longy509
Member
Cheers Tony i think the battery might be screwed i gave it an overnight charge it seems o sit around 12.2volts now, can anyone tell me if it is normal for the main battery to stay over 14volts
Dual battery setup
- Thread starter Laith
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Cheers Tony i think the battery might be screwed i gave it an overnight charge it seems o sit around 12.2volts now, can anyone tell me if it is normal for the main battery to stay over 14volts
bods
Member
I have a turbo timer which shows volts when the motor is running on my d22. On a cold start (first start of the day usually) I get around 14.3v. A hot start will usually sit around 14.1 at idle, down to 13.8-13.9 when the car has been running for a while and the batteries have a bit of charge in them. I have a basic projecta vsr100 ( just a solenoid type isolator)
12.2V is way, way too low. A full battery should have 12.6V or higher (2.1V per cell, 6 cells = 12.6V). 12.2V is about 60% charge and if that's fully charged and rested for half an hour before measuring, I'd suggest there's probably some sulphation in the battery or the plates have deteriorated beyond the point of usability. I definitely wouldn't rely on that battery for running my fridge!
Yes, it's absolutely normal for the starter to hold a higher voltage once the alternator starts feeding it. 14.4 to 14.7V is the ideal charging range for a starter battery. Once the engine is turned off (and the ignition turned off) the battery should fall to around 13V fairly quickly and over the next hour it should drop to 12.6-12.8V.
longy509
Member
just went and bought a new fullriver 120a/h agm today hopefully it fixes me up bloody things arnt cheap at $330
Mgmd40 are you referring to the position of the starter battery in the engine bay?
The ONLY battery I'd consider for there is an Optima spiral-wound AGM, which can also be used as a cranker. The FullRiver AGM will probably be destroyed if you tried drawing the 500+ amps to turn over the diesel engine.
The ONLY battery I'd consider for there is an Optima spiral-wound AGM, which can also be used as a cranker. The FullRiver AGM will probably be destroyed if you tried drawing the 500+ amps to turn over the diesel engine.
Nomadic Navara
Member
This is a problem with charging auxiliary batteries from an alternator. The alternators in most vehicles up to the very recent ones have temperature compensation in them. This is there to stop batteries from being overcharged. As a battery warms up (and they all do when accommodated in an engine compartment) they require less voltage to charge them. If the alternator voltage is not reduced as things heat up the voltage would be too high for the battery and would thus boil it dry.
Many people dabbling in battery systems think an alternator monitors the charge level in the starter batteries. They don't. They just measure their own output voltage (and thus the terminal voltage of the battery if there is minimal voltage drop in the cable between the alternator and the battery.) To measure the charge level of a battery you need current shunts in the circuit to measure the charge current at known charge voltage. Motor vehicles do not have this extra circuitry.
I suspect that no one (or very few) have their auxiliary battery under the bonnet where it will warm up like the starting battery is. That poses a problem for charging auxiliary batteries. Your alternator is running at an output voltage level to charge a hot battery. Your auxiliary battery is sitting down the back, still cold and needing a higher voltage to charge it.
If you only use your battery for a couple of days at a time for running a fridge then the alternator will keep the battery charge high enough to stop it sulphating. It probably will rarely charge it to full charge (over 90% of rated capacity.) However if you have a long trip your battery will be working over a range of nearly flat to a high point or around 50% (give or take) of rated capacity. This is not good for a battery. Those who have Japanese style AGM batteries (low recombination rates) will be worse off than those with American style high recombination batteries. The low recombination batteries require a higher voltage to charge them than high recombination batteries. This is why Optima batteries work better than Fulriver ones even though they have a lower amp hour rating.
If you are going to give your auxiliary batteries a good work out over a few weeks camping you need a battery booster (DC-DC charger) You will need to travel a few hours most days and your booster should have a DC current out of preferably 1/4 of the rated Ah capacity of your battery.
bods
Member
That's good information. What a lot of people probably don't realise though is the Thailand built d22's have 2 cranking batteries under the bonnet. I have just separated these and put a basic isolator in between them. I know its not an ideal battery to use as an aux for a long time, but for what we use it for at the moment it is fine. When we eventually set the car up for camping longer periods I will look at a decent dc-dc charger and an agm or similar battery as well as a solar panel to mount in the tub for longer periods without moving, I'm also considering a generator to mount into a camper trailer when we eventually get one...
Nomadic Navara
Member
A D22 owner in a D40 forum. Just as well we aren't a bigoted mob here. I was trying to edit my previous bit by adding to the end of it and your message blocked me from doing so. Here follows my attempt.
I have monitored the alternator in my vehicles over the last 20 or so years. They all have the same sort of temperature compensation. You can monitor your system as I have done, get a cigarette lighter plug and make up a way of connecting it to your multimeter. Plug it into a socket that does not have any other loads on its fuse (either of the ones on your dash will do.)
The alternator in my D40 starts at anywhere between 14.4 and 14.7 V on the first start of the day. The 14.7 V was on a very cold day, the lower voltages are on warmer days. It takes less than 10 minutes for the voltage to drop below 14.0 V. The voltage will settle lower when you are towing (if you have a van) than when not towing. I noteed on one afternoon that the voltage was around 13.7 V on the trip over to pick up the van. Later on the way back it was 13.6 V.
