Upgrading Dodge Alternator

[wincrasher]

With the BMK installed, I can get a good look now on my house battery charging.

I'm seeing 125-135 amps from my Magnum 2812. I get around 10-12 amps from my solar. At idle, I see 32-35 amps from the alternator, and it can jump to 37-40 amps reving the engine.

So I'm considering the feasibility of upgrading the alternator. Nations has one that will fit my van - it says it's good for 200 at idle and 270 peak. Of course I don't need anywhere near that - I'd be quite happy 125-150 amps.

Here's a link to the alternator: https://www.nationsstarteralternator...3824-270xp.htm

Below I've attached my electrical drawings. Not much to work with. So I need some advice as to how bad a project this would be. If I read the drawings correctly, there is only #6 wire from the alternator to the isolator. I expect this may need to be upgraded. Also, which of these circuit breakers? Would I also need to upgrade the isolator?

Any input appreciated! I'm only looking to upgrade the primary alternator. Think adding a second alternator is out of the question for this old van, plus I'm not keen on the complexity of doing such a project.

[BBQ]

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Holy smoke $640 for the alternator

[wincrasher]

Originally Posted by BBQ

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Holy smoke $640 for the alternator

I know! There are $200 ones on ebay, but you don't really know what you are getting. Not terribly worried about costs, more worried about starting a fire.

[wincrasher]

Some pics of what I have. Does look like the drawings, thankfully.

[markopolo]

That's an impressive set of documentation of the system. The radio relay and emergency start features are nice to have. Your setup appears to be like page 5 for the Norcold fridge. (not page 4)

I think that the simplest way would be to leave everything in place as is as you replace the alternator.
Then, a new heavy gauge wire from the new alternator to a new latching relay separator then on to the new house batteries would be needed to handle the higher current. The new stuff would be in parallel to the untouched old setup. I'd fuse both ends of the new wire (relay to house bank).
You'd have to confirm that the ground wiring is adequately rated for the task and upgrade if necessary.

I'm sure this idea is far from ideal or perfect so comments pointing out any negative consequences are needed and welcomed.

[prfleming]

My idea is similar, leave stock system in place, disconnect and lay in new wiring. You will need to increase wire gauge.

I would go with a smart combiner relay like

https://www.waytekwire.com/item/7705...solator-200A-/

I have used this with good results when my son added a 2nd battery to his Lincoln for his subwoofer amp. The spec sheets include wiring examples. The rating is 200 amps continuous, can handle more for short periods. Also has emergency start assist feature.

[booster]

We did run a parallel system, old and new, in our Roadtrek for a while, like Marko and prfleming suggested. We did not have quite as much alternator as Wincrasher is looking at, but it was a 250 amp DC Power unit, so much the same.

Ours was a second #4 wire in parallel with the original #4 which gave us just enough capacity at 160 amps using the Blue Sea Circuit Wizard. That allowed us to leave the original both end Roadtrek breakers on each end of their wire and add to more of our own. For short periods, you should be able to go a bit higher on amps, IIRC, and we know the Nations alternator will only average about 165 amps output over time, so probably just fine as the van will put about 15 amps off it too.

I agree that just adding another cable and a separator would be the quickest, easiest, cheapest, and totally adequate way to go.

As mentioned, the ground path is often ignored, and shouldn't be. I added a 1/0 engine ground strap to ours as the original was very small. I also bonded the body to the frame with a piece of larger cable, as the bodies can be isolated on rubber with only a small jumper.

[JohnnyFry]

My only concern here is that you will overload the isolator diodes with the new alternator. You could get around this problem by converting to a separator set up pretty easily. I have not seen too many isolators with greater than 150 amp alternator capacity.

[BBQ]

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Can't wait to hear the end results;
I have always thought the 2nd alternator is not the perfect solution,
I too, believe all you need is a bigger alternator. I hope you can prove the idea works.

[prfleming]

It will cost more, but I would recommend getting the Nations/Balmar controller combo. This is on our Roadtrek and works great, gives you multi-stage charging, voltage sense, and adjustable settings.

[markopolo]

The old 1602 isolator happens to have a 160A rating.

I don't think it would be the chosen path for most of the current from the new alternator to the new house batteries if left in parallel new separator/relay/combiner with new heavy gauge wire.

I left the old isolator in place when I made a lot of changes to my van. I consider it to be a backup system. I can get approx 90A for short duration house loads out of the the old 124A alternator and remain at a charging voltage (no draw from batteries) because of the new heavier gauge wire and new separator/relay/combiner thingy.

[booster]

Originally Posted by prfleming

It will cost more, but I would recommend getting the Nations/Balmar controller combo. This is on our Roadtrek and works great, gives you multi-stage charging, voltage sense, and adjustable settings.

I have mixed feeling about using the Balmar regulator, especially when it will be running non matched batteries and chassis power used. They are also pretty expensive. All the stuff running and mismatched batteries will almost certainly confuse the algorithm in the Balmar.

