I tow with a 2018 Toyota Tacoma Limited and want to install a DC/DC Charger in my trailer to charge my 300AH Lithium Battery while towing.
I have read numerous write ups on various forums where other are having operational issues when installed in a 3rd generation Tacoma.
As the Tacoma has a variable voltage alternator (not sure if smart) and when the voltage drops for economy reasons (ECU) many DC/DC chargers drop out or cycle on and off constantly.
Has anyone had experience with getting something to work and what did you do.
Second question what is the difference between an Isolated and an unisolated DC/DC Charger? When would you buy one type over the other.
No personal experience with the Tacoma but usually wiring remote on/off to ignition + is a solution for smart alternators that donât keep the voltage high enough to charge the batteries. You can find this in the Orion manual. Also the settings may just need to be adjusted until it works effectively.
Isolated is for installations where the starting battery and chassis battery do not share a common ground. Like your situation where there is a truck towing a camper. The truck battery is grounded to its chassis and the camper battery is grounded to the camper chassis.
In contrast a non isolated would be used where both batteries are grounded to the same chassis. Like in a motor home or van.
Thanks for that. I believe you meant where the camper battery is grounded to the camper chassis.
In my case the on/off or IGN/Trigger wire of the DC/DC Charger would be connected to the trailers running light circuit as the trailer lights have to be on to power the backup/reverse camera, so it will by default turn the DC/DC Charger on while towing.
Yes I think the DC/DC Charger settings has something to do with the unit operating under a smart/variable charger situation.
I have yet to see what the actual numbers need to be for these Toyota vehicles.
I have searched the Tacoma World Forums and it has become a huge discussion with no definitive answer.
Thanks for the clarification of the isolated vs the non isolated, this info my clears the way to which line to I need to consider..
Assume the Victron Energy Orion-Tr Smart 12/12-Volt 30 amp 360-Watt DC-DC Charger Isolated (Bluetooth) is the largest in the isolated 12 volt line.
Yes, isolated means that theres two battery circuits which do not share a common ground/negative.
But, as soon as you plug the trailer into the tow vehicle, both grounds will be connected to eachother, so there no longer is any isolation between the two vehicles. Apart from that, also the mechanical connection between the two vehicles, may that be a ball hitch or a nato couplig or whatever, usually is metal on metal (with maybe some grease), so theres also no electrical isolation there.
So its fine to use both a non-isolated or an isolated Orion to charge a trailer-mounted battery with the power coming from the tow vehicle. In any case, choose an Orion Smart, since the non-Smart are not chargers, they are simply power supplies.
However, keep in mind the charge current has to pass through both the positive and negative conductor, so dont rely on the OEMs wiring harness ground conductor for charging, it might be too small for the additional current. I personally would use an Anderson connector which carries both positive and negative of the tow vehicle.
As for the position, i would place the Orion closest to the battery that needs charging, so on the trailer. You want the output to have as little voltage drop as possible. Voltage drop on the input can be compensated for by the Orion.
As for the settings, smart alternators really make it difficult to find the correct settings for the engine shutdown detection, even more so when having long cables on the input. So if you have the option to use a remote on/off signal, for example switched ignition or engine running, then that makes things much easier. Im not sure about US trailer sockets (i guess OP is from the US), but european ones carry a switched positive which can be used for remote on/off on the Orion.
Here is a layout for a Redarc 50A Charger. The Redarc has a on/off (IGN) that in my case can be powered by trailer light circuit or a separate wire run from a keyed source in the tow vehicle.
Other option is to put a battery isolator like Redarcâs SBI12 in the tow vehicle and run the keyed wire to the SB12. The IGN wire at the charger in the trailer would be tied to the 12 volts coming from the tow vehicle. This eliminates the need to run a separate wire to charger from the keyed source. Once power comes to charger from tow vehicle (activated by SBI12) the DC/DC Charger turns on. A more expensive option I would say. Cost of an IGN wire would be much less than the cost of the SBI12 to act as a source to eliminate the need for a separate IGN wire run.
Looking at the Victron Orion TR Smart (12/12/30), or the Orion XS with Bluetooth (12/12/50), This seem to be the better choice, both have remote terminals. Programable to similate Redarcâs IGN wire terminal? This is where my trailer lighting circuit would wire in? The Victron also has a Manual on/off via bluetooth.
