Chausson Best of 10 battery system

[Engtech]

We recently bought a Chauson Best of 10 which has a roof mounted solar panel with 2 leisure batteries under the passenger seat.
On our first trip away our first overnight stop was a Britstop so no electric but we weren't worried as we had 2 leisure batteries and a solar panel.
Anyway after parking up with fridge running nicely on gas settled down to watch tv after taking the dog for a walk and were surprised that after a couple of hours the low battery warning was flashing, leisure battery showing about 50%! After a little puzzling started the engine and ran it for 10 minutes and leisure battery charged up.
When getting ready for bed went to lower the bed and noticed battery warning again, it wouldn't operate the bed lowering system so ran the engine again to give it a boost, lowered the bed and turned in.
The dealer has tested the batteries, which were newly fitted at handover, and pronounced them good so leaving me totally puzzled.
Any thoughts?
Graham

 

[Cush]

If a 10 minute engine idle significantly charges the batteries then my guess is that they are not great condition. Without a day on ehu and them being full it would be hard to draw any conclusions, sorry. They may not have been fully charged at the start of the trip?

do you have any voltage readings from full sun? Any lights on your solar charger? Pics may help

hope you get some answers

 

[Lenny HB]

The dealer has tested the batteries, which

Why would the dealer test the batteries if they were new, that doesn't sound right.

Also when dealers test batteries they usually do a CCA test which is a starter battery test which is pointless for a leisure battery.

I suspect they weren't new batteries and have had it.

If you don't have a B2B fitted you would need to drive all day to recharge flat batteries.

 

[Engtech]

If a 10 minute engine idle significantly charges the batteries then my guess is that they are not great condition. Without a day on ehu and them being full it would be hard to draw any conclusions, sorry. They may not have been fully charged at the start of the trip?

do you have any voltage readings from full sun? Any lights on your solar charger? Pics may help

hope you get some answers

Full sun I got 38v from the panel and 13.8v to the batteries so the panel is working as it should. The panel goes to the batteries via a Sargent MPPT unit.

 

[Engtech]

Full sun I got 38v from the panel and 13.8v to the batteries so the panel is working as it should. The panel goes to the batteries via a Sargent MPPT unit.

Van was on EHU for at least 24hrs before we left home so should have been fully charged then about a 4 hour drive as well.

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[Engtech]

Why would the dealer test the batteries if they were new, that doesn't sound right.

Also when dealers test batteries they usually do a CCA test which is a starter battery test which is pointless for a leisure battery.

I suspect they weren't new batteries and have had it.

If you don't have a B2B fitted you would need to drive all day to recharge flat batteries.

Dealer tested the batteries after I reported the problems we’d experienced and they weren’t flat when we left home and were showing full when we parked up as I was playing with the panel when we parked up being new fangled with the van. How do you suggest to test leisure batteries?

 

[Lenny HB]

Full sun I got 38v from the panel and 13.8v to the batteries so the panel is working as it should. The panel goes to the batteries via a Sargent MPPT unit.

Voltage from the panel should be between 18 - 22v output from the solar controller should rise to about 14.4v then drop to 13.8v when the battery is charged.

 

[Lenny HB]

Dealer tested the batteries after I reported the problems we’d experienced and they weren’t flat when we left home and were showing full when we parked up as I was playing with the panel when we parked up being new fangled with the van. How do you suggest to test leisure batteries?

Best to test each battery seperatly.

To do a discharge test:-

First charge the battery fully and leave it to settle for an hour then:-
Disconnect all charging methods.

For example if it's a 100a/h battery load it with a 5 amp load and run for 5 hours, this will represent a 25% discharge. (adjust load/time to suit the size of the battery)
Disconnect the load and leave to stand for at least 30 min then measure the voltage.
Repeat the test and you will have discharged the battery to 50%.
You can repeat again then it will be 75% discharged.

 

[Cush]

Voltage from the panel should be between 18 - 22v output from the solar controller should rise to about 14.4v then drop to 13.8v when the battery is charged.

I knew someone would know what to say

 

[Cush]

With the info above I would say they were as fully charged as they could be but dropping so quickly would indicate tome that I need to try new batteries. But thats just me.
is it possible you have something else running off 12v that could be a massive draw?

You should be ok doing the bed with the engine running. But wouldn’t do it long term. Basically your engine alternator is powering the bed.
Cush

edit - if you’re still a free member you may have used up your free posts. Well worth the subs .

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[headlight]

Full sun I got 38v from the panel and 13.8v to the batteries so the panel is working as it should. The panel goes to the batteries via a Sargent MPPT unit.

Isn't 38v an odd voltage from a single panel ?
I wonder if the OP meant 38 Watts as wouldn't 38v suggest 2 panels in series ?

 

[Lenny HB]

Isn't 38v an odd voltage from a single panel ?
I wonder if the OP meant 38 Watts as wouldn't 38v suggest 2 panels in series ?

Not if it's a house panel.

 

[autorouter]

after a couple of hours the low battery warning was flashing, leisure battery showing about 50%! After a little puzzling started the engine and ran it for 10 minutes and leisure battery charged up.

I hope you appreciate just how long it takes to charge a battery. If your two batteries have a capacity of 2 x 100Ah = 200Ah, then 50% of that is 100Ah. If your alternator is supplying 30A (that's optimistic) then it in theory it would take 100/30 = 3.3 hours to take them from 50% to full. In practice the charging process is not more than 80% efficient, so realistically it's more like 4 hours.

In 10 minutes the alternator is producing 30A for 1/6 of an hour, so that's 30/6 = 5Ah, and at 80% efficiency that will put 4Ah into the 200Ah batteries.

As I'm sure you now understand, the voltage of a battery is not a reliable indication of how charged it is. If it's being charged by anything (solar, EHU, alternator) then its voltage will be whatever the charger forces it to. If you remove all charging and loads, and leave it to rest for an hour or two, then the battery voltage will more or less show you how charged it is, from Lenny HB's chart for example. But in a motorhome with solar panels, that's only at night with no loads on, so not very often.

I don't know how much your TV takes, but I'd guess it's about 60W, which works out at 60/12 = 5A. At that rate, a full 200Ah of battery should last 20 hours continuously before it's down to 50%, since 5A x 20 hours = 100Ah. Your batteries are either not fully charged to start with, or totally goosed.

 

[headlight]

Not if it's a house panel.

I was assuming it was a new van and the panel was dealer fitted in which case fitting a house panel would be strange.
I suppose the OP could have fitted a domestic panel or its a second hand van and a previous owner fitted a domestic panel.
I hadn't thought of that.

 

[denisejoe]

With solar you can never be certain of the control panel reading as in the morning the reading will be what the solar is putting into the batteries not what they are charged to.
that's the way I read it ?

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