AGM battery upgrade

[abuck99]

Keep it Simple - H-7 AGM fits great, and has more than adequate starting /reserve power

$199 at Advance Auto ( and can usually find 25% off online) 3 year full replacement, locations just about everywhere...

View attachment 2333694

I've had this one in for a couple years, no issues, no special charger or alternator changes.... Also run two of them in my diesel, starts great winter and summer.

Good info- When you look at the performance numbers on the H7 vs X2, it gets kind of interesting:

Autocraft AGM H7: 80Ah, 140min reserve capacity, 850cca 1000CA weighs 52 lbs 3yr warranty price after 25% discount 149.95
X2 AGM 27F: 92Ah, 195 min reserve capacity, 930CCA, weighs 67lbs, 5yr warranty price after discount: $323.99

The X2 boasts some construction and technical performance benefits that the Autocraft ( or other AGMs) doesn't disclose: for example you can drain the X2 to 50% capacity over 900 cycles. Not sure if that can be done with the others.

Is this another case that you get what you pay for or are you simply paying an extra $174 for 12Ah of battery?

 

[Eyedaho]

Hi @Eyedaho
Product: MK3 Mini blade 7.5A (Electronic fuse version) | HKB Electronics
Mud Search (with mention of "hkb"): Search results for query: hkb

Thank you!!!

 

[hotdiggitydamn]

Thank you!!!

So I searched a bit but couldn’t come up with much. What is the consensus on this voltage booster vs a smaller pulley? I can see pros and cons to both.

 

[Eyedaho]

So I searched a bit but couldn’t come up with much. What is the consensus on this voltage booster vs a smaller pulley? I can see pros and cons to both.

I'm not an electrical engineer, but I think it depends on what you're trying to accomplish. I think when the engine is idling and the alternator is spinning slowly, it may not put out full voltage even if the electronics are essentially giving it full gas. In this case, the smaller pulley makes the alternator spin faster, and increases the voltage until the electronics limit it to 13V or whatever the level is. In the case of AGM batteries which require a slightly higher charging voltage, even if the engine is at a high RPM and the alternator is spinning like the dickens, the electronics are still limiting the output voltage to that same 13V or whatever level. In this case, the voltage booster causes the electronics to increase that voltage output, which supplies the correct voltage (14.2? 14.6? Idk) to charge the AGM batteries to their full potential.

 

[87warrior]

The ALT-S voltage booster mod can be made for a few bucks.
Detail thread: Alternator Voltage Booster

 

[suprarx7nut]

So I searched a bit but couldn’t come up with much. What is the consensus on this voltage booster vs a smaller pulley? I can see pros and cons to both.

I'm not an electrical engineer, but I think it depends on what you're trying to accomplish. I think when the engine is idling and the alternator is spinning slowly, it may not put out full voltage even if the electronics are essentially giving it full gas. In this case, the smaller pulley makes the alternator spin faster, and increases the voltage until the electronics limit it to 13V or whatever the level is. In the case of AGM batteries which require a slightly higher charging voltage, even if the engine is at a high RPM and the alternator is spinning like the dickens, the electronics are still limiting the output voltage to that same 13V or whatever level. In this case, the voltage booster causes the electronics to increase that voltage output, which supplies the correct voltage (14.2? 14.6? Idk) to charge the AGM batteries to their full potential.

I think you're close.

I'm also no EE, but my understanding is that the pulley might help increase the maximum current the alternator can put out. BUT, it would still be limited to the same voltage since the internals of the alternator and/or ECU should be managing voltage and keeping it steady (based on the sensing line). The sensing line modification "hides" a little voltage from the sensing line, making the alternator/ECU think it needs to bump up voltage a small amount to hit the target voltage. This can help you overcome the extra voltage needed to properly charge an AGM.

I don't think the pulley mod would be very helpful for a factory-ish power load. That might help if you were running a massive car stereo or power tools or something. For AGM concerns, you need the voltage increase (sensing line mod).

 

[hotdiggitydamn]

I think you're close.

I'm also no EE, but my understanding is that the pulley might help increase the maximum current the alternator can put out. BUT, it would still be limited to the same voltage since the internals of the alternator and/or ECU should be managing voltage and keeping it steady (based on the sensing line). The sensing line modification "hides" a little voltage from the sensing line, making the alternator/ECU think it needs to bump up voltage a small amount to hit the target voltage. This can help you overcome the extra voltage needed to properly charge an AGM.

I don't think the pulley mod would be very helpful for a factory-ish power load. That might help if you were running a massive car stereo or power tools or something. For AGM concerns, you need the voltage increase (sensing line mod).

That was a pretty through explanation of the differences. Thank you!

 

[menancyandsam]

Does anybody know the normal range of a sitting AGM battery. After sitting for over a week my voltage reads from 12.5 to 12.75, but I think from what I researched 12.75 means a 80-90% capacity & I just bought my AGM in Feb .

 

[Eyedaho]

I think you're close.

I'm also no EE, but my understanding is that the pulley might help increase the maximum current the alternator can put out. BUT, it would still be limited to the same voltage since the internals of the alternator and/or ECU should be managing voltage and keeping it steady (based on the sensing line). The sensing line modification "hides" a little voltage from the sensing line, making the alternator/ECU think it needs to bump up voltage a small amount to hit the target voltage. This can help you overcome the extra voltage needed to properly charge an AGM.

I don't think the pulley mod would be very helpful for a factory-ish power load. That might help if you were running a massive car stereo or power tools or something. For AGM concerns, you need the voltage increase (sensing line mod).

Oh yeah, good call. I was only thinking of the voltage differences given the question, and totally forgot about the increased amperage from the faster revolution on the pulley mod.