Deep cycle 6v charging help

Rich_A

Just found this forum.  Been looking for a good source for "alternate energy" discussions and info.  This site looks to be one of the best I've seen.  I will be spending a lot of time here getting educated .. (I hope)  <grin>  

I'm trying to set up something a little different here than your normal off-grid alternate energy solution.   Recently inherited this property and home that is pretty much off the beaten path.   We are on a small mountain top on a several mile unimproved dirt road in North Central Connecticut.   For the past two years I've been renovating this 70's era home which had been unoccupied for several years and needed a lot of work. 

The most pressing problem here at the moment is short term power outages.   We are in a heavily forested area of old growth trees and our electric service is often interrupted for (mostly) short 1 to 6 hour periods.   So far this past 12 months we've had maybe 10 outages.  These are usually caused by tree limbs contacting the top electric lines on the poles.  Normally the lines are not damaged, but the contact causes the line to be shorted and we loose power until the electric company can find the problem area, remove the tree limbs and re-set the local breakers on top of the poles.   The electric company is quick to respond and because the problem is often very local and in a limited area it is fixed quickly ..  1 to 2 hours at most.   Sometimes we do have (twice now) major storm related outages that last several hours.  In that case because our several mile long road in the mountains only has like 6 people living on it .. we are of course the very last to have our power restored.   I have a whole house external connection wired for  a generator.   (still haven't gotten the genny yet)  

In the mean time, I thought of building some kind of small battery / inverter system to use sorta like a big UPS just for these short term outages.   I only need to keep the Fridge, some electronics, lights and the furnace running.  Rather that running out to the garage to fuel up a generator, hook it up and run a cord to the house hookup (usually in the dead of Winter in a snow storm of course) I thought to just have this battery / inverter backup system in the basement ready to just "plug in" and be okay for several hours. 

So I've purchased two new 6v 215 AH golf cart batteries and have a 3K pure sine wave inverter (12 volt) set up.   When I got the batteries home I checked them and found although they are the same models etc. they were manufactured in Sept and Nov of this year.  I was hoping to get as close to  a "matched" pair as possible.  I found the Specific Gravity in each cell (new out of the box and supposedly fully charged) to be good and close to being equal in one battery.  But the 2nd battery had one cell that was quite a bit lower than the other two.  (I didn't write it down but it was something like two were at 1.250 and one was 1.200 .. So I put on a "cheap" 4 AMP smart charger that was a high freq. 3 stage charger and maintainer.   I've used this charger before on some small SLA deep discharge and regular car 12 volt batteries and it worked great.   But it doesn't seem to be working correctly with this new "suspect" 6v golf cart battery I have.  It has quickly gone into (i think) it's equalizing mode .. and the voltage has been cycling between 7.1 and 7.2 volts for 2 days.   ( Normally when re-charging a 12v battery it goes into it's "equalizing mode if needed" and cycles between around 15v for a couple hours and then drops down to it's maint. mode  of 13.8 or so volts.  

However, during the 6v battery charge, the charger screen stays red and flashes those "top off or equalizing voltages".  It's "supposed" to finish at some point and then turn green and go into it's maintenance (float?) charge (green screen) at 6. something volts.   But I'm now starting into day three and it hasn't finished yet. 

Can anyone tell me what kind of time frame I'm looking at to finish charge a 215 AH deep cycle golf cart battery using a smart charger running at a max of only 4 amps ??   Sorry for the long post .. just trying to give as much info as I can.   I intended to first fully charge each battery individually and hopefully equalize them before installing them in series for the system.   Working on a limited budget but hope to increase  capacity in near future to a series / parallel setup and add solar power to recharge the batteries later.  I'm also now worried about the "gassing" situation while doing full recharging.  At the 7.2 volt full at 4 amps? there IS a little bit of bubbling going on ... (very very little) But I'm concerned.   I figured during normal use, after the power is restored I could have more than weeks or months before needing it again and  could "slow charge" the batteries back up to full. 

jonr

It's a large battery with a small charger.   IMO, this has two effects:   a) the charger is confused and b) you won't get enough gassing to properly mix the electrolyte (wet batteries only).     Solution - a larger charger (perhaps 10%=21 amps, no less than 5%=11 amps).

For example "The recommended charge current is 10%-20% of the AH capacity of the battery bank, based on the 20 Hr AH rate (C20)."
https://rollsbattery.com/public/docs/user_manual/Rolls_Battery_Manual.pdf

BB.

