97BlackAckCL
Elite Member
Yes, you'll see some variation based on load
"Voltage Booster" for 31M AGM Battery
- Thread starter ADVnut
- Start date
Thanks for the quick reply. what is that load based off? is the ecu measuring when the battery is 100% charged and lowering the voltage to just maintain the battery?
I was just curious as to whether I need to run it in overboost mode all the time to make up for that. When the voltage dropped there was not any significant load. I was cruising on the freeway at 80mph and it just stabilized at 13.8 which I believe is not sufficient for AGM's. I am running dual Odyssey 34's.
bring_it_on
New member
I think the voltage booster is merely boosting voltage by a set amount depending on the setting you've selected. So whatever voltage the smart alternator supplies will be boosted by that factor. I see fluctuations as well which you would have seen in the voltage even without the device installed. At the highest setting the max I've seen is 14.8 and it almost always stays above 14 volts. That and a solar panel takes care of my AGM though it doesn't hurt to put it on a tender with the correct AGM profile so that you do the multi-stage charge process every now and then.
Comparing a Traditional Alternator to a Smart Alternator | REDARC Electronics
97BlackAckCL
Elite Member
I was referring more to the load on the alternator, if for instance you're running in high temperatures like you noted 70-90 deg F your rad fans will be kicking on and off with the thermostat, etc. Which will change the voltage draw
Thanks. That does make sense, though on the 8 hr drive I just found it odd that it didnt go above 13.8 at all except for a couple minutes at initial startup.
i just want to make sure I keep the AGM properly charged.
Thanks for the info. do you leave it on overboost setting most of the time then? It seems like when the temps get hotter that is the only way to keep voltages in the correct range. It seems to be a fine balance of not under or over charging.
bring_it_on
New member
I switched it to overboost during the Chicago winter and haven't bothered bringing it back down. I think I'll just keep it at that (plenty of others do the same). I have never seen it go above 14.8 volts and/or at levels where I may start getting worried about it damaging something. I've also never really seen it dip significantly below 14 volts either. Though I have an Odyssey AGM, I don't deep cycle it (I have a separate house battery). The one time I did deep-cycle it, I made sure to hook it up to an AC charger overnight to bring it back up and I would continue to do that even with the voltage booster. Even though the voltage booster does give it adequate voltage, you are still not going to get the multi-stage charging that a DC-DC or a solar charge-controller (both configured with the right settings for AGM) will provide so best to use something like a NOCO if you deep-cycle often or if you use the Winch a lot or have loads of high power lights.
It is normal for the smart alternator to cut the voltage down when you are cruising on the highway. After the initial burst of voltage, post startup, they do tend to dial it back down (which is why we need the voltage boosters on these non constant-voltage alternators) so this is where your booster will come in since it is what gets your alternator to supply a higher voltage. Even if you set it at the middle setting, I think you should be fine as long as you don't deep cycle your AGM. If/when you do that, you could overboost it and that should help with correctly and rapidly charging your battery back up. I would still recommend periodically using an AC-DC charger or a solar to keep it topped up with the correct profile.
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Thanks! that does make sense. I do usually hit it with a NOCO Genius 10 after extended use. in this case I was camping on top of a mountain for 5 days so i just wanted to make sure the battery will recover properly on the occasions I did drive a bit in between. I will try the overboost setting and just need to make sure it does not go over 15v and damage the battery. It is getting to be summer here and temps are rising to 90 daily in colorado so I will just keep an eye on it.
Don't forget that the correct voltage depends on the temperature, so when it's really high you need a lower temperature.
You will need to check the stats for your own battery, but for example for my battery the correct voltage for charge/absorption/equalize is:
13.80 V to 14.60 V at 77 degrees F
the temperature compensation, for my battery, is:
18mV per every 1.8 degrees F (subtract for temps above 77, add for temps below)
if the battery temp is 100 F, then the correct charging voltage is:
(100F-77F)/1.8F * 18 mV = 230 mV, or 0.23V
since this is over 77 degrees I subtract, giving me a temperature compensated specified charging voltage for my battery of 13.57 F to 14.37 F.
again, check your own specifications, but there will be some kind of temperature compensation
You will need to check the stats for your own battery, but for example for my battery the correct voltage for charge/absorption/equalize is:
13.80 V to 14.60 V at 77 degrees F
the temperature compensation, for my battery, is:
18mV per every 1.8 degrees F (subtract for temps above 77, add for temps below)
if the battery temp is 100 F, then the correct charging voltage is:
(100F-77F)/1.8F * 18 mV = 230 mV, or 0.23V
since this is over 77 degrees I subtract, giving me a temperature compensated specified charging voltage for my battery of 13.57 F to 14.37 F.
again, check your own specifications, but there will be some kind of temperature compensation
VancouverRunner
New member
Just saw that the arclight voltage boosters will go up in price in 2022. Just a PSA if anyone wants to get one now.
