DC-to-DC + Isolator

[booster]

Originally Posted by Rlum

I know lots of folks have DC to DC chargers installed to preserve and increase life of alternators. How about an easier/simpler solution. Use an XP270 or XP370 alternator? Aside from the cost compared to the DC to DC chargers, what other issues do you see installing a different alternator?

If you are installing it as a standalone no issue, but there may be issues with factory electronics if trying to tie it into the van to replace the stock unit. Our 07 Chevy was on of the last I know of that you could just plop on in without some sort of interface adapter or such, IIRC.


We had an XP250 in place of the stock alternator in the Chevy and the 4 AGMs from 50% down got it up over 250*F. Unknown amps as I didn't have the instrumentation in place way back then. That is what convinced me to add a second alternator in parallel, with both off a remote regulator. We now have an XP250 and an XP280 in place.


If you look at the charge curve for the XP370, it really loses the low rpm performance to increase the high end, or at least that is what the curves showed back then, so it wouldn't be as useful in and RV that may need to charge at idle or slow speeds.

[avanti]

Originally Posted by Rlum

I know lots of folks have DC to DC chargers installed to preserve and increase life of alternators. How about an easier/simpler solution. Use an XP270 or XP370 alternator? Aside from the cost compared to the DC to DC chargers, what other issues do you see installing a different alternator?

Well, it's complicated.
With respect to the issue I discussed in message #37 above, a more powerful alternator just makes matters worse. I suppose if you are willing to size the rest of the system for the max output of the alternator (including wires and fuses), you could end up with a safe system, but I am not sure that would be the cheapest approach.

Also, it depends on what kind of van you are talking about. Most modern vehicles have LIN-controlled alternators, rather than self-regulating ones. This has been true for Sprinters, for example, since the first NCV3s. You can get heavy-duty LIN-based alternators that may work, but you don't know what kind of assumptions the ECU is making. For this reason, most OEMs say you can only use the specified part. Of course, the worst case are new vehicles that use "smart" electrical systems, which have their own complexities. They will always have a maximum takeoff spec, which often bears little connection with the raw alternator capacity. As I said, Sprinters are limited to 40A, which must be enforced by a B2B.

With older rigs, things are more loosy-goosy, but adding lithium to the mix immediately creates the possibility of large currents under some conditions. As I said, high currents call for real engineering.

[Rlum]

Originally Posted by booster

If you are installing it as a standalone no issue, but there may be issues with factory electronics if trying to tie it into the van to replace the stock unit. Our 07 Chevy was on of the last I know of that you could just plop on in without some sort of interface adapter or such, IIRC.


We had an XP250 in place of the stock alternator in the Chevy and the 4 AGMs from 50% down got it up over 250*F. Unknown amps as I didn't have the instrumentation in place way back then. That is what convinced me to add a second alternator in parallel, with both off a remote regulator. We now have an XP250 and an XP280 in place.


If you look at the charge curve for the XP370, it really loses the low rpm performance to increase the high end, or at least that is what the curves showed back then, so it wouldn't be as useful in and RV that may need to charge at idle or slow speeds.

I have 2016 PW Lexor. It came with 200ah lithiums. Stock alternator(180amp?). Standard isolator. Increased the battery bank to 800 lithiums. Mostly use genny to charge battery bank with Victron 3000/12 inverter converter unit while camping. Puts out about 80amp/hr. Not on road driving too much. Mostly arrive at camp and leave after 4 days. I see on my Victron 712 BMS, when driving down road, alternator is putting in 100amps into the bank until fully charged. Usually less than 2 hours. I do not know if this is an issue for the alternator. Do not know alternator temp or how many amps it is putting out. Is there is simple way to get this data?

[avanti]

Originally Posted by Rlum

I have 2016 PW Lexor. It came with 200ah lithiums. Stock alternator(180amp?). Standard isolator. Increased the battery bank to 800 lithiums. Mostly use genny to charge battery bank with Victron 3000/12 inverter converter unit while camping. Puts out about 80amp/hr. Not on road driving too much. Mostly arrive at camp and leave after 4 days. I see on my Victron 712 BMS, when driving down road, alternator is putting in 100amps into the bank until fully charged. Usually less than 2 hours. I do not know if this is an issue for the alternator. Do not know alternator temp or how many amps it is putting out. Is there is simple way to get this data?

