Battery to Converter wire upgrade

[TitanMike]

Originally Posted by babock

They are already monitoring the output. Do what they do on many alternators and have a sense terminal and just jump it to the output if you don't need it. Or use a switch like you said.

Sounds like this might possibly be a DIY modification if one could locate and isolate the monitoring point for the controller.

Your earlier comment reminded me of an old automotive battery/charging system test set that used to be sold. The company made a big deal out of the fact that all their voltage readings were taken using separate leads going all the way out to the jaws of the battery clamp. When loading the system the readings were of voltage present at the battery terminals, independent of any voltage reading at the equipment end of the heavy gauge wire that went to the Carbon Pile that provided the load. Made sense then but I haven't thought about it for 40 years.

[babock]

Originally Posted by TitanMike

Sounds like this might possibly be a DIY modification if one could locate and isolate the monitoring point for the controller.

Your earlier comment reminded me of an old automotive battery/charging system test set that used to be sold. The company made a big deal out of the fact that all their voltage readings were taken using separate leads going all the way out to the jaws of the battery clamp. When loading the system the readings were of voltage present at the battery terminals, independent of any voltage reading at the equipment end of the heavy gauge wire that went to the Carbon Pile that provided the load. Made sense then but I haven't thought about it for 40 years.

There are many solar controllers out there that do remote sensing. Just haven't seen any converters. I am sure there are some somewhere.

Are you measuring your charge current with a battery monitor? If you are getting a 1.38% drop at 17A, you are pretty good. Even at 34A, you would be less than 3%. Unless you get AGM batteries, your current batteries aren't even going to accept much more than that.

[TitanMike]

Originally Posted by babock

There are many solar controllers out there that do remote sensing. Just haven't seen any converters. I am sure there are some somewhere.

Are you measuring your charge current with a battery monitor? If you are getting a 1.38% drop at 17A, you are pretty good. Even at 34A, you would be less than 3%. Unless you get AGM batteries, your current batteries aren't even going to accept much more than that.

Yes. I have the Victron BMV 702. With the batteries slightly discharged, and I flip the switch on for the converter, I see charging current rise to 25 amp or more initially. It then rapidly drops as the battery SOC increases.

The real test is going to be when the batteries are more fully discharged and it takes a couple of hours of charging before the current flow tapers.

Since most of my charging will be done with a generator/inverter while boondocking I expect this upgrade to greatly reduce run time on the generator/inverter.

I was rather pleased that with EVERYTHING running, the current draw was only 17 amp. I doubt that I will ever see that situation while camping.

Maybe a light or two in the evening, the hood fan while cooking, the fantastic fan when showering, and TV in the evening but not all at once. With 260 amp hour battery capacity I should be able to make it a couple days before having to run the generator. Plan on testing this theory right after the 4th. Just have to wait until those who are still working go home and leave me some room in the campground. Next trip will be to a NF camp

[TitanMike]

Originally Posted by babock

There are many solar controllers out there that do remote sensing. Just haven't seen any converters. I am sure there are some somewhere.

Are you measuring your charge current with a battery monitor? If you are getting a 1.38% drop at 17A, you are pretty good. Even at 34A, you would be less than 3%. Unless you get AGM batteries, your current batteries aren't even going to accept much more than that.

Yes. I have the Victron BMV 702. With the batteries slightly discharged, and I flip the switch on for the converter, I see charging current rise to 25 amp or more initially. It then rapidly drops as the battery SOC increases.

The real test is going to be when the batteries are more fully discharged and it takes a couple of hours of charging before the current flow tapers.

Since most of my charging will be done with a generator/inverter while boondocking I expect this upgrade to greatly reduce run time on the generator/inverter.

I was rather pleased that with EVERYTHING running, the current draw was only 17 amp. I doubt that I will ever see that situation while camping.

Maybe a light or two in the evening, the hood fan while cooking, the fantastic fan when showering, and TV in the evening but not all at once. With 260 amp hour battery capacity I should be able to make it a couple days before having to run the generator. Plan on testing this theory right after the 4th. Just have to wait until those who are still working go home and leave me some room in the campground. Next trip will be to a NF campground with nothing but the site with picnic table and pit toilet somewhere in the campground. Not even potable water although it's located on a river. (The river should mask what little noise my inverter generator makes).

[Jay2504]

I did a similar upgrade to my stock WFCO converter. Ground cable to the frame from the batteries was all ready 4/0. I added extra wire to the converter to frame connections and added extra wire (forgot whether it was 10 or 8) to the existing wire on the positive side. Bout a 25 or so foot run. Made a real difference in battery charging. I just used what I had laying around at the time. Jay.

[TitanMike]

Got all the wiring in place and decided to run a test. Won't be camping for another week so I just turned off the converter for 3 days. Turned on lights and let Fantastic Fan run on #3 continuously (Trailer could use a good airing out anyway).

After my Victron meter showed a 65 ah discharge (after 3 full days) I turned off the lights and fan then turned the converter on. It jumped to a 56 amp output, dropped to a fairly steady 50 amp rate, and slowly tapered over the next hour to ~25 amp.

In the next 2 hours the charge current dropped to less than 3 amp and at the 3 hour mark the batteries were drawing less than 1 amp from the charger and bank showed 100% state of charge.

12 hours later the Victron shows 13.65 v and current of .1 amp so it's just sitting there in absorption mode, waiting to switch to storage mode.


Indications are that whenever I need to start the generator to recharge batteries I'll be able to shut it off far sooner than if I had left the OEM wiring in place. I guess the factory figures that all battery charging will occur when the owners park for the night with hookups and charging time isn't all that big a deal.

[babock]

Sounds good

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