Battery Gr 31 AGM Unfamilar Territory

I am away from home base. Danged near to the point of turning my pockets inside out. The battery is for my BiPAP. Heart goes out of rhythm when power goes off in the middle of the night. I am also picking up an alarm pulse oximeter along with many other items. Cardiologist warned me I was on thin ice so the battery is not optional. It goes near the bed. A couple times a week the power goes off. It may be off for five hours then return for a couple of hours then go away for half a day, or a day. Hence the AGM and fast recharge. But the CheapOWatts need to be three or more to make the load safe. Not going to happen this trip. Delivery delayed. Can't even get the big pot. So it's back to basics. Dang near thinking about using 14 gauge to throttle output...

One wire that looks silver is tinned copper in speaker cable. Guaranteed.

Amazon can be great like that. I've gotten a few things for free, but had them send me return shipping labels on things I thought they would just say keep and refund me the money, but somehow they get extra special shipping rates and still profit by having the product returned

Anyway it appears you doubled up on the 8awg to the Shunt. It would be a neat experiment to put a clamp on DC ammeter over the individual copper and aluminum wires to see how much current each is passing when in parallel and the MW is maxed out.

I did a similar experiment on two 4 awg wires, one which had steel ring terminals. 85 % of the current chose the cable with brass terminals instead.

Amazon sided with me on it not being what I ordered from the vendor, and gave me a full refund and told me to keep the wire, too expensive for return shipping to the vendor in FL, and time intensive.

I ordered two ATC/ATO fuse holders that claimed to be 8awg, for a good price. When I cut the wire open and looked at the cross section, it was slightly narrower than known 10 awg and much narrower than my new Tinned Marine 8AWG. At least it is indeed copper

They came with 50 amp fuses though. The clear red insulation actually magnifies the appearance of the wire within. It looks like 6awg and impressive from the outside. the wire cutters revealed the illusion.

RJ showed me a link to buy 100 feet of 10 gauge copper red/black, and what they sent me was 10 gauge clear speaker wire, with what you noted, one side aluminum wire. No Bueno. But at least one side 10 gauge copper should handle 30 amps.

Niner, are you using speaker wire to pass current?

For shame........:)

Isn't one side aluminum wire.

Just kidding, I know you gave a short run to the battery and it doesn't matter at only 30 amps.

The voltage pot twiddling will be required when the battery is low enough.

I was always tweaking for maximum just below 36.2 amp buzzing threshhold amperage and this required 12 pot turns in the first hour with just one unit and one depleted battery.

Can't rightly speculate how often you would need to twiddle, or where you can set it so that twiddling is not needed.

I never stopped the test in the beginning to see what the voltage would have been at prebuzzing level at 50%, but it was in the lower end range of the trim pot, like below half.

So two of these cheapowatts, set at 13.2 initially, might very well buzz away for a period of time trying to feed that hungry lifeline.

Which of course was my reason for getting the 120$ Arabian MeanWell. Anti buzz, antismoke technology, and 40.92 amps with no voltage pot twiddling until I decide that ABSV has been held long enough.

Mex, as far as my Megawatt version...FWIW, if I drop the voltage from 14.8 to 14.4 at start up, the MW does drop the amps it provides to my T 1275. Maybe you want to install a volt meter on your chinesium, plug it in and start the voltage low, and then slowly adjust voltage upwards, to control the amp flows.


Don't exaggerate about needing a screw gun. If you start the volts low,the amps will be low also. Keep your ears in tune for the buzzing sound and don't make it buzz, and you should be good. Or water that money tree and buy meanwells next time.

Hi Mex,

What is going to be powered from the battery? How are you traveling?

Houston I have a problem. Damn! I have to come up with a charger or converter somewhere. The C.O.W.'s the pair do not stand a chance against this.

Mil gracias for the head's up. Wish I owned a money tree....

I see that the Lifeline GPL-31T Deep Cycle AGM Battery is rated at 105aH
Cold Cranking Amps
68 - 880
32 - 750
0 - 600

I have a Northstar AGM. it is rated at 90aH
77f -930cca.

I have seen this Northstar gobble up 75+ alternator amps when cycled to around 50%. The alternator belt was stretched and out of adjustment range and was squealing when over 1500rpm. My voltage regulator allows 14.9v, so it was maxed out. Have since installed new belt.

Since you are limited to 14.4, thats a half volt less potential. I would assume with the difference in CCA numbers between the two batteries and accounting for the capacity difference,

Well I think you might have to to some voltage pot twiddling for the first 10 to 15 minutes with 2 paralleled cheapowatts. I'd be interested if they start buzzing at 36.2 amps like mine did.

Perhaps give it a half hour of 13.2v, then dial them up to just below the buzz once more. I was shooting for 14.7 and pot twiddled upward for max amps just under the buzz until battery reached 14.7, then twiddling downward, and the cheapowatt terminal was well over 0.25 volts higher than battery, but my wiring was undersized for the task.