Chassis battery

[bsedor]

Happy Thanksgiving to all!

Can anyone tell me if my 2016 Grand Tour has a battery tender to keep the chassis battery charged while the van is plugged in?

Bob

[Protagonist]

Originally Posted by bsedor

Can anyone tell me if my 2016 Grand Tour has a battery tender to keep the chassis battery charged while the van is plugged in?

Interstates have a relay called a Battery Isolation Module (BIM). The purpose of the BIM is to isolate the house batteries from the chassis battery when there is a drain on one side but not the other, and to connect the house and chassis batteries together when there is a source of charging voltage from (almost) any source— shore power, generator, engine alternator, but usually not solar because the stock solar panel doesn't produce enough charging current to activate the relay.

So, if you have the van plugged into shore power— and the inverter/charger is turned on so that it can charge the batteries— then the chassis battery will be charged as well. Which is the gist of your question, even if a BIM isn't exactly a "battery tender."

Note however that the house batteries are Group 24s, and the chassis battery is a Group 49, so charging will be less efficient when the house and chassis batteries are connected. The two battery sizes have different amp-hours and cold cranking amps and may be at different charge states when charging begins, so when the house batteries are fully charged, the chassis battery may end up over-charged or under-charged (a Magnum inverter/charger only measures the charge state of the house batteries, not the chassis battery). But it's still better than not being able to charge the chassis battery from shore power.

[Boxster1971]

Originally Posted by bsedor

Happy Thanksgiving to all!



Can anyone tell me if my 2016 Grand Tour has a battery tender to keep the chassis battery charged while the van is plugged in?



Bob

Happy Thanksgiving to you!
I agree with everything said by Protagonist - with one clarification. Since you have a 2016 with a Magnum inverter/charger it will automatically start charging your batteries when you plug into shore power or start the LP generator. It does not need to be "turned-on".


- - Mike
2013 Lounge EXT on 2012 Sprinter

[Protagonist]

Originally Posted by Boxster1971

Happy Thanksgiving to you!
I agree with everything said by Protagonist - with one clarification. Since you have a 2016 with a Magnum inverter/charger it will automatically start charging your batteries when you plug into shore power or start the LP generator. It does not need to be "turned-on".

Thank you. I keep forgetting about that since I still have a Tripplite with an accessible off switch.

[lewster]

And 2016 models actually have a functioning BATTERY TEMP SENSOR!!!!!!

Will wonders never cease?!?!?!


Lew Farber
RVIA/RVDA Nationally Certified Master Tech
Master Tech Energy Systems, Inc.
AM Solar Certified Installation Center
Lifeline Batteries**Magnum Inverters
541-490-6357

[Land Sailer]

Originally Posted by Boxster1971

Happy Thanksgiving to you!
I agree with everything said by Protagonist - with one clarification. Since you have a 2016 with a Magnum inverter/charger it will automatically start charging your batteries when you plug into shore power or start the LP generator. It does not need to be "turned-on".


- - Mike
2013 Lounge EXT on 2012 Sprinter

So, if I plug into shore power for storage, chassis and house batteries will charge with the Magnum and power switch off?

[Land Sailer]

Originally Posted by Dena m

So, if I plug into shore power for storage, chassis and house batteries will charge with the Magnum and power switch off?

Oh, my Interstate is a 2017.

[Boxster1971]

Originally Posted by Dena m

So, if I plug into shore power for storage, chassis and house batteries will charge with the Magnum and power switch off?

If you are plugged into shore power when stored you don't need to turn OFF the power switch. Just leave it ON and everything will get properly charged.

[wwwtractor]

Has anyone found an acceptable lithium chassis battery replacement LiFePO4 with the highest Amp Hour rating available? So far I see Antigravity(80), Ampere Time(100), and Ionic(125) batteries in the same form factor H8 as the chassis battery.

I have a LiFePO4 400 Amp Hour house battery which has been working fine for over a year but I was thinking that it would be better if I converted the chassis battery to same chemistry. I installed a toggle battery connect switch to get more charging out of the alternator while traveling.