How about some others of you do the same sort of testing and post the results here (both D22 and D40 owners.) This should produce a range of results as not all alternators will produce exactly the same results.
bods
Member
it's actually in the general tech area, but anyway...
i know alternators have temperature compensation in them. the newer models even have ecu controlled alternators that will pretty much switch the alternator off to conserve fuel, if you had a recent look through the forum people have noted this on the newer d40's when trying to fit dual battery isolators or dc-dc chargers and they switch off when the ecu drops the voltage.
the voltage monitor on my turbo timer runs off the ignition "on" wire, i have also checked directly on the battery when running and the voltage is within .1v compared to the multimeter.
i know alternators have temperature compensation in them. the newer models even have ecu controlled alternators that will pretty much switch the alternator off to conserve fuel, if you had a recent look through the forum people have noted this on the newer d40's when trying to fit dual battery isolators or dc-dc chargers and they switch off when the ecu drops the voltage.
the voltage monitor on my turbo timer runs off the ignition "on" wire, i have also checked directly on the battery when running and the voltage is within .1v compared to the multimeter.
Smart chargers are the absolute best means of charging batteries. They look at the amount of charge being delivered to the battery and the corresponding voltage, knowing internally what voltage it's applying to its output.
A partially discharged battery will reduce the apparent voltage on the charger's output. By comparing the amount of current being delivered to the battery, what voltage it's trying to deliver and what the voltage being read off the terminals actually is, a smart charger can tell what the state of charge of the battery is.
Our alternators simply can't do this. The regulator keeps the voltage at a certain level and that's pretty much it.
To answer a question raised - my ECU reports my battery voltage generally around 14.1V. At night it drops below 14V. I don't see a lot of variation - perhaps it peaks at 14.2V but rarely do I see it beyond that.
I might get my Torque application to graph it one day.
A partially discharged battery will reduce the apparent voltage on the charger's output. By comparing the amount of current being delivered to the battery, what voltage it's trying to deliver and what the voltage being read off the terminals actually is, a smart charger can tell what the state of charge of the battery is.
Our alternators simply can't do this. The regulator keeps the voltage at a certain level and that's pretty much it.
To answer a question raised - my ECU reports my battery voltage generally around 14.1V. At night it drops below 14V. I don't see a lot of variation - perhaps it peaks at 14.2V but rarely do I see it beyond that.
I might get my Torque application to graph it one day.
DrunkenDamo
Member
After reading this thread a few times i think i got it right i am going to get a Redarc BCDC1220 or a Redarc BCDC1225LV im not sure we will see if we go the solar route aswell, how hard are they to install a can do all the basic stuff mechanically but not so much electrical wise dont want to short anything out or blow anything up 
, this will be paired with a Optima Yellow top, in the tray. How much would a auto elecy charge to install roughly??
, this will be paired with a Optima Yellow top, in the tray. How much would a auto elecy charge to install roughly??
The biggest two things to remember when installing any car electrical system are:
1) Make sure you put a fuse close to the battery before any cable run
2) Use cable of a decent size - don't skimp, and don't believe the label. 8Ga cable is rated for 56A and has a cross-section of 14mm2. How does 2mm2 cable carry 60A as well? Answer - it doesn't. It will take it, heat up, melt the insulator, short out and cause a fire.
Your cable runs should be protected from debris (even a highway has things like roadkill, sticks, gravel chips, shredded retreads etc). Run the cable along as safe a path as possible under the vehicle. Anywhere you have to pass through a piece of metal frame, use rubber grommets to prevent chafing.
If you intend to submerge the vehicle, you might consider coating the electrical connections in that blue spray stuff that auto electricians use on battery terminals.
Other than that, black is negative is chassis, red is positive and should never touch chassis and that's all ya need to know!
1) Make sure you put a fuse close to the battery before any cable run
2) Use cable of a decent size - don't skimp, and don't believe the label. 8Ga cable is rated for 56A and has a cross-section of 14mm2. How does 2mm2 cable carry 60A as well? Answer - it doesn't. It will take it, heat up, melt the insulator, short out and cause a fire.
Your cable runs should be protected from debris (even a highway has things like roadkill, sticks, gravel chips, shredded retreads etc). Run the cable along as safe a path as possible under the vehicle. Anywhere you have to pass through a piece of metal frame, use rubber grommets to prevent chafing.
If you intend to submerge the vehicle, you might consider coating the electrical connections in that blue spray stuff that auto electricians use on battery terminals.
Other than that, black is negative is chassis, red is positive and should never touch chassis and that's all ya need to know!
Hi d22 king.
I have mounted my second battery under the bonnet of my d40 and theirs less room in those than the d22 all you need to do is remove the air box assembly and fit it behind the passenger headlight on a battery tray not a box. You then need to think about the filter setup I have keep my air flow sensor under the bonnet and got a custom stainless snorkle made and fabricated a housing for a pod filter to replace the air ram style head on the snorkle it doesnt look bulky not to noisy and no loss of performance.
Hope this helps
Happy building
Canon909
Hey Canon, any chance you can post some photo's of your second battery setup. Was thinking of doing something similar.
d40ryan
Member
Ok so my plan is to run a solar setup and I will be running it through a ctek smart charger. Now for my second battery that will be running fridge and other items can I use a 200 ah starter battery or am I better off running a deep cycle as I can get the 200ah starter battery for cheap will it be fine to use it as a second battery/deep cycle?
Some do. Early 2012 was when they changed, I think. Check your voltage about half an hour into a drive, it should settle below 13V. Non-smart alternators stick to around 14.3-14.4V.
I'v never seen a full starter that has any ah, just ca & cca. Battery like Yellow top as duel use so they have deep cycle ah, ca/cca not alot of amp hours tho. 200ah is alot you'll probably never need that much. But better to go a full deep cycle battery.
Had a felling you'd say that. Makes most duel battery system useless
I pulled the piranha DB-180 off my triton before i traded it , picked up a new Optima d34 battery last week and will be getting the piranha chassis mount battery tray later this week , another job for the weekend if its not too cold , iam still thawing after last weekend working under the bloody truck
