Further to my post about 2 alternators and their output, I'm looking at upgrading from a 60A alternator (stock on a 1990 22RE) to a 140A or 200A alternator. Those appear to be two of the options available that I can find. For those that have done an alternator upgrade, what fusing changes were made, if any? FWIW, the alternator manufacturer is saying to NOT put a fuse between the alternator and battery. If I'm reading my wiring diagram correctly, Toyota has several fuses in the alternator circuit, and a fusible link between the engine bay fuseblock and the battery positive. Goal here is to charge relatively new LIFEPO4 battery with a DC/DC charger (50 amp draw max), and power things like the winch from the starting battery, as LIFEPO4 and winching are apparently not a good mix.
Alternator Upgrade and fusing
- Thread starter jgranthevagrant
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Yeah you want a fusible link between alternator and battery. Also between battery and main vehicle feeds/fuse blocks. The starter motor is a direct feed from the battery (via a relay/contactor). Winch direct to battery, preferably with a high current marine switch - so only powered when you need it.
Most lifepo4 batteries in the 100AH range recommend 100A max draw. That's why you don't use them for vehicle starting, winching etc.
I run a victron dc:dc charger that charges my 100AH lifepo4 from the main battery/alternator path. It's a 50A unit, but I have it set to 30A (max). No point hitting the lifepo4 on the head with a hammer when 3-4 hours of driving will bring it back to full charge from full empty and with solar that's rare for it to ever be full empty.
cheers,
george.
Most lifepo4 batteries in the 100AH range recommend 100A max draw. That's why you don't use them for vehicle starting, winching etc.
I run a victron dc:dc charger that charges my 100AH lifepo4 from the main battery/alternator path. It's a 50A unit, but I have it set to 30A (max). No point hitting the lifepo4 on the head with a hammer when 3-4 hours of driving will bring it back to full charge from full empty and with solar that's rare for it to ever be full empty.
cheers,
george.
- Thread starter
- #3
That's pretty close to my thinking. Not sure why the alternator manufacturer would say "we do not recommend a fuse between alternator and battery", unless the higher output alts are prone to blowing fuses when going from low idle to high idle and higher amperage output? I think that the fusing between the battery and main vehicle feeds/blocks should be ok to stay the same, as those draws are not increasing. I put an OEM fusible link between my old AGM house battery and the new fuse blocks for accessory draws like the fridge, water pump, and so on. That is still in place on the new LIFEPO4 battery, and seems to be working well. I'm pretty sure my DC/DC charger can be set to a max draw also, but I will check on that. It is a Redarc. It will draw off the starting battery and the new alternator when the engine is running. Should draw off solar when parked and the sun is on the panel. I'm not sure how to construct or where to buy a fusible link or what rating it should be. If Alt puts out a max of 200 amps (I doubt it does in the real world), should the fusible link be rated at somewhere near that? I assume fusible link should be placed pretty close to where the alternator feeds the battery positive? Yes, my winch is run through large cables and a 500A Blue Sea marine switch. I'm thinking of doing something similar between the DC/DC charger and starting battery, so I can physically disconnect the two to protect the starting battery.
TreadingLight
"Overlanding is Sh*t"
When it comes to fusing and cabling, don't worry about what the alternator is theoretically rated to produce.
Think about what your actual power demands will be.
But the short answer is to add an 8g run of welding cable from alternator to battery, either through a midi fuse or a 12g 6" fusible link that you make yourself.
Think about what your actual power demands will be.
But the short answer is to add an 8g run of welding cable from alternator to battery, either through a midi fuse or a 12g 6" fusible link that you make yourself.
- Thread starter
- #5
Got the alternator in second week of august due to some shipping shenanigans. Starting on this project for real now. Phase one is the alternator wiring. Plan is to run from Batt post on alternator to fuse/ fusible link near start battery. Have not determined wire size yet, but at least 8, depending on length of run. Anybody who has done this before can chime in. Best to follow the original wire run from Alt to Batt? Anybody know the exact route on a 1990 22RE pickup? Looks like it comes off the Alt, down to the driver's side frame rail, up to DS fender, into harness, maybe back to firewall, along firewall behind engine?, then along passenger fender or wheel well to fuse box, through 80amp fuse, through fusible link, to start Batt positive? Looking at upgrading the grounds from start batt to frame as well.
- Thread starter
- #6
Took another look at it last night. Looked at diagrams in the wiring manual as well. Looks like the Alt to Batt+ wire runs across driver's side frame rail, up driver's fender, then across the rad support under a lip, I think under the battery tray, to fuse block (80 amp fuse), to fusible link, then to Batt+. I will most likely run alongside the stock wiring, as that looks like the shortest run.
You can keep the stock wiring as far as routing and just replace the original 80 amp fusible link with a higher rated one. They are exactly like the one you want to change out. Just rated higher.
When I swapped the 3.4 into my 88 (22RE) I just put in the 120 amp fusible link from the donor (99 4Runner) with 80 amp alternator. I just dropped the section of the fuse box with the fusible link, out the bottom to access the wires. It has two screws holding the wires to the posts. Swap in the higher rated fuse and pop it back in the fuse box.
This would be the time to hook up your heavier gauge wire since you have it disconnected.
Most auto parts stores or Amazon has the fusible links. You can even get OEM Toyota ones. Or generic like Little fuse or other brands.
Keep in mind that the fusible link may not be designed to blow open AT the rated amps. Many have a current/time curve they operate at. For example, one rated at 160 amps may carry 160 amps for a long period of time. Maybe 100%, but blow open at say 10% above that current after so many seconds. Blue Sea Systems show those charts for their fuses and such but I don't know how Toyota rates theirs.
Hope this helps.
Adding this pic I had in another thread the other day. My 88 under hood fuse box. You can see the fusible links. If you don't already know, (I didn't) the section of the plastic box with the fuses drops out the bottom. Push the tab you can see just in front of the 120 amp fuse.
When I swapped the 3.4 into my 88 (22RE) I just put in the 120 amp fusible link from the donor (99 4Runner) with 80 amp alternator. I just dropped the section of the fuse box with the fusible link, out the bottom to access the wires. It has two screws holding the wires to the posts. Swap in the higher rated fuse and pop it back in the fuse box.
This would be the time to hook up your heavier gauge wire since you have it disconnected.
Most auto parts stores or Amazon has the fusible links. You can even get OEM Toyota ones. Or generic like Little fuse or other brands.
Keep in mind that the fusible link may not be designed to blow open AT the rated amps. Many have a current/time curve they operate at. For example, one rated at 160 amps may carry 160 amps for a long period of time. Maybe 100%, but blow open at say 10% above that current after so many seconds. Blue Sea Systems show those charts for their fuses and such but I don't know how Toyota rates theirs.
Hope this helps.
Adding this pic I had in another thread the other day. My 88 under hood fuse box. You can see the fusible links. If you don't already know, (I didn't) the section of the plastic box with the fuses drops out the bottom. Push the tab you can see just in front of the 120 amp fuse.
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- Thread starter
- #8
Excellent info Aztoyman. I did not know there were other fuses available that will plug into the box. I have two boxes so I knew about the access from below. I might bypass the OEM wiring in the box and have an external fuse somewhere near the battery. Not sure where I'm putting that yet. Was pricing the fatter wire today and it is expensive. I use a lot of Blue Sea stuff for my camping electrical and my winch shut off switch.