Charging an AGM Battery in a Delica

Submitted: Saturday, Jul 02, 2011 at 20:21

ThreadID: 87335 Views:5726 Replies:3 FollowUps:19

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Battery Power

In this article we explain why you might need an additional power source independent of the starting battery installed into your vehicle and we look in detail at types of batteries,

Stan2.8D

Hello Everyone, first post and thanks to all for a great site; it has been very helpful but have got to the point where I need to ask a specific question so here goes.

Have just bought a 2.8 diesel Delica and am in the process of turning it into a camper van(ette).

I am trying to work out the best way to provide aux power and have been through most of the options, I think, and cant seem to come to much of a satisfactory conclusion.
I need to run a 55L upright Engel which draws I think 2.5 amps max and a CPAP machine at night (sleep apnea ventilator) say 6-7 hours, draws between 1-4 amps depending if I use the humidifier or not. Other vitals would be say 2 or 3 12v led lights (if they give out enough light, I dont know) and a small notebook/laptop.
A small tv would be nice but I can do without. I may possibly add a Webasto 2000 diesel heater which has a 12v fan I think. Thats about it.

Options:
Solar panel on the roof: glass panel blows off driving along or gets nicked, needs to be parked in the sun or set up on a stand, needs storage space when not in use, cant really be left unattended at a campsite etc, needs to be angled if on a roof and moved around etc etc etc.
Generator for daytime charging: need to carry unleaded as well as spare diesel. Unleaded not always available in out of the way places. Storage space for generator and fuel not really available. Diesel generators too big. Even quiet generators are not that quiet and any decent portable generator is a pricey item.

240v installation in a Delica seems like overkill and ties me to paying for a powered site again and again which will get v expensive quickly on a long trip and I am not a big fan of the goldfish bowl experience in powered site alley....... ooooh he's having macaroni cheese again tonight. that kind of thing.

I like to try and keep things simple if possible: fewer items and dual purpose whatever equipment I do carry.

So I have come down to trying to work out a set up where I could charge the deep cycle battery with the engine but I cant seem to find out for how long I would need to do this, how often and if the car can idle or needs to be driven and whether the existing 90amp alternator needs to be upgraded to the 120amp (I think this is possible) and the best size/make/type of battery to get. Dual use deep cycles might take a quicker charge?
As these batteries are apparently best used at a discharge of about 50% or less (but not too much less), I dont know what size would be best. Golf cart, fork lift, marine: I dont know which would be best and have seen them all suggested as best for this sort of use.

If anyone could help that would be great, many thanks
Stan

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Reply By: Bigfish - Saturday, Jul 02, 2011 at 21:02

Saturday, Jul 02, 2011 at 21:02

Mate, there are so many threads on this forum that if you take the time to research them you will find the answer to your problem AND pick up valuable info along the way.
cheers

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AnswerID: 459034

Follow Up By: Stan2.8D - Saturday, Jul 02, 2011 at 21:06

Saturday, Jul 02, 2011 at 21:06

Thanks but as I said I have already done what you suggested and only then posted my question when I couldnt find the answer(s).

FollowupID: 732587

Reply By: Battery Value Pty Ltd - Saturday, Jul 02, 2011 at 21:04

Saturday, Jul 02, 2011 at 21:04

Hi Stan,

your nightly load requirement may look similar to this: fridge 15Ah (10hrs), cpap 25Ah (7hrs), lights 5Ah (5hrs), lappy 10Ah (3hrs), TV 12Ah (3hrs), fan 3Ah (3hrs), all up 70Ah. Or about 90Ah per 24hr period.
Recommended battery: 2x95Ah AGM 'deep cycle', total 190Ah capacity, max charging rate 50A combined.
Wire size between batteries and alternator: 8B&S, fused 60A at both ends, either manual or automatic isolation switch.
You need to budget for a daily alternator run time of 1.5 to 2 hours.
Also, a small inexpensive voltmeter (or multimeter) to read the battery voltage.
Batteries should get topped up on a weekly basis using a three stage mains powered charger.
Alternatively, you can use a small 60W solar panel with a solar regulator.
The regulator should be able to push the battery voltage up to 14.4 to 14.7V, and after an hour or so sitting at this voltage it should switch back to float voltage of 13.6 to 13.8V. Or, just disconnect the panel at this point in time.
Estimated cost for batteries, voltmeter, manual isolation switch, fuses (2x30A blade in parallel), wire and solar panel+regulator: $650.00.

