Choosing a Battery

laprof · Post by **laprof** » Sun Jun 02, 2019 1:26 pm

Hamguy515,
Thank you. I'll check out the 2nd battery you listed, although I'd still love to find one that's a wee bit lighter. Is it okay for use on a plane? Best.

laprof · Post by **laprof** » Sun Jun 02, 2019 1:33 pm

CapnLoki, Thank you for your reply! I like your suggestion for a Medistrom Pilot-24 since I can plug it directly into my Resmed. I will check it out asap. Best.

psteckler · Post by **psteckler** » Sun Jun 02, 2019 3:21 pm

Goofproof wrote: ↑
Sun Jun 02, 2019 11:17 am
The cable wiring should match what you are using it on.

Indeed, it should. I'm using a cable with a different source, so I want to know what input the cable expects.

Goofproof · Post by **Goofproof** » Sun Jun 02, 2019 3:26 pm

psteckler wrote: ↑
Sun Jun 02, 2019 3:21 pm

Goofproof wrote: ↑
Sun Jun 02, 2019 11:17 am
The cable wiring should match what you are using it on.
Indeed, it should. I'm using a cable with a different source, so I want to know what input the cable expects.

You need a voltmeter, and the specs for your machine, also some machines use three wires not two. Jim

You didn't give us a clue to what cable or it's specs, or your machine, not much to go on.....

psteckler · Post by **psteckler** » Sun Jun 02, 2019 4:47 pm

Goofproof wrote: ↑
Sun Jun 02, 2019 3:26 pm
You need a voltmeter, and the specs for your machine, also some machines use three wires not two. Jim

The device expects 24 VDC which, yes, I can measure with a multimeter. The only unresolved question is the polarity of the input to the 5.5x2.5mm plug. It's likely center-positive, which is much more common, but an expensive mistake if I get it wrong.

Muse-Inc · Post by **Muse-Inc** » Mon Jun 03, 2019 4:15 am

Don't forget this battery. Looks perfect for us 'clueless about electricity ones' as it comes with cables and separate plugs for the more popular xPAPs. Just a shame it's over airline limits. As my GoalZero continues to need more frequent recharging, I will likely buy this one. https://smile.amazon.com/dp/B074N8G8C7/ ... _lig_dp_it

Hamguy515 · Post by **Hamguy515** » Mon Jun 03, 2019 10:35 am

laprof wrote: ↑
Sun Jun 02, 2019 1:26 pm
Hamguy515,
Thank you. I'll check out the 2nd battery you listed, although I'd still love to find one that's a wee bit lighter. Is it okay for use on a plane? Best.

No, unfortunately the second battery (Bioenno LiFePO4) exceeds the FAA's maximum capacity restriction (must be <100Wh to carry aboard with few exceptions on a per-airline basis). That is another reason I selected the Medistrom, as it is allowed under current rules as it is rated at 98Wh capacity.

bbergin76 · Post by **bbergin76** » Sun Jun 09, 2019 5:44 pm

A lot of very useful information in this thread and I am trying to process it all. I'm actually not the one that has sleep apnea; my wife is the one with sleep apnea and I am doing research for her.

I am looking in to portable generators for tent camping purposes. We would only camp at sites we can drive up to and not backpack camping.

We were looking at something like this: https://www.rockpals.com/products/250-w ... Aqnf8P8HAQ

I'm trying to understand the calculations, how many days would something like this last, using a Dreamstation without humidifier and a pressure setting of 12? I know I'll need to get a DC adapter for the Dreamstation to run it at 12V to save power so I am looking in to that as well.

Ultimately we'd love to have something that would last 4 to 5 days without charging but that seems like a tall order. with a generator instead of a battery, but a portable generator would have a higher WAF than a battery setup like detailed in this thread. We would have our Town and Country with us which we could use to recharge the generator if necessary as it has "cigarette" outlets, one works with the key on and the other just works from the van battery, but what risks do we run in to charging through the van? Will we drain the van? Is it possible to recharge without having the van motor running? What are the downsides to that, if it is even possible?

Sorry about all the questions, just trying to wrap my head around all of this. I hope this rambling makes some sense.