Need help on the 1 Amp Diode Fuse to boost voltage
Any kind soul able to help where can I install this diode fuse if my toyota fuse box doesn't have ALT S 7.5A fuse? the only 7.5A are for AM2 in my toyota. Running on Din alternator socket 1 cable alternator. Looked high and low for answer but can't get any stuff to boost my charging above 13.8v
Any kind soul able to help where can I install this diode fuse if my toyota fuse box doesn't have ALT S 7.5A fuse? the only 7.5A are for AM2 in my toyota. Running on Din alternator socket 1 cable alternator. Looked high and low for answer but can't get any stuff to boost my charging above 13.8v
VancouverRunner
New member
What year is your 4runner? I thought all had the alt s fuse.
TheWraith
New member
Did you figure it out ???
Im trying to help a buddy with a 2020 4runner.
I encountered the same issue with a battery light coming on
TheWraith
New member
You do have one ... its on the middle row closer to the driver side fender part of your fuse box. In between the 10amp and 15amp fuse.
But the GM Diode fuse mod doesnt work because you have to deal with a battery light on the dash
TheWraith
New member
yup I saw that.
I was using the GM Diode Fuse mod. I wonder if the other fuse mod works ...
anyone found a go around???
For the Arclight VB, has anyone leave it in "overboos"? I've been testing mine in overboost mode. At initial start, my voltage will go 14.9-15.0V for a few minutes, but once it's running steady, it settles at 14.4-14.6V.
I have an odyssey 34r, and the optimum charge voltage stated is 14.4 - 14.8V. But my question is, for the first few minutes when I start my 4runner, and the voltage goes to 15V for a few minutes, would that damage my AGM in the long run?
I feel that leaving the arclight at just the "boost" mode, the voltage is not enough to charge the AGM. It will be in the 13.7-14.2V range.
Any feedback is greatly appreciated. Thanks in advance.
I have an odyssey 34r, and the optimum charge voltage stated is 14.4 - 14.8V. But my question is, for the first few minutes when I start my 4runner, and the voltage goes to 15V for a few minutes, would that damage my AGM in the long run?
I feel that leaving the arclight at just the "boost" mode, the voltage is not enough to charge the AGM. It will be in the 13.7-14.2V range.
Any feedback is greatly appreciated. Thanks in advance.
nope it's doesn't work on my car since totally there is no alt s slot at all. tried replacing all my 7.5A fuse but no reaction totally to charge high and remain same 13.5-13.8 still. any soul able to do Magic to newer model 1 cable toyota denso alternator to let it charge high?
rigtec
New member
Hi Chilow,
BY ALL MEANS; leave the VB in-line! It'll help compensate for the high resistance in the Jumper-cables, and the small clamp connector surface-area!
~rig~ Cheers!
rigtec
New member
Hi Gill925,
The "Tell-tale lamp" circuit works this way... In the D/S (fuse) Junction-box, there's a 7.5 Gauge fuse HOT in on or Start!. It's directed through a diode, and an LED (Instrument Cluster//Tell-tale lamp circuit)! It goes to the Alternator L terminal #4 (Pink wire).
If the L Term at the alternator is generating voltage, then there's "NO GND" for the battery lamp to work, so it stays off. If there's NO Power/Voltage at the alternator's L Term, then the HOT Gauge fuse finds a GND at the L Terminal, and so it... lights-up to let you know the alternator isn't charging!
I would check that 7.5A Gauge fuse FIRST, before condemning the alternator! Also the IG Terminal #2 on the alternator, a 7.5A IG1 (IGN fuse); also in the D/S fuse-box, supplies power to the alternator's rotor, so be sure to check that fuse; W/O that power source, "NO CHARGING!"
Please let us know how you made out... although I see this is an OLD thread; but someone may STILL be able to benefit from these talent guys here who are helping out phenomenally; which is just why this is the LARGEST 4Runner forum in the U.S.A!
~rig~ Cheers!
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