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Re: Lithium ion phosphate battery
Dave, that behavior is for a lead acid or AGM battery, right?? I believe a Lifepo4 battery, which Bob is thinking of installing, will pull the max 20 amps for the majority of the charging time.
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On Sun, Mar 3, 2024 at 05:25 PM, elegy3983 wrote:
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Re: Lithium ion phosphate battery
开云体育? Good discussion!? One more thought to add: keep in mind that when a 20 amp DC-DC converter/charger is first engaged, its charge current to a partially discharged camper battery is nearly 20 amps (19.5 amp typically) but it only remains at that level for a few seconds, before reducing rapidly to 15 then 10 amps or less.? My setup involves a TV battery/alternator mounted under the hood of my 2018 Ford Escape, with 8 awg positive and negative wires through a 50 amp fuse and 12 volt cut-off relay to the Bargman receptacle/plug and into the camper interior where the DC-DC converter/charger and battery are located aft of the axle.? Despite the distance, the setup works fine, largely because the typical run rate charging current is much less than the rated 20 amps. ? Dave ? P.S.? I agree with this comment: ? Bob, the dc charger pulls up to 50% more current on the input side than it puts out on the output side.? So a 30 amp dc charger can pull 45 amps from the TV, and your harness rated at 30 amps won't handle that.? I'd recommend sticking with 20 amp max.? That only pulls 30 amps max.? |
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Re: Lithium ion phosphate battery
Two comments on that:
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A wire smaller than what renogy recommends can handle the current the dc charger encounters.? But when using a smaller wire, the voltage drop is more, so the dc charger has to work harder to bring the voltage back up, and may either overheat or have sub par performance.? Renody may be a bit conservative on wire sizes for the 20 amp charger.? They say you may need up to a 4 awg wire for a 20 amp charger.? But they say also say 4 awg handles a 60 amp charger.? That seems wrong.? But then again, I'm not an electrician. On Sun, Mar 3, 2024 at 02:34 PM, BobF wrote: Steve, you may be right about sticking with a 20 amp charger to be on the safe side. ? But, the interesting thing I have noticed when looking for relays is that even the ones rated for 30-40 amps only come with 12 gauge wires, some with only 14 gauge wire harnesses.? Why they don't use at least 10 gauge, I don't know!? My concern now is still re if connecting the relay to just any circuit when the ignition is on has the possibility of doing damage to sensitive electronics. |
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Re: Lithium ion phosphate battery
?Jean-Francois,? I also have a new Highlander, although not a hybrid.? Could you please tell me how you found the ignition no 2 fuse and what type of add a circuit connector you used.? If you don't mind, maybe you could send it to my email along with pictures, if it is not too much trouble. ? I am trying to avoid running another wire thru my firewall if possible.? Thanks
?? Bob |
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Re: Lithium ion phosphate battery
Steve, you may be right about sticking with a 20 amp charger to be on the safe side. ? But, the interesting thing I have noticed when looking for relays is that even the ones rated for 30-40 amps only come with 12 gauge wires, some with only 14 gauge wire harnesses.? Why they don't use at least 10 gauge, I don't know!? My concern now is still re if connecting the relay to just any circuit when the ignition is on has the possibility of doing damage to sensitive electronics.
???? Bob |
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Re: Lithium ion phosphate battery
Bob, the dc charger pulls up to 50% more current on the input side than it puts out on the output side.? So a 30 amp dc charger can pull 45 amps from the TV, and your harness rated at 30 amps won't handle that.? I'd recommend sticking with 20 amp max.? That only pulls 30 amps max.?
