RE: How Do I Charge, and Maintain 2 New 6 Volt Batteries???
You might have a way this trip if your father- in- law's rig has a better converter than yours has. You can yank out your batts and take them over to his rig and put them on the ground close enough, and hook them in parallel with his batts using your jumper cables, while he plugs into the Honda.
If you need 12v in your rig meantime, jumper to your truck or use 7-pin.
One problem with gen charging and a charger is-- How do you know when it is ok to shut off the generator? A good rule that forum member smk uses, is watch till battery voltage reaches 14.4v and then let things run for another hour, then shut down.
If you look at the graphs I posted earlier, you can see how that would work out fairly well.
RE: How Do I Charge, and Maintain 2 New 6 Volt Batteries???
OP, your 10amp charger at 14+ is your best option. You also have the Honda's 8amp to 16v if you have the cable set for it, but since you can't use that and run anything else from the Honda at the same time and that will take a long time too, suggest forget that. When the Honda is running take advantage of it being on to run things instead of waiting till you have to do the same things on battery where possible.
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If you have an extra pair of batteries, you get Way More AH value if you put them in parallel with the other pair while camping and they are drawing down. Peukert rules! Doesn't matter if they are different batteries and all that--it is just for a few days.
Instead of using each pair one at a time like that, park the truck close to the trailer and use jumper cables to parallel the two sets of batteries. Or better still if you are using the truck a lot, just put the extra pair on the ground by the tongue.
When recharging by generator if available, leave them in parallel and both pairs will do the 50-90 or 50-80 whatever you do. Once back home of course you will recharge each pair separately to 100% and then go to Float.
RE: How Do I Charge, and Maintain 2 New 6 Volt Batteries???
You are going to be running that Honda for hours and hours since you don't have a charger with many amps. For this trip, just make sure you have gas for the Honda! Next trip, or when it works for you, you can get a better charging set up.
For example here is a graph of the times it takes to charge 220AH worth of batteries from 50% to 90% using different amounts of amp size smart charger
http://i42.tinypic.com/w7ea36.png
RE: Solar Help
No fuse between panels. No fuse between panels and controller "array" side. 15a fuse (or same amps as controller with the 20% margin over expected panel amps (Isc) on pos wire between controller and battery within 18 in of battery pos post.
If you will be able to get at it, good idea to have an on/off switch on one of the wires on the array side of the controller. This is better than on the battery side because then the controller stays powered up and keeps any settings when you switch off.
Sometimes you want to check battery with no charging happening that screws up your readings, so good to be able to switch off solar. Also when batteries out, so you don't leave the rig loads right on solar with no battery there--can be bad for some controllers. So switch off solar before removing battery.
Controller goes close to batteries for least voltage drop, but not a show stopper if farther away.
If putting controller close to battery then don't waste money on one that has read-outs on it for amps and volts, since you won't be able to see it :)
RE: Solar Help
The OP has only a small battery bank and low daily AH usage, so IMO he could get by fine with just the one 90w panel. (as a portable so he can prop it up pointing towards the sun when parked)
Whole thing would be under $200. (Here, with no shipping, it would be $107 for a 100w panel and $29 for a 10a controller = $136 tax included)
Or you can go crazy :)
RE: Battery disconnect when plugged in at home?
Proper float voltage depends on temperature. eg, at 80F =13.2v and 50F =13.9v When it gets cold you can get into the mid-14s
So any charger that has a steady Float voltage will be mostly wrong. If it has too high a voltage for the temp, then you will need to add water to the batts as required--keep on that and you will be fine.
If the Float voltage is too low, then your battery will stratify and so get sulfated and lose capacity. (but it won't lose water :) )
Time is everything here. If you are only on Float for a few days at a time it doesn't matter.
You have to adjust to the situation you are in what to do. You can get temp compensated chargers for doing your Float if need be. or you can goose the voltage up on the batts every so often to get rid of any stratification happening.
RE: Solar Help
Salvo , yes it is simplified, but the object is to just get a WAG on "expected max amps" so you can pick the amps size for the controller you will need. (You still need to get the input voltage rating business right too so you don't fry the controller with that)
RE: Solar Help
She is fairly good looking, must run in the family.:B
Got a name?
