Panda (Classic) John Dragon Man's 4x4 Sisley

Good to hear you have the driving bug again John, keep us updated - I am interested to hear how you get on with the alternator too as I would like to do similar in order to run a couple more spot lights

yeah i know what you mean. i want it to do the same and run (what is left of) my radio gear

the battery in the back never does fully charge and now i think it has broke it a bit. its a shame cos good 100Ahr batteries dont come up very often. i really need to make a desulfator maybe that will get it living again.

the front battery does not hold a very good charge :/

Have you tried just running a single larger battery from a diesel-engined vehicle rather than a pair of batteries? How have you managed to split the feed to and from the rear battery or do you just connect it up basically when you need to use it?

That's also the problem with batteries if they don't get fully charged then emptied or have a regular pull off them they tend to "forget" their capacity - tis a bummer

All working...

Twin batteries and altinator. I have this set up with the batts in parallel. Was going to up my alt to 120amps. But having read a bit I'm not sure I need to...is it not true that an alt sticks out the same charging voltage no matter the size and the only reason to up the rate is if your running aircon, lights, radio, etc all at the same time as in big new cars??

I have just bought an 80w solar panel to run to both batteries via a controller. I will have to wire the batteries separate from each other or the panel will only see them as one if wired in parallel. My question is if I leave them in parallel and disconnect one of the batteries -ve to the cars chassis will the controller still think its one battery?? Sorry if it's a bit off topic but thought you may know...well it's not too off topic as you love this kind of thing...

the battery to the controller will only put charge into the battery with both leads going to it. so it will only see that one.

i built a charge controller ages ago when i had the diesel corsa. (the one i never got on the road due to silly over priced insurance).
back then it was a simple thing that could be set so that it only pushes charge into the battery when the engine is running but can be selected so if the front or back battery is completely flat i can switch what battery i'd want to pull power from and/or charge to.
since then i modded it considerably adding microchips and bits from other chargers.

when the ignition was off the 2 batteries will be isolated from each other. when the ignition was on it was in standby mode. standby mode was.. if battery voltage in one of the batteries was under 10.8 volts and the other battery was higher volts it would automaticaly switch over to the battery with the most voltage (charge) to start the engine. if both batteries read the same voltage it would key in both batteries to start the engine. if battery voltage on both battries were very low it would beep and only key in both battries as soon as the starter solenoid wire became live so both batteries would not be trying to take charge from each other. another thing i added was that when starting from low batteries it would do a total black out mode where it would turn off everything electrical (dash, fuel sender, lights, alarm, wipers, fan, radio, radiator fan, even the charge controller its self) so absolute 100% power was going to the starter motor from one or both of the flat batteries. i even went thurther to run all of the engines electronics from the other battery (even though it was low too) so the voltage drop of having the starter motor on it would not effect the spark. it would cycle through getting the engine spinning on both batteries, then switch one over to run just engine electronics. given the batteries had enough juice to just get the engine over compression twice it would fire up.. not bad for a carbed engine.

when it detected the engine was running (with a little voltage sniffer circuit i built to read +14 volts as 14.4v is about standard alternator voltage) it would go into "charge" mode where it detects which battery has the least voltage then charge that one first. if the voltage of both batteries was within a tolerance of about 10% it would charge both batteries up together.

most of this was made from old chargers i spliced together i found at different scrap yards.
the relay system was a pain to make. on normal "ignition on" it puts everything through a 150 amp rated relay. not enough for starting the engine. for that i had to wire in a separate starter solenoid which could take the amps but only power up (from a battery of the controllers choice) when and only when the key was turned to the start position.

one of the things i want to add to this is a desulfate function, where it automatically disconnects the battery of choice from anything in the car then nukes the battery with about 15 volts for about 20 mins to half an hour (using a DC to DC voltage booster). this would be a manually activated option

sadly if both batteries were really flat and it was a rainy dark night, the batteries would never fully charge due to the alternator amps not being high enough. (it would charge them both eventually but would take ages)


this is the kind of things that i build when i am bored.

lately i have playing with tesla coils.. no.. really..

I understood all that!! Seriously, that sounds impressive..

I don't need to go that far, but what I want to be able to do is have the solar panel charging the batts when I park up and have the alt charging when driving.

