second battery help

  • HTML tutorial

lucky_strike

Rank III

Contributor I

hey all,

I have a well built 81 k5 Blazer with a SBC 350. I would like to run a second battery...but don't see the need for isolators and doohickeys. it will be used for KC lights and winch pulls. is it okay to just run a deep cycle parallel with my existing battery?
 

oldmopars

Rank V
Launch Member

Member III

2,865
Selah Wa
First Name
Scott
Last Name
Solomon
Member #

20486

Running 2 different types of batteries is not recommended. At least not parallel all the time. The batteries have different needs and it may cause a shorter life of both.
They can be hooked together while charging, but it is best if while not charging that they are isolated. You can do this with a good relay, not an isolator.
Just put a switch on the dash to operate the relay. It would be best to have 3 options, on with the ignition, on all the time, and off.
This way you can charge with the engine running, you can use it as a jumper battery, use it to assist the main battery while winching, or disconnect it completely in case something is wrong with the system, or other reasons.
If you want more details, I ma sure we could create or find a diagram.
 

KonzaLander

Rank VI
Member

Traveler II

3,402
Junction City, Kansas, USA
Member #

15814

Ham/GMRS Callsign
KE0EBF
@lucky_strike - Based on your use, I think a single quality AGM battery would suite your needs.

Running 2 different types of batteries is not recommended. At least not parallel all the time. The batteries have different needs and it may cause a shorter life of both.
They can be hooked together while charging, but it is best if while not charging that they are isolated. You can do this with a good relay, not an isolator.
Just put a switch on the dash to operate the relay. It would be best to have 3 options, on with the ignition, on all the time, and off.
This way you can charge with the engine running, you can use it as a jumper battery, use it to assist the main battery while winching, or disconnect it completely in case something is wrong with the system, or other reasons.
If you want more details, I ma sure we could create or find a diagram.
You pretty much described my dual battery setup. The only difference is I have voltmeters to check up on the batteries.

I did a rough write up of my install. No complicated systems or doohickeys. Sharing the link for @lucky_strike
 
Last edited:
  • Like
Reactions: oldmopars

oldmopars

Rank V
Launch Member

Member III

2,865
Selah Wa
First Name
Scott
Last Name
Solomon
Member #

20486

@lucky_strike - Based on your use, I think a single quality AGM battery would suite your needs.


You pretty much described my dual battery setup. The only difference is I have voltmeters to check up on the batteries.

I did a rough write up of my install. No complicated systems or doohickeys. Sharing the link for @lucky_strike
That is a perfect write up and is the idea I was thinking of. If the OP follows your post and adapts it to his vehicle and needs, he will have a great system.
 

Charles M

Rank V
Launch Member

Member III

2,771
Wickenburg, AZ, USA
First Name
Charles
Last Name
M
Member #

17640

Ham/GMRS Callsign
K1CJM
I agree with the other mixing two different types of batteries would be a problem... If they are both the same type and size you should be fine... I am running two standard identical batteries (bought at the same time also) on my Tahoe I can run a refrigerator for 48 hours with no starting problems.. For your use as long as you don't mix them it should work just fine.
 

Tim

Rank VI
Launch Member

Influencer II

4,750
Oxford, UK
First Name
Tim
Last Name
Lunn
Member #

0671

The only think I would add is when running batteries in parallel it’s recommended to connect the positive loads and charging input to one battery and the earths to the other.
IMG_7197.JPG
 

Sparksalot

Rank VI
Launch Member

Influencer III

4,312
Bastrop County, TX, USA
First Name
Rex
Last Name
Drake
Member #

19540

Ham/GMRS Callsign
KI5GH
Service Branch
Air Force
My Tahoe was factory equipped with dual batteries. They’re in parallel with no isolation, and are definitely matched.
 
  • Like
Reactions: Charles M