What size alternator do I have in my RedHawk?

[Bill Johnson]

Originally Posted by Johnynorthland

I just looked at the instillation manual for my new 12V fridge, it states input voltage of 10.8V to 14V. So I’m assuming that 10.8 is the cutoff where my refrigerator compressor will shut down.

Having said the above, if I kept my LA battery or when/if I upgrade to an AGM, my voltage should never get that low, unless I seriously depleted my battery. 50% DOD should be around 12.2ish volts. So I should have nothing to worry about, and lithium isn’t necessary?

Yes, I am racking my brains out over this! My wife and I are tired of throwing out spoiled food! I promised her spending the money on the new 12V fridge will be the fix all. I don’t want to hear her if there’s an issue after spending all this money.

Might be worth testing your battery and see how it's holding up compared to new

[craigav]

Originally Posted by Johnynorthland

I’m also thinking this would be an easy swap out if I were to change it. Could I use the same cable’s?

I suspect so. I am not sure how much slack is on the cables with the current solenoid. However and in any case, if the LI-Bim can be installed where the existing solenoid is located, the cables should reach. I will take a look at mine tomorrow and see what it looks like on mine.

How many amps does your new fridge draw? (or watts). ~CA

[Johnynorthland]

Originally Posted by Bill Johnson

Might be worth testing your battery and see how it's holding up compared to new

I was just thinking the same thing. I wish I had a load tester for one. As a test, before we leave, I am also planing on fully charging it, then run only the refrigerator over night, and then check the SOC. But temps will most likely be very low end of November in NE PA, I don’t know how that will hinder the test.
My LA battery is almost 5years old, don’t know how much longer it’s going to last.

[Johnynorthland]

Originally Posted by craigav

I suspect so. I am not sure how much slack is on the cables with the current solenoid. However and in any case, if the LI-Bim can be installed where the existing solenoid is located, the cables should reach. I will take a look at mine tomorrow and see what it looks like on mine.

How many amps does your new fridge draw? (or watts). ~CA

Runs on 8amps but lower over night or when in low usage mode, but states it can draw up to 13.5 amps max

[Bill Johnson]

Originally Posted by Johnynorthland

Runs on 8amps but lower over night or when in low usage mode, but states it can draw up to 13.5 amps max

I was reading and a 12 volt fridge draws 30 to 55 ah a day, that might be too much for a 65ah battery since you should only use about 33ah, so the battery doesn't get depleted

[Johnynorthland]

Originally Posted by Bill Johnson

I was reading and a 12 volt fridge draws 30 to 55 ah a day, that might be too much for a 65ah battery since you should only use about 33ah, so the battery doesn't get depleted

I know! My battery is 66Ah so I only have 33Ah but that’s if I stick to a 50% DOD which is only a recommendation for a decent battery life, you can discharge further, my real concern is the voltage. I would only run off my battery for apx 15-20 hours max, (night before a trip), again if we happen to dry camp, which rarely happens, I have a solar Gen with 3.034wh of lithium to plug into. So at 10.8V minimum operating voltage on my fridge, hopefully it should be no problem? But more AH would be nice. Sams club has a deep cycle, Duracell, platinum, 100Ah, AGM for $214. This is a great price! Looks like I might just buy it, unless someone changes my mind.

[Bill Johnson]

Originally Posted by Johnynorthland

I know! My battery is 66Ah so I only have 33Ah but that’s if I stick to a 50% DOD which is only a recommendation for a decent battery life, you can discharge further, my real concern is the voltage. I would only run off my battery for apx 15-20 hours max, (night before a trip), again if we happen to dry camp, which rarely happens, I have a solar Gen with 3.034wh of lithium to plug into. So at 10.8V minimum operating voltage on my fridge, hopefully it should be no problem? But more AH would be nice. Sams club has a deep cycle, Duracell, platinum, 100Ah, AGM for $214. This is a great price! Looks like I might just buy it, unless someone changes my mind.

