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[mikerezny]

OUTPUT voltage into Setec is set at 14.8 volts and output current limited to 6 amps.

Hi @Boots in Action,
apologies if I have not understood something.

Does the output of your mini dc-dc convertor feed into the AUX input of the Setec?

If so, in the Setec, there is a diode in series with that input that will have a voltage drop that needs to be taken into account.
I suspect it will be a normal silicon diode and will thus have a forward voltage drop of 0.7V. I don't rely on the car alternator for charging the van battery so I have never bothered to measure the voltage drop.

So, assuming you are using the AUX input, 14.8V output from the dc-dc convertor will be only 14.1V at the battery. This is probably less than optimal for bulk charging deep cycle batteries. The specs for the Ritar GEL I have state 14.2V to 14.4V for bulk charging.

take care
Mike

 

[Boots in Action]

Hi @Boots in Action,
apologies if I have not understood something.

Does the output of your mini dc-dc convertor feed into the AUX input of the Setec?

If so, in the Setec, there is a diode in series with that input that will have a voltage drop that needs to be taken into account.
I suspect it will be a normal silicon diode and will thus have a forward voltage drop of 0.7V. I don't rely on the car alternator for charging the van battery so I have never bothered to measure the voltage drop.

So, assuming you are using the AUX input, 14.8V output from the dc-dc convertor will be only 14.1V at the battery. This is probably less than optimal for bulk charging deep cycle batteries. The specs for the Ritar GEL I have state 14.2V to 14.4V for bulk charging.

take care
Mike

Hi Mike @mikerezny, no you have not misunderstood anything at all. @jazzeddie1234 mentioned to me about a small circuit board he is playing with, with a buck boost converter that was capable of taking any voltage from 5 volts to 32 volts input and changing it to an output of the same voltage, a lower voltage or a higher voltage than was input. Output is rated up to 10 amps (130 watts) but heat dissipation is a problem over 6 amps without extra heat sinking. The links are below.
You and I are fully aware of the power diode in the Setec input circuit which reduces input voltage from tug by approx .7 volt and makes charging from a modern alternator less than effective to charge van battery without some sort of DC-DC step up, and full blown type is too expensive for my limited use and need. So for the low cost of approx $20.00, I thought I would try a little experiment and see if I could get "some" charging current into van battery whilst on the move. The set up of unit is pretty tricky as @jazzeddie1234 found out (as did I too) when adjusting the three mini pots - a low voltage cutout for input, a suitable charging voltage for output and a suitable output current. Even when you get the output voltage where you want it, when you increase the output current , the output voltage drops, and you have to re-adjust again. You are correct in that the unit is in series between the input from tug and the input of Setec. However, the Setec talks about a max (input?) voltage of only 14.8 volts, hence very slowly working up to that input voltage whilst under some sort of load. And another challenge is the low voltage (input) cutout level from tug if there are large variations in voltage from alternator. Send me a PM if you need more info on how I am going. I will send you a picture when fully set up and carefully tested.
Yes, correct in that unless I can input a voltage of approx 15.4 volts from mini DC-DC unit ( and I can get that okay at 6 amps) for effective charging of 14.7 volts for my AGM battery, it is all just a waste of time, but 14.1 volts at best is better than present while battery is low, even if only a small current. But the big question is what about that effect on Setec??
Reverse voltage potential is not a problem as I found out on a demonstration by none other than Julian Ilett.

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[mikerezny]

Hi @Boots in Action,
ok, I now understand the reason to not have the output from the dc-dc convertors to not exceed 14.8V.

As we know, the diode in series with the AUX input is to prevent the van battery being discharged into the car, especially when the starter motor is engaged. Obviously, with a dc-dc convertor in the circuit, this discharge is not possible and the diode is actually superfluous.

So, one obvious solution is to connect the dc-dc convertor directly to the battery terminals. i.e. in exactly the same way one connects a solar panel and regulator. This is detailed in the Setec manual. Further, the same limit for the input voltage is still 14.8V. But in this case, the maximum voltage is now directly across the battery terminals! Thus the dc-dc convertor output voltage can be set to the correct bulk charge voltage for a GEL or AGM battery since they will both be below 14.8V.

From the manual:
Solar power should be connected directly across the battery terminals with a voltage regulator in series. A solar panel voltage regulator with maximum output voltage not exceeding 14.8 volts must be used at all times. Failure to use a voltage regulator may result in power supply damage.

Take care
Mike

 

[Boots in Action]

Hi @Boots in Action,
ok, I now understand the reason to not have the output from the dc-dc convertors to not exceed 14.8V.

