Installing a second battery. (1 Viewer)

Jul 5, 2013
11,713
13,681
Tunbridge Wells, Tunbridge Wells, UK
Funster No
26,797
MH
A class
Exp
Since 2013
When I bought my new Hymer the dealer fitted it with a second battery at my request. He just linked them in parallel with all the positive and negative connections going to the one battery. I did not query this at the time because that is how I wired up my two batteries in my previous motorhome and it seemed to work fine.

I have just read the Hymer Manual (I know ..... what a wooze) and they say that all the positive connections should be on one battery and all the negative connections should be on the other one. Is that correct?

They have also left the connections uncovered, which is OK on the original battery which is tucked away, but the new battery is more exposed. I was thinking of replacing the connectors with those plastic covered ones that you press down on to tighten to the battery post. Are these OK, given that I will be running a 2000W inverter occasionally?

Many thanks for all the advice you can give (as long as it is sensible @Dawn B and @DuxDeluxe )
 

pappajohn

LIFE MEMBER
Aug 26, 2007
43,207
48,833
Dark side of the moon
Funster No
172
Exp
Since 2005
Your manual is correct but its not necessary.

Connect pos to pos, neg to neg but take the live feed from one battery and the neg feed from the other.
It is still 12v but evens out the load on both batteties.

Works best for large battery banks.....4 or more..... but makes little difference for just two batteries.
 
Apr 27, 2008
11,794
13,956
Eastbourne East Sussex
Funster No
2,327
MH
Hymer low profile
Exp
Since 1972
As long as the cables joining the two batteries are thick enough, and if you're potentially drawing 200A they need to be thick, the way you have them wired is fine. Mine are wired like this and I'm sure many others are also. Make sure any terminals you fit are up to the job of carrying the current.

Subscribers  do not see these advertisements

 
OP
OP
peterc10
Jul 5, 2013
11,713
13,681
Tunbridge Wells, Tunbridge Wells, UK
Funster No
26,797
MH
A class
Exp
Since 2013
As long as the cables joining the two batteries are thick enough, and if you're potentially drawing 200A they need to be thick, the way you have them wired is fine. Mine are wired like this and I'm sure many others are also. Make sure any terminals you fit are up to the job of carrying the current.
The cables they have fitted are thin and they have fitted a 20A fuse in the positive connection. But then I never told them I would be fitting an inverter! So I know either way I have to replace the connecting leads with 25mm stuff, it is just whether I should just replace like with like, or switch one of the sets of connection leads (+ or -) to the other battery.
 

pappajohn

LIFE MEMBER
Aug 26, 2007
43,207
48,833
Dark side of the moon
Funster No
172
Exp
Since 2005
If you intend running a largish inverter I would rewire it as it is....pos one battery and neg the other.
I didnt realise an inverter was involved.
 

Lenny HB

LIFE MEMBER
Oct 18, 2007
52,715
147,684
On the coast in West Sussex
Funster No
658
MH
Hymer B678 DL
Exp
Since 2008 & many years tugging
As you are going to be drawing high current forget about the quick release battery terminals, they are made of lightweight pressed steel.

Subscribers  do not see these advertisements

 
Jan 28, 2008
10,104
18,260
Dovercourt, Harwich, UK
Funster No
1,353
MH
Renalt burstner
Exp
7 years campers before that
i was going to say we had snap down connectors and they were a pain for falling of

Subscribers  do not see these advertisements

 
Oct 20, 2013
5,299
12,807
South Norfolk
Funster No
28,653
MH
C Class
Exp
Yes
When I bought my new Hymer the dealer fitted it with a second battery at my request. He just linked them in parallel with all the positive and negative connections going to the one battery. I did not query this at the time because that is how I wired up my two batteries in my previous motorhome and it seemed to work fine.

I have just read the Hymer Manual (I know ..... what a wooze) and they say that all the positive connections should be on one battery and all the negative connections should be on the other one. Is that correct?

They have also left the connections uncovered, which is OK on the original battery which is tucked away, but the new battery is more exposed. I was thinking of replacing the connectors with those plastic covered ones that you press down on to tighten to the battery post. Are these OK, given that I will be running a 2000W inverter occasionally?

Many thanks for all the advice you can give (as long as it is sensible @Dawn B and @DuxDeluxe )
I was sorry to hear about your accident :whistle:
 

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!

Log in

Already a member? Log in here.

Latest journal entries

Funsters who are viewing this thread

Back
Top