TheSamba.com :: View topic

Tue Sep 14, 2021 1:51 pm

So I have a 1776cc engine with only 5k miles on it in my 69 bay window and I tried hooking up a DC to DC charger so I can charge my accessory batteries inside the bus when the solar isn't cutting it. (This is for a fulltime van life build.) I let the alternator warm up and only turned it on once I was cruising on the highway for a bit. Then my generator light came on and at first my generator light would shut off when at high RPM but then it stayed on constantly. I am assuming it was because the alternator wasn't strong enough to charge the car battery as well as the DC to DC charger.

Has anyone else tried putting on a DC to DC charger and had a similar problem or did yours work? If it did work...how?

Tue Sep 14, 2021 2:32 pm

Have you checked the voltage at the batteries and other points in the system?

Tue Sep 14, 2021 2:33 pm

better explain that again. You lost me totally. What kind of voltages for example are we working with - a small 12v cigarette lighter charger to a cell phone type connection? cables running thru a two battery system? How you are turning your "alternator" on and off is beyond me. You can't unload a car alternator from all car batteries without the potential to damage it, and one can't disconnect the fan belt from an 'alternator' on an upright engine without melting the engine when it loses cooling fan air. So please do a better job of explaining yourself.

Tue Sep 14, 2021 2:38 pm

Maybe try charging the batteries with an ac charger first then see if it still happens. Sounds like a bad battery or something wired wrong. You probably blew the alternator.

Tue Sep 14, 2021 2:57 pm

I don’t mean this to sound rude, but the term VanLife implies someone on YouTube probably got paid to promote a DC to DC charger… Useless things they are…

A 55-amp alternator is more than up to the task of charging both batteries. VW coupled dual batteries directly together with a standard four-pin relay, and most vendors sell that kit for $20, though the wires they include are too small and have a habit of melting. (Seriously, dudes?)

BlueSea and some other marine companies make a charge relay with a delay built in so the starter battery fills before beginning to charge the leisure battery. If this the “DC to DC charger” you have, carry on! I don’t mean to poopoo the Vanlife world, but I see lots of good money spent after bad money from YouTube advice…

Robbie

Edited, not Type 4. Numbers are hard.

Tue Sep 14, 2021 3:13 pm

Wildthings wrote: Have you checked the voltage at the batteries and other points in the system?

Yeah and once i turned on the dc to dc charger my battery was just losing voltage and my accessory batteries didn't gain anything. So my alternator is definitely shot now but I want to know why like it is only a 20amp dc to dc charger which is the lowest grade they make.

Tue Sep 14, 2021 3:16 pm

How is your system wired? Ideally your house battery should be its own system, connecting to your Bus's 12volt system via relay or controller only when the engine is running (and alternator is producing a charge.) With the engine off the relay or controller should disconnect when the engine is shut off.

Take a look at the RV world for examples.

Edit: This is just my opinions on this coming from the RV world. Your results may vary.

Tue Sep 14, 2021 3:16 pm

airschooled wrote: I don’t mean this to sound rude, but the term VanLife implies someone on YouTube probably got paid to promote a DC to DC charger… Useless things they are…

The alternator on a Type 4 is more than up to the task of charging both batteries. VW coupled the batteries directly together with a standard four-pin relay, and most vendors sell that kit for $20, though the wires they include are too small and have a habit of melting. (Seriously, dudes?)

BlueSea and some other marine companies make a charge relay with a delay built in so the starter battery fills before beginning to charge the leisure battery. If this the “DC to DC charger” you have, carry on! I don’t mean to poopoo the Vanlife world, but I see lots of good money spent after bad money from YouTube advice…

Robbie 1776 should be a T1. 1969 bus.

Tue Sep 14, 2021 3:17 pm

SGKent wrote: better explain that again. You lost me totally. What kind of voltages for example are we working with - a small 12v cigarette lighter charger to a cell phone type connection? cables running thru a two battery system? How you are turning your "alternator" on and off is beyond me. You can't unload a car alternator from all car batteries without the potential to damage it, and one can't disconnect the fan belt from an 'alternator' on an upright engine without melting the engine when it loses cooling fan air. So please do a better job of explaining yourself.

So I have two AGM 12v batteries under my bed that I have my 300 watts of solar connected to but I also have a dog so I want to stay in the shade for him as well. So when I am driving I can turn on the dc to dc charger by hitting a switch on my dash and when it is on it will draw power from my car battery which should be replenished by the alternator. But when I tested it the alternator didn't replenish the car battery and seemed to have over worked it or something because now the alternator doesn't charge the car battery at all. I hope that clears it up a little.

Tue Sep 14, 2021 3:19 pm

Do you have a picture of this thing? Or a link?

Tue Sep 14, 2021 3:20 pm

cmonSTART wrote: How is your system wired? Ideally your house battery should be its own system, connecting to your Bus's 12volt system via relay or controller only when the engine is running (and alternator is producing a charge.) With the engine off the relay or controller should disconnect when the engine is shut off.

Take a look at the RV world for examples.

Edit: This is just my opinions on this coming from the RV world. Your results may vary.

