Question 1 If a van is running Solar Panels and has a dedicated Solar Panel regulator. Can you still hook up an automatic switch to charge from the alternator and connect a 240v charger for when hooked up to a powered site! What would be involved!
I know you can get "all in one" devices that will control all 3 situations in harmony but the cost is quite high.
Question 2 With house battery's inside the van, I understand if they are wet cell battery's you have to vent them to the outside. Whats involved with that! Can you just build a plywood box around the battery's that seals up and put a vent to the outside at the top!
Does the box even need to be sealed tight or could I just vent the bottom of a cupboard and put them in there!
Any help on these would be greatly appreciated!
crzyhrse,
Dec 13, 12:20am
1) I would just leave both the alternator and solar charger hooked up permanently. They both have similar voltage outputs so no harm will be done - the battery only draws what it needs and the solar panel regulator will limit what it can supply current wise. Same goes for mains charging.
2) They only need to be vented because of charging in an enclosed space and hydrogen build up the process of charging. I would vent the top and the side of the enclosed space to atmosphere.
tmenz,
Dec 13, 12:39am
1) You will need to ensure that the 3 charging systems can't feed back into each other. This can be done with diode isolators which are readily available. The 'float' voltages from the solar panel regulator and mains charger may need to be tweaked up slightly to allow for the voltage drop in the diodes. (approx 0.2~0.6v depending on the type of diodes used). Some solar regulators and mains chargers may have diode isolation/protection built in and may not need external diodes added, but the car system will have to, to avoid having the caravan battery trying to power the vehicle systems when the alternator is not running. Note that because of the voltage drop across the diode, the alternator will never be able to charge the caravan battery to it's full float voltage. (Unless another diode is added into the feed to the vehicle battery to equalize the voltages - this diode would have to carry the full vehicle systems current - these exist but are fairly expensive). 2) Yes, you will definitely need to vent the battery box. Even with a 'sealed' battery such as an SLA or 'maintenance-free' type, there is always a possibility of buildup of hydrogen and oxygen in a very explosive mixture if batteries are overcharged at all. Allow venting at the top because both gases are lighter than air, and some venting below the top of the battery to get a through draught.
petermcg,
Dec 13, 12:41am
Presume you have starting battery and house battery!My one is just vented from below, and I think works well. Do you charge house battery from the engine alternator while driving!
crzyhrse,
Dec 13, 12:44am
The ignition switch does that.
bigfatmat1,
Dec 13, 1:10am
connect the 2 batteries through a voltage sensitive relay connect solar reg and smart charger directly to house batt. if you use a dual sense vsr vehicle batt will charge when on 240
tmenz,
Dec 13, 1:19am
Only some of it!
thejazzpianoma,
Dec 13, 1:44am
Wow thanks guys! That was a great eye opener about the Diodes I had not considered the voltage drop using those.
I am liking the voltage sensitive relay idea, good to know what you officially call them too! (note my scientific "automatic switch" in the description!)
Great to know I can just use common sense with regard to venting the battery enclosure. I wasn't sure if there was some kind of crazy regulation that covers it whereby you had to build the battery enclosure out of a certain kind of material, the vents to be a certain size etc.
Many thanks people, you rock! I will come back with more questions as I get stuck.
thejazzpianoma,
Dec 13, 1:48am
Wait! I have another couple of questions already!
O.K so according to my math I reckoned a couple of 6v 220ah deep cycle battery's wired in series would be the go.
Can I just treat these as one 12v battery with regard to charging etc!
Also. I like the look of the 12v microwave ovens but would the occasional peak draw of 900w be too much for a couple of those battery's when the oven is on!
Thanks again.
bigfatmat1,
Dec 13, 2:26am
yep charge them as normal but your smart charger what want to be at least 25amp
thejazzpianoma,
Dec 13, 2:39am
Sweet!
tmenz,
Dec 13, 3:50am
Just make sure that the 2 batteries are same make, model, age and condition - otherwise the charge voltage may not be shared equally, leading to overcharge on one and undercharge on the other and eventually premature failure of both.
