MEP-804B - New to me, I have a few questions

410Customs

Member
40
18
8
Location
North Idaho
Thanks fellas

Unfortunately for me it is one step forward and two steps back with this thing.
The new alternator is in! AND

Drum roll please..........................

NOT WORKING!
So yeah seriously now we have a new issue.
The new alternator installed is a 24V, 40 AMP unit
Installed just fine, wired up same as the old one, bolted right up, belt is tight

NATCAD I love this topic!! We are in the market for some new panels and a 3rd inverter...etc but that will have to wait until I can sort this charging issue out

As soon as I start the generator the ammeter pegs past +20 and in a few seconds the 25 amp circuit breaker pops and the unit quits charging
So I tried moving the ground wire, same thing
I get my multimeter out and check battery voltage
Before the circuit breaker blows the battery voltage was climbing....23.5, 24, 25....when it gets to 25.5 the circuit breaker pops and the alternator quits charging.

WHAT THE HECK IS GOING ON WITH THIS THING????????
The system should charge at 25-27 volts.
This is a new alternator tested before I installed it

So now I'm guessing we can see why the old Hitachi unit was failed, something is fishy

Lucky for me the battery charger I ordered on Amazon came and I was using that yesterday to recharge the batteries.
This is a Norco 2600 24V battery charger, I plug it in to the courtesy outlets and set it on 24V, hooked up to the battery bank...it was charging them just fine

So now I am thinking, well maybe I cannot use glass matt batteries in this unit? So I did some research
Nope........ the Optima red tops it came with were glass matt and they were approved for use in this unit
Are the batteries I installed too large? Drawing too many amps? I do not see how that is possible, they are just Everstart 12V group 65 AGM batteries
The gauge pegs way past +20 amps.........
IO have checked the battery wiring and alternator wiring 100 times, I know it is hooked up correctly

So do I have a bad circuit breaker (not likely)
what causes an ammeter to PEG? (too many amps right?)
Why would it be pulling too many amps enough to blow the CB every time?

New unit

Now I am starting to see why I got such a good deal on this thing



Any ideas on where to start?
New shunt? New circuit breaker? I am not a big fan on throwing parts at a machine, I would rather know what the heck to test!!


NOT GOOD!!!!!!

Our ducks:


our elk herd
 
Last edited:

loosegravel

Member
Steel Soldiers Supporter
54
54
18
Location
Enumclaw, Washington
Thanks fellas

NATCAD I love this topic!! We are in the market for some new panels and a 3rd inverter...etc but that will have to wait unfortunately until I can sort this charging issue out

Unfortunately for me it is one step forward and two steps back with this thing.
The new alternator is in! AND

Drum roll please..........................

NOT WORKING!
So yeah seriously now we have a new issue.
The new alternator installed is a 24V, 40 AMP unit
Installed just fine, wired up same as the old one, bolted right up, belt is tight

As soon as I start the generator the ammeter pegs past +20 and in a few seconds the 25 amp circuit breaker pops and the unit quits charging
So I tried moving the ground wire, same thing
I get my multimeter out and check battery voltage
Before the circuit breaker blows the battery voltage was climbing....23.5, 24, 25....when it gets to 25.5 the circuit breaker pops and the alternator quits charging.

WHAT THE HECK IS GOING ON WITH THIS THING????????
The system should charge at 25-27 volts.
This is a new alternator tested before I installed it

So now I'm guessing we can see why the old Hitachi unit was failed, something is fishy

Lucky for me the battery charger I ordered on Amazon came and I was using that yesterday to recharge the batteries.
This is a Norco 2600 24V battery charger, I plug it in to the courtesy outlets and set it on 24V, hooked up to the battery bank...it was charging them just fine

So now I am thinking, well maybe I cannot use glass matt batteries in this unit? So I did some research
Nope........ the Optima red tops it came with were glass matt and they were approved for use in this unit
Are the batteries I installed too large? Drawing too many amps? I do not see how that is possible, they are just Everstart 12V group 65 AGM batteries
The gauge pegs way past +20 amps.........
IO have checked the battery wiring and alternator wiring 100 times, I know it is hooked up correctly

So do I have a bad circuit breaker (not likely)
what causes an ammeter to PEG? (too many amps right?)
Why would it be pulling too many amps enough to blow the CB every time?

New unit

Now I am starting to see why I got such a good deal on this thing



Any ideas on where to start?
New shunt? New circuit breaker? I am not a big fan on throwing parts at a machine, I would rather know what the heck to test!!


NOT GOOD!!!!!!

