Three 30 amp batteries v one 90 amp <span class="highlight">battery</span>
Submitted: Monday, Jun 13, 2022 at 10:01
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Member - Outback Gazz
G'day All
A good friend of
mine recently purchased an old Hino bus that was professionally converted into a motorhome quite a few years ago. It has 4 large solar panels on the roof (watts unknown) and has three 30 amp AGM batteries wired in parallel. The three 30 amp batteries are standard full size not small ones.
Would anyone know why 3 x 30 amp hr batteries would have been used instead of say of 1 x 90 amp hr
battery and would there be any reason he couldn't just put in 1 x 120 amp hr
battery ?
Cheers
Gazz
Reply By: Allan B (Sunshine Coast) - Monday, Jun 13, 2022 at 10:28
Monday, Jun 13, 2022 at 10:28
.
Hi Gaz,
The only benefit of several small batteries instead of one larger one is that the smaller ones may be easier to lift into position. There is no electrical benefit. In fact there can be some electrical problems with paralled batteries.
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640852
Follow Up By: Member - Outback Gazz - Monday, Jun 13, 2022 at 10:46
Monday, Jun 13, 2022 at 10:46
Howdy Allan
When my mate asked me why someone would put three small batteries in I said that it may have been for ease of lifting as the chap he bought the bus from was rather elderly - but then my mate said the old fella purchased the bus as is and that's how it was set up.
I just thought I would ask the good folk on here as I told him just to put in a 120 amp hr
battery and didn't want anything to go wrong and cause a barny down the track.
I will pass on your advice.
Thanks
Gazz
Ps - how'z the Sprinter going ?
FollowupID:
919900
Follow Up By: Allan B (Sunshine Coast) - Monday, Jun 13, 2022 at 21:20
Monday, Jun 13, 2022 at 21:20
.
Sprinter's going great Gaz. Drives like a dream and the internal setup is as good as hoped.
Longest trip so far is Sunshine coast to
Bendigo but about to leave for central Qld where it may be a bit warmer. Have deferred the WA trip until about August.
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Follow Up By: Member - Outback Gazz - Monday, Jun 13, 2022 at 21:28
Monday, Jun 13, 2022 at 21:28
Enjoy and take care !
Cheers
Gazz
FollowupID:
919923
Follow Up By: qldcamper - Tuesday, Jun 14, 2022 at 07:42
Tuesday, Jun 14, 2022 at 07:42
What direction you headed Allen?
I need to go to BH via
Adelaide early next month and idealy would like to go via Innaminka and
Flinders ranges but not looking good water wise atm.
Next choice was to follow the Darling down but not sure how high that will be by then, so might be leaving the camper at
home this trip.
Appriciate any condition reports you can offer along your way.
FollowupID:
919927
Follow Up By: Member - McLaren3030 - Tuesday, Jun 14, 2022 at 08:11
Tuesday, Jun 14, 2022 at 08:11
Hi Allan,
Without wanting to hijack this thread, great to hear that “Project Sprinter” is finally complete and on the road. Happy touring.
Macca.
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Follow Up By: Allan B (Sunshine Coast) - Tuesday, Jun 14, 2022 at 09:22
Tuesday, Jun 14, 2022 at 09:22
Hi qldcamper,
Which direction? I presume you mean to WA.
Down the Newel Hwy to Narrandera then via
Mildura to
Adelaide to visit friends. Then up around Pt
Augusta to the Eyre Hwy across the Nullarbor. All bitumen so no point in road reports (I sincerely hope!)
But we are hijacking this thread!!
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Follow Up By: qldcamper - Tuesday, Jun 14, 2022 at 09:48
Tuesday, Jun 14, 2022 at 09:48
Appologies to the OP, but i meant up into QLD.
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Follow Up By: Allan B (Sunshine Coast) - Tuesday, Jun 14, 2022 at 12:07
Tuesday, Jun 14, 2022 at 12:07
I have no idea. Just head NW and wander along, gypsy style.
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Follow Up By: qldcamper - Tuesday, Jun 14, 2022 at 12:09
Tuesday, Jun 14, 2022 at 12:09
Half your luck.
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Follow Up By: Allan B (Sunshine Coast) - Tuesday, Jun 14, 2022 at 12:12
Tuesday, Jun 14, 2022 at 12:12
Yep. The other half will be that all the other retirees don't have the same idea!
FollowupID:
919942
Reply By: Peter_n_Margaret - Monday, Jun 13, 2022 at 11:05
Monday, Jun 13, 2022 at 11:05
There is another benefit if there is a premature failure of one of the small batteries in that it can be easily replaced.
All of the batteries being discussed are actually 6 x 2 volt batteries in series.
Traditional off
grid systems used large 2 volt wet cells in series to build (usually) a 48V system. This allowed the replacement of a single cell in the event of a failure.
Cheers,
Peter
OKA196 motorhome
AnswerID:
640854
Follow Up By: qldcamper - Monday, Jun 13, 2022 at 11:19
Monday, Jun 13, 2022 at 11:19
Or just easily taken out of circuit to allow continued operation until in a location all 3 can be replaced at a reasonable cost.
