charging rate

[Big Fella Senior Member Find all posts View Profile Close Big Fella]

Re: charging rate

Hi Big Fella, Leigh pretty well covered it and in your situation, you will never fully charge your batteries using any of the suggestion you listed and that also goes with decent cabling.

I know you probably won’t like this BUT for the short times you drive, the lower your batteries are, the greater the amount of used capacity your alternator and decent sized cabling can replace as compered to anything else.
A 100 Ah flooded wet cell battery with an SoC of 30% will pull close to 30+ amps from an alternator with an operating voltage of just 13.2v and if you add the fact that the first 15 minutes will be at a much higher voltage, then you will be able to replace that much more of the used capacity, using nothing more than your alternator.

Remember, this all depends on the size of your cable and the length of the cable run between your batteries.

As stated previously the cable is good. Next size up that I can see, is to use big mutha welding size cable off our welder gen sets(as big as your thumb). We'll leave the cable issue alone from here on end.

[Big Fella Senior Member Find all posts View Profile Close Big Fella]

Re: charging rate

Now there is one other option not covered and that to use two batteries, and the simplest way to do this is to fit one of my isolators.

Unlike any other dual battery isolator where they separate the cranking battery from the auxiliary battery when the motor is stopped, or soon there after, my isolators keep all the batteries connected and allows the surplus power of your cranking battery to be used to assist the auxiliary battery.

Big fella, in your specific case it could be a huge benefit to how you replace your used stored battery capacity.

Using Leigh’s figures to demonstrate, with your existing set up, you will pull say 28 amperes from a single battery set up but using one of my controllers, while you will still need 28 amperes to meet your need, you will only be taking 14 from each battery.

So now, instead of having a single battery that needs 28 amperes of power to be replace during your 40 minute drive, your auxiliary battery will only be down about half as much as it would normally need to be and even though your cranking battery also needs 14 amperes replaced as well, the fact that your alternator can easily charge both batteries at the same time, you will now only need to drive about 2/3 the amount of time to fully charge both batteries.

In your case as you will not be driving long enough to fully charge the batteries, you will still replace a bit under twice as much of the used capacity BUT because your auxiliary battery was not as low as it would normally be in a single battery set up, you will actually end up with an auxiliary battery that is probably around 85 to 90% charged, in just your 40 minute daily drive.

Note, your cranking battery will be in about the same state.

Right o then.

seeing as I have had a big day getting my head belted about by experts in safety training of gasses I'm feeling a bit woozy reading all that.

The way my poor old brain reads it is as such, remember I'm simple (I love the KISS theory). Buy one of your controlers to replace mine and it will keep both batteries in line and not isolated. Correct?

So to my knowledge if I am to stay 2 days somewhere, what will happen to my ability to start the Prado when both batteries are are discharged to the point of the dreaded click, click, click oh shite the batteies are dead?

Please keep it simple I don't like all the techno stuff. Is the best way to check the state of charge of a battery to use the good ol' turkey baster? That should provide definitive proof if the wet cell battery is being charged correctly. Yes/No?

[AJ120 Out of control poster! Find all posts View Profile Close AJ120]

Re: charging rate

Hi Drivesafe, this thread is starting to give me a headache trying to wrap my brain around it all, i am with Big Fella and like the KISS system for anything to do with electrics. (you never know when you might need to fix it in the middle of knowwhere). Anyway you refer to decent size cabling, what do you call decent :?: , i currently dont have a second battery as i have a eutectic fridge but there is the possibility of a change to a bigger fridge. i will probably mount the second battery in the cargo area.

Cheers Andrew

[drivesafe Senior Member Find all posts View Profile Close drivesafe]

Re: charging rate

Hi again Big fella, sorry about the continual reference to decent sized cable, it just that I have no idea what cable you have and I prefer not make out that my controllers will work with any size cable.

The controllers are designed to work in partnership with the correct cable size, but I won’t mention it again.