Plus even if a component is rated for 30 amps, that doesn't mean the dc charger can use it with 30 amps.? The wires have to be big enough that there's no significant voltage drop.? I tried calling renogy and ask what would happen if I used undersized wires.? If it just reduces a 20 amp converter down by a few amps, no big deal.? But if the charger overheats and/or shuts off, then we have a problem.? But the person on the support line wasn't knowledgeable, and couldn't answer my question. I've got to say though, installing thicker power wires to replace the ones in the bargman cable could be difficult.? The renogy specs say you can use 8 awg for 10 to 20 ft of wire.? If your converter and dc charger are in the front corner of your trailer, the wire will be less than 20 ft.? But if they're behind the axle underneath a rear dinette seat like in my trailer, then you'll be well over 20 ft, and then you're supposed to use at least 6 awg.? A 6 awg wire may not fit in the bargman connector.? The bargman connectors on both my car and my trailer would be difficult or impossible to use with a new wire.? The bargman plug on the trailer is factory molded rubber, so you probably have to cut that off and get a new one that wires can be fastened to.? The? bargman receptacle on the car is shrink wrapped, glued, and steel mesh covered. That might come apart, or might need to be replaced too.? Then hopefully after you cut off an existing plug, you have a couple extra inches of cable to fasten on the new plug. |
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Re: Lithium ion phosphate battery
Eugene, Please?provide the URL for this chart. Larry On Sun, Mar 3, 2024 at 2:44?PM Eugene Breindel <efbreindel@...> wrote: Be aware, that 10 gauge wire might not be big enough depending on the length of the run of wire. The greater amount of current that you will want to draw from your DC to DC the greater potential for the voltage drop to be insufficient. |
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Re: Lithium ion phosphate battery
Be aware, that 10 gauge wire might not be big enough depending on the length of the run of wire. The greater amount of current that you will want to draw from your DC to DC the greater potential for the voltage drop to be insufficient.
I attached a copy of the Blue Sea systems 12 volt DC wire chart to this message. DC to DC chargers also tend to create a lot of heat from what I have seen others report. Be careful of the mounting to ensure there is plenty of air flow. Good luck with your project! |
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Re: Lithium ion phosphate battery
Jean-Francois Larin
On Sat, Mar 2, 2024 at 08:20 AM, BobF wrote:
Dave, this sounds like a great idea, but just wondering what you wired the relay to so it would turn off with the engine.? I imagine it would be necessary to find a circuit that is only hot with the ignition on. That is what I did in my past 2 vehicle. On the Venza (2009) there was a accessory +12V (cigar lighter plug) in the back. That one is ON on accessories, so it is on when the engine is running, off when the key is in the off position.? So I connected that on the control pin of the relay/solenoid.? That installation is dangerous, meaning that if you let the car on accessory setting (to listen to radio) then you'd drain the tow vehicle battery.? I did the error once (with a cooler, not a trailer) and will not use accessories for any extended period of time again. On the Highlander Hybrid, I got the Ignition no2 circuit fuse, used a add-a-circuit connector that allows you to tap an extra fuse on an existing one and drive the solenoid/relay with that.? It helps to get the wiring diagram of the tow vehicle to find all the available circuit and find all the possibilities that would be turned on ONLY when the engine is running (or in Ready mode, for hybrid).? So that way, when the engine is turned on (ready) and there is plenty of 12V power, the relay gives that power on the +12V on the 7-pin connector. Otherwise, there is no power on that connector and the tow vehicle is protected. |
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Re: Lithium ion phosphate battery
Thanks again, Dave.? Your solution sounds like maybe the best way to do this type or set-up.? I was thinking, however, of using a 30 amp DC-DC charger as I have a 10 gauge wire coming from the battery and my Pollack wiring harness and connector are rated at 30 amps.? Also, the only exposed wiring on my TV is in the fuse box and appears to be about 20 gauge.? As I am not an electrical engineer, I am a little hesitant about taping into just any circuit in case the extra draw from a relay, although minuscule, might do some damage.? I know the electronics on newer vehicles can be sensitive.