Thanks in advance!

CapnLoki · Post by **CapnLoki** » Sun Jun 09, 2019 8:10 pm

bbergin76 wrote: ↑
Sun Jun 09, 2019 5:44 pm
A lot of very useful information in this thread and I am trying to process it all. I'm actually not the one that has sleep apnea; my wife is the one with sleep apnea and I am doing research for her.

I am looking in to portable generators for tent camping purposes. We would only camp at sites we can drive up to and not backpack camping.

We were looking at something like this: https://www.rockpals.com/products/250-w ... Aqnf8P8HAQ

I'm trying to understand the calculations, how many days would something like this last, using a Dreamstation without humidifier and a pressure setting of 12? I know I'll need to get a DC adapter for the Dreamstation to run it at 12V to save power so I am looking in to that as well.

Ultimately we'd love to have something that would last 4 to 5 days without charging but that seems like a tall order. with a generator instead of a battery, but a portable generator would have a higher WAF than a battery setup like detailed in this thread. We would have our Town and Country with us which we could use to recharge the generator if necessary as it has "cigarette" outlets, one works with the key on and the other just works from the van battery, but what risks do we run in to charging through the van? Will we drain the van? Is it possible to recharge without having the van motor running? What are the downsides to that, if it is even possible?

Sorry about all the questions, just trying to wrap my head around all of this. I hope this rambling makes some sense.

Thanks in advance!

First, the "calculations": your wife's Dreamstation will draw about 5 amp-hours a night, so 5 nights would be 25 amp-hours. Your selected "generator" is only 20 amp-hours so this is a real stretch. On the other hand, the U1 AGM battery I recommend is 35 amp-hours so it should cover the load with a reasonable margin to spare. And with the money you'd save you can get two AGMs or a larger one.

The product you selected is a "generator" only in the mind of a marketing department. It is simply a battery with a small charger and inverter. The added value is the light weight of the lithium cells, but if you're parking next to the tent this is of little value - you could even leave the battery in the trunk and run a 12V extension cord, And at a cost of $215 for a battery not quite large enough, compared to about $100 for a setup with overkill, ... i think you can tell how I feel about this.

As for charging from the van, if the engine is running there is no risk of draining the battery, but I'm not sure how long it would take. I didn't see any mention of how fast it will take a charge from 12V, only that it takes 8 hours to fully charge from 120V AC. Without the engine running it is possible to drain the starting battery to the point of not being able to start. You'd do better just running the pump directly from the car, not that I'd recommend that!

And what's a WAF?

bbergin76 · Post by **bbergin76** » Sun Jun 09, 2019 8:32 pm

CapnLoki wrote: ↑
Sun Jun 09, 2019 8:10 pm

First, the "calculations": your wife's Dreamstation will draw about 5 amp-hours a night, so 5 nights would be 25 amp-hours. Your selected "generator" is only 20 amp-hours so this is a real stretch. On the other hand, the U1 AGM battery I recommend is 35 amp-hours so it should cover the load with a reasonable margin to spare. And with the money you'd save you can get two AGMs or a larger one.

The product you selected is a "generator" only in the mind of a marketing department. It is simply a battery with a small charger and inverter. The added value is the light weight of the lithium cells, but if you're parking next to the tent this is of little value - you could even leave the battery in the trunk and run a 12V extension cord, And at a cost of $215 for a battery not quite large enough, compared to about $100 for a setup with overkill, ... i think you can tell how I feel about this.

As for charging from the van, if the engine is running there is no risk of draining the battery, but I'm not sure how long it would take. I didn't see any mention of how fast it will take a charge from 12V, only that it takes 8 hours to fully charge from 120V AC. Without the engine running it is possible to drain the starting battery to the point of not being able to start. You'd do better just running the pump directly from the car, not that I'd recommend that!

And what's a WAF?

Thank you for the response. I kind of figured the generator I was looking at wouldn't last the whole time and would need a recharge but wasn't positive.

I do have an A/C outlet in the van that has 115 power but I've yet to try to use it.

WAF in the sense of Wife Acceptance Factor. If it looks difficult to use she probably won't like it. Lol.

