I'm replacing the cole hersee battery isolating solenoid because it's been working intermittently. The replacement is the exact part except the studs are about 1/8 shorter, and I can't fit all three of the lugs on the stud with room enough to screw the nut on top of them to hold them down.I'm thinking I need to buy a heavy duty bus bar in order to get these connected, but I don't know what size. Since the starter battery delivers 975 cca do I need a $130 1000 amp bus bar? Or am I going down the wrong track?

What I would do is just get a short #1AWG and bolt (really tight!)all four lugs together, then put the #1's other lug on the solenoid. Wrap the bolt and four lugs in tape for insulation.Of course everyone will be appalled and want you to spend the $130 :)

BFL13 wrote:What I would do is just get a short #1AWG and bolt (really tight!)all four lugs together, then put the #1's other lug on the solenoid. Wrap the bolt and four lugs in tape for insulation.Of course everyone will be appalled and want you to spend the $130 :)Not at all, Macgyver. That's simple and brilliant. :C

Another option is to get a short length of copper water pipe, flatten it in a vice, and drill suitably.The bus bar or whatever simply needs to be sufficient for the current flowing through it, not for the theoretical rating of the starting battery. At least in my RV that would be determined by the master fuses at either end of the solenoid, or something like 175A if I recall. Failing that, the wire sizes give some clues as to what to expect.

BFL13 wrote:What I would do is just get a short #1AWG and bolt (really tight!)all four lugs together, then put the #1's other lug on the solenoid. Wrap the bolt and four lugs in tape for insulation. Of course everyone will be appalled and want you to spend the $130 :)Great recommendation. I have done this and it works great but over time encountered a bit of corrosion where the wires are grouped together. Still a good solution.

Depending on the size of the lug.... There is a product you can get at a battery store that is a bolt/nut.. Basically it's a lug extenderIt may have long enough threads or you can put one lug under the extender and tighten it down then put the other 2 on it (or the other way around)

Not enough space for lugs on post of battery isolator

mapguy
Explorer
Jan 30, 2020
pauldub wrote:
This is probably a better solution Blue Sea Power Post

A GOOD CHOICE. Personally, not a fan of copper water pipe bus bars as they don't have easy peesey short out guards like the example.

These are available on the shelf at Fisheries Supply down on Northlake Ave in Seattle -very near Gas Works Park.
wolfe10
Explorer
Jan 30, 2020
Not sure nuts with half the threads would allow proper torque, and you sure don't want those high amp hots coming loose.
landyacht318
Explorer
Jan 30, 2020
Ace hardware carries 'jam nuts' which are nuts of half thickness.

I just used some on an alternator + output stud to free up more room for stacked terminals and homemade threaded copper nuts to avoid the steel nut from having to carry most of the current to ring terminal.

Make sure terminals can rest against each other flat before using the nut to compress them.
pauldub
Explorer
Jan 29, 2020
This is probably a better solution Blue Sea Power Post
RoyB
Explorer II
Jan 28, 2020
Check out BLUE SEA Products sold by AMAZON... My battery bank uses those HD Blue Seas four spade lugs terminals with covers... Got one painted BLACK for ground and RED for positive...

Google image...

I usually will only stack two connections to one terminal post...

Roy Ken
jjrbus
Explorer
Jan 28, 2020
I do not know about all RV's but my little Toyota sitting next to the house with a mostly OE system, the isolator is 100 amps continuous protected by 40 amp circuit breakers. So theoretically except for brief surges the most that can pass through there is 40 amps.

If I were in this situation I would likely flatten a piece of copper pipe and drill a couple holes. On the other hand an internet search will reveal all types of terminal extenders, expanders etc. Of course you will have to find the post size and thread size to match one up.
schlep1967
Nomad
Jan 28, 2020
Google Battery Post extender.$8-$10
Horsedoc
Explorer II
Jan 27, 2020
Belt sander and make the nuts a little thinner maybe? Or find thinner nuts at hardware store?
Lwiddis
Explorer II
Jan 27, 2020
I second BFL’s suggestion.
wa8yxm
Explorer III
Jan 27, 2020
Depending on the size of the lug.... There is a product you can get at a battery store that is a bolt/nut.. Basically it's a lug extender

It may have long enough threads or you can put one lug under the extender and tighten it down then put the other 2 on it (or the other way around)