Somebody named her Gertrude. She has been hanging around for a month visiting various sites in the campground for good places to take her naps. She goes for a swim sometimes. Should be finished moulting and go away soon. Her tag number checks out that she is a juvenile female elephant seal.
RE: Solar Help
Flat vs pointed results depend on how high the sun is at the time. The higher the sun the closer flat results get to pointed.
You have the daily sun movement up and down and the annual change in declination change of sun's height, which goes with your latitude.
Soooo---it gets complicated. there are websites that try to show the diff for location and calendar.
I did a comparison last year in May for here using my 130w panel (8.2a Isc) but that would not come out the same in California --being farther south, the diff would be less since the sun is higher down there.
(the dips in tracking amps from 8.2 to 7.7 was due to only moving the panel three times a day instead of following the sun all day)
Time, Flat , Tilted, Tracking- Amps
0700- 1.0, 0.6, 3.7
0800- 2.0, 1.7, 5.7
0900- 3.6, 3.6, 7.3
1000- 5.1, 6.2, 8.1
1100- 6.3, 6.8, 8.2
1200- 6.9, 7.7, 7.7
1300- 7.2, 8.3, 8.3
1400- 7.1, 7.7, 7.7
1500- 6.4, 6.9, 8.1
1600- 5.0, 6.6, 8.1
1700- 3.9, 5.4, 7.3
1800- 2.0, 3.3, 5.7
1900- 1.0, 1.7, 3.7
RE: Solar Help
The OP found these 190w 12v panels earlier in the thread.
http://www.sunelec.com/Specs/Evergreen/ES-A-190_195_fa2.pdf
Isc is 11.8a
Using my formula, 190/130 x 8.2 = 11.98a so that checks out given that the Voc is 22 instead of 21v.
Now we get another 190w panel but this one is a 24v
http://www.windturbine.ca/sun_panels.html
Isc is 5.91 and Voc is 44v (note how Isc is half the 12v version's and Voc is twice)
AFAIK (based on jimindenver) you would still get about 12a with the 24v panel and MPPT (required for the 24 to get it back to 12v and to get the proper amps per watt)
Using just the watts 190 divided by battery voltage of say 13v and rising, you would expect to get 190/13 = 14.6a or a 2.6 amp gain over the PWM version. 2.6/12 = 21% which is the sort of claim you see in MPPT advertising. BUT:
jimindenver gets 15a from his 230w panel with MPPT using a 20a controller (so it does not clip the amps)
Others with 230w panels and the 15L 15amp controller also get 15a but that controller does clip the amps to its rated 15, so it could be they are missing an amp or two. jimindenver example shows they are not. Nobody else has posted "actuals" that would change this story (so far! :) )
The OP has a typo in the amps for his latest find so it is hard to follow. A 90w panel will have an Isc of approx 5.7a so with two, you would get about 11.4a.
RE: Help with calculations: length of time running on battery
You might need a valium then, before going to this link. It has more in other articles in that group linked near the top under "Battery Applicaction..."
Note the discharge side voltage is fairly linear at a steady draw.
http://www.engineersedge.com/battery/specific_gravity_battery.htm
RE: Solar Help
I double dare ya :) Ok.--mena's sister the mermaid in her birthday suit (seen asking about solar panels--on topic!)
http://i39.tinypic.com/t6q82u.jpg
RE: Help with calculations: length of time running on battery
You need to use 10 hours of the 20hr rate to get to 50%. the 20hr rate is just the battery AH rating divided by 20. EG 232/20 =11.6a or 100/20 =5a
the 20hr rate is different for each amount of AH capacity rating.
Now you want to know the time for different amps instead of the 20hr rate, starting with knowing the watts.
Now it gets sort of ugly. The voltage of the battery keeps changing when it is being used , so the amps change if the watts stay the same.
If you use light bulbs though, they get dimmer when voltage drops, so their amps go down! To keep the same amps you have to keep turning on more lights as the battery goes down. :)
OTOH an inverter load will have amps creeping up as the inverter maintains the watts while voltage goes down.
So ignoring that ugly stuff, pretend you have steady amps and that battery voltage is your pick- a- number like 12.4v for your spreadsheet info. Now you have the amps to use for the various watt loads.
With those amps, you compare with the 20hr rate amps using Peukert (ok it just got ugly again) But--to make it easy to do Peukert, now you can go back to that US battery table linked above to see how that would work--not forgetting about you going to 50% so 10 hrs worth instead of going 20hrs to flat.