So let's say I go with a setup like what you recommend with 35AH and use 20-30 of it without charging, is there any damage being done to the battery? I want something that'll last for a long time, but I'm not sure the wife would go for running the van on idle for awhile to recharge.

Thanks again for helping out, I feel a bit clueless with this!

Goofproof · Post by **Goofproof** » Sun Jun 09, 2019 9:34 pm

Using a car alt is a poor solution for charging a battery, the charging voltage is too low to provide a fast charge, and the time needed would be too long, unless you were driving the vehicle anyway. By using the 110 volt inverter, and a battery charger of the needed specs While Normal Driving would charge faster, but would incur losses also. Jim

CapnLoki · Post by **CapnLoki** » Mon Jun 10, 2019 4:02 am

bbergin76 wrote: ↑
Sun Jun 09, 2019 8:32 pm
Thank you for the response. I kind of figured the generator I was looking at wouldn't last the whole time and would need a recharge but wasn't positive.

I do have an A/C outlet in the van that has 115 power but I've yet to try to use it.

WAF in the sense of Wife Acceptance Factor. If it looks difficult to use she probably won't like it. Lol.

So let's say I go with a setup like what you recommend with 35AH and use 20-30 of it without charging, is there any damage being done to the battery? I want something that'll last for a long time, but I'm not sure the wife would go for running the van on idle for awhile to recharge.

Thanks again for helping out, I feel a bit clueless with this!

All batteries wear out as they are used, and generally wear more when deeply discharged. The question is what is the appropriate level? For those trying to maximize the number of cycles 50% it the rule - this allows for hundreds, even several thousand cycles. I get 7 years from a set of batteries on my boat, and that's about 700-1000 cycles. However, for the occasional camper the battery will likely die of old age before you get to 100 cycles so you can push it further - at 80% you should get 200 to 400 cycles. Lithium packs are often rated for 500 deep discharges.

They "cycle life versus depth of discharge" is one of the primary specs of a battery, and you can easily find charts that show this. AGMs and and other lead acid batteries are mature technology so you don't see much variation, other than the differences between deep cycle and stating batteries. Lithium cells are still evolving so there are huge variations in the cell parameters. BTW, the real magic in a Tesla is the battery life - guaranteed for 8-10 years of daily service with only 30% loss of charge.

As for using the AC outlet in the car, remember its probably only 50% efficient to charge another battery with that, so charging a 20ah battery will cost 40ah, and that's easily enough to deplete a starting battery. (And starting batteries cycle life is very poor with deep discharge!) Much more cost effective to just start with an oversize battery.

bbergin76 · Post by **bbergin76** » Mon Jun 10, 2019 6:47 pm

CapnLoki wrote: ↑
Mon Jun 10, 2019 4:02 am
All batteries wear out as they are used, and generally wear more when deeply discharged. The question is what is the appropriate level? For those trying to maximize the number of cycles 50% it the rule - this allows for hundreds, even several thousand cycles. I get 7 years from a set of batteries on my boat, and that's about 700-1000 cycles. However, for the occasional camper the battery will likely die of old age before you get to 100 cycles so you can push it further - at 80% you should get 200 to 400 cycles. Lithium packs are often rated for 500 deep discharges.

They "cycle life versus depth of discharge" is one of the primary specs of a battery, and you can easily find charts that show this. AGMs and and other lead acid batteries are mature technology so you don't see much variation, other than the differences between deep cycle and stating batteries. Lithium cells are still evolving so there are huge variations in the cell parameters. BTW, the real magic in a Tesla is the battery life - guaranteed for 8-10 years of daily service with only 30% loss of charge.

As for using the AC outlet in the car, remember its probably only 50% efficient to charge another battery with that, so charging a 20ah battery will cost 40ah, and that's easily enough to deplete a starting battery. (And starting batteries cycle life is very poor with deep discharge!) Much more cost effective to just start with an oversize battery.

Thank you for all the help CapnLoki. Based on all of this it seems like my most economical option for 4 to 5 days would be the 35AH battery with a recharge once we are back home. I think we would only need it for the wife's Dreamstation as we have smaller power banks that we could use to charge cell phones if it came to that. Generally we don't have cell service but we do load music on our phones and use a bluetooth speaker to listen to music while camping.

