2007 190P lithium upgrade

[reilym]

Originally Posted by Treker20

Mike, I am going to make the assumption that VSS means voltage sensitive switch based on your description on how it works. is that correct.

If I remember correctly about something I read from another post about B2B chargers, there is also a terminal that can change the charging amps by half. Could this switch be used to control this rather than just cutting the charger off or on?

I have heard a couple of opinions regarding the 60A B2B charger about wether my 145 A alternator be able to handle the load. If so, being able to toggle back and forth may be a good option. Since i am going to the trouble to change to the lithiums. I would like make the upgrade as highly functioning as possible. RowieBowie says he turns off his B2B charger when he first starts the engine and turns it on manually when he hits the road.

I am going to make another assumption that if temps rise and the alternator is being taxed because of the heat, the voltage will drop and the 60A B2B charger would drop down to 30.

Sorry, I just now saw this question. You are correct about VSS. I am using two of them (see this thread). One turns the DC-DC on through the D terminal with a delay after sensing > 13.2V and off when the voltage is below 12.8. The second one activates the L terminal on the DC-DC, which cuts the output (and input) in half when the input voltage is between 12.8 and 13.2. It activates instantly and turns L off after a delay once the voltage is > 13.2. In addition to the automatic switching provided by the VSS units, I can override everything from switches I installed in the cab, although I normally just let the VSSs do their thing. At the moment, I monitor the alternator temperature via an in-cab display and can either manually cut the current in half or turn the DC-DC off from the cab if it gets too hot. So far, I have not seen the alternator get over 190F, but I have not used the RV in extremely hot temps yet. Ideally, I would add the alternator temperature as another input to control the DC-DC directly, but that is a project for another day. I know there are alternators that have output attenuation based on temperature, but mine does not.

The highest current draw I have seen the my 60 amp DC-DC pull is 73 amps. My understanding is that you don't want your total alternator draw (the DC-DC and everything else) to be more than 80% of the alternator rating for extended periods.

[Treker20]

Originally Posted by reilym

Sorry, I just now saw this question. You are correct about VSS. I am using two of them (see this thread). One turns the DC-DC on through the D terminal with a delay after sensing > 13.2V and off when the voltage is below 12.8. The second one activates the L terminal on the DC-DC, which cuts the output (and input) in half when the input voltage is between 12.8 and 13.2. It activates instantly and turns L off after a delay once the voltage is > 13.2. In addition to the automatic switching provided by the VSS units, I can override everything from switches I installed in the cab, although I normally just let the VSSs do their thing. At the moment, I monitor the alternator temperature via an in-cab display and can either manually cut the current in half or turn the DC-DC off from the cab if it gets too hot. So far, I have not seen the alternator get over 190F, but I have not used the RV in extremely hot temps yet. Ideally, I would add the alternator temperature as another input to control the DC-DC directly, but that is a project for another day. I know there are alternators that have output attenuation based on temperature, but mine does not.

The highest current draw I have seen the my 60 amp DC-DC pull is 73 amps. My understanding is that you don't want your total alternator draw (the DC-DC and everything else) to be more than 80% of the alternator rating for extended periods.

Thanks Reily, I bought 2 of the VSSs but have not gotten to that part of the installation yet. In the next few days I will be mounting the B2B and then the VSSs.

I don't have a cut off switch in the cab. I may do that later. I do have a CB under the hood so could cut it off that way.

How do you monitor alternator temp?

I decided to go with the 40a B2b it may not be as much of an issue.

[booster]

Originally Posted by reilym

Sorry, I just now saw this question. You are correct about VSS. I am using two of them (see this thread). One turns the DC-DC on through the D terminal with a delay after sensing > 13.2V and off when the voltage is below 12.8. The second one activates the L terminal on the DC-DC, which cuts the output (and input) in half when the input voltage is between 12.8 and 13.2. It activates instantly and turns L off after a delay once the voltage is > 13.2. In addition to the automatic switching provided by the VSS units, I can override everything from switches I installed in the cab, although I normally just let the VSSs do their thing. At the moment, I monitor the alternator temperature via an in-cab display and can either manually cut the current in half or turn the DC-DC off from the cab if it gets too hot. So far, I have not seen the alternator get over 190F, but I have not used the RV in extremely hot temps yet. Ideally, I would add the alternator temperature as another input to control the DC-DC directly, but that is a project for another day. I know there are alternators that have output attenuation based on temperature, but mine does not.

The highest current draw I have seen the my 60 amp DC-DC pull is 73 amps. My understanding is that you don't want your total alternator draw (the DC-DC and everything else) to be more than 80% of the alternator rating for extended periods.

Depending on where the alternator is located in the engine compartment and the airflow it sees, and how hot you are OK with for alternator temperature, it is likely that using 80% of rated capacity will get it too hot. The alternator itself will lose max capacity the hotter it gets so you might only have 90% or less available of rated capacity when the alternator gets into the 220* degree range. You also need to consider van electrical needs which vary depending on many things and can range from 20 to probably 50 amps. Heater/AC fans, headlights, high power needs of the engine under heavy loads are the big users for many vehicles.


