Hyster S40FT:
New Alternator Still Won’t Charge

Hi All,

I just put a new alternator, exact parts match, into our 2011 s40ft. forklift. This has a Mazda LP engine, and we verified that the battery is good.

When we tested everything, the battery tested fine, but the charging circuit is only feeding 3 A through the negative battery cable.

We don't know exactly where to start troubleshooting, and any tips were much appreciated. Is there some kind a fusible link, or is there a fuse that could be causing the issue? Again, thanks in advance for all your help.
  • Posted 9 Jan 2019 10:56
  • Discussion started by Hysterowner
  • North Carolina, United States
Showing items 1 - 4 of 4 results.
Thanks so much to everyone for your help. There seem to be a combination of factors that have added up to a no charge condition. First, the ground bolts were heavily corroded, second, the fuse was heavily corroded, third, the fan belt was somewhat loosely tensioned and the bolts holding the alternator (which we replaced) were not very tight.

We have one more ground to clean up, but a high-end SnapOn tester shoes that after hunting down all of the above issues, we did have a working charging system. Thank you all again.
  • Posted 16 Jan 2019 02:26
  • Reply by Hysterowner
  • North Carolina, United States
nominal output of the stock alternator should be 12v @ 50A
the output current should run around 13.5v and ammeter should read 10A or more at 1500 rpm, 35A or more at 2500rpm, or 49A or more at 5000rpm.
These units have an internal IC regulator.
Unloaded voltage: 14.7v +/- 0.3v

When checking your alternator output do not check it at negative, you check it at pos (B+) terminal.
Generally you want to make sure your voltage output is between 13.2v to 14.8v. (this may vary depending on how discharged the battery is).
There is a test to check the rectifier on the alternator but you will need the service manual to show you the table on how to test the rectifier array (best scenario is to remove alternator and take it to a repair shop for testing).

FYI: the ecm does not control the charging

Make sure ALL your connections are good, check the harness and make sure there are no faulty fuse links inline in the harness going to the alternator, and most of all make sure the battery is in good condition, load test it with a load tester.
  • Posted 15 Jan 2019 23:22
  • Reply by swoop223
  • North Carolina, United States
You've been swooped!
swoop223@gmail.com
Root issue may be failed alternator, wiring or regulator. Regulator may be embedded in an ECM, in that case I have bought aftermarket regulators and simply wired around the problem. AlternatorParts dot com , in Michigan, makes some good regulators and can answer any questions regarding specific application.
  • Posted 15 Jan 2019 02:58
  • Modified 15 Jan 2019 08:44 by poster
  • Reply by Jetty
  • Texas, United States
www.BacliffRV.com/Toyota_Forklift
Is the charge warning light on the display lighted? If not the charging system is working, you have a different problem. 3 amps out put is not low if the battery is charged and the load is low.
  • Posted 15 Jan 2019 00:32
  • Reply by BREWSKI
  • Nebraska, United States

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