Lithium battery down to 11.3v

jeddy

jeddy

Joined
Mar 12, 2021
Posts
92
Likes collected
87
Location
Wales
Funster No
79,695
MH
Autosleeper Malvern
Exp
Since 1999
Picked up my Autosleeper Malvern a month ago fitted with new lithium battery. On Saturday I received an alert from AS Monitor that battery was discharged. Checked van and down to 11.5v. Ran engine and got back to 12.4v.
This morning down to 11.3v. I cannot think of anything drawing this much from the battery.
Am I right in thinking that 90% discharged should still give me 12v?
The dealer replaced the lead acid battery with the new lithium. Is it possible that other necessary changes were not done and could have led to this problem?
 
jeddy said:
Picked up my Autosleeper Malvern a month ago fitted with new lithium battery. On Saturday I received an alert from AS Monitor that battery was discharged. Checked van and down to 11.5v. Ran engine and got back to 12.4v.
This morning down to 11.3v. I cannot think of anything drawing this much from the battery.
Am I right in thinking that 90% discharged should still give me 12v?
The dealer replaced the lead acid battery with the new lithium. Is it possible that other necessary changes were not done and could have led to this problem?
Click to expand...
What chargers do you have fitted ?
 
Don’t know what is fitted. The control unit is Sargent EC700

IMG_2637.jpeg
 
jeddy said:
Don’t know what is fitted. The control unit is Sargent EC700

View attachment 841096
Click to expand...
Someone will be along soon to give you suggestions but as Peavy said it may be worth asking the dealer if he set up the charger correctly, Lithium battery’s have a slightly different charging profile to Lead acid.

Subscribers  do not see these advertisements

 
A lithium battery has a very flat voltage profile and from around 10% - 90% the voltage stays the same.
So you may have got it up to 12%.

I don't know off the top of my head but I think around 20% it hits 13V and stays there pretty much up to 80/90%.

Here is a cell voltage profile (multiple by 4 for a 12v battery)

1701766485221.png
 
A fully charged lithium battery should not discharge in a month unless there is something taking current from it. What was left switched on and what current does it draw?
 
StillGoing said:
A fully charged lithium battery should not discharge in a month unless there is something taking current from it. What was left switched on and what current does it draw?
Click to expand...

Do we know the battery was fully charged or the level of charge when fitted a month ago?
 
The dealer will most likely have replaced the leisure battery with lithium, it is most likely your conventional cab battery which is discharging and you are receiving a warning about, the leisure battery, being lithium, is possibly still near 100%. if the above is correct a battery master between the two would resolve your issue
 
Running the engine to charge the battery will take a good long while to have a significant impact. Unless you've got a very beefy B2B?

Subscribers  do not see these advertisements

 
In our van you can switch off the control panel but there is still a draw (quite normal I believe) so the OP may think everything is switched off but even a few amps a day adds up over a month ;) the only way to stop ours drawing amps is to isolate the battery (y)
 
I have the same unit in my autocruise, its for lead acid only according to Sargent, the mains charger mounted elsewhere is the same.
Both only charge at 15amps max.
 
Are you referring to your vehicle battery, or your leisure battery? If the latter, you’ll need to run the engine for a long time to put anything worthwhile into it.

Ian
 
The AS Monitor you mention I think is a Sarget unit and if it only reports voltage and it's lead acid batteries it's probably meaningless.
Does the battery you had fitted have a Blutooth BMS so you can see the actual state of the battery?

Subscribers  do not see these advertisements

 
A quick Google reveals that one screen of the Sargent unit displays info on both batteries so you can see what the current position is. A full manual can be downloaded HERE
 
Lenny HB said:
The AS Monitor you mention I think is a Sarget unit and if it only reports voltage and it's lead acid batteries it's probably meaningless.
Click to expand...
The AS Monitor is an AutoSleepers unit, from Sargent. There is a website for it, and a manual:
The manual is linked at the bottom of the page.

If the EC700 unit is off, the only alerts are the alarm and the leisure battery level. When it's on, you can see and control lots of other items.
 
Okay. Cannot think of anything switched on. Just visited van in storage. Panel flashing and error code.

IMG_2642.jpeg
 
Went for 20 mile drive.

IMG_2647.jpeg IMG_2646.jpeg

Subscribers  do not see these advertisements

 
Error now replaced with incorrect time suggesting loss of battery. Batteries now charged. Little current being drawn. In fact less than solar putting in.
 
jeddy said:
Don’t know what is fitted. The control unit is Sargent EC700
Click to expand...
Do you have any means of charging it? Solar panels, or mains hookup? Many motorhomes seem to run their batteries down in a month or so, it's not unusual. Most either have solar panels to keep it topped up, or hook up to the mains: permanently, or every week or so on a timer, or just plug in every month or so. Or take it for a good long drive regularly to top it up. It will take several hours to fill up a fairly flat battery, whatever the voltage reading says. And from what I hear, starting the engine and leaving it ticking over cold is not a good idea for newer engines with DPF etc.
 
I’m pretty certain the battery has discharged to a high degree. Should not happen in a month especially with solar panel doing something.
My old van could sit for weeks with no issues.

Subscribers  do not see these advertisements

 
I wouldn't get tied up in knots over charging profiles at this stage. You may not have a system which is properly matched for Lithium but it should charge them, even if the charging voltages aren't quite right.

As others have said if the leisure battery is dropping below 12 volts with it sat still then there is a fault somewhere. This is what you need to concentrate on. I would ring the dealer who fitted it and see if they are helpful in tracing the cause. Alternatively, get out the multimeter and see if there is any drain of current when solar isn't working - disconnected or at night.
 
I would lay a bet that said solar panel is producing little and is set to lead acid profile. Therefore not topping up the lithium battery correctly. Lithiums are not a simple drop in replacement. The same with the mains charger
 
What radio have you got, pioneers draw a lot of power when in standby.
 
TheBig1 said:
I would lay a bet that said solar panel is producing little and is set to lead acid profile. Therefore not topping up the lithium battery correctly. Lithiums are not a simple drop in replacement. The same with the mains charger
Click to expand...
I think the main issue is a new lithium battery should not fully discharge in four weeks with no load. One of the main advantages is slow rate of discharge. Another is ability to work down to as much as 90% discharge.
Solar panels kept my previous van fully charged in winter storage.
In 25 years of motorhoming and 5 vans, I’ve never experienced anything as bad as this with a leisure battery.
I cannot find anywhere to change charging profile.
Just to add to my worries I’m due to set off for Spain on Monday.
 
MichaelT said:
What radio have you got, pioneers draw a lot of power when in standby.
Click to expand...
Hopefully it is switched off when ignition is off.

Subscribers  do not see these advertisements

 

Join us or log in to post a reply.

To join in you must be a member of MotorhomeFun

Join MotorhomeFun

Join us, it quick and easy!

Join us

Log in

Already a member? Log in here.

Latest journal entries

Back
Top