I was told once that 100-series have a difficult time charging the auxiliary battery because the "smart" alternator somehow doesn't charge it properly. Is there any truth to this?
Charging an Auxiliary Battery (1 Viewer)
- Thread starter Von Hayek
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hoser
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The UZJ100 alternator is not the smart type. It wants to charge standard SLA batteries. It can charge other types but is not optimally set-up for it. Some use AGM batteries and increase the charge voltage by installing a diode. Many report satisfactory results. If your 100 regularly sits on shore power, you can also have good results.
Using dissimilar batteries will never result in optimal charge for at least one of the batteries. Ideally, you have two different charging systems.
Using dissimilar batteries will never result in optimal charge for at least one of the batteries. Ideally, you have two different charging systems.
AZMoonshadow
SILVER Star
REDARC makes a product that will easily charge both batteries and take in solar. It's certainly doable.
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Nowadays the easiest and best way to do it is with a DC/DC charger. There's a ton of them on the market now. I run an AGM starter and Lithium Aux using a DC/DC and it works great.
With DC/DC the batteries are generally isolated when the motor isn't running and they also give you the ability to use different battery chemistry and sizes. Many DC/DC chargers also provide the option of connecting the batteries for self jump start purposes, plus solar charging of the starter battery and aux.
For best results with an auxiliary battery, you need an isolator to ensure the house battery is recharged first, then send power to the auxiliary battery.
www.redarcelectronics.com
For optimal charging for the auxiliary battery, you'll need a DC-DC (aka BC-DC) charger. AGM batteries need a charge rate around 14.4V, lithium is generally 14.8V. The UZJ alternator seems to be just under 14V charge rate, mid 14s with a diode.
www.redarcelectronics.com
I have a Redarc electronic isolator mounted next to the house battery, and you would have your DC-DC as close to the auxiliary battery.
Dual Battery Isolator - Smart Start SBI | REDARC
Designed to extend battery life & safely charge your auxiliary battery, you can go further with a dual battery isolator from REDARC. Buy online today!
www.redarcelectronics.com
For optimal charging for the auxiliary battery, you'll need a DC-DC (aka BC-DC) charger. AGM batteries need a charge rate around 14.4V, lithium is generally 14.8V. The UZJ alternator seems to be just under 14V charge rate, mid 14s with a diode.
DC to DC Chargers - 12V & 24V Charging Systems | REDARC
Our DC to DC chargers keep your battery charged whilst driving & will fully charge auxiliary batteries to a proven 100%. Buy online now.
www.redarcelectronics.com
I have a Redarc electronic isolator mounted next to the house battery, and you would have your DC-DC as close to the auxiliary battery.
Old school approach was a relay and/or switch - or just crudely connecting batteries I guess.
That's ancient history now.
Current method is a DC/DC charger. That's what you want. Some are cheap, some are expensive. All from a name brand are better than the old school methods.
I have a 100Ah lithium battery in the back which is charged through a Redarc Core DCDC charger.
It pumps out maximum 25A.
It pumps out maximum 25A.
Redarc has a 40amp and 50amp version too. All of them are solar ready as well.
Correct, these are rated for "outside" installation.
The Core is for inside only which suits me perfectly.
And yes, they have an inbuilt MPPT.
The Core is for inside only which suits me perfectly.
And yes, they have an inbuilt MPPT.
OP, yes, there is some truth to that notion, but not because our 100 alternator is very smart, it isn't IMO. At least not in the Euro sense like going down to 12.5V when not needed, etc. I also have not seen our OEM alternator (no mod) going to more than about 14.3V and a Lithium Iron Phosphate battery wants 14.6V to be fully charged, ideally (I would not go as high as the 14.8V stated above). So, yes, the basic alternator is not ideal for an auxiliary lithium battery, say, but it could be done, it's not like the truck will be thrown into orbit instantaneously. And, yes, a good DC-DC will give better control over what is going on, and is a good way to go, if a bit expensive.
OP: ket me know in case I’m highjacking your thread!
I have a similar idea. Got the slee dual battery tray, slee main battery upgrade and just decided to go ahead an order.
Will go with 2 Oddyssey: Group 31 and 35.
Then redarc 1240 (or 1250?).
Reading along the lines, but will just go for the “safe” option offering all possibilities.
I have a similar idea. Got the slee dual battery tray, slee main battery upgrade and just decided to go ahead an order.
Will go with 2 Oddyssey: Group 31 and 35.
Then redarc 1240 (or 1250?).
Reading along the lines, but will just go for the “safe” option offering all possibilities.
I really wish you could put a LiFePo4 or Li battery under the hood.
Great DIY guide
Great DIY guide