Our ducks:


our elk herd
Depending on what batteries you’re using and the state of charge that they have you may be asking too much from your alternator. Try charging your batteries before starting the machine. It is a common misconception that alternators are battery chargers. They are not. When we try to charge batteries with alternators bad things can and do happen. They’re designed to replenish the power used to start the engine and to maintain a specific system voltage once the machine is running. If you are using over-sized batteries and the state of charge on them is low (like it sounds that it is) it is very possible that it is actually exceeding the 25 amp circuit breakers capacity. Start with fully charged, correctly sized batteries.
 

410Customs

Member
40
18
8
Location
North Idaho
VERY GOOD ADVICE

Thank you
I will charge them to 100% with my new charger and then try again
I am SURE that is it
I believe you are probably correct!!

batteries were at 22.5V when I installed the new alternator, well below 24V basically they were below 25% capacity and yes my dumbass expected the alternator to charge them up hahahaha

I feel good about this
I am looking forward to being able to move on and get back to the fun stuff like adding another inverter/charger on the 3rd leg
 

loosegravel

Member
Steel Soldiers Supporter
54
54
18
Location
Enumclaw, Washington
looking forward to hearing if that fixed the problem
I work as a mechanic for the transit company in Seattle. Been there for 25 years now. We often have buses with dead batteries in the yard, mainly from sitting so long waiting for parts. But that's a whole other problem! I always cringe when I see other techs who will routinely jump start these buses and then put them back in service without replacing the batteries, or properly charging them. We have (4) group 31 Odyssey AGM batteries in each bus. That is one heck of a lot of resistance on the charging system when these batteries are low on state of charge. The only "proper" way to treat these buses is to remove the low state of charge batteries and put them on the charging rack. Then install other, fully charged or new batteries. Instead what we get are trouble calls because the buses won't start after a lay-over. In other cases we get calls because "the bus smells like rotten eggs." This would be from the AGM batteries heating up and steaming out of the vents. And the worst case scenario is an unplanned thermal event, which we have had a few. I'll let you use your imagination on what this might look like. Good luck to you on your generator. I'm almost positive that you've got this problem licked!
 

Guyfang

Well-known member
8,988
3,316
113
Location
Burgkunstadt, Germany
New shunt? (Think about what a shunt is. It is more or less a fuseable link, and it is a way to reduce the amount of amperage in your Batter Charging System, AT the M4 METER. What you just do not want to do, and its cost me two wrenches and a big fat scream of F**K , when I managed to run afoul of the posts on the back of the Battery charging meter. So if you look at the MT4, (shunt) you will see, it works, or NOTHING works. Main power into the control cube is to the MT4. If its broke, meaning burnt through, nothing works. Thats the only failure MT4 can have.) New circuit breaker? (Did you look at the CB? See what its rated for? It might be doing its job, or someone may have put a smaller one in) I am not a big fan on throwing parts at a machine, I would rather know what the heck to test!!
 

410Customs

Member
40
18
8
Location
North Idaho
804b is purring like a kitten the batteries are at 75% I will shut off when they reach 100% and tomorrow we will reset the CB and try this again!
The charger says 7.8 hours to fully recover 24V AGM been running about 5 now.........
Big learning curve on these things :)
Thanks dudes
 

410Customs

Member
40
18
8
Location
North Idaho
all right well it took 3 days to get the generator run time needed to bring the batteries up to 100%
The generator charges our battery bank in just a few hours and the sun has been out (we have also had snow and rain!)
so not much generator time needed lately.
Last night when I shut the 804b down I saw that the two glass matts are finally at 100%!
So tonight we shall try to close the circuit breaker and see that the new alternator and charging system are indeed working
fingers crossed.

Been looking at batteries and solar panels............ please send $$$



 

410Customs

Member
40
18
8
Location
North Idaho
Allright you guys I finally had a chance to run the generator with the batteries fully charged
This time of year we have plenty of sunshine we hardly need to use this thing at all 7 months of the year

at first I was concerned because once again the ammeter pegged past 20+ amps and the circuit breaker blew
I let the 804b warm up and tried again
The ammeter went to 20+ but this time it began to drop... almost as if the system finally reset?
it seems to be a solid state setup with a shunt and ammeter, in any case, it looked like it was finally going to work.
Two hours later and indeed it is working! Finally a full hooked up a properly working gen set

Now I can focus on how to utilize that third leg!!
Thanks again all the advice and information is really appreciated
Very happy with this genset, I know we are only using 2/3 of its ability right now but even at 15/20% load it seems to just sip the red diesel, a huge upgrade vs the propane guzzler we had before
The 804b also had a little rattle can touch up, I have a selection of camo krylon paint and I wanted to remove all the bright tags the surplus machine had. I think it came out pretty well.
This summer we will be building a generator house
 

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NATCAD

Member
201
9
18
Location
Port Huron Michigan
looks good!
can anyone comment on what orifices might need plugged to prevent mice to get into generator box? does the 804a have holes on the bottom that need plugged like the 803a?
 
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