Any questions, just fire away.
cheers, Peter

AnswerID: 459035

Follow Up By: Stan2.8D - Saturday, Jul 02, 2011 at 21:16

Saturday, Jul 02, 2011 at 21:16

Many thanks Peter, that is very helpful.
1.5 to 2 hours driving when I'm stopped and camping is not really do-able unless perhaps I can get a decent charge whilst the engine is idling (probably not I suspect).
I could perhaps turn the fridge off at night providing it isnt 40 degrees which would save on charging time a bit.
Are there any batteries on the market which will do the job AND accept a fast charge from a short drive or an idling engine?
Would an increase in alternator size make much difference to charging time do you think?
I suspect that as am planning to travel in winter, solar isnt going to be reliable enough to be sure of enough charge, in which case I can see that I will have to get a generator.

FollowupID: 732588

Follow Up By: Battery Value Pty Ltd - Saturday, Jul 02, 2011 at 21:34

Saturday, Jul 02, 2011 at 21:34

Anytime Stan,

you'd have to at least fast idle so that the alternator puts out a decent current, and secondly for good cooling of the diodes inside.

Turning off the fridge overnight helps but it'll have to work harder the next morning to take up the slack, so in a 24hr period, the energy savings aren't that great.

50 to 60A charging rate is pretty much all you can expect from an average size alternator. If you upgrade to a 120A unit, the max charging current won't increase much unless you select thicker wire, but this will hurt the 2x95Ah flat plate AGM batteries in the medium term.
For this, you could select spiral wound AGM batteries, you'd need 3x50Ah (2 times more expensive than flat plate AGM deep cycle).
This combo would be good for around 100A max charging rate, but only on a cool day (alternator generates a lot of heat at 100A). It also needs to rev at a decent speed for this.
This reduces your daily run time to about 45~60 minutes, but at a cost.

Note that you don't have to use solar on a daily basis to bring your batteries to 100% state of charge. The alternator does this for your up to around 85% SOC, use solar once per week to top up, or whenever the sun shines.

cheers, Peter

FollowupID: 732591

Follow Up By: Stan2.8D - Saturday, Jul 02, 2011 at 22:03

Saturday, Jul 02, 2011 at 22:03

If I reduce the consumption to:
Cpap no humidifier: 7Ah
Fridge: 15Ah
Lights: 5Ah
Laptop:6Ah
Fan for heater: 5Ah
Total: 38Ah or c.55Ah per 24 hrs

This would require perhaps one battery of say 120Ah?

Realistically I will need to use campsites from time to time so fast revving isnt going to work there or it means driving for probably around 1 hour every day and presumably not sitting in traffic.

This leaves either solar or a generator for daily charging when not on the road.
Solar once a week would work in winter but not if its needed every day and would probably require more than a 60w panel I suspect.

I can see that there is no realistic alternative to a generator in this scenario unless perhaps I get a gas fridge instead, then the alternator charging might be viable.

Thanks

FollowupID: 732595

Follow Up By: Stan2.8D - Saturday, Jul 02, 2011 at 22:32

Saturday, Jul 02, 2011 at 22:32

Peter, for this reduced consumption (with electric fridge) could you let me know what size of battery I would need and what size
Generator
or
Solar Panel
for everyday charging instead of relying on the engine?
many thanks

FollowupID: 732598

Follow Up By: Battery Value Pty Ltd - Saturday, Jul 02, 2011 at 22:39

Saturday, Jul 02, 2011 at 22:39

Stan,

the 120Ah flat plate AGM deep cycle battery only has a max charge acceptance rate of 30A, so there's potential for exceeding this rate even with an average alternator.
Yes, for your 55Ah figure, your solar panel needs to be specced at least 200W, so this is an expensive/impractical option.
Solar is only advisable in your situation if in connection with a high current bulk charging source. This reduces the panel to a more manageable size.

Note with the generator, you need a 25/30/50A rated charger (for 95Ah, 125Ah, or 2x95Ah battery) for quickest recharging times.

