Dual battery setup for 2.8 1GD

[InnerCityBoy Junior Member Find all posts View Profile Close InnerCityBoy]

I need to visit Toyota within the next few days, I'll see if a service manual is available for the 2.8ltr whilst I'm there.

Very interested to find out how it goes, Leigh.

It's a lot of ... ahem ... 'fun' trying to work out the best electrical set-up for my 2.8 Prado + camper trailer by going through this forum and others (like MySwag). Decisions I've made (or almost made):

- How to mount under-bonnet: older 150s apparently needed a tray to avoid cracking the guard and some bending of the aircon pipe; 2.8 150 has a flat pipe and reportedly stronger guards, so I've mounted direct.
- What battery under-bonnet: many AGMs reported to suffer in the heat, although a number of premium brands (like Optima) appear to be OK; either way I went with a wet-cell deep cycle to save a bit of money.
- What isolator: I went with a Redarc SBI on sparky's recommendation and good reputation; however some permit allow more discharge from the starter battery than the SBI thus access to more power.
- What battery in the camper: AGMs definitely the recommended option, brands like Fullriver and Optima get the most thumbs up; I've decided on a SSB AGM due to overall good reviews, 3 yr warranty (vs. 1 yr on most) and ability to put under-bonnet should I want to in the future (under-bonnet voids the warranty on many AGMs)
- Voltage booster for under-bonnet AUX: doesn't appear to be essential, as my own (rudimentary) testing shows the under-bonnet battery appears to charge from mid-11v to full in 2 hrs, but for me I think the benefit of having a faster charge when are worth the investment ... IF one becomes available for the 2.8!
- Wiring from the car to the camper: my Anderson plug comes off the AUX under-bonnet battery, not directly from the alternator which I though was sensible to ensure the starter was isolated; bad move from a redundancy point of view, when my (old) camper battery failed last trip, it drained the AUX (while I was driving), leaving me with a dead under-bonnet and a dead camper battery. Am getting this changed to have the rear Anderson in the Prado come off the alternator.
- Low-voltage cut-off: don't seem to be talked about too much, but these look like an essential addition for a (relatively) expensive AGM battery. Am going to get a Projecta 30A model that allows me to change the low-voltage level so I have options to get the best settings.
- Solar charging: the debate about PWM vs. MPPT chargers is just as heated as the DCDC vs. booster debate. Opinion seems to be that MPPT are better for flatter batteries and for panels 150w or above; there is little difference if batteries are mostly charged or if using smaller solar panels. All I can say is that the built-in (cheap) regulator on my 150w panels showed no evidence of putting any noticeable charge in to my battery (on an overcast day) when running a small fridge (pulling around 1.5A according to my multimeter); am going to do more testing but I'm pretty convinced I need either a good quality PWM or MPPT to get anything decent out of the panels.
- DC/DC charger for the camper: this decision is still doing my head in. I thought a DC charger was the go here to compensate for the (supposed) voltage drop over the cable to the trailer, and also the built-in MPPT charger for solar looked like it would also solve my need for a better solar regulator. I first looked at a CTEK 250s, but it wouldn't work on a Prado with a smart alternator without also buying a costly CTEK Smart Pass (THIS WAS SOME TIME AGO AND MAY NOT STILL BE CORRECT). I am still considering a Redarc 1225LV, but note it's MPPT won't work well in poor light or with some panel sizes / brands (due to the minimum of 17.5v off the solar panels as noted by Leigh above and in forums elsewhere), and I also note above opinions that the alternator will push through more than the Redarc will to a trailer battery, at least in the early part of the charge cycle (and I have 6 B&S wiring in my camper between the Anderson to the battery, so I would have thought I'd get a pretty good current through).

Decisions, decisions ... a booster diode (if / when available) + a good quality PWM / MPPT, or a DC charger with built-in MPPT ... I keep swaying between them.

Anyway, hope this essay on 'my journey' is somewhat helpful to others.

[Mild7 Junior Member Find all posts View Profile Close Mild7]

Interesting thread, wish I had have found it earlier..

InnerCityBoy,
I have a 2.8 1GD and have gone with a similar approach to you.

Using an SBi12 with 35mm2 cabling from standard starter battery to a Century Marine Pro 620 (NS70 size, could have gone bigger I think) mounted directly to the car in the same way the starter battery is factory installed, with a trimmed down plastic battery box from an old NW Pajero. Seems to work nicely and has not moved in 2 months since install. Cabling may be overkill, but I do enjoy over-engineering. I also plan to use the override function, and may link for winching some day, so figured 35mm2 cable would be best in the long term. Will use 6B&S to rear, but want to first make sure the system works as designed before having to rely on it.

I have been monitoring voltage via a Scangauge II since October and can confirm the voltage has not dropped below 13.4v in ANY conditions. Hot Summer, near zero at Hotham, A/C on, off, lights on/off, etc etc. It will fluctuate up to 13.9 at times, but very rarely. I bought a diode fuse from Leigh back in November, but found there was no appropriate fuse location suitable to install it in. After much discussion with Leigh, he insisted on returning the device and refunding my money, so I don't doubt his motives in the slightest.

