MEP-804A Battery charging issue maybe

[Landshark_3]

I have a MEP-804A I have been working on. I got all the bugs worked out but maybe one. This does not make any sense to me so hopefully someone has some insight.

This generator purrs like a kitten, runs great. It starts easy and has low hours, but on two different occasions it would not start. It seemed to turn over just fine but would not event try to start. This happened just after I replaced the VR and Governor control. So I started looking into it. I just to make sure I put a battery charger on it to make sure the batteries were fully charged. I came back after the charge and it started right up. It has done this on 2 different occasions. It will crank what appears to be at the normal speed but not start, charge the battery and it starts right up.

I did find the battery meter not showing a charge and found the belt loose and tightened it. This seems to have been the source of the real issue. My question is why if the battery will turn the machine over at what seems like a normal speed, but the battery may be a little low why will it not start? Is there something monitoring battery voltage or engine speed that prevents the fuel shutoff from opening? Like I said the issue seems to be fixed I just wonder what the real issue is.

 

[Guyfang]

All MEP-80X machines do not want to start when the Batteries are low. If you have weak batteries, then this will happen a lot.

 

[Landshark_3]

They are new batteries and the issues was the loose alternator belt. It just strikes me odd that something meant to be for military use can be so picky. I would think that if the batteries would turn it over at all it would try to start. I would hate to think I left the panel lights on a day or two and it wouldnt start because the batteries were just a tad low. But what you say confirms my suspicion. Thank you

 

[Guyfang]

All of the sets on start up, turn on the preheater. They draw a lot of amperage.

 

[2Pbfeet]

Just for perspective I don't know about the 804, but the intake preheaters (aka glow plugs) on '803 can draw 70-100A when cold on start up.

I believe that the Isuzu tip type glow plugs (01-360-3314) are closer to 25A total, but that's still a significant load on the batteries when the starter is trying to draw another 83-100A.

So, yes, fully charged batteries matter. There is a reason for that NATO plug.

All the best,

2Pbfeet