Now the way my controller work is that they allow the accessories to spread their current load over both batteries and the surplus capacity of the cranking battery is used until both batteries are down to 50% SoC ( around 12v ), at which point the cranking battery is then isolated.

During the development of these controller, just over 20 years ago, it was found that most vehicles could be started from batteries as low as 11.75v.

There were some old ( as in older 20 years ago ) diesels that would not be started from 11.75v but would easily start from 12v, so thats where we set the cut-out level.

I continually retest the starting voltages of different vehicles and these days I‘ve not found a single vehicle that could not be started off a battery with 11.5v. Note, this is using a health battery, not necessarily new, just healthy.




Hi AJ120, this is just a quick reference to cable sizes but should help you.

Two batteries mounted side by side, 6mm auto ( 4.5mm2 ) with a 35 amp maximum continuos safe working capacity, 6mm auto is the minimum size but this cable will work fine.

Two batteries mounted anywhere in the engine bay, 8B&S ( 7.9mm2 ) with a 65 amp maximum continuos safe working capacity.

With a battery or two, mounted anywhere else in the vehicle or in a camper trailer or caravan, 6B&S ( 13.5mm2 ) with a 90 amp maximum continuos safe working capacity.

Note, for a single battery mounted in the rear of a vehicle, 10mm2 cable will work, but if you decide to add another battery or down the road you also want to charge a battery in a camper trailer or caravan, then you need to replace the 10mm2, so it makes more sense to run 6B&S in the first place.

[winniliss Avid PP Poster! Find all posts View Profile Close winniliss]

Re: charging rate

Hi AJ120, this is just a quick reference to cable sizes but should help you.

Two batteries mounted side by side, 6mm auto ( 4.5mm2 ) with a 35 amp maximum continuos safe working capacity, 6mm auto is the minimum size but this cable will work fine.

Two batteries mounted anywhere in the engine bay, 8B&S ( 7.9mm2 ) with a 65 amp maximum continuos safe working capacity.

With a battery or two, mounted anywhere else in the vehicle or in a camper trailer or caravan, 6B&S ( 13.5mm2 ) with a 90 amp maximum continuos safe working capacity.

Note, for a single battery mounted in the rear of a vehicle, 10mm2 cable will work, but if you decide to add another battery or down the road you also want to charge a battery in a camper trailer or caravan, then you need to replace the 10mm2, so it makes more sense to run 6B&S in the first place.

Thats what we like to see, straight up advice, simple terms and for what application. Lead on the rest of you "professional people in the business" and then let the consumer decide. We need a section for various products that we can buy, for what price and what warranty just so it stays out of the actual forums.

[Rusty62 Advanced Member Find all posts View Profile Close Rusty62]

Re: charging rate

Have just installed the diode / fuse on both a 120 and 150 series D4D's. Cost approx $3 per unit. The 150 now has 14.1 cold and the 120 is 13.9. Far better than the 13.3 - 13.5 we had before.
This would be one of the best and easiest mods to do with a good result. My deep cycle will now reach close to 100% charge giving my 2 + days for the fridge.

[Big Fella Senior Member Find all posts View Profile Close Big Fella]

Re: charging rate

Have just installed the diode / fuse on both a 120 and 150 series D4D's. Cost approx $3 per unit. The 150 now has 14.1 cold and the 120 is 13.9. Far better than the 13.3 - 13.5 we had before.
This would be one of the best and easiest mods to do with a good result. My deep cycle will now reach close to 100% charge giving my 2 + days for the fridge.

Which one did you use mate and where did you get it and i'll grab one.

[Bushbasher Out of control poster! Find all posts View Profile Close Bushbasher]

Re: charging rate

I still don't understand why you run the fridge all the time? Unless you're keeping a 6 pack cold for the drive home each day (I don't condone drink driving) what do you need the fridge on for - you live in NSW not the bloody Sahara desert.

