Retrofit to charge chassis battery

[TerryJames]

Hi Folks,
Have not yet installed knife isolation switches. However, did put in JEGS jumper terminals and have used several times to make jumping easier from another vehicle. Don’t need to pop up the engine cover. Then purchased a NOCO GB40 … works OK on the FORD E450 10 cyl. when both house and chassis battery dead. Have been putting off the engine battery change-out till a few weeks from now.
https://www.jegs.com/i/JEGS/555/10314K/10002/-1
Unhooked the air hoses and ran a couple of short battery connections to the jumpers without disconnecting the battery. Not an answer for everyone ... but helps us.

[ducksface]

I installed EXACTLY the same on my atv 2 days ago.

[Farmer Folly]

Originally Posted by Travelin' Texans

I've never owned a motorhome, but have owned several towables, just curious is the chassis battery discharging an issue? There's several wondering how to keep them charged. What's discharging them while parked? On most vehicles once the key is off there's nothing discharging the battery.
As for the alternator, it's designed to keep a good battery topped off while traveling, it will take lots of miles to charge a 50% discharged battery with the alternator. It also would take forever to charge or keep charged a multi battery bank due small gauge wire.
If the converter is keeping the coach batteries fully charged then why not use jumper cables from them to start the vehicle if needed?
What am I missing here?

I also wonder what load exists on the chassis battery once the key is withdrawn and what causes this load. Others also have seen chassis batteries quickly go dead during RV storage. That is probably why others recommend disconnecting the battery.

I may have lucked out. After two days on a charger, the AGM battery seems to have largely recovered. The voltage is good and it cranks the diesel easily. I’ll keep it on the trickle charger until the system arrives to charge both batteries from the converter.

[Mgtv53]

Originally Posted by Farmer Folly

Yes, this could be an option, but I fail to see why you can’t charge both sets of batteries when attached to house power.

Mercedes sprinters doesn’t allow that . How ever I used 14 gage wire to a 12 volt cigarette outlet that’s not controlled by the ignition it’s on all the time, I plug it in some times

[alajeu]

Originally Posted by paulwadley

Farmer Folly

I had my dealership install an emergency battery jump start from the coach batteries to the chassis battery so if my chassis battery were dead, I could add a charge from the coach batteries to "jump" start the chassis battery. You have to add a solenoid to the circuit between the two battery setups and the switch. If that is what you are looking to do. It has saved me a few times in the past. I also have a 100 watt solar panel on the roof connected to my coach batteries.

Paul

Doesn't your dash have an emergency start button? Just hold down the button and turn the key. I have used it several times with success
Alajeu

[16ACE27]

Originally Posted by alajeu

Doesn't your dash have an emergency start button? Just hold down the button and turn the key. I have used it several times with success
Alajeu

His coach is on the Sprinter chassis, so, No.

[paulwadley]

For reasons unknown, Thor chose not to install an emergency start switch to the coach batteries. I heard it was actually a Mercedes Benz issue. However back in 2015 I bought a 2016 Winnebago ERA Class B which is built on the same Mercedes Benz Chassis that had an emergency start switch wired in by Winnebago. I talked to my dealership service manager where I bought my 2018 Thor Siesta 24SS about adding that switch. He told me that Thor is not allowed to add it because of an issue with Mercedes Benz. I had him look out on their new sales lot for a Winnebago and he discovered it had the emergency start switch installed. He just ordered the same switch from Winnebago and installed it on my Thor Siesta. I have had no issues with it. It works whenever I need it.

Paul

[Captbly]

I too have a chassis battery that runs down from a gremlin drawn from the chassis wiring on my recently purchased of a 2014 Citation. Saw on the internet to install a Xantrax Echo charge. It connects the house positive to the unit and out to the postive to the engine battery. When the engine battery reaches 90% charge it tunes off, and will not come on if the house bank is more than 13 volts. I just put it on and seems to be perfect. If shore power is off, can always run gen set to recharge everything.
Captbly

[Bob Denman]

Welcome to the forum!
Where did you get that Echo Charge?