Looking at an earlier post it looks like I"ll need:
Battery: https://www.amazon.com/dp/B00IIZ0IS8 - $69 right now.
Box: https://www.amazon.com/gp/product/B006RKCO3I - $16
Charger: https://www.amazon.com/gp/product/B00068XCQU - $45 - I assume the medium one is all I would need for purpose? Would I want to consider the larger one?
Quick Disconnect: https://www.amazon.com/gp/product/B0041CDPQO - $10
12V DC Adapter: https://www.thecpapshop.com/shielded-dc ... s-machines - $25

Total So Far: $165

How would I go about adding cellphone chargers using https://www.amazon.com/gp/product/B003L643KS? Would I need additional Quick Disconnects coupled with a USB cigarette adapter? Or something else? Not sure I would opt for this as we have other power banks for them but it might actually be useful for charging the bluetooth speaker, unless that will draw too much out of the battery? Having the battery last 4 to 5 days of CPAP use is more important than having a charged speaker.

If I'm reading your power usage numbers correctly, looks like our usage would double if my wife uses her heated hose, so I'm guessing we need to get an unheated hose to make this work.

Couple other questions I have if you don't mind:
This one may be really dumb but how does the Quick Disconnect actually connect to the Battery (and box)?
What is the best way to keep track of how many AH have been used and how many are remaining on the battery?

Thanks again for all the help. I think I am starting to catch on here!

Lane101 · Post by **Lane101** » Tue Jun 11, 2019 4:52 pm

Good advice from CapnLoki on purchase of a U1 battery. At a max 80% discharge it gives you 28 amp hours of usable power without a recharge. Per CapnLoki's estimate of 5 amp hours per night you should be covered for 5 evenings. This is also consistent with my experience (see earlier post in this thread) on different machines.

Regarding what you spec'd out:

Battery:

Amazon ratings of the Universal battery look dodgy and sparse. At 35 ah the Mighty Max Link below has better ratings:

https://www.amazon.com/Mighty-Max-Batte ... HW9PA9EDQC

I've had good luck with ExpertPower 20ah batteries. They also offer a 33ah version with reasonable ratings.

Quick Disconnect:

The quick disconnect you listed has an SAE style connector. You will want an O-Ring style of connector that is fused and can be bolted on to the battery. I've had good results with the NOCO GC018 (Link Below) that includes a replaceable auto fuse (also essential for safety).

https://www.amazon.com/NOCO-GC018-Adapt ... ive&sr=1-1

Note that you will need to replace the 15 amp fuse with one of a lower ampacity to protect your equipment. I use 5 amp fuses on my CPAP machine connections. This should cover you so long as you don't use your CPAP humidifier. Also, while you could connect to the SAE quick-disconnect O-Ring connector that comes with the Deltran chargers (see below) our Deltran is fused at a higher level (7.5 amps) than the 5 amps that may be ideal for your CPAP. Easier to just hook up two separate connectors to the battery so you can fuse appropriately.

We use a standard auto cigarette lighter 5 volt USB charger in our NOCO adapter socket. Since you are so close to battery capacity for your wife's CPAP usage over 5 nights you may not be able to support this with one battery unless you move to one with higher capacity (e.g. 55 amp hour @ 38 lbs. or buy a second battery as CapnLoki mentioned). Note that some camp sites may provide a charging station for batteries used for medical devices - if so you will be fine.

Charger:

Regarding the charger, the Deltran is a good model though with a 35 amp hour battery you can charge it at a faster rate. The 1.25 amp charger will take almost a day to fully recharge from an 80% discharge level. I've had good results with the Deltran 3 amp Battery Tender Plus charger at Costco that is only $39 and will charge more than twice as fast. If you are not a Costco member Deltran has a 5 amp version that will be within the specs of a 35 amp hour battery. Note that the Costco version comes with a fused SAE connector with O-rings that connect directly to the battery. The charger plugs directly into this. The charger you selected also includes one.

