Help, Starter battery issue.

[Phantom]

I went to start the MB Sprinter MH today and found that the 110 Amp starter battery was flat. This was rather surprising as it is normally kept topped up by solar and leisure batteries which appear still fully charged. So not sure if the issue is the starter battery itself, charge not going in, a current drain, or a combination of these?

The starter battery was showing 12.5v but when ignition turned to second position dropped to about 7v with dash lights flicking on and off to a clicking relay. When also hooked up to a second battery all seemed normal though just not enough power to spin the motor over enough. I'm charging the starter battery overnight so will see how it is tomorrow.

The set up has worked just fine ever since we bought the MH nearly 2 years ago. It has a 120w solar panel and the controller visually seems to be working okay. There is a Van-bitz battery master fitted to the leisure batteries that is supposed to send excess charge to the starter battery. I've checked the fuses on the wires connected to the starter battery and they are all okay though not sure if there are any related others anywhere? The MH has only been stood for 1 month since our last trip with a small draw from the alarm so it seems a bit odd really, any ideas what the issue could likely be?
Here's a pic of the starter battery wires. I guess that the fuses on the right (yellow 10Amp & Green 30Amp) are where the starter battery should get it's charge from the leisure side?

 

[wildebus]

TBH, sounds like a faulty battery with a bad cell or two.
My Starter Battery on my LT (aka Sprinter) did exactly the same thing when I bought it. As soon as the weather got colder, it died on the first key turn despite appearing to be fully charged. Got a new battery and never had an issue since

 

[trevskoda]

You will need to test after fit new battery,first thing i see is a corroded tray,id have that out and shotblasted and epoxy coated.buy a varta/bosch silver power frame battery,you wont regret doing so.

 

[Phantom]

TBH, sounds like a faulty battery with a bad cell or two.
My Starter Battery on my LT (aka Sprinter) did exactly the same thing when I bought it. As soon as the weather got colder, it died on the first key turn despite appearing to be fully charged. Got a new battery and never had an issue since

I think you are right, I've just spotted the battery date and it's over 7 1/2 years old!

 

[Phantom]

You will need to test after fit new battery,first thing i see is a corroded tray,id have that out and shotblasted and epoxy coated.buy a varta/bosch silver power frame battery,you wont regret doing so.

I'm just looking at batteries now, will see what I can get locally tomorrow. But will make sure that there is not another problem that caused it to go.

 

[trevskoda]

I'm just looking at batteries now, will see what I can get locally tomorrow. But will make sure that there is not another problem that caused it to go.

The silver power frame batts are the best and will hold full power for 5 years,dont settle for anything less,should be about £110 ,good luck.

 

[Okta]

When batteries sulphate they lose capacity. The bits of each cell that are not sulphated behave as normal i.e. they will charge up to the full voltage but the voltage can drop off rapidly because what you think of as a 110Ah battery is possibly holding only a fraction of that, say 30Ah. Could be a failed cell but symptoms (12.5v before trying to start) suggest to me sulphation. However whatever the cause it sounds like the battery has had it but it might make a difference where you look for causes. Sulphation can be caused by under charging so I would also be checking that the alternator charging is delivering a proper voltage and charge.

 

[trevskoda]

When batteries sulphate they lose capacity. The bits of each cell that are not sulphated behave as normal i.e. they will charge up to the full voltage but the voltage can drop off rapidly because what you think of as a 110Ah battery is possibly holding only a fraction of that, say 30Ah. Could be a failed cell but symptoms (12.5v before trying to start) suggest to me sulphation. However whatever the cause it sounds like the battery has had it but it might make a difference where you look for causes. Sulphation can be caused by under charging so I would also be checking that the alternator charging is delivering a proper voltage and charge.

And thats why the silver power frame last much longer,the frames dont break up or sulphate for many years.

 

[RV2MAX]

You can get battery over night/ next day online from say Battery Megastore usually a lot cheaper than local factors . Another one is Tayna Batteries

 

[St3v3]

I guess that the fuses on the right (yellow 10Amp & Green 30Amp) are where the starter battery should get it's charge from the leisure side?

One could be for your fridge, the other for split charge.

 

[Phantom]

After charging the battery overnight the MH was all good again but I still replaced it with a Varta as it was nearly 8 years old.

 

[Phantom]

One could be for your fridge, the other for split charge.

You're probabaly right as the one with 10A fuse has power from leisure/solar. I'm slowly figuring out what all the multitude of fuses are for which is not a bad thing.

 

[Frogman]

Had a similar problem free camping in the Algarve. Switched on one morning, got clicks and clunks and just about every warning light. Meter said 10 volts. 2 hours later and some sunshine for the solar and it started! Friend nearby had replaced his and sent me to a battery shop . . . who didn't have one, so in desperation went to Merc main dealer. The Merc genuine part was cheaper!

 

[Nosmo king]

I had to replace both batteries the other week, then I found out 2 things, first I think this site has a discount arrangement with a battery supplier ?, AFTER I brought the 2 120ah batteries a mate told I should have brought a Leicestercn battery charger (from Amazon) as they bring batteries back from the dead, I brought one and it has brought my motor bike battery back from the grave.