As we know, the diode in series with the AUX input is to prevent the van battery being discharged into the car, especially when the starter motor is engaged. Obviously, with a dc-dc convertor in the circuit, this discharge is not possible and the diode is actually superfluous.

So, one obvious solution is to connect the dc-dc convertor directly to the battery terminals. i.e. in exactly the same way one connects a solar panel and regulator. This is detailed in the Setec manual. Further, the same limit for the input voltage is still 14.8V. But in this case, the maximum voltage is now directly across the battery terminals! Thus the dc-dc convertor output voltage can be set to the correct bulk charge voltage for a GEL or AGM battery since they will both be below 14.8V.

From the manual:
Solar power should be connected directly across the battery terminals with a voltage regulator in series. A solar panel voltage regulator with maximum output voltage not exceeding 14.8 volts must be used at all times. Failure to use a voltage regulator may result in power supply damage.

Take care
Mike

Yes @mikerezny , that has been thought through also. The limitation there is that there is no control over the charging voltage/current input like a good solar controller has. The DC-DC unit does not have any such controls. It only does what it is set up for and is not capable of varying the settings automatically like even a basic solar controller. At least going through the Setec, there is some charging sort of control if ever the battery did get up to full capacity.

 

[jazzeddie1234]

It's a great little circuit board. I'm messing about with the voltages because of my overly complicated setup. Here goes...

The tug alternator only powers the fridge (not anything else in the van).

The tug second battery is charged only by solar on the tug. Rarely an issue and I can connect to the alternator if desperate

The second battery powers the van's aux circuits (via pin 2 I think) which includes the setec aux in - now via the ltc.

The van has ample solar so it usually doesn't need any boost from the tug but if the van is in shade I want to use a bit of the tug's surplus solar via the ltc. And with the new lithium batteries I am keen to not float them at 14.6 which the ltc will try to do if it's on all the time.

So the tug second battery floats around 13.7, the ltc cuts in at 13.2, and the setec in is set to 13.9 (giving 13.2 to the battery). The van solar is set to float higher than 13.2 so the ltc only fires up when a) the tug second battery is full and b) the van solar is not working

So far it's working as hoped and it solves another gripe where I used to unplug the 12 pin every stop because the starter battery was drained by the van's aux circuits (breakfree charger, esc circuits, setec inout ) and now it stays plugged in for days or weeks without issue

 

[jazzeddie1234]

Another update and a confession/ brain fade moment

First. I have found a much better way to use the portable fire pit!

I stand the sides on end to make a windbreak. Dig a small trench to the side and sit the grate over that. Now I get a roaring fire in 10mins and can scrape a few coals along the trench to regulate the cooking area ( a variation on how I used to cook). And finally one side makes a great working table for hot pots.

And now the brain fade.
I love this inverter. gets used every day for the toaster, sandwich maker, hair dryer... Brilliant

So why does it keep undervolting when I try to use the microwave!!!! Batteries are fine (12.5v at 150 amps), cables/connections are fine (.2v drop at 150 amps)...
I connect my meter to the inverter input and voltage is nowhere near 9.5v undervolt limit. What is going on....!@#$#. Microwave runs for 90 seconds then microwave shuts down.
I leave the problem for a day (my best fault finding strategy) and open the junction boxes on the backside where the cables connect to the incoming battery leads - via a circuit breaker. Looks fine although the 150amp breaker feels a bit warm... (first clue)
I plug in the water heater because it's 1.5kw load and the inverter runs for 90 seconds, shuts down, pauses, fires up, shuts down... (second clue because the microwave resets at the first shutdown). Wow this 150amp breaker is hot...(ok how is your maths?)
Meter back on the terminals shows 12.5....4....12.4.....4.... Ok it's not the inverter

Then lightening strikes. The breaker is 150 amps and I'm drawing 160ish doooh. I have no idea why I selected 150 when the batteries are fine at 200 but there you go. My only defense is the breaker is interrupting supply and not tripping as expected. A cheap ebay job.

 

[mikerezny]

Another update and a confession/ brain fade moment

First. I have found a much better way to use the portable fire pit!
View attachment 67455
I stand the sides on end to make a windbreak. Dig a small trench to the side and sit the grate over that. Now I get a roaring fire in 10mins and can scrape a few coals along the trench to regulate the cooking area ( a variation on how I used to cook). And finally one side makes a great working table for hot pots.