I have a Jackery 300ah battery pack but I haven't tried it on a load like that. I do know that if plugged into 120 volt the plugs are only good for 10 amps each and if 120 volts is converted to 12 volts you will lose a lot of capacity. If you can run the fridge on a12 volt connection on the power pack it will be much more efficient. My CPAP machine will use much more power if I plug it into one of the 120 volt plugs on the pack instead of the 12 volt outlet

[Johnynorthland]

Originally Posted by Bill Johnson

I have a Jackery 300ah battery pack but I haven't tried it on a load like that. I do know that if plugged into 120 volt the plugs are only good for 10 amps each and if 120 volts is converted to 12 volts you will lose a lot of capacity. If you can run the fridge on a12 volt connection on the power pack it will be much more efficient

Yea, I realize that. I’ve used mine for one night in the RV, we were conserving our electrical usage and it only used about 34% of its capacity, but I did not have the 12V fridge at that time. I did run my house fridge with it, overnight when we lost power last summer.


The only way I could go straight to the 12V/DC side of my unit would be to make up an adapter from the fridge, I’m not willing to go that far. I guess this is going to be a trial and error experience until I figure it out. But your right, it would be more efficient to go straight to DC, that’s why I would like to just use my house battery.

[Bill Johnson]

Originally Posted by Johnynorthland

Yea, I realize that. I’ve used mine for one night in the RV, we were conserving our electrical usage and it only used about 34% of its capacity, but I did not have the 12V fridge at that time. I did run my house fridge with it, overnight when we lost power last summer.


The only way I could go straight to the 12V/DC side of my unit would be to make up an adapter from the fridge, I’m not willing to go that far. I guess this is going to be a trial and error experience until I figure it out. But your right, it would be more efficient to go straight to DC, that’s why I would like to just use my house battery.

You will figure it out. Without searching someone on here purchased an agm that is125 Amp hours, that would help a lot

[Johnynorthland]

I have been searching for quite a while for both AGM and Lithium. I found this AGM that will fit with an odd 135Ah! VMAX XTR31-135 Trolling Motor Battery AGM Marine Deep Cy... https://a.co/d/4u5R9HY

But that 100Ah AGM Duracell at Sam’s seems to be a better deal, but do you or anyone else here, think an extra 35Ah (only half that is usable),is worth spending an extra $115?

[Johnynorthland]

Originally Posted by craigav

I suspect your alternator is 120 amp. However, it doesn't really matter as there isn't any need to change it out (even if it was more or less). You may want to add (for LiFeP04) a lifepo bim as Bill mentioned or imo even better a dc2dc charger.

I have a LifePo4 battery in mine, just a single ~130ah battery (although I have more I could add), and in fact I purchased a 40a Renogy DC2DC charger for it. However, due to various reasons I have never installed the additional batteries or the dc2dc charger and for several years now have never had any issues. From what I can tell, I likely do not get a 100% charge on the battery but that is actually good for the battery and all in all, it provides more hours of usage than the deep cycle 100ah battery it replaced. Point being, you could simply drop in a ~100ah LiFePo4 battery as I did and not have any issues. ~CA

Craig, what battery did you buy and how is it at cranking your gasoline generator?

[craigav]

Originally Posted by Johnynorthland

Craig, what battery did you buy and how is it at cranking your gasoline generator?

My experiences with LiFePo4 batteries are unique and not necessarily what I would consider as a comparison with BattleBorn or Renogy LiFePo4 batteries (or other popular brand names) which I have not owned or tested either.

Not too go deep, but I have purchased (several provided for free "evaluation") about 5 different unbranded batteries along with having purchased about ~15 others that were used medical supply batteries. (about 5 were new and some needed repair but I got them for a very low cost at less than ~$50 each). Most are Valence, PowerSonic, and a few others that I don't recall the brand. All are very similar in my testing.

With that, I only tried a few different ones in the RV as a "single" battery. These were the 100ah+ batteries and I have not encountered any issues starting the generator with any of them. From what I remember with my testing the Onan generator pulls about 50~60amps starting current but I never measured the initial surge current. I would expect the initial surge to be 3~4x that for a second or two most (or 150~200a). Also and important to note, my testing was in the summer with an easy to start generator. During very cold conditions and especially if the generator hasn't started in a while, the starting amperage could be a lot more.

Just for awareness, the BattleBorn 100ah batteries state that they can hold 2C (200 amps) for 30 seconds and even a lot more than that for an initial surge of current, which should start an Onan 4k just fine without any issues as again my measurement was that the starter only pulls around 50~maybe 60 amps after the initial surge. Without checking, I think Renogy rates theirs at 150a max current (which still should be fine for starting the Onan 4k but more of a concern than the BB 100ah battery which is rated higher).

