| Author |
Message |
sgirard
Samba Member
Joined: September 18, 2014
Posts: 93
Location: Spokane, WA
|
 Posted: Wed Jul 28, 2021 1:55 pm Post subject: Do I need a DC/DC charger? |
 |
|
Hi Folks:
Last year I replaced my house battery with a lifepo4 battery when I added a solar setup, and this year replaced the magnatek "converter" with Victron AC/DC charger.
So far so good. The question I have is whether I need to add a DC/DC charger to this setup (and if so any recommendations on where to mount it?). Primarily I'm wondering if this might be important due to the different voltages/chemistries between the starting and house battery.
Not looking to add gear I don't need, but will do if there's good reason.
Thanks,
-sean
_________________
95 EVC
--------------
Previous:
64/71/72/82
--------------
Intro |
|
| Back to top |
|
 |
TheOneTrueQuux
Samba Member
Joined: May 26, 2021
Posts: 363
Location: Winona, MN
|
| Posted: Wed Jul 28, 2021 2:27 pm Post subject: Re: Do I need a DC/DC charger? |
|
|
Yeah, you need it for two reasons.
1.) You'll never fully charge the Lithium Iron Phosphate battery without it.
2.) If you ever fully discharge your battery, it could kill your alternator while re-charging. The DC-DC charger current limits this.
I'm eventually planning the same thing. I plan to put the DC-DC in the back where the Magnetek used to reside, and where I mounted the victron replacement.
I think I'll be able to re-use all the wiring, and I should be able to just connect the two wires that go to the solenoid relay together. |
|
| Back to top |
|
|
sgirard
Samba Member
Joined: September 18, 2014
Posts: 93
Location: Spokane, WA
|
| Posted: Wed Jul 28, 2021 2:35 pm Post subject: Re: Do I need a DC/DC charger? |
|
|
Umm... where would I find the wires that go to the solenoid relay 
| TheOneTrueQuux wrote: |
I think I'll be able to re-use all the wiring, and I should be able to just connect the two wires that go to the solenoid relay together. |
_________________
95 EVC
--------------
Previous:
64/71/72/82
--------------
Intro |
|
| Back to top |
|
|
subdewd
Samba Member
Joined: January 16, 2018
Posts: 238
|
| Posted: Thu Jul 29, 2021 4:54 am Post subject: Re: Do I need a DC/DC charger? |
|
|
How could the alternator get ruined by charging a lithium battery?
I'm thinking about doing the battery upgrade too. Suggestions for the DC DC vharger? |
|
| Back to top |
|
|
TheOneTrueQuux
Samba Member
Joined: May 26, 2021
Posts: 363
Location: Winona, MN
|
| Posted: Thu Jul 29, 2021 6:55 am Post subject: Re: Do I need a DC/DC charger? |
|
|
| subdewd wrote: |
How could the alternator get ruined by charging a lithium battery?
I'm thinking about doing the battery upgrade too. Suggestions for the DC DC vharger? |
Lithium batteries can pull very large amounts of current when charging, a 100 Ah battery can pull 100+ A when charging from fully discharged. This will overheat and fry your alternator. Newer vehicles have better protection from this, but most older ones don't have any.
Victron and Renogy both have nice units. I'm partial to Victron and they have bluetooth monitoring built in.
This model in particular seems ideal:
https://www.amazon.com/Victron-Energy-Orion-Tr-Non-Isolated-Bluetooth/dp/B086Q8YNJZ/
Renogy has similar stuff for cheaper, but their product support is supposedly kind of sketchy. |
|
| Back to top |
|
|
sgirard
Samba Member
Joined: September 18, 2014
Posts: 93
Location: Spokane, WA
|
| Posted: Thu Jul 29, 2021 8:46 am Post subject: Re: Do I need a DC/DC charger? |
|
|
I guess a related question... showing my ignorance here. Is there a way to just disconnect the coach battery from the alternator without disconnecting the battery altogether? I have a disconnect installed to disconnect it from the system entirely. I really don't necessarily need the alternator charging piece, but I do want to use to coach battery to power 12v outlets while driving.
I have a pretty good handle on the "house" wiring side of things, but the interaction with the alternator is still a bit of a mystery to me. I think I understand it conceptually but I don't know all the components involved.
Thanks for the feedback so far everyone!