And now the brain fade.
View attachment 67456 I love this inverter. gets used every day for the toaster, sandwich maker, hair dryer... Brilliant

So why does it keep undervolting when I try to use the microwave!!!! Batteries are fine (12.5v at 150 amps), cables/connections are fine (.2v drop at 150 amps)...
I connect my meter to the inverter input and voltage is nowhere near 9.5v undervolt limit. What is going on....!@#$#. Microwave runs for 90 seconds then microwave shuts down.
I leave the problem for a day (my best fault finding strategy) and open the junction boxes on the backside where the cables connect to the incoming battery leads - via a circuit breaker. Looks fine although the 150amp breaker feels a bit warm... (first clue)
I plug in the water heater because it's 1.5kw load and the inverter runs for 90 seconds, shuts down, pauses, fires up, shuts down... (second clue because the microwave resets at the first shutdown). Wow this 150amp breaker is hot...(ok how is your maths?)
Meter back on the terminals shows 12.5....4....12.4.....4.... Ok it's not the inverter

Then lightening strikes. The breaker is 150 amps and I'm drawing 160ish doooh. I have no idea why I selected 150 when the batteries are fine at 200 but there you go. My only defense is the breaker is interrupting supply and not tripping as expected. A cheap ebay job.

Hi,
have a careful look at the instruction manual for the inverter. Does it specifically state that an external inline circuit breaker is required.

1,500W at 240V would possibly be up to 1,650W needed at the input. At 12.4V, that would be about 133A.

One possibility is that your meter is display average voltage and it is missing the quick drop in voltage slower than the inverter is cutting out.
Another is that the circuit breaker is causing it. You need to measure the voltage across the breaker. If it is getting hot, there will have to be a voltage drop. You could carefully check it is not bad cable termination.

You can check this out by bypassing the circuit breaker and connecting both cables on one side of the breaker. Run the microwave and check the temperature of the terminations. They should not be getting warm at all.

Get hold of an analog multimeter and wire it across the input terminals to the inverter. Use alligator clips so the meter is permanently across the input. Now go experiment again and keep your eyes glued on the needle and observe the reading. Analog meters are much better at detecting transient changes in voltage. Another good device is a 12V test lamp or any small wattage incandescent lamp. Your eye can detect minute fluctuations in brightness.

My bet is that you are indeed getting the LVD because of low input voltage. Another test is to get a smaller appliance, 1,000W, 750W that the inverter will run longer. Then measure the inverter input voltage. You state that at a draw of 1,500W the inverter cuts out at 90s. It is probable that the inverter will cut out at 180s (probably a bit longer) when powering 750W, and cut out around 135s powering a 1,000W load.

As it is, I am surprised that you have a battery that will still be at 12.4V when supplying 130A or so. I would have expected it to be lower.

take care
Mike

 

[jazzeddie1234]

Thanks . My meter was quick enough to show an interruption was happening on the inverter side of the breaker. And 90 seconds for a thermal breaker suggests it was just over 150amps draw - 1.5x is 40 seconds to trip from memory of breaker curves. My clamp meter is too awkward to fit so just using watts/voltage to estimate. The batteries are holding well but the interruption is masking the drop in voltage - although it wasn't dropping fast.

Yes the breaker will come out next time we are home but the inverter is fine at 1.2kw for the sandwich maker so it will do for now. I can also run the microwave in 30 sec bursts with no issue (as cleverly discovered by my wife) so we have a plan B - or the generator...

It was just funny that a few weeks ago I watched a youtube on faulty, cheap 12v circuit breakers

 

[Boots in Action]

Thanks . My meter was quick enough to show an interruption was happening on the inverter side of the breaker. And 90 seconds for a thermal breaker suggests it was just over 150amps draw - 1.5x is 40 seconds to trip from memory of breaker curves. My clamp meter is too awkward to fit so just using watts/voltage to estimate. The batteries are holding well but the interruption is masking the drop in voltage - although it wasn't dropping fast.

Yes the breaker will come out next time we are home but the inverter is fine at 1.2kw for the sandwich maker so it will do for now. I can also run the microwave in 30 sec bursts with no issue (as cleverly discovered by my wife) so we have a plan B - or the generator...

It was just funny that a few weeks ago I watched a youtube on faulty, cheap 12v circuit breakers

Some so called "circuit breakers" are really only circuit interupters and do not fully disconnect/break the circuit. If their rating is exceeded, they get hot very quickly and disconnect circuit until they cool down. This ranges from millisecs to minutes. Years ago, some cars had this arrangement with the headlight protection circuit. If too much current was passed through the unit,) or a short circuit developed) , it did not fully trip out - just stayed disconnected for a few seconds until cooled and then automatically reconnected circuit. Something to do with never being totally in the dark with no lights at all, just shutting current off, then on again at very short intervals. The only full tripping unit is I know is in 240 volt ac line with the RCD. It does "trip out" and stays out until "reset manually". Some fuses are similar. They trip out and have to be manually pushed back in.
As @mikerezny said, heat in any circuit is an indication of too much current in insufficient capacity wiring or a high resistance connection. Also as voltage drops, current will increase if load remains the same. This will occur as you get towards the limits of any equipment. And don't disregard "start up" currents for appliances as these can be significant in a battery system. We don't notice or consider this when connected to grid as plenty of reserve in household electrics.

