I have a gt power inline meter. Similar to turnigy. About 25$ 0n amazon. Accurate at o.8 amps and up. Below that and it reads low. Low lower the less accurate. Very enlightening tool.
only counts to 64 ah, then flips back to zero though.
What I find interesting about the Battery tender lithium's, is that they are packaged as a regular 'carjar' at motorcycle sizes, and smaller and designed to be charged without modification to charging systems. These are obviously for weight savings and not really applicable for rv usage as such tiny capacities.
Apparently they do not have a method to prevent over discharge though.
Thoe jumper packs are likely dependent on the main battery not being fully dead, but many videos exist on U tube of v6 and v8 engines being jumped by the jumper pack alone.
I am not sure we can compare a 200 amp AGM jumperpack to a 200 amp Lithium jumper pack though. Obviously it is not strong enough for Diesel or other large high compression engines, but the existence of such a product is a step in the right direction, and part of me wants in. The other part says a 22$ agm will fulfill my current portable 12v needs.
4 days since last post.
I finally cycled the battery deeper than 18 amp hours. Took 42 out of it last night, disconnected all loads at dawn, when reading 12.2v under a 0.4 amp load.
Rebounded to 12.39v 3.5 hours later, so it does appear to be a slight improvement in performance from a similar discharge event on march 18th, but it is also a slight bit warmer outside. I'll try and get a SG reading after the acceptance stage completes later today, if the sun comes out.
Might reprogram the solar to do the US battery 15.3v Float/finish and just keep the AGM outta the loop, to see how the SG holds and overnight performance compares to 14.8v float/finish.
I've occasionally found myself in need of a small portable 12v battery.
I was kind of interested in these small lightweight Non Lead Acid "jumper packs' which claim 200 CCA and also have 12v@2 amp and USB 5v@2a and firstname.lastname@example.org amp outputs
Then I came across this product, thought it was interesting.
Says to limit charging current to 10 amps and no more than 14.8v, but it is a tiny light battery. I cannot find anything about it limiting the discharge to prevent damage but I assume it must have it.
I'll probably wind up with a small AGM for 1/5 the $$ but I just thought the products above could interest RV.net's battery aficionados , and provoke interesting discussion.
I'm wondering how long before the prices drop to realistic for larger capacity Lithium technology batteries
Hey thanks for all the links and info and input.
While I'll be occasionally busting out the turkey baster Hydro, and reprogramming the solar to do mid to upper 15's eq cycle, that is about as much effort/nursing as I will be putting into this 31. I don't have a load tester capable of Mex's regimen.
It does appear that only one EQ charge every 30 cycles is too few though. That 15.3v recommended US battery 'finishing' charge keeps echoing in the background. I just do not want to forget to turn a switch and expose the $$$ AGM to that voltage. Nice to have that option though.
Since achieving 1.280 I have not taken more than 18 A/h from the battery overnight as I've been house sitting multiple pets while some neighbors are out spring breaking. Plenty of sun the next day. 14.6v has been reached by 10 am. It has not dropped below 12.4v under fridge and fan loads and is 12.6v every time I have bothered to look at other times overnight. I don't really have any basis for comparison for this reduced overnight load after this latest EQ cycle.
I think next eq cycle will be 16 rather than 15.5. I will try to dip the hydro and see how quickly the SG declines despite 4+ hours of 14.5+ per day and report back.
My previous sets of 2 27 Crowns would have required more water by this point.
I've got a nitecore I4 intellicharger which will charge most every size liion battery to 4.2v
As well as nimh and nicad aa and aaa. Even at the same time.
costs about twenty bucks. Accepts 12v or 120v input
Sg leveled off at 1.280 on the three easily accessible cells. So I quit and lowered setpoints to 14.6 acceptance and 14.7 float. The agm is now gobbling up 11.4 solar amps. It dropped to 12.41v under the same loads the 31 was dropping to 12.05v under.
I Put all loads on the AGM overnight. The 31 was still at 13.1v come sunup. And shortly after was 15.5v. Now 5 hours later is taking 1.3 amps to hold 15.5v
SG is 1.280. 1.280 1.275
if no further increases occur in an hour I will terminate
eq. Lower solar voltages and feed the AGM.
Well what is strange is that there is very little visible sulfate on the plates. It has been staying in the mid 14's for at least 5 hours each day.
But it is not getting the daily 15.3v USbattery recommended "finishing" charge, out of deference to the AGM and my inability to always be around to flip switches or test SG in the afternoon.