I pre cool my fridge via 240v. If the fridge is in the car then I run the cable from the powerpoint in my carport to the fridge via the back window. Most of the time when I'm not driving out scrub the fridge doesn't live in the car. If I'm going out for a trip I run the charger into the aux battery over night to make sure it's 100%.

Whilst out bush I turn the thermostat down overnight so as not to overly drain the battery. The stuff inside the fridge stays quite cold overnight. I used to run the engine to top up the charge in the batteries a couple of times a day. Now with the solar panels I don't need to do this.

[chester Advanced Member Find all posts View Profile Close chester]

Re: charging rate

Hey guys what would happen if i pugged the diode into a non D4D 120 (old 1kzte) motor i ask cause when i have the van attached and have been camping for a couple of days it is a lot of driving to get the under bonnet aux and van battery charged again. Would i get super voltage or just melted wires

[Rusty62 Advanced Member Find all posts View Profile Close Rusty62]

Re: charging rate

Have just installed the diode / fuse on both a 120 and 150 series D4D's. Cost approx $3 per unit. The 150 now has 14.1 cold and the 120 is 13.9. Far better than the 13.3 - 13.5 we had before.
This would be one of the best and easiest mods to do with a good result. My deep cycle will now reach close to 100% charge giving my 2 + days for the fridge.

Which one did you use mate and where did you get it and i'll grab one.

We made the units at home. They are for sale on ebay for $35 or so.
As for the non D4D prado my old one had a higher charge rate than the D4D. It was 14.1. I don't think i would up the voltage any further.

[tinkera Member Find all posts View Profile Close tinkera]

Re: charging rate

HI Bushbasher. Off topic a bit but what size and how many solar panels are you running to keep your batteries topped up :?: CHEERS TINKERA.

[Bushbasher Out of control poster! Find all posts View Profile Close Bushbasher]

Re: charging rate

HI Bushbasher. Off topic a bit but what size and how many solar panels are you running to keep your batteries topped up :?: CHEERS TINKERA.

I've 2 x 50 watt BP Solar panels that put out a combined 6 amps. These feed into dual N70 size deep cycle batteries. I run the fridge in the car until we get to our campsite then put the fridge into the camper. I'm heading out this weekend for 2 weeks so will give it a good test and see how it all goes.

The panels used to be hinged together with stands. One panel got broken and the replacement is about 10cm shorter so now I have them separated. They feed through a 10amp controller that prevents backward flow of current after sundown. It also cuts out the main power if the battery level gets too low. I can pull one panel away from the camper and hook into my car batteries if necessary.

[tinkera Member Find all posts View Profile Close tinkera]

Re: charging rate

HI Bushbasher thanks for the reply.Sounds like the set up i,ll need shortly.If this is your first trip with this setup I would like to hear how it performed.Your battery setup sounds much like mine,I am just looking for something to keep the camper charged up while we are hold up in one spot ,anyway have a good safe trip.CHEERS TINKERA.

[Ozpat Advanced Member Find all posts View Profile Close Ozpat]

Re: charging rate

Hi Leigh

Just ordered your diode. Hoping it will fix my problem with C-teck dc - dc charger which keeps cutting in and out as the voltage at the charger keeps dropping below the 12.8 cutout. This results in my AGM battery in boot taking many hours of driving to recharge. Where exactly is the ALT-S fuse we have to replace?

Cheers
Ozpat

[LeighW Avid PP Poster! Find all posts View Profile Close LeighW]

Re: charging rate

Hi Ozpat,

Thank you for your purchase, the unit will solve your low voltage issue. I have sold quite a few of
the units and feedback from the users indicates the are very happy with the results their getting using
the Voltage Booster and plain isolators.

The unit comes with detailed installation and testing instructions.

Normally you would expect to see the alternator sitting at around 14.3V ~ 14.4V after installing
the Voltage Booster. The above assume both batteries are fully charged and all accessories are off.

The 12.8V your getting is very low even low for a Prado, was that taken with fully charged batteries
a cold engine bay and no accessory load?

Cheers
LeighW