_________________
95 EVC
--------------
Previous:
64/71/72/82
--------------
Intro |
|
| Back to top |
|
|
TheOneTrueQuux
Samba Member
Joined: May 26, 2021
Posts: 363
Location: Winona, MN
|
| Posted: Thu Jul 29, 2021 11:37 am Post subject: Re: Do I need a DC/DC charger? |
|
|
| sgirard wrote: |
| I guess a related question... showing my ignorance here. Is there a way to just disconnect the coach battery from the alternator without disconnecting the battery altogether? |
Yeah, you could disconnect the trigger wire from the battery isolator solenoid/relay that's mounted to the firewall right above the battery. That would make it so that the two systems weren't connected when the key is on. |
|
| Back to top |
|
|
writing from the road
Samba Member
Joined: January 19, 2021
Posts: 1
Location: SW
|
| Posted: Mon Aug 09, 2021 4:17 pm Post subject: Re: Do I need a DC/DC charger? |
|
|
Curious if anyone made this connection work yet?
We have a 2003 Eurovan camper and have had an interesting time finding someone to help correctly install the new lithium battle born battery. The solenoid complicates everything- so I've heard.
First we upgraded the battery converter charger using per Go Westy to this newer one
Progressive Dynamics PD9130LV 12V Lithium Ion Battery Converter/Charger - 30 Amp (works great)
and bought the Orion-Tr Smart isolated DC-DC 12/12/30 charger by victron energy recommended and bought from Battleborn, works well
and the battle born lithium battery.
All have been installed, and 'our' guy got confused somewhere,
and somehow disconnected the solenoid, and did not connect the lithium correctly.
We took it out camping and realized the camper is running off the main battery only. After it died and recharged, use a voltage meter to see everything everything matches the 13.4V started battery and nothing is reading the 14.4V from lithium. Oh my god!! someone help!!!!
No one seems to know what to do with the solenoid and the dc/dc charger.
Any thoughts? Any thoughts?
Thanks |
|
| Back to top |
|
|
orbeamike
Samba Member
Joined: May 16, 2017
Posts: 150
Location: California
|
| Posted: Tue Aug 10, 2021 8:19 am Post subject: Re: Do I need a DC/DC charger? |
|
|
You need to start with a stock Eurovan wiring diagram and trace back to what has been done so far. the wiring diagram can be downloaded from the web.
I looked into this conversion a little while back and made some notes, I plan to use a Renogy DCC30S instead of Vectron, but the connection should be similar. If the Vectron has built in isolation circuit like the Renogy then you will need to bypass the isolation solenoid. Most of the wiring happens under the wardrobe cabinet next to the converter/heater.
|
|
| Back to top |
|
|
TheOneTrueQuux
Samba Member
Joined: May 26, 2021
Posts: 363
Location: Winona, MN
|
| Posted: Tue Aug 10, 2021 12:04 pm Post subject: Re: Do I need a DC/DC charger? |
|
|
| orbeamike wrote: |
| If the Vectron has built in isolation circuit like the Renogy then you will need to bypass the isolation solenoid. |
Just a note here. "Isolated" in the context of Victron marketing terms for DC-DC converters means that the grounds on the input and output side need not be the same, and indeed don't need to be connected.
All the Victron DC-DC converters have a start-stop function that can either be automatic (sensing of input voltage rise due to alternator charging) or via a switch or input wire (the wire that feeds the existing isolation solenoid). |
|
| Back to top |
|
|
orbeamike
Samba Member
Joined: May 16, 2017
Posts: 150
Location: California
|
| Posted: Tue Aug 10, 2021 2:57 pm Post subject: Re: Do I need a DC/DC charger? |
|
|
| I took a quick look at the Orionn-Tri smart isolated datasheet, it works with a smart alternator with a fixed output of 14V. Our 20+ years old alternators are "not smart" and its output voltage various depending on the RPM........I would ask Victron tech support whether the Orion works with with our alternator. |
|
| Back to top |
|
|
Blaque Jacques
Samba Member
Joined: February 06, 2018
Posts: 114
Location: Moab
|
| Posted: Tue Aug 10, 2021 5:15 pm Post subject: Re: Do I need a DC/DC charger? |
|
|
I took a different approach that seems to be working. I replaced the solenoid with a victron cyrix CT-Li 230 voltage sensing battery combiner/isolator in the engine compartment. I also installed a 150amp alternator. my current setup is using a standard lead acid group 31 105 ahr battery but it works great. Why wouldn't doing the same thing with the victron CT-Li 230 combiner work with a lifepo battery?