2 x 6v 220ah batteries gives you 2640 watt hours max - this should be enough to power a 900 watt microwave for short periods. Deep cycle batteries can handle high currents OK. It's 75 amps so you'll need really heavy cabling! Best to 'try before you buy' if you can. The microwave suppliers should be able to give battery capacity recommendations.
Thanks for that! Don't worry the microwave will be just above the battery's and I was planning on some serious cables! I am actually using a voltage drop calculator to be extra fussy and make sure everything is spec'd correctly in that department. Both battery's are identical and will be brand new so no worries there either. but good to check as I could easily miss stuff like that.
Good to know the short periods of high load are O.K, I have limited time on this project and there is a lot of stuff where I have just enough knowledge to be dangerous!. Hence the questions!
Wouldn't be so bad if I had a lot of time to research but I think its shaping up alright.
Thanks again for your help!
thejazzpianoma,
Dec 13, 4:23am
This is Gold! (especially the 12v shop link, and the bit about some microwaves just having an inverter built in)
solarboy,
Dec 13, 6:39am
Is the 900 watts the cooking power ( as often appearing in large figures on the appliance front/door )or the actual power it uses ( see the wee label on the back with hertz and voltage too )!The power used is normally around 50% higher than the "cooking " power.so needs to be allowed for with inverter and battery capacity.
solarboy,
Dec 13, 6:40am
I presume the van IS a Fiat Multipla !
pup2,
Dec 13, 12:51pm
Hey Jazz, one thing to note. We have found solar panels tend to cause the battery to use water (house batteries). Best to set your batteries up so you can top them up as required without to much hassle. We also use voltage sensitive relays when setting up the type of system you are after. Same as Matt mentioned
tmenz,
Dec 13, 1:21pm
Yes, it's very important to have a good regulator between the solar panel and the battery to ensure the float voltage is correct and there is no overcharging that cause water loss.
thejazzpianoma,
Dec 13, 1:42pm
Good thinking but I was on to that one that one.The actual consumption on the one I was looking at was only 750w but I was allowing 900w as a peak draw in case of other things running at the same time.
I know that is a low figure but the 12v microwaves are quite small and possibly more efficient.
Thanks for the thought!
thejazzpianoma,
Dec 13, 1:46pm
No, Fiat Ducato. you can get Multipla campers though. very nice they are too! The Ducato is just the wee 2.3 but it fair flys! http://www.youtube.com/watch!v=67Rvn38lACM
thejazzpianoma,
Dec 13, 1:48pm
Good to know! I will change the battery situation to suit, might go for under the seat rather than bottom of the cupboard for better top access. Great info thanks!
tmenz,
Dec 13, 1:50pm
Note also that a battery's Ah capacity rating is usually calculated as a 20 hour rating. For a 220 Ah battery this means that it will supply 11 Amps for 20 hours. If the current draw is higher then the capacity has to be derated. For a draw of 7 times the 20 hour draw, it may be as low as 50% - i.e. 110 Ah, giving a MAX time of an hour and a half rather than the expected 3 hours. Have a look here for some info: http://homepages.which.net/~paul.hills/Batteries/BatteriesBody.html
thejazzpianoma,
Dec 13, 2:01pm
I was going to give one of these a shot. Price is cheap but if it does what it says it does should be a nice unit.
Here's a silly question for you, with the likes of these where they monitor the discharge for you. I take it you have to route the main feed through them in series like you would an ammeter!
Now with my microwave and a few other bits together drawing say up to 85 amps I wonder it it will cope!
I suppose I could bypass the microwave like you do a starter motor when wiring an ammeter if need be.
thejazzpianoma,
Dec 13, 2:07pm
Someone mentioned this yesterday, yes very good thinking. I am O.K though (I think) as the 220a/h leaves me with about 30% redundancy even when calculating to only run the battery's down to 50% in miserable winter conditions. Plus the microwave will only go for a maximum of about 10 minutes a day.
I will read your link though to be sure!
thejazzpianoma,
Dec 13, 2:11pm
Great link tmenz!
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