Is 100w sufficient?

rf9ridrer

rf9ridrer

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2007 ACE FIRENZE
Following on from my post about charging the vehicle battery, another question!
I have a 100W solar panel connected to a single leisure battery which works fine, but there is room on the charger panel to connect another set of wires for the vehicle battery.
Is 100w sufficient enough to charge both batteries?
 
Do you mean the solar controller? If that is the case you can usually set the controller to charge the leisure battery ,say 90% of the solar charge and the 2 nd battery( starter) 10%. Once the leisure battery has reached a full charge it will all switch 100% to the starter battery untill that is then fully charged. (y)
 
100W should be fine. The starter battery only needs a trickle charge to top it up as the alternator does most of the work. I have just replaced my OEM starter battery at 16 years old. It's lasted that long I think because of the 120W solar panel providing a couple of amps when required.
 
Current and previous vans had just that and it works just fine for me. All depends on what demands you put on the batteries. Mhy needs are fairly low.
 
rf9ridrer said:
Following on from my post about charging the vehicle battery, another question!
I have a 100W solar panel connected to a single leisure battery which works fine, but there is room on the charger panel to connect another set of wires for the vehicle battery.
Is 100w sufficient enough to charge both batteries?
Click to expand...
Is it a dual battery solar controller?
You will need to take two cable to the starter battery.
The 100w panel will be enough to keep both batteries fully charged as long as you don't ask to much of them.

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Ok, thanks all, its a Vechline LM series solar power intelligent PV controller, trouble is the user manual is tiny, and i cant even read it with a magnifying glass!
Looking online for a readable version! :LOL:
 
It seems its not a dual controller, the 2 spare connections say "load" on them.
Guess ill be looking for another controller.
 
After fitting a 100w solar panel and controller I have never had to use ECU when the MH is parked on my drive. The panel keeps both batteries topped up both summer and winter and my OEM battery is now almost 12 years old and still going strong. I've not had to replace the Leisure battery (original one failed) since fitting panel. Best modification to the MH I ever made!
 
DiggerJon said:
After fitting a 100w solar panel and controller I have never had to use ECU when the MH is parked on my drive. The panel keeps both batteries topped up both summer and winter and my OEM battery is now almost 12 years old and still going strong. I've not had to replace the Leisure battery (original one failed) since fitting panel. Best modification to the MH I ever made!
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You’re lucky. 100W certainly keeps both batteries topped up in the summer months, but I found in the winter I needed to turn on the EHU a couple of times as voltages were dropping. But we do have large trees to the east of our drive so amount of light is reduced. For the same reason we found our house wasn’t suitable or economic to have solar panels on the roof.
 
does anyone know if i can fit a small solar panel and cheap controller straight onto the engine battery without it becoming over charged
 
A 100W panel is fine in the summer but will do almost nothing on dark winter days.
 
chrisandbev said:
does anyone know if i can fit a small solar panel and cheap controller straight onto the engine battery without it becoming over charged
Click to expand...
Yes - any cheapo PWM controller will do and it will ensure battery isn't over charged.

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We find a 100w panel ok most of the year to maintain both batteries. I am shortly adding another panel though.
 
chrisandbev said:
does anyone know if i can fit a small solar panel and cheap controller straight onto the engine battery without it becoming over charged
Click to expand...
You can buy panels with a controller built in for that specific purpose. Something around 10W-20W will be enough, assuming you're not powering an alarm. Google "solar battery maintainer".
 
I'm surprised no member has advised you to work out what your power consumption is before arriving at an answer to your question. I would advise that you can never have enough solar power and if your going to install S.P get as much up there as you can. In the UK 100 W is going to be inadequate in the winter and may not even be enough in the summer depending on how you use your battery bank. Many FLT's will double up on their leisure batteries and get loads of S.P. up so they can wild for extended periods. If your going to be on Hook up all the time, you can probably get away without any Solar. I'm sure you will work out what your needs are and adapt accordingly.
As for charging both batteries, I would recommend getting a decent MPPT solar controller that is capable of charging both sets of batteries and is adjustable with respect to how much charge can be split between the battery banks, again you will find out over time what this split should be for your usage. This means even less charge going to your habitation battery bank and will be pretty much useless in the winter in the UK.
 
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As a rule of thumb I always suggest that you need a minimum of 100w of solar for each 100a/h of battery it will charge. More is of course better. North of the equator we do not get full sun for very long each day, even less the further north you go and of course the time of year, So the maximum wattage is rarely achieved for very long each day
 
Thornebt said:
A 100W panel is fine in the summer but will do almost nothing on dark winter days.
Click to expand...
Our 100w panel keeps the 100ah leisure battery and 85ah starter fully charged all year round.

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DBK said:
You can buy panels with a controller built in for that specific purpose. Something around 10W-20W will be enough, assuming you're not powering an alarm. Google "solar battery maintainer"
Click to expand...
A 20W SP would provide only 1.34 Amps under ideal conditions and only while there is sunlight. Previous threads on these type of battery maintainers suggest there pretty much useless, especially when placed behind a windscreen and not kept in alaigment when the sun arcs across the sky. I would imagine in the UK they would be useless, I.M.O.
 
Depends what the quiescent drain is. Our car had a 5w monocrystoline panel in the window during lockdown, angled south it made about 125ma in sunshine behind the windscreen. On a run of sunny days the voltage was edging up to over 15v 😳.

Problem is if you fit a controller on a tiny panel, in winter on dull days the controller can use more power than the panel makes 🙄 so they can be quite useless.

On a motorhome the ideal solution is EHU with a low current maintainer. Next best is a big panel on the roof with starter battery maintenance facility. The reason I say next best is that the controller will cycle the leisure battery up to 14 odd volts every day which is unnecessary.
 
If you do get around to wiring to your starter battery just make sure you use suitably sized cables and make sure it has an in line fuse, again suitably rated for the job.
 
If you do get around to wiring to your starter battery just make sure you use suitably sized cables and make sure it has an in line fuse, again suitably rated for the job
 
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Peter and Julie said:
Just bought this for battery (starter) only. Not tried yet as bus is in France.

10W 12V Solar Panel Trickle Charger Battery Maintainer Kit Monocrystalline with 10A Solar Charge Controller for RV Marine Boat Off Grid System
Click to expand...
I liked the statement about the solar charger controller preventing the battery from being overcharged. A 10W solar panel will only provide 1.2 Amps if it can meet its maximum output, which is not going to happen. I.M.O. a piece of useless junk.
 
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