Welcome to the forum Rich,

Sorry to hear about the problems with that one FLA battery. Have you tried a load test on it (or taken it to the battery retailer and have them check it)?

It does sort of sound like that battery is sulfated... Quickly recharging to "full", but perhaps not really full. Do you have the SG readings for the cells after "charging"?

If the cells remain low (or at least one of the cells is "low"--Say 0.015 to 0.030 below a "nominal" 1.265 SG fill), and equalizing does not restore... I would try to get that battery replaced (would be "an easier return" if it "failed" a load test).

Generally, a 6 volt golf cart battery is around 200 AH... If it sat for ~1 month at room temperature not connected to a charger, it can drop to about 75% state of charge through self discharge (the colder the battery is stored, the slower the self discharge).

• 200 AH * 0.75 state of charge = 150 AH of stored current
• 200 AH - 150 AH = 50 AH to recharge
• 50 AH / 4 amp charger = 12.5 hours of charging "ideally"

As batteries recharge, they slow the charging current (charger runs to ~7.35 volts) and the absorb should be held at that voltage for ~2-6 hours (the deeper the discharge, the longer the time "absorb" stage).

So, as a wild guess--The charger should take about 16 hours (+/- a couple of hours) to fully recharge the battery the first time.

To equalize an FLA battery, you need 2.5 to 5% rate of charge...:

• 200 AH * 0.05 rate of charge = 10 amps
• 200 AH * 0.025 rate of charge = 5 amps
• EQ should be around 7.5 to 8.0 volts (you really want to get your ~5 to 10 amps of current flowing into the battery and a pretty good "fiz" going--Not a rolling boil. And if the battery is left on EQ for "hours", it will get hot--And with enough current/time, hot enough you need to stop charging to prevent overheating)
• EQ starts when the battery is near 100% SoC... EQ is basically controlled over charging of the "full" cells, to bring up the under charged cell(s) to full too.
• "Full charge" is when a cell SG stops rising (check cell SG every 30-60 minutes). Some battery Mfg. recommend EQ ~once per month... Others recommend EQ when the difference between the high and low cell SG is over ~0.015 to 0.030 SG units (be careful when measuring SG... gas bubbles can collect on the float and give you a miss reading--And rinse the hydrometer after you are done with a few squirts of distilled water--Old electrolyte can get sticky and cause the float to stick to the wall of the hydrometer).

So, that charger is a bit small to really give a "good equalize" to your battery. But if you need "corrective" EQ on a "new" battery--There is probably something wrong with the battery.

-Bill

icarus

Just an additional note...Your current battery bank is way too small for your intended inverter.  3 kw from 215 ah of 12vdc battery is not gong to happen.  Even a 1 kw load will most likely drop the “apparent” voltage of the bank below the low voltage disconnect of the inverter. Quite frankly, you would be way better off to define the “critical”short term loads, (fridge/freezer/furnace etc) the power requirements for each, guess on the duration of expected outages etc, and then...buy hardware.

For example, a 1 hour outage where you only need to provide heat (because the fridge and freezer will stay cold enough for example) is very different than a 12 hour outage.  Discharged to ~50% you battery will likely deliver ~ 1.3kwh of power, and that is from a comparatively small load.  Try to run a fridge compressor for very long, and, as I said, the battery will drop below low voltage disconnect.

Consider, at a minimum, 4 GC batteries, a 1 kw inverter, ideally an inverter/charger like a Magnum.

As for you current set up, at the very least, get a good four stage charger if you want your batteries to last.

All things considered, for the price of the inverter and the batteries, a Honda Eu2000i generator (or a cheaper clone) would cover most of the essential loads for a long time on very little fuel at less cost and more reliability.

Good luck and keep in touch,

Tony

Estragon

+1 on Tony's inverter/charger suggestion.  Something ~1500w would be more appropriate for a string (maybe two) of GC2 batteries.  A decent one would include the AC charger you really should have, and an automatic transfer switch which automatically switches to battery power when the grid drops.  Depending on the generator, some can also optionally be set up to start the genny automatically.

Just to clarify (maybe I missed it), but is the 4a charger set for, and/or capable of 6v battery charging?  If it's a 12v charger, it may see the 6v as under a low battery cutoff and be faulting?  If so, you'd need to charge it along with the other battery.

