DC - DC charger on Mk7 Transit Dual Battery system

[fitzfarseer]

Hi all,

Tried asking this over on the Ford Transit forum, but to no avail. Thought you fine folks might be able to offer more wisdom!

Currently planning out the wiring and electrical components that will be going in my camper conversion, and I'd like to use a DC to DC battery charger in order to charge the van battery and the leisure battery via the alternator when driving as well as through solar. I'm looking at the Renogy charger with built in MPPT at the moment due to the cost, ease of use, and ability to charge batteries of different chemistry simultaneously, although I know this has limitations, so I am looking at other available chargers, such as those by Victron and Redarc.

However, my MK7 2010 Transit has two batteries under the drivers seat. From what I understand, the back one is the starter, and the front one is the auxiliary battery, and that they are only connected when the ignition is on. I believe they are connected via a split charge relay, or something very similar.

My question is would it be possible to charge both these under seat batteries as well as the back leisure battery using this one DC to DC charger, and how I might go about doing that? Or if that isn't a goer, any other ideas? Removing the under seat auxiliary battery entirely?
I ask because it is likely that I won't be driving the van too much, and I don't want the auxiliary battery dying, as I've heard it can cause all sorts of strange things to happen...

Worth noting that the under seat batteries are both lead-acid, whereas the leisure battery is lithium. All 12v.

Cheers!

 

[pollenface]

Exact same system I have in my vehicle. I use a dc-dc charger connected to the auxillary, as the starter & auxillary are connected at 13.3v

 

[fitzfarseer]

Exact same system I have in my vehicle. I use a dc-dc charger connected to the auxillary, as the starter & auxillary are connected at 13.3v

Cheers for the response.
Do you ever have any problems with that setup? I'm mainly concerned about either of the under seat batteries going flat leaving me stranded in the middle of nowhere..

Also can I ask what charger you use? I'm fairly new to the solar game so I'm trying to learn all I can at the moment!

 

[pollenface]

No problems to date, the dc-dc charger cuts out when the aux battery falls below 12.8v (as does the other vsr connected to the main starter). I leave the Aux battery as a starter backup and run my fridge and camping stuff from the big deep cycle

I have a powertrain 20 amp dc-dc charger, It's a $100aud 3-stage ebay jobbie. I had to run a big fat wire to it through the middle of the car but all good.

 

[dirt diggler]

I think we chatted on the transit forum ? the 2 base vehical batterys are connect when IGN is on by a normal relay (also helps with the glowplug load pre cranking).
I have a seperate solar panel for the Aux (front) battery in my Mk7, i used to have a VSR from the starter to the Aux so my DCC50s would charge both when the house battery was full (IE - house Via BtoB to starter, starter to Aux via VSR, both ways work fine, i only removed the VSR cos
A i had a spare small solar panel useless for anything else (30W with PWM)
B i wanted to use the VSR to power a load when the engine was running and it was cheaper to just use what i had.
If that helps at all ?

 

[Vee_u]

Cheers for the response.
Do you ever have any problems with that setup? I'm mainly concerned about either of the under seat batteries going flat leaving me stranded in the middle of nowhere..

Also can I ask what charger you use? I'm fairly new to the solar game so I'm trying to learn all I can at the moment!

Hello! I'm in the same dilemma. My Transit has the twin batteries under the drive seat and I am trying to figure out if the DC-DC from Victron (Orion Tr Smart 12-12 30A) would work in my case. Which dc-dc did you use at the end?

 

[fitzfarseer]

Hello! I'm in the same dilemma. My Transit has the twin batteries under the drive seat and I am trying to figure out if the DC-DC from Victron (Orion Tr Smart 12-12 30A) would work in my case. Which dc-dc did you use at the end?

Hi! I got the very one that you're considering. The non-isolated version.
That version is for when you have a common ground, which in my case (and probably yours) I do.
I plan to connect it directly to the aux battery, and as Dirt Diggler above suggested, I'll probably use a small portable solar panel or battery maintainer to keep the starter battery topped up when I'm not driving for a while ?