When we ran a single big DC Power alternator, we used the internal, Denso style, regulator instead of going with a separate one. The Denso has 3 stages of voltage reduction and also built in temp protection, so it is much better than your normal off the shelf regulator. It appeared to do about as well at guessing the charging needed as the Balmars I have seen, but that mostly means both were not very good at getting full without overcharging.

As long as you have a battery monitor running, you will be able to tell if the batteries are full or getting overcharged, as well as if they wound up on float too soon and won't get full. It is easy to address the overcharging issue by using a separator with a remote disconnect switch like Blue Sea makes. Watch the monitor, and turn off the charging to the coach when they get full. The good is if you have the alternator running the chassis also, like is being discussed, you can shut off the engine charging with the separator with no chance of damage to the alternator from spikes because you still have a battery in the system. This is the way our dual alternator system works, as both alternators run both the van and the coach, and is also how we had the single large one setup. It worked nicely for us.

I think for this setup, using the internal regulator would be OK, and the money saved could be used to get the switchable separator.

[wincrasher]

Thanks for all the comments. Trying to digest what some of you are saying. I think the internal regulator would probably be OK. Don't think I need three stage charging since I using lithium batteries.

I made this sketch showing what I think Marko is saying. Not sure where the other feed off a parallel isolator would go.

[markopolo]

That's the idea. I wouldn't use a diode based isolator though. A separator / relay / combiner type device would allow full voltage through.

2/0 welding cable shouldn't be too expensive and is easy to work with because it is so flexible. I made some cables using it recently and was able to solder the lugs after crimping them. The sheathing seems very tolerant to heat and didn't shrink much at all if any.

I'd probably fuse both ends of the new cable between the new separator and the lithium battery bank but am not sure if two would actually be needed.

[booster]

Originally Posted by markopolo

That's the idea. I wouldn't use a diode based isolator though. A separator / relay / combiner type device would allow full voltage through.

2/0 welding cable shouldn't be too expensive and is easy to work with because it is so flexible. I made some cables using it recently and was able to solder the lugs after crimping them. The sheathing seems very tolerant to heat and didn't shrink much at all if any.

I'd probably fuse both ends of the new cable between the new separator and the lithium battery bank but am not sure if two would actually be needed.

I agree, especially on the separator instead of isolator. Also if the lithium battery BMS doesn't fully disconnect charging when full, the separator mentioned earlier with a remote switch might be a good add on.

The "normal" rules would say you would fuse both ends of the cable from the separator to the batteries. It is usually described as fusing all ends that contain a "power source" to the wire. That would be an alternator, battery, generator, shore power, solar, hamster on a wheel, or anything else that could provide electrical power.

[wincrasher]

Anyone suggest a specific separator or isolator device that I should use?

Are you suggesting something like this? https://www.amazon.com/Blue-Sea-Syst...%2Bremote&th=1

I like the idea of just remotely shutting it off when the amps drop to zero.

Are there not both a positive and negative terminal on an alternator? Does the negative just go to ground?

[booster]

I like the Blue Sea ones, which are very nice and come with their own mated remote switch.

We use a full manual control, so no automatic connecting when it sees charging voltage. We like that because the solar would connect it otherwise when we didn't want it to if we didn't have it shut off of automatic. Those are the 7700 model.

They also make the same thing in a combination automatic charge control relay that will connect automatically, but can be overridden with the switch. They also work very well, if you want to have the automatic part. I think that would be a 7622 model IIRC.

No negative on the alternators, they ground through the alternator frame to the engine, to the the frame of the van.

[tgregg]

Originally Posted by wincrasher

Anyone suggest a specific separator or isolator device that I should use?

I like the idea of just remotely shutting it off when the amps drop to zero.

I looked for an automatic separator that would work with LiFePo4 voltages and couldn't find one.

All of the ones I looked at would combine the house and vehicle batteries when it sensed the alternator was charging, but, because the typical resting voltage of LiFePo4 batteries is over 13 volts the separator would sense the house batteries as being charged and combine the house and vehicle batteries even though no charger was present and the Li batteries would essentially discharge into the vehicle battery.

I think you need a simple solenoid capable of handling the current and convenient switch to trigger the solenoid to combine or separate the batteries.

I added a small relay to my existing separator that was triggered by the ignition being on and the engine running to cause the separator to combine the house and engine batteries. I also have a switch like you mention that allows me to turn off separator when the battery monitor indicates the current has approached zero.

I believe you had Li batteries in your WGO which had an ignition controlled separator relay. Perhaps you could duplicate that in your latest RV?

[wincrasher]

Actually, by leaving the existing separator in line, I don't quite understand why I need another parallel separator to run from the alternator to the battery bank. What is the "separation" really doing? As I showed in the sketch - one terminal runs to the house batteries, the other goes no-where. So what does it do?

Or would this be a better choice? Just a remote battery switch? https://www.bluesea.com/products/770..._-_12V_DC_500A

Or are we talking more like this:

[booster]

I was just sketching a reply when you posted, very close to same, but slightly different.