Advice for latest car rewire

[PrivatelyJeff]

OK, installing in smaller vehicles is always a challenge. Just make sure you fuse appropriately.

Yeah, I’m actually probably going to go with fuses that are just big enough for the loads I going to use (because I don’t want to burn out the fuseable links on the studs). For me it just not wanting to climb back under the dash to upgrade later. I’m a big guy and it’s a small car. My next one will be one that’s more “flexible” when it comes to this stuff. I’ve learned with this car that Ford cut every corner possible to save a cent.

 

[RFI-EMI-GUY]

Actually, there is a way, just Google it.

Google "Porsche Terrible engineering".

Yeah well. One way is to find a tiny "special" terminal on the fuse block and snake massive jumper cables to it. Which is no help if you have no jumper cables , and are far away from home.

The $econd is to flatbed the car to Por$che $ervice Department where "Gunther" will put put the car on a hoist and remove the right front wheel, and the fender liner and fish out a $illy steel cable that manually overrides the latch.

I had to call for someone with a jumper cable and I did the Frankenstein treatment sparking to the fuse block with my fresh battery from the store.
Then after opening the silly frunk and installing the new battery I removed the right front headlamp and re-routed that $tupid manual cable into the bumper behind the tow hook cover, where it should have been in the first place. This in the highest heat and humidity of August in Naples FL. Not a fun way to spend time with relatives.

 

[PrivatelyJeff]

Ok, I’m working on this now. It’s getting to buying the battery stage.


I need some advice on picking a battery to my kit in my car when the engine is off (I’m installing a cut off system to disconnect from the car battery when the engine is off).

For the most part is just needs to keep a radio (15A max) and two scanners (3A) on and won’t be used much if at all if I’m transmitting (maybe just to quickly end a QSO).

Physical size is the key here. It needs to be small and able to fit under a small (2011 ford fiesta) front seat.

Would a basic 7ah SLA work? Can anyone make any recommendations?

 

[mmckenna]

Would a basic 7ah SLA work? Can anyone make any recommendations?

You need to consider charge voltage. The voltage put out by the alternator can get up in the 14 volt range. Some sealed lead acid batteries may not like being charge at that high a voltage. Take a close look at the specs for the battery and make sure it'll tolerate your alternator output.

Overcharging SLA's can make a mess. You'd be better off with a motorcycle wet battery, but mounting that under the seat isn't a great idea.

 

[PrivatelyJeff]

You need to consider charge voltage. The voltage put out by the alternator can get up in the 14 volt range. Some sealed lead acid batteries may not like being charge at that high a voltage. Take a close look at the specs for the battery and make sure it'll tolerate your alternator output.

Overcharging SLA's can make a mess. You'd be better off with a motorcycle wet battery, but mounting that under the seat isn't a great idea.

The device in charge of switching says it should be ok. I believe it isolates the battery once it’s charged.

ISOpwr+ - Auxiliary Battery Isolator - West Mountain Radio

Isolates and charges a 12 Volt auxiliary battery to run mobile radio and other 12 Volt portable equipment. Ideal for mobile radio command stations for ARES, RACES, FEMA, and for a VHF/UHF Contest Rovers, moderately powered ham equipment, a re-charging station for electric model airplanes, boats...

www.westmountainradio.com

 

[prcguy]

Why not install a delay relay for the radio equipment that shuts it all off at a programmable delay from zero to about 2hours. Set it for 20 minutes and you can operate your radios after you park then the relay will shut everything down after the 20 minutes. A second small battery is not a great solution. You can get them cheap surplus on Ebay like this one. Lidnd 12 volt DC shut down timer for Laptops, 2 way radios. Used | eBay

On the other problem of the battery going dead in a few days due to alarm, etc, junk that alarm and put in something else that uses less power. You should be able to park for at least a month wtihout running your battery down.

 

[PrivatelyJeff]

Why not install a delay relay for the radio equipment that shuts it all off at a programmable delay from zero to about 2hours. Set it for 20 minutes and you can operate your radios after you park then the relay will shut everything down after the 20 minutes. A second small battery is not a great solution. You can get them cheap surplus on Ebay like this one. Lidnd 12 volt DC shut down timer for Laptops, 2 way radios. Used | eBay

On the other problem of the battery going dead in a few days due to alarm, etc, junk that alarm and put in something else that uses less power. You should be able to park for at least a month wtihout running your battery down.

Because I want the equipment to also be able to stay on if I want it to, separate from car battery, for as long as I want it to. And I’m not tossing $500 worth of car alarm because that’s not going to actually solve that problem since modern cars have all kinds of computers that will draw power. We have two other cars that aren’t driven much and have a similar issue.

