Chassis Batteries - Help Please

[bowpulpit]

Purchased 2 months ago a 2016 Ventana LE 4037 on Freightliner Chassis.

After starting the engine the display panel always reads "Low Battery".

Checking the Magnum panel, chassis batteries reads 12.8 volts (house batteries at 13.6). I used a volt meter on the both chassis batteries and they each read 13.6 volts.

Today for the first time after starting the engine, the dash volt meter cycled a couple times down to about 8 volts which caused the "Low Battery" readout to display momentarily then it would bounce back up to about 13 volts. It did this 2-3 times then stopped.

Have no clue why I can check battery volts at 13.6 then get "Low Battery" warnings.

Anyone have a idea what to look for.

Thanks

 

[Neal]

Completely normal, it's the high voltage spike at startup, it can be ignored. FL should have programmed this alert out as it causes everyone concern.

 

[bowpulpit]

Completely normal, it's the high voltage spike at startup, it can be ignored. FL should have programmed this alert out as it causes everyone concern.

Thanks Neal....making sure I understand.....the low volatge warnings I get at every startup is normal?. Also, today for the first time the panel volt meter cycling between 8 and 13 volts 2-3 times......this is normal too?

This coach is my first diesel rig and I'm still learning.

Thanks

 

[Neal]

I’m not sure about the voltage you’re observing. It’s not something I ever check at start.

 

[bowpulpit]

I’m not sure about the voltage you’re observing. It’s not something I ever check at start.

Thanks Neal.....The instrument panel LCD display under the gages is where is see the "Low Battery" warning when I start the engine. This warning caused me to check the Magnum panel and the chassis batteries themselves.
So I'm still trying to determine of the "Low Battery" warning is normal?

 

[NWIP]

If these are the original chassis batteries there is a possibility that they are close to there useful life. It is normal after the coach has sat to get the low batt warning on startup. Normally only get the warning after sitting awhile. Has the coach been plugged into shore power?

 

[Neal]

Low voltage warning on engine start is NORMAL and can be ignored.

 

[VTPete]

My2017 Ventana LE is the same, always with the low battery drama! As I recall there was a firmware update that Freightliner issued early in 2018 and was applied to my coach. it was supposed to fix the problem but it didn’t.

 

[Kevin D Pem]

I agree with @Neal after start the batteries will reflect the hit they get starting the engine. The regulator will try to keep the batteries at 14.4 on most vehicles no matter what the power plant is. Your indicator reflects this hit and should clear after the generator gets the voltage up to normal. At rest the batteries should read 12.67 fully charged having set for 24 hours. It is fully possable that the regulator is a three stage regulator in that case 13.8 is likely float charge and bulk charge would be 14.4. Of course that is a 12v system.

 

[bowpulpit]

Thanks Everyone for your input. I've learned from your responses and that of others that the Low Battery warning at start up on my Freightliner chassis is normal.

 

[Chuggs]

If you watch the dash, there is a yellow light which illuminates when you first turn the key. Diesels will have glow plugs or grid heaters. So, depending on temperature they may run a little or a lot. They put a nice draw in the batteries. Then you hit the starter...and that puts a huge drain in the batteries. So, the dash unit reads the battery voltage after start as LOW. They will recover, and when the alternator gets spinnin, you’ll probably see the dash voltage near 15v.

The 12.8v chassis reading, I am assuming on the digilevel display? That is pretty indicative of a chassis battery getting no charge...and has been resting. When you measured 13.6 at the chassis battery, it is telling you something different now. A charge is getting to them. If you have engine running...alternator —- if you don’t have engine running and the shore power is connected...you are sharing the Inverter Charger with the chassis thru the bi-directional relay. As a matter of fact...although not proof positive...but a high likelihood exists...if you look at the digilevel and both the House and Chassis are reading the identical voltage...mmmm the bi-directional relay has closed and both banks are joined and sharing a charge source.

The engine warmup and engine starter are probably why you are getting the swinging voltage for the chassis, engine lift pump for pressurizing diesel fuel to the rails. There is a good reason we have two group 31 starting batteries with 1000 Cold cranking Amps. The diesel sucks power for startup. Then a 240A alternator to replenish and keep things powered. There is a long wire run from the rear to the dash...the stuff in the back is going to hoard the voltage...but as long as your engine fires up without hesitation, and the chassis voltage recovers quickly after start up...you are doing okay!