Which one of these is the right choice for this build?
Your feedback re smart alternators and the difficulty for setting the Victron to detect engine shut down. I think this is where the issue is, the alternator voltage drops or cycles and the Victron thinks the vehicle shut down turning of the charging (is this a correct assumption). Should be able to set the shutdown and restart similar to the Redarc settings. Their settings pertain to the voltages of the start battery and when the DC/DC Charger needs to drop out?
I have a similar setup for a removable dual battery system in the rear of my 4x4. I chose the Orion XS. It can do up to 50A and more efficient, thereby running cooler. It is also more compact than TR units You can join it into a smart network with your shunt so that it will know the true voltage at the terminals of the battery being charged.
The downside of using the voltage based automatic engine detect system is that the voltage detected at the XS unit input is the alternator voltage less the voltage drop of both the positive and return current paths. You have to set a minimum voltage threshold for the engine detect system. This will be around 13V volts depending on your vehicle and starter battery. Difference to alternator output of, say, 14V sets the maximum volt drop (1V in this case) that can be tolerated and that sets the maximum current that can flow in your cables. The XS unitâs logic will throttle the current it draws to stay above that minimum threshold voltage and keep charging but your charging current can end up quite low. Difficult to explainâŚI hope its clear.
In the case of a trailer mounted setup your charging cables are long and will experience more volt drop.
If your vehicle has a smart alternator that dials back its output under certain operating conditions you will either get low charge currents or the unit will think the engine has stopped and it will stop charging. With this type of alternator the most reliable option may be a stop-start signal tied to the vehicleâs ignition switch. It will then charge when ignition is energised even if the engine is not running. This risks drawing down the starter battery so you have to be mindful of that situation.
My old UZJ100 Landcruiser has a temperature compensated alternator that dials back the alternator voltage when the engine warms up. My XS gets 20A charging when cold but it drops back to around 5 or 6A when the engine warms up. Thicker cables with less volt drop will help but only up to a point. Ultimately I think Iâll need to run that ignition link.
I have heard good things about the Redarc but have never used one. My understanding is that the BCDC unit is also a solar charge controller and will trickle charge the starting battery. Maybe some cool options if you need it but not worth paying for if you donât.
If you are concerned about being able to configure the engine shut down settings the Orion is configurable to the 100th of a volt. So probably about as customizable settings as you can get. I would definitely try to talk you into the Orion XS 50amp. Its is a fantastic unit. I would install it and start messing with the engine detection shut down settings while monitoring the alternator voltage. There is a smart alternator setting. Some smart alternators end up easier to configure than expected. You just keep dropping the voltage setting until it starts charging. If this wont happen then definitely run the ignition on off wire. It can ran to any 12V source that is only on with ignition. So your park lights would be fine as long as they go off when the truck is off.
Lastly, I know Ford Transit has a âFord recommendedâ method of changing the smart alternator to standard operation specifically for this type of situation. Maybe Toyota has the same thing.
Lots of information Thanks. Yes the Redarc is almost 3x higher that the sale price I can get here in Canada on the Victron XS 50 ($387, limited time). THis is feedback I got from the Redarc Rep;
" yes the BCDC smart circuitry stops charging every ~100 Seconds, stopping for a couple of milliseconds to establish what the âno loadâ input voltage is coming from the vehicle. As per the attached manual (see page 25), with the ignition trigger and settings active, if the tested no load voltage is above 12Volts, the BCDC Alpha will continue charging for another ~100 Seconds⌠this cycle continues until the ignition trigger is taken away, when the next ~100 Second test is done, if the voltage reading is below 11.9Volts, the BCDC will turn off."
If the Voltage coming from the Alternator is so low when in Eco Mode, of course no DC/DC Charger will be efficient.
Reading the Victron XS manual section 3.9 - 4. says a lot.
TherealKT, are you suggesting not to tie the remote to the lights unless I absolutely have to if I cannot get the DC/DC to operate right via the Victron settings
âWith this type of alternator the most reliable option may be a stop-start signal tied to the vehicleâs ignition switch. It will then charge when ignition is energised even if the engine is not running. This risks drawing down the starter battery so you have to be mindful of that situationâ.
Yes If I tie to the trailers lights, when the lights are activated via the tow vehicle light switch (has to be connected to tow vehicle) that risk is there.
âyour XS puts out 20A initially, then dropsâ.