Rich_A

Wow,

   Lot's of comments in only a few hours.   This is gonna be fun.   Not familiar with how this forum works.  I'd like to make multiple quoted replies.   You guys have surely responded with a lot of good info and suggestions.  Thanks.   Let me "try" to cover everything.   Some new info first.  (and i apologize for making this a long winded read)   Bear with me.

When I started charging this first battery the SG for  each cell was reading around 1.275, 1.245 and 1.250 per cell.  It's been about 56 hours now, and the cells are now reading 1.275, 1.270 and 1.270  (hard to read the graduations on hydrometer but that should be within a few points)  So it's finally looking better.   But the charger is  still in equalize mode.

I think it's just taking a lot of time due to the conservative design and low amp parameters of the small charger I'm using.

Regarding the charger: 

The charger is a max 4 amp unit .. it's smart and can do SLA Gel, regular lead acid, and deep cycle, both 6v and 12v and is temperature controlled? has Winter mode what ever that is.   It examines the battery and somehow determines if it is in need of balancing, and/or recharging.  I've only used it with various 12v batteries a few times and is still new to me.  (instructions are totally lacking).   Supposedly it's a 3 stage charger .. and when done will go into an automatic maint. mode and I guess trickle charge the battery at 6.? volts.  Don't know what that final volts are because so far I haven't finished a full charge with a 6v battery.  Guaranteed not to over charge the battery and will do any type or capacity but NOT LIon or non-acid types.   But it is very conservative in native and of course only runs at a max of 4 amp during it's highest charge rate at 7.2 volts or 15.x volts when in equalizing mode. And yes I'm got it set for a 6v lead acid battery.
 

I disconnected the charger and will check it with a load test meter later. But an hour after that uncompleted full charge attempt the volts settled down to 6.6 volts at no load rest.    But I'm guessing that battery was probably on the shelf for some time (it has an older manufacturer's date than the other one) before I bought it and it was in dire need of equalizing and/or a good initial charge.  Now the SG doesn't vary more than 0.005 between all three cells.  (as best as my old eyes can read the vague graduations)  So I'm now starting to charge the 2nd battery which is a little lower in total volts, but where the SG of each cell is very close to be the same (almost exactly at 1.200)  I'm hoping that this battery will take less time to do a full charge as the cells are already pretty closely equalized and it shouldn't have to go into it's auto-equalize mode.
  
Also, I was not correct about my inverter .. it's actually a 1,500 watt unit with a 3,000 watt surge capability.
 

Now after reading your (collective) comments, I"m wondering if I might be chasing something that's not practical.
 
Yes I know I could just pick up a cheap knock off Honda inverter generator clone for 6 to 7 hundred bucks.   But money IS an issue at this time.   And the "gasoline generator" doesn't solve the actual problem here.   At 74 years old with some pretty bad recent heart problems I'm hoping to eliminate my having to trudge out to the detached garage where the generator will be stored (some distance from the  house) and dig out the generator, gas it up, hook it up and run a cord to the house and get everything running only to have the power come back in 1, 2 or 3 hours.   

My thought was that a small battery backup system would enable me to keep the furnace, fridge and TV and some electronics going for just a few hours and I wouldn't have to fool around with the generator at all.  In the Winter what with my current medical problems I really don't want to be trudging around in the snow in sub zero weather messing with gas and such when I'm only looking to keep a couple items and some lights running in what most likely only be a few hours at the most.  

I was hoping to only need to use about 1/2 of the 215 AH battery bank for those few hours.  But comments here have made me re-think this. 

It's been a couple years since I first moved up here and during the renovation I did check various wattage's etc. for everything.  All the appliances were bought new at that time and all are tops in energy efficiency.   Since then I lost my notes but from memory I believe the furnace (measured with a clamp on amp meter at the electrical box) saw a bit over 6 amps spike at start up and a regular running load of a little less than 3.5 amps total (@120 volts)  that was for the oil burner and the circulatory pumps for the hot water baseboard heating system combined or about 400 watts.   Last Winter our coldest month averaged 28 degrees per day, and all that time the furnace only turned on for 5 minutes about every hour or actually 25 times in a 24 hour period.  So for that total 24 hour period of 28 degree weather, the furnace ran for a little over 2  total hours.   Not sure about my calculations here,  maybe 800 total watt-hours?  I've lost a few brain cells over the years. <grin>
 
For the fridge, just because I didn't have any notes from 2 years ago I  did a short test earlier today, and recorded the use over a 5 hour period.  During normal run time the fridge was drawing 108 watts and less than 1 amp.  I knew it was a pretty good energy efficient unit and was frankly surprised at how little power it was using.  So I left it plugged into the "kilowatt" meter for 5 1/2 hours and checked and it only drew 0.31 kWh for the entire 5.5 hours.  Of course that was today and it's Winter and the house is usually at a pretty low ambient temperature.  But still I'm wondering if I'm reading the meter correctly or if I'm screwing up my calculations by comparing AC street wattage at 120 volts and DC wattage provided by the battery's 12 volts?   This was second nature to me 20, 40, and 60 years ago.  Now, not so much. 
 
