It would seem from the voltage readings given that they have retained the standard
alternator setup, the fuse box changes may be in prepartion to a change to a smart
alternator down the track
After several 4 hr drives, the most charge my dual battery shows (a new Century marine deep cycle, in a 2.8 TD, wired through a Redarc isolator with no booster or DC charger) is 12.4-12.5v. Am interested to hear if others have had the same results ... I suspect the 2.8 is just like the 3.0 and needs a booster or DC charger to fully charge a second battery off the alternator.
Sounds like the isolator is not turning on, what was the voltage on the cranking battery?
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Hi Sim and unfortunately, there is not enough info supplied to be able to get any sold evidence of whether the battery is being charged or not.
We need additional info like -
Do you know how low the battery was when you started your drives?
Do you know if the battery is normally kept in a fully charged state when not in use, and this applies to the battery if it is in your daily drive vehicle?
How long after you turned your motor off did you take the voltage readings?
As Leigh posted, what was the voltage at the cranking battery at the end of your 4 hour drives, while the motor was still running.
These questions can help establish if the battery is actually getting a good charge or not, because the info you have posted indicates the battery is at around 85 to 90% charged and thats not bad, regardless of how you charge the battery.
But again, this also depends on how low the battery was when you started out.
Sorry guys I need to do more tests ... I didn't measure the starter battery at the same time (it's reading 12.7 off the terminals, switched off, several hours after 3 hrs driving today) and I took out the second battery out prior to reading this for unrelated reasons with my camper, so can't re-check the readings.
I also noticed my multimeter (off the terminals) gives slightly higher readings (~0.2 to 0.3) than the cheap-o voltage tester through the cigarette socket in the battery box so I will do it all again in a few days when I drive north.
This is a complicated process for a newbie, not helped by the fact my auto electrician didn't appear to know what he was doing. If you have any recommendations for a good Sydney auto electrical, feel free to share ...
Hi Sim and unfortunately, there is not enough info supplied to be able to get any sold evidence of whether the battery is being charged or not.
The following was measured in my 2.8 D4D with a multimeter off the battery posts (with no camper or other loads attached); the aux is a 1 mth old Century N70T deep cycle.
Aux battery (before connected under the bonnet) measured 11.6v after running the fridge overnight. After connecting to the car, both starter and aux measured 12.3v with the engine off (I'm guessing the isolator opened).
After 2 hrs highway driving with the car still at at idle, starter and aux measured 13.68/13.52; with the engine switched off 13.11/13.04.
After a further 2 hrs highway driving, both measured 13.15 with the engine off.
I then disconnected the aux to monitor how it holds charge (no loads), after 14 hrs it measured 12.95.
Seems like I'm getting decent charge after all ... although I now need to test how it manages loads.
Some interesting information there which looks promising. Dual battery will be one of my first mods once I get my 2.8 Prado delivered next month so I've been waiting eagerly for more info to be posted.
I note you have the Century N70 as your aux batt which I believe is around 305mm long? Do you have much room left within the aux battery provision? Reason I ask is I'd like to fit my 120ah agm in there which comes in at around 330mm...
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Put a small load on the battery and see what it tests like?
HKB Electronics, manufacturer of the Alternator Voltage Booster, Silver 2008 D4D,Lifted,Underbody protection, Alternator Voltage Booster, Tiger Z winch, Lightforce DL, Air Horns, Tanami Drawers, Drop down fridge slide, Outback cargo barriers, Rotronics dual Battery system, Polaris GPS, HF/UHF/VHF, Radio speaker combiner, Long ranger water tank, Diff breathers, Inverter, Snorkel and others
Over Christmas we did a 1600k Hoilday towing a camper. The hole time driving volts did not go below 13.5 this was measured through my scan gauge.
I do have duals but i run a 20amp redarc dc-dc and all my auxiliary stuff pulls out of secondary ie hid spots, light bar on rhino rack, fridge, camper trailer wiring, redarc tow pro, work lights/rev. I have a volt meter on my secondary and it would charge to 14.5 obviously because of the dc-dc. IMO I think the inverter is the better way to go in this day in age they are small neat and easy to fit
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I note you have the Century N70 as your aux batt which I believe is around 305mm long? Do you have much room left within the aux battery provision? Reason I ask is I'd like to fit my 120ah agm in there which comes in at around 330mm...
Don't have a measure handy but there are a couple of finger-widths left ... you would likely end up with your battery hard up against the radiator hose though.
Fitted an InterVolt duel battery system and tested on a camping trip down south for a week. I had a Waeco CF50 in the back and a camper trailer hooked up with a 120ah AGM battery, solar charging when off the Prado. The battery I fitted is a Bosch DC31 S4, (330L x 172W x 234H, info for lski) no room to spare. I had one issue with the auxilary battery dropping below 12V when someone bumped the control on the Waeco above the 3 setting. Other than that, the voltage stayed above 12.5v, measured intermittently and keeping an eye on the InterVolt Alert voltage. Each day we went off on side trips, so this would have topped up the charge on auxilary battery. I deliberately hooked the Waeco up and dropped the auxilary battery voltage below 12V before we drove for 4 hours.I have kept the Intervolt settings on default, which are:
Combined Voltage 13.7
Isolate Voltage 12.8
Alert Voltage 12.0
Hope this info helps someone.
