart batteries.
And my preference is the Bugatti Veyron, no other sports car will do. I release flatulence in the general direction of anything else calling itself a sportscar, as i know what is best
Group 29 screams wally world battery. While 3 12v jars will be able to power a high load through an inverter longer than 2 6v batteries, the 6v GC batteries are at least a true deep cycle battery, and designed to be cycled, not a compromise.
Not just a wally world johnson controls battery with extra special marketing made as cheaply as possible.
Good luck in your search
Mex, Not sure if you were referring to me, but I upgraded the aluminum 12awg wire to 8awg tinned marine wire on my GT power meter which does measure watt hours.
There are many such devices available.
I have two of them, rewired, and they do not agree with each other as close as I would like, when plumbed inline.
It can only count current flow in one direction, and only counts so high before flipping back to zero.
Even with the 8awg I would not pass more than 40 amps through it for any length of time.
The screwy 31 sure needed a lot of extra energy forced through it to get to near maximum specific gravity. However if this was not done, performance suffered, and ultimately ~465 cycles is not a horrid figure for such a battery Mostly the extra energy was derived from solar so it was not as if the energy company made any extra profit.
As it was likely one of the better 12v deep cycle flooded car jars available, I'm done with cycling car jars, and modifications are being made to accept a taller battery.
Interesting that the guy who for years has proudly proclaimed his preference for 12v jars is now on a 6 volt benderquest.
While there is little debate in my mind that 6vGC flooded batteries are vastly superior to flooded 12v car jars in deep cycle applications, I always wondered if the 6v AGMs GC's have the same benefits over the 12v AGM's when deep cycling.
I tried to find previous threads where this was touched upon but we all know how easy it is to find a specific thread with the site's search function.
Use the 'direct' link:
This works for me too. PB annoys me when trying to find a pic i uploaded a while back, but recent uploads are easy to find.
Put a proper fuse on trailer side and on the engine battery side of this connector:
I wouldn't want the 7 pin connector to be responsible for trailer battery charging.
One day I noticed my fuel pump was a a lot louder than normal.
About 150 miles later, with 25+ gallons of gas in a 35 gallon tank it quit.
I was in Baja. A local farmer helped me drop the tank just off of Mex1.
My buddy has a Chevy Astro with a pump just as loud as mine was before failure. Been just as loud for 10K miles now.
My little GT power meter I have on my Meanwell counts Watt hours. i have another one I can use on any circuit where I have installed 45 amp power poles, such as to the DC to DC converter powering this laptop.
The voltage drop under load is rather significant on this circuit, and the amp hour figure is likely way off compared to the watt hour figure, in how it relates to AH taken from the house battery.
Too bad my mind was trained with Amp hours instead of watt hours. Relearning will not be easy.
That constant change of voltage under load or charge really throws AH figures out of Whack. Ballpark is mostly fine, but hardly precise.
Journeyman7, I already have 3 inch ducting and many 80MM fans for my CAI for the alternator which I never fabricated. It will be a matter of making shrouds to mate them for a closed system to keep the T 1275 bathed in outside ambient air rather than underhood air.
It would be interesting to Autopsy the 31battery, but it is worth more to me as a core charge for the T1275. The bottom of the cells heating due to plate powder accumulation cannot be denied. I assumed it would be more a direct short with voltage dropping to 10.5v or less rather than what it shows now.
The IR temp gun has been an invaluable tool. While voltage under load had indicated performance loss, and wide disparity between SG on the 6 cells also indicated approaching battery demise, it was the excessive temperature accumulation under a low and slow solar recharge which raised my hackles and caused me to take the battery out of service before it acquired full IED status.
No voltmeter or Ammeter or amp hour counter or Hydrometer would have convinced me to remove the battery while it still powered my overnight needs, but the IR gun certainly did. The IR temp gun was the fat lady.
The screwy 31 is now resting well away from my Van, never to return to within it except when I go get the T1275, but it might also be delivered for little more than the gas it would require of me to get there and back.
I'll estimate the total number of screwy31 deep cycles at 485, which, for a car jar pseudo deep cycle, is not that bad, in my opinion. $ per Cycle is the lowest of all previous sets of batteries.
I am liking how my electrical system allows a few flipped switches to accommodate a complete battery removal, with no rewiring required.
I'm really liking the Meanwell rsp-500-15 for the manually adjustable voltage, as it will be doing a lot of 13.6v converter duty, until funds allow me to acquire a t-1275 and return to a 90% off grid lifestyle.
