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Almot

out there

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Posted: 05/12/19 01:32pm Link  |  Quote  |  Print  |  Notify Moderator

BFL13 wrote:

So it is ok to do several 50-90s in a row with AGMs, then go home and recharge to full (.5a/100AH) at the specified 14.x level for that model AGM, and then go to float voltage until the next trip?

No need for a 20% recharge in that case?

Dangerous to interpret when noise to signal ratio is high, isn't it...

I don't think this is ok. Better not to run 50-90 for prolonged time. Especially if solar is all you have.
Scenario: 300AH bank on 490W solar is 80-85% before sunrise, goes into Float around noon when current drops to preset value (AGM at 95-96% at this point?), and then stays in Float for 6-8 hours. Sort of a standby service. Generator-shmackerator...

Itinerant1

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Posted: 05/12/19 01:40pm Link  |  Quote  |  Print  |  Notify Moderator

MEXICOWANDERER wrote:


Perhaps the hoopla surrounding lithium batteries is true to some extent. But I refuse to believe lithium if goof-proof.


Goof-proof no, maybe more forgiving possibly.

Being a slave to a battery gets old only time will tell for lfp.




BFL13

Victoria, BC

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Posted: 05/12/19 01:43pm Link  |  Quote  |  Print  |  Notify Moderator

Dropping to Float at 96% means not getting down to .5a/100AH at 14.4v, so you are undercharging. Must go to proper full every so often, however you can arrange to do that.

One way is to split the bank so you can fill up the disconnected batts while the others do the work, then swap and do a proper fill of the others.


1. 1991 Oakland 28DB Class C
on Ford E350-460-7.5 Gas EFI
See Profile for House electronics set-up.
2. 1991 Bighorn 9.5ft Truck Camper on 2003 Chev 2500HD 6.0 Gas

Almot

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Posted: 05/12/19 02:45pm Link  |  Quote  |  Print  |  Notify Moderator

BFL13 wrote:

Dropping to Float at 96% means not getting down to .5a/100AH at 14.4v, so you are undercharging. Must go to proper full every so often, however you can arrange to do that.

One way is to split the bank

300AH bank. Controller is set to terminate the Absorption at 1.5A or in 2 hours, whichever comes sooner. In the middle of the day very often there are no loads, except 0.8A fridge draw when it's cycling, so 1.5A is what I see. Must be more than 96% then. I don't use a battery monitor, couldn't justify the cost or need.

Could do bank-splitting, yes.

BFL13

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Posted: 05/12/19 03:30pm Link  |  Quote  |  Print  |  Notify Moderator

You want the 1.5a (at most)/100AH at Vabs, so having the 2 hr option whichever comes sooner would be wrong for sure. With Wets you can do the 2 hr if you think going longer will cause water loss.

Also that 1.5 if seen on the controller is not the same as amps to the battery, which could be less if some of those amps showing on the controller are going to load. (which you have to guess at with no battery amps monitor).

Going under the .5/100 does not mean overdoing it. (When amps to battery start to climb back up it does mean that) My 250AH AGM gets down to 0.6 amps at Vabs for its Full if I leave it to do that. ISTR LY sees his AGM's low amps number get higher when he has not gone to a true full for a while. After he gooses it, that full amps number goes back down.

pnichols

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Posted: 05/12/19 04:47pm Link  |  Quote  |  Print  |  Notify Moderator

BFL13 wrote:

MEXICOWANDERER wrote:

Or go to Harbor Freight and buy their 2 cycle 800 watt generator

Then buy a MEGAWATT-400 watt power supply. Set it for 14.4 volts

When the sun goes down, the Megawatt comes online and runs until it out of gas.

If the batteries are real low this combo will stuff around 400 amp hours into the bank. If used and the batteries are sucking less than bulk maximum the generator will run longer before conking out.

This will zot a lot of amp hours into the batteries for less than 200 dollars after the sun goes down.


I can't believe Mex is recommending one of those horrible little things as a useful generator.

I posted a couple years back on my adventures with a King 951w which is like an HF model 2-stroke. It was impossible for me.

Tug on the starting cord and it pulled the gen over on its side. Put your foot on the top and pull and you go flying and so does the gen. After much toil, you do get it started (using lots of ether starter spray-"not included")

Clouds of smoke for a while until it settles to just a little smoke. Ok now try to run a battery charger. The 951w would just barely run a 35 amper, but was happier with a 20 amper. Whoopie-doo!

I hated that thing. Gave it away (with a can of mixed gas, even) to an unsuspecting guy who thought it would be just perfect! Tee hee.