What sized wires go between the alternator and the battery? How are they fused?

[Rlum]

Originally Posted by avanti

What sized wires go between the alternator and the battery? How are they fused?

I believe it is #2. Sorry but do not know the fuse. I know there is 100amp fuse near the hose battery.

There were installed by PW. I have only changed out a malfunctioning isolator.

Thanks

[reilym]

Originally Posted by Rlum

I believe it is #2. Sorry but do not know the fuse. I know there is 100amp fuse near the hose battery.

There were installed by PW. I have only changed out a malfunctioning isolator.

Thanks

My 2016 PW has two #2 wires going from separator to coach, each with a 150 amp fuse. I believe the fuse near the house battery is also 150 amps. The stock alternator is 220 amps.

[booster]

If you get an inexpensive infrared thermometer (Harbor Freight ones work OK, I have one) and an inexpensive DC clamp on ammeter (don't have an inexpensive one, but others certainly may have them) you would be able to get pretty good information.


The problem with both is that you have to be parked to use them with the hood open. Best to drive for a while with the batteries charging from a deep discharge, stop, open the hood and immediately check the alternator temp at the hottest place which is usually the laminated windings or the diodes. Then put the ammeter on the wire from the alternator to the separator but make sure no other wires go into that wire before the alternator. Rev the engine to highway until you see maximum amps on the meter. That will be your alternator output at the amps you just read.


Repeat the amp test with AC on and fan on high as that will probably add 20 more amps.

[Rlum]

Originally Posted by booster

If you get an inexpensive infrared thermometer (Harbor Freight ones work OK, I have one) and an inexpensive DC clamp on ammeter (don't have an inexpensive one, but others certainly may have them) you would be able to get pretty good information.


The problem with both is that you have to be parked to use them with the hood open. Best to drive for a while with the batteries charging from a deep discharge, stop, open the hood and immediately check the alternator temp at the hottest place which is usually the laminated windings or the diodes. Then put the ammeter on the wire from the alternator to the separator but make sure no other wires go into that wire before the alternator. Rev the engine to highway until you see maximum amps on the meter. That will be your alternator output at the amps you just read.


Repeat the amp test with AC on and fan on high as that will probably add 20 more amps.

Thanks!

All this trouble with alternator charging, overheating, over taxing ability to charge lithiums in deep discharge state.

Have you ever considered just charging from onboard genny when driving? I have done this when I did get enough exercise time in. Just fire up genny and charge my lithiums?

[Rlum]

Originally Posted by reilym

My 2016 PW has two #2 wires going from separator to coach, each with a 150 amp fuse. I believe the fuse near the house battery is also 150 amps. The stock alternator is 220 amps.

I thought the stock alternator was 180amp. 220 amp alternator was the upgrade. Interesting about PW installing two #2 wires from separator to coach? Separate lines separate fuses? Does that mean the PW did not think the alternator would be overtaxed when charging lithiums?

Did you say when you got the PW. The circuit breakers(fuses) were popped and you had to reset them?

[reilym]

Originally Posted by Rlum

I thought the stock alternator was 180amp. 220 amp alternator was the upgrade. Interesting about PW installing two #2 wires from separator to coach? Separate lines separate fuses? Does that mean the PW did not think the alternator would be overtaxed when charging lithiums?

Did you say when you got the PW. The circuit breakers(fuses) were popped and you had to reset them?

Mine has two fat wires with 150 amp fuses, not breakers. I had to unwrap and replace the fuses and the separator before I could charge from the alternator. As I said in my previous post, I think PW did this in 2016 when they transitioned from AGM to Lithium. That is speculation based on looking at underhood photos of earlier model years. I'd be curious to know if your Lexor does not have 2 cables going back to the coach batteries.

According to the PW brochure, the Promaster RVs come with a 220 amp alternator.

[Rlum]

Originally Posted by reilym

Mine has two fat wires with 150 amp fuses, not breakers. I had to unwrap and replace the fuses and the separator before I could charge from the alternator. As I said in my previous post, I think PW did this in 2016 when they transitioned from AGM to Lithium. That is speculation based on looking at underhood photos of earlier model years. I'd be curious to know if your Lexor does not have 2 cables going back to the coach batteries.