With your daily load of 55Ah, you can expect one 95Ah battery to power everything for one day. E.g. if you want to be 4 days without alternator/solar/generator, you'd be looking at installing 4 of these. But after this you have to come up with 240Ah of charge somehow.

Yes, running the fridge on gas would reduce the Ah required by around 50% in your situation.

cheers, Peter

FollowupID: 732599

Follow Up By: Stan2.8D - Saturday, Jul 02, 2011 at 23:26

Saturday, Jul 02, 2011 at 23:26

hmm, methinks my idea of a one solution fits all isnt going to work in this case.
Possibly the answer may be to fit the travelling to fit the charging requirements, to have a reasonably bigger battery storage capacity which will last longer, to charge this daily with either solar or genny without having to worry too much on topping right up and then to do the big charge after a few days (or more) by changing location.
This would mean that daily charging wouldnt be for too long, driving charging wouldnt be for too long and there is the ability to stay in one place for a while. The odd night at a camp site probably wouldnt require any daily charging at all.
By eliminating the heater (save about $2000) that gets rid of another 5Ah: north in the winter south in the summer......it works for the birds.

FollowupID: 732602

Follow Up By: Stan2.8D - Saturday, Jul 02, 2011 at 23:35

Saturday, Jul 02, 2011 at 23:35

Peter, would 2X95Ah plate batteries be the max I could put in and does it matter if one or both of them are not in the engine bay next to the main battery?
thanks

FollowupID: 732603

Follow Up By: Battery Value Pty Ltd - Saturday, Jul 02, 2011 at 23:48

Saturday, Jul 02, 2011 at 23:48

Stan,
you can put in as many batteries as you like :)
But two 95Ah (combined 190Ah) is pretty much the minimum for your load requirement, and intended way of (alternator) charging.

But I don't recommend to install them under the bonnet because they're not designed for hot environments. Actually no battery is, because the charge acceptance decreases dramatically with temperature (note that starter batteries only need to deliver ~0.5Ah for cranking, and afterwards the alternator supplies the chuice for all loads).
The charging current close to the alternator is also higher (less wire resistance), so mounting them outside the motor compartment is the preferred way anyway.

cheers, Peter

FollowupID: 732605

Follow Up By: Stan2.8D - Sunday, Jul 03, 2011 at 00:11

Sunday, Jul 03, 2011 at 00:11

ok, many thanks. I think I know which way I am heading with this.
Have seen some folding panels with quite high capacity for reasonable prices on the bay and people on here who have bought similar seem quite happy with them, so I may do that.
If I get you right, I can have as many 95Ah batts as I like but each one shouldnt be more than 95Ah.
I was thinking 3X95Ah and 160w panel used daily, with a 24hr usage of 50Ah and a drive of at least 1 to 2 hours at least every 4 to 5 days or thereabouts, should just about do it hopefully.

FollowupID: 732606

Follow Up By: Battery Value Pty Ltd - Sunday, Jul 03, 2011 at 10:45

Sunday, Jul 03, 2011 at 10:45

Stan,
may I recommend to get 2x100W or 2x120W panels, for better portability and other advantages.
Ditch the solar regulator which comes with them, or negotiate a better deal for the panels less regulator.
Instead, get a 20% more efficient temperature compensated MPPT regulator which has been software modified, for concurrent fridge operation while charging the batteries. This ensures the batteries won't get over/undercharged and as a benefit, it squeezes out every single Watt from the panel during the ever changing operating conditions (battery terminal voltage, amount and type of light, cell temperature, angle of incidence etc).
The Ah rating of each individual battery isn't important, just the sum of them.
If your nightly/daily load pattern calls for about 250~300Ah of battery capacity, you can select any Ah combination to land you in this band. So 3x95Ah (a total of 285Ah) would fit the bill nicely, and three of these are a lot easier/cheaper to buy/courier/handle to your location than one big monster of a 250Ah battery.

