yet another house battery charging question

[dado5]

I have read most of the threads on house battery charging and dc-dc chargers and am now more confused than ever. I am looking for a basic setup. Here is where I'm at now:
2016 Ford transit 350 with HD alternator. I have 100w solar on roof charging an odyssey blue battery in the back of the van, mainly to power my ARB fridge. This is not a camper, but my family trip car.

I would like to add charging to the house battery while driving, we do a lot of driving at night and there is no solar input. In the transit I have 2 house batteries under the driver seat and 3 accessory 12volt 60 amp terminals on the side of the drivers seat. I also have a blue seas ML-ACR which I bought for a different project and never used. The distance from the auto batteries to my house battery is 12-14 feet. I would rather not have to run large battery cable that far if all I need is a few amps to charge. I was thinking of just putting an inverter back by the house battery powered from one of the 60A terminals and then I can plug in a smart 110v car charger to do the charging. What size wire would I need for that?

If I use the blue seas unit where would you place it? Closer to the house battery or auto battery? I don't need a full rv setup here, just want to charge the battery while moving. If I went the inverter route I could also plug the ARB into that along with the charger I suppose.

any thoughts?

 

[Buddha.]

Clarification needed
You have two house batteries under your driver’s seat, you want to run an inverter and a 110v charger off that to charge an additional house battery(odyssey) that’s located in the back?
Do you have two house banks?
How are you charging the bank under your drivers seat?

 

[Martinjmpr]

If I'm reading right you have 4 batteries? The truck battery, two house batteries under the driver's seat and another house battery in the back of the van, is that right? Why so many batteries? What are the batteries under the driver's seat for?

If you have 2 batteries under the driver's seat, why not just use those for the fridge? I think I have a 12' power cord for my fridge. Assuming that the two batteries under the seat are connected to the alternator, that should be more than adequate to run your fridge.

What am I missing here?

 

[john61ct]

Yes best design is one big House bank, not multiple.

Unless you are driving 7+ hours at a time, the alternator output (any ICE source) will just add some charge, not get any batteries to 100% Full, which is required for lead bank longevity.

Solar or mains are required for that.

If you don't buy a DCDC charger, then the wire gauge must be fat in order to reduce voltage drop.

You either need to spend a lot of money, or precisely measure & calculate to get by at minimum cost.

Or just replace the batteries more frequently.

 

[dado5]

the batteries under the seat are the auto batteries, that’s where the factory puts them.

 

[john61ct]

> In the transit I have 2 house batteries under the driver seat

Just to be clear, you are now saying these are **not** a House bank, but only used for cranking and other engine-related needs?

If you are using vehicle lights, ventilation, stereo etc for more than a few minutes while the engine is not running, especially camping or living off grid,

these and any other "auxiliary" loads should ideally be moved over to a House bank.

All an ACR / VSR does is isolate your Starter batt from the House circuits when no charge source is active. They are voltage following, no boost of voltage, source drops to Float so do all connected banks on both sides.

Most DC-DC chargers include that isolation function, as well as giving the voltage a boost, target bank getting its own independent charge profile. But they are one-way only, while ACR / VSR are often dual sense, sources can activate the switch closing (combining) from either the Starter (engine) or House circuit.

 

[dado5]

Yes not a house bank. They are just the car batteries. I ordered a bcdc redarc charger. Should be fine. Thanks for the replies

 

[rayra]

I have read most of the threads on house battery charging and dc-dc chargers and am now more confused than ever. I am looking for a basic setup. Here is where I'm at now:
2016 Ford transit 350 with HD alternator. I have 100w solar on roof charging an odyssey blue battery in the back of the van, mainly to power my ARB fridge. This is not a camper, but my family trip car.

I would like to add charging to the house battery while driving, we do a lot of driving at night and there is no solar input. In the transit I have 2 house batteries under the driver seat and 3 accessory 12volt 60 amp terminals on the side of the drivers seat. I also have a blue seas ML-ACR which I bought for a different project and never used. The distance from the auto batteries to my house battery is 12-14 feet. I would rather not have to run large battery cable that far if all I need is a few amps to charge. I was thinking of just putting an inverter back by the house battery powered from one of the 60A terminals and then I can plug in a smart 110v car charger to do the charging. What size wire would I need for that?