I'm not going to cycle the North$tar AGM needlessly, even though I did last night to see how well it performs. It appears to still have well more than its rated capacity 18 months into use.
As far as the 31 battery heating up at the bottom goes, the IR gun read hottest about 3/4 inches from the very bottom of the battery, and it was cooler below this part. the hottest cell was the cell which always read the lowest SG wise.
It could have been the cooler asphalt removing heat or just heat generation 3/4 inches up.
The 31battery now reads 12.62 volts 20 hours after it was removed from charging source. I had allowed it 14 volts and amps had tapered to 3.3 when I removed it from charging source, so it was not fully charged
So the 31's specific gravity on last check was reading in the good range on all cells with those extremely elevated electrolyte temps.
Resting voltage is still healthy enough.
It could/can still power my overnight needs.
It was only the temperature the battery was attaining during a maximum 10% recharge which caused alarm bells to ring.
The filled hydrometer was not even cloudy or gray!
It seems that 3 of the 4 regular indicators of battery death, were not indicating battery death.
If I chose the ostrich approach to this battery, perhaps it would have gone boom.
I wish I had a longer 8 awg powerpoled extension cord. I'd continue to cycle this battery further from my Van.
The heat at the bottoms of the cells would indicate it is shorted out, the voltage does not.
Niner, trojan's group 31, the link you posted, was what I was going to go for for a direct performance, and longevity comparison, to the screwy 31.
But, It is still the car jar compromise. The T-1275 would appear to be the smallest of the real deep cycle batteries available.
Trojans 31 terminal placement would also likely have needed modification to accommodate height, and the extra 1/2 inch on the length on each side for the handles could have posed a fitment issue requiring one of them be ground off.
The place where I can get either trojan, lists both the 31 and the 1275 at the same price, 175$
As far as I am concerned, the 31 is not an option. the t1275 will be made to fit, and will have protection from engine compartment heat.
Regarding terminal placement, the (+) goes deepest. The (-) will be closest to the hood closing. Individual caps would be better for Fitment purposes rather than the ganged 3 caps, but no configuration is going to allow easy watering or SG checking of the 3 distant cells. There is no other location possible for a real battery. It IS going here. My underfloor tray where my single 27AGM now resides, can fit two 27's, and nothing taller than 9.5 inches.
The battery basically has to be removed for getting access to the three cells. I turn a few 1/2/both/off switches, remove tie down hardware, pull the ground cable off, lift and angle the battery and slide it out a bit, pull of the positive cable, and the battery can be removed entirely, or balanced precariously on the edge of the structure.
This is how it will have to be with the larger heavier t1275 too.
Now an Hydrometer extension tube is possible, and a better method to check level rather than a flashlight and a mirror for the 3 furthest cells could also be pondered.
I cycled my 91AH NS AGM to 50% last night at a rate peukert would come in to play. 6.8 amps to 11 amps from 9PM to 2:30AM. When laptop was shut down, battery monitor read 46AH from full, and voltage rebounded to 12.2v instantly. I switched my Solar off, and when I awoke I turned it back on and plugged in the Meanwell and dialed that upto 14.5v.
It has been taking 45 to 52 amps for 20 minutes depending on cloud cover, for over 20 minutes now. Voltage is still 13.9v.
I've not really cycled the AGM deeply nor paid attention to its voltage during discharge those times when I did cycle it, but it appears to still perform well and apparently above spec. It is the same age as the screwy 31, but only has 30 to 45 cycles on it. Mostly it is an engine cranker, and my engine rarely takes more than 3/4 second to start.
This AGM gobbles up high charging amps like a woman in a shoe store and a daddy warbucks credit card
Thanks westend, please do not jump through any hoops for me.
Yeah, I'm guilty of overfilling. I tried the mirror and flashlight method to estimate electrolyte level on the 3 difficult to access cells, and missed the mark.
I have two friends who are practically hoarders and will see if i can find something i can cut to size which already has two lipped sides. I do have access to a welder though my welding skills are lacking.
The thermal barrier between battery and engine compartment is going to be more like a stiff shiny roll up blanket, or a least something easily detachable.
Thats generous, thanks Westend. The trojan 1275 is wider than any battery tray I found online, and I assume larger than most battery trays in vehicles found in junkyards, but modifications could be made.
I'm thinking the galvanized angle iron with the holes in it for attaching garage doors would make up a nice ventilated perimeter as well as give attachments for retaining hardware and easy attachment to the sheet metal walls in the area.