According to the PW brochure, the Promaster RVs come with a 220 amp alternator.

Interesting. 2016 was transition year for PW and lithiums. PW was probably changing manufacturing constantly. I do not know if I have two cables feeding the battery bank? My van is in storage. Will check next time out there. I do not have fuses for sure. They are push button, lever breakers. Also I do not have the inframous "Red Key" People on FB always ask about this key for winter storage. Some FB members have stated they have 180amp alternator in their 2016? It seems PW would have installed 220amp alternator from Ram? My lithiums came in a metal box under the trunk behind genny. Spare tire was in the trunk under sofa bed.

[reilym]

Originally Posted by Rlum

Interesting. 2016 was transition year for PW and lithiums. PW was probably changing manufacturing constantly. I do not know if I have two cables feeding the battery bank? My van is in storage. Will check next time out there. I do not have fuses for sure. They are push button, lever breakers. Also I do not have the inframous "Red Key" People on FB always ask about this key for winter storage. Some FB members have stated they have 180amp alternator in their 2016? It seems PW would have installed 220amp alternator from Ram? My lithiums came in a metal box under the trunk behind genny. Spare tire was in the trunk under sofa bed.

I have push button breakers under the DS ottoman also. The fuses are in the two cables about a foot or so from where they attach to the separator under the hood. Look for a bulge in the cable. There's a fuse in there. The red key is for preventing alternator or solar charging of the batteries for servicing or driving in cold weather. It is prominent in the owners manual on inside the ottoman access door. The external box for storing the batteries was also a hold-over from the AGM era. In 2017, they moved the batteries into a box under the seat to keep the lithiums out of the cold weather. I like the extra storage, but need to make sure to keep in eye on battery temperatures when it's cold outside. Not a problem in So Cal, I suppose.

[avanti]

It would be interesting to see how many amps the batteries would draw if they were near-fully-discharged. I could imagine it being enough to blow those fuses.

[booster]

Originally Posted by reilym

As I said in my previous post, I think PW did this in 2016 when they transitioned from AGM to Lithium. That is speculation based on looking at underhood photos of earlier model years.

I think they were going lithium sooner than that. We saw a Lexor on the Chevy chassis at the Minneapolis RV show in 2014, IIRC, which I think was about the last year for Chevy with Pleasure-way.


It had two 100ah lithium models under the bed, crosswize up by the bolsters.



The sales guys and factory reps knew nothing about lithium then. They claimed good in all temps and the van did actually use all the standard AGM electrical parts so the factory didn't know much more, I think.

[Rlum]

Originally Posted by avanti

It would be interesting to see how many amps the batteries would draw if they were near-fully-discharged. I could imagine it being enough to blow those fuses.

Your are probably right. Interesting since generally, I do not run my lithiums down past 30 percent. If I need air conditioning for extended periods of time, I will run generator.

Most I have ever seen on Victron 712 when driving was 130 amps. I believe it was for 1 hour maybe. It is common for me to see 100amps for maybe an hour and before batteries are fully charged again.

[Rlum]

Originally Posted by reilym

I have push button breakers under the DS ottoman also. The fuses are in the two cables about a foot or so from where they attach to the separator under the hood. Look for a bulge in the cable. There's a fuse in there. The red key is for preventing alternator or solar charging of the batteries for servicing or driving in cold weather. It is prominent in the owners manual on inside the ottoman access door. The external box for storing the batteries was also a hold-over from the AGM era. In 2017, they moved the batteries into a box under the seat to keep the lithiums out of the cold weather. I like the extra storage, but need to make sure to keep in eye on battery temperatures when it's cold outside. Not a problem in So Cal, I suppose.

Will take a look. Van is in storage for now so not at my home. Two cables to charge battery bank with 150 amp fuses seems like asking for serious heating issues with alternator.

[reilym]

Originally Posted by booster

I think they were going lithium sooner than that. We saw a Lexor on the Chevy chassis at the Minneapolis RV show in 2014, IIRC, which I think was about the last year for Chevy with Pleasure-way.


It had two 100ah lithium models under the bed, crosswize up by the bolsters.