But as Alan says, could create more problems than it is worth.
Some simple tests will warn you when it is getting close to time to replace deep cycle batteries.
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Follow Up By: Allan B (Sunshine Coast) - Monday, Jun 13, 2022 at 21:56
Monday, Jun 13, 2022 at 21:56
'
Peter,
I have worked with large "traditional" systems employing discrete 2 volt cells connected in series to produce 200 volts but such arrangements bear no comparison with 3x12v batteries in parallel which is the topic of this thread.
I did employ two 12v 100Ah batteries in parallel in my Troopy as it would be impossible to lift a 200Ah
battery into position even if such could be purchased. However I took the precaution of charging them independently with separate dc-dc chargers. This worked
well but it is still not good practice to run batteries in direct parallel charging for extended periods. You may get away with it but only with the "Luck of the Irish".
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Follow Up By: Member - lyndon NT - Saturday, Jun 25, 2022 at 06:49
Saturday, Jun 25, 2022 at 06:49
Hi Allan
" This worked
well but it is still not good practice to run batteries in direct parallel charging for extended periods. "
What if each of the batteries negative was
well bonded to the chassis? Is this the difference you are referring to when you say "direct parallel!?
Cheers
Lyndon
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920059
Follow Up By: qldcamper - Saturday, Jun 25, 2022 at 07:25
Saturday, Jun 25, 2022 at 07:25
European trucks and even Toyota land cruisers have been using series parallel
battery systems for many years charging in parallel quite successfully.
Dont understand the advantage of this in heavy vehicles over a straight 24 volt system but in the land cruisers it made sence.
Caterpillar use parallel configurations in many machines where space makes four smaller batteries a better option.
Most Cat machines that have 2 starter motors have 2 pairs of batteries connected in perminant parrallel.
Starting batteries do have a slightly different chemical and mechanical properties to deep cycle but the economics of worrying about it is not worth while.
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Reply By: Member - Bigfish - Monday, Jun 13, 2022 at 15:58
Monday, Jun 13, 2022 at 15:58
Maybe the original owner got the small batteries cheap. In any case I,d throw them all away and buy one x 120 a/h lithium. At around 10-12 kg the old bloke will have no trouble lifting. Will be far better than the set up now.
AnswerID:
640858
Follow Up By: Nomadic Navara - Tuesday, Jun 14, 2022 at 07:58
Tuesday, Jun 14, 2022 at 07:58
There are a lot of UPS (uninterruptible power supply) systems around designed for single computers. Their batteries are often replaced after a couple of years and are still in good condition. These are offered to tinkerers and others, possibly your old mate may have latched on these at a good price.
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Reply By: Member - McLaren3030 - Tuesday, Jun 14, 2022 at 08:17
Tuesday, Jun 14, 2022 at 08:17
Hi Gazz,
Personally, when these batteries have reached their “use by date”, I would be replacing them with a single 100 or 120 amp LiFePo4
battery and a DC/DC charger with an appropriate LiFePo4 profile. Would be more than half the weight of the three 30 amp Lead Acid batteries, and last far longer if properly looked after.
Macca.
AnswerID:
640865
Follow Up By: Member - lyndon NT - Saturday, Jun 25, 2022 at 06:54
Saturday, Jun 25, 2022 at 06:54
Hi Macca
Unless they are part of the large recall underway......., failed BMS, venting gases. Not nice, especially if you sleep inside the said vehicle.
I have been looking into this lately and have decided that I might hold off the change over.
I'd really want to be going with a name brand like Victron with separate BMS.
Cheers
Lyndon
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Follow Up By: Member - McLaren3030 - Saturday, Jun 25, 2022 at 08:36
Saturday, Jun 25, 2022 at 08:36
Hi Lyndon,
I am not sure I know what recall you are talking about. I haven’t heard about any recall. Can you please elaborate?
Macca.
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Reply By: Member - Cuppa - Tuesday, Jun 14, 2022 at 14:49
Tuesday, Jun 14, 2022 at 14:49
90 Ah or even 120Ah isn't much for a bus. Of course it depends on what is being powered from them, but most buses would have more than a single 120Ah
battery would manage.
AnswerID:
640869
Reply By: Dean K3 - Friday, Jun 17, 2022 at 18:08
Friday, Jun 17, 2022 at 18:08
Gazz,
working on basis of parallel wiring I'm presuming its a 12 volt system which is kind of odd for a old style vehicle unless its a 24/12 volt system ie 24 v start 12 v operate.
weight is one thought but space is also a option but with no picture3s to tell the story gets bit hard to give a semi techncial thought.
I would however investigate the solar panel voltages and watts hopefully a sticker still attached or readable on underneath of the panel.
id go with others suggestions of LIfepo4 as replacements but have a suitable BCDC charger fitted ideally batteries with intern BMS fitted
I do recall the days at motorola when techs had to lift manully a number of 200ah batteries into the comms room top of the QV1 building in
Perth for WA
police upgrade 200ah are PITA to move ! also to transport one very heavily (suspect overloadfd) Falcon ute to move them
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