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Old 10-20-2021, 09:08 AM   #15
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KanzKran:

It is the Balmar regulator that is saving the Nations alternator from burning up, not the alternator itself. Balmar has two things that do this:

You can set the maximum current supplied from the Nations alternator with the Balmar. You can also set up an alternator temperature probe which cuts back charging current from the alternator when it gets too hot.

I have used the latter feature on cruising boats and it works well. If the outside weather is cool then the alternator is not throttled back because it has sufficient cooling. But on a hot day it cuts back to protect the alternator.

Unfortunately using a Balmar external regulator does require the coach's alternator to be an externally regulated one. Most, maybe almost all are not. Your second Nations alternator obviously is and it works well with the Balmar regulator..

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Old 10-20-2021, 01:29 PM   #16
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Originally Posted by Kid Gloves View Post
The DC/DC charger allows 30 amps of the alternators output to charge the house batteries. The alternator will still be capable of outputting additional current to other loads.
Yes, but is your lithium battery output now also limited in some way?

I know you can no longer bridge the two batteries together to start your RV...
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Old 10-20-2021, 02:12 PM   #17
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Yes, but is your lithium battery output now also limited in some way?

I know you can no longer bridge the two batteries together to start your RV...
No. The lithium battery output goes to the inverter. The only thing that is being limited is the amount of charging from the alternator to the battery.
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Old 10-20-2021, 11:27 PM   #18
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.....

I know you can no longer bridge the two batteries together to start your RV...

After I remove the existing battery isolator and solenoid that formed the house to starter battery boost, that function does go away. However, since I still want that function, I'll add a new solenoid connected to existing dash switch to allow the two battery banks to be tied for engine starting if needed. Since this function would only be for a few moments until the engine starts (alternator starts at same time) I do not think there would be any strain on the alternator.
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Old 10-21-2021, 07:50 AM   #19
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I know you can no longer bridge the two batteries together to start your RV...
I decided that the benefit of DC to DC charger was worth the risk of not being able to use the coach battery to start the engine. So I bought one of those small jump start battery packs and just keep it in the coach. It comes in handy for other things, too. Last week I loaned it to the trailer parked next to us when their tow vehicle wouldn't start.
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Old 10-21-2021, 08:11 AM   #20
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I decided that the benefit of DC to DC charger was worth the risk of not being able to use the coach battery to start the engine. So I bought one of those small jump start battery packs and just keep it in the coach.
I carry a set of heavy gauge jumper cables that are long enough to jump-start the chassis battery with the house batteries. With our rig, it's not that far of a distance. Having the batteries favoring the same side of the rig also shortens the length.
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Old 10-21-2021, 04:06 PM   #21
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I carry a set of heavy gauge jumper cables that are long enough to jump-start the chassis battery with the house batteries. With our rig, it's not that far of a distance. Having the batteries favoring the same side of the rig also shortens the length.
Ron, your recommendation above raises a question - won't the boost switch on the dash work? i.e. Won't pressing and holding the boost switch while turning the ignition key when the chassis battery is low cause the coach batteries to boost the chassis battery so as to start the engine?

I'm going from memory, but I think I had to do this once years age and it worked great to start the engine. Isn't this what the boost switch is for?
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Old 10-21-2021, 05:39 PM   #22
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Ron, your recommendation above raises a question - won't the boost switch on the dash work? i.e. Won't pressing and holding the boost switch while turning the ignition key when the chassis battery is low cause the coach batteries to boost the chassis battery so as to start the engine?

I'm going from memory, but I think I had to do this once years age and it worked great to start the engine. Isn't this what the boost switch is for?

Yes, that's what the switch is for.
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Old 10-21-2021, 05:48 PM   #23
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Ron, your recommendation above raises a question - won't the boost switch on the dash work? i.e. Won't pressing and holding the boost switch while turning the ignition key when the chassis battery is low cause the coach batteries to boost the chassis battery so as to start the engine?