Over Christmas we did a 1600k Hoilday towing a camper. The hole time driving volts did not go below 13.5 this was measured through my scan gauge.
I do have duals but i run a 20amp redarc dc-dc and all my auxiliary stuff pulls out of secondary ie hid spots, light bar on rhino rack, fridge, camper trailer wiring, redarc tow pro, work lights/rev. I have a volt meter on my secondary and it would charge to 14.5 obviously because of the dc-dc. IMO I think the inverter is the better way to go in this day in age they are small neat and easy to fit
Hi Hally...what do you mean " I think the inverter is the better way to go"...is that something different to a DC-DC charger?
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Over Christmas we did a 1600k Hoilday towing a camper. The hole time driving volts did not go below 13.5 this was measured through my scan gauge.
I do have duals but i run a 20amp redarc dc-dc and all my auxiliary stuff pulls out of secondary ie hid spots, light bar on rhino rack, fridge, camper trailer wiring, redarc tow pro, work lights/rev. I have a volt meter on my secondary and it would charge to 14.5 obviously because of the dc-dc. IMO I think the inverter is the better way to go in this day in age they are small neat and easy to fit
Hi Hally and sorry mate but there is no real info in your post, other than your battery was fully charged, that would indicate your DC/DC device did a better job than an alternator or if you had done the same thing without a DC/DC device, would your alternator also got your battery fully charged as well?
To get a proper comparison, first off you would need to know how low the battery was when you started your drive.
How long was your drive.
And then do the same thing with just your alternator as the charging source.
And even after a drive with an alternator voltage of 13.5v, if this is the voltage at your auxiliary battery, it to could indicate the battery is fully charged.
Hi Hally and sorry mate but there is no real info in your post, other than your battery was fully charged, that would indicate your DC/DC device did a better job than an alternator or if you had done the same thing without a DC/DC device, would your alternator also got your battery fully charged as well?
To get a proper comparison, first off you would need to know how low the battery was when you started your drive.
How long was your drive.
And then do the same thing with just your alternator as the charging source.
And even after a drive with an alternator voltage of 13.5v, if this is the voltage at your auxiliary battery, it to could indicate the battery is fully charged.
Ok then of course Batterys full when left (who would take flat batterys camping)
We were gone for 2 weeks
After a 1 week we changed spots and aux was at 11.9 trailer was 12.3 and start at 12.3 after 4 hr drive both aux and trailer were 14.4 when pulled in to next spot.
The alt was 13.5/13.7 while driving. Being that its a 20 amp dc-dc with both batterys down you can safely say it was pulling 20amp from start battery.
Of course if you used a normal relay then they would be full at 13.7 (because thats all the alt would put in, or would they because what about the amps going in? Remember volts can be a surface charge)
So yes the dc-dc will always charge at a higher rate thats what there supposed to do
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"So yes the dc-dc will always charge at a higher rate thats what there supposed to do"
The fact that it is a 20A charger does not mean it will always be charging at 20A,
an alternator can supply a lot more than the 20 amps your DCDC charger is limited to
when the battery is low.
Even with a lower voltage than the DCDC chargers 14.4V MAX voltage the alternator may be able to replace the "bulk" charge quicker than the DCDC charger, the higher voltage only becomes beneficial when the battery gets above 80%-90% SOC. Your DCDC charger does not start charging at 14.4V, it may only be 12.6V for instance if the battery is low and then gradually rise as the battery charges, it won't get to 14.4V till the battery reaches a SOC of around 80%. The alternator on the other hand will instantly go to around 14.4V then gradually taper down to 13.8V or there abouts as the engine bay warms. If you only discharge your batteries to 80% SOC then the DCDC may be quicker, but if your like most and discharge them to 50% SOC or lower the alternator will replace the bulk charge quicker even at 13.7V.
In the case of a DCDC charger versus a standard alternator or or boosted one in an "in car"
situation the alternator will be much faster. In a trailer setup there won't be much
difference between the alternator and DCDC charger to "Full" charge and if you have more than one 100Ah battery the alternator again will be much faster than a 20A charger given adequate cabling is installed.
I know of quite a few who have removed DCDC chargers as they found the were getting
much better performance from their old VSR setups.
Depending on how you use the setup, even with the low charge voltage of the 2.8 some if not most would be better off sticking with a VSR setup.
HKB Electronics, manufacturer of the Alternator Voltage Booster, Silver 2008 D4D,Lifted,Underbody protection, Alternator Voltage Booster, Tiger Z winch, Lightforce DL, Air Horns, Tanami Drawers, Drop down fridge slide, Outback cargo barriers, Rotronics dual Battery system, Polaris GPS, HF/UHF/VHF, Radio speaker combiner, Long ranger water tank, Diff breathers, Inverter, Snorkel and others
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