For my 300Ah Lithium, my Battery Manufacturer recommends a 20 Amp Charger (minimum I trust, there is no maximum). Not sure what happens when the the charger output is less than the recommended 20 Amps
I contacted my Toyota Dealer and he said the truck will not have a AGM Battery unless I changed it out (I have not).
I asked if the alternator would be considered smart ( nothing at battery post) and he does not believe so lol. The Alternator would stop charging if the Truck battery was fully charged.
He mentioned, adding a DCDC Charger in the trailer both the Lithium and the Truck Battery would have to be fully charged for the Alternator to stop charging.
I donât know for sure that charging a LiFePO4 battery slower than the recommended charging rate will harm it but exceeding the maximum charge rate certainly will. Orion XS allows you to set the maximum permissible current to a value lower than its 50A capacity. Mine is limited to 30A to avoid overstressing the alternator but it never gets there. It peaks at around 20A because of volt drop issues in the supply cabling. My battery is 100Ah . I do have a plan to shorten the cable path. It is already 16 sq.mm.
James, Your cable run on your XS, did you use 4 AWG wire or smaller. Dropping to 20A for a charger set at 30A is quite a drop.
For the Redarc unit, the rep suggested 4 AWG for their 50A unit, even though the specs say 3AWG for 39â - 11".
The XS specs say 4 AWG for up to 10M (32.9 Feet). With line loss, wonder if one should step up a size (2 AWG) at least for the tow vehicle portion (as this is the longest run).
But like you said rolling back the 50A might be a good thing for alternator protection.
My alternator doesnât always have 50A to spare so I limited the XS to 30A. I am using 16 sq.mm cable from the start battery to the rear tow hitch then another 2m from there to battery pack. Nearest non metric equivalent is 5 AWG.
Two Andersen plugs in line and a fuse. The earth path has two lugs onto the chassis exposed to weather. So lots of opportunity for resistance. I have a shorter cable run planned that will run inside the vehicle. This will reduce the number of joints and have them in a cleaner envieonment. I also suspect the alternator earth to battery via engine and chassis may be undersized. It is a known issue on these cars.
The other problem is the temperature compensation on the alternator. It is built into the internal regulator. It can drop the output to 13.3V on a warm day which is not enough to drive a decent current to the XS. I foxed the reg with a schottky diode so it now runs in the 14.6 (cold) to 13.8 volt range which is ok for the AGM start battery and sends a bit more juice to the XS.
The whole point of my original response is that if you use the auto engine run detection feature of the XS then you have only a small tolerance for volt drop. This becomes even more limiting with long cable runs to a trailer via a weather exposed connector near the tow hitch. It is not the volt drop that is limiting the current, it is the control logic of the XS that cannot allow a voltage less than the minimum âengine runningâ setting at the inlet terminal to the XS while it is charging.
When you say the nearest AWG equivalent to 16 sq mm is 5 AWG. So I take it your 5+. Looking at the XS Manual the 16mm would be considered 6AWG and good for a length of no more than 5m.
4 AWG would be 21.1mm and the closest metric would be 20mm. XS manual says the 4 AWG is good for up to 10m (32 Feet). Not sure how much tolerance Iâm looking at here. Not sure how the different wire compositions (# of strands and strand size) play into this). Also how much amperage does the XS actually draw being considered a 50A Charger?
My Tacoma is a short bed double cab, the length of the trailer tongue and the distance to the XS on the wall inside the trailer Iâm pushing 32 if not closer to 36 feet (Pos) The Neg run will utilize the frame (common/floating ground) to save wire. The 4AWG Iâm looking at is 673 strands, I reached out to the seller to see what the distance @ 50amps would be with line loss.
At 30 Feet, it will cost me $35 extra to move to 2AWG. If I dial back the XS to 40A I bet the 4AWG will suit my required length as well.
James, you say you only have 50A to spare on your alternator. How many amps is it rated at and how did you determine your 50 available?
Took a rough measurement and came up with 32 - 34 feet to charger.
Internet search says the Tacoma uses 4 AWG from Neg Terminal to Frame. The 4 AWG Neg from my Anderson plug will tie to the frame near the tow hitch.
Having said that, do I need to run another 4 AWG Neg from the Neg post of the battery ant tie it to the frame near there (front) or can I rely on the existing OEM Ground Wire?