RE: Solar Help
We should note that a "17v" panel is so named for its Vmp (?) and that its Voc will be 21 or 22v, but that is also called a "12v" panel since it is for "12v" batteries.
So the same panel can be called a 12v, a 17v, or a 22v panel.
Not to be confused with higher voltage panels like 36v ones that are called "24v" panels except if they are higher voltage to go with 36v or 48v battery systems.
controller sizing depends on not going over their rated input voltage spec from the panel(s), so you need to pay attention what voltage you are talking about. also note that voltage will rise when it gets cold, so allow for that extra amount too when sizing the controller for voltage input.
controllers also have an amps rating, so you do need to have some idea of your expected max amps and allow another 20% margin on top of that.
Nobody tells you your expected max amps for any given wattage of panels--except me! :) here it is:-
use the same for either PWM or MPPT, they are nearly the same for this purpose:
expected amps = chosen wattage/130w x 8.2
EG, 230w/130w x 8.2 = 14.5a (jimindenver gets 15a from his with MPPT)
EG 80w/130w x 8.2= 5a (the Isc of an 80w panel and what I got with my 80w.) It works and its free! You are welcome.
RE: Help with calculations: length of time running on battery
This would be part of the puzzle, but you need to know the AH capacity of each battery type there at its 20hr rate. eg a U-2200 (see 6v table) is 232AH at its 20hr rate (which is 11.6a)
Also note they go to flat instead of just down to 50%, so halve the times if they do that
http://www.usbattery.com/usb_images/USB%20Ampere%20Chart.pdf
RE: Solar Help
PT is confusing matters by not explaining. Panel voltage is the same as battery voltage with a 12v system. As battery voltage rises the spread between battery voltage and panel Voc spec voltage shrinks, reducing amps.
With lower battery voltage (and so panel voltage) the spread is large and amps can flow.
However, you don't want those lower voltage panels they had for a while with only 32 cells that were "15v" instead of "17v" like 36 cell panels. those lower voltage panels could not charge RV batteries to 14v because the spread was too small between 14 and 15 so they went to 17 to get more spread so battery voltage could rise to where it needs to go.
BTW, with a B and roof real estate "issues" you might be better off with 24v panels and MPPT for the amps you can get in that space, but it will co$t you for that MPPT. OTOH a B can't carry many batteries, so you don't need that many amps perhaps.
RE: Solar Help
The volts should remain the same 21ish for all 12v panels. You may be confusing 24v panels with 12v panels. Note that Isc on 24v panels is half what it would be for equal wattage 12v panels (natch! :) )
You don't use PWM with 24v panels and a 12v battery system, you use MPPT (big bucks!) controllers with 24v panels to get 12v out to the batteries. Also the MPPT makes its own amps so the 24v panel amps specs mean absolutely nothing
You don't use Imp when on PWM. Use the Isc with 12v panels as expected max amps (except in edge of cloud effect when amps spike higher than Isc)
I have a pair of 100w 12v panels that get 6.3a each as Isc. Together (in parallel) they make 12.6a using the one PWM controller. If I had a single 12v 200w panel I would get the same 12.6a from the same controller.
So now you are asking, "How in heck can I figure out my expected max amps when using 24v panels where the amps spec means nothing and MPPT?"
We have reports that 235w 24v panel and MPPT gets 15amps pointed at the sun. This is about the same as you would get with 12v and PWM with 235w worth of panels. "How can that be when MPPT gets you way more amps than PWM?" you ask.
it seems that people might be seeing those half-amp specs on the 24v panel and seeing them double when using their MPPT controllers making 12v output and they think that MPPT is twice as good as PWM? :) who knows? ( I think MPPT is silly for the money it costs unless you have special circumstances, but never mind me!)
RE: Solar Help
Some controllers have temp comp but not remote, so the temp is where the controller is. However, since the controller should be mounted close to the batteries if possible, this can make the temps "close enough" for ambient at the battery.
So far as getting the temp right for inside the battery, that is a whole other thing. Not clear that attaching the temp probe to a battery post does that either.
From what I have seen, temp comp doesn't matter while camping anyway. That would be more of a Float, storage requirement unless you are camping in winter in Regina or in summer in Death Valley :(