 

[John Frum]

I plan to connect it directly to the aux battery

Is that the house battery?

 

[fitzfarseer]

Is that the house battery

No, as in this case the van comes as standard with a starter battery and an aux battery to power things like the radio and/or cargo lights and accessories etc.
I've added a house/leisure battery in the back, completely separate from the front two, and of course the dc-dc will run between the leisure battery, and in my case the front aux battery.

 

[ste550]

Hello! I'm in the same dilemma. My Transit has the twin batteries under the drive seat and I am trying to figure out if the DC-DC from Victron (Orion Tr Smart 12-12 30A) would work in my case. Which dc-dc did you use at the end?

Hiya, wondering how you got on, had mine connected to the starter battery but aux battery went flat and caused loads of errors when I put it back on, so connected the renogy DC/DC to the 60 amp fuse on the bus bar under the seat, sorted the faults out but in hindsight the solar won't charge the starter battery as the relay shuts off, house batterys ok, a bit of a dilemma really, might connect it back to the starter and blame the cold weather.

 

[dirt diggler]

Hiya, wondering how you got on, had mine connected to the starter battery but aux battery went flat and caused loads of errors when I put it back on, so connected the renogy DC/DC to the 60 amp fuse on the bus bar under the seat, sorted the faults out but in hindsight the solar won't charge the starter battery as the relay shuts off, house batterys ok, a bit of a dilemma really, might connect it back to the starter and blame the cold weather.

They all do that sir lol TBH it's the aux battery that has a load and so will be the one that goes flat so your probably better off on that one rather than the starter battery that has zero load and only has to deal with the usuall FLA self discharge, one of those sub £20 dash solar panels will be fine (i have them in all my motors) get at least a 20W one
without mods the only way round the issue is start the van at least once a week and run it for over 30 mins, IMHO a seperate solar panel is cheaper than the fuel to do this ?

 

[ste550]

Hiya, thanks for replying, just taken the seat off again, was looking at the wiring and both batterys are connected via the earth so am reckoning connecting to the front aux battery thinking it'll charge both on solar, will do tomorrow but they've been spraying and its just a grey mass of cloud but may be sunny tomorrow. Thanks again.

 

[dirt diggler]

They are seperated by an ign triggerd relay that only connects them together with ign on so they wont both charge
hense why i say fit a seperate on dash solar pannel for the "other" battery

 

[Merc814]

Has anyone had success so far. I'm also fitting a victron Orion DC to DC charger to my mk7 transit and pondering where to go from, the alternator or the batteries and therefore which one?

 

[mikefitz]

the batteries and therefore which one?

The starter battery would be the better choice.
CCP1 on the seatbase is fused (at 60 amps ?) , connect the Orion to this. Take the negative feed from a suitable body earth point, not the battery.

 

[justinm001]

Take the negative feed from a suitable body earth point, not the battery.

Why is this? I understand this for jumpstarting cars as a dead battery will absorb more power than the starter if it's dead but I don't see any reasoning why you wouldn't want to homerun from the battery instead of body

 

[Merc814]

Why is this? I understand this for jumpstarting cars as a dead battery will absorb more power than the starter if it's dead but I don't see any reasoning why you wouldn't want to homerun from the battery instead of body

Oh, I always thought it was to keep possible arcing away from any gasses leaked from the battery.

I'll likely run the neg to the battery. Can't see any particular reason to use chasis and it would also be the closest connection point.

 

[mikefitz]

Can't see any particular reason to use chasis

The Transit has smart charging that has a sensor between the battery negative post and body/chassis to determine the state of starter battery condition. If you bypass this by connecting your house battery direct to the starter negative the vehicle no longer is able to correctly compute starter battery state.
There will be a suitable body earth point near the battery.