The controller I have is capable of seeing the alt is throwing in more charge and will just sit there. It also has two separate connections for each batt and I can choose what percentage goes to each batt (80/20 50/50 etc) I understand that I need to have the batts wired separately of each other to avoid the controller thinking its one big batt.

At the moment things are as follows...

Batt one (leisure batt) the alt goes to this, then from the v+ to the v+ on the batt two (starter batt) so how can I get what I want?? Simple ideas with simple diagrams for a simple chap would be great...

so you want both batteries isolated from each other.. but because of the car's wiring they are linked in parallel constantly?

sounds like if you were to make a relay that sits in-between both battery lives that can be manually turned on (or comes on with the ignition on a 3 way switch), then a large starter solenoid that only comes live when the key is turned to engine start that would sort it...
both batteries would become isolated when the ignition was off or when you chose to turn it off.

that is how my first charge controller worked. only i added some amp meters so i could monitor how much power was going where.

Bloody techies.......
I'm confused.
Why do you need so many batteries?
Diddly Pom Dave

pandamaniac said:

Bloody techies.......
I'm confused.
Why do you need so many batteries?
Diddly Pom Dave

Click to expand...

To run his Disco tech

Most Easterly Pandas said:

To run his Disco tech

John's Magical Disco Panda - YouTube

Click to expand...

Love that car man!

Dragon Man said:

lately i have playing with tesla coils.. no.. really.

Click to expand...

Tech time...

I was aiming to keep things mechanical rather than electronic as I want to minimise the problems when I'm away.

I already have both batts with an isolating wheel on both the negative terminals. What if I added an Anderson plug to the positive cable between the batts. So, I would run the alt cable to the starter batt and tee off to the leisure batt with the Anderson when driving. When parked up disconnect the negative via the wheel...unplug the anderson...then the solar panel would see two separate batts and charge accordingly.??

Sounds like you just need a split charge relay. It charges both batteries when the engine is running and then isolates them when stopped so the main vehicle battery doesn't go flat whilst you're running stuff from the leisure battery.

Connect the solar charger to the leisure battery and it will charge both when the engine is running (although I guess it might not charge if it sees 14 volts from the alt) and only the leisure battery when stopped.

http://www.marcleleisure.co.uk/Sund001/SplitCharge01.htm

An isolator switch or an anderson plug on the positve cable between the batteries would do the same job, but the basic system in the link is no more complex than the other relays in the car.

if you want to keep thing... "manual" then that system would wok.. much more fun to make it automatic though >_<

Thanks for that guys....

Last question, because the batts share a common earth ( the chassis ) would this be a problem? Or just disconnect the earth from the leisure batt when charging from the solar panel?

nahh i cant see why it would be. all switching would be done (in the charger) by the + line.

do you know if it is PWM charger? even then it should be ok.

This is the product...

http://www.ebay.co.uk/itm/110877737967?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649

The controller has PWM technology. I have a split charge relay, but was looking for ways around using it. I may decide to use it now. Thanks again.

hmm. the way i would do it if it was me..
i would stick hefty relays/contractors on both "car" leads going to the battery, on both batteries. stick the charger on the batteries so they do not go through the relays. then setup a small switch in the car that you can flick on which would then turn all relays on so the ignition can be turned on and engine can be started.

that way both batteries will be isolated and charge only with the solar charger when you are away from the vehicle. but as soon as you are in and driving around both battries will be being charged via the alternator.

its real simple.. the hardest bit would be finding the really heavy duty relays.

saves all the manual bonnet lifting and turning batteries off


all this talk on batteries reminds me, i really should stick my dads car on charge. its only a few months old but having it stand around cant be doing it any good.

the bank loan has been paid off on it (thanks granddad) and it is going to become my brothers new car. just waiting for the V5 to come through.

A Ctek D250S dual will do the job very well being a DC to DC charger with solar panel inputs. There is a vid on you tube, but jeez it's not cheap...

agreed.. anything contaning the words "free energy", "wind power", or "solar" and the prices go whhheeeeeyyyyy high.
yet in reality £15 worth of electronic components go into it and about £5 for anything else. solar panels can be made scary cheap, but greed makes the world go around and were still here burning high carbon fuels... with massive taxes.