So I originally thought I'd be good to run a few lights and maybe a small LED TV  for a few hours along with the intermittent use of the furnace and fridge and would be okay.  At least for a few hours ?   Shouldn't I be able to run those things for a few hours only using 50 percent of the 215 AH battery capacity?  Maybe I should also consider inverter efficiency, and a host of other things that could affect this.
   
Remember, I'm not looking to go "off grid" with a whole house configuration for days at a time.  I'm only looking to find a quick and easy way to "get by" for those several times a year when I loose power for 1 o 3 hours at most.  I hope I haven't underestimated my energy requirements here.  If so perhaps 4 more batteries with all six in a series / parallel arrangement should give me about 645 AH of which I could probably drain to 1/2 capacity and still have 300 AH reserve left if really needed?   And I still wouldn't have spent as much money as a decent inverter type 2 KW Honda generator.  

But comments here have given me a lot to think about.  Sorry about the "typo" on the 3000 watt inverter.  It's a 1.5 K run and 3K surge unit.   I "think" the batteries are fine and just need good initial equalizing and charge.  But maybe I need more of them ??   Wish I could find my clamp on amp probe/meter so I could check that furnace amps again. 

Oh just had an idea.   My power breakout panel is sorta unusual.  It has it's input line (for the genny) and has 4 three position switches and 4 in line circuit breakers.   Each switch is a single pole double throw .. so there is an ON-OFF-ON switch for each circuit.  One is for the furnace.   Another for the kitchen.  Another for the living room and so on.   So I can actual use those switches to switch from street power to gen. power or also be totally off completely.   I think I can just switch the furnace switch from it's "street" position to the generator position and be able to single out just that feed from the genny to the furnace bypassing the street ??   I "think" that's how it works.  The original owner (my father) had this installed so he could control what and when he could run on generator power.   Anyway, I could use that as is and read the inverter's various readings for power / volts etc being used.   I think I can do that to get a good real world reading of what each "zone" in the house (including the furnace) is using for power consumption.   Any thoughts on that?

I really appreciate and need advise about this .. thanks everyone.   

- Rich A.    

Rich_A

When I leave one space between paragraphs (to make the long text easier to follow and quote etc.) this forum seems to be adding an extra three or four blank lines between each paragraph.   What's up with that ??  

Oh and I forgot ... Bill's comments on equalizing were most enlightening.  That fine tutorial filled in a lot of missing info the charger's manual didn't (and should have covered).   Thanks Bill. 

- Rich A

BB.

Hi Rich,
Yea--Double spacing has been a problem for a few years, but mostly restricted to a few posts/systems (like my android phone with firefox).
I will reopen the trouble ticket and see what happens.
-Bill

icarus

To expand on Estrogon’s point.  For example, a  Magnum inverter/charger is complete with a transfer switch.  When wired to the grid, it will pass current through to the capacity of the transfer switch (usually much higher than the capacity of the inverter output) as long as the grid is up.  When the grid (or shore power or genny) goes down, the inverter will now power what ever essential loads that are wired to it.  It is all very seamless.  When the grid comes back up, the transfer switch once again passes current, and also simultaneously charges the battery bank as configured.

As Estragon also points out, about 1 kw would be the right size for your battery bank.  Once again, define your mission critical loads, and design the battery/inverter/charge regimen around those loads.  Adding solar is of course an option, once again defined by the loads.

Tony

PS.  Your 215 ah (12 vdc) battery bank would like to see ~21-25 amps of charge current to keep it happy.  Too low of a charge current is a way to slowly kill a battery.

T

BB.

Rich,

Lead Acid Batteries actually need to be cycled... One full, it can take dozens of cycling (down into the 75% tio 50% state of charge range) to help "form" the plates and reach the battery's maximum AH rating.

At this point, you can stop the charging. It is probably not doing anything "good" for the battery at this point.