[Boxster1971]

Originally Posted by wwwtractor

Has anyone found an acceptable lithium chassis battery replacement LiFePO4 with the highest Amp Hour rating available? So far I see Antigravity(80), Ampere Time(100), and Ionic(125) batteries in the same form factor H8 as the chassis battery.

I have a LiFePO4 400 Amp Hour house battery which has been working fine for over a year but I was thinking that it would be better if I converted the chassis battery to same chemistry. I installed a toggle battery connect switch to get more charging out of the alternator while traveling.

Probably not a good idea as the alternator and its control circuits are designed to charge Lead-Acid batteries. Of course there might be some lithium batteries with built in controls or a Battery Monitor System (BMS) that would work. You will also have to deal with freezing issues just like your LiFePO4 400AH house battery.

[uncle_bob]

Hi

Not a great idea for a couple of reasons:

1) Charging LiFePO4 below freezing is not a good thing. Even with heaters, you still stop charging pretty close to freezing. Travel somewhere cold and that's an issue.

2) The normal LiFePO4 cells have very limited max discharge numbers. A starter motor can pull an insane amount of current for pretty brief periods of time. That's not a good combination.

3) Your LiFePO4 ( or any other chemistry lithium) is going to have a BMS on it. The starter motor also feeds some pretty crazy spikes back towards the battery. Even if the battery is ok with them, the MOSFET's in the BMS are not likely to be happy ....

4) Lead Acid batteries are a bit more tolerant of "non-ideal" charging circuits. Getting a typical alternator to do what a lithium needs it to do ... not so easy. Yes, you can put on a second alternator and a full up control on it .... yuck ....

Yes, you could keep going with this list ....

Bob

[Titus]

Late at night and I can't pull up the floor panel and look, so I'll ask the forum:
What type of chassis battery is the stock battery? Lead acid? AGM? etc. Somewhere I read that you needed to replace is with a special MB chassis battery, but what is so special about it (other than the price)?

[Foiled Again]

Originally Posted by Titus

Late at night and I can't pull up the floor panel and look, so I'll ask the forum:
What type of chassis battery is the stock battery? Lead acid? AGM? etc. Somewhere I read that you needed to replace is with a special MB chassis battery, but what is so special about it (other than the price)?

Still have the 2013 Interstate.

[Alex AVI]

Originally Posted by wwwtractor

Has anyone found an acceptable lithium chassis battery replacement LiFePO4 with the highest Amp Hour rating available? So far I see Antigravity(80), Ampere Time(100), and Ionic(125) batteries in the same form factor H8 as the chassis battery.

I have a LiFePO4 400 Amp Hour house battery which has been working fine for over a year but I was thinking that it would be better if I converted the chassis battery to same chemistry. I installed a toggle battery connect switch to get more charging out of the alternator while traveling.

WWWTRACTOR - LiFePO4 starter batteries have existed for some time now, starting in the PowerSports industry to now supporting automotive applications, in almost all common sizes. IMHO the question is what would be "acceptable" to you?

1. CCA specs seem to be mutually exclusive from their AH specs i.e. the higher CCA's have lower AH. I am not a battery engineer so I do not know if this is inherent in these types of lithium starter batteries.

2. They cost >10x compared to an SLA with identical CCA. So an 850-1,000 CCA LiFePO4 could be >$1,200.

3. They all have the cold weather charge & discharge cutoffs that previous posters mentioned. A very limiting factor depending on where you live.

4. They may need additional electronics (i.e DC-DC chargers) beyond their built-in BMS to limit alternator charging when using with HO alternators (read Sprinter 220A). This is related to #1 since the lower the AH, the lower you need to limit your alternator charge current.

If all 4 above are "acceptable" to you, then there's plenty of options.

[uncle_bob]

Hi

Diesel engines are a whole other world compared to a small gas engine the it comes to starter batteries...... they crank longer and harder, especially in the cold.

Bob