If it is hot out and the alternator does not get air that hasn't come through the radiator and AC condenser, it can see around 200* cooling air so that is a big deal for trying to cool the alternator.


Balmar uses about 225*F as the point where they turn down the output from alternator to protect it, and I think that is a good conservative temp to use, especially if you only have one alternator and need it to not fail prematurely. How are you sensing alternator temperature?


Going by alternator temperature is, by far IMO, the best way to control the alternator as the amps to temp correlation is just to variable with other things going on.


As a point of reference, on our Chevy Roadtrek with two parallel high performance alternators located in not very good locations for cool airflow, on a hot day, with moderate to heavy load, we will get them over 225*F at about 40% of rated output. Sprinters with a second alternator seem that is low and in clean cool air can get to 60-65% of rated on them based on the Balmar cycling net output information we have seen. Those alternators don't see any variable load from the van use so easy to tell how much power is actually being used. I don't recall seeing any information on actual temps for the Promasters with one or two alternators.

[reilym]

Originally Posted by Treker20

Thanks Reily, I bought 2 of the VSSs but have not gotten to that part of the installation yet. In the next few days I will be mounting the B2B and then the VSSs.

I don't have a cut off switch in the cab. I may do that later. I do have a CB under the hood so could cut it off that way.

How do you monitor alternator temp?

I decided to go with the 40a B2b it may not be as much of an issue.

Seems like the 40 amp is a safe choice. If you bought the DVB01 VSSs, check out the link above; somewhere in that thread I provided an English translation of the poorly written user guide that may prove helpful.

For the alternator temp, I bought a cheap digital thermometer with a 10 mm eyelet K-type thermocouple and bolted it to the alternator case behind one of the mounting bolts. It's undoubtedly only an approximation of the internal temperature and I have not yet calibrated it against readings that I get with an infrared thermometer. That was a lot of work and I can't say that I'd do it again knowing how difficult it was, but it's a cool blue LED read-out in the cab.

[Treker20]

Originally Posted by reilym

Sorry, I just now saw this question. You are correct about VSS. I am using two of them (see this thread). One turns the DC-DC on through the D terminal with a delay after sensing > 13.2V and off when the voltage is below 12.8. The second one activates the L terminal on the DC-DC, which cuts the output (and input) in half when the input voltage is between 12.8 and 13.2. It activates instantly and turns L off after a delay once the voltage is > 13.2. In addition to the automatic switching provided by the VSS units, I can override everything from switches I installed in the cab, although I normally just let the VSSs do their thing. At the moment, I monitor the alternator temperature via an in-cab display and can either manually cut the current in half or turn the DC-DC off from the cab if it gets too hot. So far, I have not seen the alternator get over 190F, but I have not used the RV in extremely hot temps yet. Ideally, I would add the alternator temperature as another input to control the DC-DC directly, but that is a project for another day. I know there are alternators that have output attenuation based on temperature, but mine does not.

The highest current draw I have seen the my 60 amp DC-DC pull is 73 amps. My understanding is that you don't want your total alternator draw (the DC-DC and everything else) to be more than 80% of the alternator rating for extended periods.

Mike, I like the idea of shutting down the Charger if alternator temps get to high. I did a little research and found this temp sensing relay. Do you think the sensor could be mounted on the alternator so you could get an accurate reading of temp? If so, mounting it under the hood would make installation easier, and not require a manual switch to turn off B2B. A concern I have would be about engine heat affecting life of relay. Somewhere in the info about the relay suggested keeping current draw to 8 amps at most to preserve life. Obviously amp draw is not a problem since it will be controlling the D+ circuit but engine heat may be. Info also said you could lengthen the wire on the temp sensor, but it did not say how long it could go. But doing so would make more installation issues.

protosupplies.com/product/w1290-temperature-controller-module/

[reilym]

Originally Posted by Treker20

Mike, I like the idea of shutting down the Charger if alternator temps get to high. I did a little research and found this temp sensing relay. Do you think the sensor could be mounted on the alternator so you could get an accurate reading of temp? If so, mounting it under the hood would make installation easier, and not require a manual switch to turn off B2B. A concern I have would be about engine heat affecting life of relay. Somewhere in the info about the relay suggested keeping current draw to 8 amps at most to preserve life. Obviously amp draw is not a problem since it will be controlling the D+ circuit but engine heat may be. Info also said you could lengthen the wire on the temp sensor, but it did not say how long it could go. But doing so would make more installation issues.

protosupplies.com/product/w1290-temperature-controller-module/

That link did not work for me. I should be able to use the thermocouple voltage to trigger shutting down the DC-DC if it rises above a certain threshold. Since the thermocouple and it's lead is designed for measuring head temperatures, the under hood temps should not be a problem. I have not seen the device you are talking about, but things are pretty tight in and around the alternator on the Promaster.