Just checked again. Taking 2.07 amps to hold 15.5v
1.265, 1.270, 1.260. Electrolyte less 'warbly' looking. bubbling more vigorously than before. A shadow inches from the solar panel. Don't know how much longer I can keep voltages in this range.
Battery has been cycled most every night since last report, recharged primarily through solar. Just checked SG on the 31 after Solar went into float of 14.7 after a few hours at 14.5v.
I could not get my plastic hydrometer to shake the bubbles off the float, so busted out the glass One.
1.235, 1.235, 1.230 on the 3 easy to access cells.
No bubbles stuck to glass float. Electrolyte clear. NO obvious water usage since the last time I pulled the cap.
I switched all loads to other battery and I put the solar acceptance and float upto 15.5v on the screwy31. It required 2.87 amps to nearly instantly bring it up to 15.5v measured at battery terminal 30 seconds after switching.
Last night I pulled 50 amp hours out of the 31. It had dipped as low as 11.8v under a 10 amp max load at that point. The load averaged about 6 to 7 amps until that point. Not sure what it rebounded to after switching all loads to the AGM.
In general my overnight usage has averaged 18 to 27 amp hours. I browse the internet on my Smartphone instead of the laptop now, saving a bunch of battery power, also the days are longer.
So the Screwy31 is still meeting my needs, easily, but the low SG and the lower than hoped for voltage, under load, is not reassuring but I will keep cycling it and updating here as it ages.
The Northstar AGM still impresses me, even though it mostly has just been the engine starting battery. Its ability to quickly crank the engine is impressive. It is nearly like an instant start at the turn of the key, even when the engine is overnight cold. If the engine is already warm, it is even quicker, almost scary fast.
Perhaps the "Pulse" cranking amps figure that Both Odyssey and Northstar like to include on their spec sheets is not just marketing doublespeak. I wonder how a flooded battery's "pulse" cranking amp figure would compare.
All I can say is that the engine cranks as fast or faster with the Northstar, than when I had 3 flooded group 27 marine fully charged batteries feeding the starter.
Edit. 30 minutes after bumping the voltage upto 15.5 SG rose to 1.255, 1.255 and 1.250 on the same cells. Cells bubbling fairly vigorously. battery aking 2.42 amps to hold 15.55v. Electrolyte still clear but "warbly" looking like looking over asphalt on a hot summer day.
Shadows are approaching solar panels.
There exists the option of a 12v/120v compressor fridge too. No inverter needed.
These generally are much more expensive than the 120v only residential fridges, but no inverter needed, so there is a ~15% electrical savings right there.
I am not sure how much total difference there would be in battery consumption between 2 equal sized fridges, one residential, and one 12v fridge. I suspect it is way more than the 15% inverter losses, and factor in a little Peukert too.
Perhaps, if less battery, less recharging sources, and less inverter is needed, the cost of the 12v compressor fridge is not any more expensive than the residential 120v only fridge is.
I am rather impressed with my 1.8 cubic foot Vitrifrigo fridge, both as far as internal temperatures and battery consumption.
Anyway, 12v compressor fridges are an option. NovaKool, Vitrifrigo, Isotherm, Waeco are several of the bigger names using the Danfoss/Secop compressors.
Most regular digital voltmeters can read amps, but the circuit has to be opened and current flow through the meter. Most meters are limited to 10 amps. Usually one of the leads has to be moved from one terminal to another. Make sure to move it back before taking voltage readings.
When my Sawafuji powered Norcold compressor fridge failed the current draw had fallen but the duty cycle increased significantly, and one morning I woke up to it gong on and off every few seconds. I think mine failed due to low refrigerant.
A member here, Bob Landry, IIRC, knows the procedure for checking the Sawafuji compressor for compressor failure.
You can equalize you batteries with your 180 watt solar panel, if you bypass the charge controller and the batteries were full or appeared to be when you bypassed the controller. Lots of sun and a several hours are likely needed. No loads can be on the batteries when you do so.
I've ruffled a few feathers on this forum in the past by my distaste for wally world batteries. Perhaps the equalization will work, perhaps you will be looking for new batteries with a label written in Spanish.
I had an Everstart fail in a strange manner at 23 months of age. Normal voltage indicated it was healthy and fully charged, but put a 3 amp load on it and it went down to 9.x volts.
Remove the load and it rebounded to 12.8v in seconds. One would think the Bosch load tester would have found this issue though, in your case.
It was in a hardwire parallel with another battery at the time which was carrying most of the work, but at a lower than expected voltage. That other battery, another everstart, was removed from cyclic duties and lasted another 5 years in an engine starting only capacity. I think I caught it pretty early.
best of luck in troubleshooting. Let us know what you eventually find.
