Big parasitic draw and already tested all circuits

[SUBURBAN5]

Dumb question.... what's a group 78 and how do I know what I got?

 

[thegawd]

The battery groups are like a standard. They are a sizing system LxWxH, it keeps manufacturers from both sides to conform to a system....

My 1994 yardman lawnmower, takes a power sports battery, not a lawnmower battery. I cant remember off the top of my head the sizes but I was pissed with cheap ****** lawnmower batteries that need replacing every year... and instead would jump it and not shut it off until the grass was done. BS. I began looking up the dimensions of the size I could fit in the allotted spot. Realized it is the same as most power sport batteries and so I found a deep cycle that fit the spot.... but before i had to learn all about the battery sizing system. Standard lawnmower batteries are much larger and easier to find good ones. I think it also dictates the posts but I could be wrong.

Take care.

Al

 

[PlayingWithTBI]

Yes a group 75 and group 78 are side terminals where a 34/78 have both top and side. You can scroll down and look up the differences in size.

https://www.oreillyauto.com/search/...pickup-rwd?q=battery+for+1988+chevrolet+C1500

 

[HotWheelsBurban]

Yes a group 75 and group 78 are side terminals where a 34/78 have both top and side. You can scroll down and look up the differences in size.

https://www.oreillyauto.com/search/...pickup-rwd?q=battery+for+1988+chevrolet+C1500

78 is the larger GM car battery, 75 is a smaller one, originally designed for compact and midsize cars. The 400 truck battery trays will hold a 78 series battery, and if installed properly the factory wedge plate style battery hold down works well. 34 is a shorter version of the old group 24 top post battery, that cars and trucks used before GM went to side terminals in 71 or 72.( used to have a 72 Monte Carlo and it had side terminal but my family's 70 Pontiac and 70 Monte Carlo had top post. ) 34 series is what later model Ford and Mopars use.

 

[SUBURBAN5]

Awesome. Thanks for the lesson. I did not know that lol. I've always just looked for the highest cca

 

[Matt98]

I know a lot of this has been stated, but test the battery first. If it’s good, get a cheap meter and hook it between the negative terminal and cable. It’s in your best interest to disconnect the negative terminal then run a jumper wire from that to the battery, wait a few seconds, hook your meter up and disconnect the jumper wire. This will eliminate the chance of the draw being high as everything is powering up and could potentially damage the meter. Leave it for 20 minutes or so, key out of ignition. Should be less than 0.05A. If it is more, pull every fuse one by one until it goes below that magic number

 

[Knuckle Dragger]

I know a lot of this has been stated, but test the battery first. If it’s good, get a cheap meter and hook it between the negative terminal and cable. It’s in your best interest to disconnect the negative terminal then run a jumper wire from that to the battery, wait a few seconds, hook your meter up and disconnect the jumper wire. This will eliminate the chance of the draw being high as everything is powering up and could potentially damage the meter. Leave it for 20 minutes or so, key out of ignition. Should be less than 0.05A. If it is more, pull every fuse one by one until it goes below that magic number

Solid advise advise on the jumper wire, I just don't think stuff this old has too much that go into "sleep mode" that he needs to worry about it. Pretty simple compared to the new stuff with a dozen modules waiting for the wake up signal.

 

[RawbDidIt]

Solid advise advise on the jumper wire, I just don't think stuff this old has too much that go into "sleep mode" that he needs to worry about it. Pretty simple compared to the new stuff with a dozen modules waiting for the wake up signal.

Depends, there's plenty of aftermarket loads that can draw enough to pop a fuse on a multimeter. We have no idea what's in this truck, so it's good advice in general, but definitely for newer vehicles as you mentioned.

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[Knuckle Dragger]

Depends, there's plenty of aftermarket loads that can draw enough to pop a fuse on a multimeter. We have no idea what's in this truck, so it's good advice in general, but definitely for newer vehicles as you mentioned.

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If the load is high enough to blow the meter the jumper will not help. You have to remove the jumper once the meter is hooked up.

 

[RawbDidIt]

If the load is high enough to blow the meter the jumper will not help. You have to remove the jumper once the meter is hooked up.

True, but some components have a high draw when first connected to power, particularly those with capacitors. Connecting the jumper initially allows the initial spike in current to pass before asking the meter to eat it. Not applicable to every situation, but enough to merit a mention. If the parasitic draw is enough to blow the fuse by itself it does nothing, as you mentioned, but taking away the opportunity for something else to go wrong does present a higher chance of correctly diagnosing the issue. And if the draw is enough to blow the fuse on a multimeter, I would hope the OP would mention the sparks that he saw when he reconnects the battery.

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