I'm going from memory, but I think I had to do this once years age and it worked great to start the engine. Isn't this what the boost switch is for?
Yes, that's how it comes wired from the factory. But if you put a DC to DC charger between the solenoid and the coach batteries (as I did) then it won't work that way anymore. The boost switch will still close the connection, but that only connects to the DC to DC charger which won't provide any power to start the engine. That's why I carry the jump start battery instead.
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Old 10-21-2021, 11:06 PM   #24
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The preceding discussions/descriptions of DC-to-DC battery charging have me scratching my head.(?)

Why does connecting the chassis battery terminals to a DC-to-DC charger, which in turn is connected to the coach battery(ies)'s terminals ... which I assume is done in an electrical way such as to allow only current flow from the chassis battery to the coach battery(ies) when that setup is needed ... negate the "other" direct path that the boost switch and solenoid momentarily establishes so as to allow more current flow into the engine starter for a few seconds?

I guess I'm missing something as to why the two functions can't be separate from each other.
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Old 10-22-2021, 03:47 AM   #25
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In a MH (2006 Ford E450 Super duty, V10) with a stock alternator and three Battle Born lithium batteries how much of chance is there of alternator damage (diode burnout) from recharging the lithium batteries, especially at low idle speeds? The RV has a factory start boost circuit, house batteries to engine. I believe this same cable (a 2 ga +/- cable) is used to recharge the house batteries when the engine is running.

Another way of asking, if and when you converted to lithium batteries and have a battery boost feature, did you do anything to deal with potential alternator damage?

I did this battery upgrade in mid trip and was not thinking about the alternator issue at the time. Since we'll be on the road for another month+ and 1,000 miles or so, I'd like to defer dealing with the alternator issue until we get home and not try to do it as a filed modification, but not sure of the potential risks I'm running by deferring this work.

What are the real world experiences?
Call Battle Born. Batteries too expensive and they are the ones you have the warranty with.
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Old 10-22-2021, 07:58 AM   #26
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Why does connecting the chassis battery terminals to a DC-to-DC charger, which in turn is connected to the coach battery(ies)'s terminals ... which I assume is done in an electrical way such as to allow only current flow from the chassis battery to the coach battery(ies) when that setup is needed ... negate the "other" direct path that the boost switch and solenoid momentarily establishes so as to allow more current flow into the engine starter for a few seconds?

I guess I'm missing something as to why the two functions can't be separate from each other.
Well, it can be wired so that the two functions are separate by wiring another wire from the boost solenoid to the coach battery. That's what others have suggested above. Then you need a switch that chooses which wire to use so that the charge current doesn't just bypass the DC to DC charger and take the direct path. But I didn't want to run another large gauge wire from the solenoid to battery so took the route that I suggested. Either way will work. My solution is less elegant but also less work.
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Old 10-22-2021, 08:09 AM   #27
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Originally Posted by rarebear.nm View Post
After I remove the existing battery isolator and solenoid that formed the house to starter battery boost, that function does go away. However, since I still want that function, I'll add a new solenoid connected to existing dash switch to allow the two battery banks to be tied for engine starting if needed. Since this function would only be for a few moments until the engine starts (alternator starts at same time) I do not think there would be any strain on the alternator.
Fred, Not sure about your rig but many (ours included) came from the factory with a Trombetta (Selenoid) that was activated to keep the chassis batteries charged while parked and also was the mechanism to bridge the batteries for starting when needed.

In our case when we upgraded to Lithium we simply disconnected the charging function and it is now limited to the bridging function for starting.....sounds like what you will accomplish by adding a solenoid if your coach did not come with one previously
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Old 10-22-2021, 08:25 AM   #28
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I would guess that the cables to/from the solenoid for battery combining are pretty heavy, so I would add lighter cables to bypass the solenoid for the DC/DC charger. You need cables for 30A with low voltage drop, not 300A for starting. Put the charger close to the house batteries so voltage drop in the wiring after the charger is minimized. Add another solenoid and remote switch if needed to disconnect the charger if that's desireable, or just a manual switch in a convenient place.
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