Your SG readings seem to be OK...

Regarding how much current your refrigerator uses... I am trying to be clear here, and if you already know this, sorry to be redundant.

Your refrigerator using 1 amp at 120 VAC... But the battery bank is at ~12 VDC. Remembering our power equations:

• Power = Voltage * Current
• P= V*I = 1 Amp * 120 VAC = 120 Watts
• I=P/V= 120 Watts / 12 VDC = 10 Amps

So, your 1 amp @ 120 VAC motor is actually drawing around 10 Amps @ 12 VDC...

And AC Induction Motors draw (very roughly) 5x current during starting:

• 1 amp * 120 Volts * 5 starting/locked rotor amps = ~600 Watts starting
• 600 Watts starting * 1/12 VDC battery = 50 Amps starting current

Deep cycle batteries can supply (relatively) high surge current... But with all of the stuff that goes on in a solar power system, the recommended maximum size AC inverter is ~250 Watts per 100 AH of 12 volt battery capacity:

• 200 AH battery bank * 250 Watts per 100 AH = ~1,000 Watt recommended max inverter rating (typically 500-1,000 Watt inverter suggested)

And to run a modern full size AC refrigerator is suggested around a 1,200 to 1,500 Watt minimum AC inverter... So, technically, suggesting at least 2x parallel strings of golf cart batteries (12 volts @ 400 AH or 4x GC batteries total).

-Bill

mcgivor

BB. said:

Hi Rich,
Yea--Double spacing has been a problem for a few years, but mostly restricted to a few posts/systems (like my android phone with firefox).
I will reopen the trouble ticket and see what happens.
-Bill

One observation, the double space is consistent with the thread title remaining bold despite having been previously read and when re opened, always displays post #1.as though it hasn't been.

Telling the doctor, (the IT guys) the symptoms will make the diagnosis easier. Hope this helps.

Edit: Once a comment is made the bold title dissappears and upon reopening goes to the latest post.

Estragon

A pair of GC2 batteries gives ~2500 Watt-Hours of total storage.  Although we normally suggest using no more than 50% for best use/cost, in this application a deeper draw may be okay.  Even so, as the bank gets under 50% (~12.0-12.1v), it will get increasingly hard to start surge loads like the fridge and furnace.

Assuming you can babysit the loads in an outage, you might be able to get down to say a 35%SOC and (maybe) still be able to start/run the loads (one at a time).  That gives you (maybe) 1600WH usable. 

Running loads of (eg) 50wh/hr fridge + 50wh/h furnace + 50wh/hr lights = 150w ÷ 75% inverter efficiency =200w.  In theory, if the load numbers are about right, that might get you through many of your outages.  1600/200=8hrs, but the starting load may pull bank down too low before then.  The inverter will likely fault if voltage sags to ~10.5-11v starting a load.  

For the genny, you may want to consider a propane (or converted from gasoline) unit to reduce fuel storage issues.  I think there are some small gennies that can be fitted with remote start.

Rich_A

Estrange said:

A pair of GC2 batteries gives ~2500 Watt-Hours of total storage.  Although we normally suggest using no more than 50% for best use/cost, in this application a deeper draw may be okay.  Even so, as the bank gets under 50% (~12.0-12.1v), it will get increasingly hard to start surge loads like the fridge and furnace.

Assuming you can babysit the loads in an outage, you might be able to get down to say a 35%SOC and (maybe) still be able to start/run the loads (one at a time).  That gives you (maybe) 1600WH usable. 

Running loads of (eg) 50wh/hr fridge + 50wh/h furnace + 50wh/hr lights = 150w ÷ 75% inverter efficiency =200w.  In theory, if the load numbers are about right, that might get you through many of your outages.  1600/200=8hrs, but the starting load may pull bank down too low before then.  The inverter will likely fault if voltage sags to ~10.5-11v starting a load.  

For the genny, you may want to consider a propane (or converted from gasoline) unit to reduce fuel storage issues.  I think there are some small gennies that can be fitted with remote start.

Looks like I made some assumptions based on my prior experiences dealing with emergency back up systems for my ham radio station setup.  Which is all 12 volt.  My station has a setup similar to what was described early in this discussion.   95 percent of the station is powered by an always on large switching 12 volt power supply.  There is an "uninterruptible" switch device that will automatically switches from the AC line powered DC power supply to a small 70 AH SLA battery bank when the power goes out.  This happens automatically.  When the power from the street is "on" the UPS device manages the battery maintenance keeping the batteries properly trickle charged when needed and provides power to run the station.  When the power is "out" the device automatically switches to the battery bank. 