_________________
86 2wd Westy GW2200. 97, 99 02 EVC. Lots and lots of bikes |
|
| Back to top |
|
|
orbeamike
Samba Member
Joined: May 16, 2017
Posts: 150
Location: California
|
| Posted: Tue Aug 10, 2021 10:15 pm Post subject: Re: Do I need a DC/DC charger? |
|
|
| Blaque Jacques wrote: |
| I took a different approach that seems to be working. I replaced the solenoid with a victron cyrix CT-Li 230 voltage sensing battery combiner/isolator in the engine compartment. I also installed a 150amp alternator. my current setup is using a standard lead acid group 31 105 ahr battery but it works great. Why wouldn't doing the same thing with the victron CT-Li 230 combiner work with a lifepo battery? |
I think Cyrix is just an isolation circuit for the house battery and starter battery. You still need a Dc-DC charger to provide 14V+ charging voltage and over current protection to protect the alternator. |
|
| Back to top |
|
|
dazey77
Samba Member
Joined: May 11, 2020
Posts: 163
Location: Other side of the pond.
|
| Posted: Wed Aug 11, 2021 2:45 am Post subject: Re: Do I need a DC/DC charger? |
|
|
| orbeamike wrote: |
You still need a Dc-DC charger to provide 14V+ charging voltage and over current protection to protect the alternator. |
This is simply misleading.
a)there are real advantages in having a DC-DC. I have the Cyrix and it is fine for what I need
b)You dont need a DC-DC converter if the solar (and or the AC charger) provides the main source of charge
c) the alternator protection bit (there are some victron videos about the problem) only applies to smart alternators
Using the Cyrix is cheap and simple. The downside is that charge voltage and therefore the power you can get from the alternator to the battery is limited.
A downside of the cyrix some have found. You can't (at least on some) limit the charge current, so if its a 100w cyrix it will take 100w from the alternator. Some people with older vans found they were taking more power than the alternator could really handle (was vanagon I think I saw problems with)
For me the Cyrix is a good emergency way of topping up in winter, it will take a (really) long time to fill my battery. The van charge circuit is meant to be 14.4v, so even with voltage drop, enough to mostly charge a lithium, I find mine is often only 13.9 though. My lithium battery would fill a lot faster with a DC-DC rather than the cyrix. I have a 250w panel though, so its really not important to me.
(Taking price and space considerations out of the equation, DC-DC would be prefered of course)
_________________
My van modification blog:
www.dazedproductions.co.uk/Vanity
Last edited by dazey77 on Wed Aug 11, 2021 3:21 am; edited 1 time in total |
|
| Back to top |
|
|
dazey77
Samba Member
Joined: May 11, 2020
Posts: 163
Location: Other side of the pond.
|
| Posted: Wed Aug 11, 2021 2:57 am Post subject: Re: Do I need a DC/DC charger? |
|
|
| TheOneTrueQuux wrote: |
Yeah, you need it for two reasons.
1.) You'll never fully charge the Lithium Iron Phosphate battery without it.
2.) If you ever fully discharge your battery, it could kill your alternator while re-charging. The DC-DC charger current limits this.
|
1 is completly wrong. He can fully charge the battery with solar if he has a big enough panel (he doesn't say) or via his AC charger. He wont ever fully charge it soely from the van alternator, this is true but not important to many.
2 yes a DC-DC has a limit, set by which model you buy but the ability to draw power when the battery is los is also no different to the standard Eurovan setup. The charge circuit is protected by 40A fuses and the lead acid + fridge could pull a lot of current. I have never pulled as much current from the van with Cyrix, lithium, compressor fridge and solar as I did with lead acid and the original absorption fridge.