Costco Link: ttps://www.costco.com/Battery-Tender-Power-Plu ... 41973.html

Don't forget electrical tape to cover any bare terminals/connections inside the box for added safety. Feel free to reach out with additional questions. You may also need some nuts and bolts with locknut washers to connect your O-Ring connectors to the battery. Hope this helps.

Note that during the off-season you will need to charge the battery every three months and after 6 months of storage cycle it 20-30% and then recharge to avoid sulfation.

bbergin76 · Post by **bbergin76** » Tue Jun 11, 2019 7:58 pm

Lane101 wrote: ↑
Tue Jun 11, 2019 4:52 pm
Good advice from CapnLoki on purchase of a U1 battery. At a max 80% discharge it gives you 28 amp hours of usable power without a recharge. Per CapnLoki's estimate of 5 amp hours per night you should be covered for 5 evenings. This is also consistent with my experience (see earlier post in this thread) on different machines.

Regarding what you spec'd out:

Battery:

Amazon ratings of the Universal battery look dodgy and sparse. At 35 ah the Mighty Max Link below has better ratings:

https://www.amazon.com/Mighty-Max-Batte ... HW9PA9EDQC

I've had good luck with ExpertPower 20ah batteries. They also offer a 33ah version with reasonable ratings.

Quick Disconnect:

The quick disconnect you listed has an SAE style connector. You will want an O-Ring style of connector that is fused and can be bolted on to the battery. I've had good results with the NOCO GC018 (Link Below) that includes a replaceable auto fuse (also essential for safety).

https://www.amazon.com/NOCO-GC018-Adapt ... ive&sr=1-1

Note that you will need to replace the 15 amp fuse with one of a lower ampacity to protect your equipment. I use 5 amp fuses on my CPAP machine connections. This should cover you so long as you don't use your CPAP humidifier. Also, while you could connect to the SAE quick-disconnect O-Ring connector that comes with the Deltran chargers (see below) our Deltran is fused at a higher level (7.5 amps) than the 5 amps that may be ideal for your CPAP. Easier to just hook up two separate connectors to the battery so you can fuse appropriately.

We use a standard auto cigarette lighter 5 volt USB charger in our NOCO adapter socket. Since you are so close to battery capacity for your wife's CPAP usage over 5 nights you may not be able to support this with one battery unless you move to one with higher capacity (e.g. 55 amp hour @ 38 lbs. or buy a second battery as CapnLoki mentioned). Note that some camp sites may provide a charging station for batteries used for medical devices - if so you will be fine.

Charger:

Regarding the charger, the Deltran is a good model though with a 35 amp hour battery you can charge it at a faster rate. The 1.25 amp charger will take almost a day to fully recharge from an 80% discharge level. I've had good results with the Deltran 3 amp Battery Tender Plus charger at Costco that is only $39 and will charge more than twice as fast. If you are not a Costco member Deltran has a 5 amp version that will be within the specs of a 35 amp hour battery. Note that the Costco version comes with a fused SAE connector with O-rings that connect directly to the battery. The charger plugs directly into this. The charger you selected also includes one.

Costco Link: ttps://www.costco.com/Battery-Tender-Power-Plu ... 41973.html

Don't forget electrical tape to cover any bare terminals/connections inside the box for added safety. Feel free to reach out with additional questions. You may also need some nuts and bolts with locknut washers to connect your O-Ring connectors to the battery. Hope this helps.

Note that during the off-season you will need to charge the battery every three months and after 6 months of storage cycle it 20-30% and then recharge to avoid sulfation.

Thank you Lane for the reply. I do have a few questions, so please bear with me.

You were talking about needing to change out fuses on the quick disconnect. Can you explain that more? When its connected to the CPAP you use a 5A fuse but what do you use when its connected to charger? Or is that where you are talking about using a separate quick disconnect at 7.5A?

Is there a way to monitor my usage on the battery? There was a device mentioned by CapnLoki earlier in the thread but it looks to need to be spliced in. Is there any way to do it without splicing in?

I'm starting to consider a smaller secondary battery (18AH? 20AH?) to support maintaining of the speaker and cellphones for music.

Thanks again for the insight. Both you and have CapnLoki have been a big help and this is turning in to something that doesn't seem to be too difficult to pull off, just trying to figure out how to size it correctly.

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