I do have a small 700 watt DC to AC inverter installed to power a few of the 110 volt devices in the "radio shack" .. but I normally don't need to use those devices when running on full battery backup power.  This system was installed when I moved to this home about 3 years ago and has worked fine ever since. 

So I was thinking, how difficult could it be to make something like that system on a larger scale so I could run a few house hold items during a power outlet?   Well I never considered that I was really talking about apples vs oranges ... or 110v AC versus 12v DC.   I should have realized that.   Based on the quoted comments  I think there might be some hope I can salvage my project.

1. I really need more battery capacity as I think in reality my current system might not work for even a one hour run time.
2. I need to address the problem of re-charging the battery(s) in high current mode and deal with gassing problems. 

3. Due to my new (disabled) physical limitations and thinking about using a generator,  I would need to have a permanently installed  auto-starting genny outside the house somewhere.   And that just isn't financially possible right now.  

I do have a couple other battery chargers .. One is a garage 40 / 200 amp commercial roll around 6-12v charger/starter that can provide 200 amps for starting a car if needed.  So I could give these existing golf cart batteries the required high recharging  (up to 40 amps) if needed.   I could financially afford to add two more batteries for a 4 bat par/series arrangement but the normal re-charging and maintenance is going to require handling the gassing problem.  The batteries are in the basement.   So I would have also invest in some kind of exhaust system etc. get those gases out of the house.  

Based on what Estrange said (above) I "might" make this work.  One thought might be to move the whole system out to the garage where it can be easier to "vent" and maintain.  And somehow back feed the power back to the house where the emergency power panel is located?   Ah yeah ... Rube Goldberg comes to mind ... <grin>

- Rich A

icarus

Venting battery gasses is not really too much of a problem.  MY batteries, (4 Trojan T105 GC batteries) sit on a cart under my desk/bench in our little office.  The bench serves as the top of the battery box, the two walls serves as...two walls, and i have a plywood side and a removable front so the batteries are full enclosed.  The function of the cart is to move them out from under the bench to service them monthly or so.  The entire box is lined with foam board to maintain near constant battery temps (except when I leave mid winter!) 

the entire box is vented with a Zepher fan, directly to the outside, with the fan voltage controlled so that it comes on when the battereis are charging at or above gassing voltage, and is off all the rest of the time.

https://www.solar-electric.com/zephyr-battery-box-ventilator-24-volts-dc.html?gclid=Cj0KCQiAt_PuBRDcARIsAMNlBdoLH6HgpU6d7wWjdlIzFyzmea2nEGBEqzf6CdVbabsUlR4LUKddUhQaArypEALw_wcB

This one is 24 vdc, but they make (and our host sells) a 12 vdc version.  Draws ~1/2 amp iirc, and plum is into 2 or 3” abs or PVC DWV pipe.  Very easy to install.

All that said, 2 (or even) 4 GC batteries are unlikely in a large space to produce enough gas to be a real risk imho. 


Good luck, and keep in touch,

Tony

Rich_A

That's GREAT news Tony.  Thanks ... You've made my day !!  As it turns out .. originally there was a whole house central vac system installed years ago here.  It has since been disconnected and removed but the vac had a 2 inch PVC exhaust system that runs to the outside basement wall for exhausting the vac output that is still available !!    I could use the H2 gas exhaust fan you referenced and my battery gassing problem is solved.  It just so happens that the central vac system is all 2" PVC sized tubing which I think is what that fan device has.   In your setup did you have to use any kind of special PVC ?  Or can I just use the existing stuff?  

icarus

In this case., PVC is PVC, is PVC.  It isn’t carrying significant pressure or liquid or corrosives.  I’m just vents about a foot to the wall, but longer isn’t gong to hurt as long as you have flow.  Too many Els and turns might reduce flow somewhat, but probably not enough to matter.  The only consequence of reduced flow will be the fan is going to work a bit harder against the back pressure.

Tony

Estragon

I have my banks (12 x L16 size, roughly = 20 GC2s) in an insulated crawlspace under the cabin.  Planned to vent with something like what Tony describes but haven't got to it yet.  The space is big enough that I'm not all that concerned about gasses.

Before my solar setup, I used a similar roll-around charger with a pair of GC batteries for a few years and it worked fine.