My recommendation based on what Bill mentioned earlier that a 12v fridge uses about 30~55ah per day and along with your #13 comment that your concerns are more about intermittent stops during the day, I would purchase the Sam's 100ah AGM battery and keep life simple.

However, if your intentions were to power the RV and fridge for more than 24hrs without ever charging (generator, solar, or the chassis engine alt), then I would certainly consider the Battleborn 100ah battery, perhaps two of them. I would try to limit a 100ah AGM battery to ~75% discharge max, which should be enough for an overnight with the fridge running and if your furnace isn't running all night long (most of the night).

Not to go too deep or long, my suggestions overall and for others as well is when you need more battery capacity for extended usage between charge cycles then one or more LiFePo4's are the way to go. Once you get into the 300ah+ capacity requirements then the weight factor really comes into play with a Class C (and others), which at around 30# for each 100ah LifePo4 you can really save a lot of weight when compared to say 4~6x100ah lead acid batteries (assuming you wanted to stay at the 50~75% discharge max). Not too mention the other positive aspects such as the much faster charging ability and very long life you can get out of them.

So it gets back to an earlier comment I made asking about your battery capacity needs and from what I gather with your comments, I would choose the Sam's 100ah AGM. If your needs change one day, more boondocking for example (even then you have solar and an Onan gen you could use daily), then I would consider LiFePo4. ~CA

I will add, from reading a lot of comments here over the years, many RV'rs significantly under estimate their battery capacity needs. The needs add up quickly especially in the winter with the lights, furnace, fridge, tv, etc...

[craigav]

One other thought, if you stay with an AGM battery (or lead acid), you could consider an automatic generator start add-on made by Onan that would work fine for the Onan 4K generators and that component would start the generator as needed when\if the coach battery gets below a certain voltage. However, these are not recommended for use with LiFePo4 batteries. Another advantage with this is if you have a pet(s) and the shore power fails (no Air conditioning) especially on a hot summer day, it can auto start the generator based on a temperature setting so the RV never gets too hot due to a power failure. (assuming it doesn't fail, I am not sure I would like to risk my pet's life on this, but you would have to have two failures, first the shore power then this fail as well, so your odds are much better overall).

https://shop.cummins.com/CSSNAStore/...n-kit-a065u664

[Johnynorthland]

Thanks Craig, you’re absolutely right on every single point you make. I don’t need a lot of battery power, I know that, but my only concern is that low-voltage with the new fridge. And I don’t even know what I could possibly put on that would pull that much amperage to drop the voltage that low, besides starting the generator, and That will be charging the battery anyway!

Yes, that Sam’s AGM battery is looking better and better to me.


Thanks for the link for that auto start generator kit. That’s something I’ve always wanted to do, especially since we have a dog. I wonder how difficult it is to install? Now you got me on another quest!


Thanks again I’ll let you know what I do.

[craigav]

Originally Posted by Johnynorthland

Thanks Craig, you’re absolutely right on every single point you make. I don’t need a lot of battery power, I know that, but my only concern is that low-voltage with the new fridge. And I don’t even know what I could possibly put on that would pull that much amperage to drop the voltage that low, besides starting the generator, and That will be charging the battery anyway!

Yes, that Sam’s AGM battery is looking better and better to me.


Thanks for the link for that auto start generator kit. That’s something I’ve always wanted to do, especially since we have a dog. I wonder how difficult it is to install? Now you got me on another quest!


Thanks again I’ll let you know what I do.

It appears not to be an overly difficult installation process according to this link. https://www.absolutegenerators.com/m...S_brochure.pdf

I think I will consider purchasing one as well (primarily for starting the generator if the interior temp climbs too high). Absolute Generators website sells them for $467 which I have seen similarly priced in the years past.