 

[DRW]

@Boots in Action older Holden’s and falcons had a circuit breaker in the headlight switch they usually started cutting out when people fitted driving lights without a relay or put H4 headlight replacements in with 100w globed

 

[mikerezny]

@Boots in Action older Holden’s and falcons had a circuit breaker in the headlight switch they usually started cutting out when people fitted driving lights without a relay or put H4 headlight replacements in with 100w globed

Hi @DRW ,
also problems with getting enough current out of the generator to power the driving lights.

In the early seventies, I went through the GE catalog looking for the best sealed beams I could find. Ended up buying two 250W. 12V aircraft landing lights. Boy, were they bright. Wired them directly to the battery using huge cable and a relay to make sure there was minimal voltage drop.

But I forgot that the generator wasn't capable of supplying the extra 500W!!!!!. With a bit of fiddling, I did manage to get it all working really well with one 250W spotlight. This was my third car. A Holden FC manufactured in the late 50's.

One side effect was that I never had any trouble getting any oncoming vehicle to dip its headlights!

take care
Mike

 

[DRW]

Lol 16A generator probably Bosch and I’ve probably got a set of brushes and bearings in the she that fit it

 

[mikerezny]

Lol 16A generator probably Bosch and I’ve probably got a set of brushes and bearings in the she that fit it

My great mate next door has an old Falcon and all the spares for it that you could ever imagine. I have done well over the years. The front generator bearing fitted my pool pump motor. And his wheel bearings fit my Penguin.

 

[Drover]

I was thinking that the microwave might be wanting heaps more juice at start up unlike a hair dryer or toaster..... have you tried it on lower power settings to see . I know my Genny gives a big groan when I first flick the coffee pod machine on................

Ha, I have seen the the wires to the landing lights melt on mates Cruiser, was something to see, smoke, then flame, then fizz he used normal old twin flex for bed lamps ............. on the Mini turn spotties on and engine would start to miss.

 

[Dutchy and Tan]

A few weeks on the road so time to review my mods!

Wood carrier: 8/10 works as hoped. I collect enough for the evening a few ks from the camp. Stays put even
Ozito chain saw: 10/10 what a great device. Cuts slow but so much easier than chopping
Fixed solar panels from sunyee: 9/10 Producing good current in low sun. Ute lid one keeps the tug batteries fully charged and the ute fridge running 24/7
Ute lid gas springs: 5/10 Too strong but they are fine for now. Don't get in the way too much
DC DC circuit board: 7/10 only because I haven't found the best output voltage into the setec aux to compliment the mppt settings (which I'm still working on), or the best LV cutoff from the tug. So not really a complaint about the board!
Fire pit: 6/10 great to cook over but not to sit around. Perfect for overnight stops where a billy and a pot need quick heating
Batteries: 10/10 Lithium batteries are just awesome! Stable voltage, plenty of current in and out, but I'm still messing with bulk/float on the mppts

And the winner?

The Inverter! A last minute idea that is used almost every day. Toaster, sandwich maker, hair straighteners, microwave..... What an awesome device. I've only used the gene once this trip whereas I used it most nights last time.

Hi Jazzeddie
I have just bought 2 135 ah powerant lifepo4
batteries . Are you still happy with your batteries . Very hard to find info online on them but they weigh around 12.8 kgs each so hopefully good.

 

[jazzeddie1234]

Mine work great. Also worried about the lack of reviews so emailed the seller to warn them I would do a full test and send them back if they didn't perform. I tested them at 100 amps - no issues - then at 50 amps for 2 hours (100 ah) - no issues. I don't have a method to test high current charging but they recover quickly. So a big tick from me.

 

[jazzeddie1234]

View attachment 66515 Batteries arrived well packed but no documentation other than the stuff on the side. Weighs 10.4kg - not 11.5kg on listing.