My DBS will be up and running by the end of this weekend with luck, and I will be monitoring voltages with scangauge and Projecta DBM100. I will report back with more relevant information unless already covered by other members in the meantime. I am expecting that this system may require the assistance of a diode, and if one becomes available I will definitely be installing one. Hopefully I wont need a DCDC device as I want to keep the system as simple and uncluttered as possible.

Mike.

[Puddock Junior Member Find all posts View Profile Close Puddock]

Any recommendations (or place to avoid) in Sydney for someone to fit a dual battery system in a 2.8 GD?

Got one quote so far from ABR Kirrawee.

Looking at under bonnet 12v outlet in boot and Anderson plug in vicinity of towbar plug to power caravan fridge?

[InnerCityBoy Junior Member Find all posts View Profile Close InnerCityBoy]

Any recommendations (or place to avoid) in Sydney for someone to fit a dual battery system in a 2.8 GD?

Got one quote so far from ABR Kirrawee.

I got my dual battery and brake controller installed by an auto elec in Kirawee (not ARB) and they did a dreadful job with both. Will PM you their name so you know to avoid!

If you get a good recommendation, feel free to share ...

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

Don't keep the info to a PM InnerCityBoy, let everyone know so they don't make the same mistake. That's what the forum is for !

[InnerCityBoy Junior Member Find all posts View Profile Close InnerCityBoy]

Don't keep the info to a PM InnerCityBoy, let everyone know so they don't make the same mistake. That's what the forum is for !

Happy to once I've had a second auto-electrician confirm the problem with the dual battery ... I don't want to bag a small business on a public forum unless I know the facts are right

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

Hi all,

I'm still researching the charging system in the new 2.8Ltr Prado, and currently chasing a service
manual up for one. Would someone who has recently purchased a 2.8Ltr Prado be able to PM me
the Vin number and possibly the registration number of your car so that I can ensure they order
in the correct item?

Cheers
Leigh

[InnerCityBoy Junior Member Find all posts View Profile Close InnerCityBoy]

Sent ... good luck

[HutHeavy Lurker Find all posts View Profile Close HutHeavy]

I know with the D4-D 3.0L diesel models, a BCDC charger is required due to the alternator being a temp compensating unit. Using a normal SBI isolator, the AUX battery never reaches 100% charge. I would imagine the 2.8L would run a similar setup for the alternator, I recommend a BCDC charger as the gold standard for AUX battery charging. More versatile and can charge straight from solar panel without a regulator.

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

Looks like yet another troll looking for a bite.............

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

Looks like yet another troll looking for a bite.............

And an auto electrician to boot.

Shame he doesn't know his own profession!!!!!!!

[InnerCityBoy Junior Member Find all posts View Profile Close InnerCityBoy]

Ahem ... moving right along ... can I get a hand with my diagnosis of my dual battery system? I'm really struggling to believe the auto electrician has done what I think he has done.

When the sparky talked me through his installation, he pointed out the under-bonnet AUX battery and a load wire with in-line fuse (running to a new rear cig socket + Anderson plug) coming off the back terminal of the SBI isolator. So I expected the rear socket + Anderson would be powered off the AUX as I had asked.

In reality, the rear socket and Anderson only receive power when the isolator is open (ie. the led on the SBI is on). When the led goes out, the rear socket and Anderson are dead. Even more worryingly, using a resistance test on the multimeter shows the AUX positive terminal is connected to the starter positive terminal when the SBI is off.

My conclusion is that the AUX has somehow been wired to the wrong end of the SBI, does that sound right? It seems such a ridiculous mistake for a sparky to make that there surely must be another explanation. I haven't unpeeled it all because I think I'm going to take it back.

Have attached a photo for what it's, the 'load' wire to the socket + Anderson has the inline fuse. The additional wire on the front terminal of the SBI is wired through to the trailer plug (for the electric brakes). At least that's what I was told, who knows what is actually going on ... !

Cheers

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

Hi ICB, if you can, can you post up some more pics.

Just from that one, it would seem the “AUTO ELEC” should stick to painting fences.

The isolator is not only wired up incorrectly but the cabling, read WIRES, are way to thin, so do not use that setup till you have it fixed.

I personally, would not go back to that clown, but you have spent good money so you need a good result.

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

Agree with drivesafe, unfortunately the autoelect obviously has no idea what his doing.

Question now is do you specify exactly what you want and watch him do it, or take it
to anothe autoelec that knows what his doing?

Cheers
Leigh

[InnerCityBoy Junior Member Find all posts View Profile Close InnerCityBoy]

I went back to him just now, he had in fact wired the aux to the wrong side of the SBI. He fixed it straight away and was quite embarrassed about it. Combined with the fact he also managed to partially disable my brakes when he installed the TowPro, I don't think I will be returning to [redacted] anytime soon ... unless something else breaks

Am going to find someone else to make some future mods but at least it should now actually work!

Thanks for your help guys.