And for those overcast days, plan your drive for early morning, so that the panels have time to harvest some solar energy in an attempt to get the batteries up to their daily absorption dose of 14.4V. If you'd drive in the evening, the little bit of solar during the day won't do much in terms of absorption voltage, and the alternator isn't capable of doing this either because it's limited to around 13.8~14V. The key for understanding this is that the battery voltage rises only reluctantly while the SOC is low, but begins to rise faster as the SOC increases. So once bulk charging (high current, alternator) has pushed up the SOC to around 80%, a lower current (but higher voltage) source like solar can be utilised to reach absorption voltage fairly easily.
So the order of charging is bulk, absorption, float.
For bulk the alternator is ideal, for absorption and float you want solar (with a good regulator).

cheers, Peter

FollowupID: 732625

Follow Up By: Stan2.8D - Sunday, Jul 03, 2011 at 13:59

Sunday, Jul 03, 2011 at 13:59

Peter, the largest capacity folding panels from a seller who seems to have forum member's recommendation only does a kit upt to 160w. The other seller(s) who claim higher wattage folders seem a bit suspect.
2X100 w panels not made up into a convenient folding kit with integral stand would be bulky and cumbersone to put up and take down quickly. A folding kit could be made by someone more electrically minded than me and I have seem a post where someone has done this but as it stands 160w folding from a reputable seller is the max I can find.

With 3X95's, a long daily solar charge, and a max 24 hr use of 55Ah, surely there would be enough topping up from 160w to last 4 or so days until the next big drive as the solar charge dosent need to totally replenish the previous 24 hr usage so long as the interval till the next long drive is no more than say 4 days?

FollowupID: 732636

Follow Up By: Battery Value Pty Ltd - Sunday, Jul 03, 2011 at 15:07

Sunday, Jul 03, 2011 at 15:07

Stan,

sorry I actually meant 2 kits, 100 or 120W each (so there are 4 panels in total which keeps the size down when packed away).
Each kit with its own regulator, and both kits sharing the same 3x95Ah battery.

cheers, Peter

FollowupID: 732640

Follow Up By: apwaddo - Sunday, Jul 03, 2011 at 20:53

Sunday, Jul 03, 2011 at 20:53

peter,
Can you tell me which of the recognised suppliers of genuinely rated solar panles supply 100 watt panels?

FollowupID: 732663

Follow Up By: Battery Value Pty Ltd - Sunday, Jul 03, 2011 at 21:08

Sunday, Jul 03, 2011 at 21:08

sorry apwaddo, haven't done any testing of solar panels in recent times, so can't make a recommendation.
But all gear we sell, is being thoroughly tested on an ongoing basis by us to ensure it meets the manufacturer's speccs.

cheers, Peter

FollowupID: 732666

Follow Up By: apwaddo - Sunday, Jul 03, 2011 at 21:23

Sunday, Jul 03, 2011 at 21:23

Sorry Peter - I need to clarify - you have never tested any 100 watt Soalr panels yet you are reccommending them, despite the fact that no reputable manufacturer makes them?

FollowupID: 732670

Follow Up By: Battery Value Pty Ltd - Sunday, Jul 03, 2011 at 21:35

Sunday, Jul 03, 2011 at 21:35

apwaddo,

they're being made don't worry about that.
If you can't find that particular wattage in your neck of the woods, just select the next size up or down.
cheers, Peter

FollowupID: 732671

Follow Up By: Stan2.8D - Sunday, Jul 03, 2011 at 22:23

Sunday, Jul 03, 2011 at 22:23

4X panels even folding is going to be a royal pain in the neck to store and put up/take down I reckon. Is that extra 40w so crucial and if so why?

FollowupID: 732679

Reply By: Stan2.8D - Sunday, Jul 03, 2011 at 18:55

Sunday, Jul 03, 2011 at 18:55

Peter, down to what % can you discharge your Perigon spiral battery and do you know when you will be getting in more stock? thanks

AnswerID: 459100

Follow Up By: Battery Value Pty Ltd - Sunday, Jul 03, 2011 at 21:17

Sunday, Jul 03, 2011 at 21:17

Stan,

100% depth of discharge is no problem for ANY 'deep cycle' rated battery.

Look at feedback no7 from top by bad_benny who's done just that to test the real capacity of our flat plate 'deep cycle' AGM.

Most likely in about 6 to 7 weeks time we'll have more spiral wound ones for you.

cheers, Peter

FollowupID: 732668