?? Bob |
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Re: Lithium ion phosphate battery
开云体育? Every TV has at least one circuit that is only hot when the ignition is on.? You can find these circuits within the fuse boxes that all modern vehicles have.? Then just tap onto one of these switched voltage sources to power your cut-off relay.? Then the relay cuts-off the current flow from your TV start battery to your DC-DC converter/charger whenever your TV ignition is off. ? The DC-DC exciter connection that ordinarily goes to the very same ignition-on source in your TV is then just jumpered to the positive wire coming from the TV via its cut-off relay using a short length of 14 awg wire. No splicing is required, just a jumper from the exciter terminal on the DC-DC to the positive input terminal on the DC-DC. Saves an extra wire from the camper to the TV. ? BTW, I ran 8awg wiring from TV to camper so that there would be minimal line loss when charging the camper battery via the DC-DC at up to 20 amps. ? Dave ? ? ………………………… ? Dave, this sounds like a great idea, but just wondering what you wired the relay to so it would turn off with the engine.? I imagine it would be necessary to find a circuit that is only hot with the ignition on. Did you then not connect the ignition wire at all on the charger?? From what I read on the Renogy web site the charger will not work unless the ignition wire is connected. |
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Re: Lithium ion phosphate battery
开云体育? I ran into this same dilemma when I installed my DC-DC converter/charger, so I ran 8awg wiring from the TV start battery positive (AND negative too), through a 50 amp fuse and an ignition switched cut-off relay (a 12 volt boiler relay with nice big contacts mounted under the driver’s seat) to the Bargman receptacle on my TV, then from the camper’s Bargman plug to the DC-DC unit. This involves cramming two thick wires into the Bargman receptacle and plug, but it can be done and results in a relatively weatherproof connection (as much as the Bargman assembly ever provides…) ? This solution has been working for years. ? Dave ? …………………. ? I also looked into putting in thicker wires, and tried to find waterproof connectors, so I could disconnect these thicker wires when the trailer wasn't hitched.? I could not find anybody that had waterproof connectors.? |
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Re: Lithium ion phosphate battery
Bob, I think the point that's being missed here is that one wire can be connected to 2 locations.? So if the power wire from the TV to the trailer shuts off when the TV engine shuts off, you can splice two wires on the end of the power wire, and connect one of those to the ignition terminal, and the other to the input power of the dc charger.? Does that make this conversation make sense?
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Be aware that you have two options for how you install the dc charger.? One option is to connect it to the existing power wire in the bargman cable.? In this configuration you have to run the the 20 amp dc charger in 1/2 power mode, because the bargman cable can't handle full power. The other alternative is to run separate fatter wires for power from the TV to the trailer, and then you can run the dc charger to output the full 20 amps. The first option is the easy one to install.? Your bargman power wire most likely already is setup to shut off power when thd TV engine shuts off.? Provided that's true, you cut the + and - power wires coming out of your bargman cable in your trailer, fasten 3 extension wires to the + wire on the vehicle side, then fasten one of those + extensions to the power input on the dc charger, another to the ignition terminal, and another to the current limiting terminal to make the charger run at half power.? Then also connect the - power wire to the - charger input.? Then the other ends of the cut wire fasten to the outputs of the dc charger. On Sat, Mar 2, 2024 at 08:20 AM, BobF wrote: Dave, this sounds like a great idea, but just wondering what you wired the relay to so it would turn off with the engine.? I imagine it would be necessary to find a circuit that is only hot with the ignition on. Did you then not connect the ignition wire at all on the charger?? From what I read on the Renogy web site the charger will not work unless the ignition wire is connected. |
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Re: Lithium ion phosphate battery
Dave, this sounds like a great idea, but just wondering what you wired the relay to so it would turn off with the engine.? I imagine it would be necessary to find a circuit that is only hot with the ignition on. Did you then not connect the ignition wire at all on the charger?? From what I read on the Renogy web site the charger will not work unless the ignition wire is connected.
