[MNWC]

I have a split charge relay from my (Numax) van to leisure battery (Hankook 110a)  Its the 2nd leisure battery ive got through in 2 years.
One of three things spring to mine -

1) Maybe the Van battery has had it, its got to be +5years old but still starts the van no problem.
2) The split charge isnt working as it should.
3) The leisure battery is shagged (its reading 11.5v of the power reel)

Can someone tell me how to test both battery's and split relay ??

Regards

[Ched]

When the engine has been running for a few mins measure the van battery voltage. Then measure the 2nd battery, it should be close to van battery voltage as the split charge should have kicked in. Now switch off the engine. Measure voltage of van battery. Now check 2nd battery. If it's lower then it either needs charging or is on it's last legs. If it's voltage is similar to van battery let it rest for an hour or so (nothing pulling power) and test again. If fully charged it should be about 12.7v.
I don't know if you know but taking a lead acid battery below 50% of it's charge will drastically reduce it's life. 50% is about 12.1v (rested).
11.5v is about 10% capacity so it's probably beyond recovery.
My guess is you don't do many miles and run the pump and elec reel of a single battery. I guess it will gradually go below  50% capacity and will die quite quickly. If you want a battery to last longer then you need to keep it above 50% charge. To do that you might need to either have 2 batteries or charge each night.

[MNWC]

When the engine has been running for a few mins measure the van battery voltage. Then measure the 2nd battery, it should be close to van battery voltage as the split charge should have kicked in. Now switch off the engine. Measure voltage of van battery. Now check 2nd battery. If it's lower then it either needs charging or is on it's last legs. If it's voltage is similar to van battery let it rest for an hour or so (nothing pulling power) and test again. If fully charged it should be about 12.7v.
I don't know if you know but taking a lead acid battery below 50% of it's charge will drastically reduce it's life. 50% is about 12.1v (rested).
11.5v is about 10% capacity so it's probably beyond recovery.
My guess is you don't do many miles and run the pump and elec reel of a single battery. I guess it will gradually go below  50% capacity and will die quite quickly. If you want a battery to last longer then you need to keep it above 50% charge. To do that you might need to either have 2 batteries or charge each night.

Thanks Ched
Ill do all those things tomorrow and let you know the results...
Might only do 2 or 3 miles some days... Correct the battery runs both pump and reel, probably clean between 10 and 15 houses per day..

[Ched]

My guess is then that you are not putting back enough charge in your battery each day to keep it above 50%. So you are killing the battery quite quickly. I guess you might need to charge a new battery via the mains maybe each day.

[Spruce]

My van stood in one spot today while I cleaned 4 big houses before rain called a halt to play.

My leisure battery was fully charged over night. My battery monitor informed me I had used 10 amps from the leisure battery cleaning those houses with large conservatories.

My van first started pumping 45 amps into the battery which tailored off to 10 amps by the time I got home 6 miles later and 15 minutes of driving. The alternator had only put back 3 amps into the battery. If I drive back to the same area tomorrow I could charge the battery by another 3 amps. By the time I get to my first house I'm still 4 amps short.

This wasn't a full day's work and I don't have an electric hose reel.

All I'm saying is that it doesn't take long for the charge deficit to mount up. I appreciate a battery with a lower level of charge will accept a faster charge but eventually the glass will be empty.

I made it a policy to 'bench' charge my leisure battery every night in winter and every second night in summer.

Many years ago I read in an Australian auto magazine that it will take 750kms to fully recharge a leisure battery in the back of a motorhome using a split charge relay.

[Spruce]

Its generally considered that when a battery's voltage drops to 10.4/10.5v under load, its flat.

Spring controllers, Varistream controllers and Webasto diesel heaters will automatically switch off when the voltage drops to these levels under load.

I have just replaced my leisure battery. It will be 7 years old in January.  it would deliver enough current to run my pump all day.
But its voltage very quickly dropped to 10.8v when any additional load was added. When the load was switched off the battery voltage immediately recovered to 12.3v. Had I left the battery idle for a few hours that voltage would have probably risen to 12.4 or 12.5v, indicating a half charged battery.

So relying on voltage readings from an old battery doesn't always tell you the whole story. As a battery gets older it looses capacity.
The only way to test a leisure battery is to put a small load on a fully charged leisure battery and monitor its performance over time.

[MNWC]

Findings this morning ;

Van B                                    Leisure B
12.3v                                     11.7v                      Without engine on
14.4v                                     11.7v                      After 10 mins with engine on
12.6v                                     11.7v                      After 1 hour with engine off

Leisure battery now on bench charge
Looks like the split charger is not working ?

[Ched]

Findings this morning ;

Van B                                    Leisure B
12.3v                                     11.7v                      Without engine on
14.4v                                     11.7v                      After 10 mins with engine on
12.6v                                     11.7v                      After 1 hour with engine off

Leisure battery now on bench charge
Looks like the split charger is not working ?

Yep, look at split charge relay.  Double check all connections are tight and if there are any fuses they are all working. You should be able to check voltage input to split charge where the cable attaches to the split charge to double check the Van batt voltage is getting to the split charge.  Some split chargers have an additional ignition controlled wire (thin wire) so it knows when engine running others just measure voltage using thick power wire. Also make sure the earth wire to split charge is OK. Then check the wires from split charge to leisure battery (both +12v and 0V earth).
The Leisure Batt should have come up to 14.4v after the Van batt had come up and the van had been running for 10 mins.
Hopefully the battery will recover but it might not have much useable capacity left even if the voltage comes back up after charge.

[P @ F]

Been there and done it , killed more than a few bats along the way 
It goes on the bench every night now , only exception is good sunny days when the solar setup comes into its own .

[MNWC]

Update   
Noticed that there was no voltage going into the split charger, chased all the wiring back and found a joint that had corroded and virtually broke off !! New connection and working as it should.

No wonder ive got through 2 batterys in 2 years 

Thanks for your help guys 

[Ched]

Update   
Noticed that there was no voltage going into the split charger, chased all the wiring back and found a joint that had corroded and virtually broke off !! New connection and working as it should.

No wonder ive got through 2 batterys in 2 years 

Thanks for your help guys

That's great news. Always good when you can find and fix something.

[Bungle]

Update   
Noticed that there was no voltage going into the split charger, chased all the wiring back and found a joint that had corroded and virtually broke off !! New connection and working as it should.

No wonder ive got through 2 batterys in 2 years 

Thanks for your help guys

What were you doing in regards charging your leisure battery if the split charge wasn’t working?

[MNWC]

Update   
Noticed that there was no voltage going into the split charger, chased all the wiring back and found a joint that had corroded and virtually broke off !! New connection and working as it should.

No wonder ive got through 2 batterys in 2 years 

Thanks for your help guys

What were you doing in regards charging your leisure battery if the split charge wasn’t working?

Bench charging it