 

[mmckenna]

The device in charge of switching says it should be ok. I believe it isolates the battery once it’s charged.

ISOpwr+ - Auxiliary Battery Isolator - West Mountain Radio

Isolates and charges a 12 Volt auxiliary battery to run mobile radio and other 12 Volt portable equipment. Ideal for mobile radio command stations for ARES, RACES, FEMA, and for a VHF/UHF Contest Rovers, moderately powered ham equipment, a re-charging station for electric model airplanes, boats...

www.westmountainradio.com

That won't control voltage.

A gel-cell will like a charging voltage of around 14.2 volts, and like a float voltage around 13.2 or so. Your alternator will be putting out something likely above 13.8. Mixing battery chemistries like that usually isn't a great idea. But do what you'd like. It's not going to result in long battery life span, but a simple gel cell isn't going to break the bank.

I'd put the money into a better vehicle battery and use the Lind timer. Works well for a lot of public safety vehicle installs.

 

[PrivatelyJeff]

That won't control voltage.

A gel-cell will like a charging voltage of around 14.2 volts, and like a float voltage around 13.2 or so. Your alternator will be putting out something likely above 13.8. Mixing battery chemistries like that usually isn't a great idea. But do what you'd like. It's not going to result in long battery life span, but a simple gel cell isn't going to break the bank.

I'd put the money into a better vehicle battery and use the Lind timer. Works well for a lot of public safety vehicle installs.

so you’re saying it doesn’t do exactly what’s says it does

ISOpwr+ Features
• Properly charges a Lead-Acid (AGM or Gel) battery

And I have. It has the battery size that fits. I’ve replaced it several times (because stuff that’s directly connected gets left on, discharges the battery so low that it damages it and is unable to properly hold a higher charge for longer than a few hours). Even brand new, the equipment restarts when I start the engine. I need a system that keeps everything on when the engine is off, keeps it on when I restart the car, and also doesn’t drain the car battery if things get left on.

 

[mmckenna]

so you’re saying it doesn’t do exactly what’s says it does

Even they agree:

If using a GEL type battery, it also can be placed internally. However, confirm that the alternator voltage does not exceed 14.5 volts (at 70 degrees F). This will ensure full life for the GEL cell.​

Some of those old battery isolators didn't control voltage. It looks like this new one does, to a certain extent. That's a good thing.
This will work, but it's not ideal. Given your specific situation, it sounds like your best option.

My wife had a small Honda when we got married. While it didn't have any radios in it, it did have a small alternator and a small battery. The electrical issues with that car could be overwhelming sometimes. At idle, the headlights would dim if you turned up the A/C.
Small cars and radio installs are always a challenge.

 

[n0xvz]

I'm about to rewire my car (2011 Ford Fiesta)...

Sorry for the off-topic post, but you have my curiosity. I'd really like to see a pic of the install in that car. My daughter had an '11 (now has a '19), so I'm curious what is possible.

 

[PrivatelyJeff]

Sorry for the off-topic post, but you have my curiosity. I'd really like to see a pic of the install in that car. My daughter had an '11 (now has a '19), so I'm curious what is possible.

I’ll try. It’s possible but it’s VERY tight. All this the relay stuff is fitting in a small space under the shifter. The scanner and power stuff for that is under a seat. The battery part is looking to probably take up a footwell space in back.

Even they agree:

If using a GEL type battery, it also can be placed internally. However, confirm that the alternator voltage does not exceed 14.5 volts (at 70 degrees F). This will ensure full life for the GEL cell.​

Some of those old battery isolators didn't control voltage. It looks like this new one does, to a certain extent. That's a good thing.
This will work, but it's not ideal. Given your specific situation, it sounds like your best option.

My wife had a small Honda when we got married. While it didn't have any radios in it, it did have a small alternator and a small battery. The electrical issues with that car could be overwhelming sometimes. At idle, the headlights would dim if you turned up the A/C.
Small cars and radio installs are always a challenge.

It doesn’t (tops at maybe 14.1). I think that statement has more to do with overloading the isolator and it’s capabilities. I’m not asking too much of the battery, just keeping everything on when the engine is off/restarting. That aspect of the project started because when I go to run my errands and what not, I’m stopping and starting the engine and having to restart all the radios and equipment each time (sometimes a half dozen times in a half hour).

The isolation/cut off part is to avoid destroying another battery because things get left on and also the slow drain even the most minor of electronics pull on the tiny battery.