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Re: Lithium ion phosphate battery
开云体育? I’ve mentioned this before, so let me be clear:? with the Renogy DC-DC converter/charger, the trigger wire does NOT need to be connected via a separate wire to the TV ignition!? Just wire it to the positive incoming wire from the TV, and if you don’t already have one, install a TV mounted cut-off relay in the positive wire coming from the TV battery, that cuts off the current flow from TV battery/alternator to the camper when the TV engine is not running.? Every TV should have a cut-off relay so the TV battery can’t be drained when the rig is parked with TV engine off.? ? I’ve wired my Renogy 20 amp DC-DC converter/charger this way for years with no problem! ? Dave ? ……………………….. ? ...? My original avoidance of wanting to do this is that some of these converters require a wire connected to the tow vehicle ignition switch and I did not want to run an additional wire thru my vehicle to do this.? |
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Re: Lithium ion phosphate battery
Actually, it is legal to tow with propane on in all states.? Its only illegal in some tunnels and on ferries. I saw a survey that said 70% of RVs tow with propane on, because its so difficult to get the fridge running on DC properly.? It may be bad for us, but its a lot worse for the big RVs which have another 20 feet of wire to get to the fridge, and have bigger fridges that draw more power.
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The government also doesn't make any attempt to fix the problem.? They could require thicker power wires running through the tow vehicle, and in the bargman cable.? But they don't, and you can't even buy a bargman cable with a power wire thicker than 10 gauge.? If they had 4 gauge wire in the vehicle and the bargman, you could then easily install a 20 amp dc dc charger in the trailer and the problem would be solved.? Trailers would then probably come with a dc dc charger installed by the trailer manufacturer. They also don't regulate how the propane excess flow shutoff works either.? It also has gotten less effective in the last 5 years too.? It used to be that when the propane shutoff engages, the amount of propane coming out would be only enough to barely light a stove burner.? But when I replaced my propane pigtails last time, I noticed that after the shutoff engaged, the burner still burned as if on its highest setting.? Its also much more difficult to get the excess flow shutoff to engage.? My old pigtails would engage the shutoff if the flow was at the max output by the regulator.? My new pigtails would not shutoff with max regulator output.? So the excess flow shutoff now only works if you cut the propane line between the tank and the regulator -- in other words, if the pigtail is cut.?? I found this out when I tried to find pigtails with a lower max flow shutoff.? I called around asking for better pigtails, and I finally got connected to a guy that knew about propane, and he said nope, they don't shutoff at the max flow supplied by the typical regulator.? Again, this is another area where the government could impose standards that make the excess flow engage with less than max flow put out by the regulator, but they don't.?? I also looked into putting in thicker wires, and tried to find waterproof connectors, so I could disconnect these thicker wires when the trailer wasn't hitched.? I could not find anybody that had waterproof connectors.? One guy had a picture of his setup on his truck, and was using Anderson connectors that are not waterproof.? The connection point was behind the rear wheel, where it would get blasted from tire spray in rain.? Not very impressive.? The fact that I couldn't find good examples of this must mean very few are doing it. So I'm towing with the fridge running on propane, like most others. On Sat, Mar 2, 2024 at 01:44 AM, D Link wrote: Towing your trailer while the propane is burning to operate the refrigerator is not legal in many states, so please investigate carefully before you do this. Also, propane has a habit of blowing out while being towed, which can cause gas buildup inside the trailer. This could be a bomb if a spark ignites it. |
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Re: Electrical Engineer
I'll check that video out, if I haven't already.? ?I built what I believe is a safe rig.? The only thing a master electrician friend of mine was concerned about was the potential a high voltage magnetic field from the high voltage side might induce a higher voltage in the low voltage side if the are close enough together.? I have three intermittent switches that must all be depressed at the same time to power the transformer.? I used it on counter tops I made for the camper.??
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-- Don DeRyke Sunrise, Florida 2009 Classic, 2020 Ford Escape, 2.0 liter EcoBoost, AWD.? Previous TV 2015 Ford Escape 1.6 ltr EcoBoost engine. |
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Re: Lithium ion phosphate battery
Towing your trailer while the propane is burning to operate the refrigerator is not legal in many states, so please investigate carefully before you do this. Also, propane has a habit of blowing out while being towed, which can cause gas buildup inside the trailer. This could be a bomb if a spark ignites it.
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Eugene Breindel
Don DeRyke