If I use the blue seas unit where would you place it? Closer to the house battery or auto battery? I don't need a full rv setup here, just want to charge the battery while moving. If I went the inverter route I could also plug the ARB into that along with the charger I suppose.

any thoughts?

$30 solenoid, keyed-power triggered, tied to your factory alternator / starter batter charging circuit, and sufficiently thick wiring to pass the full output of your vehicle alternator to your aux. It's brute simple and reliable and inexpensive. And utterly bereft of 'smart' points of failure.

why oh why do you people keep trying to RESTRICT your vehicle's native charging ability by interposing expensive devices of lower throughput. Or even adding them at all.

 

[rayra]

Yes not a house bank. They are just the car batteries. I ordered a bcdc redarc charger. Should be fine. Thanks for the replies

lol. I'm starting to think it is just some clumsy surreptitious marketing campaign by Redarc, given the profligacy of DC-DC / Redarc threads in recent weeks. Or some fount of 'Youtube influencer' is producing all this muddled nonsense. ~$500 'solutions' to $50 problems.

 

[highwest]

why oh why do you people keep trying to RESTRICT your vehicle's native charging ability by interposing expensive devices of lower throughput. Or even adding them at all.

I see you say this often. I am confused about charging because it is often said that batteries must have a certain charge profile (bulk, float, desulfation, temperature compensation, etc.) to maintain long term battery health (especially expensive, exotic varieties, deep cycles, etc.). Can you help me understand the impact of charging a house battery straight from the alternator vs having some form of charge controller control in between?

 

[DiploStrat]

I see you say this often. I am confused about charging because it is often said that batteries must have a certain charge profile (bulk, float, desulfation, temperature compensation, etc.) to maintain long term battery health (especially expensive, exotic varieties, deep cycles, etc.). Can you help me understand the impact of charging a house battery straight from the alternator vs having some form of charge controller control in between?

You are confusing your vehicle's starter battery and a deep cycle camper battery. Why would you think that the vehicle manufacturer would not install a proper charging system for the vehicle's battery? They certainly don't want extra warranty charges.

The challenge comes when you pair the starter battery, which typically gets only light use, with a camper battery, which will typically be deeply discharged regularly. Thus the camper battery should be a deep cycle, rather than starter, battery and may or may not be of the same chemical formulation as the starter battery, e.g. lead acid vs. lithium. Further, different vehicle manufacturers approach the care and feeding of their starter batteries differently. Some Toyotas, for example, only charge to 13.9v while most GM vehicles will surge up to 15.5v.

Given the tight integration between your vehicle's electrical system and the starter battery, you probably don't want to install anything between them.

There are many ways to properly charge a camper battery, ranging from a manual or key controlled switch, to an voltage sensing switch, to a battery to battery charger, to a full on second alternator. One or more may be proper for your installation, but you would need to sit down with someone who knows what they are doing.

My previous camper used a voltage sensing relay and my current vehicle uses a REDARC battery to battery charger - different vehicles, different problems. As much as I like REDARC gear, in think that, in the instant case, the original poster has wasted his money and may be about to make his vehicle undrivable. You do not want to put a battery to battery charger, REDARC, Sterling, or whomever, between the alternator and the starter battery.

 

[highwest]

You are confusing your vehicle's starter battery and a deep cycle camper battery. Why would you think that the vehicle manufacturer would not install a proper charging system for the vehicle's battery? They certainly don't want extra warranty charges.

The challenge comes when you pair the starter battery, which typically gets only light use, with a camper battery, which will typically be deeply discharged regularly. Thus the camper battery should be a deep cycle, rather than starter, battery and may or may not be of the same chemical formulation as the starter battery, e.g. lead acid vs. lithium. Further, different vehicle manufacturers approach the care and feeding of their starter batteries differently. Some Toyotas, for example, only charge to 13.9v while most GM vehicles will surge up to 15.5v.

Given the tight integration between your vehicle's electrical system and the starter battery, you probably don't want to install anything between them.

There are many ways to properly charge a camper battery, ranging from a manual or key controlled switch, to an voltage sensing switch, to a battery to battery charger, to a full on second alternator. One or more may be proper for your installation, but you would need to sit down with someone who knows what they are doing.

