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Dual battery setup for Avalanche 2500

CarMech1969

Full Member
Joined
Jul 1, 2016
Messages
498
Location
Scarborough, ON
Hello again, AVY fans!!  :cool:

Thinking about doing a dual battery setup for the 8.1 Vortec beast.
It runs and drives great, but it can be hard to crank when the temperature drops below -20.
Do you all figure that this would help solve the problem?
Truck already has a brand new 145 amp alternator and a newish 800 CCA battery.

Thanks all! Have a goodie  :B:

CarMech1969
 
I don't think adding a battery will make it easier to start just give you more reserve power if you have long sessions of cranking. I am no electrician or super cold weather expert but would have to guess that getting an engine block heater setup would be a better idea for -20 and below weather.....I think i have read somewhere about radiator fluid warmers and oil warmers too but don't know the effectiveness of those items. Of course it could also be a great excuse for a heated garage too.  >:D
 
block heater first
 
Welcome to the world of Chevrolet Big Block Motors, they are all hard to turnover when cold.

A engine block heater will help a lot if you have a outlet near.

You might want to check to see if you have the original starter if you do its over 16 years old..
If you decide  to change it maybe upgrade it to the gear reduction starter that came in the 03 up 2500

As far as a battery I stuffed a group 65 battery with  930 cca in mine and the second battery idea maybe a good idea as long as it's isolated

Pssss batteries plus has a 20% off sell going on car/truck batteries if you get the X2power brand you get a $30 rebate also, so that 302.00 battery comes down to 241.00 then 211.00 with the rebate.


Oh yeah I forgot this Warranty: 60 Month Free Replacement
 
-20, yes get a block heater would be best, but also the extra cranking power from a second battery can also help.

Factory battery tray PN-15246518 $25-$30 online Chevy parts or ebay.

Dual battery controller, with 250amp solenoid. Painless or Wrangler. I have the wrangle which I bought a long time ago before they raised the price.

Or you can buy the solenoid and battery cable and put your own together if your handy.

You just need.

1. Solenoid (250amp to 500amp)
2. Battery Cable (1/0 at least)
3. Copper ring connectors/battery clamps.
4. DPDT toggle switch. on/off/on
5. 16 ga. wire.
5. Shrink tubing.


This set up gives you control from inside.

Position one - Batteries are isolated isolated when the vehicle off and they tied togethe when running and both charge.
Position two - Batteries are isolated all the time, vehicle on or off.
Position three - Batteries are tied together all the time vehicle on or off. This position you can jump start yourself or give extra CCA when it's -20.


 
Thanks guys for the ideas!

MS03 2500: I have been through two starters on this truck since acquiring it. The starter that was on it developed a gnashing issue shortly after having remote start/Passlock issues. Threw a reman on there but it didn't last very long. I think it was just a weak starter. Bought a brand new one from RockAuto and it's been fine since - when I can get it to crank lol. This cold snap we've been having lately is not helping. Under normal conditions, the truck cranks perfectly fine.

Randy: I was thinking to use one of those battery terminal switch type thing that is usually intended to quickly disconnect the battery when parking the vehicle a while, to isolate the second battery. I had also thought of running a separate wire from the alternator to the second battery so that the charging current can reach the second battery more easily, and help prevent putting the load of 2 batteries on one wire. Then I would simply run the ground wire from the second battery to the engine block & chassis, and run the power wire from the second battery directly to the starter motor. That way, current has two separate cables to reach the starter, instead of all being shunted through one cable if you just did a positive to positive connection as is typical.

ygmn & Vaeagleav: What kind of block heater would be most effective? I thought of using the traditional core-plug type. Good idea?

Thanks again folks!

CarMech1969
 
I don't have a heater on my AV but doing an advanced search her I found about 10 pages of threads that may help you with info:

http://www.chevyavalanchefanclub.com/cafcna/index.php?action=search2
 
CarMech1969 said:
Thanks guys for the ideas!

MS03 2500: I have been through two starters on this truck since acquiring it. The starter that was on it developed a gnashing issue shortly after having remote start/Passlock issues. Threw a reman on there but it didn't last very long. I think it was just a weak starter. Bought a brand new one from RockAuto and it's been fine since - when I can get it to crank lol. This cold snap we've been having lately is not helping. Under normal conditions, the truck cranks perfectly fine.

Randy: I was thinking to use one of those battery terminal switch type thing that is usually intended to quickly disconnect the battery when parking the vehicle a while, to isolate the second battery. I had also thought of running a separate wire from the alternator to the second battery so that the charging current can reach the second battery more easily, and help prevent putting the load of 2 batteries on one wire. Then I would simply run the ground wire from the second battery to the engine block & chassis, and run the power wire from the second battery directly to the starter motor. That way, current has two separate cables to reach the starter, instead of all being shunted through one cable if you just did a positive to positive connection as is typical.

ygmn & Vaeagleav: What kind of block heater would be most effective? I thought of using the traditional core-plug type. Good idea?

Thanks again folks!

CarMech1969

For the Starter... I installed an AC Delco 337-1022 mini GM PN 88877121 I picked up at Summit $108.00. Spins the motor faster than the original.

Aux Battery - You don't want a manual switch that you have to mess with. And you can't just run a wire to the alternator without a battery isolator or it could draw from the battery and melt the wire.. The dual battery controller is the best way to go IMHO..

And for the block heater Kat's 11455 400 watt is the same as GM's... You can also add a battery warmer that helps cold cranking performance...

https://www.ebay.com/itm/Kats-Heaters-Custom-Engine-Block-Heater-11455-Plug-Style-120V-400W-28mm/332928787103?epid=1237836979&hash=item4d841a229f:g:MK4AAOSwsqxcCFzB:rk:2:pf:0

https://www.amazon.com/Kats-11455-Watt-Frost-Heater/dp/B000I8XCKE
 
When I did the dual battery setup in my truck I added a second alternator. I assume this is possible with the 2500 as well.

One thing to consider about with a second battery. It may actually make your starting worse.
With two batteries you have to consider the internal resistance. With two batteries you have more storage capacity but realistically the internal resistance is doubled while your voltage stays the same. That means you may not have the same discharge capacity when starting.

When I went to metra school they demonstrated how they could start a vehicle with 1 half charged battery. And showed with either battery. But with both batteries hooked up the car wouldn't start at all. All due to internal resistance of the batteries. This is the only place getting an OPtima red top or similar battery can help but then you are seriously taxing the alternator if the batteries get discharged too far.

Engine heater will help dramatically with cold weather starts.
 
Well it complained a bit and made some strange noises, but it started

Man is a big block hard to start when its cold outside.

0130191650.jpg
 
MS03 2500 said:
Well it complained a bit and made some strange noises, but it started

-4 Fahrenheit? Yup that's cold!!
Around here we use Celsius which would be around -20.
Anyhow, I have been putting a battery charger on the 2 amp setting overnight in order to keep the battery at maximum voltage.
This has helped temporarily relieve the issue.
Lately it hasn't been all that cold here so it's been ok for now.

MS03 2500 said:
Man is a big block hard to start when its cold outside.

Indeed it is!!

Thanks guys for all your input!

CarMech1969
 
-4 was at 5PM which was the high of the day at night it hit  -17
 
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