Alternator upgrade

[MSN Member]

From: tshirtman
Sent: 4/14/2003

As I was playing today with my new toy, I noticed the alternator seemed pretty tiny. Not having any literature whatsoever I had to assume it is a 65amp. Can I just stick a 130 on, and is it necessary? See, I told you I don't know a thing about these RV's!
T-Shirts I know. Motors, RVs, how to get at spark plugs...nah...
                                                 John T

[denisondc]

Sent: 4/15/2003

I think the wire feeding the power from the alternator back to the battery would be larger on a vehicle that came with a 130 amp alt., and I have no idea about whether the Voltage Reg, but I am going to try and find out.   I am pretty sure it wouldn't hurt to put on a higher rated alternator, but unless you want to recharge your -house- batteries faster, and put in a larger wire from alternator to battery, I doubt you would ever see a difference.    What chassis and engine do you have?     denison

[MSN Member]

From: Boat Nut
Sent: 4/15/2003

As to upgrading of alternators:
Play it by ear. If you do a lot of boondocking & recharging of house batteries, (while you drive) appears to be a problem, go to a larger alternator. Also if you burn out the old alternator, that may be an indication that it was too small. If you were looking for a new alternator, be sure to look for one that is heavy duty. One that can handle the large load for a long time. Generally alternators are expected to only be required to handle their max load for a short duration, too recharge the starting battery.

Good luck

Chuck (73 Brave)

[MSN Member]

From: Dave1210
Sent: 4/15/2003

The napa part number for the stock alternator is a 7509-WP. The WP stands for wide pulley, if you get the 7509, which is readily available, the pulley will be for the smaller width belts so you will have to get new belts, but these belts will be too narrow in all the other pulleys in the engine and may wear quicker, but would work. You could have your pulley put on a new alt., mine was bent. This took me several tries to get the right alt. so I thought I would let you now before you attempt the project. They told me that this alt. was a heavy duty one but I do not know the amp output but it seems to work fine.

[MSN Member]

From: melyash
Sent: 4/15/2003

Having actually read the book Managing 12V systems, I can suggest that although a larger alternator may be an option, it is not that simple. Batteries have certain parameters they like to see, such as Gassing voltage and max amperage input ratings. You can actually boil your batteries by pushing them to hard. That being said, if you go to one of the after market High output Alternator MFR's they will be able to guide you with regards to what you may want to do. You will need to probably upgrade the gauge of wire from the new alternator as well. I strongly recommend the book, it is available from camping world or amazon. It really opened my eyes on what I could and could not get away with in that area. You can not just get a bigger alternator, and pour all that output into your battery, most of the high output alt's are designed for heavy loads such as winches, really big Stereo systems and other high drain items. The standard alternators may just have enough juice to meet the max acceptable input of your batteries. Also, the Voltage Regs on most vehicles do not have an optimum "voltage control curve" for effectively and efficiently charging Deep Cycle batteries.

If you have a generator, you may want to look at one of the intelligent chargers by Xantrex, like the 20plus or 20i. These units are designed to charge deep cycle batteries and are the best investment in keeping your batteries in good shape. You can charge close to the optimum rate, and do it on the small amount of gas the Genset takes, instead of the huge amount your V8 does. I learned a great deal from the book, and would strongly recommend it to be in everybody's bookshelf!

Matt Elyash

[MSN Member]

From: UluzYarx
Sent: 2/17/2004

Try adverc.co.uk, they explain why not ~ and recommend a second alternator.

[MSN Member]

From: HeavyHaulTrucker
Sent: 7/2/2004 10:37 PM

I have a tip that I learned when I upgraded the alternator in my old 1978 Ford E-150 van -- scrap the stock alternator wire.

Go to the auto parts store, and buy a suitable length of 4 gage battery cable, and two suitable crimp-on ring terminals.  The alternator feeds the starter relay -- with very few exceptions; simply measure your cable to run in the clips that hold the current loom that carries the alternator cable.  Cut to fit, attach your terminals, secure the wire in place and, WaLah! -- you now have an alternator that will supply the full rated amperage on demand.  If you want to do a "neat" job, you can unwrap the loom, remove the old wire, and re-tape the loom with the replacement in it before you install it back under the clips that secure it.

You see, the stock alternator wire is a punny little 10 or 12 gage wire -- the largest I have ever seen (which was on a Class 8 tractor) was 8 gage; it cannot supply the full rated output of the alternator if it is larger than 30 amps.  The solution is to replace it with a large enough cable to carry the current when needed.  You see, electricity flows on the surface of the wire only -- that is why stranded wire will carry more current than a solid wire of the same gage.  The larger cable offers more surface area for the current to flow, thus allowing more current to be conducted.

John

[MSN Member]

From: 73RVDUDE
Sent: 7/15/2004 9:05 PM

I upgraded my 73 440 to a 100 amp alt. it was fairly simple.