# Charging batteries



## j20ands10 (Sep 16, 2010)

I have been advised to remove my twin battery setup and charge them using a battery optimiser such as a CTEK Multi XS 3600 as the inbuilt unit will never get 2 110ah batteries to 100% charged.

I have looked around on the forum and have found fitting guides but no referance to charging.

Maybe someone with more battery knowledge will be able to help me and answer my questions below.

1 Do I have to disconnect the batteries from the MH before charging?
2 Do the batteries have to be disconnected from each other before charging?
3 Surly if I charge them both separately they could end up at different voltages/charged states is this a problem.?

4 Would I be better just running them separately and fitting a change over switch? Which seems to be common practice on boats?


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## geraldandannie (Jun 4, 2006)

j20ands10 said:


> I have been advised to remove my twin battery setup as the inbuilt unit will never get 2 110ah batteries to 100% charged.


Who advised you? And what is your current setup? Do you have a built-in, mains charger?

I have twin, 110 A-hr batteries, and wouldn't dream of charging them by any other means that the built-in charger.

Gerald


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## clive1821 (Mar 27, 2010)

there are many options and views.... I for one charge (and Gerald)upto 13.8 volts as per the main battery, the charge from the alternator is slightly higher to push up the batteries to 14.4 volts which is the max boost voltage and then returns to about 13.4volts for float charging.... so to answer the question just leave things alone if alls working well leave alone. Batteries will last around 3 years and anything more than that its a bonus  with that set up, (internal mains charger and vechicle alternator) plus the solar panels!! my van lasts about 3 days and with a lot of demarnd from them over and above normal use....


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## j20ands10 (Sep 16, 2010)

*current setup*

2 x 110 AH Batteries
1 x Mains charger which charges
1 x MH Alternator also charges when the cab is running.

It was a passing comment that at standard mains charger fitted to a MH will never get 2x110's fully charges and should charge them a few times a year with a good quality battery optimiser.

Everything is working as far as I can tell we have just done 3 days 2 nights with fridge and lights, with only a 20mile drive on day 2 ended on about 60% charge - Based on the voltage chart I found on here.

I always put the batteries on charge via the mains charger 24-48 before we go away also heat the water and cool the fridge during the last few hours 

I will be home in a short while and will get the specs on the charger, maybe that needs uprating?


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## trevorf (May 16, 2005)

I agree with the guy who advised you. A standard built in unit is a compromise between a power supply and a charger. A multistage charger like the CTEK will do a much better job at looking after your batteries. I have permanently wired in a CTEK3600 into my own van to look after the 2X85AH lead acid batteries which have lasted 6 years and still look good on my digital load tester.

To answer your questions:-
1. No you do not have to disconnect just turn off any sensitive 12V equipment whilst charging at 14.7V
2. Leave them linked together so they both receive equal charge and discharge equally.



Trevor


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## j20ands10 (Sep 16, 2010)

trevorf - would i connect the neg to one battery and the pos to the other?

I was thinking of fitting an isolator between the two and only charging one at a time but going off what you have said sounds like it will be fine. My concern was if one of the cells whent down it would pull both batteries down. Plus the ctek3600 is only rated for batteries from 1.2 to 120 Ah - your setup is 170 Ah and min is 220 Ah

I have just checked both are reading 12.82v so now fully charged after a 1hr drive home and then 4 x 5mile trips to and from work. (the MH has sat on the drive for the last 4 hrs so will take this reading as been the settled one) :?:

The charger is a Volta Intelligent 3-Stage 18 amp Leisure Battery Charge
http://www.bridgendcamping.co.uk/default.aspx?CategoryID=54&ItemID=VOL3ST


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## trevorf (May 16, 2005)

> trevorf - would i connect the neg to one battery and the pos to the other?


Your batteries should be connected pos-pos and neg-neg anyway so it does not make any difference 



> your setup is 170 Ah and min is 220 Ah


It will just take a little longer to charge yours :wink:

If the Volta charger is your standard one then it looks pretty good, I would stick with it. Many standard chargers are not "intelligent 3 stage" like that one.

Trevor


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