The location is a bit unsquare on the 2 sides and 2 sides are floating with a support underneath the middle, so its gonna be a smidge more involved and custom than a lipped 13.5 x 8 inch tray. Incorporating A cold air intake/ ventilation is going to be even more involved.
I'll have some time to get this ready, what I do not have is money to throw at it at the moment, or even for the new battery, so My AGM is just gonna pull double duty when I am not plugged in and the Meanwell is not holding it at 13.6v.
I got the first layer of paint in the area today and buttoned it back up so I can drive around in the meantime. My poor horns are located under the battery tray. They were growing cauliflower from some areas and broccoli from the electrical contacts, but still work.
A flat bottomed tray will facilitate insertion and removal.
I might have to recycle something from friend's junkpiles for the tray bottom. I doubt I'll find aluminum flat plate.
I wonder how much CFM is required. Probably not much. A 80 to 120MM computer fan on a snap switch will pull cold air in and force it around the sides of the battery.
How I wish I had a bunch of stock to pick through, and skills to weld aluminum.
Another cycle on the 31. Took 32AH from it last night
I set Max solar voltage to 14.
The battery heated up, from the bottom up. The hottest part of the battery is at the bottom of the weakest outside cell on the (-) side at 92F.
The range is 78 to 92f on the bottoms of all cells, 73.5 to 75f on the tops of the cells.
The asphalt below the battery is 68F and has been shaded all morning to now, so the heating is entirely charging related.
ATM, it is taking 3.2 amps to hold 14V. 2 hours ago this was 9.8 amps.
Regarding my New battery tray,
I think I've got a pretty good idea how to blow ambient air up from below.
Was wondering how much support a battery requires from below its footprint. I'm trying to force ambient air up from the bottom, around the bottom and all 4 sides, so, through the tray vent holes.
Spilled acid Acid containment will be be at odds with tray ventilation.
Yous guys with the t1275's, have you ever gotten much wetness/dripping after a refill, or from some rough driving?
Trying to design an ultimate battery tray since I'm basically forced to start from scratch. But serious budget constraints are also present at the moment. I doubt I'll have new T-1275 to play with in the next month. I'll cycle the AGM and plug in as much as possible. So I got some time to modify the location to allow the t1275 to fit, and be comfortable in its new home.
Any ideas on a good acid resistant paint for the new battery tray?
I wonder about the Plasti dip spray paint or something similar that would insulate electrically.
I do think I can make a thermal barrier.
I do wonder how hot it gets under there while underway. I've never thought to bust out the IR gun and check after driving.
I cut out the old battery tray and brushed some baking soda dissolved in water in the areas below the tray. They bubbled up nicely.
I cleaned the whole area well and applied some Ospho, and will paint it. Tomorrow
The Screwy 31 is now on the asphalt outside my Van. I have some alligator clamps on the end of a 45 amp anderson powerpole on 8awg cabling attached to the original battery cables. This might be the last cycle, but in theory I can just keep cycling it outside my Van.
The original battery tray is not quite salvageable. I'm going to design something that is easy to remove in the future.
There is some wiring to signal lighting, the and the wiper washer motor and the connectors are hard to reach with battery and tray in place. They were in pretty ugly condition.
BFL, my Northstar AGM craves high current recharges and will not do well on low and slow solar. It also costs 330$ and only has 91AH capacity. It could very well be my last AGM battery. If I do go AGM again, it will be lifeline, unless for some reason super high CCA ratings are required. My Northstar makes a great starting battery, which I don't mind cycling, when I can high amp recharge it the following day.
The current battery tray is already compromised, from rust and acid. It needs attention T-1275 or not.
I want a real deep cycle flooded battery, or at least the 12v battery which comes closest to this ideal. The T1275 should be way superior to any flooded 31.
I will make it fit. I'm trying to decide whether to retire the screwy31 today, or just lower charge voltages to the high 13's and monitor temps.
Seems I should just set it aside, for safety reasons.
The red arrow points to where the hood structure rested on the screwy 31. It was painted with liquid E tape.
Here is the hood structure, giving an Idea what type of modification will be required to it to accommodate the T1275 in combo with the lowered tray.
The Indentation the red arrow points to is obscured by the tape measure in that photo.
It won't need to stick out the top of the hood :) Which would be kind of hilarious.
How bout that bulge?
The t-1275 will be so close to fitting just with the lowered tray.
This is not an ideal location for a battery since it will see underhood temperatures. Radiant barriers could be used, and perhaps I could have a small Snap switched fan vent the area for after engine shutdown.