One possibility is the compressor on the fridge is failing and sucking way more juice than when it was new. Do you have a clamp on Ammeter?
Before acquiring a hydraulic crimper, I thought I could get away with using a vice and a carefully positioned die to make a good crimp.
It certainly looked fine. I couldn't pull the wire from it. Therefor it must be fine, right? Good job saving money right?
A year or two later. Hmmmmmm. Why is this voltage lower than expected. Wait a minute, Why is this ring terminal hot? Lookee here the electrical tape is all squishy and messy.
Who the F made this half ass crimp?
Oh it was me, back when I was too cheap to acquire the proper tool.
I had a similar failing with the expansion joint and a cold chisel method, and that SOB was one purdy looking crimp, until it too failed.
About those Automotive parts store premade cables?
Well think again. Those lugs are just crushed steel over copper wire with a hole drilled through both of them. Here are some I cut off after finding that current was avoiding this ground wire. They are sticking to a magnet.
After crimping on some copper lugs to this cable, it shared current equally with its SAE 4awg twin. And 4 gauge SAE is not the same as 4awg gauge either. It is thinner.
Open ended ring terminals with plastic coverings, especially on the battery itself, say all there needs to be said about the workmanship and its intended longevity.
I've had some DC 12v batteries than when fully charged and rested would read 12.8v
I've had others that would read 12.6v under the same circumstance.
I have an AGM battery that reads 13.07 volts when rested and fully charged.
These " universal" Voltage charts that proclaim states of charge are amusing, especially when it is not pointed out that these are rested voltages, not voltages under load.
Now if the voltage/SOC chart was given out by the battery manufacturer for their specific battery, I would put more stock in them, but I would not put any stock in them unless the battery had not seen any charging or discharging source for many hours, unless I had been monitoring them for many many cycles while discharging them in a similar manner.
If someone sees 12.02 volts under a 5 amp load and freaks out cause such and such a chart says it is in the danger zone, well I guess the only damage done is on the person who freaks out and starts recharging prematurely, and this can only be a good thing for the battery, so no harm done.
Unless you fire up your generator next to me.
Last night, 42 amp hours consumed.
Was 11.9v under a 3 amp load (cycling fridge) when I isolated it from all loads before sunrise. Rebounded to 12.34v 4 hours later.
Not as impressive.
This is with a 14.5 absorption and a 14.7v float.
I've not been doing the USbattery 15.3 'finishing charge' in deference to the AGM battery which often is in parallel during daylight.
Last night, I consumed 30amp hours, and was reading 12.12v when I switched all loads to the other battery before sunrise.
3.5 hours later the voltage had rebounded to 12.49. Surprising it rebounded that much.
There is a zillion factors in how much battery power a fridge is going to consume. Ambient temps, heat load placed within, quality of the insulation and seals, quality of the condenser ventilation, how fast the manufacturer decided to run the Danfoss compressor and how well it performs with the evaporator plate the manufacturer decided upon and perhaps another 2 dozen factors.
I gave you the absolute minimum amp draw of a Danfoss BD35f driven at the slowest compressor speed possible of 2000 rpm on a very small fridge. No resistor on the T stat circuit, extra insulation, and a condenser which sees nothing but the coolest possible ambient air temperature, ever. I've seen it use less than 7 A/H per 24 hours with few door openings in low 50's ambients, and I have also seen it consume 36 A/h in 24 hours when I loaded it with warm beer on a hot day and cranked it up to 75%. Unfortunately I forgot to lower it that night and had beer sickles the next day.
I never said this is what your dual 7.5 cubic foot fridges are going to consume. I have no idea how you are going to use them, what temperatures you are going to be in, or what temps you are going to expect internally nor how often you will be opening them, how long you will leave the doors open while you scratch your chin or how often you will be placing warm items within or how warm those items might be. These are huge variables.
YOu sound like you are sizing your solar array with a big buffer. Get the fridges you desire, and you can then tell us how much they consume when running and you can keep a log of the duty cycle, or get an amp hour counter but nobody here is going to be able to give you an exact consumption figure with 2 dozen unknown variables.
I've done nearly everything I possibly can to make sure mine runs as efficiently as possible, and I am thoroughly impressed with the performance, especially compared to the Sawafuji powered Norcold I had previous.
Since my fridge is so small and the BD35f could handle a much larger fridge at higher compressor speeds. I have no worries.
I can also return the resistor to the T stat circuit easily: