I've been checking through the great threads in the truck camper university but have some specific questions relating to my exact set-up.
As many of you may recall I fitted 160w of Solar panels with associated charge controller to my camper. I also previously fitted a 140 litre compressor fridge after my previous fridge died. I also have a relay fitted to the truck so it charges the leisure battery when driving (which is usually every day).
After using the combination last week I now need to seriously think about my battery.
When I bought the camper in spring 2010 it came with a dead battery so as a quick fix I bought a budget 70AH leisure battery which I have been using ever since. Until I fitted solar in January this was mainly charged using a budget car battery charger which a previous owner had wired so it was charging whenever we had mains hook-up (which we do most of the time at camp grounds) - definitely not the thing to use to charge a leisure battery. Since fitting the solar I haven't used this in built charger on the basis that the solar should be keeping the battery topped up.
A couple of times this week we camped over night without hook-up and on each occasional I found that by bed time the battery voltage had dropped to the point where the fridge went into its battery protection mode by bed time. On the last occasion I turned the fridge off completely and then waited until 8AM when it was thankfully sunny and there was enough solar power to run the fridge again (at least proving the solar power is working).
I've yet to check the voltage of the battery - I'll have to check it tonight (it reads > 14v now, because of the solar) - so I guess I can then tell from the voltage whether the battery is still holding charge properly. Given the use of the car battery charger on it, and it being a budget battery which is sealed so I can't top up the electrolyte, I wouldn't be surprised if it is pretty dead now, so might need replacing. Unfortunately my little camper has only a small space for a battery - about 11.5" in length, and certainly not up to carrying 2 batteries. I could only fit a much larger one if I didn't take the portaloo with me - or possibly I could modify the area where the spare gas cylinder is kept to take a 2nd battery (about 3 foot away from the first one), but I would lose storage space.
Here to re-iterate are the facts:
* 160w (max theoretical) solar panels - permanently connected.
* 70AH battery - supposed to be able to use up to 60% of that (42AH).
* Fridge supposed to average 70w (just under 6 amps) = 6 hrs before reaching 40% charge of above battery.
* Charging from alternator too.
* Currently not charging when I do have hook-up
* Only room for 1 battery < 11.5" in length.
* I never use the converter - its output is electrically very noisy and the voltage is too high, so when we use 12v appliances in the camper we are running them directly off the battery even when we have hook-up - i.e. the hook-up only runs AC appliances and the fridge (which switches over to it automatically when it becomes available).
* As well as the fridge we normally run a couple of LED lights off the battery and occasionally the radio.
* As ever I don't want to spend a fortune on the solution.
So, after all this rambling - here are my questions:
1) I have no switch on my solar - it is charging the battery (via the charge controller) every day during daylight hours - Is this generally acceptable or will this in itself kill the battery? What is best practice here?
2) The battery appears to be sealed - would I be better with a replacement where I can top up the electrolyte?
3) Is it worth me fitting a 3-stage battery charger to use when I do have hook-up - to augment the charging from solar?
4) I do have a 3-stage charger at home, but I noticed that it isn't suitable for this application because as you turn on and off 12v appliances the voltage drop confuses the charger and after a while it assumes the battery is broken and shuts down. Are 3-stage chargers for RVs able to cope with this?
5) Will a 3-stage charger also cope with the competing voltage from the solar panels during daylight or will it similarly become confused and switch itself off?
6) Given the limitations above on size / space for only 1 battery - am I best looking at another wet battery or something like an AGM battery?
Thanks in advance - and sorry this was such a long question (in return I promise you all a trip report covering Prague shortly).
'07 Ford Ranger XLT Supercab diesel + '91 Shadow Cruiser - Sky Cruiser 1
'92 Suzuki Samurai 4x4 1.6
'09 Fiat Panda 1.2
'10 Citroen DS3 1.6 turbo
It sounds like you have a sealed lead acid battery; have you got a part number or battery label?
We went for AGMs because of the following:
-the flooded lead acid battery needed way too much attention (it definitely wasn't a cheap date!), and it died just a few years from it's birth;
-the flooded lead acid battery looses way too much charge sitting more than a month or 2 (as is often the case for us between expeditions);
-the flooded lead acid battery took way way too long to charge!
Replaced with 105 Ah AGMs, we have over 50 ah to use before recharging. The AGM can be recharged extremely quickly (they are affectionaly called: extremely fast recharge). I never have to woory about acid boil (cells drying out) or vast quantities of explosive gas (from potentially defective battery charger). Also, if you're driving long distances on bad roads (like across Africa), AGMs are extremely vibration tolerant, unlike flooded lead acid batteries (this alone precludes all but AGMs for us).
The only down side to AGMs is that they need a very specific charge profile, and you must check any charger you're contemplating for an AGM profile. And, AGMs are slightly larger and heavier (but not excessively so). Have a read here for more detail on AGM vs. flooded cell: von Wentzel on batteries
Your charging equipment is doing fine. You simply do not have enough battery capacity to do what you need to do. Is there an area outside of the camper, maybe in front of a wheel well or some area under the truck bed or in the engine compartment where you could add a another battery.
As the others have said, you need more battery. Is the 70AH battery you have a "deep cycle" battery? If not, you will kill it fairly quickly using it as such. And you need a lot more than 70AH to run a compressor fridge along with everything else. Find a way to fit two batteries somewhere, even if they are separate from each other (connect with heavy gauge wire to avoid excessive voltage drop). If you had 200+ AH you'd be a lot better off. Analyze your loads to determine exactly how much battery you need.
1. No, not if you have a good 3-stage controller. But I would definitely add an on/off switch (and a fuse if you don't already have one) to that solar circuit for safety's sake.
2. Not necessarily, but they are usually the best bang for the buck, assuming you keep the electrolyte level maintained.
3. Not necessary if you get adequate sunlight. Otherwise, yes.
4. Can't answer that one as I don't use one.
5. Same as #4.
6. AGM will eliminate the maintenance requirements as well as other advantages, but you will pay for it. If regular battery maintenance isn't a problem for you, and the other AGM advantages aren't needed, then flooded cells are more cost effective, IMO.
Gary and Zahra
93 Dodge Ram 250, 5.9L Cummins Turbo Diesel, 5-speed stick
87 SixPac 8' Truck Camper
94 Alpenlite 29RK DL 5th Wheel RV Solar 101
I'm with the AGM lovers for all the reasons listed. It would be nice to install two batteries for your solar panels. I think 160 watts is good for maintaining two batteries. Do you have space in the bed of your truck between the side wall of the truck bed and the camper wall. Several people have devised ways to move their batteries to this location or another creative location. That's the trick with a compressor fridge, it uses power. I am sticking with a propane fridge.
Good luck with it.
One problem is people grossly overestimate the ability of their solar systems. Just because it's daytime does not mean that the solar is putting out 160W. That is in full sun with the panels pointed directly at the sun at the ideal angle. On a flat roof you are only getting a fraction of the panel's capacity except at high noon during the summer solstice.
Right now your solar barely has enough output to power the fridge, let alone charge the battery from scratch, which it has to do every morning.
I agree with the others, you need more battery capacity somehow.
In addition, you will either need more solar to keep up with the charging demands and/or an alternative means of charging the battery(ies).
What does the charge circuit you currently use to charge the camper battery from the truck alternator look like?
I have less solar, 135watt, but have 2 group 29s so have about 200+AH. at 11 1/2" limited to group 24-agree 'theres the problem". If you did go true AGM you can stack on thier side which might allow fit?. Looking at your battery pic looks like water tank? might interfere. Plus Im unsure if your solar controller is up to the task of AGMs though. But however you can manage you need more battery. Id also kick down the refer at night.
a SEALED lead/acid battery or 'maintenace free' they use to be called, Ive replaced more than one cause it was dry-I wouldnt buy again.
My opinion to your questions
1. Good controller will not kill battery-worse is letting them discharge/unmaintained. As noted a master kill switch is a good idea.
3. Absoluetly yes, if you have power your charging batts (regardless of weather, time of day) have ample supply for everthing else 12v & 110v.
4. Yes-different animals
5. Yes to first question, no to second.
6. Well I have opinions on battery types but IF only 1 battery Id get what ever has highest ah or reserve capacity (which is going to be a small range). Though your current battery probably isnt delivering its original design output-new one isnt going to do much better at least for very long. You really need more battery.
...The only down side to AGMs is that they need a very specific charge profile, and you must check any charger you're contemplating for an AGM profile...
The AGMs sound interesting. Are there any problems charging them off the truck alternator?
Is the 70AH battery you have a "deep cycle" battery?
It is marked as a leisure battery as opposed to a starting battery. So I think it is a sort of deep cycle battery, but I read somewhere that these marked as 'leisure' are part way between a full deep cycle battery and a normal battery.
...What does the charge circuit you currently use to charge the camper battery from the truck alternator look like?
There is just a wire from the truck alternator that goes through a relay (switches on 30 seconds after the truck is started). When I had it fitted I checked and could see the battery voltage increasing. I might check it tonight (when it is dark and the solar is no longer working) and verify what voltage it reaches and that it is still working - I did catch the electrical sockets on the ground during some off-roading recently, maybe I damaged that particular socket.