BFL ... the RV battery charging anywhere anytime anyweather method that Mex is recommending above is outstanding with one small equipment adjustment ... replace his recommended generator with a used version of this instead:
http://www.honda-ex650.co.uk/about.html

Super quiet (54 dbA all the time), four-stroke, starts right up on the first pull with old straight or drunk regular gas, steel case instead of plastic, but alas ... has to still be kept chained up because from a distance it still looks like a late vintage red Honda. [emoticon]


Phil, 2005 E450 Itasca Spirit 24V

MEXICOWANDERER

las peƱas, michoacan, mexico

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Posted: 05/12/19 04:47pm Link  |  Quote  |  Print  |  Notify Moderator

However you want to split it the rule about not leaving AGM batteries undercharged can not be violated without consequences. The deeper the OVER discharge the more often the battery must be 100% charged. The MORE the 20% of capacity rule applies.

So what is worse. Leaving a battery at 95% capacity for a year?

Or

50% full for six months?

Battery management? I sip a hot cup of Chiapas coffee and enter the gen shed. Batteries are at 24.2

I press the starter button and twirl the timer for 3.5 hours.

210 minutes later the generator disconnects from load. H-Rummmmm. I wander uphill and turn the key off. Five minutes later the gen shuts off. I return to a glass of mineral water and pick up my e-Book. Captain Snotrag is about to be jettisoned through the airlock.

The physical effort of it all is becoming unbearable. A person should't have to go through all that to maintain a measely 3,300 amp hours of flooded batteries. BTW charging amperage at shutdown was 13.88 so next time maybe another 20 minutes or so?

AGM would be easier. Just look at the ammeter. Sixteen? Fully charged? CLICK

20% of 3300 is 660. The big charger + the lombardini + the small charger + 120 amps from the 4024 Trace total is more than a thousand amps. But 70 100 watt panels + say 100' of 250 mcm cable would be a tad costly. And a few hundred feet of No 2, 4, 6. and 8 interconnects are not cheap.

It's all a matter of perspective -- not assumption.

Demanding that power be 100% solar reminds me of cruising sailboat skipper who demand every inch of the voyage be done under sail. Neh what's arriving a week later than everybody else? Oh wait, they're all gone and are halfway to the next port.

Back when I horse packed I noted purists walked with a sixty pound pack and ate dehydrated hog glop. Could smell them coming. Thirteen days without bathing because of forty four degree stream and lake temps. Whatever turns ya on.

BFL13

Victoria, BC

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Posted: 05/12/19 05:53pm Link  |  Quote  |  Print  |  Notify Moderator

Phil, just happens there is one for sale locally here. $350 Can is about $262 US.

However, I paid only about 200 more for my new B&S P2200 (1700 cont) gen (on sale), and it can run my 75 amp charger. So no thanks. [emoticon]

https://www.usedvictoria.com/classified-........-EM650-Generator-recent-service_33336540

Almot

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Posted: 05/12/19 06:42pm Link  |  Quote  |  Print  |  Notify Moderator

My 0.5A/100AH or 2 hours timer is what it is set to. Timer can be set to any value from 1 to 240 minutes. I wonder how many people choose to keep AGM at V Abs for more than 180 minutes.

When it reads 1.5A on controller at V Abs before switching to V Float, it is 1.5A to battery. If fridge is cycling at that moment, the current is +2A, timer takes the authority and terminates Abs in due time or the fridge shuts down and control reverts to current. Alright, not 1.5A to battery - 1.52A counting the propane detector. I know my system, know what loads are on, there are no gremlins or people to do something without me knowing.

I wish my AGM could drop below 0.4A/100AH, but it doesn't do this anymore. What Mex said about AGM being either bad or tolerable is correct, a horrible Chinese cr-ap is what I have.

* This post was edited 05/12/19 06:59pm by Almot *

BFL13

Victoria, BC

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Posted: 05/12/19 07:00pm Link  |  Quote  |  Print  |  Notify Moderator

Almot the whole idea is to leave it as long as it takes to get down to the .5/100. It makes no sense to throw in an option to cut that short in case it takes longer than two hours. (With my 250 AH batt, it takes many hours to get that far down, dragging out the time as amps get lower as you know.)

It would take a long day of sunshine starting with the battery already up quite a bit and no load, to get that far along.

If it is not convenient to change the routine, then you just have to get new batteries sooner rather than later. How much sooner and whether that matters any, is up to the individual RVer--which is exactly as it should be.

* This post was edited 05/12/19 07:07pm by BFL13 *

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