My previous camper used a voltage sensing relay and my current vehicle uses a REDARC battery to battery charger - different vehicles, different problems. As much as I like REDARC gear, in think that, in the instant case, the original poster has wasted his money and may be about to make his vehicle undrivable. You do not want to put a battery to battery charger, REDARC, Sterling, or whomever, between the alternator and the starter battery.

No, I understand that charging the starting battery should only be done from the vehicle's alternator.

@rayra often recommends also charging house batteries from the alternator. I very much appreciate simplicity, so I get where he’s coming from on that front, but I also worry that the alternator may damage house battery(ies) when they are deep cycle or not of traditional lead acid chemistry.

 

[DiploStrat]

No, I understand that charging the starting battery should only be done from the vehicle's alternator.

@rayra often recommends also charging house batteries from the alternator. I very much appreciate simplicity, so I get where he’s coming from on that front, but I also worry that the alternator may damage house battery(ies) when they are deep cycle or not of traditional lead acid chemistry.

I had a 2013 Chevrolet Silverado HD with 600Ah of Lifeline AGM camper batteries. The Chevrolet did a great job of charging them, for years. As the batteries were some 25 feet from the starter batteries I used a pair of 0 AWG cables and a voltage sensing relay. GM's charging system is superb. Part of the reason being that GM uses lead calcium batteries which like a lot of voltage and this helps to cover any voltage drop through the cables.

So, in this case, he is correct. All kinds of info on my website, here: https://diplostrat.net/documents/

 

[rayra]

No, I understand that charging the starting battery should only be done from the vehicle's alternator.

@rayra often recommends also charging house batteries from the alternator. I very much appreciate simplicity, so I get where he’s coming from on that front, but I also worry that the alternator may damage house battery(ies) when they are deep cycle or not of traditional lead acid chemistry.

All you have to do is charge them fully to their higher required voltage periodically, not constantly. And except for most of us older farts with older vehicles, I would expect most of the newer / newest vehicles will do so sufficiently. Charging at 14.6-7 rather than 14.2-3. Too, having solar and any modern charge controller - even PWM where you can set the battery type - you get your fancier battery sufficiently topped that way. Depending on your usage pattern.

I'm using an inexpensive 200A solenoid to join my Aux and Start batteries when the vehicle is running / charging. I've also got a rooftop panel and inexpensive Renogy PWM charging / conditioning my Aux all the time. And in a recent upgrade I added a higher-output replacement alternator in the 200+ range which also happens to operate at 14.6-7, as opposed to my GM factory / original alternator operating at a lower voltage. I could now host a fancier / different battery type with my current charging infrastructure, but I've chosen matching grp78 SLA batteries for different reasons. Chiefly for interchangability if I'm far off the beaten path and mostly to use both combined - and vehicle running - while running a 12k winch. Which were my primary design goals when I first ran heavy cabling to the rear of my vehicle.
All the other 'options' for providing different power outputs and inputs all followed.

So, your glamper sits around or is your daily driver, except for a few trips a year, during which you have some heavier draws for your fridge / electronics / entertainment / blender. And you want to arrive topped up, or top up quickly while shunting from one couple-day campsite to another. During which drive you want a maximal bulk charge to your 'house' battery. Which I why I think these expensive restrictive charging devices are utterly wrong. That the full available power of your vehicle's factory charging system should be supplied to your 'house' batt while your vehicle is running. Use your solar to feed your house. Or feed the specialty charger to reach the higher charge requirements of the AGW/whatever lithium tech battery.

And too, if the longer duration trips are infrequent, dismount that house battery and put it on a dedicated maintainer to ensure its longevity.

It's a matter of primary design goals / needs and designing your system to meet them. And IMAO it's about max available power while in the field, and not chiefly about servicing a very expensive battery tech, in the middle of your camping trip.

 

[john61ct]

I completely agree, that

**if** the voltage **measured at the House bank posts** is within the battery mfg specs

and the alternator keeps putting out that voltage for all the time you're driving around

then a DCDC charger is not required.

The OP was talking about a pretty long cable length, and not wanting to have to run a heavy gauge.

Which to me, makes it very likely a DCDC will help get the House bank charged more effectively, and likely faster, since current acceptance will likely be lower than the DCDC's output 90% of the time anyway.

And of course actually getting to 100% Full more quickly and often helps the House bank last longer.