[Mgtv53]

Originally Posted by Captbly

I too have a chassis battery that runs down from a gremlin drawn from the chassis wiring on my recently purchased of a 2014 Citation. Saw on the internet to install a Xantrax Echo charge. It connects the house positive to the unit and out to the postive to the engine battery. When the engine battery reaches 90% charge it tunes off, and will not come on if the house bank is more than 13 volts. I just put it on and seems to be perfect. If shore power is off, can always run gen set to recharge everything.
Captbly

When I have my Motor home plugged in I use a automatic charger from 120 volt outlet to 12 volt outlet that is not controlled by ignition, it is on all the time

[Farmer Folly]

Originally Posted by alajeu

Doesn't your dash have an emergency start button? Just hold down the button and turn the key. I have used it several times with success

Alajeu

No. Would be nice though. Guess Thor saved money by not including this nice feature. Maybe Mercedes wouldn’t let them.

[Bob Denman]

Originally Posted by Farmer Folly

No. Would be nice though. Guess Thor saved money by not including this nice feature. Maybe Mercedes wouldn’t let them.

That's just about what happened...
MB used to allow it; but no more...

[petefoss]

Me too. Easy solution when plugged in. I've also thought about using the inverter to power the chassis maintainer when I add solar to maintain the coach batteries while boondocking.

Originally Posted by Mgtv53

When I have my Motor home plugged in I use a automatic charger from 120 volt outlet to 12 volt outlet that is not controlled by ignition, it is on all the time

[Pete'sMH]

Originally Posted by petefoss

Me too. Easy solution when plugged in. I've also thought about using the inverter to power the chassis maintainer when I add solar to maintain the coach batteries while boondocking.

Even easier, use this and your chassis battery will be charging anytime your house batteries are. Super simple to hook up.

http://www.lslproducts.net/ALS_Overview_Page.html

[taylorbob1]

Originally Posted by Pete'sMH

Even easier, use this and your chassis battery will be charging anytime your house batteries are. Super simple to hook up.

AMP-L-START Starting Battery Charger/Maintainer - Overview Page

This is the answer for those rigs without a BIM.

I used a similar “combiner/maintainer” just like this on my sailboat

While the house battery (or starting battery, in the case of my boat) is being charged, this contraption “steals” some of the current from one and gives to the other with simple DIY wiring.

[Edensob]

On my Mercedes 24TF (remember the battery is under the interior center hump floor) I wired in a Battery Tender to the chassis battery, ran the wiring under the floor carpeting, and plugged it into the 120 volt outlet behind the drivers seat. I also keep the MH powered all the time we are at home so the converter is operating with the "use" switch operated. Keeps the house and chassis batteries charged and everything is contained within the MH with no cord hanging out anywhere. If I ever did need to boost anything while traveling, I carry a NoCo booster. Right or wrong, it works without interconnecting the chassis and house batteries.


A recent reminder from both Paul (thanks bud) and Thor regarding a recall by Mercedes for a power steering hose connection issue has recently been issued. The chassis needs to be service by a Mercedes Dealer for this recall.

[Bob Denman]

That's a great idea!
I've got a waterproof version of the Junior model, and an outlet in the right-side front storage compartment...

[Bob Nodine]

If you want a true Bidirectional Isolate Relay Delay so that each of your chargers, house and alternator, will be protected from overload then you need to install one of these.

https://tinyurl.com/y6hfl3lh

It will monitor the voltage on the active charger battery bank and not connect the other battery bank until that bank is charged. If you merely tie both battery banks together you risk overloading the alternator or house charger. The Blue Sea ML-ACR also has a manual switch that allows you to connect both banks for a boost to start the engine if the chassis battery is dead. This device has a magnetically latching contactor so there is not a continuous battery drain just to keep the contactor closed.

Bob