Inverter size

[Soundguy]

I'd get a pulled mounted tru to a sleave that fit the drive onthe mid pto, assuming you canuse the mid pto as well as other pto at the same time.. if you are using the rear pto.. etc.

Then belt over from the mid to the alt.. make up a simple box bracket and wire cage for the alt on the side of the tractor so only the belt and belt guard are under the tractor. make sure you ground the alternator as per it's polarity specs.. and the batteries as well.. then it will be a simple wire job.. might add in a large CB or fuse inthe charge line to match the rated / peak load of the alt, and also use wire rated for such load.. etc.

soundguy

I know this an older thread,but it sure is a good one and relevant to my current project.I've installed a 24V heater in my cab and it pulls 20amps on low and 25 amps on the high setting.Right now it's hooked in series to two deep cycle Group 27 batts rated at 182 reserve capacity minutes @25amps each.After reading here,it looks like a seperate charging system is going to be mandatory,even if I only use the heater for say 20-30 min at a time.

I've spotted a 1-wire 24V 50amp alt on ebay that I assume would work.I can use the mid pto under the tractor and it runs 2000 rpm.How do I make the transition from the pto shaft to the alt? Should the mount/pto shaft be electrically isolated from the tractor? And,how exactly should this be wired? Gauge required? Solenoid? Switch?

24V 50 AMP SELF XC 1 WIRE HOOKUP 10SI DELCO ALTERNATOR:eBay Motors (item 120427561567 end time Jan-24-10 09:47:20 PST)

 

[tshep]

In my experience - inverters cut out at what seems to be a fairly high voltage so starter solenoids will still work. Remember when you could jump around a Ford solenoid with pliers and get the starter to turn? Solenoids are much more voltage sensitive than motors - a very high 'pull' voltage is neccesary, and then a fairly small 'hold' current. Consumer-based inverters protect the starter solenoid voltage requirements from Ipods and such for car use. It would be nice if there was an override to a 'working voltage' for non-starter applications - but the default is for a specific reason.

 

[Soundguy]

many go into safety at 10.5v or so... which.. if you look at the discharge curve of a LA battery, you are already in deep doo-doo... at 11.9 static volts, a standard lead acid battery is considerd discharged. Mind you that is static load, and the inverter will be measuring the bat volts at operating load. Since inverters can source alot of current, that 10.5v at load likely climbs up a decent amount after being unloaded, especially if you let the battery set a couple of minutes. Likely enough for one good start attempt with not much more in reserve... I'm sure the alt loves that kind of a load. ie.. charging a dead bat...

soundguy

 

[SPYDERLK]

I agree. Those safety cutoffs Vs are set too high for high drain conditions. The idea for the safety cuttoff is to assure that you never run one of the cells in the 12 V batt completely dead while the others are still sourcing current. If this happens the strong cells will forcecurrent to continue flowing thru the dead cell and charge it backwards. This is very harmful. For that reason safety cutoff is always set at at least nominal bat V minus one cell. They have gone overboard in their protection except for low drain situations. A battery drained slowly, say 5 or 10 amps for a car batt, is pretty dead at 11.5 - which is about what they seem to be setting it at these days. Doesnt let you get a decent percent of discharge at hi drain tho. 10 or 10.5V cutoff would be gould in my opinion. That would let you pull 100A until the battery was about 50%.
larry

Alan, no lead acid battery is unharmed by deep discharge. Deep discharge batteries are just harmed less. It is not good to allow the terminal voltage of a 12V batt to drop below 10V under load. Such indication is either due to excessively high drain or a badly discharged condition. Starting a car in cold weather will often pull the battery to this level or even a little below due to high starter demand aggravated by the degraded performance of the battery at low T. However, the battery is immediately recharged and harm from the high drain is extremely slight. If immediate recharge is not done a deep discharge would have superior service life, however with prompt restoration of charge I find high cranking amp car batteries perform better and last longer with drains inherent in cranking and inverter use. It is frustrating for an inverter to cut out at so high a minimum. Given a circuit diagram I imagine a EE guru could figure out how to change the safety cutoff level. I would never want to go below the 10.5V range tho. A healthy battery under low drain is real near dead at that voltage. A charged healthy battery under high drain that drops its output to below 10.5 is at an extreme that will cause damage if sustained more than 10 or 20 seconds.

Dont run your deep discharge batteries all the way down unless the situation dictates. Theyll last longer if kept at a higher charge level. Just be sure to check the fluid level more often.
larry

In my experience - inverters cut out at what seems to be a fairly high voltage so starter solenoids will still work. Remember when you could jump around a Ford solenoid with pliers and get the starter to turn? Solenoids are much more voltage sensitive than motors - a very high 'pull' voltage is neccesary, and then a fairly small 'hold' current. Consumer-based inverters protect the starter solenoid voltage requirements from Ipods and such for car use. It would be nice if there was an override to a 'working voltage' for non-starter applications - but the default is for a specific reason.

I addressed this previously more completely in the quotes above than does the post below.
larry

many go into safety at 10.5v or so... which.. if you look at the discharge curve of a LA battery, you are already in deep doo-doo... at 11.9 static volts, a standard lead acid battery is considerd discharged. Mind you that is static load, and the inverter will be measuring the bat volts at operating load. Since inverters can source alot of current, that 10.5v at load likely climbs up a decent amount after being unloaded, especially if you let the battery set a couple of minutes. Likely enough for one good start attempt with not much more in reserve... I'm sure the alt loves that kind of a load. ie.. charging a dead bat...

soundguy

 

[/pine]

why the 24v alternators if it is independant of the tractor's system?

 

[Soundguy]

for the 24v heater perhaps?

soundguy

 

[/pine]

for the 24v heater perhaps?

soundguy

Yes, but I have seen others mention 24v alternators also...even in the OP of this thread it mentions a 24V alternator driven by the PTO...

I have seen it mentioned in other threads also....

I was just wondering what the advantage of charging one or more 12V batteries (in parallel) with a 24V (aircraft?) alternator was?

 

[SPYDERLK]

Yes, but I have seen others mention 24v alternators also...even in the OP of this thread it mentions a 24V alternator driven by the PTO...

I have seen it mentioned in other threads also....

I was just wondering what the advantage of charging one or more 12V batteries (in parallel) with a 24V (aircraft?) alternator was?

You would be charging them in series. The voltages add in series and that charge mode is much preferred with 2 like batteries because it guarantees they get equal current. This aids in maintaining their capacities equal. ... In a parallel connection both batts see equal voltage, and unless they are well matched one will end up taking a better charge. Also, in idle times in //, the battery that has a higher self discharge rate will draw current from the better battery compromising both batteries. In high reliability // circuitry, diodes are used to prevent the described discharge. You will not have to be concerned with this in a series connected string.
larry
ps. As for why a 24V alt - 2 possibilities. 1)There are 24V inverters. They would draw less current for the power out: P=IE ya know. These inverters are more expensive tho. 2)Clever use of diodes/switches to form a circuit where the batteries are charged in series by the 24V, but discharged in // by the 12V inverter.

 

[schmism]

my initial thought was 24v because you could go to a big truck bone yard and pick up a 24v alternator that is designed to put out 200+ amps easily. that and large inverters usually can run 24v and wire sizes are smaller on 24v, as well as the other advantages of having the 2 bats in series.