irony

[bigred]

Went to the Prevy today and of course as to be expected the batteries were down .I have a 100w Harbor Tool solar charger so I got it out run the wiring and got it hooked up to the batteries but the display would not come on .Got my tester out and found out that indeed the charger was putting out 12v DC While I was checking all this out ,I found an interesting sticker on the control unit which said 'In order for the read outs to function unit needs to be hooked to a fully charged 12VDC battery". Say what??Dear Harbor Tool, If I had a fully charged battery what in the h--- would I need with your solar charger??     And the saga continues!!!

[bobofthenorth]

I'll grant you that's an unusual requirement but a 100 watt solar panel is at best a joke.  Under ideal conditions - no shading, 90 degree incident light - it will give you something less than 10 amps of charge into a 12 volt bank.  In the real world it will trickle charge your battery(s) for a couple of hours each day.  So as long as there's no loads on them its all good, as long as they're charged to begin with.

[dtcerrato]

If 100 watts is a joke, what is a useful minimum. Just wondering...

[chessie4905]

So it's charging, but the readouts just don't work yet? Leave it hooked up and see how long till the readouts register. I would want one of theirs to be rated at at least 500 watts , especially since your batteries are low. Wonder how low they are. How many and what size? Any phantom drain will reduce effective current getting to batteries. Cold weather won't help either.

[bigred]

So it's charging, but the readouts just don't work yet? Leave it hooked up and see how long till the readouts register. I would want one of theirs to be rated at at least 500 watts , especially since your batteries are low. Wonder how low they are. How many and what size? Any phantom drain will reduce effective current getting to batteries. Cold weather won't help either.

I know that a 100w solar charger i a joke but to keep from pulling the battery's I thought I might get it charged enough to get the electronics to working on CC conversion's the house system is entwined with the chassis system .Even tho each one has a separate electrical system  ,you have to have a working house system to work all the electronics .If this solar deal doesn't work ,guess I will fire the gen set and let it run all day .Kinda of an overkill and I hate to do it .But I hate pulling the batteries even worse .Incidentally  .I have four agm house  battery's and four group 31 chassis battery's.

[Fred Mc]

As a starter system we put in 2 100 w panels and have 2 12v deep cycle batteries.We also converted all interior lights to leds.Last fall we spent 10 days boondocking without any trouble keeping the batteries charged up. To get a system to function to its max. proper wire sizing is critical.We plan to add a couple more panels and upgrade the batteries but we managed on what we had. I'm sure if you had one 100 w panel on constantly it would keep the batteries charged UNLESS you have a big drain.

[pabusnut]

I have an electronic Sears battery charger that is equally aggravating.  I don't know what the low point on it is, but I have tried to use it several times, and the code it displays basically says "you dumba**, this one will never charge!"

Then I get out my old one (Montgomery Wards I think), and it literally brings the dead back to life! It only has one switch(6 or 12 volts) and a gauge.  I think the battery makers are in collusion with the battery charger makers.

[bobofthenorth]

If 100 watts is a joke, what is a useful minimum. Just wondering...

I guess it depends what you want to do.  If you just want to float the batteries while the bus isn't being used then maybe 100 watts is (barely) adequate.  If you plan to actually use the power then anything less than 500 watts will be a huge disappointment.  In the OP's case I interpreted his comments as a desire to charge a depleted battery and in that circumstance 100 watts is a joke. 

[bobofthenorth]

  I know that a 100w solar charger i a joke but to keep from pulling the battery's I thought I might get it charged enough to get the electronics to working on CC conversion's the house system is entwined with the chassis system .Even tho each one has a separate electrical system  ,you have to have a working house system to work all the electronics .If this solar deal doesn't work ,guess I will fire the gen set and let it run all day .Kinda of an overkill and I hate to do it .But I hate pulling the batteries even worse .Incidentally  .I have four agm house  battery's and four group 31 chassis battery's.

My opinion/advice plus 5 bux will buy you coffee in most coffee shops.  IOW my advice is probably worth exactly zero but ...........

You should be really concerned about overly discharging either of the battery banks.  Even 50% discharge is going to seriously impact their lifespan and anything past that is flat out murder.  12 volts resting is pretty much equal to 50% discharged.  You can find tables that will tell you to go a little lower than that but really if you're concerned about the life of your batteries they should never see 12 volts resting voltage.  And don't think "once or twice" is OK - its not. 

[richard5933]

...CC conversion's the house system is entwined with the chassis system .Even tho each one has a separate electrical system...

Been there with the CC electric systems. They made fine conversions, but for some reason just did some weird things with their electrical work. On our 4106 I had to surgically separate the house system from the coach and generator systems. Wasn't easy. On our current bus they used the generator start battery as the house battery, and of course the two are intertwined.

I have 90% of the generator, chassis, and house systems separated now. The biggest problem is that CC used the bonded neutral/ground from the 120v system as the ground wire on some of the house 12v circuits. I think I've separated all that out.

With all that said, once you get your house system isolated from the chassis and/or generator controls you can add solar quite simply. My charge controller is wired to the house battery bank in parallel to the 120v battery charger. It has it's own set of lead, each with oversized battery cables to reduce any loss. We have three 180-watt ground deployed panels (so they can be in the sun while we're in the shade) and just one of these will provide more than enough current flow to be of benefit. While a 100-watt panel is not going to produce all that much on its own, it should be enough to keep a charged battery topped off and even allow a small amount of use.

The big secret to all this is how things are set up. We're using panels that produce almost 19 volts, and they are connected in series through a MPPT controller. This allows us to charge at over 14 volts with minimal sun. There are various ways to accomplish this and even a small 100-watt panel can be useful if connected through the right controller.

[Jim Blackwood]

You guys are great! I'm really learning a few things here. It helps a lot in the advanced planning stages, for instance my genset has it's own dedicated battery and I'm hearing that it probably makes sense to keep it that way. Thank you.

Jim

[Iceni John]

I'll never understand why solar panels are not standard on every RV and bus conversion!   Do people actually want to not keep their batteries fully charged while the bus is not being used?   I don't get it.   Spend a few hundred bucks on a few hundred watts of panels and a simple charge controller, then you'll always keep your batteries charged, for free, for ever.   What's not to like?   And on those rare days the sun doesn't shine at all, that's when you use the generator to bulk-charge the batteries back up to almost-full.

Obviously for extended off-grid boondocking you'll need more than a few hundred watts of power, but most people don't do that anyway.   If you have your house batteries (usually the much greater financial investment compared to the SLI batteries) charged by solar, then you can also charge the SLI batteries from the house batteries  -  I do exactly this by having an Ultra Trik-L-Start battery maintainer on each SLI battery, powered off my house batteries.   It's really nice to always see those little green lights on for each battery, knowing that they're always 100% charged and ready to go.

John

[chessie4905]

Solar works better if you have sunlight and lots of it. Here in Pa., Fewer sunny days; mostly cloudy is the norm most of the year.

[Melbo]

AND solar panels when parked inside don't make a lot of sense.  I just use an extension cord.  ;-)

Melbo

[bigred]

You guys are great! I'm really learning a few things here. It helps a lot in the advanced planning stages, for instance my genset has it's own dedicated battery and I'm hearing that it probably makes sense to keep it that way. Thank you.

Jim

By all means ,leave it that way ! Mine also has a separate battery .If the house system is down , it kills all the electronics ,ie you can't start the genset from inside or use the jump button BUT you can go to the generator compartment and start it from there!!!