Onan says they retail now for $344.99 but they are having a promotion for only $299 which is lower than I have seen in the past. Perhaps they don't sell so many and they desire to reduce their inventory... not sure of the reason but the price is better now than I have seen over the years. Onan is a reputable brand name for sure and this was made by them for their generators. BTW, the other reason I mentioned this is back to your other concerns with keeping the fridge running so you never spoil the food inside. ~CA

[Johnynorthland]

Originally Posted by craigav

It appears not to be an overly difficult installation process according to this link. https://www.absolutegenerators.com/m...S_brochure.pdf

I think I will consider purchasing one as well (primarily for starting the generator if the interior temp climbs too high). Absolute Generators website sells them for $467 which I have seen similarly priced in the years past.

Onan says they retail now for $344.99 but they are having a promotion for only $299 which is lower than I have seen in the past. Perhaps they don't sell so many and they desire to reduce their inventory... not sure of the reason but the price is better now than I have seen over the years. Onan is a reputable brand name for sure and this was made by them for their generators. BTW, the other reason I mentioned this is back to your other concerns with keeping the fridge running so you never spoil the food inside. ~CA

Lol I already did a YouTube search. Looks pretty easy. It connects to your both chassis and your house battery. I’m wondering if it draws power from both batteries for cranking in case the voltage is too low to start the generator?


Thanks again

[craigav]

Originally Posted by Johnynorthland

Lol I already did a YouTube search. Looks pretty easy. It connects to your both chassis and your house battery. I’m wondering if it draws power from both batteries for cranking in case the voltage is too low to start the generator?


Thanks again

It would only use the coach battery for starting, just as if you were manually starting the generator. Keep in mind, that it is monitoring the coach battery (perhaps chassis battery as well) so it should auto-start way before the battery is too low to start the generator, and from what I read, it is configurable in regards to what voltage level to start at. Perhaps someone here has installed one and has more details. ~CA

[Johnynorthland]

Originally Posted by craigav

It would only use the coach battery for starting, just as if you were manually starting the generator. Keep in mind, that it is monitoring the coach battery (perhaps chassis battery as well) so it should auto-start way before the battery is too low to start the generator, and from what I read, it is configurable in regards to what voltage level to start at. Perhaps someone here has installed one and has more details. ~CA

Looks like a good idea, my only concern is at my condo development, in Florida, I have free RV storage and it’s right near a bunch of houses and units. I would hate for this thing to start up in the middle of the night and upset anybody in the neighborhood. I don’t want to lose my storage for privileges either! I guess I would have to program it for quiet hours, but that would kind of defeat the purpose!

[craigav]

A lot of places I have camped at that do not have shore power do have quiet time restrictions and some even have a more restrictive generator run time schedule such as 2 hours morning and 2 hours evening. Something to consider for sure, however simply disabling the auto-start or setting the quiet time hours doesn't put you in a worse position than not having an auto-start. I would consider having one is simply another tool or aid to what I would do manually anyway.

I doubt anyone would complain (much) if the situation was that on a hot summer day there was a power outage and the generator started in order for the A/C to run in order to keep your dog from getting too hot. Also, if your battery can power the RV for ~24 hours, then auto-starting the generator at 8am due to a low battery should be fine as well as you should still have plenty of battery starting power left and then hopefully your solar kicks in later in the morning. You may be dipping closer to the 75% discharge by waiting depending on how much charge it had the night before, but on the other hand the battery should still have enough starting power.

Unless I go back to agm or lead-acid, the reason I would consider an auto-start would be more about keeping the inside cool in the event of a power failure and in particular if it was a hot day. If anyone complained about the generator noise during the power failure, I would likely apologize about the sound and explain it was necessary for my pet, if that didn't work then... I would... well I am a nice person so I would just ignore them after that.

[Johnynorthland]

I have found these specs while googling;

12.2 volts is a 50% discharge on a standard 12 volt battery. Gel batteries are a little different and have a voltage of around 12.85 when fully charged. When discharged to 50% the voltage should read around 12.35. AGM batteries will be around 12.8 to 13.2 volts when fully charged.
May 27, 2021

I’ve also read that there is going to be a Price increase across the board for batteries coming up shortly. And these batteries at Sam’s Club are going fast. My local Sam’s in Pennsylvania sold the two that I saw a few days ago! But I managed to find two other clubs not too far that had a bunch of them. So it looks like I’ll be making a trip back up to PA next week just to take care of this. According to the above voltage it should be no problem to discharge to 50% and maintain voltage need for my new fridge. Fingers crossed! What do you think guys?