View attachment 66516 Batteries are often shipped at 50% so I'm encouraged this one soaked up 50ah. Now it's on load to measure capacity. BTW the giantz 20a charger is really a 12a charger but that's ebay for you

These batteries are back on ebay at $420 if anyone is interested. Mine are performing really well

 

[jazzeddie1234]

Time to start work on the caravan again I guess. The whole of January was consumed by a meltdown over my usual unload everything into the garage. I decided something better was required so the shed got a clean out, the garage got new shelves up high so the camping gear is all stored away and I can find my tools again.


First job was vehicle maintenance so new engine and transfer case oils, drive shaft grease and a wheel alignment.
Very minor toe out which was corrected by a 1/4 turn on the steering arms.

Started on a design for a small 50mm fridge compartment fan that seems (according to youtube) to help with more consistent fridge temps. The hardest part has been figuring out how to power it. Spent several happy hours trying to chase a wire down the thermistor hole so it's down the water drain for now


But then I got looking at the rats nest behind the fridge so I ripped out the jayco wiring (12v spade on board to spade in connector to screw terminal to 12v high current cable) and replaced with 12v spade (my temp repair is holding up better than expected) to anderson to 12v high current cable. I also replaced the fridge low current connector and sleeved all the low current wiring.

Haven't taken a pic because it's not much tidier! But the fridge works still.

Next job is respraying my ute tray hard lid. It's been a long time since a used a spray gun so I better practice before trying the expensive matched paint. Yes the solar panel I sprayed to match has to come off again

 

[Boots in Action]

Time to start work on the caravan again I guess. The whole of January was consumed by a meltdown over my usual unload everything into the garage. I decided something better was required so the shed got a clean out, the garage got new shelves up high so the camping gear is all stored away and I can find my tools again.


First job was vehicle maintenance so new engine and transfer case oils, drive shaft grease and a wheel alignment.
View attachment 68085 Very minor toe out which was corrected by a 1/4 turn on the steering arms.

Started on a design for a small 50mm fridge compartment fan that seems (according to youtube) to help with more consistent fridge temps. The hardest part has been figuring out how to power it. Spent several happy hours trying to chase a wire down the thermistor hole so it's down the water drain for now

View attachment 68084
But then I got looking at the rats nest behind the fridge so I ripped out the jayco wiring (12v spade on board to spade in connector to screw terminal to 12v high current cable) and replaced with 12v spade (my temp repair is holding up better than expected) to anderson to 12v high current cable. I also replaced the fridge low current connector and sleeved all the low current wiring.

View attachment 68086 Haven't taken a pic because it's not much tidier! But the fridge works still.

Next job is respraying my ute tray hard lid. It's been a long time since a used a spray gun so I better practice before trying the expensive matched paint. Yes the solar panel I sprayed to match has to come off again
View attachment 68087

Hi @jazzeddie1234 , I can vouch for the better and consistent temperatures in the bottom of my Thetford 3 way fridge as I have had 12 volt computer fans in there for sometime now. I made 20mm standoffs for the fans, and after cutting a circular hole in the backing plastic sheeting, and fitted velcro to the back. Attached both fans to wall of fridge also with the velcro so they stick on well and no need to drill holes in fridge walls. Wiring for each fan goes out through the thermostat tube hole and then down the back of fridge, a bit of a task and patience required too!. Wired to separate switches inside van so control always available. Advantages are significant, especially as the "better half" no longer complains about frozen lettuce, tomatoes, cucumbers etc. Happy wife equals happy life!!!! Have not once had any hassles with frozen vegies etc since fitting fans and temperature much more even. There is a need to have a switch in line, so that you can turn off the internal fans when opening the fridge door. Enough cold air drops out of bottom of fridge whenever you open the door without the internal fans pushing more out. I believe recovery is faster too as cold air from the evaporator at the top is moved more evenly. You may be able to hook the lines up through the internal fridge light switch on the door (@Drover did this I think???) but I don't have a switched internal light. Have used a strip of LEDs and run a separate switched line for that. The top switch is for the internal LED lights, the middle switch is for the internal fans and the bottom switch is for the twin 120mm external fans at back of fridge to improve movement of hot air from pipes and condenser . These are also thermally controlled. See attached photos.

PS. I have done the check on the possible change of the power diode on the auxiliary input for the Setec and will provide a full report when I get back from 5 days in the Connondales again.

 

[jazzeddie1234]

I desperately want to run the power that way but multiple attempts in both directions have failed. I can push a stiff whipper snipper cord up from the back but not out the hole in the compartment and I can't even start a run from that end. I tried using a thin fishing line and a vacuum cleaner with no success from either end. The thermistor cable moves freely so it's driving me crazy. I did wonder about being brave and pulling that cable out with a leader attached but that is another day.

We are melting here with weeks of high temperatures and not much energy to work outside