Because lithium has a higher voltage, a low battery doesn't pull the kind of charge voltages you would expect from the van circuit. Even a low lithium can be higher than the van battery
_________________
My van modification blog:
www.dazedproductions.co.uk/Vanity |
|
| Back to top |
|
|
TheOneTrueQuux
Samba Member
Joined: May 26, 2021
Posts: 363
Location: Winona, MN
|
| Posted: Wed Aug 11, 2021 7:51 am Post subject: Re: Do I need a DC/DC charger? |
|
|
| orbeamike wrote: |
| I took a quick look at the Orionn-Tri smart isolated datasheet, it works with a smart alternator with a fixed output of 14V. Our 20+ years old alternators are "not smart" and its output voltage various depending on the RPM........I would ask Victron tech support whether the Orion works with with our alternator. |
It does work just fine with both smart and dumb alternators.
Also, "smart" alternators work opposite what you just described. "dumb" alternators try to maintain a fixed output voltage, subject to limitations due to shaft speed, temperature, etc. Smart alternators are controlled by the vehicle electronics, and enable things like reducing alternator output briefly during heavy acceleration, or to help stabilize idle. They also can do a simple form of regenerative braking. This is the reason modern BMWs require the battery to be "paired" with the car on replacement. They have an aging model in the car electronics, and have to account for the health of the battery when doing regen so they don't cook it.
With smart alternators you might need the switching wire, with dumb ones you don't. |
|
| Back to top |
|
|
sgirard
Samba Member
Joined: September 18, 2014
Posts: 93
Location: Spokane, WA
|
| Posted: Wed Aug 25, 2021 8:16 pm Post subject: Re: Do I need a DC/DC charger? |
|
|
Thanks for the discussion everyone. Does anyone have a suggestion as to where to install a DC/DC charger? I have installed an AC/DC charger to replace the magnatek and also a PV (solar) charger. Those were both pretty straightforward, but I’m not clear where to hook into the circuit for DC/DC. If anyone has a description or photo of your install it would be much appreciated!
_________________
95 EVC
--------------
Previous:
64/71/72/82
--------------
Intro |
|
| Back to top |
|
|
dazey77
Samba Member
Joined: May 11, 2020
Posts: 163
Location: Other side of the pond.
|
| Posted: Thu Aug 26, 2021 6:26 am Post subject: Re: Do I need a DC/DC charger? |
|
|
I put my Cyrix (not DC-DC but same basic connectivity requirements) where the AC-DC converter was.
The original installation has the charging solenoid by the battery in the engine bay, a hanging 40A fuse by the fusebox. The cables from that run to the rear wiring.
I replaced the solenoid with a waterproof inline fuseholder with 40A fuse.
I replaced the cab fuse with a heavy duty switch mounted in the dash to allow me to disconnect charging.
I found where the cabling from the cab arrives and put the Cyrix between that and the rest of the cabling.
You may find that Victron say the DC-DC should be installed vertically (its the case for the solar MPPTs)
I actually removed my rear fuseboard and replaced it with a different style fuseboard and have the fuses, mppt and cyrix where the AC/DC converter was (I have no AC in my van anymore). I have any easy entry plate where the old fuseboard was (on Dzus fittings)
_________________
My van modification blog:
www.dazedproductions.co.uk/Vanity |
|
| Back to top |
|
|
sgirard
Samba Member
Joined: September 18, 2014
Posts: 93
Location: Spokane, WA
|
| Posted: Thu Aug 26, 2021 7:00 am Post subject: Re: Do I need a DC/DC charger? |
|
|
Interesting idea to put the fuse in place of the solenoid. I had assumed I’d just keep that in place. Did you delete the ignition trigger wire as well then?
I sure wish I had thought of this when I had the furnace out this spring and did the AC/DC.
_________________
95 EVC
--------------
Previous:
64/71/72/82
--------------
Intro |
|
| Back to top |
|
|
dazey77
Samba Member
Joined: May 11, 2020
Posts: 163
Location: Other side of the pond.
|
| Posted: Thu Aug 26, 2021 7:17 am Post subject: Re: Do I need a DC/DC charger? |
|
|
Yes, I removed the ignition trigger wire completly from the fuse box/engine bay.
One downside of my arrangement is that to run the van radio from the leisure battery required me to run in a new cable between the back and the cab. With the old arrangement I could have tapped off the charge cable.
You could consider finding a place in the engine bay as well of course, I believe there is some form of IP rating on the DC-DC but I would suggest you check throurghly if you want to go that way.
_________________
My van modification blog:
www.dazedproductions.co.uk/Vanity |
|
| Back to top |
|
|
|