The sales guys and factory reps knew nothing about lithium then. They claimed good in all temps and the van did actually use all the standard AGM electrical parts so the factory didn't know much more, I think.

At least for the Lexor (on the Promaster platform), 2016 was the first time lithium batteries were standard. The following year, they moved them from under the coach to inside under the seat.

[reilym]

Originally Posted by Rlum

Your are probably right. Interesting since generally, I do not run my lithiums down past 30 percent. If I need air conditioning for extended periods of time, I will run generator.

Most I have ever seen on Victron 712 when driving was 130 amps. I believe it was for 1 hour maybe. It is common for me to see 100amps for maybe an hour and before batteries are fully charged again.

Before I installed the DC-DC charger, I was seeing 150 amps on discharged coach batteries, so 75 amps thorough each cable. The person I bought the van from had no way to monitor alternator charge current. I suspect that whatever event caused the fuses to blow (like a short circuit) was either conceited by him or it happened during a service visit and he was unaware of it. The terminals on the sure power separator are very exposed under the hood on that model, so I could imagine an accidental short could have occurred during a routine service visit. He did tell me that he used LP to run the fridge while driving (not a good idea) to avoid depleting the battery. I discovered the dysfunctional alternator charging the hard way while on the drive back to Michigan from Phoenix where we picked it up. I replaced the faulty separator and blown fuses after we got home and I had time to trouble shoot. When I installed the DC-DC charger, I replaced the separator with a manual on/off switch which has the terminals much more out of the way. So far, I am very happy with my setup.

[Rlum]

Originally Posted by reilym

Before I installed the DC-DC charger, I was seeing 150 amps on discharged coach batteries, so 75 amps thorough each cable. The person I bought the van from had no way to monitor alternator charge current. I suspect that whatever event caused the fuses to blow (like a short circuit) was either conceited by him or it happened during a service visit and he was unaware of it. The terminals on the sure power separator are very exposed under the hood on that model, so I could imagine an accidental short could have occurred during a routine service visit. He did tell me that he used LP to run the fridge while driving (not a good idea) to avoid depleting the battery. I discovered the dysfunctional alternator charging the hard way while on the drive back to Michigan from Phoenix where we picked it up. I replaced the faulty separator and blown fuses after we got home and I had time to trouble shoot. When I installed the DC-DC charger, I replaced the separator with a manual on/off switch which has the terminals much more out of the way. So far, I am very happy with my setup.

Thanks for update. Just checked my connections. You are correct. There are two cables(2.0) from the isolated. Fused but I did not remove the covering so do not know what fuse size. Interesting way to wire. i guess maybe to difficult to run larger gauge wire and easier to run 2 separated smaller gauge. Net effect is same?

I replaced my separator about 2 yrs ago. Placed a marine on/off switch to the negative(small wire on back). I turn it off each time, I put into storage. Then check my Victron 712 BMS. Make sure there is no loss of power or parasitic drains. I have a Victron solar controller to check if am getting any amps from it. Generally it never rains in Southern California. In outside storage batteries stay at around 13.8 to 14.2 with just solar. Victron solar controller is great. Bluetooth enable so I can turn it off. No need for red key!

[Rlum]

Originally Posted by reilym

Before I installed the DC-DC charger, I was seeing 150 amps on discharged coach batteries, so 75 amps thorough each cable. The person I bought the van from had no way to monitor alternator charge current. I suspect that whatever event caused the fuses to blow (like a short circuit) was either conceited by him or it happened during a service visit and he was unaware of it. The terminals on the sure power separator are very exposed under the hood on that model, so I could imagine an accidental short could have occurred during a routine service visit. He did tell me that he used LP to run the fridge while driving (not a good idea) to avoid depleting the battery. I discovered the dysfunctional alternator charging the hard way while on the drive back to Michigan from Phoenix where we picked it up. I replaced the faulty separator and blown fuses after we got home and I had time to trouble shoot. When I installed the DC-DC charger, I replaced the separator with a manual on/off switch which has the terminals much more out of the way. So far, I am very happy with my setup.

Would you consider leaving wiring without changes? Change out the alternator to a 270 amp or 370amp? Do you think this would work for large battery bank without overloading the wires/fuses?