Yeah I have it on a switch so I can turn it on and off. I was only going to be running it when on the highway because that is when the alternator should be putting out the most power to my car battery therefore replenishing it the best. I have the house batteries connected to the solar so I wouldn't be running the dc to dc all teh time just when the solar didn't collect as much as needed.

Tue Sep 14, 2021 3:24 pm

cmonSTART wrote: Do you have a picture of this thing? Or a link?

It is the Renogy Board 20A DC to DC Battery Charger Using Multi-stage Charging

https://www.amazon.com/gp/product/B07Q5VYPCF/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1

Tue Sep 14, 2021 3:36 pm

completely disconnect the system from your car battery carefully and see if the alternator charges the car battery. I would think that a 20 amp draw against a 50 - 60 amp alternator would not damage the alternator if all you are doing is turning the changer on and off to the spare batteries. However I can't see the rest of your wiring or circuits.

Tue Sep 14, 2021 3:47 pm

SGKent wrote: completely disconnect the system from your car battery carefully and see if the alternator charges the car battery. I would think that a 20 amp draw against a 50 - 60 amp alternator would not damage the alternator if all you are doing is turning the changer on and off to the spare batteries. However I can't see the rest of your wiring or circuits.

^^^

How old is is the alternator and regulator?

Tue Sep 14, 2021 4:11 pm

I am going to guess that you got the polarity of something hook up backwards and smoked the diodes in your alternator.

Tue Sep 14, 2021 5:54 pm

Is your dc-dc charger set up right, ie AGM?

Some can be set up to different battery types

Do you have an isolator? you really need an isolator so that if you starter battery isn't at a high enough voltage then no power is put to the 2nd battery

I know i'm in Australia, with different products but I would recommend RedArc gear, they are the type of things you buy once and that is it, they are that very well designed and tested that they hardly ever fail

I would recommend this isolator and this DC-DC charger, which you can also plug your solar into, it has a green function where it takes the solar 1st if the power is there then top up on alternator if needed

https://www.redarc.com.au/smart-start-sbi-12v-100a

https://www.redarc.com.au/dual-input-25a-in-vehicle-dc-battery-charger

Red Arc have diagrams of how to wire it up but basically, it's:

Alternator
Starter Battery
Isolator
DC-DC charger
Aux Battery bank

Plus also the solar can go into the DC-DC charger[/url]

Tue Sep 14, 2021 6:06 pm

I read the manual for your charger - looks to be a nice unit. Unlike a simple relay, it should result in a better quality charge on the house battery than the alternator can provide (as it's a "smart" charger) and still allow the vehicle battery to charge normally. I like the idea that the house battery can be a different chemistry than the vehicle battery, and yet charge it properly.

That said, I see no way that the unit could possibly overload the alternator, as it limits it's output current to 20 amps (10 amps if the limit terminal is at 12 volts). The type 1 alternator is good for 55 amps, so even at max output its draw is well within the alternator's rating (even better than the normal relay 'solution'). Side effect: the house battery could charge slower than a dual battery relay would provide - but that's OK, considering the quality of the charge.

One thing: with this charger, the house battery should never be directly connected to the vehicle battery, as this would drive the charger logic nuts and defeat its operation. If this is a camper, make sure there isn't a dual battery relay or diode isolator still somewhere in the wiring.

I'd recheck the wiring and do some voltmeter checks to test the state of the alternator. You should get 13.8 volts or better across then vehicle battery with the engine running at 2000 r/m or so.

Tue Sep 14, 2021 6:57 pm

airschooled wrote: I don’t mean this to sound rude, but the term VanLife implies someone on YouTube probably got paid to promote a DC to DC charger… Useless things they are…

The alternator on a Type 4 is more than up to the task of charging both batteries. VW coupled the batteries directly together with a standard four-pin relay, and most vendors sell that kit for $20, though the wires they include are too small and have a habit of melting. (Seriously, dudes?)

BlueSea and some other marine companies make a charge relay with a delay built in so the starter battery fills before beginning to charge the leisure battery. If this the “DC to DC charger” you have, carry on! I don’t mean to poopoo the Vanlife world, but I see lots of good money spent after bad money from YouTube advice…

Robbie Thank you.

Im not the only one who thinks the youtube vanlifers are absolute buffoons.

Tue Sep 14, 2021 7:48 pm

VOLTWAGEN wrote: Is your dc-dc charger set up right, ie AGM?

Some can be set up to different battery types

Do you have an isolator? you really need an isolator so that if you starter battery isn't at a high enough voltage then no power is put to the 2nd battery

I know i'm in Australia, with different products but I would recommend RedArc gear, they are the type of things you buy once and that is it, they are that very well designed and tested that they hardly ever fail

I would recommend this isolator and this DC-DC charger, which you can also plug your solar into, it has a green function where it takes the solar 1st if the power is there then top up on alternator if needed

https://www.redarc.com.au/smart-start-sbi-12v-100a

https://www.redarc.com.au/dual-input-25a-in-vehicle-dc-battery-charger

Red Arc have diagrams of how to wire it up but basically, it's:

Alternator
Starter Battery
Isolator
DC-DC charger
Aux Battery bank

Plus also the solar can go into the DC-DC charger[/url]

https://www.redarc.com.au/bcdc-dual-with-jump-start-feature-the-ultimate-battery-setup